Bf-109 vs P-40

[GrauGeist]

It is interesting that WW2 planes engines did not have oil or air filters.

Not sure what you mean by this, but they most certainly did.
For example, the DB601 had it's oil filter located at the rear of the engine, right below the throttle gearbox and fuel pumps.
The Allison V-1710 had it's oil filter on the right-rear of the engine, located below the fuel injector feed tube, sometimes referred to as an "oil strainer".
Most radials have their filter or "sock" located at the sump pickup - the BMW801's oil filter was located at the rear of the engine, by the oil heater, and had an advanced oil sludge filter, too (schlammablass).

 

[pbehn]

Yes go read

I have, engines did have oil filters (see post above) and most in desert environments had air filters, the Spitfire 's was called a Vokes filter. The rest of your post is actually just a comparison of engine stroke, which when multiplied by RPM gives piston speed, see post by S/R.

 

[tomo pauk]

It is interesting that WW2 planes engines did not have oil or air filters.
So contaminates also were a cause for early wearing out of the engines.
Peace time operations also ran engines at lower HP levels!
Combat pushed the engines to their limits as it was a life death situation.
Maximum performance and how to get it became a game.
Germans standardized on 96 octane fuel and used ADI or NOS to improve performance.
Allies had 100, 130, and 150 octane, Radial engines adding ADI for more performance.
German engines were 37 liters to our 28 liters and rarely ran them above 2800 rpm.
The Allison was pushed to 3600 rpm, mostly limited to 3200 and the Merlin 3000.
Some of the later British Sleave Valve engines went to 4000 rpm
To get more power the Germans would bore out their engines and port and polish the runners.

Always wondered what a Reno Racer air speed would be at best altitude?

Where is proven beyond doubt that:
- WW2 planes engines did not have oil or air filters
- Germans standardized on 96 octane fuel
- German engines were 37 liters to our 28 liters
(and 'our' - who are 'we'?)
- The Allison was pushed to 3600 rpm, mostly limited to 3200
- Some of the later British Sleave (!) Valve engines went to 4000 rpm
- To get more power the Germans would bore out their engines and port and polish the runners.

Yes go read

Sending fellow members to a wild goose chase instead of providing exact answer(s)? Not a way to earn respect among the members.

 

[pbehn]

Easy to overlook what is happening in an engine.
An engine turning at 3,000RPM is doing 50 Revs per second, that is the piston goes from TDC to BDC and back to TDC, so it starts and stops 100 times per second. On a six inch stroke motor the piston covers 50 ft per second but stops 100 times per second.
Increasing the revs to 3,600 the piston covers 60 ft per second but stops 120 times per second. The mean piston speed increases in a linear fashion with revs but the maximum speed increases exponentially as do the engine loads.
Merlin_______ Bore 5.4" stroke 6"
Griffon______ Bore 6 " stroke 6.6"
Alison V 1710 _Bore 5.5" stroke 6"
DB 605______Bore 6.06 stroke 6.3"
Sabre _______Bore 5" stroke 4.75"

To produce power the combustion/explosion must exert pressure on the piston, as revs increase on long stroke motors the piston accelerates as fast as the flame front which is why and how you can increase revs and decrease power in addition to blowing everything to pieces.

 

[Shortround6]

Allisons were rated at 3600rpm. However this was the allowable over speed in a dive with the throttle part closed, this was usually for some brief period of time like 20 or 30 seconds? Throttle was not fully closed to keep the prop from trying to turn the engine. Somewhat of a balance was needed. The engine was in no way, shape or form making anywhere near rated power while doing this.
later Allisons got the allowable over speed raised to 4000rpm?
There is some discrepancy between what Allison said the later 12 counterweight cranks could do and what the USAAF put in the manuals. I believe ALlison said the 3200rpm limit but the USAAF held to the 3000rpm limit on many (but not all?) of the engines. This was the end of 1943/beginning of 1944 so it doesn't really affect too many planes except late P-38s.

This is a problem with fastening on one little tidbit of information and trying to make a big deal of it. Without context (time of use or scale of use) it doesn't really tell us what was going on or just confuses things.
In 1941-42 some units in the field were overspeeding Allison engines but this was not approved by either Allison or the USAAF/RAF high command (unless someone has docurmantion to the contrary).

I believe the Merlin was also allowed a fair degree of overspeed in a dive.

 

[Schweik]

This is a problem with fastening on one little tidbit of information and trying to make a big deal of it. Without context (time of use or scale of use) it doesn't really tell us what was going on or just confuses things.
In 1941-42 some units in the field were overspeeding Allison engines but this was not approved by either Allison or the USAAF/RAF high command (unless someone has docurmantion to the contrary).

