A loss in pressure over time aids in finding pneumatic leaks. The system is pressurised and the drop in pressure is measured. There is always an allowance and the same with hydraulic systems. Leakage can be ignored if the drip from the source takes a measured time period to develop, otherwise, the component needs changing or the 'o' ring, which in most hydraulic or otherwise leaks it normally is. All this stuff is stipulated in the appropriate maintenance manual. This stuff is engineering 101, the very basics, but such things are usually checked during line maintenance operations.
Least resource intensive/easy to maintain aircraft of WW2?
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A loss in pressure over time aids in finding pneumatic leaks. The system is pressurised and the drop in pressure is measured. There is always an allowance and the same with hydraulic systems. Leakage can be ignored if the drip from the source takes a measured time period to develop, otherwise, the component needs changing or the 'o' ring, which in most hydraulic or otherwise leaks it normally is. All this stuff is stipulated in the appropriate maintenance manual. This stuff is engineering 101, the very basics, but such things are usually checked during line maintenance operations.
ThomasP
Senior Master Sergeant
Just some thoughts.
Is it possible, under WWII wartime conditions, to evaluate the question that is the OP?
The reason I pose this question is due to the various areas/aspects that contribute to what we call maintainability, along with how often the matter came into play during the war.
I have read many anecdotal accounts of unusual reliability/unreliability of engines for example. I have read of only a few 'proven' accounts of unusually good reliability of systems. Many times a system is referred as 'acceptable' or 'reliable' or various perjoratives, but no measured values are provided.
Also, how do we think the matters of availability or durability should be taken into account. And for authoritative accounts of reliability/availability/maintainability we would need the maintenance and service records for the various aircraft, or at least an official after-acton analysis of the problem.
Using the late Hurricane Mk I and late Spitfire Mk I as examples. Both used the Merlin III engine, either the DH or Rotol constant speed propeller, and the same armament of 8x .303 cal Brownings. The late Hurricane Mk I used tube-frame construction with wood and fabric covering for the fuselage and tail, and Warren truss/semi-monocoque construction for the (metal) wings. The late Spitfire Mk I use monocoque construction throughout. Both were fitted with split flaps and Frise ailerons, with all(?) control surfaces being fabric covered. Both had hydraulic powered main undercarriage and fixed tail wheel.
Anecdotal accounts say that the Hurricane was more rugged than the Spitfire. In theory this should mean that it was also more maintainable, as it implies that the airframe (fuselage/wings/tail/landing gear) as a whole needed less maintenance.
From what I have read (both official and anecdotal) it was easier on average to repair damage on the Hurricane, and more of the damaged Hurricane airframes were repairable at the squadron level.
Relative to the Merlin engine installations, I have not read of any significant differences.
Relative to the propellers I have not read of any significant difference.
For the 8x .303 cal armament the only difference I have read of is in the time of turn-around - in this case the Spitfire either required more time or more manpower to accomplish.
The undercarriage of the Spitfire seems to have been significantly more prone to damage - at least on the Seafire variants when operating from CVs - than the Hurricane's undercarriage.
The wood and fabric covering on the Hurricane fuselage would (it seems to me) require more routine maintenance than the metal skinning on the Spitfire.
Which of the above aspects should we use to answer the OP?
If we had radial air-cooled engined variants of the Hurricane and Spitfire to compare to the Merlin powered reality, we could maybe get some examples of the differences in maintenance man-hour required. Maybe the P-36 Hawk would work for comparison(?) - but I have not run across any reports that include information that can be used to do so.
As has been pointed out up-thread, smaller & simpler airframes would have required relatively low maintenance times. But we are talking about engines that have an output of .3-.4 hp/in3 as opposed to .6-.7 hp/in3 of the Merlin or R-1820 engines, and airframes that have wingloadings of 10-15 lbs/ft2 and not fast enough to even pull more than 3g instantaneous.
Is it possible, under WWII wartime conditions, to evaluate the question that is the OP?
The reason I pose this question is due to the various areas/aspects that contribute to what we call maintainability, along with how often the matter came into play during the war.
I have read many anecdotal accounts of unusual reliability/unreliability of engines for example. I have read of only a few 'proven' accounts of unusually good reliability of systems. Many times a system is referred as 'acceptable' or 'reliable' or various perjoratives, but no measured values are provided.
Also, how do we think the matters of availability or durability should be taken into account. And for authoritative accounts of reliability/availability/maintainability we would need the maintenance and service records for the various aircraft, or at least an official after-acton analysis of the problem.
Using the late Hurricane Mk I and late Spitfire Mk I as examples. Both used the Merlin III engine, either the DH or Rotol constant speed propeller, and the same armament of 8x .303 cal Brownings. The late Hurricane Mk I used tube-frame construction with wood and fabric covering for the fuselage and tail, and Warren truss/semi-monocoque construction for the (metal) wings. The late Spitfire Mk I use monocoque construction throughout. Both were fitted with split flaps and Frise ailerons, with all(?) control surfaces being fabric covered. Both had hydraulic powered main undercarriage and fixed tail wheel.
Anecdotal accounts say that the Hurricane was more rugged than the Spitfire. In theory this should mean that it was also more maintainable, as it implies that the airframe (fuselage/wings/tail/landing gear) as a whole needed less maintenance.
From what I have read (both official and anecdotal) it was easier on average to repair damage on the Hurricane, and more of the damaged Hurricane airframes were repairable at the squadron level.
Relative to the Merlin engine installations, I have not read of any significant differences.
Relative to the propellers I have not read of any significant difference.
For the 8x .303 cal armament the only difference I have read of is in the time of turn-around - in this case the Spitfire either required more time or more manpower to accomplish.
The undercarriage of the Spitfire seems to have been significantly more prone to damage - at least on the Seafire variants when operating from CVs - than the Hurricane's undercarriage.
The wood and fabric covering on the Hurricane fuselage would (it seems to me) require more routine maintenance than the metal skinning on the Spitfire.
Which of the above aspects should we use to answer the OP?
If we had radial air-cooled engined variants of the Hurricane and Spitfire to compare to the Merlin powered reality, we could maybe get some examples of the differences in maintenance man-hour required. Maybe the P-36 Hawk would work for comparison(?) - but I have not run across any reports that include information that can be used to do so.
As has been pointed out up-thread, smaller & simpler airframes would have required relatively low maintenance times. But we are talking about engines that have an output of .3-.4 hp/in3 as opposed to .6-.7 hp/in3 of the Merlin or R-1820 engines, and airframes that have wingloadings of 10-15 lbs/ft2 and not fast enough to even pull more than 3g instantaneous.
