Update on the week...

During the week I got my "paper" 4" otrag rocket to orbit.
This was a 2D rotating earth model including blow down pressure effects and atmospheric drag.
I assumed drag was the same as a sphere with the same frontal area as my otrag stack.
This was from 30deg latitude.

The classic otrag square 4:12:20, triangle otrag 3:12:20  and single tube last stage 1:6:12 all got to orbit. The single tube unit had the most margin.

I broke the trajectory into 2 segments for first and 2nd stage and 3 for third then did a brute force search of the space for optimum trajectory.... where my optimization fitness was horizontal velocity at 250Km with vertical velocity >=0.

I have a couple of other people doing modeling to "check my work" Ed Lebouthillier is one of the people helping me check my work with performance sims.  He put together the following picture...

I also reopened a discussion with the FAA on what it takes to do part 101 launches offshore...
and got a really favorable answer. On their request I'll publish more when the FAA resolves one remaining question. (Its really good news in any case)

Friday I got and assembled the pieces for a sunlight readable laptop... (pixel QI 10.1" screen and Samsung netbook) and swapped screens. Tested this in the Mojave on Saturday and it worked well.


Saturday I went out to FAR and almost finished cleaning up the old propellant.
This involved using a large "can opener" to open the tops of drums, removing the poly liner and getting the drums recycled.  The down side is that the can opener only works on about 50% of the drums. For the rest of the drums removal involved a  45 minutes, a cold chisel and a small sledge hammer... Did 9, have 5 left.

While I was at FAR I picked up a new carbon tube from John, with end reinforcement for better end cap retention at the desired 4" size. Will test this tank some time this week when I finish machining the end caps.

How to attach your plumbing to fabricated parts is always a challenge. With welded tanks we just welded on AN bungs.  But if your going for minimum weight welding really destroys the aluminum strength.  So the two remaining choices are machine AN fittings directly into the aluminum or put in an AN o-ring sealed port. Bought a port reaming tool and tried that Sunday night...
The tailstock on my lathe is a replacement and about 0.010" too high, with no adjustment.  So this caused the super rigid port reaming tool to chatter  screwed up the bore leading to bad threads... so I'll make another end cap tonight and probably do the port machining on the mill where I can indicate in center....

I may take the tailstock apart and try to machine off 0.010 between the base and the tail stock...
Need to set up to fully indicate the tailstock quill to see if its just too high or has parallel issues as well. (Quick run out test says parallel is ok and its just too high.)

Next up is to farther flesh out the detailed design of the paper rocket with respect to fill and drain, valves and gimbal actuators...

I'll try to post something at least once a week....


FAR has another event in two weeks, I may try to fly a PIKSI on my HPR to see how well it holds lock with with acceleration.

That's all for this week in unreasonable rocket land.