Which is the better fighter, P-40F or Typhoon? (1 Viewer)

[Ivan1GFP]

Yes the enduring criticism of the p40 as being slow has always puzzled me. The Spitfire V witch seems like a fair mark to use as comparison to the best of my knowledge had a top speed of about 370. The Bf109 E slightly less, the F slightly more. The A6m 335 to 350 depending on subtype and whose numbers you believe.
All in the balpark of the p40 F/L or most models for that matter. Some a bit more, some a bit less but I have never heard criticism that the A6m or the Spitfire MkV for example were" slow".
There certainly are some lagit criticisms to be made of the p40 but I don't see how being slow is one of them.

Hello Michael Rauls,
I figure the Merlin P-40F/L was good for somewhere between 365 MPH and 375 MPH at critical altitude.
Down low, it lost quite a bit of speed as compared to Allison P-40s, but still was a relatively fast early war aircraft.
The A6M and Spitfire Mk.V have also been criticized as slow at various times.
At low altitude the Spitfire Mk.V in its "clipped and cropped" versions was a pretty decent hot rod but it didn't have that much altitude capability and didn't serve as an air superiority fighter that late into the war.
As for A6M, it is what you use if that is all you have.

Under 10,000 feet the Spitfire IX (Merlin 61, +15 lb-boost) appears to have roughly 20-30 mph on the Kittyhawk (v1720-39, 42-in boost).

With the Merlin 66 (+18-lb boost) it's around 30-40 mph.

Hello Greyman,
How do they compare to a P-40K with a V-1710-73 (F4R) and running 60 inches (+15 pounds boost)?
This was approved by Allison in December 1942 for the V-1710-39 (F3R) as well as the -73 engine and that was to address reports from the field that significantly exceeded these settings....
Try making a comparison at Sea Level. By the time you get to 10,000 feet, those early single speed supercharged engines were not going to keep up all that well with a two stage Merlin.

- Ivan.

 

[Glider]

so where is your evidence that the extra boost will make up the 30 to 40mph increase in speed.

 

[Greyman]

Are there tests for the Kittyhawk with those boost pressures? Using A&AEE tests of the Mustang I (F3R, 56-in boost) as a guide, it looks like the Kittyhawk would be in-between the Merlin 61 and Merlin 66 Spitfires under 8,000 feet (ie: roughly 10 mph faster than the former and 10 mph slower than the latter).

At 60 inches ... with eyeballing things it looks like it would be about equal to the Merlin 66 Spitfire under 6,000 feet. Probably a few mph faster than the Spit.

Though with +25-lb boost the Spitfire is ahead again by about 20 mph.

 

[Glider]

Rememering that the Typhoon was faster than all of them

 

[Schweik]

True but it handles like an overloaded bus...

 

[Schweik]

They mention running the p40f & L at 55 to 65 in remind me what that translates to in lbs of boost?

In Mediterranean Ait War volume 4 there are a lot of P40 L lost to engine trouble. I don't know if that has to do with overboosting or not sometimes it seems to be on days when they didn't even face any air combat

 

[Shortround6]

I don't mind the extra boost making up a good part of the speed where the extra boost existed.
What really bugs me is the assumption that the extra boost was available or useful at a range of altitudes.
It gets trotted out like like a magic talisman in just about every one of these discussions.

for Spitfire see:
http://www.spitfireperformance.com/bs543speed.jpg.
18lbs boost (not 15lbs ) which darn close to 66in available on a Merlin 70 engine from sea level to just under 16,000ft in all out level flight in low(medium) gear.
The much vaunted 70in of pressure in the Allison started disappearing at 2,000ft or less.

Cut the Merlins pressure for 18lbs down to 15lbs (60in) the SPit could hold 15lbs boost from sea level to over 18,000ft without ever shifting to high gear.

The older Merlin 61 engine could hold 15lbs of boost to 14,750ft in low gear in level flight.
A Spit IX with a Merlin 61 was tested at 363mph at 14,500ft at 15lbs boost while carrying a 500lb bomb.

No loss of hundreds of horsepower when climbing 4-5000ft above sea level. No loss of power when climbing??

The 57in or 60 in limits were realistic for the Allison they didn't disappear when the plane banked, or slowed while climbing.

 

[Shortround6]

They mention running the p40f & L at 55 to 65 in remind me what that translates to in lbs of boost?

