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

[pbehn]

Per Edwards Park in his book "Angels Twenty" form up was easy, planes took off in pairs, with the next pair starting takeoff roll as the previous pair were about halfway down the runway. Lead pair took a very wide swing to vector to target. Next pair took a little narrower swing, and on down through the last (8th) pair taking a short swing with all 16 planes in the squadron being in formation. Switch to drop tank was after gear/flaps were up and climb speed established.

What do you mean "target"? are you off to Berlin on your own? Are there any clouds in your scenario? Or other escort squadrons?

 

[P-39 Expert]

I do not know if the following has been posted in this thread before, but for what it is worth:

View attachment 633283
View attachment 633284

Have fun.

Thanks for posting. Hmmm, nowhere in these instructions from the flight manual is there mention of using the Takeoff, Climb and Landing chart to compute range. Nowhere. These instructions say to use the Flight Operations Instruction chart and refer to "Operating Data" which is a part of the Flight Operation Instruction Chart. Operating Data is a little more than halfway down the chart in each column. No mention of the Takeoff, Climb and Landing chart at all.

 

[P-39 Expert]

Just as an aside, could there have been an engine, post war, that could have been mounted in the P-39 airframe that would give it claimed performance? Not talking Reno Racers.
I was even thinking of the jet engine that the Bee-Dee 5 had.

Nothing post war, but during the war the V-1710-85 engine in the P-39N gave performance sufficient to meet the guarantee. P-39N began production in November 1942. The V-1710-93 was the two stage model that was in production from April 1943 that would have given the P-39 (and P-40) excellent performance at high altitude.

 

[pbehn]

Nothing post war, but during the war the V-1710-85 engine in the P-39N gave performance sufficient to meet the guarantee. P-39N began production in November 1942. The V-1710-93 was the two stage model that was in production from April 1943 that would have given the P-39 (and P-40) excellent performance at high altitude.

You have made this point before and been given a list before of all the planes of superior performance that were in production before your P-39N, seriously, what is the point. Both the USA and British had Merlin engined P-51s flying before the end of Nov 1942. Then there are P-47s, P-38s, Griffon Spitfires, Spitfire Mk VII, VIII and Mk IX and of course the P-51A or P410 as I now prefer to call it.

 

[Shortround6]

Great, now what about squadrons 2 & 3 of the fighter group?
Mechanical difficulty in one plane?

At just over 70 Degrees F it takes a P-39Q with drop tank just over 2000ft to go wheels up (off the ground) and over 3000ft to get to over 50ft at sea level, even a few hundred feet starts to make a difference.
I don't know how many seconds but if it takes 2000ft to get up to flying speed things aren't moving that quick.

In the tropics it need greater distances. Even in England on a warm summer morning you could need more distance.

But P-39s can form up group sized formations ever so much quicker than the British could with Spitfires in 1940, right?

 

[FLYBOYJ]

Switch to drop tank was after gear/flaps were up and climb speed established.

Vx or Vy?

 

[FLYBOYJ]

Thanks for posting. Hmmm, nowhere in these instructions from the flight manual is there mention of using the Takeoff, Climb and Landing chart to compute range. Nowhere. These instructions say to use the Flight Operations Instruction chart and refer to "Operating Data" which is a part of the Flight Operation Instruction Chart. Operating Data is a little more than halfway down the chart in each column. No mention of the Takeoff, Climb and Landing chart at all.

And just because it doesn't mention it that doesn't mean you ignore it!

Those who had an inkling of flight training would know this, even "Joe Pilots."

Take off/ landing, OK, BUT NOT CLIMB!!!!

It's great you read the manual!

 

[FLYBOYJ]

Nothing post war, but during the war the V-1710-85 engine in the P-39N gave performance sufficient to meet the guarantee. P-39N began production in November 1942. The V-1710-93 was the two stage model that was in production from April 1943 that would have given the P-39 (and P-40) excellent performance at high altitude.