Some good questions, Tom, as expected from a thoughtful individual such as yourself. I certainly won't state that I'll be able to provide definitive answers to your statements, but hopefully I can at least add to them.
Anecdotally, yes, but the nature of the Hurricane's construction meant that the rigors of service life affected it differently, but only those different areas as both types shared structural commonality. I have not seen any real evidence that the Hurricane did not suffer as much as the Spitfire, but light repair to its fabric rear fuselage was easier to do at squadron level. The Hurricane's fuselage was, as you mentioned, steel tube covered in fabric, but the wing centre-section, to which the engine was mounted was a strong unit made of metal. Its outer wings were originally fabric covered but were a metal endo-skeleton, like its control surfaces. The Spitfire's fuselage employed what we would today describe as conventional construction, its semi monocoque stressed skin being more akin to modern aircraft. The Hurricane's fabric covering was easier to repair damage to, but its fin, hori stab and wings on all marks from mid 1939 onwards were light gauge aluminium, like the Spitfire, so no difference in repair techniques.
It depends on the type of damage and the RAF categorised damage accordingly depending on its severity as to whether it could be repaired at squadron level or required more intensive repair at a repair depot. This applied to all types, not just Spits and Hurris. A simple fabric patch on a control surface was easy to repair, which applied to both types, but access to the rear fuselage structure was easier on a Hurricane because it was fabric covered. Patching a stressed skin is certainly more time-consuming owing to the nature of stressed skin construction, not to mention access to the damaged section to rivet the patch; the dolly holder needs access to the inside to form the rivet tails, for example.
Hurricanes could be and were overhauled at maintenance units more quickly and more extensively than Spitfires; in fact, Hurricane maintenance and repair figures are blurred because of the extent to which aircraft were modified and re-rolled out after repair. Mk.Is often ended up as Mk.IIs after a repair/rebuild at an MU and parts of one airframe were fitted to another, so even tracking serial numbers takes quite a bit of detective work in the archives when it comes to researching repaired Hurricanes.
The Seafire's undercarriage was not specifically prone to damage, but its narrow track caused issues compared to the Hurricane's. The problem with the Seafire's and Sea Hurricanes' undercarriages was two-fold; they were not designed for the forces that are encountered in carrier landings, all that energy from an approach speed of 70 kts being absorbed and transferred in a matter of a few metres rather than a few hundred metres took its toll, and the oleos were not designed to absorb that massive impact, not having much travel, which caused issues with both types. Both tended to bounce on landing because the oleos were not pressurised to accept the forces imposed on them. The Seafire's undercarriage was modified in later variants to take the punishment, but the Sea Hurricane's undercarriage never was as it was only intended as an expedient, so it never received the same extent of modification that the Seafire did.
It's worth noting that someone here on this forum produced figures that showed that Seafires did not suffer an appreciably higher rate of accidents compared to other contemporary carrier-based fighters, but myths have a tendency to grow from presumptions, not only that, but there are people who regularly come on here to bag the poor carrier based Spitty out for sport!
I've not seen any evidence of this, it is worth pointing out that the Hurricane was an all-metal aircraft with a fabric rear covering, the only wooden bits were stringers for shaping the rear fuselage and a section aft of the cockpit called the Dog Box. None of its structural load bearing members were wood. In the earliest Mk.Is the outer wing panels were fabric covered but their internal structure was all-metal. This was changed to metal skinning in 1939 on the production lines. The wooden stringers were not particularly difficult to repair, nor was the fabric covering. It's worth noting that the Hurricane shared structural elements with its Hawker designed predecessors in the Hart/Hind and Fury family of biplanes, their construction methods were the same, so the Hurricane was closer to what was already known and practised within the RAF when it entered service. This meant that engineers who received the Hurricanes in service first would not have required as much training as engineers working on Spitfires. Sheet metal work is a different kettle of fish to fabric covered tubular structures and that would have meant engineers would have required extra training if they had not learned sheet metal work at the time they were in basic training.
It all adds to the narrative but as I've mentioned it does depend on numerous factors as to what could be considered more maintenance friendly and, more significantly, by whom. As I mentioned in another thread, an engineer working on the frontline at an 11 Group airfield on Spitfires getting airborne as often as three times a day is going to get pretty nifty at ramp servicing (servicing the aircraft in-between flights), as opposed to engineers at an airfield in 13 Group, where the action in the summer of 1940 was not as hot. Availability of parts was also an issue, engineers at dispersed airfields would find that part supply relied on bits being driven to their dispersed airfield rather than through the usual channels to regular bases, for example, which would have hindered the pace of maintenance. Regarding loading ammunition to the aircraft's guns, Hurricanes had their guns located under one door, closely grouped together, with their ammo tracks being placed either side of the guns, whereas the Spitfires had their guns spaced across the wingspan, so separate doors and access, which was definitely more time consuming to load, but again, there are different factors to consider. If the ramp team is numerous, then the Spitfire's widely spaced gun bays can be accessed by a larger number of people, one per gun, whereas the Hurricane's ammo bays are closer together meaning one person has to access the ammo chutes of two guns, otherwise you'll have guys getting in each other's way.
On the face of it, the Hurricane certainly appears to be more maintenance friendly, but it's not a big difference and skill and experience of the maintenance team and location all plays a part in determining which one was more efficiently maintained. Overall, the Spitfire was universally loved, whereas the Hurricane was respected and admired. There's a difference. It's subtle, though.
Anecdotally, yes, but the nature of the Hurricane's construction meant that the rigors of service life affected it differently, but only those different areas as both types shared structural commonality. I have not seen any real evidence that the Hurricane did not suffer as much as the Spitfire, but light repair to its fabric rear fuselage was easier to do at squadron level. The Hurricane's fuselage was, as you mentioned, steel tube covered in fabric, but the wing centre-section, to which the engine was mounted was a strong unit made of metal. Its outer wings were originally fabric covered but were a metal endo-skeleton, like its control surfaces. The Spitfire's fuselage employed what we would today describe as conventional construction, its semi monocoque stressed skin being more akin to modern aircraft. The Hurricane's fabric covering was easier to repair damage to, but its fin, hori stab and wings on all marks from mid 1939 onwards were light gauge aluminium, like the Spitfire, so no difference in repair techniques.
