Why do people think the 262 accelerates poor?

[niklas]

Originally posted by Zigrat:
swept back wings have inherently lower lift curve slopes and lower clmaxs until u get into the range of leading edge extentions and severe delta effects

Now guess why the 262 had leading edge slats over the full wingspan  

niklas

[chunder']

Was not aware of that... alas, my touchy-feely experience is limited to formerly fixing B-52H's and now working this hydraulic sprinkler they call the B-1B.

PS, thanks for the young pup, most of the guys I work with call me an old fart.  

[ 08-12-2001: Message edited by: chunder ]

[AKHog]

Originally posted by niklas:

Of course i can compare acceleration with climb rates. They´re close together. A plane that outclimbs an other plane at a certain speed will outaccelerate it at this speeed in a horizontal flight

HAHAHAHA!

Guess again.

[ 08-12-2001: Message edited by: AKHog ]

[BenDover]

Originally posted by niklas:

P.S
Will we get this armment option?
  (Image removed from quote.)

wtf is that!!!   Is it a 40mm cannon or something??  

[Staga]

BK-5 50mm

[Zigrat]

i dont know why you laugh at his statement akhog, it is correct.

tho his statement that the me262 accelerates "well" has holes, since it accelerates like a dog at low speeds, it does indeed accelerate well, compared to propeller driven aircraft, at high speeds.

[AKHog]

I was not laughing at his statement about the 262, i know very little about it. but where he says accel and climb rate are basicaly directly related made me laugh.

Given that in AH we see the best climbing planes also have good accel the 2 actualy have nothing to do with eachother.

One is a function of thrust vs wiegh and the Co of lift at a speed, the other is a result of total mass and has a lot to do with areodynamics, rather then just pure power.

If your intrested look up the actual equations, you'll see they have very little to do with eachother.

[AKHog]

OK thinking about it more.

I guess if you look at this in the most basic way then accel can relate to climb rate. but this is looking at it and disregarding areodynamics. like a model rocket, if you make if heavier or take away power you can hurt its accel AND climb performance. Without going to deep into things just look at the areo equations for climb and accel and i think you'll know what i'm talking about.
I'll try to find em and post a link to em here.

[Jigster]

I wonder if we're going to get those wonderful flame outs and fire warnings this time around? Kinda dumb to include yet another Jumo powered plane without it's most historically significant feature.

Heck, there's not even an exhaust nozzle temp gauge to contstantly eyeball in the 234.

Well come to think of it, the pony starter engine in the intake cone was probably the most significant, then the the fire related stuff  

[hitech]

AKHog Climb rate and accelertaion are almost the exact same mesurment. But both have to include an (at what speed term). The only areodynamic part that makes them different is the decrease in lift needed (hence less drag) in a climb VS 1'g of lift needed in level flight where Accel is messured.

Basicly both are a direct computation of excess power (total thrust - total drag) * speed. That excess in power can either be used to climb or accelerate, both climb and accel are function purly of the mass and excess power.

I think the reputation of the 262 for crapy acceleration comes mostly from is take off performance. In the slow speed realm props generate much more thrust than the jets.

HiTech

[F4UDOA]

HiTech,

I disagree about climb/Acceleration being so closely linked. I know that they are both a measure of excess power however there are many other variables.

1. The wing ultimately determines the climing ability of an A/C. A high lift wing (Aspect ratio) will give an A/C excellent climb with relatively low power and yet poor acceleration.

2. An A/C such as the GeeBee racer with an extremely low Aspect ratio and very good power to weight would have excellent acceleration and (relatively) poor sustained climbing ability.

I know that WW2 fighters where somewhere in between these two design concepts but the basic idea for good acceleration is the same, power/weight + low drag, from the GeeBee to the F-15. Not to mention other variables such as cowl flaps being open for cooling during climb which would slow climb rate but not affect an A/C in level acceleration.

All in all I have never accepted the climb/acceleration relationship in AH.

[flakbait]

Some trivial figures:

Jumo 004B thrust: 1,980 lbs

Me-262-a1
Twin Jumo 004B engines
Total thrust: 3,960 lbs
Typical weight: 14,101 lbs
Thrust to weight ratio: 0.28:1

Ar-234B
Twin Jumo 004B engines
Total thrust: 3,960 lbs
Typical weight: 18,540 lbs
Thrust to weight ratio: 0.213:1

F-16  
Single P&W turbofan
Total thrust: 29,100 lbs
Typical weight: 28,000 lbs
Thrust to weight ratio: 1.04:1

-----------------------
Flakbait [Delta6]
Delta Six's Flight School
Put the P-61B in Aces High
"For yay did the sky darken, and split open and spew forth fire, and
through the smoke rode the Four Wurgers of the Apocalypse.
And on their canopies was tattooed the number of the Beast, and the
number was 190." Jedi, Verse Five, Capter Two, The Book of Dweeb
 

[funkedup]

Wells and HT are absolutely 100% correct guys.

[AKHog]

Thanks HiTech. I looked at some areo eng books last night that an old friend let me borrow. Although I couldnt find the exact equations, they do seem pretty closely related from what I did find. The exact opposite from what I remeber. I stand corrected, admit to my mistake, please dont ban me  .

F4UDOA: I think they are talking more about accel at a given speed vs climb rate at that same speed. You point is good and valid but if you speed the geebee up to it's max climb speed it'll have relatively equal accel from or around that speed compared to other planes.

[AKHog]

Flakbait: Can you find T/W on a 109 g-10??

That would be intresting. Assuming all the numbers posted by people here are close to true, and seeing how the 262's T/W is .28/1, I would guess the 109 is much closer to .5/1 if not higher, yet the 262 would have a better climb rate of 4000ft/min at ~320 ish kph.
I wonder what the 262's accel from around 300 to 350 kph is. If they [accel and climb rate] ARE closely related then the 262's 300-350 performance should be better then the 109 g-10's 150-200 accel rate.

Just a thought  .