Thursday, August 7, 2008

The Wind at Dawn Flight Simulations

When we set out to enter the Lunar Lander Challenge, we had to do a lot of work to design The Wind at Dawn. There was a whole month spent working out some of the really basic equations and then translating them into some simulations of the flight based on changing mass, throttling, thrust profiles, wind, and several other factors. It was interesting work because it was all tied together. If you consume propellant, the amount of thrust needed to flight at a given height decreases which causes throttling changes which changes the amount of propellant that is to be used. etc. In the end, we had a series of numbers for given time frame snapshots. These were heights, lateral displacements, throttling requirements, thrust, etc. We took these to the ever talented Scott E of Coherent Lighthouse and his nice little IRIX cluster. He did a crazy bang up job and produced the following visualizations of the event.

The first visualization is if you had a 'travel camera' that was back about 3m or so that would allow you to focus on the vehicle as it lifted off and keep altitudal pace with it. Unfortunately, the viz machines choked part way through and we had a deadline, so the video is incomplete. Since the flight isn't really that interesting from this POV, we asked if he'd just give us what he had.

The second visualization is from the point of view of an observer 250m away from the flight path of The Wind at Dawn. This video shows the whole flight.

Let's say that we strongly recommend the work of Scott Elyard. He's a hard worker, able to get work done on short notice, and a good guy all around.


WizWom said...

Northrop Grummann does understand that a vehicle that can hover in earth's 1G field is way overpowered in rocket capacity for landing and taking off from the 1/6th G on the moon?

Team Phoenicia said...

Hello wizwom.

You have a few misconceptions there. Allow us to rectify that!

First off, the Northrop Grumman Lunar Lander Challenge is not run for and by NorGrum. It's actually run by the X Prize Foundation for NASA. As for why NorGrum is involved at all in the name, may I suggest the X Prize Foundation's FAQ?

There's also a reason why they selected 180 seconds in a 1 G field for the second level challenge. It's not so they can develop a rocket to hover on the Moon - however most designs probably easily could! - but rather because 180 seconds of hovering in a 1 G field neatly matches up with the Delta-V needed to transit from the lunar surface to orbit.

Hope this helps!

WizWom said...

I understood the delta-V requirement for 180s @ 1G and lunar orbit to lunar surface (sortof - depends on the lunar orbit you choose).

It's just a 1G rocket will be logs heavier than a 1/6G rocket; in fact there are technologies and fuel suitable for 1/3G with higher SI but that you could not use in a 1G rocket.

Oh, well, it will still be an interesting demonstration.