P40 Vs all other fighters in Europe

[FLYBOYJ]

I've got some time in a Victa Airtourer 100. When I did stalls for training, I was around 3,000 ft.
One day for giggles, my brother and I took it up to 10,000 ft. Due to its small wing area and 100 hp O-200, it has a rather poor climb rate. We got to 10,000 ft after a very long hour. ATC thought we were never going to make it.
Once we got their, we didn't know what to do - so with all the wisdom that a pair of teenagers could muster, we stalled it.
The stall was at the usual IAS, but bugger me it was different. Instead of the usual waffle and nose drop, it dropped a wing and despite almost instant full rudder to catch it - that wing kept going. It got past 90° very quickly. We eventually got right side up and wings level, but dropped a few thousand feet in the process.

Getting back to the question, any planes controls are less effective at altitude. The impact on the planes performance is likely related to the way wing loading and power loading decay with altitude.

This is more due to power loading decay IMO. I've flown C150s, 152s and 172s at altitudes in excess in 10,000' (I live at 6000' MSL) and generally felt no difference in stall/ spin recovery at higher altitudes than I would a bit lower. Now when I visit friends who reside close to sea level and have an opportunity to fly with them, I notice the performance difference, especially on take off.

 

[Schweik]

That was the P-400, it was P-39 fitted out to British specs and the O2 systems weren't compatible.

 

[Schweik]

I've got some time in a Victa Airtourer 100. When I did stalls for training, I was around 3,000 ft.
One day for giggles, my brother and I took it up to 10,000 ft. Due to its small wing area and 100 hp O-200, it has a rather poor climb rate. We got to 10,000 ft after a very long hour. ATC thought we were never going to make it.
Once we got their, we didn't know what to do - so with all the wisdom that a pair of teenagers could muster, we stalled it.
The stall was at the usual IAS, but bugger me it was different. Instead of the usual waffle and nose drop, it dropped a wing and despite almost instant full rudder to catch it - that wing kept going. It got past 90° very quickly. We eventually got right side up and wings level, but dropped a few thousand feet in the process.

Getting back to the question, any planes controls are less effective at altitude. The impact on the planes performance is likely related to the way wing loading and power loading decay with altitude.

Right, exactly. And planes with a higher wing loading and relatively poor power loading are going to have more problems like that at lower altitudes in hot weather, it seems to me.

 

[FLYBOYJ]

Right, exactly. And planes with a higher wing loading and relatively poor power loading are going to have more problems like that at lower altitudes in hot weather, it seems to me.

But power loading is going to be the critical factor. In the example shown that 100 hp O-200 was probably only producing 60 HP at altitude, thus the reason for the poor climb

 

[Schweik]

49th Pursuit Group absorbed many survivors of the Phillipines and Java, skimmed the cream of the newly arrived replacement pilots, and early on, served in an air defense role in the Darwin area, flying a single type, armed with a single weapon type, thereby simplifying maintenance.

I don't think that was the case. Quoting directly from this article:

The USAAF 49th Fighter Group over Darwin: a forgotten campaign | The Strategist

This year has seen many 75th anniversaries of battles and campaigns from the darkest hours of 1942, with the Battle of the Coral Sea (4 to 8 May) prominent. But in all these commemorative activities ...

www.aspistrategist.org.au

"By April, the 49th, under the command of Lieutenant Colonel Paul Wurtsmith, was in situ, with its three squadrons, the 9th, 8th and 7th, located at Livingstone, Strauss and Batchelor, respectively.

Wurtsmith was a career officer, specialising in 'pursuit' operations. He was a graduate of the USAAC Tactical School with 4,800 flying hours. His executive officer, Major Don Hutchinson, was another pursuit specialist with 2,500 flying hours. The 49th Fighter Group was fortunate to have such experienced leaders, plus a handful of veterans from the Philippines campaign, but that only masked the inexperience of the group, as out of its initial strength of 102 pilots, 95 had never flown the P-40 before."

8th and 35th Pursuit Groups were equipped with a variety of models of Airacobra, P-400s, P-39D ( of different blocks), P-39F. These were armed with three different weapons, vastly complicating supply and maintenance requirements. Plus, their theater of operations, defending Port Moresby, and conducting offensive operations across the Owen Stanleys, was a much more challenging one. P-38 squadrons being stood up or converting from other types got to cherry pick the best and brightest veteran pilots.