It depends on the type of damage and the RAF categorised damage accordingly depending on its severity as to whether it could be repaired at squadron level or required more intensive repair at a repair depot. This applied to all types, not just Spits and Hurris. A simple fabric patch on a control surface was easy to repair, which applied to both types, but access to the rear fuselage structure was easier on a Hurricane because it was fabric covered. Patching a stressed skin is certainly more time-consuming owing to the nature of stressed skin construction, not to mention access to the damaged section to rivet the patch; the dolly holder needs access to the inside to form the rivet tails, for example.
Hurricanes could be and were overhauled at maintenance units more quickly and more extensively than Spitfires; in fact, Hurricane maintenance and repair figures are blurred because of the extent to which aircraft were modified and re-rolled out after repair. Mk.Is often ended up as Mk.IIs after a repair/rebuild at an MU and parts of one airframe were fitted to another, so even tracking serial numbers takes quite a bit of detective work in the archives when it comes to researching repaired Hurricanes.
The Seafire's undercarriage was not specifically prone to damage, but its narrow track caused issues compared to the Hurricane's. The problem with the Seafire's and Sea Hurricanes' undercarriages was two-fold; they were not designed for the forces that are encountered in carrier landings, all that energy from an approach speed of 70 kts being absorbed and transferred in a matter of a few metres rather than a few hundred metres took its toll, and the oleos were not designed to absorb that massive impact, not having much travel, which caused issues with both types. Both tended to bounce on landing because the oleos were not pressurised to accept the forces imposed on them. The Seafire's undercarriage was modified in later variants to take the punishment, but the Sea Hurricane's undercarriage never was as it was only intended as an expedient, so it never received the same extent of modification that the Seafire did.
It's worth noting that someone here on this forum produced figures that showed that Seafires did not suffer an appreciably higher rate of accidents compared to other contemporary carrier-based fighters, but myths have a tendency to grow from presumptions, not only that, but there are people who regularly come on here to bag the poor carrier based Spitty out for sport!
I've not seen any evidence of this, it is worth pointing out that the Hurricane was an all-metal aircraft with a fabric rear covering, the only wooden bits were stringers for shaping the rear fuselage and a section aft of the cockpit called the Dog Box. None of its structural load bearing members were wood. In the earliest Mk.Is the outer wing panels were fabric covered but their internal structure was all-metal. This was changed to metal skinning in 1939 on the production lines. The wooden stringers were not particularly difficult to repair, nor was the fabric covering. It's worth noting that the Hurricane shared structural elements with its Hawker designed predecessors in the Hart/Hind and Fury family of biplanes, their construction methods were the same, so the Hurricane was closer to what was already known and practised within the RAF when it entered service. This meant that engineers who received the Hurricanes in service first would not have required as much training as engineers working on Spitfires. Sheet metal work is a different kettle of fish to fabric covered tubular structures and that would have meant engineers would have required extra training if they had not learned sheet metal work at the time they were in basic training.
It all adds to the narrative but as I've mentioned it does depend on numerous factors as to what could be considered more maintenance friendly and, more significantly, by whom. As I mentioned in another thread, an engineer working on the frontline at an 11 Group airfield on Spitfires getting airborne as often as three times a day is going to get pretty nifty at ramp servicing (servicing the aircraft in-between flights), as opposed to engineers at an airfield in 13 Group, where the action in the summer of 1940 was not as hot. Availability of parts was also an issue, engineers at dispersed airfields would find that part supply relied on bits being driven to their dispersed airfield rather than through the usual channels to regular bases, for example, which would have hindered the pace of maintenance. Regarding loading ammunition to the aircraft's guns, Hurricanes had their guns located under one door, closely grouped together, with their ammo tracks being placed either side of the guns, whereas the Spitfires had their guns spaced across the wingspan, so separate doors and access, which was definitely more time consuming to load, but again, there are different factors to consider. If the ramp team is numerous, then the Spitfire's widely spaced gun bays can be accessed by a larger number of people, one per gun, whereas the Hurricane's ammo bays are closer together meaning one person has to access the ammo chutes of two guns, otherwise you'll have guys getting in each other's way.
On the face of it, the Hurricane certainly appears to be more maintenance friendly, but it's not a big difference and skill and experience of the maintenance team and location all plays a part in determining which one was more efficiently maintained. Overall, the Spitfire was universally loved, whereas the Hurricane was respected and admired. There's a difference. It's subtle, though.
HiWell, they had rigged up and tested the Tiger Moth with a pair of racks each holding four 20lb bombs. Which was twice the load that most WW British fighters could carry.
tests were done with the racks under the rear cockpit and with the bombs under the lower wing.
The big problem is the lack of training. No practice bombs available and apparently the idea of using bricks didn't work. (Moth could out dive a tumbling brick ?)
While experienced pilots might have gotten away with it asking student pilots to spot targets on the ground, perform the desired attack profile ( climb to 800ft and then dive to 500ft while maintaining sight line to target and do this while trying to avoid ground fire AND keep an eye out (and they were flown as single seaters) for hostile fighters seems to asking a bit much.
With that said, the Gladiator
View attachment 690874
Isn't quite as simple as it appears.
The rigging/flying wires need attention.
It does have flaps on the both wings (manual?)
You have ailerons on both wings.
I believe it has wheel brakes.
There is a spring suspension in the wheel hubs.
The prop is fixed pitch so that is good. And the Metal one you could fix with a hammer
Not sure sure changing the plugs on the radial 9 is easier than the V-12 or not.
The V-12 doesn't use grease fittings on the valve gear.
It carries the same radios as an early Hurricane/Spit.
only 4 guns but two need synchronizers.
The Dowty oleo-pneumatic wheel of the Gladiator:
The first image from 'Metal Aircraft Construction' by Langley, the second two from 'Aeronautical Engineering' Edited by R A Beaumont. The Gloster Gladiator used Hawker construction techniques, so moving to Hurricane production was not too difficult. The Hawker techniques were progressively introduced on the Gauntlet Mk. II, the final production batch using it throughout.
Mike
Hi
RAF Servicing from 'my day' as per my training notes:
I worked on BASE 3 Servicing on VC10s at Brize Norton (as well as Bay work on components of VC10, Britannia and Belfast aircraft), on Wessex helicopters on 72 Sqn. we did 25, 75 and 150 hour servicings.
Mike
That's great info but looks rather convoluted. Surely it could have been simplified. The term "Base" servicing is still in use today, Base Maintenance is used to describe heavy maintenance by some operators. What aircraft are we talking about in "your day", Mike? I worked on C-130s, P-3s and UH-1s, aside from various airlinery types.