In Mediterranean Ait War volume 4 there are a lot of P40 L lost to engine trouble. I don't know if that has to do with overboosting or not sometimes it seems to be on days when they didn't even face any air combat

What a surprise, not.

The "famous memo" does mention that very problem. see page 2, second paragraph.

Of course some of the engine trouble may have been due to ingesting dust/sand.

 

[Greyman]

Off topic yes but I had to do it. My brain is too right-sided for a bunch of numbers.

Kittyhawk IA

- A&AEE curve placed on data sheet FTH max speed at 42-inches (to the benefit of the P40)​

- thin line is my estimate (probably optimistic) of 60 inches based on A&AEE tests of Mustang I​

Spitfire IX

- A&AEE, Merlin 61, +15 pounds​

Spitfire IX

- A&AEE, Merlin 66, +18 pounds (thin line +25 pounds)​

 

[Schweik]

Off topic yes but I had to do it. My brain is too right-sided for a bunch of numbers.

Kittyhawk IA

- A&AEE curve placed on data sheet FTH max speed at 42-inches (to the benefit of the P40)​

- thin line is my estimate (probably optimistic) of 60 inches based on A&AEE tests of Mustang I​

Spitfire IX

- A&AEE, Merlin 61, +15 pounds​

Spitfire IX

- A&AEE, Merlin 66, +18 pounds (thin line +25 pounds)​

View attachment 524456

Why not add a Kittyhawk III / P 40K, a Kittyhawk II, a Spit V and a Typhoon to the chart.

Kittyhawk Ia is a much earlier vintage than Spit IX.

 

[Schweik]

What a surprise, not.

The "famous memo" does mention that very problem. see page 2, second paragraph.

Of course some of the engine trouble may have been due to ingesting dust/sand.

It does though the All8son memo is referring to later higher gear ratio engine variants, ala V-1710-81 /P-40M, and isnt appliccable to (Merlin engine) P-40 L anyway.

Though we know they overboosted those too...

 

[Glider]

True but it handles like an overloaded bus...

Clearly the US Test Pilots don't agree with you

The didn't like its longitudinal stability or the vibration from the engine but the Summary is very clear

Conclusion
The Typhoon has proved to be a very useful fighter bomber. Good high speed and maneuverability at low altitude coupled with sufficient firepower and exceptional load carrying ability make it an formidable weapon.

Other comments
Trim adjustments are slight for speed or power. (see observation on the P40N below)
The aircraft has an ideal gentle stall with proper warning
All control forces are reasonable up to 450 IAS where the ailerons become heavy

Manoeuvrability and Aerobatics
In General handling during manoeuvres and aerobatics is very good. Radius of turn is short and the aeroplane rolls well although aileron forces become heavy.

Its interesting to this last one to the same report done on the P40N
Aerobatics
Normal aerobatics may be performed, but require excessive strength on the controls due to high stick and rudder force

Another comment on the P40N
Gun Platform
Unsatisfactory due to change in rudder trim due to speed

So which of these is closer to handling like an overloaded bus?

 

[Shortround6]

It does though the All8son memo is referring to later higher gear ratio engine variants, ala V-1710-81 /P-40M, and isnt appliccable to (Merlin engine) P-40 L anyway.

Though we know they overboosted those too...

Metal fatigue is metal fatigue. The RR engine may react a bit differently but it will follow the same general pattern, while exceeding the design limits of the parts by 20-25% for a short period of time might not cause immediate failure it might shorten up the time to failure by 10-20 times (not percent).
On the Allison increasing the stress on the crankshaft by 25% above what it would tolerate forever for all practical purposes (10 million cycles) could cause failure in 200,000 cycles.

 

[Schweik]

I would also view the ability of the P-40 to dive to catch faster aircraft with a bit of suspicion. I am sure it was done, but perhaps not at the speeds given in this thread? or as easily as it is being presented?
we already have a debate about whether the P-40 could dive at 480 mph IAS or at 500+ mph IAS.
The manual that says 480 IAS was the red line also says that 5000-8000ft of altitude is needed to recover from a high speed dive.

So how much higher does the P-40 have to start out to be able to hit even 450mph in it's dive to catch the tip and run raiders?

Not every dive is vertical dive (or close to it) and considerable speed can be picked up in a less than 45 degree dive.

