Why the heck did they design it that way?

[michael rauls]

If I can throw in my 2 cents( and that may be exactly what it's worth). The idea of the spitfire being slow sounds a little odd to me. The early models had a speed of about 360 near as I can tell. Not a rocket exactly but can't think of alot of planes that were much faster in 40/41. If I remember right the later Griffin jobss were close to 450. Sounds pretty good to me. Certainly not what I would characterise as slow. Just my take.

 

[pbehn]

If I can throw in my 2 cents( and that may be exactly what it's worth). The idea of the spitfire being slow sounds a little odd to me. The early models had a speed of about 360 near as I can tell. Not a rocket exactly but can't think of alot of planes that were much faster in 40/41. If I remember right the later Griffin jobss were close to 450. Sounds pretty good to me. Certainly not what I would characterise as slow. Just my take.

That is exactly the point, not only 1940 but 1939. At the time of its introduction it was a competitive front line interceptor/fighter with anything allied or enemy in outright performance, this situation continued throughout the war with the exception of late 1941 thro' to 1942 with the Fw190 and later the jet age.

 

[MiTasol]

You also have to remember that when many of these aircraft were designed (pencils/pens put to paper) self sealing tanks, armor and BP glass were not required.
These added hundreds of pounds to fighters and often resulted in smaller fuel tanks. In some cases in 1940 the improvements in the engines barely kept pace with the increase in operational weight let alone allowed large increases in fuel storage. Radio equipment was also added. For the British IFF so their own planes would show up on the ground radar as friendly is an often overlooked change.

And to put that weight increase into perspective, starting June 1945 the RAAF with their P-51's removed the fuselage fuel tank when they installed the IFF and vice versa. As well as the unit itself you have to add the shelving and in some cases reinforce the structure that the shelf attaches to.

 

[fastmongrel]

The Royal Aircraft Establishment did a lot of testing on Spitfires with a view to increasing speed. Things like fitting an internal armoured glass screen gave iirc about 8mph extra, gloss paint 2 mph, removing the ice shield from the intake gave 4 mph, sanding panel joints 3 mph, flush fuselage rivets 2 mph. There was quite a list of things that added 1 or 2 mph. Eventually they got a fairly well used MkIX up from about 400 mph to about 425mph.

 

[MiTasol]

Another example of the effect of adding the SCR-695 IFF is covered in this post on Mustangs.
Zoukei Mura P-51D
This may look like a minor change but structurally and wiring wise it was far from.

 

[Ivan1GFP]

If I can throw in my 2 cents( and that may be exactly what it's worth). The idea of the spitfire being slow sounds a little odd to me. The early models had a speed of about 360 near as I can tell. Not a rocket exactly but can't think of alot of planes that were much faster in 40/41. If I remember right the later Griffin jobss were close to 450. Sounds pretty good to me. Certainly not what I would characterise as slow. Just my take.

Hello Michael Rauls,
My comment wasn't so much that the Spitfire was slow. It was that it was relatively slow for the installed power.
The point is that with enough power ANYTHING can be made quite fast.
Consider that a Spitfire needed a Griffon engine to reach the speed of a Merlin P-51B.
I will admit that comparison to the Mustang is a hard one to win because the Mustang had unusually good aerodynamics, but with a little hindsight, perhaps we should compare it against another contemporary airframe: The Messerschmitt 109 or Hispano Buchon.
There are a few flying today with Merlin engines. I believe they are flying with Merlin 45's which would make them about equivalent to a Spitfire Mk.V for engine power. By my understanding, they are a lot faster than a Spitfire Mk.V.

- Ivan.

 

[pbehn]

Hello Michael Rauls,
My comment wasn't so much that the Spitfire was slow. It was that it was relatively slow for the installed power.
The point is that with enough power ANYTHING can be made quite fast.
Consider that a Spitfire needed a Griffon engine to reach the speed of a Merlin P-51B.
I will admit that comparison to the Mustang is a hard one to win because the Mustang had unusually good aerodynamics, but with a little hindsight, perhaps we should compare it against another contemporary airframe: The Messerschmitt 109 or Hispano Buchon.
There are a few flying today with Merlin engines. I believe they are flying with Merlin 45's which would make them about equivalent to a Spitfire Mk.V for engine power. By my understanding, they are a lot faster than a Spitfire Mk.V.

- Ivan.

For someone who doesn't want to make the discussion about the Spitfire versus Mustang you manage to introduce the Mustang fairly early in every post. Comparison is easy, 1939 no Mustang 1940 no Mustang, 1941 No Mustang, 1942 Mustang Mk 1 appears after Spitfire Mk IX, 1943 Merlin P51 appears alongside Griffon Spitfire, 1944 Me262, Meteor and Tempest in service.

