When it comes to changing a damaged wing a Spitfire is certainly harder to repair than a Hurricane. With a Hurricane the wing outboard from the undercarriage can be replaced using muscle power and the tools required to unfasten and fasten it. With a Spitfire you need a crane and tools especially if the spar is damaged, it goes through both wings.
Least resource intensive/easy to maintain aircraft of WW2?
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Callsign WW2RDO
Recruit
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- Jul 20, 2022
Least resource intensive WW2 Airplane? That's easy ! CG-4-A glider
The reality is that such things cannot always be measured through figures alone. As I have mentioned, reliability of a type is not a simple metric to assign a figure to and it depends on so many factors. Let's not forget that the Spitfire and Hurricane's wings, tail and hori stabs were the same construction, it was only the fuselages that were different. Regarding parts, supply and availability are issues that need to be considered and commonality is certainly a thing, but it is how and where the common parts are located in the airframe, but again, it depends on what you are referring to. Line servicing is very different to what is called "Depot level' servicing, where the aircraft are sent away for major work done to them, so context has to be taken into ccount.
They don't inform about reliability of maintenance though, so their application here serves no real purpose. As Joe highlighted, damage repair is a separate issue to scheduled maintenance that might inform reliability statements. Damage repair, regardless of type is a skill applied by structural engineers skilled in such things and isn't necessarily done by the same maintenance team or 'gang' as the guys who arm the aircraft and fill type pressures and so forth. Overhaul is a separate issue and again, isn't the same as scheduled maintenance. Aircraft have a schedule under which they have to undergo maintenance. Damage repair counts as unscheduled maintenance, which, as I mentioned is stuff that happens to the airframe through operational use.
I wouldn't rely on Wood and Dempster's figures too closely, they have almost certainly been superceded as the book was published more than 50 years ago.
FLYBOYJ
"THE GREAT GAZOO"
100% Some folks can't grasp that REPAIRING an aircraft and ROUTINE MAINTENANCE are two different animals!!!
You can publish all the charts and graphs you want, to answer the mail on the OP's original question, "Least resource intensive/easy to maintain aircraft of WW2?" you have to separate ROUTINE OR PREVENTATIVE MAINTENANCE!!!
Here's an internet definition:
Essentially, this is any work performed from a list of permitted tasks where you're replacing small standard parts or servicing parts of the aircraft without taking much apart. Aircraft preventive maintenance typically takes place on a regular schedule and aims to prevent major problems through upkeep.
FLYBOYJ
"THE GREAT GAZOO"
Actually you make a great point!
Geoffrey Sinclair
Staff Sergeant
- 932
- Sep 30, 2021
Reliability can be a synonym for serviceability which is measured all the time, also the abort rates, again measured all the time. Which is different to resouces required to achieve a given level. Manuals on what maintenance is required, when and how much effort is required do that, plus the costs of spare parts, since ease includes paying for everything, dropping something like a replacement radio in can be "easier" than spending the time testing and diagnosing a problem.
Ease of damage repair requires the accounting of the effort in repairing large enough numbers of damaged airframes to smooth out all the variables in what damage was taken. Then comparison with other types. That covers the mechanical engineering. It still has to note the "ruggedness", if one type was better able to return with damage than another.
The definitions of line servicing and depot servicing are not useful in finding out resources/easy maintenance issues. The hours and parts required for each type of service would be measured, those figures are required.
For the Hurricane and Spitfire in 1940 all we have is the numbers of damaged aircraft retained by the units versus set away for repairs, with no idea about any different thresholds for different aircraft types. If most Hurricane squadrons were resourced for 22 aircraft, then cut to 18 in early September does that mean a better serviceability rate on average versus the 18 strength Spitfire squadrons? As strength was cut it implies a problem in keeping either aircraft strengths or serviceability in the larger units. Did the average Hurricane squadron have more maintenance personnel and resources per aircraft than the average Spitfire one? A better or worse spare parts problem?
