Why do people think the 262 accelerates poor?

[niklas]

ok on the runway the 262 has poor acceleration, but once airborn only few aircrafts can catch it in a climb.

It climbs with ~4000ft/min at sealevel with full internal fuel tanks, only few propeller driven aircrafts were better. And the Me262 could climb with 4000ft/min @340mph, which is for most propeller driven aircrafts close to topspeed (or higher). That means it could easily outclimb near sealevel an enemy at this speed.
Of course climbrate drops fast with altitude, but acceleration near sealevel was not so bad!

niklas
P.S
Will we get this armment option?
 

[Westy MOL]

ALL the WWII jet engines revved up very slowly. The Meteor, ME-262, P-80 could only accelerate well if you put several sticks of TNT up thier pipe  

 Don't confuse acceleration with cruise speed, maximum speed, dive or climb rates. Once these planes were up to speed THEN yes, not much could touch them at all. It just took quite a long distance to do that.

 Westy

[niklas]

Don't confuse acceleration with cruise speed, maximum speed, dive or climb rates.  

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

niklas

[ra]

From a standing start every fighter in AH can get to 300 mph faster than the Me-262, and every fighter can get to 10K faster than the 262.  Once the 262 gets to 300 mph or to 10K, everything changes.

ra

[Staga]

262 did climb nicely after its turbines got enough rpm.

[juzz]

But how well does it climb/accelerate at speeds under say, 300mph? That's when the prop fighters will murder it - but in high speed acceleration the Me 262 will be far superior.

[niklas]

Originally posted by Staga:
262 did climb nicely after its turbines got enough rpm.

But later, in a flight, the rpm was almost constant. There was an automatic regulator to keep rpm constant.Thrust was regulated by the "jet-needle" at the end of the turbine (it changes the area for the massflow: less area faster speed of the exhaust gases = more thrust).
Of course the pilot could choose lower rpm settings, but even for economic flight, rpm setting was 8000 compared to 8700 (maximum).
The major problem was to get the engine from 0 to 8000+ for takeoff

btw ra, altitude is not good for a jet like the me262. The 262 performs best near sealevel compared to prop driven fighter, where the engines produce the most thrust.

niklas

[ 08-11-2001: Message edited by: niklas ]

[Toad]

Spool time.

[Nashwan]

The poor climb and acceleration at low speeds is partly caused by the engine taking time to spin up, but also due to the low thrust from the engines, even when at full rpm. Jets will produce more thrust as speed increase, though not by much. Props produce far more thrust at low speed than at high speed. At lower speeds a typical WW2 fighter will have better thrust/weight ratio than the 262.

[ 08-11-2001: Message edited by: Nashwan ]

[ra]

niklas,

Altitude reduces the maximum thrust of the engines but gives the pilot the ability to dive away from any attacker.  I was trying to point out that only when a 262 reaches about 10K does it's performance make it nearly invulnerable to attack.  A low 262 even at maximum level speed can still be caught by a diving fighter.

ra

[funkedup]

Niklas figure out thrust to weight ratio at sea level and 150 mph for Me 262 and Me 109.  Then you will see what people are talking about.    

It's got nothing to do with spool time or altitude.  It's got everything to do with the fact that props have maximum thrust at low airspeeds, while jets have roughly constant thrust regardless of airspeed.

Acceleration of the 262 at high speeds was unmatched by prop planes.  But at low speeds it was a dog.

[ 08-11-2001: Message edited by: funkedup ]

[Zigrat]

what funky said

the jet produces relatively similar thrust across a range of airspeeds

the prop, while having lower efficiency at low airspeeds has much much higher thrust

for example, at stall speed a 109 g10 is producing a helluva lotta thrust   it can just from 100 to 200 mph real quick like

the me262 has comparaticvely low thrust in this case


plus the me262s wing's sweepback is a big disadvantage from a turning standpoint. 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

[Toad]

Yeah, funk?

You ever have a student flare high and whip the throttles to idle in a turbojet KC-135R?

14 seconds idle to max.

Did I mention 14 seconds can be a lifetime?  

Spool time.

... in some cases.  

[chunder']

But the 135 R model doesn't have turbojets, it has turbofans  

<G,D,R>

[Toad]

Chunder, my son.. back in the mists of time there was a KC-135R. In those olden times, the "R" stood for Reconnaissance.

<EDIT>

 http://www.aerospaceweb.org/aircraft/transport-m/c135/index.shtml

Here ya go, ya young pup. Check out this webpage:

"KC-135R  Originally designation for KC-135A airframes modified for special reconnaissance duties; 4 converted  


There was just one left of the four when I got to the squadron. We used it on the Cuban missions because the "package" was less capable than the RC-135C/M/V/U which had TF-33's. Cuba did not require the latest technology.

We also used it for the "pilot trainer" because the equipment wasn't so sensitive to the bump and thump of touch and goes.

I know I have the ship number in my logbook somewhere.

You are correct about the Johnny-come-lately KC-135R's though. Usurpers of a proud name, they are 'fans.

I'm going back to the rocking chair now.    


(mumble, mumble  "young pups")  

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