As for the Spitfire versus Buchon, another aircraft you have introduced while wanting to discuss the Spitfire, please advise where your "understanding" comes from?

Has the Mustang airframe with a Merlin Mk III and a fixed pitch two blade prop been evaluated to see if it could get airborne?

 

[michael rauls]

Hello Michael Rauls,
My comment wasn't so much that the Spitfire was slow. It was that it was relatively slow for the installed power.
The point is that with enough power ANYTHING can be made quite fast.
Consider that a Spitfire needed a Griffon engine to reach the speed of a Merlin P-51B.
I will admit that comparison to the Mustang is a hard one to win because the Mustang had unusually good aerodynamics, but with a little hindsight, perhaps we should compare it against another contemporary airframe: The Messerschmitt 109 or Hispano Buchon.
There are a few flying today with Merlin engines. I believe they are flying with Merlin 45's which would make them about equivalent to a Spitfire Mk.V for engine power. By my understanding, they are a lot faster than a Spitfire Mk.V.

- Ivan.

I understand your point and its a good one perhaps when it comes to fuel consumption per mile. But as far as outright performance wouldn't the airframe design capable of housing the high hp engine, using the resulting hp in an effective manner i.e. still able to maneuver well and be stable at the higher speeds, and by extension the verry engine itself an integral part of the design? Again I'm certainly no expert but thats how it looks to me.

 

[michael rauls]

If I could put it another way whatever gave a specific aircraft " performance" whether that be speed due in part to higher hp or say long range due to a laminar flow wing in part, arent all those things just part of the design and the performance is what it is as a result of all those factors and all those factors are part of the design by definition. I mean wouldn't saying any plane would be fast if you put a big engine on it be kinda like saying any plane could be long range if you slap a laminar flow wing on it. Again im no expert but just an observation.

 

[pbehn]

If I could put it another way whatever gave a specific aircraft " performance" whether that be speed due in part to higher hp or say long range due to a laminar flow wing in part, arent all those things just part of the design and the performance is what it is as a result of all those factors and all those factors are part of the design by definition. I mean wouldn't saying any plane would be fast if you put a big engine on it be kinda like saying any plane could be long range if you slap a laminar flow wing on it. Again im no expert but just an observation.

Lamellar flow was a development, just like jet engines were. You cannot transplant them back years before they existed to declare an earlier design to be primitive. Before the Mustangs laminar flow wings ever saw service the Spitfire had played its part in winning the Battle of Britain Malta and North Africa. The Mosquito did not have 5 digit NACA wing profiles but it did have advanced RAF profiles and a cooling system and other aerodynamics on par with a P-51....but it wasn't in service in 1939.

RAF airfoils?
RAF 34 AIRFOIL (raf34-il)

 

[michael rauls]

Lamellar flow was a development, just like jet engines were. You cannot transplant them back years before they existed to declare an earlier design to be primitive. Before the Mustangs laminar flow wings ever saw service the Spitfire had played its part in winning the Battle of Britain Malta and North Africa. The Mosquito did not have 5 digit NACA wing profiles but it did have advanced RAF profiles and a cooling system and other aerodynamics on par with a P-51....but it wasn't in service in 1939.

RAF airfoils?
RAF 34 AIRFOIL (raf34-il)

Yes i agree with everything in your post. I was ruminating on Ivans statement that" any plane would be fast if you put a larger engine in it" by answering isn't the engine and the airframe capable of housing it an integral part of the design and the resulting performance( of the spitfire in this case) be a result of all those design factors including but not limited to the engine. To further the point that all those factors are indeed a part of the design I pointed out that the statement that" any plane can be fast if you put a larger engine in it" ignores the fact( at least in my mind) that the engine IS a part of the design of the spitfire just as much as the lamellar flow wing was part of the mustang by pointing out that, in my opinion, saying "any aircraft could be fast if you put a larger engine in it" is perhaps the same as saying any plane could be long range if you slap a lamellar flow wing on it to give an example of why i thought this statement to be perhaps missing the larger picture, in my opinion.

