Old airframe, new engine

On 10/20/03 9:42 PM, in article ,
"Mary Shafer" wrote:

On Tue, 21 Oct 2003 01:14:57 GMT, "Doug \"Woody\" and Erin Beal"
wrote:

On 10/20/03 3:06 PM, in article ,
"Mary Shafer" wrote:

Incidentally, most people know that the SR-71 used the dipsy-doodle to
convert potential energy to kinetic energy (altitude to velocity)
through the transonic region. Many people think it could only go
supersonic if it dipsy-doodled, but that wasn't the case. It could
get supersonic flying straight and level, too. However, as soon as it
did, it pretty much had to slow down and go look for the tanker. This
took a little longer than seven minutes, though.

Is the "dipsy doodle" what most fighter pilots refer to as the Ritowski
climb?

I don't know, as I don't know exactly what the Ritowski climb is. I
think it is, though.

Essentially, the SR-71 climbs at constant qbar (400 KEAS) to Mach 0.9,
then descends at a constant rate to Mach 1.25 (450 KEAS at 30,000
feet), and then climbs again at a different constant qbar (450 KEAS)
to cruise.

I would assume so since that's the recommended procedure for getting most
supersonic aircraft going high and fast quickly and without running out of
gas.

Seems reasonable to me that it would work generally, not just for the
SR-71.

Please elaborate. And what were the specifics of the profile for the SR-71
(as long as it's not classified, of course)?

Naturally, I'm here and my Dash-1 is there, so I can't produce the
exact numbers unless they're in the Researcher's Handbook. Let me go
look. OK, I'm wrong, I do have the Dash-1, which was hiding on the
wrong shelf.

I'll still going to look first in the Researcher's Handbook, except
that it doesn't have an index. An index won't help, though, because
"dipsy doodle" isn't exactly an official USAF term. Nada.

OK, here it is from the Dash-1. It's pretty long, but I thought you'd
prefer the exact description, not my briefer version of it. It's "a
climb-and-descent maneuver". You'll have to imagine the typography,
boxes, and indentation yourself, though.

TRANSONIC ACCELERATION PROCEDURE

Transonic acceleration is accomplished at either a level altitude or
during a climb-and-descent maneuver.

NOTE
The climb-and-descent acceleration is recommended for best specific
range (NM per pound of fuel used).

Level Acceleration

A level acceleration to intercept the supersonic climb speed schedule
can be made at refueling altitude, normally 25,000 feet. When ambient
temperatures are near or lower than standard, less time and distance
are required to intercept the climb speed schedule than the
climb-and-descent procedure. The total range penalty is small under
these conditions.

Start the acceleration with minimum afterburner. Complete course
changes while subsonic so that the additional power required for
turning will not diminish the power available for transonic
acceleration. Set maximum power at Mach 0.9. Gently increase pitch
to climb attitude near 430 KEAS. A smooth technique is required, as
450 KEAS is only slightly more than Mach 1.1 at 25,000 feet and is
still within the critical thrust/drag speed range which begins near
Mach 1.05.

WARNING

Airspeed may increase rapidly after Mach 1.1 is reached. Reduce power
(below Military, if necessary) to avoid high airspeeds. Do not use
excessive load factors to prevent exceeding 450 KEAS,

The procedure can be used at another altitude; however, when lower,
the transition to 450 KEAS climb attitude must be made in the
unfavorable speed range from Mach 1.05 to 1.10. At higher altitudes,
the transition through this speed range can be completed before
starting the climb, but less thrust is available. If ambient
temperature increases, thrust decreases and the time, fuel, and
distance penalty for using the level acceleration procedure is
greater.

Climb-And-Descent Acceleration

The climb-and-descent procedure requires less fuel to intercept the
climb speed schedule than the level acceleration when ambient
temperatures are warmer than standard.

NOTE

The climb-and-descent procedure is recommended for best specific range
(NM per pound of fuel used) at all temperatures.

WARNING

Although angle of attack increases during the subsonic climb, pitch
attitude must decrease to avoid dangerous flight conditions. Failure
to monitor and control attitude, speed, and angle of attack can result
in approach to pitch-up conditions.

Start the acceleration with minimum afterburner power. Intercept Mach
0.9. Set maximum afterburner at 30,000 feet for the remainder of the
acceleration, observing the 300 KEAS restriction. At 33,000 feet,
increase speed to at least Mach 0.95. This speed is slightly above
the start of the drag rise region. Make a smooth transition to
establish a 2500 to 3000 fpm rate of descent.

NOTE

Engine stalls during the subsonic climb may indicate a potentially
dangerous flight situation. Stalls can result from low CIP or high
distortion in the inlet associated with aircraft operating beyond
established flight limits. Refer to Subsonic Compressor Stalls,
Section III.

After establishing the descent rate, maintain attitude until
initiating climb. Avoid higher rates of descent since the usual
result is altitude penetration below 29,000 feet and high fuel
consumption. When using the climb-and-descent procedure, it is
important to exceed Mach 1.05 early in the descent, and to avoid
turning until the climb is established. Begin the transition to climb
near 435 KEAS so as to intercept 450 KEAS while climbing.

WARNING

- Airspeed may increase rapidly after Mach 1.1 is reached. Reduce
power (below Military, if necessary) to avoid high airspeeds. Do not
use excessive load factors to prevent exceeding 450 KEAS.
- In turbulence, reduce climb speed as specified in Section VII,
Operation in Turbulence.