On loss figures,
Yet ruggedness is also a synonym for ease of maintenance, the rugged bush aircraft, able to keep going when others cannot, accept hand landings, while being cheap to run. In any case note how many times rugged has been mentioned already and as noted rugged does play a part in determining things like the total loss to damaged ratio and therefore maintenance/repair loads separate from the new production requirements.
Where does this come from? What age does the book have to be before we can rely on the figures? Wood and Dempster (first edition in 1961, the edition I am quoting from is from 1969) were able to obtain access to data not yet available to the general public, it means their data is over 80 years old. Has there been a major recalculation of the RAF lost and damaged finding major flaws in what the RAF was telling itself? Are you claiming the authors did their own calculations rather than reproducing the official statistics? Also I have given two other sets of data, which are more modern, all 3 sets are consistent.
Consider how the Hurricane was rated as the better gun platform, it did not move nearly as much as the Spitfire when the guns were fired, and how this might make pilots decide which airframe was more "rugged".
FLYBOYJ
"THE GREAT GAZOO"
Errr, no - I don't know if you ever worked around aircraft as it seems you're inventing your own definitions. Serviceability is defined as the amount of effort it takes to perform a maintenance task. If it takes me an hour to change the brakes on aircraft "A" and two hours to change the brakes on aircraft "B" it's obvious which aircraft has better serviceability for that task. Compare the entire maintenance schedule of two aircraft (ex. Spitfire/ Hurricane) and that will give you an indication which aircraft has "better serviceability."
Reliability - in laymen's terms (something you should use more) is the ability of an aircraft to make it to it's next inspection/ maintenance schedule without having something break (excluding battle damage if we're discussing combat aircraft)
You're convoluting several maintenance functions into one. Cost factor of "Rotable Parts" (look up the definition) and other components are factored in to a sustainment cost. This can be determined on the SCHEDULED maintenance performed as most if not all maintenance manuals are going to tell you what rotables, filters, hardware is going to be changed during SCHEDULED maintenance. Your example on troubleshooting a radio WOULD NOT be considered scheduled maintenance!!!
Again, repairing damage, be it from combat, wear and tear or operational damage is different matter.
And again you're 100% incorrect. Scheduled maintenance tasks can and were quantified to the point where it can be predicted exactly how long it would take to perform planned inspections and maintenance. This was the case during WW2 and is the norm today. Now anything found outside of SCHEDULED maintenance would be considered a REPAIR (in certain organizations referred to as "non-routine" or "over-and-above" tasks). All of this includes scheduled maintenance at the line and depot level.
Again, I don't know if you have any experience in this area, but there are several of us here who have been actively engaged in aircraft maintenance for many years and worked under these conditions, both as civilians and members of the military.
FLYBOYJ
"THE GREAT GAZOO"
Below is a maintenance job sheet for the B-24. It seems this was developed for aircrew training but I'm sure a similar if not the same sheet would be used at the unit level.
What is shown are ROUTINE maintenance tasks. The time it takes to complete these tasks can easily be determined as they are repetitive providing no issues are found. Now if a discrepancy is found, then it is/was written up on a AAF Form 1 (781A in today's world) I couldn't find an original Form 1 but it was very similar to the 781A used today.
I hope this further clarifies the difference between routine/ scheduled maintenance and non-routine repairs, at least in the AAF. I am not sure what the RAF used but it wouldn't surprise me if their processes were similar
What is shown are ROUTINE maintenance tasks. The time it takes to complete these tasks can easily be determined as they are repetitive providing no issues are found. Now if a discrepancy is found, then it is/was written up on a AAF Form 1 (781A in today's world) I couldn't find an original Form 1 but it was very similar to the 781A used today.
I hope this further clarifies the difference between routine/ scheduled maintenance and non-routine repairs, at least in the AAF. I am not sure what the RAF used but it wouldn't surprise me if their processes were similar
Barrett
Senior Airman
Gliders.
