You can increase the performance of a rubber band system by using a tapered band and heating the band (below the point where it breaks down, of course). It's possible to get a rubber band to exceed Mach 1 (though very difficult to do so).Not worth it, of course. But fun.
Quote from: Robotbeat on 07/19/2014 10:03 pmYou can increase the performance of a rubber band system by using a tapered band and heating the band (below the point where it breaks down, of course). It's possible to get a rubber band to exceed Mach 1 (though very difficult to do so).Not worth it, of course. But fun.Now that I did not expect...Definitely one for the scrapbook of surprising physical phenomena. I admit I've a fondness for cheap launch assist systems. I'd not really considered them before. All of which is by way of observing that the end goal should be much more important than how the various entrants get there, since it's the only one that matters.
I suppose I should clarify... I believe it is /possible/ to break Mach 1 (with part of the band) with an extremely tapered band heated to its disintegration temperature, though I have not done it myself (with an extreme enough taper, I don't see why it couldn't technically be done, especially with some clever restraint mechanism). There have been some reports of 890 fps slingshot records, though they may be anomalous. 500fps projectiles with unheated bands is not unheard of.
Anyway, sorry. Off-topic and pointless.
Quote from: Robotbeat on 07/22/2014 04:10 amI suppose I should clarify... I believe it is /possible/ to break Mach 1 (with part of the band) with an extremely tapered band heated to its disintegration temperature, though I have not done it myself (with an extreme enough taper, I don't see why it couldn't technically be done, especially with some clever restraint mechanism). There have been some reports of 890 fps slingshot records, though they may be anomalous. 500fps projectiles with unheated bands is not unheard of.Hmm. Definitely a corner case then. QuoteAnyway, sorry. Off-topic and pointless.Agreed. Still one for the scrapbook. Personally I am looking forward to seeing how the various entrants will handle the heat problem. One of the things that wrong footed the entrants to the X15 competition was that they did not realizes the USAF wanted an aircraft that could soak at the full Mach speed, as part of the experimental regime.I don't think DARPA is calling for that capability, although M10 is well above any reusable vehicles operating range. X15 tried spray on ablator but that was a royal PITA to apply and strip off.
Quote from: john smith 19 on 07/16/2014 06:22 amInteresting point. So reusable VTVL 1st stage and expendable 2nd?Yeah. All the XS-1 contracts are focused on TSTO designs wiht reusable first stages with expendable 2nd stages, and I'm 95% sure Masten is going for a VTVL first stage for this effort. I mean, they could surprise us all, but I doubt it.
Interesting point. So reusable VTVL 1st stage and expendable 2nd?
QuoteThat's what I'm hoping. My instinct is it might be the combination of payload size and speed that makes it impossible to close.That said would it be DARPA if the requirements weren't almost impossible to be met? Hopefully they're open to creative interpretations of their requirements. For instance if the Mach 10 requirement is only on one flight, and isn't the staging velocity for a 3-5klb to LEO upper stage but just the max speed a first stage can get to with a small or non-existant upper stage, it might work. Especially if there's no requirement for the vehicle to hit Mach 10 inside the atmosphere--for instance if you could get up to Mach 10, release a small payload, then do a boostback that slows you to something reasonable before you hit the thick part of the atmosphere, that might make it more realistic as well. We shall see.
That's what I'm hoping. My instinct is it might be the combination of payload size and speed that makes it impossible to close.That said would it be DARPA if the requirements weren't almost impossible to be met?
Talking of the build materials guess you missed this that I already posted up thread.http://www.engadget.com/2014/07/11/darpa-materials-program/
Thanks for that.If they wanted to man this sort of vehicle wonder what sort of G loads the pilots would experience, comparable to the Shuttle or Dream Chaser.
http://masten.aero/2014/07/xs-1pr/
Company founder and CTO David Masten said, “....XS-1 is a great program to join with our vertical landing technology.”
Quote from: QuantumG@mastenspace yeah, what's with the wings dude? Getting religion from @XCOR?@QuantumG @mastenspace @XCOR actually, RTLS. But yesterday, optimizer removed the wings.
@mastenspace yeah, what's with the wings dude? Getting religion from @XCOR?
I guess having wings wouldn't preclude a vehicle from landing vertically, but aren't wings mainly for re-entry and fly back?...the extra weight seems like a loss, unless I'm missing something.
Reposting the picture for posterity. Mostly to confuse them as why a vehicle with the word "Masten" written on it has WINGS.
Apparently the Masten guys called them "Fings" instead of wings. It was still meant to take off and land vertically. I'm glad though that the optimization analysis has the "fings" going away again--they look kind of goofy on a VTVL bird.