kb6kgx Loc: Simi Valley, CA

That’s really what I meant: “Home” base.

kb6kgx Loc: Simi Valley, CA

Think you meant, “LEAKS like a fountain pen”! :)

kb6kgx Loc: Simi Valley, CA

High school buddy of mine, his dad was with the “Combat Camera” unit. You should see HIS photos! Even got to fly rear seat with Chuck Yaeger!

LFingar Loc: Claverack, NY

What was he flying in with Yeager, and where? That would be an interesting story.

kb6kgx Loc: Simi Valley, CA

I’ll try and find the photo he posted on Facebook and repost it here.

billc987

The SR-71 is indeed a fast craft but it was not the first or the fastest of its kind. That would be the Oxcart A-12. It was rated at MACH 3.5 while the SR_71 is MACH 3.2 and the operational ceiling was 95,000' vs 85,000 '

LFingar Loc: Claverack, NY

Both planes exceeded those figures in actual operation. As fuel burned off during the missions the cruise altitude and speed would increase. There have been references to the SR-71 reaching 100,000' or higher. How fast or how high either could go has never been officially listed, so far as I know. The A-12 could be expected to have a bit more speed (Mach 3.35, not 3.5) and altitude. Empty it was 7,500 lbs lighter then the SR. What the A-12 lacked in comparison to the SR was un-refueled range (750 mi less) and 1000lb less sensor payload. Another problem was that because both planes were so demanding to fly the single man crew of the A-12 was often under extreme load. The A-12 was superior in some aspects, but for the intelligence gathering that needed to be done, the numbers favored the SR-71 by a wide margin.

Caysnowman Loc: MN & SC

Do you by chance know if the engine inlet spike control automatic or did it have a manual back-up / over ride.

Bil

LFingar Loc: Claverack, NY

Automatic, although I imagine the pilot had some type of over ride in the event of an unstart.

kb6kgx Loc: Simi Valley, CA

Haven’t found the pix with Yeager, yet, but here are some that my friend’s dad took of the SR-71 during refueling from a KC-10.

wdross Loc: Castle Rock, Colorado

One of the other automatic features was automatic engine shut down in case of single engine flame out. When the engines are running at full blast, if one engine flames out, the other engine had to be shut down within a half a second. Because the engines were so powerful and located far enough from the center line and center of mass, if an engine flames out, the other engine will rotate the plane sideways to the direction of travel. Needless to say this did cause a catastrophic failure and the loss of one plane. All the others were then fitted with automatic shut down in case of single engine flame out.

LFingar Loc: Claverack, NY

You may be confusing an unstart with a flame out. Unstarts were very common in the A-12, and were very violent events. At that time inlet spikes were controlled manually and the pilot often was not precise enough to prevent the unstart. An analog control system was designed that went into the SRs. It helped, but did not cure the problem. A digital system was then developed and retrofitted. It eliminated the vast majority of unstarts. I think it still offered some manual control to the pilot, but normally it reacted so quickly that no intervention by the pilot was necessary. On the A-12 it was not unheard of for repeated unstarts of both engines to occur. An unstart would only occur over Mach 1, (1.6, I believe) and was usually more dangerous then a flame out, which was rather uncommon, I believe. An unstart not only caused the engine to lose most of its thrust but the aerodynamic effects of it caused a huge amount of drag momentarily. The plane would yaw violently. Pilot's helmets were actually cracked from hitting the edge of the cockpit.

bemused_bystander Loc: Orkney Islands, UK

Could you explain more about the difference between an unstart, and a flame-out? (I do know roughly what a flame out is)
Please forgive my ignorance.:)

wdross Loc: Castle Rock, Colorado

I suspect you are correct. It was told to me as a flame out, but it probably was the failure of the ram portion starting up. I am sure either would have resulted in the same results at high speed with the kind of power in those engines. Although I knew that if it was uncontrolled, it was catastrophic, I had not heard the part about how the pilots got thrown around even with the safe guards.

LFingar Loc: Claverack, NY

A flame out is usually, but not always, caused by a lack of fuel flow and is a relatively slow event, occurring over a period of several seconds, even minutes. An unstart occurs in a fraction of a second. At speeds above Mach 1 (Mach 1.6, if I remember correctly) a supersonic shockwave forms in the intake ducting. At that point the intake is considered "started". The intake spike controls the position of the shockwave by moving backwards a total of 3 ft as speed increases. The shockwave forms at the point where the airflow slows to subsonic speed. Turbine engines cannot ingest supersonic air flow. It can destroy them. One of the jobs of the intake is to slow the airflow. Look at an F-4 Phantom and you will see large flat plates at the engine inlets. These are gates that move in and out to regulate air flow for the same reason. At high Mach the intake system of the SR, because of internal pressure differentials, is actually producing more thrust then the engine or afterburner. An unstart occurs when the shockwave is ejected out of the front of the intake. The intake spike being slightly out of position causes this as I understand it. The intake is no longer started. It is now considered unstarted. The engine does not flame out but power output, especially from the intake, drops dramatically. The shockwave popping out of the front of the engine produces a huge amount of drag momentarily. This all happens in a fraction of a second and produces a violent yaw of the plane. On the SR's the automatic intake control would instantly reposition the intake spike to restart the intake. On the A-12's this had to be done manually and if the pilot couldn't achieve it at supersonic speed he would have to slow the plane to subsonic and basically start all over.

No ignorance on your part. Unless you have filled your head with tons of relatively useless knowledge over the years, as I have, you, like the vast majority of normal people, have probably never heard of an unstart before!