Author Topic: What makes La-7 ~30-MPH faster than La-5FN at ALL Altitudes... (Read 4792 times)

1K3 · « **on:** February 01, 2007, 11:20:33 PM »

What makes La-7 ~30-MPH faster than La-5FN at ALL altitudes when both planes have the SAME engine AND power output...

Karnak · « **Reply #1 on:** February 01, 2007, 11:40:11 PM »

Cleaned up detailing, streamlining and wax.

Saxman · « **Reply #2 on:** February 02, 2007, 12:42:04 AM »

It's the go-faster stripes.

Ball · « **Reply #3 on:** February 02, 2007, 12:49:08 AM »

type-r badge.

Debonair · « **Reply #4 on:** February 02, 2007, 01:47:11 AM »

the "FN" adds a lot of drag & "7" is more aerodynamic then "5" to begin with...

Mustaine · « **Reply #5 on:** February 02, 2007, 02:08:49 AM »

the purple power bands

Charge · « **Reply #6 on:** February 02, 2007, 03:35:26 AM »

Maybe the 71 lbs weight difference?

Some data I stubled upon on Ubi forums suggest 385-394mph for LA-5FN and 408 for LA-7 at 20 000 ft.

So the aerodynamic refinements and update in materials did improve the performance but how much it actually did improve..?

-C+

pipz · « **Reply #7 on:** February 02, 2007, 07:20:55 AM »

Im at work so Im recaling this from memory.The La7 has a revised wing shape which I think was also made thinner.The air intake was moved from the top of the nose to the wing roots.The oil cooler was moved from under the nose to under the body towards the rear.I beleive they brought the weight down a bit.It may have been through the use of less wood and more metal in certain parts.Again this is from memory but more or less gives ya an idea of what they did to the modify the la5 to the la7.It was basicly weight reduction and aerodynamic refinements.

"A bandit at your six is better than no bandit at all"
Pipz

Masherbrum · « **Reply #8 on:** February 02, 2007, 08:36:13 AM »

Quote

Originally posted by Mustaine
the purple power bands

Widewing · « **Reply #9 on:** February 02, 2007, 12:21:13 PM »

I'm still trying to figure out how the La-7 accelerates and climbs so fast considering that it's fitted with a low activity propeller of relatively small diameter.....

I also find it interesting that some Soviet aces preferred the La-5FN to the La-7.

My regards,

Widewing

Krusty · « **Reply #10 on:** February 02, 2007, 12:36:14 PM »

Do we have any non-Soviet sources that tested this aircraft? Perhaps NACA or captured LW, or even British/US tests?

I've always thought that the same engine in almost the same plane shouldn't have such a huge performance leap. I always suspected propoganda got into the test data, but this is mere speculation on my part.

1K3 · « **Reply #11 on:** February 02, 2007, 01:13:38 PM »

Quote

Originally posted by Widewing

I also find it interesting that some Soviet aces preferred the La-5FN to the La-7.

Yeah, but I. Kozhedub would beg to differ.

pipz · « **Reply #12 on:** February 02, 2007, 02:13:05 PM »

Quote

Originally posted by Widewing
I'm still trying to figure out how the La-7 accelerates and climbs so fast considering that it's fitted with a low activity propeller of relatively small diameter.....

I also find it interesting that some Soviet aces preferred the La-5FN to the La-7.

My regards,

Widewing

Only thing I could find in what I have is that on the LA-7 they used a Mach Resistant Blade airfoil.Im "assuming" by the way they wrote it that the la5 didnt have the same blade.But they dont get into the hard data stuff that you like.

As far as why they prefered the LA-5FN over the 7.I wonder if it had to do with fit and finish.At least at first.From what ive read la-7s had production problems at first.It got very hot in the cockpit because of bad sealing,but then again so did the LA5.They say that performance wasnt much better for the 7 at 1st because of sloppy construction.After testing the initial production planes they went around and fixed all the production problems and the planes performance improved.I wonder if they preffered the la5 only because they were dissapointed in the LA7.What I mean is that by that time all the la5 faults prolly would have been worked out.Now with the 7 ya have a whole bunch of new faults that had to be worked out.Just a thought.

Pipz

F4UDOA · « **Reply #13 on:** February 02, 2007, 04:09:33 PM »

Krusty,

I used to have the German test of the La-5 on my website, I think I may have taken it down.

I will repost it or email it to you.

Sombra · « **Reply #14 on:** February 02, 2007, 06:35:35 PM »

Quote

Originally posted by Widewing

I also find it interesting that some Soviet aces preferred the La-5FN to the La-7.

It's not exactly the same case, but maybe La-5FN pilots also distrusted the new type:

http://en.wikipedia.org/wiki/Aleksandr_Ivanovich_Pokryshkin

Quote

Finally in 1944 he found an aircraft that he was willing to convert to, Lavochkin La-7. Unfortunately one of his close friends, Soviet 50-kill (31 personal and 19 group) ace Alexander Klubov was killed in a landing mishap while converting to the La-7. The crash was blamed on the malfunction of the plane's hydraulic system. Pokryshkin subsequently cancelled his regiment's conversion, and there are multiple reports that they instead began flying Bell P-63 Kingcobras.