ThomasP
Senior Master Sergeant
Hey nuuumannn,
Thanks for the info.
re the "least-resource-intensive" part of the OP.
How do we measure this for this thread? We can use maintenance man hours to get something of an idea, particularly for the airframe types that were detail maintained. But does this apply to the armed forces and/or airframe types that used a fair amount of what were effectively LRUs? Also what types/levels of maintenance and repair do we use.
Some examples are:
The Darne 7.7mm MG. Although we do not have much on the long-term maintainability of the French aircraft (due to the short duration of their air activities) the idea behind the Darne was close to the one-use concept, ie the weapon was designed to be used for a given number of rounds and then effectively thrown away. There was I believe a plan to return the guns to a factory type repair center where some of the parts were to be rescued for reuse, but no repair was to be done in the field under normal circumstances.The Darne was produced to a standard that met the reliability and durability requirement for the total number of rounds it was required to fire. Do we count the man hours required to manufacture the Darne vs the man hours required to detail maintain a 7.7mm Browning?
The same goes for propellers to a certain degree (I think). I do not know much about the maintenance/repair of the cans/hubs, but I am under the impression that all types of blades could be repaired if the damage was not too serious - the limits depending on the type of blade and extent of damage. Aluminum and steel blades were often(?) straightened and had minor nicks and such repaired and/or tips reduced. Wood blades tendered to suffer more permanent damage due to breakage, but I have read that due to the wood blades breaking the hubs and/or reduction gear boxes were less likely to suffer damage. If the air force had replacement blades galore, and they simply replaced the blades or hubs rather than repair them, do we count the man hours needed to manufacture the blades and hubs - or just the time to replace the blades?
The A6M Zero. The overall maintenance record of the Zero shows that it was relatively reliable and easy to maintain. But, as has been brought up in other threads, the center fuselage section and wing were built as a unit - so any major damage to either required the replacement of both, with the center section being sent back to the factory if salvageable. I assume that the initial purchase orders/costs included some spares for rebuilding an airframe, but out on the islands they would have quickly become unavailable due to logistics issues. How does cannibalization count toward reliability and maintainability? How often did the center section need to be replaced? Did the concept payoff due to operational considerations?
By the end of the war, to a certain extant the USN was treating entire airframes operated off of CVs as one-use articles. If an airframe would require more than a certain number of man-hours to repair the aircraft would be set aside or tossed over the side. This last example may not apply to the OP, as it is replacing an airframe as opposed to maintaining it, but the range of the concept goes from the Darne to what % of the airframe?
Just some more thoughts & questions.
Thanks for the info.
re the "least-resource-intensive" part of the OP.
How do we measure this for this thread? We can use maintenance man hours to get something of an idea, particularly for the airframe types that were detail maintained. But does this apply to the armed forces and/or airframe types that used a fair amount of what were effectively LRUs? Also what types/levels of maintenance and repair do we use.
Some examples are:
The Darne 7.7mm MG. Although we do not have much on the long-term maintainability of the French aircraft (due to the short duration of their air activities) the idea behind the Darne was close to the one-use concept, ie the weapon was designed to be used for a given number of rounds and then effectively thrown away. There was I believe a plan to return the guns to a factory type repair center where some of the parts were to be rescued for reuse, but no repair was to be done in the field under normal circumstances.The Darne was produced to a standard that met the reliability and durability requirement for the total number of rounds it was required to fire. Do we count the man hours required to manufacture the Darne vs the man hours required to detail maintain a 7.7mm Browning?
The same goes for propellers to a certain degree (I think). I do not know much about the maintenance/repair of the cans/hubs, but I am under the impression that all types of blades could be repaired if the damage was not too serious - the limits depending on the type of blade and extent of damage. Aluminum and steel blades were often(?) straightened and had minor nicks and such repaired and/or tips reduced. Wood blades tendered to suffer more permanent damage due to breakage, but I have read that due to the wood blades breaking the hubs and/or reduction gear boxes were less likely to suffer damage. If the air force had replacement blades galore, and they simply replaced the blades or hubs rather than repair them, do we count the man hours needed to manufacture the blades and hubs - or just the time to replace the blades?
The A6M Zero. The overall maintenance record of the Zero shows that it was relatively reliable and easy to maintain. But, as has been brought up in other threads, the center fuselage section and wing were built as a unit - so any major damage to either required the replacement of both, with the center section being sent back to the factory if salvageable. I assume that the initial purchase orders/costs included some spares for rebuilding an airframe, but out on the islands they would have quickly become unavailable due to logistics issues. How does cannibalization count toward reliability and maintainability? How often did the center section need to be replaced? Did the concept payoff due to operational considerations?
By the end of the war, to a certain extant the USN was treating entire airframes operated off of CVs as one-use articles. If an airframe would require more than a certain number of man-hours to repair the aircraft would be set aside or tossed over the side. This last example may not apply to the OP, as it is replacing an airframe as opposed to maintaining it, but the range of the concept goes from the Darne to what % of the airframe?
Just some more thoughts & questions.
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FLYBOYJ
"THE GREAT GAZOO"
There are limits on propellers for blade erosion and dings. You are right about the wood blades but over the years it's been a practice to tear down any engine or gearbox that has had a "sudden stoppage" because of a prop strike, no matter how minor. Usually when a prop goes out of limits in the field, it's a matter of R&R and the prop is sent to a backshop for repair/ overhaul
The Zero was said to be easy to maintain but interchangeability was poor and the Japanese did not have good logistics support in the SWP. I would stick my neck out to say that just as many Zeros were lost due to lack of parts as in combat! I don't think much thought was put into logistic support as many didn't think the war would last as long as it did.
That decision would be left to the onsite maintenance chief/ maintenance officer and the resources they had available to repair damaged aircraft (to include manpower)
Geoffrey Sinclair
Staff Sergeant
- 777
- Sep 30, 2021
Where does the quicker overhaul figure come from? There were 100 Hurricane I converted to IIA and given new serials between BV155 and 174, DG612 and 651, DR339 and 374, DR391 and 394. All the other conversions retained their serial numbers. The Hurricane serial number list is as solid as the Spitfire one.
In Canada 30 CCF built RAF order Hurricane I received RCAF serials when taken into service with the RCAF, while already having RAF serials. 150 CCF Hurricane XII built RCAF order received RAF serials when taken into service with the RAF, while already having RCAF serials.
