What do you think of the bell p-39 was it a good dogfighter

[FLYBOYJ]

Yep - When the P-38 started experiencing compressibility problems Wright Patterson engineers tried to put their 2 cents in. One recommendation was the installation of the elevator mass balance commonly seen on the P-38s tail. I attended a Lockheed Management club dinner back in 1982 and Kelly Johnson was the guest speaker. He said the mass balance does nothing and he agreed to install them just to shut up the AF engineers!

 

[delcyros]

A problem for the P-39 was the comparably heavy weight. The VVS usually removed cockpit armor and took on further weight saving measures, from which the airplane benefitted, esspeccially at low alt.

 

[FLYBOYJ]

A problem for the P-39 was the comparably heavy weight. The VVS usually removed cockpit armor and took on further weight saving measures, from which the airplane benefitted, esspeccially at low alt.

Did they removed all the armor?

 

[wmaxt]

Yep - When the P-38 started experiencing compressibility problems Wright Patterson engineers tried to put their 2 cents in. One recommendation was the installation of the elevator mass balance commonly seen on the P-38s tail. I attended a Lockheed Management club dinner back in 1982 and Kelly Johnson was the guest speaker. He said the mass balance does nothing and he agreed to install them just to shut up the AF engineers!

Not just to shut them up - the AAF threatened to stop the contract as they were convinced that was the cause of the tail buffet, compressability showed up at the same time but was a different issue. The introduction of the root fillets at the wing/gondola juncture smothing the airflow fixing the buffet. Incidentaly the roll down side windows did the same thing when they were opened.

wmaxt

 

[FLYBOYJ]

Yep - When the P-38 started experiencing compressibility problems Wright Patterson engineers tried to put their 2 cents in. One recommendation was the installation of the elevator mass balance commonly seen on the P-38s tail. I attended a Lockheed Management club dinner back in 1982 and Kelly Johnson was the guest speaker. He said the mass balance does nothing and he agreed to install them just to shut up the AF engineers!

Not just to shut them up - the AAF threatened to stop the contract as they were convinced that was the cause of the tail buffet, compressability showed up at the same time but was a different issue. The introduction of the root fillets at the wing/gondola juncture smothing the airflow fixing the buffet. Incidentaly the roll down side windows did the same thing when they were opened.

wmaxt

Yep - I heard that many AAF brass were continually threatening to cancel P-38 production if the compressibility probelm wasn't addressed. When it was proved that the tail buffet and the compressibility problems were 2 different things, the mass balances stayed. Johnson wanted to issue an EO to remove the balances, Bob Gross, the Lockheed President at the time sided with the Army.

 

[JamesBlonde]

From what I hear the P-39 was a bi of a dud. It got a reputation as a deathtra amongst USAAF cadets who flew it over Arizona etc due to the fact that it was difficult to know when the a/c was going to stall. Apparently it gave little or no warning and was qite difficult to recover due to the c of g problems inherent with the placement of the engine.

However treated right and flown with the professional hand it was, nevertheless, an effective machine (Then again so was the Gloster Gladiator).

Basically I consider the '39 to be an inferior machine but we all know that it isn't the machine so much in A2A combat.

 

[DerAdlerIstGelandet]

A problem for the P-39 was the comparably heavy weight. The VVS usually removed cockpit armor and took on further weight saving measures, from which the airplane benefitted, esspeccially at low alt.

Did they removed all the armor?

I hope they removed more than just the cockpit armor. That would mess up the CG of the aircraft!

 

[FLYBOYJ]

I hope they removed more than just the cockpit armor. That would mess up the CG of the aircraft!

Great point Adler! There have been incidents where armor was removed from restored warbirds with disasterous results!

 

[DerAdlerIstGelandet]

I can believe it. A lot of people underestimate how dangerous the CG can be if it is not correct.

They dont realize how much removing 20 pounds here will effect the balance and overall handeling of an aircraft that weighs 5000lb.

 

[JamesBlonde]

I think I may have mentioned that the G of G ws already in a bad way due to the engine placement. Removing a bit of armour shouldn'y make much difference.

