Why does the shuttle throttle on ascent?

Mxsmanic wrote:
One wonders what sort of emergency would justify running the engine a
bit faster for just ten minutes, and then replacing the entire
aircraft.

uh, you realize they were getting shot at and whatnot, right?

"Danny Deger" wrote in message ...
:
: "Danny Deger" wrote in message
: ...
:
: Why does the shuttle throttle to 3 Gs on ascent?
:
:
: The 3 G throttling is done late in the flight (about 7:30)and has nothing to
: do with dynamic pressure. It was designed in to allow "regular" people fly
: the shuttle.
:
:

Yes, the aerodynamic loads are highest early in the flight so the engines are throttled then back up. The shuttle rolls
over on its back to fake the occupants into feeling 3 gs when in fact the vehicle is pushing 4 gs....

"Blueskies" wrote in message
. net...

"Danny Deger" wrote in message
...
:
: "Danny Deger" wrote in message
: ...
:
: Why does the shuttle throttle to 3 Gs on ascent?
:
:
: The 3 G throttling is done late in the flight (about 7:30)and has
nothing to
: do with dynamic pressure. It was designed in to allow "regular" people
fly
: the shuttle.
:
:

Yes, the aerodynamic loads are highest early in the flight so the engines
are throttled then back up. The shuttle rolls
over on its back to fake the occupants into feeling 3 gs when in fact the
vehicle is pushing 4 gs....

No.
The 3 Gs is at the backs of the occupants (and along that same axis for the
vehicle.) This is the same if they are heads up or heads down.
If you lie with your back on the floor, you feel the same 1 G if your head
is facing north or south.

Tim

In article ,
says...
Pat Flannery writes:

On the P-51 Mustang, this was called "War Emergency Power"; it would
give some extra zip, but would also destroy the engine in around ten
minutes after engaging it. :-)

One wonders what sort of emergency would justify running the engine a
bit faster for just ten minutes, and then replacing the entire
aircraft.

saving yer bacon comes to mind.

--
Duncan

Mxsmanic wrote:

One wonders what sort of emergency would justify running the engine a
bit faster for just ten minutes, and then replacing the entire
aircraft.


I think it probably had something to do with a FW-190D being around 400
feet behind you. :-)

Pat

Danny Deger wrote:

"Danny Deger" wrote in message
...

Why does the shuttle throttle to 3 Gs on ascent?



The answer is:

So Navy Fighter pilots can fly the shuttle :-)

Danny Deger

P.S. I was an Air Force figher pilot.




Flare to land, squat to pee.

"Blueskies" wrote in message
. net...


snip

Yes, the aerodynamic loads are highest early in the flight so the engines
are throttled then back up. The shuttle rolls
over on its back to fake the occupants into feeling 3 gs when in fact the
vehicle is pushing 4 gs....



For some time now the shuttle rolls to heads up well before 3 G throttling.
This is done so the antennas can communicate with the TDRS satellites.

Danny Deger

"Pat Flannery" wrote in message
...


Morgans wrote:

Of course, on some engines, that was grounds for grounding the aircraft
to inspect the engine, to see if it was damaged from exceeding 100%
power.

On the P-51 Mustang, this was called "War Emergency Power"; it would give
some extra zip, but would also destroy the engine in around ten minutes
after engaging it. :-)

Pat

Actually it's 5 minutes. WEP on my V1650-7 Merlin in the 51 could be
achieved by breaking the throttle gate . I never used it...actually never
needed it really. Under 5000 feet, normal max power at 61 inches gives you
all the power you need to exceed the operating limitations for the engine,
and at altitude on cross country, I was more concerned with saving a buck by
not stressing the engine anyway :-)
Also, if breaking the gate and using that extra 6" of MP, the Mustang should
be using 130 octane fuel and not the 100LL we poor folks have in the tanks
most of the time :-) 100LL limits the 51 to 55 inches anyway, so you can
forget using War Emergency Power for the general Mustang owner (Hoover might
be an exception since he has an expense account most of us envied :-)
I didn't fly the 51 in combat, which I guess is the gist of the discussion,
but in combat, if you used WEP, it was a 5 minute emergency only deal that
meant a complete engine breakdown and inspection within 5 hours. Needles to
say, the 51 drivers in combat didn't misuse their engines by using WEP
indiscriminately. Actually, if you had to go to WEP in combat, you were
almost always defensive against a hard turning opponent, and if you got to
that point, you were in deep do-do already!
Most of the guys flying the 51 in air to air tried to keep the temps down
(Coolant to 121 degrees was a doubtful trip home) For ACM in the 51, 61
inches and 3000RPM will give you a wide airspeed and energy envelope to
maneuver in all 3 dimensions. Going through the throttle gate was a sure
indication you had done something REAL wrong!!
Anyway, hope this helps a bit.
Dudley Henriques

Blueskies wrote:
Yes, the aerodynamic loads are highest early in the flight so the engines are throttled then back up. The shuttle rolls
over on its back to fake the occupants into feeling 3 gs when in fact the vehicle is pushing 4 gs....



That also lowers stress on the wings; the Bomarc ramjet missile used to
roll belly-up on the bearing to its target after liftoff, then turn
right-side up once in basically horizontal flight.

Pat

"Henry Spencer" wrote in message
...

interesting stuff snipped

That said, the SSMEs are cranky, marginal engines, and taking *them* up to
120% (as was once intended) is much more iffy than doing the same for
robust engines like the H-1 or F-1.
--
spsystems.net is temporarily off the air; | Henry Spencer
mail to henry at zoo.utoronto.ca instead. |


Henry,

What makes the SS engines "cranky and marginal" vs the H-1 and/or F-1?

Thanks...

KB