Yak-7b - In case you didn't notice

[LukeFF]

58 minutes ago, Dakpilot said:

Disregarding engine limits for a moment, what are the issues with weights for P-40 and P-39?

 

I would expect these are values/figures that are not up for much interpretation..?

 

The P-39's weights are apparently based on a plane that was fully winterized at the time of its evaluation.

Edited April 10, 2018 by LukeFF

[JtD]

The P-40E-1 with full fuel is given with 3855kg in a British manual and a Soviet manual lists it at 3840kg, in game is modelled at 3819kg. Differences are largely due to ammo load differences. US figures are slightly heavier, 3855kg with the same ammo as in game standard.

The P-39L-1 with full fuel is given with 3508kg in a US manual when equipped with 522 or 535 radio, in game is modelled at 3508kg, so that's obviously the devs source.

[Venturi]

That's assuming we go the Britishized one with "multiple improvements" and extra radiosets, also that it wasn't weighed with any extraneous testing equipment. The Boscombe Down trials planes always seemed to me to have all sorts of "extras" that are occasionally mentioned in asides on random pages of the report, and it is never exactly clear what the totality of these extras are. It is interesting to note the Brits had their own regimen for equipping these aircraft including different radios, and who knows what else. All that is clear to me is that US sources state ~8100 lbs for the aircraft...'

 

http://www.wwiiaircraftperformance.org/P-40/P-40.html

 

(The P40D and E were identical, save the number of guns - 4, vs 6 on the P-40E)

 

 

WAR DEPARTMENT 
AIR CORPS, MATERIEL DIVISION 
Wright Field, Dayton, Ohio 
July 21, 1941

MEMORANDUM REPORT ON 
Pursuit Single Engine P-40D, A.C. No. 40-362

 

Subject:      Acceptance Performance Tests

Section:      Flying Branch

Serial No:   PHQ-M-19-1267-A

 

SUMMARY

 

A.	Purpose
	1.	Report on flight tests conducted at the manufacturer's plant on Curtiss P-40D. Airplane equipped with Allison V-1710-39 engine and 3-bladed constant speed propeller, blade design No. 89301-3, blade angle range 24.5° to 54.5° at 42" radius. Gross weight as tested 7740 lbs., c.g. location, wheels up, 27.9% m.a.c.; whee;s up; wing flaps neutral; radio antenna installed; prestone and oil cooler flaps flush with cowling in level flight, wide open in climb; four 50 cal. wing guns and uncovered blast tubes in plane, except where otherwise stated.
B.	Test Results
	1.	Level flight speed tests:

 

	Altitude Ft.	True Speed MPH	R.P.M.	B.H.P.	Throttle Position
	*5,175	326	3000	1150	Part
	*15,175	354	3000	1085	Wide
	15,175	335	2600	910	Wide
	15,175	307.5	2280	725	Wide
	15,175	290	2200	635	Part
	15,175	265	2100	530	Part
	15,175	239	1900	420	Part
	15,175	209	1700	300	Part

 

4.

Climb data, mixture control in automatic rich position:

WAR DEPARTMENT 
AIR CORPS, MATERIEL DIVISION 
Wright Field, Dayton, Ohio 
September 25, 1941

MEMORANDUM REPORT ON 
Pursuit Single Engine P-40E, A.C. No. 40-384

 

Subject:      Performance

Section:      Flying Branch

Serial No:   PHQ-M-19-1300-A

 

SUMMARY

 

A.	Purpose
	1.	Report on performance of Curtiss P-40E. Airplane equipped with Allison V-1710-39 engine (backfire screens in intake ports) and 3-bladed constant speed propellers, blade design No. 89301-3. Gross weight as tested approximately 8011 lbs. with belly tank removed; c.g. location wheels up 28.5% m.a.c.; landing gear retracted; wing flaps neutral; radio antenna installed; prestone and oil cooler shutters flush with cowling in level flight, wide open in climb; six 50 cal. wing guns with uncovered openings in wings in place. Weight of belly tank and fuel 366 lbs. (capacity 52 gals.).
B.	Test Results
	1.	High speed tests:

 

	Altitude Ft.	True Speed MPH	R.P.M.	B.H.P.	Throttle Position	Test Condition
	11,400	342	3000	1150	Wide	Belly tank removed
	15,300	340	3000	990	Wide	Belly tank removed
	15,300	319	3000	965	Wide	Belly tank installed
	15,300	316	2600	820	Wide	Belly tank removed
	15,300	298	2600	800	Wide	Belly tank installed

ARMY AIR FORCES 
MATERIEL CENTER 
Wright Field, Dayton, Ohio 
April 5, 1943

MEMORANDUM REPORT ON 
Pursuit Single Engine P-40E, A.C. No. 40-633

 

Subject:      Propeller Tests

Branch:       Flight test

Serial No:   FS-M-19-1580-A

 

SUMMARY

 

A.	Purpose
	1.	Report on performance of P-40E airplane, A.C. No. 40-633, equipped with four different propellers, each test being run with a propeller of particular blade design number, hub number, and spinner type as indicated. Airplane equipped with V-1710-39 engine and flown with wing flaps neutral, wheels up, carburetor cold, mixture "auto-rich" except where specified, cowl flaps neutral for level flaps and wide open for climbs. Airplane flown at a gross weight of approximately 8035 pounds with full gas and oil load, belly tank shackles in place, six .50 caliber guns without ammunition (no ballast), provision for spin chute but no spin chute in place. Horsepower figures obtained from power curve V-1710-39 dated December 12, 1941.
B.	Test Results
	1.	High Speeds in level flight.

 

Propeller	Altitude	True Airspeed MPH	b.h.p	RPM
Hub C-532D Blades 89301-3 Std. Spinner	14,900	336.5

[blitze]

Meanwhile back on topic, after having a rough time in my Kuban career as a Spit pilot, I transferred to a mixed Yak unit.

 

After a few missions in the Yak 1B I was tasked to protect troops and was the only one in our flight with a Yak 7.  I was very happy and our first outing together we brought down 3 109's and managed to loose a pair of them who came to help their friends, after I had downed them.  Cloud was at 700m and thick so I was thinking I was in the clear and starting to return to base when I was bounced.  Spent my last ammo lightly hitting one of them and then 5 minutes dancing through the double cloud layer trying to loose my attackers.

 

Success, I was able to hide in the clouds, loose my attacking pair and return to base in 1 piece.  She did get warm and radiator management as well as engine management was crucial through the engagement.  Found Water more important to monitor than Oil which could be set at less open setting.  Also watching throttle, rpm helped and speed as well.  Like the other Yaks, trim plays a big part in speed and energy fighting.

 

A very happy first career mission in her and despite being a razor back, the view behind was quite good.  Took a few minutes in flight to work out what was what with the instrument panel.

 

109 AI was quite good using Vertical maneuvers and cloud cover.  Myself, using a combo of vertical and turn maneuvers to evade and change the battle from defensive/evasive to offensive.  I just have to watch my ammo usage.

It was a fun mission.

[Venturi]

I do find the Yak-7 to be a classy and easy to fly aircraft.

 

In many ways it’s the best Allied fighter to date, and has the best chance against a well-flown 109 or 190.  

[BlitzPig_EL]

1 hour ago, Venturi said:

I do find the Yak-7 to be a classy and easy to fly aircraft.

 

In many ways it’s the best Allied fighter to date, and has the best chance against a well-flown 109 or 190.  

 

Totally agree.

[blitze]

8 hours ago, Venturi said:

I do find the Yak-7 to be a classy and easy to fly aircraft.

 

In many ways it’s the best Allied fighter to date, and has the best chance against a well-flown 109 or 190.  

Oh I don't know, the easiest to fight them with engine management (temp / rad management) aside but the P39L and La-5fn also provide the Luftwaffe with a challenge.  More a case of the combination being the VVS on a par with the Luftwaffe fighters and any of those fighters, VVS/Luftwaffe in good hands can be capable.  I can see how the VVS getting into its stride with experience, tactics and equipment, they were able to turn the tables on the Luftwaffe mid war.

