Spitfire XIV vs Bf-109 K-4 vs La-7 vs Yak-3

[Juha]

A would like to ask a question.
La 7 weas faster at SL than K-4 1,8. According to Corsing s datas 11mph , according to Juha s wishes 29mph
1) Both aircrafts HAVE 1850 HP
2) la 7 has very good cowling surface but a RADIAL engine while K-4 an in line engine.
3) La7 has a bubble canopy , which is useful but druggier than the classic canopy of the K-4
4)La 7 has a wing surface of 17,59 m2 vs 16,05m2 of the K-4
5) Both aircrafts have fuselages of similar size, fully covered landing gear , and generally are well streamlined
6) La 7 has 3 20mm gun ports on the nose. K4 has two 13mm openings
7) All russian fighters use rather outmoded wing profiles( i think so,if wrong correct me)

The question is: Where the speed advantage of La 7 comes from? the difernce, according to juha , is almost 50Km/h!!!
propellers efficiencies deont explain anything. K4 had a brand new desigh and even if La 7 s was even better the 29mph gap is huge to be explaned by propellers efficiencies alone
And the phenomenon gets even better. K4 ,even with 2000ps, is still much slower. Even if careful construction is achieved ,and K4 gets the 12 kph bonus reported in Kurfusts site, still is far behind La 7
Even the better supercharger of K4 , which provides better power curve ,fails to provide k4 with a speed anywhere near the La 7 before the medium altitudes area.
Any logical explanation?
PS Even the allien P51 in order to achieve speeds similar to la 7s needs laminar flow wing, very advanced cooling system design, exceptional construction quality, super-duper fuels and sometimes sanding.

Hello Jim
Lets see
La-7 max speed at SL 612km/h in 1944 and 613km/h in 1945 according to Yefim Gordon and 592km/h according to Milos Vestsík.
The canopy of La-7 wasn't a pure bubble but more a half-way solution between bubble and highback
Most of La-7s had only 2 20mm ShVAK cannon only few had 3 B-20s

Juha

 

[Aozora]

Juha,
God bless you. I've already started to do a work up on the DB and DC engined K-4 and will post as soon as I can but right now work tomorrow is calling me so I have to go to bed. God bless you all and have a good night. I'll see what I can do about terrorizing you all tomorrow. And by the way Juha you are probably right, its just that German junk throws me off, from time to time.

This might be of some interest to you:

 

[CORSNING]

Thanks Aozora, I haven't had the time to read it yet but it looks great, thanks again.

tomo try this sight: www.btinternet.com/~fulltilt/Perform.html

jim, I'll probably be puting foot in my mouth but when looking at the climb rate graphs it appears that full power for the K-4 kick in from 550-750 meters. At 750 meters the K-4 with the 605D engine is going 392 mph.

 

[tomo pauk]

Bad link

 

[CORSNING]

Sorry tomo, I'll try again tomorrow. Hey man, try to go to Google and punch it in.
Best of luck, Jeff.

 

[tomo pauk]

Works

 

[alejandro_]

The question is: Where the speed advantage of La 7 comes from? the difernce, according to juha , is almost 50Km/h!!!

If you are referring to the model that reached 640km/h, it's an experimental model. It was not built in large quantities. Bf 109 K-4 top speed at sea level is ~365mph, 588km/h.

5) Both aircrafts have fuselages of similar size, fully covered landing gear , and generally are well streamlined

At this stage of the war I would expect La-7 to be better finished that K-4. Soviet designers had time and resources to improve aerodynamics and manufacturing of La-7. The Germans couldn't afford this. K-4 is an attempt to standarise Bf 109 production.

6) La 7 has 3 20mm gun ports on the nose. K4 has two 13mm openings

As others have said, most La-7 had 2 ShVAK guns.

propellers efficiencies deont explain anything. K4 had a brand new desigh and even if La 7 s was even better the 29mph gap is huge to be explaned by propellers efficiencies alone

La-7 had a new propeller. It would be interesting to see an engine power graph for both models. The supercharger critical altitude could be different in both models.

 

[tomo pauk]

...

La-7 had a new propeller. It would be interesting to see an engine power graph for both models. The supercharger critical altitude could be different in both models.

In really low altitudes, the DB-605 has between 100-150 HP more, DB using MW-50 and C3, ASh using 'forsage' (dashed red line, 10 min setting).

 

[CORSNING]

Nice graph tomo.
The La-7 performance when first introduced to squadrons was a disappointment. They loved the plane but the specs were lower than they were lead to believe. A cleanup of design ensued with many cowling and fuselage gaps being sealed in production around October 1944.