I believe the Merlin was also allowed a fair degree of overspeed in a dive.

The Russians are the only ones I know of who specifically mentioned flying at higher RPMs - when I read that I assumed they really meant overboosting (higher manifold pressure). Now I understand the context a bit better.

What would the advantage of over-revving be over overboosting, or do the two go together?

The latter (overboosting) seems to have been a semi-institutionalized practice though. The Allison memo linked upthread noted that Allison itself had already approved 60" Hg manifold pressure as a WEP setting before Dec 1942, and referred to 'near 70"' as a common practice among "The Australians" and 66" as a common setting among unnamed American squadrons operating in North Africa. They specifically mentioned throttles being "rewired" for that power setting.

This matches anecdotal evidence of many pilots commenting on overboosting P-40s as a combat adaptation.

So given the substantial power increase and corresponding improvements in speed, acceleration, and climb (and probably dive acceleration as well and perhaps turn radius too) I think we can assume that it was a militarily significant practice on the strength of that document alone, especially in light of all the anecdotal comments.

I have also read anecdotal reports (in MAW for example) of P-40 squadrons having a particular aircraft which was known to be faster than the others. One of them was involved in a friendly fire incident when it shot down a Spit Vc from 1,000 yards after a long chase.

This may represent a modified engine or throttle, or it may just be a better build quality or something.

S

 

[Schweik]

Maybe it wasn't universal but you need a better system than looking for scorch marks and more oil than usual on the outside of the plane. These planes used gallons of oil per flight. A P-47 could use a couple dozen gallons in one flight.

Of course. Any good crewchief would be looking the plane over and have many other ways to tell. I just remember reading references to this specifically from the Russians and USAAF squadrons in the Med; i.e. they said that looking at the plane when it landed they could tell if it had been 'pushed' from the extra oil stains and scorch marks behind the exhaust stacks.

S

 

[Shortround6]

Trouble with this is if the engine was "pushed" in the morning and then flew in the afternoon did they really have time to clean the morning oil stains of and repaint the area behind the exhaust stacks before an afternoon flight?

Sometimes due to weather no flying was done for days at a time and at other times several missions were flown in one day.

 

[Schweik]

Some comments on rpms / Allison engines by Golodnikov

Part 2

"N. G. The Tomahawks had the Allison engine, not very good, but in itself powerful. As one pushed it to full RPMs, toward maximum output, it would begin to �make metal� [tiny metal particles in the oil]. But apparently it was our fault because, we were told, we had insufficient �oil culture�. Later the Americans modified the engines and in the Kittyhawks the engines were more powerful and reliable."

Presumably he means V-1710 from the P-40K which was the mount of a lot of Soviet aces including I think Golodnikov himself. I think one of the reasons he liked the P-40 was he was mostly flying the later types.
...
"N. G. So they say. Normally, pitch and throttle are coordinated in the following manner: more RPMs�reduce pitch. This is how the linked system worked. However, when we were trying to overtake the enemy in a dive or conversely to break away, for maximum acceleration we needed to increase RPMs sharply. Initially the propeller was loaded up and only later was pitch reduced. If in a dive, with the increase of RPMs the propeller pitch was reduced immediately, the propeller would begin to function as a brake. German aircraft were good in the dive. In a fighter with a linked throttle-pitch system in a dive we either fell back or he caught up to us. Therefore we always preferred a separated or de-linked system."
....
"N. G. I say again, the P-40 significantly outclassed the Hurricane, and it was far and away above the I-16.

Personally speaking, the P-40 could contend on an equal footing with all the types of Messerschmitts, almost to the end of 1943. If you take into consideration all the tactical and technical characteristics of the P-40, then the Tomahawk was equal to the Bf-109F and the Kittyhawk was slightly better.

Its speed and vertical and horizontal maneuver were good. It was fully competitive with enemy aircraft.

As for acceleration, the P-40 was a bit heavy, but when one had adjusted to the engine, it was normal.

When the later types Bf-109G and FW-190 appeared, the P-40 Kittyhawk became somewhat dated, but not by much. An experienced pilot could fight an equal fight with it.

I flew somewhere around 50 combat sorties and participated in 10�12 aerial engagements in the P-40. Then the regiment became the next in line to replace its equipment�for the P-39 Airacobra."

This last quote refers to engine modification improving acceleration.

S

 

[Schweik]

Trouble with this is if the engine was "pushed" in the morning and then flew in the afternoon did they really have time to clean the morning oil stains of and repaint the area behind the exhaust stacks before an afternoon flight?