 

[Shortround6]

The Spitfire falls on spectrum of speed vs power installed. Yes it is worse than Mustang, but then so is just about everything else and anything that falls between the Spitfire and the Mustang has some serious limitations of it's own.
The 109E had a parachute behind compared to the Spitfire. It's "low drag" is due to it being a much smaller airplane and when extensively modified into the 109F
(you might be hard pressed to take a 109E wreck and "restore" it into an F) it picked up around 20mph or more using the same engine (most got improved engines)
Obviously the Hurricane wasn't exactly low drag. The P-40 was actually pretty good. It's main failing wasn't streamlining (drag) but weight which affected climb (and other things).
Something that often gets left out is the effect of armament on fighter design. The guns and ammo of a 1930s fighter were it's payload and the weight and size of the armament package sometimes dictated the aircrafts layout (P-39 for example) but more often the size of the wing and other considerations.
In the mid 30s with a field length of a certain size if you doubled the number of guns and amount of ammunition then you might need another 6-12 sq feet of wing to provide the necessary lift, except that additional wing area might cost 3lbs a square or so in structural weight. landing gear and tires might need beefing up.
Once a plane is in production and especially after the shooting starts the customer (air force) often turned a blind eye to somethings going a few percentage points over the line but in prototype form things could get ugly if a pane didn't meet performance specifications.

 

[michael rauls]

Yes i agree with everything in your post. I was ruminating on Ivans statement that" any plane would be fast if you put a larger engine in it" by answering isn't the engine and the airframe capable of housing it an integral part of the design and the resulting performance( of the spitfire in this case) be a result of all those design factors including but not limited to the engine. To further the point that all those factors are indeed a part of the design I pointed out that the statement that" any plane can be fast if you put a larger engine in it" ignores the fact( at least in my mind) that the engine IS a part of the design of the spitfire just as much as the lamellar flow wing was part of the mustang by pointing out that, in my opinion, saying "any aircraft could be fast if you put a larger engine in it" is perhaps the same as saying any plane could be long range if you slap a lamellar flow wing on it to give an example of why i thought this statement to be perhaps missing the larger picture, in my opinion.

Ya sometimes it takes me a few tries to assemble my thoughts in an orderly manner and put them in writing.

 

[pbehn]

Once a plane is in production and especially after the shooting starts .

That is when everything changes, many aircraft remained in production purely because changing to something else means nothing for a long time then something a bit better later.

 

[Shortround6]

The Spitfire was also subject to a number of modifications, some rather ham handedly done. Much is made of the somewhat low performance of the MK V.
However not only did the MK V go from eight .303s to the two 20mm with the associated increase in weight and drag (protruding barrels and assorted lumps and bumps on the wing) but you had the infamous external BP wind screen on some aircraft and other small details that cost a few mph each. Build quality may have been something of a factor? at least for some of 1941?

I would note that the Mk V went from about 6450lbs for a MK VA with eight .303s to (and the fastest at 375mph) to 6525lbs for Vb (with drums?) to 6965 lbs for a Vc with a universal wing (and interior BP windscreen) and speed was down to about 360mph. Tropical filters and other things could bring down the speed considerably.

 

[Ivan1GFP]

Has the Mustang airframe with a Merlin Mk III and a fixed pitch two blade prop been evaluated to see if it could get airborne?

The Spitfire was a much lighter airframe which is where a lot of its performance came from. I am actually pretty sure it actually could get airborne but maybe not in a reasonable length runway. If you want to take that argument a little further, then how about a 100 HP engine that would easily get a Fokker biplane airborne but has no hope of powering a heavier aeroplane?

If you really want to compare airframes, then take a look at what has been run in the "Unlimited Class" air races. An Airacobra won in 1946, the P-40Q has raced though it crashed, Corsairs, Bearcats, Mustangs, Sea Furies race these days. Many of those planes don't have Laminar Flow wings either. When was the last time you saw a Spitfire race? Does it even have a chance of being competitive there? I don't believe we have ever seen a Hellcat or a regular P-40 race either.

As for actual fighter aircraft rather than racers, the problem with getting higher performance with a bigger and more powerful engine is that it will probably be heavier, have higher fuel consumption and range gets even shorter.

- Ivan.

 

[pbehn]

You raise a good point. Equally, AFAIK, the USAAF wasn't providing fighter defences for the UK mainland which, again, demonstrates that this was an integrated Allied effort.

The RAF was always responsible for UK defence. Things happened very quickly as far as daylight escort forces were concerned. The first P-51Bs to arrive were assigned to fighter groups and didn't have the rear tank. They also didn't have pilots. There was a chart of pilot US training which showed that the final stage of training was done in theatre, Chuck Jaeger certainly did. So at least in mid to late 1943 these squadrons were more like OTUs. The US forces were training for what they had to do, linking them in to the UK defence system and requiring them to keep the sky clear while they were training on type is a bit of an imposition. I have no idea if the LW did try sneak daylight attacks in 1943 they certainly had a few goes infiltrating the night bomber streams.