The 49th FG was also stationed at Port Moresby, and also had to fly over the Owen Stanleys, as was the Aussie 74th and 75th FS (also equipped with P-40s). One of the first P-38 squadrons in Theater was one of the 49th FG squadrons, 9th FS, but they did get to train on type.

However I hear what you are saying there about the various types of P-39s, especially the P-400s which had a lot of differences, ammunition, O2 system etc..

 

[Schweik]

But power loading is going to be the critical factor. In the example shown that 100 hp O-200 was probably only producing 60 HP at altitude, thus the reason for the poor climb

Power loading is also affected by the DA right? I'll take your word for it about wing loading being a factor (or not) as well. Seems like it would make a difference but I'm not a pilot.

 

[Greg Boeser]

Pressure altitude affects all aircraft the same, so it really isn't a factor. Unless there are clouds and mountains around. That's when things get "interesting".

 

[Schweik]

Well as you know, in NG and Solomons, there were both

 

[FLYBOYJ]

Power loading is also affected by the DA right? I'll take your word for it about wing loading being a factor (or not) as well. Seems like it would make a difference but I'm not a pilot.

It is - but if you have power to keep airflow over the wings (regardless of the wing loading) you're going to stay airborne.

 

[Schweik]

This is more due to power loading decay IMO. I've flown C150s, 152s and 172s at altitudes in excess in 10,000' (I live at 6000' MSL) and generally felt no difference in stall/ spin recovery at higher altitudes than I would a bit lower. Now when I visit friends who reside close to sea level and have an opportunity to fly with them, I notice the performance difference, especially on take off.

Could that possibly be because Cessna 150-172 etc. have very good stall characteristics and a low wing loading?

I get that it affects all aircraft equally, but (I guess I'm missing something here but I don't see it yet) it seems like an aircraft which was already kind of on the edge of being hard to control and / or 'twitchy' would have more trouble in the degraded (thin / hot air) conditions than one with a very good wing loading that was easy to handle.

 

[Schweik]

Don't aircraft with larger wings handle better at high altitude? Isn't that why they had the HF and LF Spitfire, the former having the extended wing tips?

 

[FLYBOYJ]

Pressure altitude affects all aircraft the same, so it really isn't a factor. Unless there are clouds and mountains around. That's when things get "interesting".

Pressure altitude is the height above a standard datum plane based on a barometric pressure. That's what you would adjust your altimeter to based on airfield pressure. With that known you can calculate your DA

 

[FLYBOYJ]

Don't aircraft with larger wings handle better at high altitude? Isn't that why they had the HF and LF Spitfire, the former having the extended wing tips?

View attachment 654739

Yes - because now you have a larger wing area to support the aircraft. Your lift coefficient will be higher. That's why gliders (and other aircraft) have long wings.

 

[FLYBOYJ]

Could that possibly be because Cessna 150-172 etc. have very good stall characteristics and a low wing loading?

Compared to a Victa Airtourer 100 possibly. The 150/ 152 has little dihedral so the stall is more abrupt and a wing tends to drop, but you want that in a trainer. The 172 stalls a bit cleaner

I get that it affects all aircraft equally, but (I guess I'm missing something here but I don't see it yet) it seems like an aircraft which was already kind of on the edge of being hard to control and / or 'twitchy' would have more trouble in the degraded (thin / hot air) conditions than one with a very good wing loading that was easy to handle.

To a point, again, how much air is being pushed over the wing? That's where the power factor comes into play.

 

[FLYBOYJ]

Don't aircraft with larger wings handle better at high altitude? Isn't that why they had the HF and LF Spitfire, the former having the extended wing tips?

View attachment 654739

Here's more on this;

Lift-to-drag ratio - Wikipedia

en.wikipedia.org

 

[Schweik]

Compared to a Victa Airtourer 100 possibly. The 150/ 152 has little dihedral so the stall is more abrupt and a wing tends to drop, but you want that in a trainer. The 172 stalls a bit cleaner

Cessna 172 is the only one I ever flew, it seemed very gentle. Parasol wing, low wing loading etc. In spite of quite low power.

To a point, again, how much air is being pushed over the wing? That's where the power factor comes into play.

