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Why does the shuttle throttle on ascent?



 
 
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  #1  
Old January 8th 07, 06:53 AM posted to rec.aviation.piloting,sci.space.history,sci.space.shuttle
Morgans[_2_]
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Posts: 3,924
Default Why does the shuttle throttle on ascent?


"Dudley Henriques" wrote

I flew a D, as well as various other prop fighters as a civilian operator.
Never flew ours with external tanks. The airplane is stable on takeoff if
flown correctly and I wouldn't anticipate any specific issues with the
external tanks except the extended run. I believe the only caution on the
external tanks was for high speed buffet above 400 mph.
We had the fuselage tank removed and only flew the Mustang using the 2
mains at 92 gallons each.(90 usable)


I had always heard that the fuselage tank was the source of the instability,
with it being so far behind the CG, to give it a dangerously aft CG. Today,
in peacetime, I don't suppose they would ever dream of putting that much
weight that far back, but it was war.

Comments?
--
Jim in NC


  #2  
Old January 8th 07, 03:21 PM posted to rec.aviation.piloting,sci.space.history,sci.space.shuttle
Dudley Henriques
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Posts: 269
Default Why does the shuttle throttle on ascent?


"Morgans" wrote in message
...

"Dudley Henriques" wrote

I flew a D, as well as various other prop fighters as a civilian
operator. Never flew ours with external tanks. The airplane is stable on
takeoff if flown correctly and I wouldn't anticipate any specific issues
with the external tanks except the extended run. I believe the only
caution on the external tanks was for high speed buffet above 400 mph.
We had the fuselage tank removed and only flew the Mustang using the 2
mains at 92 gallons each.(90 usable)


I had always heard that the fuselage tank was the source of the
instability, with it being so far behind the CG, to give it a dangerously
aft CG. Today, in peacetime, I don't suppose they would ever dream of
putting that much weight that far back, but it was war.

Comments?
--
Jim in NC


The fuselage tank held 85 gals of fuel and did indeed bring the cg back
causing a real change in flight characteristics. It really screwed around
with the pitch moments. It could be handled, but the general word was for
pilots to take the bird out with fuel in the tank and go upstairs and do
some "getting used to it" flying.
The danger point where it actually became a cg issue began at about 25 gals.
The flight characteristics got worse with more fuel in the tank over that 25
gals. At 40 gals in the tank, anything involving maneuvering flight was a
toss up for pitch control.
Dudley Henriques


  #3  
Old January 9th 07, 12:10 AM posted to rec.aviation.piloting,sci.space.history,sci.space.shuttle
Scott Hedrick
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Posts: 3
Default Why does the shuttle throttle on ascent?


"Dudley Henriques" wrote in message
...
At 40 gals in the tank, anything involving maneuvering flight was a toss up
for pitch control.


"This is your wingman. You appear to be leaking oil."
"Negative, wingman. The CG just shifted and I **** my pants."


  #4  
Old January 8th 07, 07:34 PM posted to rec.aviation.piloting,sci.space.history,sci.space.shuttle
Pat Flannery
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Posts: 72
Default Why does the shuttle throttle on ascent?



Morgans wrote:
I had always heard that the fuselage tank was the source of the instability,
with it being so far behind the CG, to give it a dangerously aft CG. Today,
in peacetime, I don't suppose they would ever dream of putting that much
weight that far back, but it was war.

Comments?

I'll take that any day of the week over the Bf-109, where you're main
fuselage tank goes under the pilot's seat, or the Me-163 where you're
sitting squeezed in between two tanks of hydrogen peroxide at your sides.
Another "brilliant" move was on the Sukhoi Su-7, where a cylindrical
fuselage fuel tank has a tunnel down its inside in which the jet engine
rests, so that bullets of shrapnel piercing the rear fuselage will
penetrate the fuel tank...and then the engine...letting superheated air
enter the fuel tank.
This led to some wonderful combat shots in the 1973 Yom Kippur war and
the wars between India and Pakistan of Su-7s plunging earthwards with
everything behind the wings ablaze and spraying fire all over the place
like a flamethrower.

Pat
  #5  
Old January 11th 07, 02:04 PM posted to rec.aviation.piloting,sci.space.history,sci.space.shuttle
MichaelJP
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Posts: 8
Default Why does the shuttle throttle on ascent?


"Pat Flannery" wrote in message
...


