"Stretch or not strech" of aircraft designs

[Ivan1GFP]

Gentlemen,

I am fairly certain that the FW 190 in that video sequence was not actually equipped with a BMW 801 engine. The aircraft looks like one of the Flugwerk replicas in which case it is most likely using a copy of a Shvetsov M-82 of some flavor.

- Ivan.

 

[Schweik]

Interesting, it's apparently a Ash-82 from a Tu-2. 1,850 hp, that is probably more than the original.

My respect for the La 5 definitely increases, that has to be one of the most aggressive sounding engines I've ever heard.

 

[Schweik]

It's funny, they are making Yak-9s with Allison engines and Fw 190s with Shvestov engines. Somebody needs to start making some WW2 aircraft engines, there is clearly a market!

 

[Ivan1GFP]

Interesting, it's apparently a Ash-82 from a Tu-2. 1,850 hp, that is probably more than the original.

My respect for the La 5 definitely increases, that has to be one of the most aggressive sounding engines I've ever heard.

Hello Schweik,

If the original is just running military power, than that is true. You can get an idea for the power level in the test of the "FW 190G-3" test I posted a link for above. I believe it was about 1750 HP. With a power adder, expect something closer to 2050 or 2100 HP with Emergency Power. The problem though is that the M-82 in the La-5 / La-7 has a very low time / altitude limit for 1850 HP. The actual useful rating is closer to 1700 HP. (This is with late war versions of each engine.)
The other thing is that from what I have read elsewhere, these engines are mostly Chinese copies intended for Transport aircraft.
The other BIG gotcha is that the oil cooler in the Flugwerk aircraft was relocated to where the cowl guns originally were.
That cures the issue of an oil leak into the hot engine causing a fire as happened with the originals, but it also required the removal of the gun mounts and associated bracing which were a structural member. My understanding is that this significantly reduces the G load the structure can handle which means nothing in airshow flying but is a difference to note.
(In other words, the aircraft may not be quite as aerobatic as you might think.)

Here is a more extreme variant of the replica FW 190A-9/N types: This one is down at the "Fighter Factory" in Virginia Beach. I believe this is the current one. There has been more than one down there, but I don't believe there was more than one at a time.

Here is what I believe is still the only FW 190 still flying with a BMW 801 engine. It is the A-5 model.


In shots that have the cowl in place, compare the shape of the original to the reproductions. The original is much "rounder" and doesn't have the same angles where the side blends into the front. There are a couple more detail differences, one of which is that the original has a gap between the front ring of the cowl and the rest. I believe this is the exit for the cooling air for the oil cooler.

- Ivan.

 

[Ivan1GFP]

The similarity between the engines of the Fighter Factory FW 190 and this Tu 2 are certainly hard to deny!

 

[nuuumannn]

If we are gonna be pedantic about it, the engines are actually Dongan HS-7s built in China, which are licence copies of the ASh-82 - all the Flug Werk '190s are powered by this engine, as far as I know, so the piccie you should be posting of the aircraft powered by one is this!

DSC_6683

Harbin Z-5 licence built Mil Mi-4.

 

[Ivan1GFP]

Hello Nuuumannn,

Agreed about the source for engines for MOST of the Flugwerk FW 190s.
Note however that at least one owned by Rudy Frasca was powered by a Pratt & Whitney R-2800.
Please take a look at the Fighter Factory aircraft. I don't know for certain that what is under the hood isn't a Chinese engine, but they seemed to have gone to an awful lot of trouble to graft on the cowling and propeller to make it look like it came from a Tu-2.

- Ivan.

 

[Schweik]

One thing I noticed in the video, the fw has a three bladed prop with kind of wide blades, like the original. Some of the Tu-2 derived ones have four blade props.

 

[Ivan1GFP]

Hmmm, Yak-9T is the greatest thing since borscht using a 170kg gun that is 341cm long with 30-32 rounds of cannon ammo and a single 12.7mm machine gun (200 rounds) while the Yak-9K using a 170kg gun that is 341cm long with 29 rounds of ammo and a single 12.7mm machine gun (200 rounds) needs escorts?

I am confused

......

The 45 mm round was the 37mm cartridge case necked up. It was the same diameter at the back, there was little difference between the two guns.

Most accounts blame the poor performance of the 9K on the large fuel tanks and greater fuel load.
However most accounts say the 9K was powered by the M-105PF engine that was rated at 1180hp at altitude (?).
As was the 9T.
Weight of the guns and ammo for either the 9T or the 9K might have gone 250-270Kg not including mounts, ammo boxes/chutes, gun heaters and charging system/s.

