From: bowers@rigel.dfrf.nasa.gov (Al Bowers)
Subject: Re: F-23 Dead?
Organization: NASA Dryden, Edwards, Cal.
	<SHAFER.92Sep10180355@ra.dfrf.nasa.gov>
Date: Mon, 14 Sep 1992 22:15:48 GMT

In article <SHAFER.92Sep10180355@ra.dfrf.nasa.gov> shafer@rigel.dfrf.nasa.gov (Mary Shafer) writes:

>On 10 Sep 92 20:25:58 GMT, tpickett@auspex.com (Tom Pickett) said:

>Tom> In article <BuDGBo.GG2@ais.org>, draper@ais.org (Patrick Draper) writes:
>> I thought that the F-15 could accelerate straight up. I read in a book once
>> that it could actually surpass the speed of sound in a tru vertical climb,
>> and if it was already airborne at ground level, it could beat the space
>> shuttle to 50,000 feet in a vertical climb.
>> 
>> I read it in a book, so it *must* be true, right?

>Tom> Of course it's true.  As long as no additional items are hung out on
>Tom> the wings/fuselage, etc... .

>Not quite true.  Some external stores don't have much effect.  For
>example, loading out with Sidewinders and Sparrows doesn't give you
>a lot more drag.  Centerline drop tanks and 500-lb bombs do.

>Tom> Once you add drag and weight onto the aircraft it becomes considerably
>Tom> more "dirty" and not as aerodynamically efficient.  An F-15 at gross
>Tom> weight is not likely to have a thrust to weight ratio in excess of 1,
>Tom> and therefore cannot climb vertically.  Additional degradation occurs
>Tom> with added drag in the form of missles, fuel tanks allowing more than
>Tom> an hours flight time, and so on.

>An F-15 at gross weight has a T/W > 1.  I don't remember how much greater
>(it's been a lot of years since I worked on the Cat I testing of the
>F-15) but it's sufficient.  Slipper tanks don't add enough drag to
>notice, either.

Note: Sidewinders weigh in at about 220 pounds a piece and Sparrows
are about 340 pounds a piece.  Phoenix's weigh in at around 600 pounds
a piece.  It doesn't take too many missles loaded up to do in your T?W
ratio.

>Tom> Also don't forget that the space shuttle is very heavy and it would
>Tom> logically take awhile to accelerate sufficiently to overcome its mass,
>Tom> hence I suppose under ideal conditions, maybe a fighter could out
>Tom> climb it, but I doubt it.  Many fighter aircraft have incredible
>Tom> initial climb performance (the F-104G climbed at 70K fpm according to
>Tom> Jane's), but they slow down considerably as the altitude increases.

>Both the F-15 and the F-104 can fly a Shuttle launch profile up to
>about Mach 2.2.  We did this for some Shuttle tile tests.  Neither
>were in MAX for the entire profile, indicating that they could have
>outperformed it.

Note that all the F-104 and F-15 profiles flown are _*NOT*_ launch
profiles (the current winds data done with a lightweight F-104 is done
in _TWO_ zooms to get to 60,000 feet).  Most of these were Reynold's
number profiles, not Mach profiles or Mach/Altitude profiles.

The F-15 Streak Eagle (a one of a kind F-15) had a T/W at take-off of
about 1.2 to 1.4 to 1.  This airplane was specially lightened to fly
time to climb record profiles.  I expect a stock F-22 to beat it.

Also, with a combat load TOGW, the T/W of an F-15 is about 0.85
(depends on the load, with no 'winders on, it approaches 1:1 at TO).
Note that the Su-27 that made the trip to Farnbourough two years ago,
took off at Moscow and made the 4,800 mile trip _UNREFUELED_ (take-off
T/W of 1.1, at landing it is about 1.6:1!).

--
"But the fact that a 1938 touring bodied Alfa Romeo I once had is
worth $1 million sometimes bothers the hell out of me.  It's a
personal problem."                                     -Phil Hill
Al Bowers                                 bowers@rigel.dfrf.nasa.gov
Iaido   Takamine   Hobie   Rossignol   Alfa Romeo  Ducati (DOD #900)
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