Perhaps a speed of only 420mph was needed to catch some of those planes, I don't know, but lets stop quoting max possible from a higher altitude than most P-40s aside from the F and Ls flew at.

We know they did catch faster-flying aircraft like Bf 109G-6 and Fw 190s - you can see the Luftwaffe loss records on that pretty clearly. The question is how they did it - some in head on passes and so on, but a lot of these were chases, as described by the pilots themselves. Pilot after pilot (German and American) noted that the P-40 could catch Axis fighters in a dive, and could evade in a dive.

The oldest manuals say 460 IAS, then they say 480 IAS, the later flight films (which you can find as videos) say 485, but this is for new pilots. Flight students. Combat pilots did push the limits a bit more. I have already posted the account of the Curtiss test pilot Herbert O. Fisher who personally flew check out flights on over 2,000 P-40s and also went out to various Operational Theaters to train pilots. He said that he did a split S and dove from 20 to 10,000 feet and pulled out at 500mph. The exact quote is:

"The standard procedure for an acceptance flight was a one-hour check of all major systems. Fisher had a specialty, he would take an aircraft up to "20,000, strain the engine upward, then go inverted, throttle full forward, and nose it over, losing 10,000 feet or more at 500mph+. He knew it was almost impossible to tear a P-40 apart in a dive, "

Now seeing as he checked out 2,498 P-40s in his role as a production test pilot, I'd say it's a safe bet it was generally normal practice to exceed 500 mph just as the various pilot accounts claim they did. The account above does also give us some idea how much altitude is needed to pick up that speed, with the caveat that it's different if you start lower. However I doubt they needed more than 3 or 4,000 ft to pick up ~450 mph.

Lets also keep in mind, once you are going say, 500 mph, even in a 45 degree dive, you are going to be at sea level very quickly indeed. 22,000 feet per minute downward if my math is right. So from 10,000 ft you can be down to sea level in ~ thirty seconds, maybe a minute or minute and a half depending how fast you accelerate into your dive. Either way it doesn't take long. Standard combat practice in P-40s (for evasion or pursuit) was to initiate a Split S into a vertical dive which helps initial acceleration, but you would want to pull out to a much more shallow dive in not too many seconds after that unless you were starting from very high up and being chased. Sometimes they also describe doing a chandelle before a dive instead, presumably because they were already going fast.

Now it is true that not every pilot may have been aware of the limits of the P-40 or how far they could push it. From reading pilot accounts I gather transition training was pretty marginal at best particularly in the RAF. The Soviets didn't even have manuals they could read so had to basically figure everything out on their own. Guys like Fisher did go out to the combat zones, he apparently flew several missions with US units in Burma for example, but it's unclear how fast all this disseminated. I think training was a major factor.

 

[Schweik]

Hello Schweik,
The Merlin P-40F/L may not have been as effective as the Allison P-40 on the Eastern Front.
It was slower at low altitudes by quite a lot because the Allison tolerated quite a bit more "overboosting" and would not have climbed quite as fast because it had less engine power and more weight.
The Merlin did give an advantage but it was above about 15,000 feet or so.

But I think they did overboost the Merlins as well. I believe the Soviets got a few P-40Fs by the way but I have been unable to trace how they used them. Probably sent to PVO units or the Baltic. I believe the Russians liked the Allisons better than the Merlins particularly for forward field areas though they burned them out very fast anyway partly due to problems keeping the oil clean, from what I've read.

My own opinion is that the P-40 was a second rate Air Superiority fighter by 1942 and treated accordingly:
In other words, in places where it continued to serve as a front line fighter, it was because the opposition was not considered of the highest caliber or where there simply wasn't anything comparable that was available. If there was anything else available, it got a secondary role.
Note that by the time the P-40M and P-40N came out, the P-40M was not even in use by US forces except as trainers. The ones that did enter combat did so as Lend-Lease aircraft.
This is getting a bit off topic from the discussion of Merlin P-40's though.

- Ivan.

Lol ... fair enough but I think you are overstating the limitations. Don't make me start another thread because I think P-40K compares pretty well to a Yak 1 or even a YAk-9D.

P-40M was intended as an "export only" variant though some did end up in the CBI and the Pacific somehow. It had a higher altitude rated Allison but at the expense of being a weaker engine and it was quite heavy.

The P-40L however was IIRC about 500 lbs lighter than an E or a K. But the Russians didn't need the higher altitude performance and would have preferred the P-40K, which you can see in the personal history of some of their Aces.

