Community > Forum > All other competitions > Starchaser should abandon suborbital space tourism.

Starchaser should abandon suborbital space tourism.

Posted by: virgair - Sat May 14, 2005 7:12 pm
Post new topic Reply to topic
 [ 34 posts ] 
Starchaser should abandon suborbital space tourism. 
Author Message
Space Station Member
Space Station Member
avatar
Joined: Thu Jan 27, 2005 12:34 am
Posts: 450
Post For SAFETY stay on the Earth   Posted on: Wed Jul 06, 2005 8:16 pm
skybum wrote:
you're implying unsafe practices on Scaled's part where in fact the exact opposite was true. The roll in the first X-Prize flight was thoroughly investigated. It was determined to be the result of a Pilot-Induced Oscillation, amplified via the rapidly-diminishing control authority that SS1 had as it ascended. While this roll-coupling and control authority issue is one that Rutan says he intends to improve in SS2, it was determined that it was in NO way a fatal flaw, and with proper pilot awareness, could be avoided.


I think it would be useful to stop imagining that we are involved in SAFE activities. I don’t fault Scaled for unreasonable or inappropriate procedures, but Melville didn’t take a parachute along for a seat cushion. The tail stall in unpowered tests was one of the worst possible aerodynamic failures, with recovery only due to the exceptional skill of the pilot. This problem was aggressively attacked and corrected. The landing damage (under ideal landing conditions and with an excellent and attentive pilot) reveled serious control system problems. Such an event has often caused the loss of an airframe (including one of the X-15 units). The doubts expressed by the second test pilot indicate that the control characteristics are peculiar and poorly simulated. That is what test pilots are for! The fact that an abort at that point was considered very risky (possibly regenerating the tail stall with an extreme aft CG not previously investigated) is a troubling situation. The roughly 120 degree roll (+ and -?) early in the June space flight mark the SS1 as a design with very poor roll stability. The lock up of the elevon on one side (with spontaneous = miraculous recovery?) was openly judged to threaten certain loss of the spacecraft, and possibly its pilot.

It is hard to evaluate comments on the sustained roll event, since Scaled is attempting to hide the existence of the third control system. This seriously complicates the control integration, but rockets can’t be powered out of the atmosphere WITHOUT THRUST VECTORING. Without such a system, tiny thrust vector errors will cause the craft to tumble! The cold gas jets used are far too weak to correct for the erratic thrust vector of this rocket motor. (The feedback from the mechanically linked thrust vectoring system is very visible in flight video.) A few recorded comments indicate that unexpected thrust errors – due to the eroding nozzle – are associated with the roll event. Attempting to hide this critical system (to preserve their distinctive competency) makes explanations of the roll event incomplete and probably incomprehensible. The roll itself was not a worry or danger to Melville, and may have been intentional, since this is one way to minimize thrust vector problems.

Overall, this looks like developmental testing of a high performance, aerospace vehicle, with all the dangers that includes. Depending on your world view – they were lucky or blessed by miracles – in recovering from several dangerous and potentially lethal anomalies. Good procedures and pilot skills of course minimized these events and maximized their potential to successfully recover. Excellent work!

But to imagine that this is a craft ready for commercial service is naive! Scaled is of course scaling up for the hard work of perfecting this vehicle (probably a factor of ten increase in investment). What worries me most is the apparent “ease” of this effort will mislead teams which are far less equipped to face the real difficulties and dangers!


Back to top
Profile WWW
Space Station Member
Space Station Member
avatar
Joined: Thu Jan 27, 2005 12:34 am
Posts: 450
Post Re: Starchaser should abandon suborbital space tourism.   Posted on: Thu Jul 14, 2005 10:06 pm
virgair wrote:
Starchaser's newly completed and tested 33,000Ib thrust CHURCHILL Mark3 rocket-motor can be CLUSTERED to launch a manned spacecraft into orbit.

Starchaser has some advantages


Your crystal ball seems to be working better than my computer! All the news that I can find ends with announcements that Starchaser has a welded shell which might conceivably become part of a big rocket motor, if and when they can get the remaining critical parts (the injector plate assembly). (One note mentioned that they did purchase the blank metal for the eventual fabrication of one such part). And if it works exactly as predicted. (The copious Armadillo reports are relevant to the clockwork succession of achievements likely in rocket development!) Some liquid fuel motors burn through, demonstrate weaknesses, or exhibit unstable, unreliable or inefficient combustion.

A few years ago, a very large volume of composite materials had the potential to become the spacecraft called X-33. But then it was tested: it is now scrap.

While I wish these team efforts well, it remains easy to overstate their status. Starchaser, as mentioned, does have advantages. Not necessarily its low “pro forma” cost – since costs are never more than guesses until a development project is done – but in the fact that its design is not limited to suborbital use. Plus the fact that the Brits who want be reenter the space age have one good team to get behind! And it is good to have them among the teams who haven’t given up.


Back to top
Profile WWW
Moon Mission Member
Moon Mission Member
User avatar
Joined: Mon Nov 01, 2004 6:15 pm
Posts: 1233
Location: London, England
Post    Posted on: Thu Jul 14, 2005 10:22 pm
I must admit that I thought they had tested their Mk3 Churchill engine by now but all I could find on their website was this rather old news release which says they will be unveiling it.

http://www.starchaser.co.uk/index.php?v ... led_110505

Perhaps I've managed to confuse this with the small LES engine they tested recently. :?

_________________
A journey of a thousand miles begins with a single step.


Back to top
Profile WWW
Moon Mission Member
Moon Mission Member
avatar
Joined: Tue Feb 10, 2004 2:56 am
Posts: 1104
Location: Georgia Tech, Atlanta, GA
Post    Posted on: Mon Jul 18, 2005 12:57 pm
Yeah, I thought the Churchill was tested, too....

_________________
American Institute of Aeronautics and Astronautics
Daniel Guggenheim School of Aerospace Engineering

In Memoriam...
Apollo I - Soyuz I - Soyuz XI - STS-51L - STS-107


Back to top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 34 posts ] 
 

Who is online 

Users browsing this forum: No registered users and 17 guests


© 2014 The International Space Fellowship, developed by Gabitasoft Interactive. All Rights Reserved.  Privacy Policy | Terms of Use