Author Topic: La7 speed at 13k is 10mph too fast (Read 1490 times)

thrila · « **on:** March 03, 2002, 09:35:04 PM »

Flew a la7 at 13k and it reached 400mph @13k with 50% fuel (no WEP). I thought this was a tad faster than it oughta be so i checked the charts- apparently it should only be doing about 390mph. Shave a few mph off the la7 plse HT cause i hate 'em:p

P.S. perk the la7:D

Raubvogel · « **Reply #1 on:** March 03, 2002, 09:48:49 PM »

Hey thrila...nice cat and mouse in those 262s...was fun.

Vermillion · « **Reply #2 on:** March 04, 2002, 06:52:06 AM »

Thrila, all posted speeds are for 100% internal fuel. Test it that way and check your results.

thrila · « **Reply #3 on:** March 04, 2002, 08:58:18 AM »

Awww you gotta be kidding me verm........ahwell back to the drawing board for me.

Raub, that was the most fun i've had in ages dogfighting in the 262 with you. I didn't even see you on my 6 until about 1.5k and i crapped myself hehehe. Luckily i got you to overshoot after your first pass and i thought you would be my first 262 kill in a 262.

I only had about 40 rounds of 30mm left so i was waiting for the perfect shot. Fortunately for you, you weren't staying still or slow for very long and doing some nice evasives. I thought i was gonna die when you dragged me to the depot but the ack wasn't up hehe- i was soooo lucky.

You then dragged me to that furball and a p51 tried to get on my 6 but i was too fast for him. I was low on fuel so i had to rtb and home i went hoping my fuel would last out. About 12 miles out my engines died so i had to glide the rest, i got there with a bit of speed so it wasn't too bad. Aaaarrgh!!! i bled to much speed when circling and touchedown short of the runway, luckily for me i rolled just onto the tarmac and landed perfectly......well almost.

Musta been my lucky day yesterday.

~~Raub, some nice flying yesterday i had lots of fun.~~

MANDOBLE · « **Reply #4 on:** March 04, 2002, 09:30:13 AM »

Verm, does more fuel imply more drag or less Hp?? AFAIK, more weight imply less acceleration in level flight, but same top level speed. If top speed is depending on internal fuel load, then there is something I cant understand in AH.

R4M · « **Reply #5 on:** March 04, 2002, 09:33:28 AM »

Quote

Originally posted by MANDOBLE
Verm, does more fuel imply more drag or less Hp?? AFAIK, more weight imply less acceleration in level flight, but same top level speed. If top speed is depending on internal fuel load, then there is something I cant understand in AH.

dont whine, is just a 4% difference so it is okay.

(aproximate answer I got in this same forum when I posted info and charts on the Fw190A5 being 10mph slower than what it should at Sea Level. It was never corrected, btw.)

Hooligan · « **Reply #6 on:** March 04, 2002, 09:36:02 AM »

Mandoble:

More fuel will cause more drag.

Hooligan

MANDOBLE · « **Reply #7 on:** March 04, 2002, 09:36:45 AM »

RAM, 4% is not ok, but a brutal difference when we are talking about plane types whose top speeds differences are between 5% and 10%.

Hooligan, are u able to explain why?

R4M · « **Reply #8 on:** March 04, 2002, 09:49:50 AM »

Quote

Originally posted by MANDOBLE
RAM, 4% is not ok, but a brutal difference when we are talking about plane types whose top speeds differences are between 5% and 10%.

Mandoble, I know. I was being sarcastic about the matter. As I said, I once came with some focke-wulf factory charts about 190A5's SL speed some time ago, being it around 345-348mph@SL in the chart while at AH its 335mph@SL.

Answers to an official focke-wulf chart showing AH's 190A5 being 10mph too low met several answers saying that "it isjust a 4% difference in the topspeed, so it is ok"

So I hope you understand the big ammount of sarcasm involved in my previous post in this thread.

Quote

Hooligan, are u able to explain why?

More weight needs more lift from the wing to compensate. More lift provided by the wing means more drag. More drag means reduced top speed.

However a 50%-100% fuel weight difference shouldn't cause a 10mph speed difference. Its too big a difference.

MiloMorai · « **Reply #9 on:** March 04, 2002, 10:01:17 AM »

Give your ground crew a case of vodka for polishing, taking out any imperfections , super tuning the engine,........ your a/c.

MANDOBLE · « **Reply #10 on:** March 04, 2002, 10:05:31 AM »

that kind of drag at these speeds should affect minimaly top speed. U are well above stall speed, in fact u need to be trimmed nose down to dont start gaining alt. At these speeds you are not fighting against your weight, just the contrary, you are fighting against your lift to keep level flight.

thrila · « **Reply #11 on:** March 04, 2002, 10:21:54 AM »

Ok, i went and tested the la7 speed offline. Went to a 15k field took off and dove down to 13k and levelled out. Went and ate my lunch and when i got back 10mins later the la7's speed was 399mph (the 400mph white line was almost completely covered).

So in my view the la7 is too fast at 13k. Gonna try at different alts 15k, 17k, 20k later on and see what i get.

Vermillion · « **Reply #12 on:** March 04, 2002, 10:38:53 AM »

Mandoble, like Hooligan said total weight has an effect on top speed. Its not as much as you would think, but it does have an effect.

In this case I'm guessing probably about 3-5 mph.

Thrilla, no offense buddy, but if you can read those itty bitty analog gauges to a tolerance of 1 mph, you have eyes better than mine. From my experience, its hard to get an accurate reading within a plus or minus 5 mph tolerance.

straffo · « **Reply #13 on:** March 04, 2002, 10:45:58 AM »

use auto-trim for angle in conjonction with the .speed command...

exemple : you set auto-climb angle and next you type .speed 400

if it climb you are fastest than 400
if it dive you are lower than 400

and it's better than reading gauges ...
btw you would be better to set the fuelBurnrate (spelling?) (*) to 0

(*) it's an arena parameter.

MANDOBLE · « **Reply #14 on:** March 04, 2002, 11:03:53 AM »

Verm, I need a rational explanation of that.

At 15k, at your top speed, lift will be greater than weight, so, to compensate, you'll need to trim your nose down. If you are lighter, you will need to compensate even more, so your trim tabs, or entire elevators will generate more drag than if you were heavier (less overcompensation needed to keep level flight).

Basically, heavier or lighter you are tending to climb and we are talking about level top speed, not climb rate.

Where am I wrong?