 

[Schweik]

Metal fatigue is metal fatigue. The RR engine may react a bit differently but it will follow the same general pattern, while exceeding the design limits of the parts by 20-25% for a short period of time might not cause immediate failure it might shorten up the time to failure by 10-20 times (not percent).
On the Allison increasing the stress on the crankshaft by 25% above what it would tolerate forever for all practical purposes (10 million cycles) could cause failure in 200,000 cycles.

But as you know they strengthened both the crank shaft and crank cased (going from peened to heat treated etc.) startin with the 1710-39 and culminating with the -73. The Allison memo was referring to the -81 which had a higher gear ratio so was more dangerous to overboost or over-rev.

We do know that almost all WW2 engines did gradually move to higher boost ratings through the war, certainly the Merlins did. The thing with the Allisons is that they were initially overly conservative in their recommended power ratings, and most of that was ditched almost from day one. They were not flying at 42" in combat for long (I mean, I'm sure people did but they died quickly or if lucky, got shot down and had the chance to explore more options)

 

[Schweik]

I don't mind the extra boost making up a good part of the speed where the extra boost existed.
What really bugs me is the assumption that the extra boost was available or useful at a range of altitudes.
It gets trotted out like like a magic talisman in just about every one of these discussions.

But you constantly lowball the numbers. P-40s weren't flying in combat at 42" Hq, certainly P-40F and Ls weren't. When the stats get rolled out they don't talk about the actual high boost settings of 57" or 60" they talk about 42" or 45" - because it's in the manual.

Notice in this chart that a 1944 RAAF test of a P-40N running at 57" boost (Allison engine) showed 3380 fpm up to 6800 ' at 57" boost, though it drops off rapidly after that. This means the critical altitude for that WEP rating was 6800'. That isn't high but it's hardly plowing altitude.

http://www.wwiiaircraftperformance.org/P-40/A29-412-climb-WEP.jpg

No loss of hundreds of horsepower when climbing 4-5000ft above sea level. No loss of power when climbing??

The 57in or 60 in limits were realistic for the Allison they didn't disappear when the plane banked, or slowed while climbing.

I agree 66" or 70" boost was limited to probably quite low altitude, but show me some evidence that they would lose power banking or climbing. As far as I know that is just your theory that you keep trotting out.

 

[Schweik]

Clearly the US Test Pilots don't agree with you

The didn't like its longitudinal stability or the vibration from the engine but the Summary is very clear

Conclusion
The Typhoon has proved to be a very useful fighter bomber. Good high speed and maneuverability at low altitude coupled with sufficient firepower and exceptional load carrying ability make it an formidable weapon.

Other comments
Trim adjustments are slight for speed or power. (see observation on the P40N below)
The aircraft has an ideal gentle stall with proper warning
All control forces are reasonable up to 450 IAS where the ailerons become heavy

Manoeuvrability and Aerobatics
In General handling during manoeuvres and aerobatics is very good. Radius of turn is short and the aeroplane rolls well although aileron forces become heavy.

Its interesting to this last one to the same report done on the P40N
Aerobatics
Normal aerobatics may be performed, but require excessive strength on the controls due to high stick and rudder force

Another comment on the P40N
Gun Platform
Unsatisfactory due to change in rudder trim due to speed

So which of these is closer to handling like an overloaded bus?

The Typhoon mate.

P-40 need for a strong right leg and / or the use of trim tabs at very high speeds were well known. Good pilots could easily manage it though.

I posted an account upthread of an actual wartime Typhoon pilot, a decorated combat veteran and one of the few survivors of his unit, in which he mentioned that the plane wasn't even flyable without the trim tabs. He barely managed to get home (flying at a 45 degree bank, (holding the rudder bar with his hands!) the whole way) and considered it a miracle he was able to land when his trim cable was damaged by an 88 mm AA gun.



Watch for yourself, he starts describing this at 13:00. His direct quote was "if the rudder trim goes on a Typhoon, you have no chance."

The Typhoon had basically the worst roll rate of any modern Allied fighter, and one of the worst turn rates for any single engined Allied fighter. It was fast but not very maneuverable.

 

[Schweik]

To be fair though, I think all this and more was fixed with the new wing on the Tempest. That is a sweet beast.

 

[pbehn]

decided to use the ignore function.