Masten Space Systems does first hold-down firings with X-prize vehicle

[meiza]

Only one engine so far and no hinging* yet but it looks smoooooth!
There are youtube videos of course.

http://masten-space.com/blog/?p=94
http://masten-space.com/blog/?p=95

I think this is one significant milestone. Next big one will be firing and moving all engines and then of course integrating the computer and doing tethered flights.

(* hinging = 1D gimballing)

[braddock]

That looks nice!  Congrats to Jon and the other Masten folks!

[jongoff]

Thanks Meiza!

However it's probably worth mentioning that XA-0.1 is actually not our X-Prize vehicle.  It is a first-gen demonstrator.  If we go for Level One it will probably be with our 2nd generation vehicle (which has much better mass ratio).  

~Jon

[meiza]

Oh yeah, I actually read the chart today, the heavy chassis and the aluminium tanks limit this one's hover time to below 90 seconds. It seems really heavy even if it's so small!
Curiously the next one that is similar but has a lighter frame and carbon fibre tanks, you don't list any weights, it'd be intriguing knowing the empty mass.

[jongoff]

Meiza,

Oh yeah, I actually read the chart today, the heavy chassis and the aluminium tanks limit this one's hover time to below 90 seconds. It seems really heavy even if it's so small!

Well, when we started vehicle development we had barely started testing our engines and we weren't sure how deeply we could throttle.  We're using a fixed pintle style injector, and while pintles are known for being ok for throttling, we didn't know how far we could push it, so we assumed 50% as a conservative guess at the bottom throttle, and designed a vehicle that used a similar architecture to what we thought our final vehicle would use, which implied 4 engines...with how high the thrust was on the engines, and how relatively small the tanks were, we intentionally made the thing extra heavy to make sure it'd be able to land!

It turns out we can throttle down to at lest 30% stably, and possibly as far as 25%, so it turns out we were way overconservative on that one.

Curiously the next one that is similar but has a lighter frame and carbon fibre tanks, you don't list any weights, it'd be intriguing knowing the empty mass.

Well, we've kind of got that vehicle on hold while we get XA-0.1 in the air and started into its paces.  No sense in rushing into a new vehicle before we've had chance to learn what we can from the current version.  Don't want to repeat mistakes if there are any we haven't caught yet.  Depending on how funding, testing, and component technology development goes, things for the next vehicle could go several different ways....

So, it may be a little bit before we can release more info on future vehicles.  Sorry.

~Jonathan Goff
  Masten Space Systems

[braddock]

I've been curious having read so many of the Armadillo updates...those guys seem to burn through a new engine design every week.  You guys appear to have a pretty stable engine, with not too much word of burning injector plates and hard starts.  Is it just that we don't hear as much about the harsh learning curve from Masten, or are you guys doing something different?

[jongoff]

Braddock,

I've been curious having read so many of the Armadillo updates...those guys seem to burn through a new engine design every week.  You guys appear to have a pretty stable engine, with not too much word of burning injector plates and hard starts.  Is it just that we don't hear as much about the harsh learning curve from Masten, or are you guys doing something different?

To be fair to our friends at Armadillo, we've had our fair share of "learning experiences" as well over the past year and a half.  We have even mentioned several of them on the blog (such as our hard start last August, and some nozzle damage we had this last summer, and on a few of our heat sink engine nozzles).  Overall though, I think that there is at least some difference in methodology between the two groups, and we try to learn from each other whereever possible.

At MSS, we don't have inhouse machining capabilities (yet), have to pay salaries, and have far less money available than John's team.  So we tend to try and be a bit more methodical.  We did a bit of background literature research and decided to try a combination of approaches that have been succesful in the past for different big aerospace and alt.space groups (like the Chamber-Saddle-Jacket design used by XCOR and the Swiss Propulsion Lab, pintle injectors like used by TRW/Northrup and SpaceX, Copper thrust chamber liners like used by most larger regen-cooled engines, etc).  That way we knew that we were probably biting off a solvable problem.  We then just went about things from there with a good mix of experimentation, modeling, analysis, and engineering.  I think our more methodical approach shows when you consider that the only regen engine we've designed that didn't work was due to a CAD modeling error on my part.

The engines aren't quite so solid as I would like them, but they're finally getting close.  They're good enough to fly the vehicle on, have excellent performance, and are mostly quite robust.  I'm a bit of a perfectionist though, and I don't consider the engine done until I'd feel safe flying on a vehicle powered by it.

~Jon