What Guarantee? The one made back in 1940?

 

[FLYBOYJ]

I have asked the expert when the USAAF discovered this was happening and what was done about it, but he didn't know. Is there any evidence this affected the P-39 in US service? The RAF did find a fix, apparently, but I don't know what it entailed.

It would be interesting to find out. Losing the accuracy of your compass would have been a huge issue during this period if you had no electronic navigation aid installed, to find your way home would have been totally dead reckoning.

 

[pbehn]

Great, now what about squadrons 2 & 3 of the fighter group?
Mechanical difficulty in one plane?

At just over 70 Degrees F it takes a P-39Q with drop tank just over 2000ft to go wheels up (off the ground) and over 3000ft to get to over 50ft at sea level, even a few hundred feet starts to make a difference.
I don't know how many seconds but if it takes 2000ft to get up to flying speed things aren't moving that quick.

In the tropics it need greater distances. Even in England on a warm summer morning you could need more distance.

But P-39s can form up group sized formations ever so much quicker than the British could with Spitfires in 1940, right?

Most WW2 UK airfields were constructed with 3 runways in a triangle, all of these runways were at a right angle to Berlin, well know internet fact. Planes could always take off into a headwind and turn right or left to the "target". The start of the BoB was fought in a glorious summer with clear skies, by September the LW was cursed with headwinds going to London, in the previously discussed October Jabo raids on London it was eventually the weather that called a halt, though there were many days in October that meant nothing happened. If you form up in close formation and climb into clouds you start hitting each other, I am not a pilot and I know that. Having climbed through cloud you have to find each other. The P-39N started to be introduced in November, so lets have some procedure for take off that takes into account November weather in UK.

 

[Glider]

Most WW2 UK airfields were constructed with 3 runways in a triangle, all of these runways were at a right angle to Berlin, well know internet fact. Planes could always take off into a headwind and turn right or left to the "target". The start of the BoB was fought in a glorious summer with clear skies, by September the LW was cursed with headwinds going to London, in the previously discussed October Jabo raids on London it was eventually the weather that called a halt, though there were many days in October that meant nothing happened. If you form up in close formation and climb into clouds you start hitting each other, I am not a pilot and I know that. Having climbed through cloud you have to find each other. The P-39N started to be introduced in November, so lets have some procedure for take off that takes into account November weather in UK.

A small point of interest. In the UK there were two basic designs for airfields. Bomber bases had three runways and fighter fields had two. There were exceptions but they were few and far between.
The airfield close to where I live is one of those exceptions which is one reason why it housed the Turbinlite Bostons.

 

[tyrodtom]

Per Edwards Park in his book "Angels Twenty" form up was easy, planes took off in pairs, with the next pair starting takeoff roll as the previous pair were about halfway down the runway. Lead pair took a very wide swing to vector to target. Next pair took a little narrower swing, and on down through the last (8th) pair taking a short swing with all 16 planes in the squadron being in formation. Switch to drop tank was after gear/flaps were up and climb speed established.

What you're reading there is the dumbed down version of what they did, probably the publisher told the author " damn man, they don't have to know every detail " or something similar .
Can you imagine how far downrange the first pair would be by the time the last pair took off ?
It'd take a mighty wide turn by the early aircraft to compensate for that.
Could only work in perfect weather, wide enough runway, and small number of aircraft.
How good do you think the taking off two by two idea works on a gusty day ?
How much luck do you think the late aircraft would have finding the early aircraft on a cloudy day ?

 

[GregP]

Nothing post war, but during the war the V-1710-85 engine in the P-39N gave performance sufficient to meet the guarantee. P-39N began production in November 1942. The V-1710-93 was the two stage model that was in production from April 1943 that would have given the P-39 (and P-40) excellent performance at high altitude.

No it wouldn't have, because there is not room in the P-39 airframe for a two-stage Allison.

