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Re: The Fully Reusable Access to Space Technology (FAST) Program

flateric

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AFRL Tests Potential Space Vehicle Designs
February 5, 2008

AFRL researchers recently tested six different hypersonic vehicle configurations to learn about the flight characteristics of potential reusable space vehicles. The series of tests, conducted at the Arnold Engineering Development Center’s hypervelocity tunnel 9, is part of the High-Alpha Reusable Launch Vehicle (RLV) Aerodynamic Configuration Development program. The purpose of the test effort was to gather data on the different vehicle configurations and validate the computational fluid dynamics (CFD) codes used for predicting airflow around the vehicles.

Of the six vehicle configurations tested, the AFRL High-Speed Configurations team developed five. The remaining test configuration was the Hot Eagle design, developed by Conceptual Research Corporation. All six configurations represent reusable second-stage hypersonic vehicle designs.

Each configuration underwent tests at Mach 14 speeds and 30°-75° angles of attack. Under these conditions, researchers gathered stability, pressure, and heat flux data for each vehicle design, completing all tests successfully. The results will assist researchers in modifying the computational modeling processes and approaches, as well as identifying the areas in which CFD codes were unable to accurately model the airflow. The data will also assist AFRL’s in-house reentry vehicle design studies. Overall, these tests expanded the knowledge base pertaining to hypersonic flight, since existing literature contains no data regarding high angles of attack >50° on complex configurations.

High-alpha RLVs are reusable space access vehicles that could potentially carry payloads into space and return for quick-turnaround reuse, saving time, money, and manpower. These vehicles may also provide benefits in terms of increased reliability and safety.

http://www.wpafb.af.mil/shared/media/document/AFD-090205-085.pdf
 

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antigravite

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looks like some later variant of the X-42 or a cross variant of Raymer's Micro-X combined with X-37.
 

flateric

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IMHO, looks like grumpy Physeter catodon
 

Matej

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Orionblamblam said:
That's a screwy tail arrangement. Either the V-tail on the centerbody, or the tip-fins on the wings... but *both*?

I agree. But we saw a three "tail" configuration on various X-24 and FLD series planes, so this is probably continuance. However I am not sure, what aerodynamic benefits the V-tail combined with tip-fins has.
 

Desert Dawn

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Matej said:
Orionblamblam said:
That's a screwy tail arrangement. Either the V-tail on the centerbody, or the tip-fins on the wings... but *both*?

I agree. But we saw a three "tail" configuration on various X-24 and FLD series planes, so this is probably continuance. However I am not sure, what aerodynamic benefits the V-tail combined with tip-fins has.


It's not unheard of. The Lockheed HGV made use of a very similar 4 fins configuration. The general wing and body shape was also relatively similar (albeit more blended). A single vertical on the fuselage would have to be taller, bigger, might interfere with the shockwave, two smaller ones stay within the shock and provide the stability that a shorter single fuselage fin might not provide. For the two outer wing fins, i don't know, but it seems they need them here or they would not have enough stability for this configuration.

What i find strange is that they are still playing with an old wing-body shape. Perhaps it's just because they want to build it out of carbon fiber ? (and use tiles for TPS)(rather than an all metal low lift-to-drag ratio lifting body shape which would be much more slender). Or it's just they don't want to show us any new lifting body shapes they've got today.
 

quellish

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Desert Dawn said:
It's not unheard of. The Lockheed HGV made use of a very similar 4 fins configuration. The general wing and body shape was also relatively similar (albeit more blended). A single vertical on the fuselag woul have to be taller, bigger, might interfere with the shockwave, two smaller ones stay within the shock and provide the stability that a shorter single fuselage fin might now provide. For the two outer wing fins, i don't know, but it seems they need them here or they would not have enough stability for this configuration.

I have seen another Lockheed shape with four short tails, but it was unusual in other ways as well. Shallow dorsal inlets, and a lo-flyte like shape. In fact, quite a bit like this:
http://www.yojoe.com/vehicles/88/phantom/
(cross bred with loflyte)
No, I'm not kidding.

Desert Dawn said:
body shape which would be much more slender). Or it's just they don't want to show us any new lifting body shapes they've got today.

From what I have heard there were issues making the first HTV vehicle out of carbon, and that was a relatively easy shape. All of the FALCON/HTV shapes I have seen have been recycled from other programs like HPMARV, nothing new or revolutionary.
 

Orionblamblam

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Desert Dawn said:
What i find strange is that they are still playing with an old wing-body shape. Perhaps it's just because they want to build it out of carbon fiber ? (and use tiles for TPS)(rather than an all metal low lift-to-drag ratio lifting body shape which would be much more slender). Or it's just they don't want to show us any new lifting body shapes they've got today.

A lifting body is a bad shape for a booster. If you want a reusable booster stage, as opposed to an orbital stage, you want as simple and lightweight as you can get... and that means either ballistic recovery (Nexus, SERV, Delta Clipper, ROMBUS/Ithacus, SASSTO, etc.), or wing-body.

A booster with a separation speed of Mach 5 or less would need very little in the way of exotic TPS. Large designs, such as the winged S-IC and StarBooster concepts, could get away with a simple heat soak structure made out of aluminum, with titanium or steel in a few spots. Since this Lockheed rocket is based on the same basic geometry as the later StarBoosters, there's no reason to assume it would need anything more exotic.
 

flateric

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quellish said:
From what I have heard there were issues making the first HTV vehicle out of carbon.

So much issues, that HTV-1 was plain cancelled.
 

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