[AR] Re: Built another hovering rocket
- From: Jonathan Goff <jongoff@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Tue, 10 Feb 2015 21:30:25 -0700
Ben,
Congrats on getting another one in the air!
Out of curiosity, could you explain the logic behind the 13 motor
configuration? I mean, I guess it's somewhat similar to Centaur, which also
has one big central engine and something like 12 smaller engines for pitch,
yaw, and roll control. I guess in your case like Centaur's, they want 3DOF
attitude control capability even while the main engine is off?
But why not gimbal the main engine? My guess is the thruster size you need
for 3DOF attitude control during coasting is likely a lot smaller than what
you need to handle all pitch, yaw, and roll control with the main engine
fixed. And gimbals just aren't that hard.
Understandable if you can't answer on a public forum, but you piqued my
interest.
~Jon
On Tue, Feb 10, 2015 at 8:22 PM, Ben Brockert <wikkit@xxxxxxxxx> wrote:
> I was the propulsion/structural lead on another hovering rocket, this
> one for Moon Express:
>
> https://www.youtube.com/watch?v=QAMPD65dvIY
>
> Concept to first flight in a bit under four months. It was built to
> match MoonEx's planned control scheme and so has a slightly unusual
> architecture, with one large fixed engine in the center and twelve
> fixed thrusters at different downward angles on the outside. Center
> thruster is monoprop peroxide (FMC "90%" which is actually 86.6% now),
> outer are nitrogen cold gas.
>
> It won a $1M "terrestrial milestone prize" from the Google Lunar X
> Prize. Astrobotic also won a $1M prize doing flights on Masten's
> Xombie, so rockets I helped create have now won $3.15M of prizes. It
> is not lost on me that this is an extremely odd thing to make money
> at.
>
> It is a bummer that good peroxide is so hard to get or I expect we'd
> see a lot more peroxide rockets on AR. If anyone is curious I'll look
> up the pricing on the FMC stuff.
>
> Ben
>
>
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