Dream Chaser

Author
Discussion

Eric Mc

Original Poster:

121,958 posts

265 months

Tuesday 20th August 2013
quotequote all
Interesting video on recent taxi trials of this new reusable spacecraft.

http://www.youtube.com/watch?feature=player_detail...

I just wish it had a better name.

AshVX220

5,929 posts

190 months

Tuesday 20th August 2013
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Looks very small. I guess it's only going to be used to change crews on the ISS?

Also, no nose wheel, interesting.

Does look very cool though. smile

Eric Mc

Original Poster:

121,958 posts

265 months

Tuesday 20th August 2013
quotequote all
Yep - crew transfer vehicle.

Kind of what NASA originally had in mind when they started their lifting body programme in the 1960s. The Space Shuttle only ended up as big as it did when NASA's original plans for a permanently maned space station were axed and the US Air Force insisted that the original design be enlarged to accommodate DoD payloads.

AshVX220

5,929 posts

190 months

Tuesday 20th August 2013
quotequote all
It's lucky they didn increase the shuttle size for the DoD, or the ISS may have been too expensive and therefore less appetising to build.

Eric Mc

Original Poster:

121,958 posts

265 months

Tuesday 20th August 2013
quotequote all
If they hadn't built the Shuttle so big - and given it wings (another DoD requirement) it would not have cost so much and would have been a far more robust and more reusable piece of kit.

If the Shuttle development costs had been saved, they could have kept the Saturn V line open and used it to launch an ISS sized structure in two launches 30 years earlier than they actually did.

I bet firing off a couple of Saturn Vs over maybe a few months would have been a LOT cheaper than the 12/13 years it took to assemble the current ISS to the size it is now.

I think now that the Shuttle is gone, at long last a PROPER series of REALLY practical manned spacecraft are being devised that will do the job of the Shuttle as far as low earth orbit spaceflight is concerned. And they'll be hopefully safer too.

XM5ER

5,091 posts

248 months

Tuesday 20th August 2013
quotequote all
Isnt that what Steve Austin crashed in the opening sequence of the Six Million Dollar Man
http://www.youtube.com/watch?v=HoLs0V8T5AA


Eric Mc

Original Poster:

121,958 posts

265 months

Tuesday 20th August 2013
quotequote all
Not quite.

As I mentioned earlier, in the 1960s, NASA commissioned a number of studies into various "lifting body" designs to explore the feasibility of using a wingless aircraft to make a controlled landing on a runway.
The theory behind the shape was that the best shape for re-entry from space was a "blunt body" - such as the Apollo Command Module. But a blunt body gave virtually no aerodynamic control over the craft once it had slowed down in the earth's atmosphere. That is why parachutes were needed for a gentle landing.

A lifting body combined the re-entry requirements of a blunt body with some aerodynamic flight control.

It was not obvious what shapes gave the best lift so a number of experimental craft were tested between 1963 and 1975 to try out different configurations.

In the end, because of lack of funding from congress for their original Shuttle ideas, NASA had to team up with the US Department of Defense.
The DoD did not like the simple lifting body because once the de-orbit began, it had limited glide capablity either side of the re-entry track. The military wanted greater "cross range" for their Shuttle and insisted on proper wings.

We are finally seeing some of that 50 year old experimentation result in a workable, spacefaring manned lifting body.

Russian Rocket

872 posts

236 months

Tuesday 20th August 2013
quotequote all
there was a documentry few years ago after the second shuttle crash basically saying it was a disaster

military want big payload so it was lot bigger than orinaly planned then needed external fuel tank, then solid rocket boosters.... all next to an incredibaly fragile heat shield

it was supposed to be cheap with a big fleet and a launch every couple weeks

if nasa had continued to develop the saturn rocket (like russians did with their rocket) they would have done far more for a lot less

Edited by Russian Rocket on Tuesday 20th August 17:54

Eric Mc

Original Poster:

121,958 posts

265 months

Tuesday 20th August 2013
quotequote all
Correct essentially.

Throwing away the Saturn V and the F1 rocket was a massive mistake.

Caruso

7,432 posts

256 months

Tuesday 20th August 2013
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Not so different a concept from the X-20 DynaSoar from 1962

http://www.youtube.com/watch?v=8Bn5A0oNpuM

Eric Mc

Original Poster:

121,958 posts

265 months

Wednesday 21st August 2013
quotequote all
Not really.

The Dyna-Soar was not really a lifting body. In fact, the Dyna-Soar design was finalised before any real data had been obtained from the lifting body research programme. The Dyna-Soar was more of a winged delta - a bit like the final Shuttle design in fact.

An interesting aspect was the shift from winged delta (X-20 Dyna-Soar) to lifting body and back to winged delta (Space Shuttle). And the reason behind the shift is that the US Air Force did not like lifting bodies because they weren't capable of changing their landing destination easily once the de-orbit burn had been conducted and re-entry begun.

Dyna-Soar was a US Air Force programme - hence the winged delta shape. Once the Air Force had more or less hijacked NASA's Space Shuttle, they insisted that the Space Shuttle too become a winged delta.

AshVX220

5,929 posts

190 months

Wednesday 21st August 2013
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Thanks for the posts Eric, everyday's a school day. smile

Eric Mc

Original Poster:

121,958 posts

265 months

Wednesday 21st August 2013
quotequote all
I have doubts as to whether the Dyna-Soar idea would actually have worked.

