Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained) (1 Viewer)

[Greg Boeser]

Even if the guy does not know you are there, unless it is a zero deflection up the kazoo shot, judging angles will be a significant challenge. Even at only 300 mph, in one sec you move 440 ft, during which time you have managed to fire a mere two 37MM rounds, only four rounds in 880 ft. It will be all impossible to correct your fire against airborne targets. I suppose that if you charge up to a bomber formation and let fly with everything you've got you might hit something.

It's too bad we did not have fast firing 15MM cannon like the Germans did in the 109F, or that we never finished developing the .60 caliber machine gun.

I have read of but a few cases of a P-39 hitting anything with the 37MM. below is one:
View attachment 595272

An eyewitness to Major Miller's demise reported that he appeared dead or unconscious as the plane flew in a gradual descending turn. The plane plunged into the water and was gone.
Source: The Aleutian Warriors, Volume I, John Haile Cloe

 

[wuzak]

Trajectory was relatively flat out to 400 yards which was about the outer limit of accuracy with any airborne gun. It was estimated that 60-80% of pilots shot down in WWII were unaware of their assailants so the relatively slow rate of fire would have only mattered in a maneuvering fight. If you were aware of your opponent you could normally escape fighter vs fighter combat unless you had a severe performance disadvantage.

That'd be why Vultee had to come up with an elevating mechanism that allowed the two 37mm to hit the same target as the two 0.50", as well as a new sighting system, when building the XP-54.

 

[P-39 Expert]

That'd be why Vultee had to come up with an elevating mechanism that allowed the two 37mm to hit the same target as the two 0.50", as well as a new sighting system, when building the XP-54.

Always liked the rear engine/propeller concept, thought it should have been developed earlier and further.

 

[Shortround6]

It's too bad we did not have fast firing 15MM cannon like the Germans did in the 109F, or that we never finished developing the .60 caliber machine gun.

Trouble is that the German gun weighed almost exacty what the MG 151/20 and while easier to hit with each shell was much less destructive.

Same goes for the US .60 cal round. You needed a 20mm sized gun to fire it.

.60 cal round on the right next to the standard .50 cal.

 

[spicmart]

What if the P-39 had been given a competitive engine? Aerodynamically it was better than most other fighters.

 

[Glider]

The jammers of 100 Group that flew missions over hostile territory were almost all B-24's and B-17's

Reference: "Confound and Destroy 100 Group and the bomber Support Campaign"

Its Wiki but I see no reason to doubt the detail. B17's and B24's were heavily outnumbered by the other types

Order of battle[edit]

An electronic warfare Fortress III of 214 Squadron with nose-mounted H2S radome
No. 100 Group was headquartered at Bylaugh Hall, Norfolk from January 1944, a central location from which to administer the group's airfields in north Norfolk. No 100 Group operated from eight airfields with approximately 260 aircraft, 140 of which were various marks of Mosquito night fighter intruders with the remainder consisting of Handley Page Halifaxes, Short Stirlings, Vickers Wellingtons, Fortresses and Liberators carrying electronic jamming equipment. The group also operated the Bristol Beaufighter for a short time.
The group disbanded on 17 December 1945. During its existence it had one commander, Air Vice-Marshal Edward Addison.
100 (Special Duties) Group order of battle[4]
SquadronAircraftFirst 100 Group operationBase
192Mosquito II, B.IV, B.XVI, Wellington B.III, Halifax IV December 1943RAF Foulsham
141Beaufighter VI, Mosquito II, VI, XXX December 1943RAF West Raynham
239Mosquito II, VI, XXX20 January 1944 RAF West Raynham
515Mosquito II, VI3 March 1944 RAF Little Snoring, RAF Great Massingham
169Mosquito II, VI, XIX20 January 1944 RAF Little Snoring
214Fortress II, III20/21 April 1944 RAF Sculthorpe, RAF Oulton
199Stirling B.III, Halifax B.III1 May 1944 RAF North Creake
157Mosquito XIX, XXXMay 1944 RAF Swannington
85Mosquito XII, XVII5/6 June 1944 RAF Swannington
23Mosquito VI5/6 July 1944 RAF Little Snoring
223Liberator VI, Fortress II, IIISeptember 1944 RAF Oulton
71Stirling II, Halifax III15 September 1944 RAF North Creake
462 (RAAF)Halifax III13 March 1945 RAF Foulsham

 

[tomo pauk]

What if the P-39 had been given a competitive engine? Aerodynamically it was better than most other fighters.

Performance-wise it would've been an excellent fighter, it was inded a streamlined fighter. With okay-ish V-1710-83 it was doing 385-400 mph.
Problem was that such versions of the V-1710 were late by at least a year (Autumn of 1942 instead of Autumn of 1941), and that Allison never series produced an 1-stage supercharged V-1710 that is comparable with Merlin XX/45/47, DB-601E or the de-rated 605A, while the 2-stage V-1710 was both too late and was too long to easily fit on the P-39. The Packard Merlin required a re-design in order to be installed on the P-39.

(a 1-stage S/Ced V-1710 with, say, 11in or 12in impeller would've been very interesting for the US fighters)

 

[glennasher]

^^^^^^^ The P-39 still had all the other issues that hampered it horribly, though, COG being chief amongst them, speed is a wonderful thing, but it isn't everything.

 

[tomo pauk]

It is probably easier to swallow an issue or two if a fighter does 400 mph than if it does 360 mph, while still having the issues. Especially if the pilot knows what he's doing.

 

[P-39 Expert]

What if the P-39 had been given a competitive engine? Aerodynamically it was better than most other fighters.

