source?

"Lockheed SR-71, Secret Missions Exposed" by Paul F. Crickmoore. Very good reading if you are interested in SR-71. It's Bruce Andersson of Blackbird.

I think you can take Beepers info, on that.

Again, one can tell the max design speed by looking at the cone-angle . .. as a ss-plane goes faster, the shock-wave starts closing in. If the shock-wave closes-in over the wing and/or control surfaces, big problems arise.

SR71 has two main limiting factors: skin temperature and intake air temperature. IAS at those heights is quite low and handling is very very delicate. SR is quite instable at those speeds and requires computer help to fly straight.

Great airplane, but obsolete.

thanks beep. should make for some good reading. but didn't you mean IAT? IAS should be pretty high :D

No, I mean Idicated Air Speed, not True Air Speed...at those heights IAS is not high at all as air is very thin. You have to fly very fast indeed just to keep the plane from stalling. If you are in "coffin corner" and make a sharp turn you can have inner wing stalling and outer one not. It's more pronounced on U2's but SR-71's were quite demanding to fly at those heights as well according to Crickmore...

Concidering all of the information regarding the aurora it appears that the military's successor to the SR-71 already has nasa's little public project beat by about a decade.

Its just about time for that black project technology to be released into the public realm now that nasa has to develop a space plane replacement for the obsolete shuttle.

true, true. I just misunderstood your point. you were making two points and snuck in a third one on me ;)

btw: inner wing stall can happen on any aircraft if airspeed is too low. remember the "dead man's turn?"

Evidently it worked

This is Overpaid Slacker; I'm at Ron's and forgot my password.

JP

hey JP. any progress on the selection of a s-rifle?

this is ronin; I'm at home and I've lost my mind :D

Test was successful! New speed record (that they'll admit to, anyway) - over Mach 7. Supposedly a test is scheduled for later in the year that will include a portion above Mach 10.

SR-71 is/was not obsolete....

'Withdrawn due to financial constraints and the increasing use of other information gathering methods'.

Use of fixed orbit satellites to replace a free flying aircraft...oopps..

Never mind, it wasn't missed a bit in Gulf War 1 or Afganistan but hey, you get more bucks to go elsewhere.

Airframe was limited by an inlet spike temp max of 427 degrees F.

Mach number may vary with height and outside air temp....

Sorry didn't read the second page.

Crickmore's book is 'one' of the bibles of the SRworld. But check out the SR71 Revealed by Rich Graha and his Tails and legends.
For great pics see Sled Driver and the Untouchables by Brian Shul.
Both are ex-SR pilots, as in operationally qualified drivers, not guests.

But th real winner is the SR-71 Pilots handbook, especially the second edition with additional performance information included.

As for Aurora, well is was linked to a successor to the SR but also to the AMB program which lead to the B-2 Spirit.
Which is correct remains to be seen.

I'd guess that it would not be impossible that the scramjet technology has been refined before and that the X-43 is a way of briniging it into the open, much like the use of the Blackbird by NASA in the 70s...

Gentlemen,

Stalling, or exceeding the wing's critical angle of attack, is not a function of airspeed, whether indicated, calibrated or true. It is only a function of angle of attack. If you exceed the critical angle of attack, whether at 10 knots or 10,000, the wing will depart flight.

This is a pretty common misconception, caused by the fact that pitch is related to airspeed. You climb to altitude, pull on the carb heat, retard the throttle to idle and pull back the stick to maintain altitude. Airspeed decays. Five knots above the stall you feel the pre-stall buffet and the warning horn comes on. At the break, you look up and the airspeed indicator is showing, say, 40 knots. So you think, low speed made me stall. Actually what happened is that in order to maintain altitude you had to continue increasing angle of attack until you reached the critical value.

So you dance on the rudders to avoid inducing a spin, and the nose comes forward. You push the stick forward slightly to break the stall and resume level flight at MCA with the horn going off. Airspeed continues to decay, and pre-stall buffet comes in. This time, you apply full throttle, and the stall is averted. Airspeed picked up when you put the throttle in. Did airspeed save you from the stall? Well yes, sort of, because when you came in with the throttle, you increased airflow over the back of the wing, which had the same effect as decreasing angle of attack in inhibiting flow separation.

