P40 Vs all other fighters in Europe

[Shortround6]

You know but some of our readers do not.

Like saying the the 2 pitch prop would give about the same speed as the CS prop. It would but a Spitfire I CS could cut around 3 minutes or more in the time to 20,000ft.
Going from 11. 3 minutes to 7.7 minutes for that climb is a major change.
Like wise the change in work load for the pilot while in combat may be significant.

 

[Greyman]

Like wise the change in work load for the pilot while in combat may be significant.

I've always said that a lot is made of the Spitfire I vs. 109E re: fuel injection and engine cutting (easy to explain to the casual reader/viewer in a couple of sentences) -- but I'd much rather have a constant speed prop and no fuel injection (Spitfire I) than the opposite (109E).

As the Luftwaffe report on the Hurricane and Spitfire said; 'Both types are very simple to fly compared to our aircraft, and childishly easy to take-off and land.' This really matters in a war where you don't have time to train a large cadre of expert pilots.

 

[nuuumannn]

As mentioned earlier, the earliest Emils had the VP switch on the instrument panel, which meant that changing prop pitch was a juggling act that required moving hands about the cockpit, either taking one's hand off the power lever or off the joystick; either way the pilot has to think and act fast in the heat of combat. Sensibly, in later Emils, not sure what production batches or so forth, it was put next to the power lever.

 

[pbehn]

Not to mention more efficient acceleration, better fuel consumption, better power usage across the range of the flight regime, the advantages certainly outweighed maximum speed. Nonetheless, it was recognised before the war that VP props were more efficient on the fighters, but production and supply was not what it would eventually become. The British industry was working at peacetime levels when the First Spitfires and Hurricanes entered service.

Spitfires with wooden fixed pitch props were a little faster than the constant speed equipped units. The benefits of the conversion of course enormously outweigh the slight reduction in top speed.

Fitting of CS props was an issue, which one do you fit? Obviously for the British it had to be made in UK, that is why ROTOL was formed. Then there is the question of what is it designed for? Between the declaration of war and the Battle of Britain the Merlin increased its power output by a huge amount. Any CS prop optimised for a Hurricane with 85 Octane fuel would need to be replaced by one optimised for 100 Octane. The LW noticed the improvement of the Spitfire MK II when introduced but at the end of the BoB the high altitude Jabo raids found that the Spitfire MkI was the best to counter them.

 

[Shortround6]

I have read (could be wrong) that one thing flight leaders tried to do in the first few flights over the French bases with new pilots to see how they were handling the prop pitch switch.
This was before trying to fly over England.
It the switch was not adjusted properly sometimes the new pilots could not maintain formation. And sometimes even they could maintain formation they were using a wrong throttle and pitch combination that used up fuel faster than it should have.

Granted a British pilot could set the CS control wrong also (and we know that P-38 pilots weren't using the right combinations at times

 

[nuuumannn]

Fitting of CS props was an issue, which one do you fit? Obviously for the British it had to be made in UK, that is why ROTOL was formed.

True, but De Havilland props were based on Hamilton Standard props. Availability is also an issue, rapidity of production to meet needs. British military expansion in the late 1930s was rapid for an industry used to peacetime and not every company was able to keep up with Air Ministry production orders, which meant delays.

 

[Shortround6]

Fitting of CS props was an issue, which one do you fit? Obviously for the British it had to be made in UK, that is why ROTOL was formed. Then there is the question of what is it designed for? Between the declaration of war and the Battle of Britain the Merlin increased its power output by a huge amount. Any CS prop optimised for a Hurricane with 85 Octane fuel would need to be replaced by one optimised for 100 Octane. The LW noticed the improvement of the Spitfire MK II when introduced but at the end of the BoB the high altitude Jabo raids found that the Spitfire MkI was the best to counter them.

I am not sure it works that way? Maybe one of our experts can get in on this.

A CS prop is set up to run at a certain pitch at a certain air speed/altitude. The Rotol props (at least the early ones) would handle 35 degrees of pitch change?
Actually the prop should be set to run a certain speed at a certain pitch and hopefully it should be correct at hi speed once the prop has changed pitch?
Now at 17,000ft or so there shouldn't have any change in the pitch settings as the Merlin and XII should have been making the same power at the same rpm at that altitude.
Unless they adjusted them for the difference in speed due to antennas and other items that produced drag.

I could be way wrong but think the idea of the CP propeller was to let the the prop advance the pitch as long as the engine was making the set rpm.
If the engine was making more power (higher boost) then the prop would advance the pitch change until the prop couldn't advance the pitch anymore.
Your top speed is the same but with the higher boost you are going to get their quicker.