Shortround6
Major General
YES!!! put all the expensive parts of maintenance on somebody else's account/tab
Geoffrey Sinclair
Staff Sergeant
- 932
- Sep 30, 2021
So when a unit reports x% of its aircraft serviceable, how much effort does that represent? Your definitions of serviceability and reliability are at an individual aircraft level. Serviceability and reliability as I am using the terms above is at the unit level, what % of the force can be usually expected to be available day to day, how many abort missions because of faults.
Agreed, I was actually but unclearly pointing out how you can cost and effort shift depending on what is important, dropping a new radio in as a time saver if you want to turn the aircraft around, as is sending aircraft away and receiving new ones to keep the load down on the unit but serviceability up. Everyone has encountered the better way of doing things that has been stopped because it costs shifts onto someone powerful enough to resist the change. The fighter pilot congratulating himself on returning his badly damaged fighter met with the maintenance crew pointing out that means they have to fix it instead of receiving a new one.
Wear and tear is damage, versus being part of routine maintenance? Apart from damage there is what a squadron can expect to take care of during routine operations and what happens in an emergency. The Battle of Britain was an emergency situation but all we have is data showing the numbers of damaged aircraft repaired by the combat units or taken away to be repaired in a situation where the operational airfields were taking damage, degrading their ability to perform maintenance, and risking the safety of leaving aircraft there to await maintenance, with aircraft taking all sorts of damage amounts, where it seems Hurricane squadrons were on average bigger than Spitfire ones and probably other factors as well.
Can you please reread my words? And note you are essentially agreeing with me while saying I am wrong? In particular my second sentence? I was pointing out giving a definition do not help finding what resources are required and therefore the ability to find one type was more reliable, rugged, better nose art or whatever.
Why add the mention of repair, which by definition tends to be non scheduled, in "line servicing and depot servicing"? So something unexpected, the need for a repair, can be scheduled?
Will this help?
All machines have regular scheduled maintenance making it easy to compare the costs, ultimately in money but also the times between maintenance and the time required for the work. Sometimes the scare or more valuable commodity is time, others money.
Next is damage repair, which in this case is about Hurricane versus Spitfire, with only anecdotal evidence about damage to specific parts of the airframe. Before you even start on the repairs accounting you need to check whether one type or the other could make it back with on average heavier damage than the other. Something which tends to be called rugged.
Apart from similar forms/checklists. The RAF went to planned flying, which was efficient in its use of maintenance personnel at the expense of breaking the direct link between them and an individual aircraft which had its costs.
The USAAF has far more detailed figures published on issues like accident and loss rates, serviceability and abort rates than the RAF. So 1,018 out of 4,228 8th Air Force B-17 losses on operations were Category E, 24.1%, while 544 out of 1,562 8th Air Force B-24 losses on operations were Category E, 33.4%. On that basis the B-24 was more rugged, more chance of returning with write off levels of damage.
When it comes to accidents they include things like being hit while parked, the ground crew setting the aircraft on fire as well as take off accidents, collisions, etc. The USAAF usually classified the damage taken between 1, minor, and 5 salvaged/write off. As far as I can tell some level 3 and most level 4 damaged aircraft were scrapped. The B-17 accident list I know of has 4,021 accidents, 3,632 of which have a 1 to 5 damage level recorded, 27% level 4, 23% level 5. For the B-24 3,653 accidents, 3,288 of which have a damage level recorded, 35% level 5, 30.4% level 4. So 50% of B-17 accidents probably meant scrapping versus 65.4% of B-24 accidents.