Hello Shortround6,

I will blame YOU for this little continuation.
I remembered reading your comment above about large fuel tanks and greater fuel load but could not find it in the data table I use the most for a reference. The two versions of the Yak-9 were close enough in specs to be twins off the same production line so there had to be a reason why 2748 Yak-9T were built as opposed to only 53 Yak-9K.
The data table in "Yakovlev's Piston Engine Fighters" suggests that the two aircraft were near twins as far as performance as well, but not all sites agree, so there had to be something else going on.

Here is what I believe was the "Rest of the Story":
The first version of the Yak-9K didn't just swap the big cannon for a bigger cannon.
It also added about 150 KG of extra fuel in the wings.
The larger cannon bore didn't change the weight of the gun, but it did make the BORE of the gun larger of course and even though the barrel wall was made to be very thin where it went through the propeller reduction gear shaft, it still left much less clearance than the 37 mm barrel did.
Recoil was many times higher, but the muzzle brake was fairly efficient and brought the recoil energy down to BELOW that of the NS-37 cannon.
This was still quite severe recoil and was still causing fatigue damage to the airframe just as it was for the NS-37.
My Note:
I suspect that total energy was lower, but the impulse and peak force was still higher. The vibrations from firing also probably brought the cannon barrel into contact with parts of the propeller reduction gear because the clearance was on the order of fractions of a millimeter.
The performance with the extra fuel tanks was so poor that they were removed and the weight became comparable to the Yak-9T.
Even without the extra fuel, the pilots felt that these aircraft were too heavy to be ideal for fighting other fighters and should work in combination with Yak-3 or Yak-9U.
The effectiveness of the NS-45 in aerial combat was actually better than the NS-37. On average, 10 shots were fired per kill as compared to about 30 shots per kill for the 37 mm.
The problem though was that the NS-45 also had very poor reliability and that was the real reason that the aircraft never went into production.

- Ivan.

 

[Ivan1GFP]

One thing I noticed in the video, the fw has a three bladed prop with kind of wide blades, like the original. Some of the Tu-2 derived ones have four blade props.

Hello Schweik,

I believe Nuuumannn is generally correct. I was following the Flugwerk aircraft very early on and the engines that were being used were Chinese made, not Soviet. I heard it mentioned that they were crate motors intended for transport aircraft. I just didn't realize those "transport aircraft" were really helicopters!

Another difference is that the engine cooling fan is running at propeller speed and not faster as it would be on the BMW 801, but then again, it doesn;t have to blow air through an oil cooler either.

As for replacement engines, don't forget the many A6M that are using Pratt & Whitney R-1830s.

- Ivan.

 

[pinehilljoe]

though it happened post war, the B-29 evolving into the B-50 was a successful stretch.

 

[Schweik]

Hello Shortround6,

I will blame YOU for this little continuation.
I remembered reading your comment above about large fuel tanks and greater fuel load but could not find it in the data table I use the most for a reference. The two versions of the Yak-9 were close enough in specs to be twins off the same production line so there had to be a reason why 2748 Yak-9T were built as opposed to only 53 Yak-9K.
The data table in "Yakovlev's Piston Engine Fighters" suggests that the two aircraft were near twins as far as performance as well, but not all sites agree, so there had to be something else going on.

Here is what I believe was the "Rest of the Story":
The first version of the Yak-9K didn't just swap the big cannon for a bigger cannon.
It also added about 150 KG of extra fuel in the wings.
The larger cannon bore didn't change the weight of the gun, but it did make the BORE of the gun larger of course and even though the barrel wall was made to be very thin where it went through the propeller reduction gear shaft, it still left much less clearance than the 37 mm barrel did.
Recoil was many times higher, but the muzzle brake was fairly efficient and brought the recoil energy down to BELOW that of the NS-37 cannon.
This was still quite severe recoil and was still causing fatigue damage to the airframe just as it was for the NS-37.
My Note:
I suspect that total energy was lower, but the impulse and peak force was still higher. The vibrations from firing also probably brought the cannon barrel into contact with parts of the propeller reduction gear because the clearance was on the order of fractions of a millimeter.
The performance with the extra fuel tanks was so poor that they were removed and the weight became comparable to the Yak-9T.
Even without the extra fuel, the pilots felt that these aircraft were too heavy to be ideal for fighting other fighters and should work in combination with Yak-3 or Yak-9U.
The effectiveness of the NS-45 in aerial combat was actually better than the NS-37. On average, 10 shots were fired per kill as compared to about 30 shots per kill for the 37 mm.
The problem though was that the NS-45 also had very poor reliability and that was the real reason that the aircraft never went into production.

- Ivan.

interesting theory but that is basically speculation.

 

[Ivan1GFP]

interesting theory but that is basically speculation.

Only one part is speculation and I commented it as "My Note:"

- Ivan.

 

[Shortround6]

On the engine used by the reproduction Fw 190s,

From Wiki so take as you will.

