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