Stephen Bungay in his book The Most Dangerous Enemy has a break down of RAF losses 10 July to 11 August 1940, of the 115 combat losses 87 were to Bf109, 6 to Bf110, 13 to Luftwaffe bombers, 4 to collision, 1 to flak, 1 to friendly fire and 3 to unknown causes. Of the 106 damaged RAF fighters 52 were due to Bf109s, 38 by bomber gunners. In effect 13% of the fighters hit by bomber gunners were shot down, compared with 62% of the fighters hit by BF109s. In pilot casualties, half the pilots in the fighters hit by Bf109s were killed, compared with 10% of the fighters hit by bomber gunners.
The BF109s hit 63 Hurricanes, 63 Spitfires, 6 Defiants and 7 Blenheims, shooting down 45 of the Hurricanes, 31 of the Spitfires and 11 of the Defiants and Blenheims. The bomber gunners hit 25 Hurricanes and 25 Spitfires, shooting down 11 Hurricanes and 2 Spitfires. In all 51 Hurricane and 25 Spitfire pilots were killed. A number thanks to inadequate air sea rescue.
The book attributes the difference in survival rate to the Hurricane fuselage fuel tank initially not being self sealing, the vulnerability of the Hurricane wing fuel tanks and the Bf109 cannon shells. Apparently the shells tended to explode on contact with the Spitfire stressed skin but would penetrate the fabric covered Hurricane fuselage before exploding.
My count of The Battle of Britain Then and Now losses has 401 Spitfires as damaged, 364 destroyed, versus 490 Hurricanes damaged and 586 destroyed and undoubtedly there were other lightly damaged aircraft repaired at unit level without any record being made.
Air 20/2037 has figures for strength serviceability for Hurricanes and Spitfires every 7 days, 7 July to 3 November 1940, on average over the 18 weeks worth of reports 90.16% of Hurricanes on strength were serviceable, versus 88.24% of Spitfires. The Hurricane figure varied from 86.73 to 92.67%, the Spitfire 81.91 to 91.19%. The serviceable figures look high but should be consistent for both types. July to October 1940 the repair system output was 439 Hurricanes and 249 Spitfires.
No information on ease of maintenance which would include ease of access, things like the size, shape and location of inspection panels.
Hi
Vickers (BAC) VC10 (10 Sqn) major servicing, Bristol Britannia (99 and 511 Sqns) and Short Belfast (53 Sqn) components during bay servicing at Brize Norton plus Westland Wessex HC.2 on 72 Sqn. at Odiham.
Mike
So, more Hurricanes than Spitfires, what does that tell you?
I didn't provide figures, sooo...? At least that was my understanding based on the fact that a greater number of Hurricanes were overhauled within a given time period. I have not read exact figures, but had seen it written before, and you have kindly provided that information.
The added info from Bungay and After the Battle that you supplied doesn't really add anything to a discussion on maintenance, which has little to do with loss figures to enemy aircraft. The serviceability percentages is very useful as it does directly pertain to serviceability through maintenance, so thanks for that.
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If you look at the stats from the BoB the Spit was harder to hit than the Hurricane and because of it's higher performance could engage where the Hurri couldn't, also the Hurri was in service earlier so was a known aircraft, all this stuff adds up, the Hurri was easier to repair but needed to be repaired more often while most likely engaging in less combat, same could be said for the P47, the P47 is regarded as being a tough plane but ground attack sorties would have sent it's maintenance costs through the roof.
They were easier to hit so more needed repairing, there was more of them, being in service longer they were known by the maintenance guys, all the above?.
Thanks again, Tom, once gain I can't say I'll be able to fully answer your queries and Joe stepping in helps...
Regarding maintenance hours, yes, that's a good measure of reliability, or more relatably time spent on the ground. Using my own experience, which doesn't equate to the same as WW2 aircraft maintenance, but might help contextually, airlines make money when their aircraft are in the air, so having them on the ground undergoing maintenance is anathema to their very existence, hence why line maintenance is done at night between day operations. Heavy maintenance is a fact of life and affects aircraft availability, the schedules that Mike Meech provided give us a good clue as to aircraft servicing times for the RAF, even though they are post-war they are probably closer to wartime than the way maintenance is performed today. Aircraft that routinely spend time on the ground owing to defects suddenly arising are naturally regarded as being less reliable, and again it depends on various factors. The equipment fitted, like for example the Darne guns had their own reliability issues, which affected the aircraft's serviceability.
The concept of LRUs is not a new one but has certainly been refined and made easier compared to wartime. Each rotable unit today has its own time between overhaul and this record is kept separate to aircraft maintenance schedules, so even while in service and in the middle of a run, an aircraft can be taken off the line for replacement of an LRU at any time as these have regulatory expectations to be met. This is usually recorded on their CAA Form 1 documentation, which gives serviceability info.
As for what levels of maintenance do we use is a moot question. Knowing and understanding each system of maintenance is the key and that might not be translatable between armed services. I certainly can't add any more to that as I simply don't know the answer. The table that Mike provided is a good insight as to how the RAF did it.
Organisations can certainly chop and change when maintenance is done to an aircraft, as long as it meets the criteria as stipulated in the maintenance manuals. If the manuals state the aircraft are to have 100 hour servicings, then this needs to happen. The organisation might wish to separate each task out into individual jobs spread out over time or at different bases, but as long as the work is done in accordance with the manual and its TBO stipulations.
Those are good questions and directly pertaining to the A6M offers a different scenario to, say, even F4Fs and F6Fs at jungle strips simply because of the logistical situations arising between each of the forces. I couldn't answer directly about rates of serviceability for the Zero, certainly unit availability rates can assist with that, if anyone has pertinent figures. Again, this is where environment and quality of engineers come into the fold. In situations where logistics dries up, more inventive means of coping with that situation have to be taken into account. Iran keeping F-4s, F-5s and F-14s serviceable despite a dearth of parts is an example of this. Using the Hawk SAM instead of AIM-54s is an imaginative solution to a thorny issue, and for the IRIAF, it appears to suit its needs.
Using canabalised parts is an obvious and often necessary measure and I've seen it done by airlines even today. We used to often park aircraft that were awaiting parts from overhaul facilities outside our base and use them as parts trees if we didn't have what we needed in store to get another aircraft back on the ramp for the next morning. These days there are regulatory issues surrounding that, as everything has to be traced and every step we make has to be made in accordance with some piece of legislation, but during the war on a coral atoll, I reckon the regulations might not have played such a decisive role. You can guarantee that parts were canabalised from spares trees based on the logistical availability of parts.
