Masten and Armadillo Perform First VTVL Restarts 94
FleaPlus writes "Recently Masten Aerospace, winner of NASA's 2009 Lunar Lander Challenge, demonstrated using its Xombie vehicle the first-ever mid-flight restart of a VTVL (vertical-takeoff vertical-landing) rocket, a critical capability for the emerging suborbital/microgravity science and passenger markets (video from ground). Not to be outdone, John Carmack's Armadillo Aerospace (winner of the 2008 Lunar Lander Challenge) flew its Mod rocket to 2,000 feet (610m), deployed a drogue parachute, and then restarted the engine to land (multi-view video showing John Carmack at the controls)."
Just a step... (Score:3, Informative)
Re:Just a step... (Score:3, Informative)
These aren't designed to be orbital designs. The VTVL ships are indented for sub-orbital flight.
Re:"First VTVL Restarts" (Score:4, Informative)
Nope, first with the same engine (hence "restart"). LM landings used two different engines and stages for landing and taking off.
Re:"First VTVL Restarts" (Score:3, Informative)
Nope, first with the same engine (hence "restart"). LM landings used two different engines and stages for landing and taking off.
Thanks for the reminder about the separate ascent and descent stages on the Apollo LM. It's also worth noting that the Apollo LM used a hydrazine mix for fuel, which is quite handy if you want easy and reliable propellant (it spontaneously ignites when you mix it with the oxidizer), but is nasty and toxic, so you don't want to use it for an Earth-based launch where you have people nearby (or are planning on carrying people).
Re:Orbital Factories? (Score:4, Informative)
"Things tend to do that pesky burn up on re-entry thing."
Aerogels are ungodly insulating and resistant to heat. I've seen a piece just a few millimeters thick keep a crayon from melting with a blowtorch heating up the aerogel.
It's a type of glass, just like the ceramic heat shielding tiles used on space shuttles.
Re:Just a step... (Score:3, Informative)
Re:Orbital Factories? (Score:1, Informative)
http://www.airglass.se/
melts at 750C compared to 1650C reentry temps (for blunt nosed optimum aerodynamic designed vehicles like space shuttle)
http://en.wikipedia.org/wiki/Atmospheric_reentry
Also, the insulating properties of aeroglass is only slightly better than triple glazing (0.5W/m2K compared to 0.8W/m2K - see normal single pane glass at 6.2W/m2k).
Re:Fuel requirements? (Score:1, Informative)
It actually does make a big difference.
High altitude air launch advantages:
Lower air pressure at altitude means you can use higher expansion ratio vacuum optimised engines with greater exhaust velocity (ie more efficient), For example SpaceX's Merlin 1C engine ground fireable version gets 275kgs thrust for 1 sec from 1kg fuel (Isp=275s), in a vacuum it is 304s, but the vacuum optimised high expansion ratio engine gets 345s.
You do save significant aero drag losses.
You can save a lot of gravity losses that otherwise result from having to use a relatively low accelration rate to reduce dynamic pressure on the vehicle within the atmosphere.
Alltogether these effects can save anywhere up to 10% of your total deltaV requirements for launch - reducing it from perhaps 9km/s to 8km/s. That makes a huge difference to the relative weights of fuel and vehicle.