"ASh-82V (M-82V) - Helicopter version of the ASh-82T developed in 1952, with axial-flow fan mounted in the fuselage's front. The engine was connected to a R-5 two-stage planetary primary gearbox with the help of a shaft (which was between the pilots seats). This engine was used in the Mi-4 and Yak-24 helicopters.[4] "

Bolding in the body of the text is by me.

"Dongan HS-7 A Chinese license built copy of the ASh-82V, and the chosen engine for powering modern 21st century reproductions of the Focke-Wulf Fw 190A built in Germany.[citation needed] "

"Dongan HS-8 A modified version of the Dongan HS-7 which "combined the main body and supercharger of the HS-7 with the reduction gear and propeller drive of the Shvetsov ASh-82T".

"ASh-82T (M-82T) - New version of the ASh-82FNV developed in the early fifties for civilian aircraft ............................. A four-blade high efficiency propeller, the Typ AV-50m, was developed for the 82T version. ..............................."
Bolding in the body of the text is by me.

something seems a little off, The engines in the FW 190 reproductions may very well be Dongan HS-7 power sections but reduction gears on helicopter engines were seldom the same as the reduction gears on a fixed wing engine and the reduction gears have to come from somewhere.

Helicopter engine with cooling fan.

ASh-82T with fixed wing reduction gear.

Another picture of the Helicopter engine.

Notice the mounting flange or drive shaft attachment plate in the middle of the fan.
One book claims the helicopter engine had the master clutch in the crankcase nose.

 

[Ivan1GFP]

Hello Shortround6,

Global Security has a couple entries on the HS-7 and HS-8. It seems like the two differ a bit in the power section (obviously) but the difference is only 5.7% of parts. With the correct reduction gear arrangement, there must have been some reason why the HS-8 was not used instead.

- Ivan.

 

[Dimlee]

What was the original topic, again? Ah, well...

Probably, Me 410 is a good example of successful "stretching" of the earlier model and not just in lengthening the fuselage?

Stretching in the Soviet aviation of WWII.
Successful:
LaGG-3 =>LaGG-5/La-5 => La-7 => La-9
Yak-1 => Yak-3
Yak-7 =>Yak-9 with many modifications
VI-100 => Pe-2
Il-2 => Il-10

Probably successful but not proved due to short operational history:
SB-2 => Ar-2

Not successful (IMO):
DB-3 => DB-3F/IL-4
numerous attempts to improve original Il-2

 

[tomo pauk]

What was the original topic, again? Ah, well...

Probably, Me 410 is a good example of successful "stretching" of the earlier model and not just in lengthening the fuselage?

Stretching in the Soviet aviation of WWII.
Successful:
LaGG-3 =>LaGG-5/La-5 => La-7 => La-9
Yak-1 => Yak-3
Yak-7 =>Yak-9 with many modifications
VI-100 => Pe-2
Il-2 => Il-10

Probably successful but not proved due to short operational history:
SB-2 => Ar-2

Not successful (IMO):
DB-3 => DB-3F/IL-4
numerous attempts to improve original Il-2

Yak-3 was probably closer to all-new aircraft, rather than just a modification of the Yak-1. Ditto for the Il-10 vs. Il-2.

 

[Dimlee]

Yak-3 was probably closer to all-new aircraft, rather than just a modification of the Yak-1. Ditto for the Il-10 vs. Il-2.

Not just another modification, of course. I use the term "stretching" here as it was defined in the first post.

 

[tomo pauk]

Not just another modification, of course. I use the term "stretching" here as it was defined in the first post.

I'd still be of the opinion that at least Il-2 and Il-10 were two different aircraft.

 

[Dimlee]

I'd still be of the opinion that at least Il-2 and Il-10 were two different aircraft.

A matter of definition, I think.
According to Oleg Rastrenin (the best expert in the field of VVS attack aircraft, probably), the idea of Il-10(Il-1 initially) was formulated by Ilyishin after the Stalingrad. He asked Shakhurin to approve the concept of the "armoured fighter" developed on the basis of Il-2. GKO decided not to put all eggs in one basket and ordered several (five at least) prototypes of "fighter variant of shturmovik" and of "improved aerodynamic variants". At the end, it was just Il-1(Il-10) which survived but changed its designation from fighter to "shturmovik" and the development continued in three factories already engaged in Il-2 production.
On one hand, Il-10 looked very different from Il-2, indeed, inside and out. I see your point.
On the other hand, it's common in Russian language sources to name Il-10 as "a result of deep modernisation of Il-2" or something like that. And I did not find (so far) any claims about Il-10 development from the "clean sheet", so to say.
Rastrenin himself did not clarify that matter. May be we'll learn more in one of his next books.