The following performance figures are from the graphs at Kurfurst for the Bf 109K-4:

Altitude (m).DB605DB/ASB...DB605DC/ASC
..................B4 and MW50....C3 NO MW
......0..........369/4360..........365/4260
1000...........383/4365..........378/4250
2000...........396/4202..........392/4095
3000...........404/4044..........401/3925
4000...........413/3890..........410/3760
5000...........422/3680..........420/3590
6000...........431/3552..........423/3425
7000...........441/3129..........438/2940
8000...........436/2480..........437/2430
9000...........430/1968..........430/1930
10000.........421/1485..........420/1435
11000.........407/ 964...........407/ 925
12000.........388/ 462...........390/ 425

As before, speeds: Not sure if actual test or calculations. Climbs I believe were calculated.

NOTE: I have read in several places that the K-4 had a few different versions of the 605 engine installed in production A/C. I do not know exactly what versions were actually used in combat.

alejandro is correct about most La-7s having only 2x20mm armament. The three gun (B-20) model did not appear until 1945.

 

[Vincenzo]

Works

it not work for me also today

 

[tomo pauk]

Think I have the answer for jim's question:

7) All russian fighters use rather outmoded wing profiles( i think so,if wrong correct me)

The La-5/7 were featuring the NACA 230 series wing profile, ie. same as Fw-190 and Bearcat, for example. The Bf-109 was the one with outdated profile.

Looking at CORSRING's posts, the K-4 was not using both C3 and MW-50 in the same time, so the 'base' power was 1800-1850 HP, not the 2000 HP. So no power advantage vs. ASh-82 FN at really low altitudes.

Here you go, Vincenzo

 

[Vincenzo]

ty tomo at first are around the same of George

 

[CORSNING]

Very nice tomo. I have not learned how to copy from one sight post on another.

 

[tomo pauk]

how to copy from one sight post on another.

I'm not getting that

added: I've got the graphs for the La7, (here), even while the speed measured is IAS, the top speed at SL is under 600 km/h, on 'augmented power', or 'forsage'.
Unfortunately, the author states engine as 'two stage'.

 

[Vincenzo]

Corsning you writed that Graph give 389 mph SL but as i can read it's more a 359 mph
what's wrong?

 

[CORSNING]

Vincenzo and tomo,
I am not leaving you guys, I took my wife out to party tonight, and am unable to respond at this time in a gentlemanly manner. I have to DJ at her place of establishment in the morning (she is a bar tender). But if I have the mental capacity after that (I will be asking God's help by the way) I will get back with you and try to sort this all out.

jim,
Where do you live. So that in the future I can be more considerate of your time zone?

 

[GregP]

I'd like to throw in something here. The Bf / Me 109 was pretty outdated by the time of the K-4. It was a superlative digfighter at 180 - 290 mph, but was losing a lot when faster than 320 mph. At 400+ mph, it wasn't fighting at all ... it was running TO a fight or FROM a fight, but was definitely not maneuvering IN a fight. It was barely controllable at 450 mph and the pilot was almost unable to change directions at that speed.

The same cannot be said for some of the competition.

I really like the 109, but a fast dogfighter it wasn't.

 

[CORSNING]

The graph I used is from this sight. You have to go to the TECHNICAL section and look under FLIGHT TEST DATA. Bottom of the first page is asking for Russian A/C data. I looked at the graph again and it looks like the sea level speed is 615/617 at a glance. I cant remember where the 389 came from so I'll have to look at my files closer when I get back home today.

tomo, I have not learned how to post another sight like you did the La-7 information. I have to type it out letter by letter.

 

[Tante Ju]

I'd like to throw in something here. The Bf / Me 109 was pretty outdated by the time of the K-4. It was a superlative digfighter at 180 - 290 mph, but was losing a lot when faster than 320 mph. At 400+ mph, it wasn't fighting at all ... it was running TO a fight or FROM a fight, but was definitely not maneuvering IN a fight. It was barely controllable at 450 mph and the pilot was almost unable to change directions at that speed.

The same cannot be said for some of the competition.

I really like the 109, but a fast dogfighter it wasn't.

Bf 109F recovering and leveling out from near vertical dive at 520 mph within 4000 feet in appx. 4 seconds. Bf 109K was redlined at 527 mph and had lightened elevator forces.

 

[tomo pauk]

Oookay, CORSRING, by 'sight' you mean 'site', web site? If the document is in the PDF format, download it on your PC, than upload it here, via 'Manage attachments' button when replying on 'Advanced' mode. In case the web site is no longer hosted at original place, one can use 'Wayback machine' to get some of the contents of the 'former' web site.

If you don't want to type out stuff, nor you want to upload the whole document, you can use screen grab, usually activated by clicking on the button resembling to the old photo-aparatus. Select the area of the page, or whole page, and, usually after you un-click the mouse, the selected area is copied into clipboard. Then fire up the MS Paint ( usually installed with Windows), paste the clipboar content, edit the picture if needed (borders mostly, size sometimes), save as JPG.
For screen capture you can use 'prt sc', or print screen button on your keyboard, the screen is copied into clipboard that way, too.

Unfortunately, some stuff is usually lost forever, so I have a habit to download a whole web page sometimes, then to take my time to extract the 'good' stuff. Ie. first shoot, ask questions later