Now if you are doing a higher speed at lower altitude than you used to do because of the higher boost were does that fall on the propellers pitch range?
does 335mph at 10,000ft call for more pitch change than 320mph at 10,000, I would say yes, but if your prop hasn't maxed out it's pitch range because the prop does have to give you a enough pitch to allow for 350mph (+) at 18,000ft is it going to make any difference? Allow for a little bit if over pitch to the plane can dive as the pilot is throttling back.

Now if you are putting a prop on a Hurricane instead of a Spitfire you may want different blades and/or you may want to adjust the prop pitch back a little bit because the Hurricane is never going to use the max pitch of the Spitfire.
Unless the Hurricane has enough to extra travel so it doesn't really matter.

I could be way off.

 

[FLYBOYJ]

Actually think of a CP propeller like the automatic transmission in a car except you have the ability to control at what RPM the transmission shifts into the next higher gear. At take off you're looking at a low pitch, high RPM and you want to watch manifold pressure, (especially if you're running a supercharger so you don't overboost). As you're climbing and picking up speed you'll pick a prop setting that will give you a good rate of climb at a given manifold pressure and RPM. I remember flying a T-34 and set up for 2500 RPM at 25" ("25 square") manifold pressure as I was climbing and starting to pick up speed. At cruise I remember looking at either "24 square" or 2300 rpm at 24" manifold pressure. 2600 rpm at 26" manifold pressure (max numbers) would eventfully get me to max indicated airspeed, which was something like 160 or 170 mph. If I was flying at a certain cruise and wanted to do maneuvers, I wouldn't touch the prop control as my prop governor was now keeping my numbers in place.

It's been at least 18 years since I've flown an aircraft on a regular basis with a CP prop. Maybe some of our other resident pilots can chime in, let me know if I'm out to lunch or verify my memory.

Wes?

 

[FLYBOYJ]

Here's a great reference, start at page 12-5

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/airplane_handbook/media/13_afh_ch12.pdf

 

[FLYBOYJ]

 

[Peter Gunn]

I just want to know who designed this:

View attachment 655572

... thinking it was a good idea. It looks like a hotel having 'roid rage.

HEY!!!

DO NOT HARSH ON MY PRECIOUS FRENCH PRE-DREADS!!!

THEM'S FIGHTEN' WORDS SONNY...





Remember, you're talking to a guy that thinks the Brewster Buffalo is stylish, yeah I know, but not even therapy has helped with that.

 

[SaparotRob]

HEY!!!

DO NOT HARSH ON MY PRECIOUS FRENCH PRE-DREADS!!!

THEM'S FIGHTEN' WORDS SONNY...





Remember, you're talking to a guy that thinks the Brewster Buffalo is stylish, yeah I know, but not even therapy has helped with that.

You tell 'em Bro'!

 

[MikeMeech]

I am not sure it works that way? Maybe one of our experts can get in on this.

A CS prop is set up to run at a certain pitch at a certain air speed/altitude. The Rotol props (at least the early ones) would handle 35 degrees of pitch change?
Actually the prop should be set to run a certain speed at a certain pitch and hopefully it should be correct at hi speed once the prop has changed pitch?
Now at 17,000ft or so there shouldn't have any change in the pitch settings as the Merlin and XII should have been making the same power at the same rpm at that altitude.
Unless they adjusted them for the difference in speed due to antennas and other items that produced drag.

I could be way wrong but think the idea of the CP propeller was to let the the prop advance the pitch as long as the engine was making the set rpm.
If the engine was making more power (higher boost) then the prop would advance the pitch change until the prop couldn't advance the pitch anymore.
Your top speed is the same but with the higher boost you are going to get their quicker.

Now if you are doing a higher speed at lower altitude than you used to do because of the higher boost were does that fall on the propellers pitch range?
does 335mph at 10,000ft call for more pitch change than 320mph at 10,000, I would say yes, but if your prop hasn't maxed out it's pitch range because the prop does have to give you a enough pitch to allow for 350mph (+) at 18,000ft is it going to make any difference? Allow for a little bit if over pitch to the plane can dive as the pilot is throttling back.

Now if you are putting a prop on a Hurricane instead of a Spitfire you may want different blades and/or you may want to adjust the prop pitch back a little bit because the Hurricane is never going to use the max pitch of the Spitfire.
Unless the Hurricane has enough to extra travel so it doesn't really matter.

I could be way off.

