Tuesday, February 26, 2008

Hardware, Rocket Hardware

If I learned any lesson from last years attempt its KISS keep it simple stupid.
A 4 engine vehicle with 39 valves is not going to fly reliably. Toward that end this years vehicle is going to be much simpler. Today I got a package...

The more I work on this stuff the smarter John Carmack gets... these are 6 5086 spun aluminum hemispheres from AMS industries.

They are 30" ID 0.1875 inch at the base 0.171 thick at the edges. 19 lbs each half. This should conservatively give me a burst pressure between 600 and 800 PSI. I'm shooting for 500, so I may lighten them a bit. The edge thinning is a lot less than AMS said it would be so I could have gone down a size in the thickness and saves some weight.

Given KISS what is the simplest system that will do the level 1 prize?
A Peroxide monoprop.
Everyone who works with peroxide spends inordinate time playing with cat packs. So I'm going to test a liquid catalyst like the Germans used 65 years ago. Using 85% peroxide I'm well under the melting temperature of 316 stainless so no cooling is needed I can just use a stainless chamber. I can also buy No clog spray nozzles in 316 from McMaster Carr and use off the shelf spray nozzles. The big question I have is with a liquid catalyst, what do I need to L* or chamber length? So I got a simple experiment I hope to run this weekend, its a long Stainless tube with 316 stainless pipe fittings welded in one end. In the pipe fittings I screw in off the shelf low clog spray nozzles and install thermocouples down the length of the tube to see what length is necessary to get maximum decomposition temperature.

Monday, February 18, 2008

Bittersweet day

My son and I spent the day cleaning out the garage in anticipation of getting back to rockets.
Part of this involved taking the carcass of the origional Unreasonable rocket to the aluminum scrap dealer. We both agree that a 4 engine vehicle is just too complex, but its still sad to take brackets, fittings and tanks one worked hundreds of hours on back to the scrap dealer.

Saturday, February 16, 2008

Progress and thoughts...

I flew the helicopter in attitude hold mode today.
It worked perfectly. the autopilot flys a lot better than I do. On flight #2 the commercial off the shelf RC regulator failed and the servos acted very erratic.I set it down with no damage. More debugging Sunday.

My son and I spent the day at FAR, we went out to clean up our storage space, work on the site and watch a large 5K liquid test firing. The work on the site is the real sexy part of rocket development. I spent my morning repairing the outhouse door jamb and installing godzilla's own door closer. Maybe the Mojave winds wont rip the outhouse door off, again.

After a full day of checkout the large test was a no light with a frozen LOX valve. We were not involved other than as spectators. My son has been working with some people doing peroxide rockets of various forms,and the grass on that side of the fence looks a lot greener.... Use cheap nitrogen for a presurant gas, all your valves and plumbing are at room temperature, dense, reasonably clean. Possibly auto igniting in bi-prop mode after decomposition.... hummm....

Monday, February 04, 2008

Quick Update

I've been very busy with "Other" mostly trying to catch up on work. I've been doing some work on the helicopter and I've flown it a few times, but no big news to report on that front. I've started testing with the DGPS and I've come to the conclusion that I need better antennas to make the RTK work. My one successful RTK test with the antennas on my roof took 46 minutes to resolve the integers, and then the solution was accurate to within 6" at 10Hz for 10 hours. The average RTK solution between the antennas was 20.02" with actual measured truth being 19.75". My son has come back down from the bay area to work on some rocket projects, both unreasonable and other..... I can't talk about "other" other than to say it is a paying gig. I'm glad to have him home.

I also find it frustrating that its sunny all week when I can't fly, then it rains all weekend where I can't fly.(Actually it stopped raining during the super bowl and I choose to watch that) This week is not going to be "unreasonably " productive as I have a lot of stuff going on.