It had competitive engines. It was too heavy in the 1942 models (D/F/K/L). Easily corrected at forward airbases by simply removing some redundant or unnecessary items. The 1943 models had uprated -83/-85 engines and performance was competitive even at the heavier 1942 weight.

 

[P-39 Expert]

Performance-wise it would've been an excellent fighter, it was inded a streamlined fighter. With okay-ish V-1710-83 it was doing 385-400 mph.
Problem was that such versions of the V-1710 were late by at least a year (Autumn of 1942 instead of Autumn of 1941), and that Allison never series produced an 1-stage supercharged V-1710 that is comparable with Merlin XX/45/47, DB-601E or the de-rated 605A, while the 2-stage V-1710 was both too late and was too long to easily fit on the P-39. The Packard Merlin required a re-design in order to be installed on the P-39.

(a 1-stage S/Ced V-1710 with, say, 11in or 12in impeller would've been very interesting for the US fighters)

Agree with most of what you say. V-1710 was competitive with contemporary DB (and BMW) engines when weight and displacement were taken into account. The 2-stage V-1710-93 wasn't that late, in production by April 1943 (same time as the first Packard two stage Merlin). And it did fit into a standard P-39 with minor modifications. Engine compartment was the same size as the P-63 which used the V-1710-93.

 

[tomo pauk]

It had competitive engines. It was too heavy in the 1942 models (D/F/K/L). Easily corrected at forward airbases by simply removing some redundant or unnecessary items. The 1943 models had uprated -83/-85 engines and performance was competitive even at the heavier 1942 weight.

Pray tell, what were those competitive engines on the P-39? The very second one suggests removing stuff from aircraft = engines were not competitive.

Agree with most of what you say. V-1710 was competitive with contemporary DB (and BMW) engines when weight and displacement were taken into account.

Weight and size are concerns, unless the power and reliability justify the price of the weight and/or size size. The DB 601/605 engines' weight and size was comparable with 1-stage V-1710.
Displacement is of no concern for either designer of an aircraft, nor it is for the end user. What mattered was power at desired altitude vs. weight and size penalty, and here it took 2-stage V-1710 to match or beat the engines Germans have had in wide scale use in 1942.

The 2-stage V-1710-93 wasn't that late, in production by April 1943 (same time as the first Packard two stage Merlin). And it did fit into a standard P-39 with minor modifications. Engine compartment was the same size as the P-63 which used the V-1710-93.

When one posts a picture of a real P-39 (not the all-new P-39E) with a 2-stage V-1710 installed, I'll buy the story.
What was late when mattered was, at least, the V-1710 with the 'faster' turning impeller (9.6:1 drive ratio vs. 8.8:1).

 

[P-39 Expert]

Pray tell, what were those competitive engines on the P-39? The very second one suggests removing stuff from aircraft = engines were not competitive. Removing unnecessary/redundant weight from an airplane will improve performance on the same engine power.


Weight and size are concerns, unless the power and reliability justify the price of the weight and/or size size. The DB 601/605 engines' weight and size was comparable with 1-stage V-1710. V-1710 had only 79% displacement of a DB605 and 82% of a DB601. Comparable? No replacement for displacement.
Displacement is of no concern for either designer of an aircraft, nor it is for the end user. What mattered was power at desired altitude vs. weight and size penalty, and here it took 2-stage V-1710 to match or beat the engines Germans have had in wide scale use in 1942. Two stage -93 had a critical altitude of 21500', simply move the carb from the auxiliary stage to the engine stage (like P-38 and P-47) and increase critical altitude another 3000'. DB601 critical altitude was 18000'.



When one posts a picture of a real P-39 (not the all-new P-39E) with a 2-stage V-1710 installed, I'll buy the story. P-39E was not all new. Just a P-39D fuselage with the coolant tank reshaped and moved up right behind the pilot and the auxiliary stage installed in it's place. Fuselage was longer because tail cone was lengthened, but engine compartment where the auxiliary stage was located was the same size/length. Posted P-39/P-63 drawings many times, engine compartments are the same size. P-63 had the auxiliary stage, P-39 did not.
What was late when mattered was, at least, the V-1710 with the 'faster' turning impeller (9.6:1 drive ratio vs. 8.8:1). Agree.

 

[Glider]

It had competitive engines. It was too heavy in the 1942 models (D/F/K/L). Easily corrected at forward airbases by simply removing some redundant or unnecessary items. The 1943 models had uprated -83/-85 engines and performance was competitive even at the heavier 1942 weight.

Have you ever heard of Jackanory?

 

[P-39 Expert]

Have you ever heard of Jackanory?

No.

 

[Glider]

Look it up

 

[GrauGeist]

The very second one suggests removing stuff from aircraft...

Yep, it's quite simple really.
Here's how to get the P-39 up to 435mph:
Eliminate the 37mm cannon, eliminate the .50MGs, eliminate all the armor (especially the nose armor), eliminate the V-1710.
Now that it's suitably lightened, tow it behind a P-59 until you've cleared the coast-line and then cut it loose

 

[P-39 Expert]

Look it up

I did.

 

[FLYBOYJ]

Yep, it's quite simple really.
Here's how to get the P-39 up to 435mph:
Eliminate the 37mm cannon, eliminate the .50MGs, eliminate all the armor (especially the nose armor), eliminate the V-1710.
Now that it's suitably lightened, tow it behind a P-59 until you've cleared the coast-line and then cut it loose

And put it into a dive...

 

[Greg Boeser]

Then bail out.