Morgans wrote:
I had always heard that the fuselage tank was the source of the
instability, with it being so far behind the CG, to give it a dangerously
aft CG. Today, in peacetime, I don't suppose they would ever dream of
putting that much weight that far back, but it was war.

Comments?

I'll take that any day of the week over the Bf-109, where you're main
fuselage tank goes under the pilot's seat, or the Me-163 where you're
sitting squeezed in between two tanks of hydrogen peroxide at your sides.


I always think flying an Me-163 in combat must have been one of the most
crazy experiences in wartime aviation, firstly you have all the explosive
fuel around you, secondly you are shortly to be boosted at tremendous climb
rates into the middle of a heavily armed B-17 formation, thirdly if you
survive all that and manage to get a shot in before the couple of minutes
before the motor dies, you have to glide back like a brick to a tiny
airfield and land on a skid!


  #6  
Old January 11th 07, 09:00 PM posted to rec.aviation.piloting,sci.space.history,sci.space.shuttle
Pat Flannery
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Posts: 72
Default Why does the shuttle throttle on ascent?



MichaelJP wrote:
I always think flying an Me-163 in combat must have been one of the most
crazy experiences in wartime aviation, firstly you have all the explosive
fuel around you, secondly you are shortly to be boosted at tremendous climb
rates into the middle of a heavily armed B-17 formation, thirdly if you
survive all that and manage to get a shot in before the couple of minutes
before the motor dies, you have to glide back like a brick to a tiny
airfield and land on a skid!


As a glider it was superb, thanks to Lippisch's background as a glider
designer.
Although the pilots tended to dive away at high speed to escape enemy
fighters once their fuel was gone (and to get back to base ASAP for the
same reason), it had a really good gliding performance, and the pilots
who flew it said its handling qualities were superior to any other
German aircraft.
It's only drawback in gliding flight was that it was _too_ good at it -
once it got down in ground effect near landing, it had a tendency to
just float along above the ground till speed bled off and it would
settle down. Even the addition of underwing extensible spoilers didn't
completely solve the problem, and a lot of pilots were injured or killed
by the aircraft remaining stubbornly airborne down the whole length of
the landing field (they landed on grass generally) and not touching down
till it arrived on the rough ground outside the field's boundaries.

Pat
  #7  
Old January 12th 07, 10:25 AM posted to rec.aviation.piloting,sci.space.history,sci.space.shuttle
MichaelJP
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Posts: 8
Default Why does the shuttle throttle on ascent?


"Pat Flannery" wrote in message
...


MichaelJP wrote:
I always think flying an Me-163 in combat must have been one of the most
crazy experiences in wartime aviation, firstly you have all the explosive
fuel around you, secondly you are shortly to be boosted at tremendous
climb rates into the middle of a heavily armed B-17 formation, thirdly if
you survive all that and manage to get a shot in before the couple of
minutes before the motor dies, you have to glide back like a brick to a
tiny airfield and land on a skid!


As a glider it was superb, thanks to Lippisch's background as a glider
designer.
Although the pilots tended to dive away at high speed to escape enemy
fighters once their fuel was gone (and to get back to base ASAP for the
same reason), it had a really good gliding performance, and the pilots who
flew it said its handling qualities were superior to any other German
aircraft.
It's only drawback in gliding flight was that it was _too_ good at it -
once it got down in ground effect near landing, it had a tendency to just
float along above the ground till speed bled off and it would settle down.
Even the addition of underwing extensible spoilers didn't completely solve
the problem, and a lot of pilots were injured or killed by the aircraft
remaining stubbornly airborne down the whole length of the landing field
(they landed on grass generally) and not touching down till it arrived on
the rough ground outside the field's boundaries.

Pat


Thanks Pat - the ME-163 is modelled in the superb combat flight sim IL-2,
trying it last night they must have modelled this aircraft quite nicely as I
found it very difficult to bleed off enough speed in the hold-off, exactly
as you said above. Landing on the grass the skid dug in and certainly a real
aircraft would have been destroyed.

Difference is I could reset for another go

Doing some other testing I found it impossible to recover from a spin
entered from a slow-speed stall. Wonder if that's correct?


  #8  
Old January 13th 07, 03:49 AM posted to rec.aviation.piloting,sci.space.history,sci.space.shuttle
Pat Flannery
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Posts: 72
Default Why does the shuttle throttle on ascent?