 

One has to remember that the Luftwaffe entered the war with a huge advantage in all of those due to their testing in Spain and then further experience gained in Western Europe.  That Western Europe folded so easily to the German tactics, it might have actually been a disadvantage to the Germans when it came time for their push East.  Stupid that they went to war in the East but that is history.

 

Much more learning for me to do on the Yak's with regards to management but they are good to fly.

[216th_Jordan]

13 hours ago, blitze said:

Found Water more important to monitor than Oil which could be set at less open setting.  Also watching throttle, rpm helped and speed as well.  Like the other Yaks, trim plays a big part in speed and energy fighting.

 

 

The impression might be wrong. Oil needs longer to heat up but also needs longer to cool down and the radiotor is not really sufficient. Its usually Oil that overheats (do a quick mission and check) water temp can go AFAIK to 115 °C but once oil hits the maximum you need to drastically lower the water temp which has the effect of additional cooling of the engine which will also cool down the oil because the oil radiator is unable to cool sufficiently at 100%.

[Tag777]

I am very happy with the Yak 7b. Last night on WoL It was a Kuban map and the engine started to overheat, but I open oil rad 100%, water 100% and diving and that cooled the engine relatively fast. Then I closed the water rad to 60-70% and maintain oil at 100%. The engine performed well and the temperature remained stable.

[dburne]

Hmm I might have to start another career in the Yak 7b just to give it a whirl.

Really enjoying my Spit career.

Before the Spit, I always flew a Yak - mainly the Series 169.

 

[Bilbo_Baggins]

It is quite strange how this airframe in-game rolls faster than the Yak 1. Does anyone know what's up with that?

Edited April 13, 2018 by Mcdaddy

[BlitzPig_EL]

Have you actually measured the roll rates?

 

What is the difference between them?

[spamRoast]

I just finished a career flying in the 6th GIAP with the 7b and 1b and I gotta say, I love these planes. I think I like the nimbleness of the 1b a little more, but the 7b is still an awesome plane and it's a close second for me. I like flying missions in either of them. I started this sim learning the German planes, but there's just something about the Yaks that I love.

 

On 4/13/2018 at 1:54 PM, Mcdaddy said:

It is quite strange how this airframe in-game rolls faster than the Yak 1. Does anyone know what's up with that?

 

Hmm. To me it seems like the 1b rolls faster than the 7b, but that's just my experience and I could be wrong.

Edited April 22, 2018 by obit

[Bilbo_Baggins]

On 4/14/2018 at 8:49 AM, BlitzPig_EL said:

Have you actually measured the roll rates?

 

What is the difference between them?

 

https://forum.il2sturmovik.com/topic/34462-test-roll-rate-fw-190a3-bf109f4-la5-lagg3/?page=2

 

Yes it's more responsive and slightly quicker through the roll at all speeds.

 

These examples here though are all at 800m, 400kmh. The 7b was 3.7 seconds compared with 4.5 seconds of the yak1, and it definitely feels that much quicker at higher speeds too.

Edited April 22, 2018 by Mcdaddy

[ShamrockOneFive]

On 4/13/2018 at 4:54 PM, Mcdaddy said:

It is quite strange how this airframe in-game rolls faster than the Yak 1. Does anyone know what's up with that?

 

It's notoriously difficult to dig up information on these kinds of things for Western aircraft nevermind Russian... but we have a few clues here from the dev notes.

 

Quote

Although from the famous Yak family of fighters, the Yak-1b (series 127) required almost a complete overhaul of the existing Yak-1 (series 69) 3D model. From the development point of view this is almost a completely new aircraft. There are several subtle differences that influence its physics model – a different propeller, automatic tail wheel lock similar to the MiG-3, simplified trimmers (just bendable fins instead of separate trimmer surfaces), improved seals for openings, additional engine exhaust covers, a different engine intake, and, of course, a lowered fuselage spine with a teardrop canopy. All of these changes led to better aerodynamics and performance than previous Yak models. The Yak-1b also had more armor in the front section of the fuselage and it had a different armament package. Armament consisted of a 20 mm ShVAK with 140 rounds and a 12.7mm UBS machinegun with 220 rounds. Designers also removed the underwing rocket rails.