Sometimes due to weather no flying was done for days at a time and at other times several missions were flown in one day.

Yes I'm aware - I don't really know how they could distinguish but apparently they could. I know that leaked oil would often get on the windscreen so they may have at least wiped them down between sorties even if they were doing 3 or 4 a day as they certainly sometimes did.

S

 

[Schweik]

A little bit more from Golodnikov on throttle settings etc.

"In horsepower, of course, it would have been nice to have more power in the P-40 air frame. But the genuinely noticeable deficiency of thrust-to-weight ratio became palpable only toward the end of 1943.

A. S. Was there a special high-output regime?

N. G. There was no supercharger per se, but it had a special regime called �full rich��which delivered an enriched fuel mixture. This capability was employed to achieve especially high output, and this system was not abused. The mixture selector had three positions. MIN [minimum] was for economical flight. AUTO RICH was for normal flight. FULL RICH was for maximum power. The majority of flights were executed on AUTO. Over the ocean or during routine patrols we normally placed the selector at a position midway between AUTO and MIN. This was both economical and enabled us to maintain sufficiently high speed.

A. S. Could these regimes be used at all altitudes?

N. G. Yes, all altitudes. The engine smoked a bit on FULL RICH, but the power was there.

A. S. Was this engine capable of higher altitudes than the Hurricane�s engine?

N. G. Somewhat; we could freely climb up to 8,000 meters. It was particularly good at 4,000�5,000.

A. S. What about the propeller?

N. G. The P-40 had two types of propeller. With the electric propeller, the pitch was regulated by an electric motor, and with the mechanical propeller, conventionally with levers and rods. The electric propeller was automatic, with combined control by the throttle and pitch. The throttle quadrant had a rheostat and the movement of the lever automatically regulated the pitch. The Tomahawk had the electric propeller, while the latest Kittyhawks had mechanical propellers. Both types of propeller were reliable."

 

[Schweik]

I just found another very interesting excerpt from that Golodnikov interview which for some reason was left off of the article on that lend-lease air force website. It's clearly the same interview though.

The book is Barbarossa and the Retreat to Moscow: Recollections of Soviet Fighter Pilots. It's on google books here.

Pages 130-131

I think it highlights the strengths of the P-40 against the Bf 109 and especially in comparison to the Hurricane, this is almost exactly the conclusion I had come to from reading a lot of other interviews, but I'd never seen as concrete of an example.

"An example of the P-40 in action/ One time we were flying Tomahawks. Four of us engaged six Bf 109Fs and shot down three without losing one of our own. We did this employing correct tactics and the aircraft did not fail us. Here's how it went. We were flying at an altitude of 3,000-4,000m. The Germans in the bf 109Fs were 500m lower. We attacked them with surprise, out of the sun, at a good speed. They never saw us. We shot down two in the first pass, leaving four. They reacted appropriately, dispersing in pairs and attempting to engage us in battle in the vertical plane, counting on the superiority of the Messer in this manoeuvre. We also split up and entered the battle 'pair versus pair'. This was our kind of fight! We shot down the third right away, since the P-40 did not lag behind in the vertical (we had a good reserve of speed) and was superior to the Messer in horizontal combat. Their will to fight quickly left them. They split up, went to full power, and broke away in a steep dive.

If we'd been flying Hurricanes, we wouldn't have been able to impose such an active and aggreessive combat. The main strength of the P-40 was its speed.

I shot down a Bf 109F. I was a wingman and the German pilot attacked my leader. He failed to see me or just didn't take me into account (I think that he just didn't see me). I noticed him from far away. I saw him attacking my leader. I had quite good experience and knew the habits of German pilots well. If I'd been less experienced, I'd have opened covering fire, just repelled the German, but I decided to shoot him down. I calculated when he would open fire and planned my manoeuvre so that I'd catch him. Of course it was a serious risk. If I made a mistake, i would have lost my leader - an infamy that would always live with you! So I had to manoeuvre in a way that I'd not lose my leader and open covering fire at any moment. In general, when the German was in the position to fire 100m behind my leader, i was 25m behind the German. I opened fire: two large calibre machine guns at point-blank range. It sounds like a long story to tell, but in the battle this all lasted just a few seconds."

I think what he means specifically in talking about 'the main strength of the P-40 was its speed" is in reference to dive speed. The Hurricane couldn't dive quickly. Aside from dive speed the Russian pilots (including Golodnikov) noted that the P-40 was pretty slow in acceleration, unless 'pushing' the engine.

There is also a bit more about the hurricane which he compares to "flying a pterodactyl" due to it's ponderous handling.