MichaelJP wrote:
Thanks Pat - the ME-163 is modelled in the superb combat flight sim IL-2,
trying it last night they must have modelled this aircraft quite nicely as I
found it very difficult to bleed off enough speed in the hold-off, exactly
as you said above. Landing on the grass the skid dug in and certainly a real
aircraft would have been destroyed.

Obviously somebody did their research when writing the program for it.
It might have something to do with the fact tat the ailerons also serve
as its elevators.
Does the simulator have the spoilers on it?
The controls for them are located just to the left of the control stick.
There's a manual pump mechanism handle with a ball top, and to the rear
of it the actual flap control lever.
On the actual aircraft you turn the control handle 180 degrees, then
pump the pump handle six times to put the flaps fully down.
Difference is I could reset for another go

Doing some other testing I found it impossible to recover from a spin
entered from a slow-speed stall. Wonder if that's correct?

It's supposed to have a very abrupt and severe stall according to Eric
Brown's flight notes; he states it goes into a steep spiraling dive, but
you can recover from it in a "straightforward" manner. I don't know it
that means you turn into the spin and convert it into a dive or what.
BTW, he was able to get the one he was flying up to 440 mph in _gliding_
flight in a dive, which gives you some idea of just how aerodynamic this
little thing was.
He wrecked his Komet by doing progressively faster and faster ballasted
landings as tests for a British high speed research aircraft that the
RAF was planning, till the skid finally came through the floorboard of
the cockpit after a landing at 158 mph.

Pat
  #9  
Old January 15th 07, 10:28 AM posted to rec.aviation.piloting,sci.space.history,sci.space.shuttle
MichaelJP
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Posts: 8
Default Why does the shuttle throttle on ascent?

MichaelJP wrote:
Thanks Pat - the ME-163 is modelled in the superb combat flight sim IL-2,
trying it last night they must have modelled this aircraft quite nicely
as I found it very difficult to bleed off enough speed in the hold-off,
exactly as you said above. Landing on the grass the skid dug in and
certainly a real aircraft would have been destroyed.

Obviously somebody did their research when writing the program for it.
It might have something to do with the fact tat the ailerons also serve as
its elevators.
Does the simulator have the spoilers on it?
The controls for them are located just to the left of the control stick.
There's a manual pump mechanism handle with a ball top, and to the rear of
it the actual flap control lever.
On the actual aircraft you turn the control handle 180 degrees, then pump
the pump handle six times to put the flaps fully down.


Don't think so, but it does have landing flaps. IL-2 is pretty good as a
simulator but it models 100's of different aircraft and variants so it has
to make compromises and not all the subtleties are there. Amazing value
though for the price.

Difference is I could reset for another go

Doing some other testing I found it impossible to recover from a spin
entered from a slow-speed stall. Wonder if that's correct?

It's supposed to have a very abrupt and severe stall according to Eric
Brown's flight notes; he states it goes into a steep spiraling dive, but
you can recover from it in a "straightforward" manner. I don't know it
that means you turn into the spin and convert it into a dive or what.
BTW, he was able to get the one he was flying up to 440 mph in _gliding_
flight in a dive, which gives you some idea of just how aerodynamic this
little thing was.
He wrecked his Komet by doing progressively faster and faster ballasted
landings as tests for a British high speed research aircraft that the RAF
was planning, till the skid finally came through the floorboard of the
cockpit after a landing at 158 mph.

Pat


Interesting, what's your source for the Eric Brown story, I'd like to read
more.


  #10  
Old January 8th 07, 11:30 PM posted to rec.aviation.piloting,sci.space.history,sci.space.shuttle
Henry Spencer
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Posts: 16
Default Why does the shuttle throttle on ascent?

In article ,
Morgans wrote:
I had always heard that the fuselage tank was the source of the instability,
with it being so far behind the CG, to give it a dangerously aft CG. Today,
in peacetime, I don't suppose they would ever dream of putting that much
weight that far back, but it was war.


Yep, lots of compromises in some of those wartime designs... Some of the
photo-recon versions of the Spitfire had a tail tank that compromised
stability even more drastically: the aircraft was outright aerodynamically
unstable with that tank full or nearly full. (Naturally, you emptied that
tank *first*... and didn't have much attention to spare for anything else
until it was empty.)
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |
 




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