 

The Yak-1B is the plane being discussed and the roll rate improvements aren't specifically mentioned but I would assume (such as we can) that the Yak-1B Series 127 or a series update somewhere along the line had some sort of improvement or a series of improvements to the ailerons that improved the roll rate. The Yak-7B Series 36 is a parallel development but I would guess also received similar updates. The Yak-1B Series 127 and Yak-7B Series 36 were produced about the same time - in the Spring of 1943.

 

So a lot of features are going to be either shared or developed in parallel and that would mean that its not too surprising that the Yak-7B's handling and overall performance is similar to the Yak-1B Series 127 than the earlier Yak-1 Series 69.

 

I'd be completely fascinated with a future addition of an earlier Yak-1 or Yak-7 version. There were a ton of changes from the earlier models and I'm always interested in seeing the progression (from Bf109E-7 to Bf109G-6 for example!).

[Bilbo_Baggins]

2 hours ago, ShamrockOneFive said:

 

So a lot of features are going to be either shared or developed in parallel and that would mean that its not too surprising that the Yak-7B's handling and overall performance is similar to the Yak-1B Series 127 than the earlier Yak-1 Series 69.

 

 

Great post. Enjoyed reading the dev diary excerpts again. 

 

Yak 1b and series 69 aileron performance is essentially the same, as to be expected. There was also negligible difference in the roll times when I recorded those tracks for the video. It's the 7b that behaves a lot differently (3.7 seconds vs 4.5 for the Yak 1), yet with the same wingspan and same aileron dimensions, hence the curiosity.

Edited April 23, 2018 by Mcdaddy

[ShamrockOneFive]

1 hour ago, Mcdaddy said:

 

Great post. Enjoyed reading the dev diary excerpts again. 

 

Yak 1b and series 69 aileron performance is essentially the same, as to be expected. There was also negligible difference in the roll times when I recorded those tracks for the video. It's the 7b that behaves a lot differently, yet with the same wingspan and same aileron dimensions, hence the curiosity.

 

It's really fun to go back and see stuff that we now take for granted and have the excitement all over again

 

My impression, flawed as it may be, was that the Yak-1B Series 127 rolled better. But maybe it doesn't.

[Dakpilot]

Yak 7 had quire different wings and aileron set up from Yak 1, same shape as later Yak 9 which was better aircraft generally than Yak 1,  whether this results in different roll rates I cannot say but I would expect a difference in handling as is mentioned historically, this should not be surprising or strange. 

(there was speculation on whether the Yak 1b was a Yak 9 when first sneak pics were released, wing plan form shape confirmed Yak 1b)

 

Cheers, Dakpilot 

 

[Stryker07]

So I experienced my first gun jam in BoX in the Yak-7 yesterday. While getting my guns on a 109 I fired a burst and bunted the nose down at the same time. Besides missing by a wide margin, I got a message that said gun out of ammo. I go to fire the MGs again and only one fired. I wasn't hit, no AA or enemy aircraft in any position to shoot me, it was a genuine jam. This is the first, and so far only, time I have had a jam in BoX.

[CrazyDuck]

33 minutes ago, Stryker07 said:

So I experienced my first gun jam in BoX in the Yak-7 yesterday. While getting my guns on a 109 I fired a burst and bunted the nose down at the same time. Besides missing by a wide margin, I got a message that said gun out of ammo. I go to fire the MGs again and only one fired. I wasn't hit, no AA or enemy aircraft in any position to shoot me, it was a genuine jam. This is the first, and so far only, time I have had a jam in BoX.

 

Are you sure the gun wasn't simply empty? Don't forget that one machinegun on Yak-7B carries 260 rounds, while the other one has only 140.

[-TBC-AeroAce]

I have has some strange stuff happening on mp recently like if you change airbases and you do not go back into setup and re-select your load out it will spawn as default or with no ammo.

[No_85_Gramps]

I've had this "no ammo" glitch show up a few times in MP.