That says the B-24 was at least more likely to sustain greater damage in an accident. And heavily damaged aircraft returning tend to make crash landings or be abandoned in the air if the landing risk was judged too great. So how much of the higher percentage B-24 of making it back with write off damage is actually due to on average taking more damage during the landing? Accidents percentage B-17 50.0, B-24 65.4, 8th AF category E percentage times two B-17 48.2, B-24 66.8
On this evidence, which was the more rugged? That is able to take more damage but make it home? To remove the effects of the 1943 losses, for 1944 only 20.4% B-17 losses were write offs, 28.7% B-24, loss rates B-17 2.0%, B-24 1.8% of credit sorties.
It is a question with an answer, but the question is like which football player is the best at chess? No one cares! What is a resource? The pilot is the most valuable resource in the airforce so the plane that preserves pilot life is the most desirable. Use of materials, fuel and engines may have been something that had to be coped with but no one was going to replace Malta's Gladiators with more Gladiators. Malta got Hurricanes and then Spitfires. The humble Hurricane, started life with dope wings that were replaced with metal skinned wings, so the early versions had two sets of wings, just as they had two props, some may even have had three if they survived long enough, a twin blade wooden one, a three blade variable pitch and a three blade C.S. They were switched to 100 Octane fuel, this was a huge effort, not only the development and testing of the engines and fuel which cost more, but setting up a new supply and storage chain everywhere Hurricanes and Spitfires were used. All of this was done without any real care of cost, because if you didnt do it then you may as well give up the fight. By 1939-40 the humble Hurricane was just a small part of a huge effort, there were tens of thousands of people involved in making and flying them, making and operating Chain Home, operating the CAC Dowding system and its mass of telephone and teleprinter connections, The Royal Observer Corps, all the airfield staff and people constructing and developing new airfields, concreting runways etc. Against that, what did it matter how much fuel or metal a Hurricane used?
You would think so, but I was just reading yesterday that in the run up to D-Day lots of gliders had been made and stored for a long time, some were getting worried that they may be going mouldy with damp or eaten by insects and vermin. How expensive is a single use item, that you cant use?
FLYBOYJ
"THE GREAT GAZOO"
"Effort?" You're asking for an enigma. It depends on how many aircraft are in the unit, what scheduled maintenance is due and how many aircraft are "mission capable," (term is mentioned below)
Nope - it's at the individual aircraft level. You can have two aircraft of the same type (say two single engine fighters). One may take 3 days to do a planned phased inspection, the other may take 4.
See what I posted above when you want to talk about aircraft at the unit level.
You determine available aircraft to conduct a certain mission based on maintenance required and those aircraft that are broke. Some of this is determined by some equipment that is allowed to be non-operational as opposed to being full functional. The terms are "Mission Capable" and "Fully Mission Capable."
"Mission Aborts" cannot be normally predicted as you don't have a crystal ball to predict something that is going to happen in the future, however if you're large fleets of aircraft flying on a regular basis, you can probably come up with a statistical average. When you schedule 10 aircraft for a mission, the plan is to have 10 aircraft fly.
Again, this is apples and oranges - Repairs vs Scheduled Maintenance.
No - wear and tear is EXPECTED. That's why some components and in some cases parts of the airframe actually have a "shelf life" where you change out the whole unit based on an hourly or cycle requirement.
Again - you're talking REPAIR (and in the case of the BoB repair from battle) vs Scheduled Maintenance.
I re-read your words and so far you seem not to understand that scheduled maintenance is a known factor. It is defined and can be measured to include parts and manpower, something you cannot do when addressing DAMAGE, be it from combat or aircraft abuse/ accident
No because once again you're not grasping this, probably because you never worked or been around this environment. Again a repair is a non scheduled maintenance action. Can you schedule a repair into scheduled maintenance? Sure - but in doing so it is not a measure of how "serviceable" the given aircraft really is!
Agree - see my comments above
OK...
Again, ok...