There MIGHT be room for a 2-stage Merlin (a bit shorter), but the Merlin was never considered for the P-39, nor would it have been. The P-39 was an American airplane. The Merlin got into the P-51 simply because the British specified the P-51 and it WASN'T strictly an American airplane. You didn't see an Allison in a British airplane, other than the one (P-51) spawned in the U.S.A., did you?

Also, the Merlin was never built in a remote drive configuration like the E-series Allison was.

You have been told this repeatedly, by someone with access to actual P-39s. In fact, there are TWO P-39s at Chino airport, and neither of them have room for a 2-stage Allison engine. My thoughts are that since the P-39 were mass-produced, there wasn't room for a 2-stage Allison in ANY of them. When they needed a 2-stage Allison, they built the P-63, so it would fit. Maybe that's another 150-page thread, though.

Just saying.

 

[wuzak]

Per Edwards Park in his book "Angels Twenty"

Was that a factual book or fiction?

 

[GrauGeist]

What Guarantee? The one made back in 1940?

I had to laugh at that.
It takes a manufacturer over two years to meet (barely) a promised performance level, during a war no less.
And then waiting another several months for a better engine to be developed.
Meanwhile, the war's half over and more advanced types are already in use...

 

[FLYBOYJ]

"Taking off in pairs." Great on a training flight. Go to 0.45.

 

[FLYBOYJ]

Great, now what about squadrons 2 & 3 of the fighter group?
Mechanical difficulty in one plane?

At just over 70 Degrees F it takes a P-39Q with drop tank just over 2000ft to go wheels up (off the ground) and over 3000ft to get to over 50ft at sea level, even a few hundred feet starts to make a difference.
I don't know how many seconds but if it takes 2000ft to get up to flying speed things aren't moving that quick.

In the tropics it need greater distances. Even in England on a warm summer morning you could need more distance.

But P-39s can form up group sized formations ever so much quicker than the British could with Spitfires in 1940, right?

Pray for a headwind!

 

[nuuumannn]

When they needed a 2-stage Allison, they built the P-63, so it would fit.

Correct, Greg. The P-63 was built because of the limitations of the P-39. The mere existence of the P-63 makes a bit of a mockery of the claims made about the P-39's suitability for roles it was not considered for in reality.

 

[buffnut453]

Great, now what about squadrons 2 & 3 of the fighter group?
Mechanical difficulty in one plane?

At just over 70 Degrees F it takes a P-39Q with drop tank just over 2000ft to go wheels up (off the ground) and over 3000ft to get to over 50ft at sea level, even a few hundred feet starts to make a difference.
I don't know how many seconds but if it takes 2000ft to get up to flying speed things aren't moving that quick.

In the tropics it need greater distances. Even in England on a warm summer morning you could need more distance.

But P-39s can form up group sized formations ever so much quicker than the British could with Spitfires in 1940, right?

Yeah...it's all well and good for a single fighter squadron operating independently....not so good for a Wing or Group-sized formation.

Also bear in mind that airfields in the southern UK were very close together. In Cambridgeshire, for example, you can hardly go 8 miles in any direction without hitting the site of a former WW2 airfield. There's a reason why so much attention was paid to forming up.

And, as others have noted, add cloud to the mix and things get a whole lot more complicated. The first aircraft to take off MUST wait above the clouds for the rest of the formation to catch up. Formation flying through cloud is a mug's game.

 

[Ascent]

Yeah...it's all well and good for a single fighter squadron operating independently....not so good for a Wing or Group-sized formation.

Also bear in mind that airfields in the southern UK were very close together. In Cambridgeshire, for example, you can hardly go 8 miles in any direction without hitting the site of a former WW2 airfield. There's a reason why so much attention was paid to forming up.

I can attest to this as a Cambridgeshire resident. I have a cycle route I do occasionally, it's about 40 miles in a loop and takes me right past 5 WWII bomber bases. If I get in my car a half hours drive will take me to a dozen more.