Hi
Information from the late 1930s before WW2 is available from the part work 'Aero Engineering', Volume I, in an article on 'The Variable Pitch Airscrew' by Flt-Lt. J W Bell, Service Manager, Airscrew Division, de Havilland Aircraft Co.:

In 1938 the de Havilland CS prop was flying on the Bristol Perseus powered de Havilland Flamingo. In November 1938 the Rotol (ROlls-Royce/BrisTOL) CS propeller (Hele-Shaw-Beacham patents) was being used for the RAF's Long Range Development Unit Vickers Wellesleys, powered by Bristol Pegasus XXII engines (using 100 octane fuel), these props replaced the de Havilland (Hamilton) two-pitch type normally fitted. I believe the RAF initially prioritised bombers for CS (and two-pitch) props, the production lines of both Hurricanes and Spitfires were fitting CS props by the end of 1939, the alteration of de Havilland two-pitch to CS on the squadrons in mid 1940 was to convert the fighters that had been already delivered prior to the change (the change was possible and mentioned in the above attachment).

Mike

 

[Mike Williams]

I have read (could be wrong) that one thing flight leaders tried to do in the first few flights over the French bases with new pilots to see how they were handling the prop pitch switch.
This was before trying to fly over England.
It the switch was not adjusted properly sometimes the new pilots could not maintain formation. And sometimes even they could maintain formation they were using a wrong throttle and pitch combination that used up fuel faster than it should have.

Granted a British pilot could set the CS control wrong also (and we know that P-38 pilots weren't using the right combinations at times

Oberleutnant Ulrich Steinhilper of III/JG 52 wrote of the difficulties new pilots found operating the Me 109 E's propeller:

We began our climb almost immediately after take-off and he was constantly using the radio to ask us to slow down so that he could keep up. It was obvious that he wasn't manipulating the pitch control with the skill of the more seasoned pilots to produce the same power as our machines. We tried to tell him what to do on the radio but to no avail. Eventually, about half way across the Channel at 4,000 metres Kühle told him to leave the formation and return to base. Ulrich Steinhilper & Peter Osbourne, Spitfire on my Tail, (Independent Books, Bromley, 1990), p.303.

 

[Mike Williams]

CS prop took care of that for the pilot. Somewhat.
Like in the turn the constant speed governor would automatically to reduce the pitch of the propeller to keep the prop pitch at a good match to aircraft speed as the engine was making full power.

This is something often ignored with the 2 speed prop.
In order to get "best" performance the airplane with a two speed (basically one speed/fixed pitch after take-off)
the pilot had to reduce the engine throttle to keep from over speeding the prop. The prop is not operating at anywhere near a good angle if the airspeed in not near full speed and unless the engine is throttle reduced and the engine rpm reduced. Trying to fly a tight turn with the engine running around 20-30% below max power is obviously going to affect the planes turning ability.

Spitfire I Aeroplane, AP 1565A

 

[Wild_Bill_Kelso]

Greg's Airplanes and Automobiles on Youtube has a recent video on the P40.
I don't know how to make the movie work here but a link is below.



General things I've read here involve how it's use started before Dec 1941 when the USA was not putting a lot of money into research. The British used it in North Africa in 1941 and they were trying to use it with dogfighting tactics that it was not totally successful at. Then it was Lend Leased to Russia and their airforce had been hit hard by Germany so pilot skill and tactics could have suffered there also.

Greg's video linked above impressed me with how all the added boost and power only increased top speed 20-25mph. That was in part because it still ran out of power before it was able to benefit from reduced drag up high due to the single stage supercharger situation.

I generally like that guy's videos but he went off the rails in this one IMO. The Merlin-engined P-40 was considered by the USAAF to be the only one which could contend with Bf 109 or MC 202 / 205. The top speed doesn't tell the story, the real issue was altitude. As others mentioned, Allison P-40s began to really lose steam somewhere between 12,000 - 16,000 ft (depending on the specific type). The ones that still had power at 16,000 ft sacrificed a lot of the beast like power that say, a P-40K had 5,000 ft lower.

The P-40F/L (merlin engine) had decent power at 20,000 ft and was in the game at 23-24,000. They could make 370 mph at 20,000 ft. That meant they could tangle with 109s an C.202 when used as top cover. This meant for example they could still turn into attacks guns blazing, which was the standard tactic when facing high flying 109s. And thanks to the two speeds, they still performed pretty well down low. All of the USAAF fighter squadrons in North Africa used P-40F/L, with the brief exception of some P-40Ks by one squadron of the 57th FG, just due to shortages. The British only equipped 2 squadrons with the F/L ("Kittyhawk II and IIA") and found when they tried to switch back to the Allison types, casualties increased dramatically.