I'm not so knowledgeable of US Navy practise, but common knowledge/perception (?) is that US aircraft were a little more expendable, or should I say in riposte, other air forces were a little more attentive regarding the recovery of downed aircraft and parts - again, a perception rather than a fact? I remember reading a personal account of action by an RAF unit in Europe post Overlord, the individual commented on a wrecked P-47 he had seen sat forlorn for ages at the FOB he was at, and he wondered whether or not it was going to be removed for spares. The US and its industrial might certainly had options, but I wouldn't want to say the US forces were less careful regarding airframe serviceability because they had the option to leave aircraft because there were ten more arriving by boat next week, so to speak. Some of our other members might be able to elaborate more on US military policy regarding this during the war. The US had maintenance ships that were parked at strategic locations offshore from battlefield theatres that were outfitted with workshops specifically for the maintenance and overhaul of components, which was a clever idea.
Yup, Blade repair obviously is measured and even during the war was done in accordance with the maintenance manuals, which outlined tolerances. Those aluminium props could take quite a beating and I've seen the extent that they can be straightened if bent. Servicing the hubs is like any component, really, high tolerances and measurements taken with Mitutoyo gauges and DTIs in a sterile workshop environment. When I worked in a prop shop, we had to dismantle and inspect props from aircraft that had been involved in accidents, mainly to determine if prop failure was a contributory factor in the accident's outcome. The policy today is that no component from a crashed propeller can be re-used, even if it passes tolerance testing. That is certainly a luxury that wartime engineers didn't have, so again serviceability is dependent on the manuals, which even back then were very detailed and specific.
As for man-hours as a quantifiable measure, it depends on the facility, what the manuals state, which'll differ between prop manufacturers, experience levels, and spares availability and so on. As mentioned before, efficiency or lack of is measured using various yardsticks. If you can retrieve such figures for individual props in a wartime setting, I think you might be lucky.
So, in summary, a key to this is understanding the maintenance structure within an organisation or service. Understanding the premise that aircraft require maintenance and the types of maintenance required is important. The foundation of aircraft maintenance is the humble inspection and carrying these out on a frequent basis is decided by the aircraft manufacturer, which ultimately decides an aircraft's maintenance schedule within an organisation.
There's a difference between scheduled and unscheduled maintenance. The former is planned inspections based on time in service, during which defects are found and work arising from those inspections determines how much time the aircraft can spend on the ground. These are your alphabet checks in airline parlance and your '100 hour' servicings and so forth. Unscheduled maintenance is stuff that happens, a burst tyre, stone damage to a fuselage or wing, bird strike etc, which all has to be fixed at some stage or another, requiring the aircraft to be taken off the line.
I hope that helps a bit.
Regarding maintenance hours, yes, that's a good measure of reliability, or more relatably time spent on the ground. Using my own experience, which doesn't equate to the same as WW2 aircraft maintenance, but might help contextually, airlines make money when their aircraft are in the air, so having them on the ground undergoing maintenance is anathema to their very existence, hence why line maintenance is done at night between day operations. Heavy maintenance is a fact of life and affects aircraft availability, the schedules that Mike Meech provided give us a good clue as to aircraft servicing times for the RAF, even though they are post-war they are probably closer to wartime than the way maintenance is performed today. Aircraft that routinely spend time on the ground owing to defects suddenly arising are naturally regarded as being less reliable, and again it depends on various factors. The equipment fitted, like for example the Darne guns had their own reliability issues, which affected the aircraft's serviceability.
The concept of LRUs is not a new one but has certainly been refined and made easier compared to wartime. Each rotable unit today has its own time between overhaul and this record is kept separate to aircraft maintenance schedules, so even while in service and in the middle of a run, an aircraft can be taken off the line for replacement of an LRU at any time as these have regulatory expectations to be met. This is usually recorded on their CAA Form 1 documentation, which gives serviceability info.
As for what levels of maintenance do we use is a moot question. Knowing and understanding each system of maintenance is the key and that might not be translatable between armed services. I certainly can't add any more to that as I simply don't know the answer. The table that Mike provided is a good insight as to how the RAF did it.
Organisations can certainly chop and change when maintenance is done to an aircraft, as long as it meets the criteria as stipulated in the maintenance manuals. If the manuals state the aircraft are to have 100 hour servicings, then this needs to happen. The organisation might wish to separate each task out into individual jobs spread out over time or at different bases, but as long as the work is done in accordance with the manual and its TBO stipulations.
Those are good questions and directly pertaining to the A6M offers a different scenario to, say, even F4Fs and F6Fs at jungle strips simply because of the logistical situations arising between each of the forces. I couldn't answer directly about rates of serviceability for the Zero, certainly unit availability rates can assist with that, if anyone has pertinent figures. Again, this is where environment and quality of engineers come into the fold. In situations where logistics dries up, more inventive means of coping with that situation have to be taken into account. Iran keeping F-4s, F-5s and F-14s serviceable despite a dearth of parts is an example of this. Using the Hawk SAM instead of AIM-54s is an imaginative solution to a thorny issue, and for the IRIAF, it appears to suit its needs.
Using canabalised parts is an obvious and often necessary measure and I've seen it done by airlines even today. We used to often park aircraft that were awaiting parts from overhaul facilities outside our base and use them as parts trees if we didn't have what we needed in store to get another aircraft back on the ramp for the next morning. These days there are regulatory issues surrounding that, as everything has to be traced and every step we make has to be made in accordance with some piece of legislation, but during the war on a coral atoll, I reckon the regulations might not have played such a decisive role. You can guarantee that parts were canabalised from spares trees based on the logistical availability of parts.
I'm not so knowledgeable of US Navy practise, but common knowledge/perception (?) is that US aircraft were a little more expendable, or should I say in riposte, other air forces were a little more attentive regarding the recovery of downed aircraft and parts - again, a perception rather than a fact? I remember reading a personal account of action by an RAF unit in Europe post Overlord, the individual commented on a wrecked P-47 he had seen sat forlorn for ages at the FOB he was at, and he wondered whether or not it was going to be removed for spares. The US and its industrial might certainly had options, but I wouldn't want to say the US forces were less careful regarding airframe serviceability because they had the option to leave aircraft because there were ten more arriving by boat next week, so to speak. Some of our other members might be able to elaborate more on US military policy regarding this during the war. The US had maintenance ships that were parked at strategic locations offshore from battlefield theatres that were outfitted with workshops specifically for the maintenance and overhaul of components, which was a clever idea.