It was more of a political programme rather than a true technical programme anyway.

The USAF were very miffed (in fact, downright livid) that the manned space programme had NOT been passed to them. They very much (and still do to some extent) resented the very existence of NASA's manned programmes.

Throughout the 1960s and 70s they lobbied like anything to set up their own separate manned programme independent of NASA's. Initially they looked at an orbital version of the X-15. This then morphed into the X-20.

Here's one concept for launching an orbital X-15 using a Saturn I derived launcher.



Here's a picture of what an X-20 Dyna -Soar launch might have looked like - using various derivations of teh Titan ICBM -




I think it was pretty obvious very early on that the Dyna-Soar was a dead duck so the project was scrapped in 1964, being replaced by the Manned Orbiting Laboratory (MOL). MOL was a manned surveillance station which, like the Dyna-Soar, would be lifted into orbit on to of the Titan 3. It also used the already in development Gemini space capsule as the actual spacecraft.




The USAF were not keen on relying on the US Navy to fish them out of the ocean after each flight so they spent a lot of time and effort into designing various types of Rogallo wing and parawing systems to allow the Gemini to glide into to land on a desert runway.




They could never get the canopies to unfurl satisfactorily so that idea was abandoned.
In 1969, MOL itself was canned.

Eventually, the USAF got its way by muscling in on NASA's Shuttle and basically respecifying the whole project to suit their perceived needs - and thereby more or less ruining it and sabotaging manned space exploration for half a century.


annodomini2

6,861 posts

251 months

Wednesday 21st August 2013
quotequote all
Russian Rocket said:
there was a documentry few years ago after the second shuttle crash basically saying it was a disaster

military want big payload so it was lot bigger than orinaly planned then needed external fuel tank, then solid rocket boosters.... all next to an incredibaly fragile heat shield

it was supposed to be cheap with a big fleet and a launch every couple weeks

if nasa had continued to develop the saturn rocket (like russians did with their rocket) they would have done far more for a lot less

Edited by Russian Rocket on Tuesday 20th August 17:54
The heat shield was fragile due to another Airforce requirement, much steeper re-entry profile.

Basically if one of their shuttles (which they never bought) came under attack they wanted it to have a short a time as possible from orbit to ground.

This required the heat shield to be able to withstand much higher temperatures than NASA needed.

But the Airforce were paying for most of the development.

Eric Mc

Original Poster:

121,958 posts

265 months

Wednesday 21st August 2013
quotequote all
I'm not sure about the steeper angle of descent to be honest.

The REALLY important Air Force requirements were

i) size - it had to be big enough to hold a Big Bird or Keyhole spy satellite

ii) wings - it had to have a much greater cross range glide potential for Air Force use compared to what NASA needed.

Why did the Air Force need a better glider than NASA?

Because they envisaged launching the Shuttle on polar orbital missions - necessary for the Big Bird and Keyhole satellite deployment missions.

If launched in a polar orbit, the world rotates under the Shuttle by 15 degrees for every orbit. The Air Force wanted to be able to launch a Shuttle with only a few hours notice and do a one orbit mission, re-entering immediately after that one orbit. Of course, in a mission like that, as the Shuttle came back down, the launch site - and landing site, of course (Vandenberg Air Force Base) would have rotated 1,500 miles to the east. The USAF wanted the Shuttle to be able to bank and turn off the original re-entry track by that 1,500 miles to get back to Vandenberg.

NASA had no need of such a capability as NONE of their Shuttle flights would be polar orbital flights and none of their flights would be quick "pop-up and re-enter" type missions.

It was the wings that made the Shuttle's re-entry so hot and it was the wings that needed protecting - especially the leading edges. A lifting body would not have had a leading edge to worry about - so you could not have had a Columbia type accident.

Of course, this was all specified in 1972 when it was anticipated that Shuttles could be got ready for a mission at short notice and that individual orbiters could be "turned around" within 2 weeks of completing a previous flight.

As we all know, the Shuttle system was completely incapable of meeting anything like such a schedule of frequent flights.

In 1972, it was stated that the Shuttle fleet would complete 2,000 flights by 1990. The fleet managed just over 130 flights by 2011 - and killed two crews.

Russian Rocket

872 posts

236 months

Thursday 22nd August 2013
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I remember seeing a documetary prior to the first launch about the TPS tiles and how they might repair them in orbit if needed. they didnt seem to have a satisfactory solution.

then when they launched the problem seemed to go away and there wasnt even the need to inspect it.

I was quite young at the time I remember missing a chemistry class so we could all watch the launch

Eric Mc

Original Poster:

121,958 posts

265 months

Thursday 22nd August 2013
quotequote all
The problem never went way. They just ignored it until they convinced themselves it wasn't a problem.

And we know what happened eventually.

MartG

20,666 posts

204 months

Monday 6th November 2017
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Approach and landing test ALT-2 due soon

https://www.nasaspaceflight.com/2017/11/dream-chas...

Eric Mc

Original Poster:

121,958 posts

265 months

Monday 6th November 2017
quotequote all
Thanks for resurrecting the thread - which I'd forgotten about. Looking forward to Dream Chaser flying again.

MartG

20,666 posts

204 months

Thursday 9th November 2017
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ALT-2 set for next Tuesday

SNC have also signed a contract to launch Dream Chaser on an Atlas V

http://www.waaytv.com/content/news/Sierra-Nevada-s...