[Stryker07]

1 hour ago, CrazyDuck said:

 

Are you sure the gun wasn't simply empty? Don't forget that one machinegun on Yak-7B carries 260 rounds, while the other one has only 140.

 

Ahhh, I bet that's what it was then. 

[216th_Jordan]

13 hours ago, Mcdaddy said:

 

Great post. Enjoyed reading the dev diary excerpts again. 

 

Yak 1b and series 69 aileron performance is essentially the same, as to be expected. There was also negligible difference in the roll times when I recorded those tracks for the video. It's the 7b that behaves a lot differently (3.7 seconds vs 4.5 for the Yak 1), yet with the same wingspan and same aileron dimensions, hence the curiosity.

 

Yak-9 was known to be a very good roller, as it shares the same wings as the Yak-7 I'd expect them to behave equally. I don't know how the wings compare in particular though, would be interesting to know.

[spamRoast]

14 hours ago, ShamrockOneFive said:

My impression, flawed as it may be, was that the Yak-1B Series 127 rolled better. But maybe it doesn't.

 

I assumed the same, but I know very little about their differences aside from how they feel when I fly them and I'm no expert in plane characteristics or history (beginning to love learning about them though).

 

Anyway, someone else used the word "nimble" to describe the 1b and it's exactly the word I was thinking of during my first post. Something about the 1b just feels nimbler to me and I assumed that included the roll rate, but I guess I'm wrong. Maybe the nimble feeling is just that the 1b is lighter. Whatever difference I noticed in nimbleness, whether real or imagined, was a very small difference though and I love em both.

Edited April 23, 2018 by obit

[Caudron431]

2 hours ago, 216th_Jordan said:

 

Yak-9 was known to be a very good roller, as it shares the same wings as the Yak-7 I'd expect them to behave equally. I don't know how the wings compare in particular though, would be interesting to know.

In fact the Yak9 had a new wing, very different than those of the previous Yaks. (Those wings are IMHO among the most beautiful ones built during WW2). They were more rigid as they were made with duralumin spars and maybe this gave an advantage too.

 

" The -9 featured the new and revised tip arrangement on wings of 9.74 meter span. The result, in planform, is a rather 'blunted' shape, but one that is pleasing to the eye. " extract from:

 

http://vvs.hobbyvista.com/Research/Yakovlev/FuelGauges/

[ATA_Vasilij]

Just dont want to be this topic forgotten, when I want to shout a Glory to this plane!

I wanted to say: This plane is a beast! - Best plane which VVS now has. Just superior in maneuvers and firing damage.,... Love it!

[=621=Samikatz]

On 4/23/2018 at 7:00 PM, Caudron431Micha said:

In fact the Yak9 had a new wing, very different than those of the previous Yaks. (Those wings are IMHO among the most beautiful ones built during WW2). They were more rigid as they were made with duralumin spars and maybe this gave an advantage too.

 

" The -9 featured the new and revised tip arrangement on wings of 9.74 meter span. The result, in planform, is a rather 'blunted' shape, but one that is pleasing to the eye. " extract from:

 

http://vvs.hobbyvista.com/Research/Yakovlev/FuelGauges/

 

What this article misses is that the Yak-7B had a different wing to the Yak-7A

[spamRoast]

7 hours ago, 3.IAP_Vasilij said:

Just dont want to be this topic forgotten, when I want to shout a Glory to this plane!

I wanted to say: This plane is a beast! - Best plane which VVS now has. Just superior in maneuvers and firing damage.,... Love it!

 

Have you tried the 1b? If you like the maneuverability of the 7 you'll probably like the 1b a lot too. It's lighter and has an edge on maneuverability I think. And the bubble canopy is great. It's got a lot less of the 12.7mm rounds though so you really have to conserve ammo, but even with that, I still think I prefer it over the 7. Not to say the 7's not an awesome plane too though. I know this is a thread on the 7. I'll go find a 1b thread now lol.

I'm new to the Yaks but love em all so far. I really hope we can see some 3's or 9's in this series some day!

Edited May 22, 2018 by obit