Yup, Blade repair obviously is measured and even during the war was done in accordance with the maintenance manuals, which outlined tolerances. Those aluminium props could take quite a beating and I've seen the extent that they can be straightened if bent. Servicing the hubs is like any component, really, high tolerances and measurements taken with Mitutoyo gauges and DTIs in a sterile workshop environment. When I worked in a prop shop, we had to dismantle and inspect props from aircraft that had been involved in accidents, mainly to determine if prop failure was a contributory factor in the accident's outcome. The policy today is that no component from a crashed propeller can be re-used, even if it passes tolerance testing. That is certainly a luxury that wartime engineers didn't have, so again serviceability is dependent on the manuals, which even back then were very detailed and specific.
As for man-hours as a quantifiable measure, it depends on the facility, what the manuals state, which'll differ between prop manufacturers, experience levels, and spares availability and so on. As mentioned before, efficiency or lack of is measured using various yardsticks. If you can retrieve such figures for individual props in a wartime setting, I think you might be lucky.
So, in summary, a key to this is understanding the maintenance structure within an organisation or service. Understanding the premise that aircraft require maintenance and the types of maintenance required is important. The foundation of aircraft maintenance is the humble inspection and carrying these out on a frequent basis is decided by the aircraft manufacturer, which ultimately decides an aircraft's maintenance schedule within an organisation.
There's a difference between scheduled and unscheduled maintenance. The former is planned inspections based on time in service, during which defects are found and work arising from those inspections determines how much time the aircraft can spend on the ground. These are your alphabet checks in airline parlance and your '100 hour' servicings and so forth. Unscheduled maintenance is stuff that happens, a burst tyre, stone damage to a fuselage or wing, bird strike etc, which all has to be fixed at some stage or another, requiring the aircraft to be taken off the line.
I hope that helps a bit.
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All of the above and more, I'd say, including the pace of repair and overhaul as affected by these factors. There's no single factor that warrants that Hurricanes were easier to maintain. Part of the problem that arises that hasn't been given much airtime here is individual bias. Engineers are human, and like the Luftwaffe pilots that were averse to acknowledging they got shot at by Hurricanes, they'll have their biases based on their experiences.
Geoffrey Sinclair
Staff Sergeant
- 777
- Sep 30, 2021
The obvious.
Given the amount of poor quality information around about the Hurricane, includuding the "Mk.Is often ended up as Mk.IIs after a repair/rebuild" ideas, engine fits and so on, I discount anything unless it is backed by original documents. In any case quicker overhaul now becomes more were done? More done is to be expected. The question being what resources were needed to do this and whether they were quicker.
When combined with production deliveries for the time period the output of the repair system was 27.14% of Hurricane supply and 27.41% of Spitfire. The repair system, in output terms, was in step with production. The RAF had a big spare parts problem in 1940/41, so was the supply of Spitfire and Hurricane specific parts equivalent, there was no priority one way or the other for common items, nor any priority of one type over another for workers? Given the distribution of squadrons was the average Spitfire flying more or less, more or less exposed to combat damage? All that will effect total needs and output.
When it comes to claims the Hurricane had easier maintenance that requires some sort of measurement, it had lots of common parts with the Spitfire, but was, for example, the Spitfire hydraulic system more/less complex and easier/harder to service? People talk about hits on the rear fuselage, what about damage to wing surfaces, any difference in repair/maintenance effort between the two different types? And so on.
One of the hidden factors in counting Battle of Britain strength ratios is that 30 Hurricane squadrons spent until early September with establishments of 22 aircraft, the remaining Hurricane and all Spitfire squadrons establishments were 18, 30x4 is the equivalent of nearly another 7 Hurricane squadrons, if they actually managed to have the aircraft.
The loss figures are there because of the Hurricane was more rugged claims. Yet a greater percentage of Hurricanes hit by enemy fire were lost using the Bungay figures, while the other set of figures says 1.1 Spitfires were damaged for every one lost, versus 0.84 Hurricanes damaged per loss. So how do these results fit the more rugged idea? Both airframes would have the same designed strength factors.
FLYBOYJ
"THE GREAT GAZOO"
Scheduled maintenance and repairing battle damage are two different animals. Scheduled maintenance is a known given, the procedures will be the same to the point where you can estimate the manhours for the task. Any type of damage to the aircraft to include battle damage is an unknown until the airframe is thoroughly inspected.
Having maintained aircraft for a number of years and having the opportunity to see Spitfires and Hurricanes in person, I'd say much of the airframe servicing (such as the hydraulic system) is similar if not the same.
ThomasP
Senior Master Sergeant
As I have mentioned in other threads, the Hurricane is my favorite fighter from WWII, so I have spent more time on research of it than on other aircraft. This does not make me a "Hurricane expert' but it gives you an idea where I am coming from.
From what I have read, the structure of the tube frame/Warren-truss structure was more 'rugged' than the monocoque structure of the Spitfire, but also heavier. As mentioned above both airframes were built to the same basic minimum load requirements, so what this implies if anything I can not say. However, many anecdotal and semi-official records have the commentators describing the Hurricane airframe as 'rugged' as opposed to almost none for the Spitfire (at least the ones I have run across). Do not misunderstand, they do not say that the Spitfire structure is weak or anything like that, just that there is no comment on the matter. IIRC there is occasionally mention of problems with the Spitfire landing gear, particularly at rough airfields.
As mentioned upthread, the fabric covered wood aerodynamic shell and steel tube frame of the rear fuselage on the Hurricane would allow a low(er) angle deflection projectile to pass through and reach the pilot armour and equipment in the rear, maybe the control linkages/runs, as well as the pilot in some circumstances, more easily than if it had to pass through the aluminum skinning on the Spitfire. This is a matter of physics and ballistics so I do not think there is any argument there?
Although I have read official documents stating that the turn-around time was quicker for the Hurricane, I have not run across any official documentation that said the routine maintenance was any quicker. The only comments that might apply are that some systems were easier to access in the Hurricane. (This last is from a pre-war comparison of the Hurricane and Spitfire by the RAE/A&AEE, which covered ease of maintenance and turn-around times.)
