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SR-71, The Blackbird

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SR-71, The Blackbird

Old 23rd Nov 2021, 22:12
  #181 (permalink)  
 
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The first wind tunnel experiment I helped on was the YF-12 intake. We were sub contracted to Lockheed to run a model of it in our supersonic tunnel. The point went in and out and the petals of the cone behind the spike expanded and contracted to vary the rake of the cone and the gap to the intake rim. The edges of the intake were razor sharp and had to be treated with caution.

Last edited by Ninthace; 23rd Nov 2021 at 22:32.
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Old 23rd Nov 2021, 22:25
  #182 (permalink)  
 
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Originally Posted by JSF-TC View Post
Not an A-12.

NASA operated SR-71 with a prototype linear aerospike engine mounted on top. Search Wikipedia.


My wife worked on it as an intern at NASA Dryden - got at signed picture of it on the office wall.
Found it …thanks !

https://www.nasa.gov/centers/dryden/...ain_H-2280.pdf
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Old 23rd Nov 2021, 22:55
  #183 (permalink)  
 
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I think that was part of the tech risk reduction for the X-33 as described. Seem to remember they couldn't get the thing from not leaking fuel or something
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Old 24th Nov 2021, 03:35
  #184 (permalink)  
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My initial guess that it was the drone mount on the M-21 stands corrected by JSF-TC's interesting insight. Oxcart Project Pilot Frank Murray touches on the drone concept briefly in this excellent talk on his involvement with the A-12, in which he also disparagingly refers to the SR-71 at the "family model" of the Blackbird variants.

If the link below doesn't work, search Youtube for "The Oxcart Story - Frank Murray".

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Old 24th Nov 2021, 09:28
  #185 (permalink)  
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Old 24th Nov 2021, 09:31
  #186 (permalink)  
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Old 24th Nov 2021, 16:20
  #187 (permalink)  
 
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Originally Posted by Rug View Post
...in which he also disparagingly refers to the SR-71 at the "family model" of the Blackbird variants.
Not sure that he's intending to be disparaging: 'family model' is a well used jocular reference to any two-seat aircraft that also has a single-seat version.
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Old 24th Nov 2021, 17:33
  #188 (permalink)  
 
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Salute!

No way is "family model" disparaging. It has been used for decades when the primary model is single seat and the trainer or special mission model requires two seats.

Gums sends...


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Old 24th Nov 2021, 22:28
  #189 (permalink)  
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“They built more of this model here [SR-71] which I call the family model. I’m sorry if any of you guys are SR drivers, I don’t have a helluva lot of good to say about it. I never flew that thing either thank God…”

Not a glowing opinion by any means but yes, all delivered with a smile and to laughter so friendly rivalry no doubt.
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Old 25th Nov 2021, 01:12
  #190 (permalink)  
 
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Originally Posted by Flugplatz View Post
I think that was part of the tech risk reduction for the X-33 as described. Seem to remember they couldn't get the thing from not leaking fuel or something
The composite tank was very challenging, with engineering conflicts that eventually caused Lockheed to switch to an aluminium design. Sadly that pretty much killed the SSTO capability of the X-33, metal was too heavy.
The sad result was the entire effort was cancelled, a major loss imho. It signaled the beginning of the era of stagnation in the US space program, decades of Titan and Delta launches with no expectations of anything better.
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Old 25th Nov 2021, 02:04
  #191 (permalink)  
 
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I wonder if they could build the X-33 now, given the advances in composites and manufacturing over ensuing decades?
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Old 25th Nov 2021, 10:31
  #192 (permalink)  
 
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If you listen to Musk in this recent 21-Nov-2021 talk and Q&A etc with (US) National Academies of Sciences (etc)
(or https://forum.nasaspaceflight.com/in...?topic=55237.0) he discusses the issues with composite tanks. It is a long talk and worth listening to in its entirety. In respect of the tanks he notes the porosity/leaks aspects, the flammability aspects (LOX + carbon + high pressure = bang), the weight, the strength (at pressure + low temp), the cost, and the re-entry (heated strength) and the overall airframe weight fraction that comes from this. That is what led to Space-X's decision to ultimately select and develop a stainless steel grade for the Starship as he explains. He also explains the corresponding decisions on Falcon 9. Remember that Space X started off with some very big composite structures in the early stages of Starship, back when they were going with conventional wisdom, so it is not as if Space-X didn't try the composite route. You can see some of the composite tooling etc that was their original pathway for Starship in ( https://www.teslarati.com/spacex-all...p-super-heavy/ )

So you could say that the lessons of X-33 were learnt, eventually.
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Old 25th Nov 2021, 23:09
  #193 (permalink)  
 
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Agree Etudiant,
Not following through with the X-33 tests of represents (to me) when NASA sort of lost their 'mojo' in terms of cutting edge launch vehicles/aerodynamics. They've still got it with their exploration spacecraft and science goals, but I guess the baton has now been passed to innovators like Space X. At least NASA have got behind Space X and that arrangement seems to be working pretty well.

Actually, the Lockheed team did build a metal internal tank, which eventually came within the required weight, so it could have been used. The testimony of NASA director Ivan Bekey was pretty much the final nail in the coffin. There is something about the whole project, which is sadly reminiscent of the dumping of the TRS 2
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Old 26th Nov 2021, 00:17
  #194 (permalink)  
 
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Shame.
It kind of `looked right' as Kelly used to say...
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Old 26th Nov 2021, 08:16
  #195 (permalink)  
 
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@ORAC , that’ s where the pictures come from .
They where testing the plumbing of the system ( cold flow ) in a series of flights , they ignited the propellant only in ground test .
https://www.nasa.gov/centers/dryden/...sre/index.html
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Old 26th Nov 2021, 16:31
  #196 (permalink)  
 
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Originally Posted by Nick 1 View Post
@ORAC , that’ s where the pictures come from .
They where testing the plumbing of the system ( cold flow ) in a series of flights , they ignited the propellant only in ground test .
https://www.nasa.gov/centers/dryden/...sre/index.html
I don't know whether the X-33 engine was ever tested at full scale. It certainly had an impressive plumbing complex above the simple looking linear aerospike.
How robust the whole thing would have been is unknown, but weight was always the SSTO bugaboo, so margins were minimal everywhere.
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