Now you climb to altitude again, and this time, you push the nose over into a shallow dive until the airspeed indicator reaches 85 knots. As soon as you nail the entry speed, you abruptly pull in full aft stick and push the left rudder all the way to the floor. With the airspeed indicator reading 85 KIAS, the aircraft departs flight and experiences a rapid rotation to inverted. You hold those control inputs until you see the horizon coming around to the three o'clock position, then you feed in forward stick and apply full right rudder and roll out level Congratulations, you just did a snap roll, sort of a "forward spin" in which the wing departed flight with unequal lift on both wings (when stalled, they still produce lift, but WAY less than when in normal flight) and the aircraft rolled rapidly to the left.

At high altitude, the "coffin corner" finds the a/c between mach overspeed and aerodynamic stall. There is a very narrow operating window here, not just found in spyplanes, but in commercial jets as well! You DO NOT want to stall a swept-wing aircraft at high altitude. Those who have done so report taking 15,000 feet to get it back.

:rolleyes:

:D

Yes, you have it correctly. Remember, you are trying to hold level flight with the power at idle. To do that requires that you pull back on the stick and trade your airspeed for altitude. But the more you pull back the stick, the more you increase angle of attack, which will eventually exceed the critical angle of attack and the wing will stall. Airspeed decay while this is happening is a result of increasing AOA but that's not the same as saying that low airspeed causes the stall.

i'm with ronin and his smiley faces... you guys talk on a different level. that's what i love about forums and this one in particular. there are experts on any subject. for those of us that are a little slow when it comes to big words on aero-physics (if that's even a word) here's a little something to entertain us:

http://www.howstuffworks.com/hypersonic-plane.htm

Well I always tought that stall is caused when air stops following laminar flow over the wing and starts tumbling in chaotical manner.

That being said, there are planes with flat wings using so called "compression lift".

Airflow separation, or the creation of turbulence on the upper surface of the airfoil, is another symptom of excessive angle of attack. Basically the wing is operating at such a high AOA that air cannot smoothly flow around the leading edge and turbulence is the result. Imagine a piece of paper held at 90 degrees to the wind and you get the idea. You can use various tricks to change the contour of the wing (leading edge devices like slats, fixed or movable) or a slot, but with even with that stuff sticking out the wing still has a critical AOA that it will stall at regardless of airspeed.

"Laminar flow" describes an airfoil that has been designed to promote laminar flow over its surfaces, reducing turbulence and lowering drag. We didn't really understand it until the 1930's but it was later used to good effect in the P-51 Mustang. Unless the wing has a very smooth surface, like today's composite wings or very well made riveted aluminum ones, surface imperfections will break up laminar flow, resulting in drag.

We all know that there are symmetrical airfoils out there that defy the old "bernoulli" theorem as to why the wing produces lift. There's a raging debate as to whether lift is caused by the pressure imbalance between top and bottom surfaces, or whether it's a newtonian reaction caused by the wind striking the lower surface of the airfoil and being redirected downward, causing an equal and opposite reaction upward in the form of lift.

And you have probably seen the strakes on an F-18, that run from the wing leading edge up toward the cockpit: these are also useful for producing lift.

John,

I know you have the aircraft and I don't but I understood that the primary reason for the LEX on the F-18 was to induce a stronger vortex over the wing during high alpha flight, such as approach to a carrier and during high energy low airspeed flight, ie in a dog fight.

The vortex generated 'spins' over the top of the wing, effectively increasing the pressure differential with the underside hence allowing higher alpha flight to be maintained or same alpha lower airspeed.

Agree about coffin corner tho and your explanation of how airspeed and AOA relate....

Also spinning a swept wing a/c, BTDT.

You spun a swept-wing AC and are still here to tell about it. That's probably worth a thread of its own. . .

I agree with you about the strake on the F/A-18. There are some folks on the BBS who drive one as their day job . . . maybe they will join in?

The whole concept of Vortex generators and winglets takes the discussion in a whole new direction. . . maybe a new thread for that? And I'd also like to hear from anyone who knows about "upper-surface-blowing" and "under-surface blowing" aircraft that use jet blast from turbofans shot directly of the airfoil to augment lift. . .

But now we are way outside the stick and rudder stuff. . .