Lunar Lander Challenged

One small step for NASA, One giant leap for the X Prize

90-Second Hover

Armadillo Aerospace Lunar Lander Challenge team leader John Carmack updates the aRocket discussion group on progress:


This is a really big video that isn’t all that exciting:

There were two issues we were concerned about right after we did this flight:

The lox pressure dropped a lot more than the fuel pressure, causing a drastic mixture ratio change, and we wound up burning some stainless from the injector at the very end, probably because with the low lox pressure not bending the unlike impinging fuel elements straight down, we got a recirculating region that we don’t get at normal pressures.

There were some attitude oscillations towards the end of the flight.

We didn’t realize it until I looked at the side view video and telemetry back at the shop, but all the problem turned out to be was that the vehicle drifted enough that it was tugging on the tether bungee cords, which caused lots of firing of the lox side roll thrusters, depleting a lot of lox ullage pressure, and also caused the oscillations. If we had been flying without tethers, we wouldn’t have seen either issue.

There was a slight drift in the integrated velocity position versus the true position over 90 seconds of about two meters, which contributed to my not realizing the exact position of the vehicle and the tethers.

The second vehicle should be getting in the air next week, and we will be trying for the 180 second flights soon.

John Carmack

Written by spacefaring

September 25, 2006 at 11:10 am

Posted in lunar lander

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