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Author
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Topic: X-15 rocket plane flight and program plans
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Jim_Voce
Member Posts: 273
From:
Registered: Jul 2016
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posted 06-12-2018 11:43 AM
   
The X-15 as a concept was formulated in 1954 and it started off with a 16,000 lbs thrust engine. Eventually the engines of the three X-15 aircraft were upgraded to a 57,000 lbs. thrust engine and it was this engine that gave the aircraft the capacity to travel to a 50 mile high altitude and higher.Does anyone know if back in 1954, it had always been planned that the X-15 would attempt to travel in the disputed zone boundary of space (50 miles high and above)? Or were these spaceflights added on to the program later? One clue to this is that the so-called "big engine" — the XLR-99 that made the X-15 spaceflights possible — began development as early as 1956. But it wasn't flight ready until November 1960. And the first XLR-99 was installed in an X-15 in 1961. The X-15 had begun unpowered test flights in June 1959. So by the time a spaceflight ready version of the X-15 was available, the plane had been flying for two years. So at a glance, it seems that plans for a 50 mile high X-15 flight might have started as early as 1956, but may be not. The big engine was designed mostly for speed. So perhaps this was the goal in 1956, a high speed flight, with the idea of a 50 mile high flight coming about later. My second question concerns the number of X-15 flights made: There were a total of 199 X-15 flights with the last one coming in 1968. Does anyone know why the program lasted so long and why so many flights were made? It has been speculated that the X-15 flights were tied into space shuttle development work. But there is no direct link between these programs that I am aware of. So this leaves me wondering what value NASA and the Air Force placed in the X-15 program in the late 1960s given the fact that orbital spaceflights had been happening and super fast planes like the SR-71 had entered operational status. And my final question is, the X-15 Program was a joint NASA/Air Force Program. But who "owned" the X-15 Program more in terms of funding it — the Air Force or NASA? |
Jim Behling
Member Posts: 1463
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 06-12-2018 02:46 PM
The design spec was both for high altitude and high speed (250K ft and 4500 mph) using a 57k lb thrust engine. There was no "spaceflight" version. All had thrusters. Just different engines because of engine development delays and early flights would be constrained anyways.The X-15 was primarily for researching speed. Altitude wasn't a goal. quote:
Originally posted by Jim_Voce
Does anyone know why the program lasted so long and why so many flights were made?
Because it was providing valid research data on hypersonics and it was good experiment platform (it was used like a sounding rocket) It was much faster than an SR-71. quote:
...the Air Force or NASA?
Equal. Air Force bought the craft but NACA/NASA paid for the operations. |
Jim_Voce
Member Posts: 273
From:
Registered: Jul 2016
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posted 06-15-2018 01:55 AM
Were the specs of an altitude of 250,000 feet dated all the way back to the beginning of the program in 1954 when the Request for Proposals were handed out?Also, 250,000 feet equals 47 miles high altitude. That is practically the same as 50 miles, which at the time was considered the boundary of space. So I suppose we could say that 47 miles high was considered the boundary of space more or less back then. If the vehicle specifications did call for a 250,000 feet altitude capability, wouldn't it be accurate to say that reaching "space" was one of the initial goals of the program? |
oly
Member Posts: 905
From: Perth, Western Australia
Registered: Apr 2015
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posted 06-15-2018 05:17 AM
To state a service ceiling of 250,000 feet does not mean that the aircraft falls apart at 250,001 feet, it is designed to say that the aircraft must be capable of operation at the conditions found at that altitude. Given that the atmospheric conditions and the aircraft's ability to operate in such a realm, flying higher was not that more complicated. The aircraft, once dropped from the B-52 aircraft, would used the rocket engine to accelerate and climb in an arc. If the flight was an altitude run, the arc was flown at a steeper incline, if it was a speed run, more thrust was converted into speed than altitude. More fuel equals more altitude.
The aircraft was operated for so long because it was still returning some useful data, or giving the operators some value and its operation could be justified. |
Jim Behling
Member Posts: 1463
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 06-15-2018 08:32 AM
quote:
Originally posted by Jim_Voce:
...wouldn't it be accurate to say that reaching "space" was one of the initial goals of the program?
No, just because it is 250K feet doesn't mean "space" is a goal. It is not "space" as far as altitude or velocity. | |
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