The merlin engined P-40 was definitely needed in the North African campaign and in fact it was probably the single most important fighter type from early 1942 through the end in Tunisia in June 1943. One of the major Axis bases, at Pantelleria just off shore of Tunisia, was actually 'captured' by the 325th FG. After that, into the Sicily campaign some of the better mark Spitfires and improved P-38s were arriving in some numbers. But the merlin P-40s were still being used as fighters through the Battle of Anzio (June 44).

In the Pacific, they did also use some of the Merlin P-40s, but the Allison types were good enough and able to hold their own pretty well. In China for whatever reason, they seemed to dominate.

The P-40 was a deeply flawed aircraft with some excellent features. It was a well designed airframe and fairly aerodynamic (though nothing like the low-drag P-51). The Allison P-51 by the way did not do so well in air combat and did not compare at all to the P-40 on a mission for mission basis in China or in Italy, except (in the A-36 version) as a bomber. The P-40 was deemed too flawed to continue to use but extended teething issues with and / or relatively slow production / development of other US types meant that it remained in use far longer than planned, and it turned out to have features which made the aircraft able to survive combat and destroy enemy aircraft much better than it should have done. Which is why it remained in use, not just because there were no other options (there were).

The flaws were the altitude limitations and rate of climb, especially when fully loaded.

The advantages were:
Very good turn rate (on the Allied side, second only to the Hurricane and Spitfire, and various biplanes)
Excellent roll rate (second only to the P-51 and Fw 190, IIRC)
Good dive acceleration and high dive speed (fast enough in a dive to evade Zeros and Ki-43s, just barely enough to often if not always evade Bf 109s)
Trim tabs so it could still be controlled, albeit with some difficulty, at very high speed (making it easier to evade A6M and Bf 109 in dives in particular)
Moderately good range (better than Bf 109, MC 202, Spitfire and Hurricane, but not comparable to A6M, P-51, P-38 or F4U) meaning it could climb to altitude before combat and reach farther for strikes
Heavily armed
Strongly built (to withstand 10G) and pretty well armored
Relatively reliable and easy to maintain (still temperamental as all warplanes were, but far less so than many other competing types, meaning it was available and in larger numbers than many other fighters in a given Theater.
Pretty effective at bombing and carrying a substantial bomb load - more than a lot of light and medium bombers.

All of that meant that pilots often survived engagements, and when they had a chance to attack enemy aircraft, they often destroyed them. This is why most pilots that flew them really liked them, whereas commanders and administrative people did not. It was not a plane of the early war but of the middle, and it played a very important role for US in Pacific, China / Burma / India, and North Africa, and a very important role for the British in North Africa, and for the Russians, all especially during late 1941 through early 1944. Really, the turning point of the war.

 

[GrauGeist]

The RAF (and RAAF) used the Tomahawk in North Africa before receiving Kittyhawks.

 

[Wild_Bill_Kelso]

I don't recall hearing that either and in a bit of irony, it was the .30 MG that jammed on Lt. Rasmussen's P-36, leaving him with only a .50 MG to engage the Japanese that morning at Pearl Harbor.

They did have significant problems with the wing-mounted .50 cal guns in the early P-40D and E (Kittyhawk I and IA), usually after pulling G. They made some changes which seemed to alleviate this substantially by around mid 1942, but it was largely understood that there was still a risk of the guns eventually seizing up if they were fired while pulling G, which was sometimes done anyway. Some pilots described each gun 'packing up' one by one until they were all jammed.

The nose guns could jam too but far less often. The Tomahawk (P-40B/C) types had charging handles in the cockpit which allowed jammed guns to be recharged. The Kittyhawks were supposed to be equipped with electronic gun chargers that could be used to reset the guns if they jammed but these did not seem to work in practice.

Apparently by the time the P-40K came out the problems were substantially resolved.

My understanding is that all fighter aircraft with wing mounted guns had this problem to one extent or another. I know in the Middle East and in Australia they had the same issue with the 20mm Hispano. In Australia the problem with Spitfire Mk Vs was particularly severe and was also related to serious problems with their ammunition and with gun heaters.

 

[Wild_Bill_Kelso]

The RAF (and RAAF) used the Tomahawk in North Africa before receiving Kittyhawks.

yes, and the SAAF as well, who got stuck with them the longest (into 1943 for at least one unit). In some ways the Tomahawks were better than the early Kittyhawks, as they were lighter so had a much better climb rate etc., but not after they started rating the engines for higher boost and RPM on the Kittyhawks.

 

[Wild_Bill_Kelso]

I should clarify my earlier long post. P-40s were there from fall 1941. The first merlin engined P-40 started showing up in Mid 42 in small numbers in US units (squadrons from the 33rd then 57th FG) that were initially attached to existing British units that had been in the Theater for a while. Gradually the numbers were ramped up.