I am well aware of how the USAAF classified mishaps and in my previous posts I've showed how it evolved in to the mishap rating system, you're posting meaningless numbers that have absolutely no bearing here as you're convoluting maintenance into operational statistics and still discussing "unscheduled maintenance" into the fray. You can't wrap your head around the fact that Scheduled Maintenance is a known quantity - a maintenance planner, scheduler or maintenance officer can accurately determine to a great degree how long a scheduled maintenance activity (Phase inspection. hourly inspection, etc.) is going to take. Damage repair, especially combat damage is an unknown until the aircraft can be inspected and a repair can be determined. I'll repeat again - this is OUTSIDE the scope of scheduled maintenance.
So please - understand once again that some of us have actually worked in this environment and some methodology of determining aircraft serviceability has not changed in 80 years. While you are very good about putting together facts and statistics, your lack of real world experience is evident.
SaparotRob
Unter Gemeine Geschwader Murmeltier XIII
That's a problem I run into. Proper terminology. I'm familiar with the differences between repair and scheduled maintenance. I worked with Yardmasters (the railroad equivalent to an E-8, methinks) and was involved in moving equipment around for both services.
I am intrigued by the scheduling of nose art evaluations, though.
I am intrigued by the scheduling of nose art evaluations, though.
Hi
Dowding's Battle of Britain Despatch has a mention on servicing and the repair organization:
So to aid maintenance with the aircraft dispersed around the airfield 'tents' were used to help the ground crew (also seen in the Battle of France). To prevent the build up of damaged aircraft at operational airfields the aircraft concerned would have to be flown direct to a repair depot or transported by road, not kept in 'vulnerable' hangars on the airfield.
Other statistics and chart from the AHB Narrative of BoB:
Mike
Dowding's Battle of Britain Despatch has a mention on servicing and the repair organization:
So to aid maintenance with the aircraft dispersed around the airfield 'tents' were used to help the ground crew (also seen in the Battle of France). To prevent the build up of damaged aircraft at operational airfields the aircraft concerned would have to be flown direct to a repair depot or transported by road, not kept in 'vulnerable' hangars on the airfield.
Other statistics and chart from the AHB Narrative of BoB:
Mike
FLYBOYJ
"THE GREAT GAZOO"
And the problem is you have folks who read all about aircraft maintenance through various publications and many times you have authors writing about this stuff who never been around aircraft, let alone twisted wrenches or smacked rivets.
Although terminology has evolved over the years, the distinction between scheduled aircraft maintenance and aircraft repair is very evident. The current directive for the USAF AFI 21-101 is very descriptive and really gets into the weeds on how maintenance is conducted, repairs are completed and how operational maintenance is conducted.
In my day the terms "MC" and "FMC" were the norm. In today's world, these are the definitions for aircraft serviceability:
Code 0 - Ground abort.
Code 1 - Aircraft mission capable with no additional discrepancies.
Code 2 - Aircraft or system has minor discrepancies but is capable of further mission assignment within normal turnaround times.
Code 3 - Aircraft or system has major discrepancies in mission essential
equipment that may require extensive repair or replacement prior to further mission assignment. The discrepancy may not affect safety-of-flight and the aircraft may be Not Mission Capable (NMC) flyable.
Code 4 - Aircraft or system has suspected or known radiological, chemical, or biological contamination.
Code 5 - Aircraft or system has suspected or known battle damage.
I believe a majority of that would be done at the NCO club.
FLYBOYJ
"THE GREAT GAZOO"
And Mike, this is all good when addressing REPAIRS, especially when dealing with aircraft being flown in combat which is obvious. It's also evident that some scheduled maintenance will be undertaken at this time. The amount of time and effort it takes for repairs will obviously vary between aircraft and units. For example, I can have a training unit of 12 Spitfires of which 10 are flying at any given time and are just used for training, then I have another squadron of the same number experiencing heavy combat, it going to be quite obvious which unit was going to see more downtime, so to get a better picture of operations, you separate the normal SCHEDULED maintenance from the repairs and this will give you a true matrix of were you stand for both situations.