This is just over a page, but the SUPERSONIC ACCELERATION PROCEDURE is
two and a third pages.

Mary

Mary,

Thanks for the detailed response. Must come with the retirement. I'm
interested in the 450 KEAS limit and the "Do not use excessive load factors
to prevent exceeding..." comment. What is an excessive load factor in this
flight regime. 1.5G? 2.0G?

The Ritowski climb is essentially the same thing. I think that the numbers
are different for most aircraft, but for the Hornet, it's 400KCAS to .85 in
the mid 30's, push it over to exceed 1.0, and climb supersonic afterward.
Works great on FCF's for the mil lock-up procedure (above 1.23M).

--Woody

Just out of curiosity, Woody, what is the fastest you've had the Hornet in
KIAS and IMN? I had a TPS guy claim 800/1.8 for the C, but I think he was
feeding me pure unadulterated BS. In my brief exposure, I was astounded by
its LACK of speed.

R / John

On 10/21/03 2:35 PM, in article , "John
Carrier" wrote:

Just out of curiosity, Woody, what is the fastest you've had the Hornet in
KIAS and IMN? I had a TPS guy claim 800/1.8 for the C, but I think he was
feeding me pure unadulterated BS. In my brief exposure, I was astounded by
its LACK of speed.

R / John



John,

I've never seen that with my own eyes--and I doubt he has either unless the
jet was slick and new and he had a full tank allocated for just that
purpose. 800/1.8 are the "do not exceed" limits in the book.

I've never had a dedicated hop (or the desire) to make an attempt at them.

Fastest I've had the Hornet was doing the mil lockout test on an FCF about
2-3 years ago in W174C (Key West). I coaxed it to 1.46 at 35,000 in a 20
degree dive down from 45,000 before I got a R DUCT DR caution and had to
slow up. It was a slick jet, and I could have probably gotten it faster...
had it been working correctly.

Most I've ever seen in the HUD is 710 KCAS, but that was at approximately
1.06 at 200 AGL off shore San Diego making a supersonic low pass (combat
spread with my -2) on a Coast Guard cutter we were working with. It was a
LONG run-in for fun/show. As a section, we brought one jet down each side.
I had a slight advantage with the EPE motors. (We had finished a sea
surface search radar test early.) We were configured single centerline
tank, no pylons. I don't think it would have gone much faster than that.

I know you didn't ask, but being a chicken with regard to aviation
physiology, I've never climbed one over 53,000 @ 1.10--and that was circa
1994 out in the R2508 when I was a "Laker." It would have gone much higher
in my opinion.

Got any F-8 or Turkey personal experience numbers you want to share? I'd
assume they'd be much better.

--Woody

doug- Got any F-8 or Turkey personal experience numbers you want to share?
I'd
assume they'd be much better. BRBR

Got my Mach 2 pin in a clean F-4D...

Saw 800 KIAS in a F-16N, at 200 ft AGL over by Yuma...don't know the mach
number...
P. C. Chisholm
CDR, USN(ret.)
Old Phart Phormer Phantom, Turkey, Viper, Scooter and Combat Buckeye Phlyer

On Tue, 21 Oct 2003 12:03:05 GMT, "Doug \"Woody\" and Erin Beal"
wrote:

On 10/20/03 9:42 PM, in article ,
"Mary Shafer" wrote:

Essentially, the SR-71 climbs at constant qbar (400 KEAS) to Mach 0.9,
then descends at a constant rate to Mach 1.25 (450 KEAS at 30,000
feet), and then climbs again at a different constant qbar (450 KEAS)
to cruise.

Thanks for the detailed response. Must come with the retirement.

I thinned the list of newsgroups down so I have a little more time to
type. And I'm a very fast typist.

I'm
interested in the 450 KEAS limit and the "Do not use excessive load factors
to prevent exceeding..." comment. What is an excessive load factor in this
flight regime. 1.5G? 2.0G?

Definitely in that vicinity. Let's see, section 4, probably. Limit
Load Factor Diagram, Symmetrical, Turning, and Rolling Flight,
Transonic Penetration (climb or descent). Symmetrical is 2.0 g up to
Mach 1.80 and rolling is 1.6 g. The absolute most you can pull is 3.5
g symmetrically or 2.8 g rolling, below 50,000 ft, at airspeeds
between 310 and 450 KEAS, at a gross weight of 80,000 to 90,000 lb.
It's less above and below those weights.

And the maximum design qbar works out to 500 KEAS, but the limit
airspeed is 450 KEAS.

The Ritowski climb is essentially the same thing. I think that the numbers
are different for most aircraft, but for the Hornet, it's 400KCAS to .85 in
the mid 30's, push it over to exceed 1.0, and climb supersonic afterward.
Works great on FCF's for the mil lock-up procedure (above 1.23M).

I just didn't know it had a name. I remember this from the optimal
trajectory work done in the '60s, in fact.

Someone has posted the URL for the SR-71 Dash-1, by the way. That was
made from the exact same copy that Dryden copied all of its from, as
it's probably the only formally declassified and marked copy
around--the thing is four inches thick and there wasn't any point in
going through and marking out the classification stamps in more than
one copy, because it's just too much work.

Mary

--
Mary Shafer Retired aerospace research engineer