I heard a similar tale from 111 sqn (BEF) in France 1940 abut a hurri pilot who put salvaged armour from a Do-17 behind the seat of his a/c. The authorities frowned upon the liberties he took citing that this would interfere with the C of G. Funnily enough nothing more was heard of the matter after said pilot did a rather impressive aerobatics display infront of the staff who questioned his decision. It wasn't long before the whole sqn followed his lead and installed armour.

Some of you have probably heard this before. Personally I think that taking any armour OUT of the P-39 is a bad idea since with an a/c as bad as that you might need all the help you can get!

 

[plan_D]

That was 1st Squadron, not 111th Squadron. Every Hurricane thereafter had seat armour.

 

[lesofprimus]

Cool info....

 

[FLYBOYJ]

Removing a bit of armour shouldn'y make much difference.

I hate to say it James but that is wrong. As little of 5 pounds removed or added can shift the center of gravity out of limits. If the aircraft gives little or no stall warning, this could be disastrous during landing and especially if a green pilot is flying.

This is 4x more critical on helicopters, just ask Adler!

 

[DerAdlerIstGelandet]

Removing a bit of armour shouldn'y make much difference.

I hate to say it James but that is wrong. As little of 5 pounds removed or added can shift the center of gravity out of limits. If the aircraft gives little or no stall warning, this could be disastrous during landing and especially if a green pilot is flying.

This is 4x more critical on helicopters, just ask Adler!

That is absolutely true! On helicopters if the CG is only a little bit out it completly changes the flight characteristics of the aircraft. For instance it can make it harder to pull out of a roll or a sharp turn, which can be very deadly.

We actually had our whole fleet grounded shortly after we got back from Iraq because we had removed the ballistic armour installed while we were there but there were areas around the cockpit that could not be removed so there was like 80 extra pounds in the cockpit. This screwed up our CG way crazy and our QC shop and the Lar had to figure out a way to modify the aircraft to get the CG into limits. Eventually we were able to get the stuff out and work something out. All is good now!!!

 

[wmaxt]

You have to take into consideration where in relation to the CG the weight is. 5 pounds in the tail is may affect the CG more than 100lbs 1 foot aft of the CG.

In the P-39 the armor was very close to the CG and made little if any difference in it. Modified P-39s were very fast, after the war they won many air races. Speeds comparable to P-38s anf F2Gs and normaly faster than the P-51s until the more modified P-51s started showing up.

In the hands of a good pilot it was pretty effective and quite maneuverable, though it had been hurt badly by the Engineers at Wright Patterson AB with "It looks Good" engineering. When used in a way that matched it's capabilities it was an effective aircraft!

wmaxt

 

[FLYBOYJ]

You have to take into consideration where in relation to the CG the weight is. 5 pounds in the tail is may affect the CG more than 100lbs 1 foot aft of the CG.

In the P-39 the armor was very close to the CG and made little if any difference in it. Modified P-39s were very fast, after the war they won many air races. Speeds comparable to P-38s anf F2Gs and normaly faster than the P-51s until the more modified P-51s started showing up.

In the hands of a good pilot it was pretty effective and quite maneuverable, though it had been hurt badly by the Engineers at Wright Patterson AB with "It looks Good" engineering. When used in a way that matched it's capabilities it was an effective aircraft!

wmaxt

I agree for the most part however even with the armor close to the CG, I believe the CG envelope of the 39 was only a few inches. Removing the armor and flying the aircraft full of fuel or with minimal fuel could produce undesirable results. I would like to get my hands on a P-39 W&B chart and find out how much armor was actually carried on the -39....

The post war 39s and 63s were very fast and when they were modified, and I'm sure that when armor and guns were removed, in some cases ballast had to be added as well.

 

[FLYBOYJ]

You have to take into consideration where in relation to the CG the weight is. 5 pounds in the tail is may affect the CG more than 100lbs 1 foot aft of the CG.

In the P-39 the armor was very close to the CG and made little if any difference in it. Modified P-39s were very fast, after the war they won many air races. Speeds comparable to P-38s anf F2Gs and normaly faster than the P-51s until the more modified P-51s started showing up.

