Friday, September 01, 2006

Spacecraft are NOT Airplanes I

A fellow space-geek discusses the new CEV, and gives some very good commentary on the significant advantages of capsules over "space-planes", which exist in the public mind in that annoying, fixed, way-things-are-going-to-be-to-the-exclusion-of-every-other-possibility type mindset. I agree, and have commented about this before on various forums that there is only 1% of a spacecraft's mission profile where wings are anything but a hobbling disadvantage.

His podcast is here:


Blogger Randy said...

I haven't had a chance to review the podcast yet, nor really have seen your thoughts on capsules vs spaceplanes, but...

From experiance I can tell you it's an uphill battle all the way :o)
Good luck with it.

The 'problem' I've found is the various 'views' on what is a 'capsule' or non-lifting design, and what is a 'spaceplane' or lifting design.
The differences can (at times) be vauge at best.

I personally have been involved in a continious 'discussion' with some folks for over 5 years now on the benifits vs the penalties of both designs with little 'head-way' made.

It's probably because the defintion of 'capsule' they insist is "Mercury/Gemini/Apollo" and can never be reused or made reusable. While they insist that 'winged/lifting' includes just about every other reusable design proposed including the DC-X which they 'swear' was supposed to be a lifting body :o)

Sorry for the ramble, to sum up I guess;
While 'spacecraft' are not 'airplanes' neither are they ballistic missiles with crew cabins on top.
You state that there is 'little' of the flight trajectory where wings are anything but baggage. This is not a 'given' since 'wings' are not the only methods of 'lift' and there are areas of take off, landing, flight and reentry where lift can greatly reduce vehicle complexity and mass. On the other hand, there are areas where ballistic flight are both better and more economical. It's not a "black-or-white" yes or no type question, but a deliberate design decision and balance of trade offs of one vs the other.


Wednesday, September 06, 2006 6:40:00 PM  
Anonymous Gordon said...

When you look at the old (1950's) Von Braun photos he's usually holding a spaceplane with large delta wings, even though even back then he was busy making rockets and missiles, and as far as I know never got far in designing a spaceplane.

I wonder if he just did that to capture the public's imagination, since those wings were so huge that you'd think even then they would have obviously been inappropriate.

In any case, I think these spaceplane ideas have stuck in a lot of folks minds. PBS did a special about 10 years ago that argued that in the 1950s, most folks expected we would reach space through continued progress with X-plane vehicles that flew faster and higher.

The X-15 began about the same time as Mercury, but X-plane research continued on in the right direction toward space applications, with the lifting bodies, but not too many folks were paying attention.

Since about 1990 when Langley promoted the HL-20, we've seen increased interest in lifting bodies, such as in the X-33 program and X-38 (which was a rather promising program, unfortunately cancelled). Now SpaceDev is reportedly developing its Dream Chaser, rather akin to the HL-20.

At least for manned flight, where g-loads and landing flexibility are very important, lifting bodies may represent the best compromise.

Thursday, November 30, 2006 9:58:00 AM  

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