The only major area that I have found official mention of (where the Hurricane was clearly superior to the Spitfire) was in the area of repair of damage. There are several official reports (including at least one posted online) that indicate that a significantly larger % of Hurricanes could be repaired at the squadron level than the Spitfire, and at the next level of repair (I am sorry but I do not remember the term right now for the other levels of facility) than the Spitfire. In effect, more Spitfires had to be transported to the rear for repair. Even if only the time for the transport is taken into account then this would make the Spitfire more time intensive to repair. During the Bob where supply lines were relatively short this might not have made too much difference to the availability rates, but in the MTO, CBI, and PTO, this could have had a significant effect.
I do not remember the exact numbers, but IIRC the Spitfire had to be sent to the rear for repair about twice as often as the Hurricane. Possibly someone has records with such information for multiple squadrons of each type, but I only have general and/or short term records for a couple of Hurricane Sqn and one Spitfire Sqn, and that is too little I think to make any authoritative conclusion from.
From what I have read, the structure of the tube frame/Warren-truss structure was more 'rugged' than the monocoque structure of the Spitfire, but also heavier. As mentioned above both airframes were built to the same basic minimum load requirements, so what this implies if anything I can not say. However, many anecdotal and semi-official records have the commentators describing the Hurricane airframe as 'rugged' as opposed to almost none for the Spitfire (at least the ones I have run across). Do not misunderstand, they do not say that the Spitfire structure is weak or anything like that, just that there is no comment on the matter. IIRC there is occasionally mention of problems with the Spitfire landing gear, particularly at rough airfields.
As mentioned upthread, the fabric covered wood aerodynamic shell and steel tube frame of the rear fuselage on the Hurricane would allow a low(er) angle deflection projectile to pass through and reach the pilot armour and equipment in the rear, maybe the control linkages/runs, as well as the pilot in some circumstances, more easily than if it had to pass through the aluminum skinning on the Spitfire. This is a matter of physics and ballistics so I do not think there is any argument there?
Although I have read official documents stating that the turn-around time was quicker for the Hurricane, I have not run across any official documentation that said the routine maintenance was any quicker. The only comments that might apply are that some systems were easier to access in the Hurricane. (This last is from a pre-war comparison of the Hurricane and Spitfire by the RAE/A&AEE, which covered ease of maintenance and turn-around times.)
The only major area that I have found official mention of (where the Hurricane was clearly superior to the Spitfire) was in the area of repair of damage. There are several official reports (including at least one posted online) that indicate that a significantly larger % of Hurricanes could be repaired at the squadron level than the Spitfire, and at the next level of repair (I am sorry but I do not remember the term right now for the other levels of facility) than the Spitfire. In effect, more Spitfires had to be transported to the rear for repair. Even if only the time for the transport is taken into account then this would make the Spitfire more time intensive to repair. During the Bob where supply lines were relatively short this might not have made too much difference to the availability rates, but in the MTO, CBI, and PTO, this could have had a significant effect.
I do not remember the exact numbers, but IIRC the Spitfire had to be sent to the rear for repair about twice as often as the Hurricane. Possibly someone has records with such information for multiple squadrons of each type, but I only have general and/or short term records for a couple of Hurricane Sqn and one Spitfire Sqn, and that is too little I think to make any authoritative conclusion from.
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FLYBOYJ
"THE GREAT GAZOO"
And I think you'll find that arming the aircraft was the major time consumer on both Spitfire and Hurricane.
Geoffrey Sinclair
Staff Sergeant
- 777
- Sep 30, 2021
Two sets of data. From Wood and Dempster, the Narrow Margin, Appendix 15. The losses exclude destroyed or damaged on ground. Unfortunately no Category 1 figures in the book. Category 1, repair in unit, Category 2 repair beyond unit capacity, Category 3 total loss, Category 3m total loss, missing.
| Type | Hurricane | Hurricane | Spitfire | Spitfire |
| Damage Category | Cat 2 | Cat 3 | Cat 2 | Cat 3 |
August 1940 | ||||
| combat | 49 | 220 | 55 | 118 |
| accident | 38 | 18 | 35 | 14 |
September 1940 | ||||
| combat | 95 | 228 | 80 | 130 |
| accident | 60 | 21 | 56 | 13 |
| Totals | ||||
| combat | 144 | 448 | 135 | 248 |
| accident | 98 | 39 | 91 | 27 |
| Total | 242 | 487 | 226 | 275 |
A study in the late 2000's using archive material. The period is 8 August to 30 September 1940, where an attempt was made to reconcile all discrepancies and, since it was an USAF contract effectively, eliminate all losses that were not due to air-to-air actions, meaning aircraft destroyed on the ground are not included.
| British | Cat 1 | Cat2 | Cat3 | Cat3m |
| Blenheim 1F | 14 | 4 | 6 | 15 |
| Defiant | 3 | 8 | 6 | 9 |
| Beaufighter | 1 | 0 | 1 | 0 |
| Hurricane Mk I | 166 | 200 | 98 | 386 |
| Hurricane Mk II | 1 | 1 | 1 | 1 |
| Spitfire IB | 2 | 0 | 0 | 3 |
| Spitfire IA | 85 | 171 | 76 | 183 |
Almost as many Spitfires were removed from units for repair as Hurricanes, or nearly twice as many relative to force sizes, that ratio is not proof the Spitfire was significantly harder to repair in 1940 given the lack of information on squadron repair abilities, the wide variety of damage being taken and an overall lower loss ratio damaged to destroyed.
No information on whether as Spitfire and Typhoon became the standard fighters the RAF gave squadrons a greater ability to repair stressed skin aircraft.
For completeness, the second study German losses
| Germans | 1-39% | 40-59% | 60-99% | 100% |
| BF109 | 82 | 36 | 64 | 375 |
| Bf 110 | 37 | 19 | 24 | 183 |
| Do17Z | 41 | 15 | 20 | 100 |
| Do18 | 0 | 0 | 1 | 4 |
| Do 215 | 0 | 0 | 0 | 5 |
| Do 24 | 0 | 0 | 0 | 1 |
| Unknown Fighter | 1 | 0 | 0 | 0 |
| Fw 200 | 1 | 0 | 0 | 1 |
| Go 145 | 0 | 0 | 0 | 1 |
| He 111 | 48 | 29 | 18 | 152 |
| He 115 | 0 | 0 | 0 | 10 |
| He 59 | 1 | 1 | 0 | 13 |
| Hs 126 | 0 | 4 | 3 | 1 |
| Ju 87 | 18 | 10 | 7 | 61 |
| Ju 88 | 60 | 37 | 28 | 163 |