What I meant is, a Cessna (of any kind) has very benign stall characteristics and very low wing loading compared to a P-39 for sure right?

If the HF Spitfire had it's wing extended by 4 feet to improve handling in thin air, and the P-39 has a wingspan 5 feet shorter than an A6M2, 4 feet shorter than an F4F-3, and 3 feet shorter than a P-40, it stands to reason that at some altitude, the wing will play a role in higher altitude / more severe DA conditions. Ratios are similar vis a vis wing area and wing loading.

The question would then be at what altitude would that start to become noticeable or telling?

Otherwise if it's just a matter of power to weight ratio, P-39 looks pretty good.

 

[FLYBOYJ]

What I meant is, a Cessna (of any kind) has very benign stall characteristics and very low wing loading compared to a P-39 for sure right?

Yes - it is basically a trainer and designed that way

If the HF Spitfire had it's wing extended by 4 feet to improve handling in thin air, and the P-39 has a wingspan 5 feet shorter than an A6M2, 4 feet shorter than an F4F-3, and 3 feet shorter than a P-40, it stands to reason that at some altitude, the wing will play a role in higher altitude / more severe DA conditions. Ratios are similar vis a vis wing area and wing loading.

It will and again *Depending how much air is flowing over it*

The question would then be at what altitude would that start to become noticeable or telling?

That's is dependent on the aircraft service ceiling

Otherwise if it's just a matter of power to weight ratio, P-39 looks pretty good.

But it starts running out of power at around 15,000'

 

[Shortround6]

Find the tests/reports for the Spitfires, unfortunately only they one compared two sets of tips at the same time.
There was a difference in the wing tips. However sometimes it was subtle, at least at most altitudes. Like the clipped wingtip not showing much difference until around 20,000ft was reached? Although it improved roll. it is interesting because you should swap the set of tips back and forth if you wanted to. I beleive the Clip version gave you 231/2 sq ft, normal version gave 242 sq ft and the extended tip gave 248.5 so something else beside just wing area was going on. You were altering the aspect ratio of the wing and that can affect actual lift ratio of the whole wing.
Once you start comparing one wing and fuselage to another you had better know what you are doing.

 

[FLYBOYJ]

There was a difference in the wing tips. However sometimes it was subtle, at least at most altitudes. Like the clipped wingtip not showing much difference until around 20,000ft was reached? Although it improved roll. it is interesting because you should swap the set of tips back and forth if you wanted to. I beleive the Clip version gave you 231/2 sq ft, normal version gave 242 sq ft and the extended tip gave 248.5 so something else beside just wing area was going on. You were altering the aspect ratio of the wing and that can affect actual lift ratio of the whole wing.
Once you start comparing one wing and fuselage to another you had better know what you are doing.

When I crewed at Reno, we had custom wingtips with a slight upward slope designed by some Scale Composites folks. They gave us better roll rates but we lost a few MPH. After flying one race and almost getting passed by another aircraft, we put the stock wingtips back.

 

[Schweik]

Find the tests/reports for the Spitfires, unfortunately only they one compared two sets of tips at the same time.
There was a difference in the wing tips. However sometimes it was subtle, at least at most altitudes. Like the clipped wingtip not showing much difference until around 20,000ft was reached? Although it improved roll. it is interesting because you should swap the set of tips back and forth if you wanted to. I beleive the Clip version gave you 231/2 sq ft, normal version gave 242 sq ft and the extended tip gave 248.5 so something else beside just wing area was going on. You were altering the aspect ratio of the wing and that can affect actual lift ratio of the whole wing.
Once you start comparing one wing and fuselage to another you had better know what you are doing.

Two comments on that - one thing I remember reading in pilot interviews about the HF wingtips, is that they disliked the pointed wingtips due to a very negative impact on roll rates. Which again makes me think of the Soviet complaints about the Hurricanes operating near Lenningrad.

I could be remembering this wrong but IIRC LF Spitfires were not doing so well by 20,000 ft due to the engines (Merlin 45M or 50M) critical altitude.

For example this chart for a Spit VB with a Merlin 50M tops out at 350 mph and +15lb boost at just below 6,000 ft. By 20'000 ft it's down to 337 mph and +5 lb boost.

Compare this to a Spit V with a Merlin 45 making 372 mph at 20,000 ft with +9 lb boost.