 

[MiTasol]

The p 40 was too heavy and its climb rate too slow to be equal to the 109. Canadian P 40 ace Stocky Edwards had a chance to fly both and he considered the 109f superior. He states that it was difficult to fly the Kittyhawk to its strengths and lateral instability and jamming guns made it tough to succeed in combat involving violent aerial manueovres.

Slaterat

The one thing that all these comparisons that I have seen is they fail to identify which models of each aircraft.
Gun jamming was a problem not only on P-40s but also on almost all US aircraft. Given some of the cartoons on the subject the main problem was sloppy handling of the assembled belts

 

[Schweik]

The one thing that all these comparisons that I have seen is they fail to identify which models of each aircraft.
Gun jamming was a problem not only on P-40s but also on almost all US aircraft. Given some of the cartoons on the subject the main problem was sloppy handling of the assembled belts

James "Stocky" Edwards also specifically mentioned that the P-40K cured most of these problems he had with the P-40E - esp. lateral instability, which was an issue at takeoff and in requiring the frequent use of trim tabs when changing speed, but also the issue with gun stoppages which was gradually fixed (in late model E and K on out) by some changes made starting in 1942.

As you noted that was also an issue with Wildcats, early Hellcats and Corsairs, and even to some extent with P-51s. I'm not sure they ever fully resolved it but changes in how the ammunition was stored (plus probably improvements in the maintenance culture) seem to have greatly alleviated the problem by late 1942.

S

 

[Schweik]

Ok so I've been thinking about a couple of questions based on that new Golodnikov interview excerpt. Maybe people here can answer.The Soviets repeatedly mention removing the wing guns (at least in some squadrons) from P-40B/C Tomahawks, but I've never seen a photo of one without wing guns. In general I'm wondering what a "Field Mod" Tomahawk of the type Golodnikov describes would really be like.

EDIT: Does this one have wing guns?

• Do any of you know of a photo of a Soviet Tomahawk with wing-guns removed?
• How hard could you overboost or overrev one of those early V-1710 on the Tomahawk ?
• How much weight savings would removing the 4 .30 cal wing guns and their ammo, charging systems and so on give you.
• What kind of performance increase would that translate to?
• Did the RAF or Americans ever remove any wing guns in Tomahawks? (I know this was done in Kittyhawk / Warhawks)

I can guess as to all these but just wondering what other peoples opinions might be.

S

 

[tomo pauk]

Amazing - the P-40 with number 58, as the type was represented in the PG3

 

[Schweik]

Amazing - the P-40 with number 58, as the type was represented in the PG3

Forgive my ignorance - what is PG3? Page 3?

EDIT: Another possible candidate though i can't tell

It's probably just hidden by the dark area of the fuselage but I thought I would throw it out there.

 

[Greg Boeser]

Since the .30 barrels protruded from the wings of the P-40B and C, these are apparently gun free wings. At least #58. The one above appears to have barrels protruding.

 

[tomo pauk]

Forgive my ignorance - what is PG3? Page 3?

Panzer General 3 'Scorched earth', turn-based strategy game dealing with ww2. I've played and modded it a lot.

 

[Schweik]

Noticed this interesting tidbit on wiki today. It is taken from Shores MAW vol 1

"On November 22, 1941 there was a significant engagement in which the Tomahawk was put to a hard test by the Bf 109F. At 1540 nine Tomahawks of No. 112 Squadron RAF were joined by thirteen Tomahawks of No. 3 Squadron RAAF for an offensive sweep over the Tobruk-El Adem area[7]. At roughly 1600 hours they were intercepted near Bir Hacheim by 20 Bf 109Fs attacking from 3,000 feet above [8]. During the subsequent hour long engagement, which took place near two German airfields, JG 27 fighters landed and refueled to rejoin the fight. In the melee DAF fighters claimed three Bf 109s shot down and four "probables", while JG 27 claimed 11 P-40s [9]. The actual losses were 6 Bf 109F-4s and 7 Tomahawk IIbs shot down and 1 badly damaged (the aircraft of future RAAF Ace Bobby Gibbes) [10]. In the aftermath of the bloody fight both sides were shaken. The Germans believed they had come out ahead but felt the losses were unacceptable , and therefore made the decision not to dogfight the Tomahawk with the Bf 109F in the future [11], and instead to rely on 'boom and zoom' tactics[12], which while effective, imposed certain Tactical limitations."

Between Bf 109F-4 vs. P-40 B/C I wouldn't have expected quite those results. 3 RAAF and 112 RAF were good squadrons, and Aces Neville Duke and Bobby Gibbes made claims that day so maybe that is part of the formula for (relative) success here.