 

[Shortround6]

The Spitfire was a much lighter airframe which is where a lot of its performance came from. I am actually pretty sure it actually could get airborne but maybe not in a reasonable length runway. If you want to take that argument a little further, then how about a 100 HP engine that would easily get a Fokker biplane airborne but has no hope of powering a heavier aeroplane?

If you really want to compare airframes, then take a look at what has been run in the "Unlimited Class" air races. An Airacobra won in 1946, the P-40Q has raced though it crashed, Corsairs, Bearcats, Mustangs, Sea Furies race these days. Many of those planes don't have Laminar Flow wings either. When was the last time you saw a Spitfire race? Does it even have a chance of being competitive there? I don't believe we have ever seen a Hellcat or a regular P-40 race either.

As for actual fighter aircraft rather than racers, the problem with getting higher performance with a bigger and more powerful engine is that it will probably be heavier, have higher fuel consumption and range gets even shorter.

- Ivan.

Using air racers, especially the 1946-47 ones, as a benchmark doesn't actually tell us much. Many of the racers just used what they could buy cheap as surplus and sometimes it what they had flown in the war. They familiar with it. It took a few years to sort out what was competitive and what was not, and the hobby guys without much money tended to get left behind. Spitfires were more than a little hard to come by in US scrap and surplus sales. You could spend more shipping a surplus Spitfire from England than it cost to by an entire US fighter (with fuel still in the tanks) so yes, foreign aircraft were scarce.
By 1948 it took deep pockets and or sponsorship to get to the front of the pack although a few hobby flyers still showed up.
The Airacobra was as close to factory racer as you could get. Prep work was done in a Bell hanger by Bell employees in their off duty time with consulting done by Bell engineers. It may not have been paid for by Bell but no other race team in 1946-47 had that level of technical expertise.

The Problem with using the later racers as indicators of actual WW II performance is that many of the later ones were extensively modified. In fact even some of the last of the early racers were a far cry form stock condition.
despite this a Spitfire Mk XIV, stock except for gun and armor removal, finished 3rd in the 1949 Tinnerman Trophy race behind a F2G-1 Corsair and a P-51K

(Aaron King photo)
from 1949 National Air Races
One of the more extensively modified Mustangs was Bill Odum's

Radiators moved to pods on the wing tips.

Someplanes had some serious wing clipping going on.

(Aaron King photo)

On some planes the fuel mixture was not standard aviation fuel. Cook Clelands Corsairs sometimes used Triptane to allow around 4000hp.

another modified Mustang.

(Bill Meixner Collection)

Back then surplus warplanes were cheap and plentiful.
Nowadays Warbirds are rare, expensive and valued too highly to chop up into competitive racers.

The other thing about race results is that the manifold pressure and RPM are rarely mentioned so even if running standard AVgas, we don't know what the actual power levels were and some racers were satisfied just to compete and win some prize money to offset their costs and have a working engine/airplane to race another day rather than go for broke for first place.

 

[pbehn]

I seem to remember some P-51s being fitted with Griffon engines? Schurley Schome Mishtayke?

 

[davparlr]

Just saw these great pictures
by Terry in the "Flying Legends 2018" thead.

Please note the angle of the flaps.
They are doing just about nothing for lift and are acting as air brakes (drag producers and/or lift spoilers).
This was rather common for flaps designed in the mid 30s. You still needed a big wing for take-off but the flaps kept you from floating down the runway for a long distance on landing and steepened the glide angle/approach angle.

I had some personal experience to how effective flaps are as drag devices. C-141s had huge Fowler flaps with two settings Takeoff/Approach and Landing. Takeoff/Approach was mostly lift and Landing was mostly drag. We were deep into our 12 hour crew duty day and were very tired from flying what we called European shuttle, taking off from Torrejon AB, Madrid, we already gone to several places in Europe, typically Greece, Cyprus, Naples, and were now flying into Piza with a follow-on leg back to Torrejon. We were told by center to contact Piza tower for hand off. We tried several times to contact Piza to no avail. Due to this, we had to execute a low altitude penetration or procedure turn to ILS. Still no contact so we continued our approach and ran the check list, flaps approach, pause, gear down, before landing check list. Finally Pisa cleared us for landing, I called flaps landing (to be done when landing was assured) and started to land. Approach was normal and flare was normal. The plane would not settle on the runway. It floated, and floated, and floated. We were half way down the runway and I decided I'd better get the mains on the runway so I slightly lowered the nose and the plane settled on the runway. The C-141 also had massive anti-lock brakes and I knew it would haul it down and it did. On after landing check list, we discovered that the copilot had failed to put the flaps in landing and I had failed to check. It was a bit nerve wracking. What if that runway had been shorter. Fatigue, broken timelines, out of normal operations, are some of the things pilots have to be especially alert to.