In the hands of a good pilot it was pretty effective and quite maneuverable, though it had been hurt badly by the Engineers at Wright Patterson AB with "It looks Good" engineering. When used in a way that matched it's capabilities it was an effective aircraft!

wmaxt

I agree for the most part however even with the armor close to the CG, I believe the CG envelope of the 39 was only a few inches. Removing the armor and flying the aircraft full of fuel or with minimal fuel could produce undesirable results. I would like to get my hands on a P-39 W&B chart and find out how much armor was actually carried on the -39....

The post war 39s and 63s were very fast and when they were modified, and I'm sure that when armor and guns were removed, in some cases ballast had to be added as well.

Stumbled on this from a former P-39 pilot....

"The center of gravity of the Cobra was exceptionally rearward. We even had 10 kilos of lead weight mounted in the forward portion to unload the tail. Sometimes this center of gravity created problems with the wing and in inverted flight. Once again, during non-combat flights, don't place any load in the empty rear portion of the fuselage. Somebody didn't do it and couldn't make it back. The airplane flew as if balanced on a tip of an awl. Later we gained experience and loaded everything in the forward compartment."

 

[wmaxt]

I agree for the most part however even with the armor close to the CG, I believe the CG envelope of the 39 was only a few inches. Removing the armor and flying the aircraft full of fuel or with minimal fuel could produce undesirable results. I would like to get my hands on a P-39 W&B chart and find out how much armor was actually carried on the -39....

The post war 39s and 63s were very fast and when they were modified, and I'm sure that when armor and guns were removed, in some cases ballast had to be added as well.

The weight and Balance sheet and the armor location/weight charts would tell us if ballast was required.

The P-39 though didn't have issues like the P-51 where the fusalage tank could actually go from one extreme to the other. I've just never heard of serious problems with the P-39 regarding CG issues. Removing the armor was common on P-39s.

My main point is that CG issues could be major but normaly they just need to thought out and approached carefully. It's also true that designers like to place things that change in flight, like fuel, in locations that are nuetral to the CG and things that don't change, like armor, in places that affect the CG more. Research is important here.

wmaxt

 

[FLYBOYJ]

I agree for the most part however even with the armor close to the CG, I believe the CG envelope of the 39 was only a few inches. Removing the armor and flying the aircraft full of fuel or with minimal fuel could produce undesirable results. I would like to get my hands on a P-39 W&B chart and find out how much armor was actually carried on the -39....

The post war 39s and 63s were very fast and when they were modified, and I'm sure that when armor and guns were removed, in some cases ballast had to be added as well.

The weight and Balance sheet and the armor location/weight charts would tell us if ballast was required.

The P-39 though didn't have issues like the P-51 where the fusalage tank could actually go from one extreme to the other. I've just never heard of serious problems with the P-39 regarding CG issues. Removing the armor was common on P-39s.

wmaxt

And I could tell you in "basic pilot 101" reward CG is not a good thing, especially for newer pilots. I also found data that the Russians issued directive to P-39 pilots not to pull out of dives in a left turn...the tail could be pulled off!

 

[wmaxt]

And I could tell you in "basic pilot 101" reward CG is not a good thing, especially for newer pilots. I also found data that the Russians issued directive to P-39 pilots not to pull out of dives in a left turn...the tail could be pulled off!

I agree 100%, and forward CG can get real interesting when you take power off as well. I was never suggesting flying anything out of balance. I was just commenting on the possible effects:

First the effects are variable depending on distance from the CG.

Second is that the pilots armor in a P-39 is very close to the CG.

Third the resulting effect might not be that great. If ballast is required, a 5lb weight in the nose/tail may be enough to countor a reduction of 100lbs, 6 inches off the CG (using examples for discussion here not actual numbers)

I'm more aware of the P-39 than knowledgable and I am not debating that removing the armor may have an effect (other than just weight reduction) or that it might be a lot just that it probably isn't a big deal if it's done right.

wmaxt