Friday, August 29, 2014

TR-1 Rocket Motor Casing

Completed Motor Casing:


With the casing now completed I will focus on completeing the bulkhead and with that I will have all of the motor componets.  Then I'll turn my attention to making some simple casting tools for the 4" diamter grain segments.  I'm also gathering a list of supplies that I'm hoping to order soon including screws, o-rings, Sorbitol, casting tubes, and a few other misc. bits.

Wednesday, August 27, 2014

Boosted Darts

I've been a fan of the boosted dart concept for a long time.  My first introduction to the concept was the RRS's boosted dart project that was launched in 1996. I hadn't begun my journey into the world of amateur rocketry yet but just six years after that launch and a year or so of building my own motors, I found myself at the RRS site in the Mojave desert with what I thought was a big rocket, a scratch built rocket that was powered by my version of Chuck Knights J-class sugar motor fabricated from PVC pipe.  That rocket flew and was recovered successfully. Later that same day I witnessed a firing of a motor that dwarfed anything I had done or even thought was in the realm of what an amateur could do. It was a slightly larger version of the booster that the RRS guys had launched at Blackrock.  It was a spectacular firing that unfortunately cato'd.  It made a HUGE impact on me never the less and as I began researching the old sounding rockets of the 50's and 60's I came across the Loki Dart and became even more intrigued by the boosted dart concept.  The amazing thing about the boosted dart concept is that the dart typically coasts most of the way to apogee.  In the case of the RRS, the booster reached an apogee of around 3 miles while the dart coasted to approximately 50 miles.  It's kind of like hitting a baseball. Think about it, a baseball completely changes direction when the ball is hit by the bat and yet within those few milliseconds that it is contact with the bat it gets everything it needs to "coast" into the stands. I've been slowly getting back to rocketry lately and have been thinking about a high altitude attempt. The boosted dart concept seems like the way to go.  I don't currently have the ability to build something the size of  the RRS boosted dart project, but that's where the little Loki dart comes in. The Loki dart from the 50's had a max altitude around 34 miles. The booster for the Loki is a relatively tiny 3" in diameter and produced a bit over 2000lbs of thrust for a little under 2 seconds.  Now those numbers seem much more doable.  I should be able to fabricate a motor up to 7" in diameter, which is good since I'm working with a lower ISP propellant I'll need a larger booster than the Loki used to get similar performance.  The TR-1 motor that Theo and I are currently constructing has the same total thrust as the Loki booster. That motor isn't currently geared towards being a booster but with some relatively minor design changes it could be a decent booster for a boosted dart. I'm planning to fly this motor as a boosted dart to get some experience. If that goes well, the plan is to build a  larger 6" diameter optimized booster and see just how high we can go.

You can find a PDF of the RRS booster dart project on the RASAero site here.

Monday, August 25, 2014

TR-1 Rocket Motor Update

Started work on the after what has turned out to be far too long of a and such getting in the way.  We got the motor casing cut to length, ends trued, and screw locations drilled.  Theo and I are hoping to fire this motor mid September and fly before the end of the year.  Pending a successful static firing the plan is to use this motor as a booster for a boosted dart configuration.  More on that later...

Monday, June 17, 2013


I finished the modifications to the Sugar Shot to Space's DSS TM-3 motor this weekend.  It was particularly tough machining through screw holes.  The open spaces created a hammering effect that subjected the tool and lathe to quite a beating.  I wonder if filling the holes with epoxy would have helped.  Once the adapter ring arrives I will make sure the two pieces fit together and that they fit the motor casing.  For now, I'm back to work on the TR-1 motor.

Thursday, June 13, 2013


I'm making good progress on the nozzle, but it's slow going.  I'm about halfway through the biggest modification which is cutting a relief that the adapter ring will fit into.  The area that I'm cutting away has the screw holes in it and cutting through that section really hammers the tool.  The other mods should be simple by comparison.

Wednesday, June 12, 2013


I've started refurbishment/modification of the nozzle for the upcoming TM-3 test.  Having seen the force with which this nozzle bounced across the Mojave desert last year, it's in remarkable condition.  I started by cutting off the eight screws which held on the divergent extension.   The threads we so messed up that cutting them off was the easiest way to go.  The mods are pretty simple; removing some material from the shoulder to accommodate an adapter will take the most time.  I have it in the lathe now and hope to finish it this weekend. Marco clearly did a great job machining this nozzle.  I'm sure it was not an easy task and it would be awesome to finally get a solid firing with this nozzle.

Sunday, June 9, 2013


I  made good progress on the TR-1 nozzle this weekend.   The two pieces fit together nicely.  I'm still tempted to take some weight out of the nozzle, I think I could get a nearly half a pound of weight out of it. I'll probably hold off until after the initial static test before trying to reduce the nozzle mass.  I'm currently making some modifications to the DSS motor nozzle for the Sugar Shot to Space project.  Once that's completed, I'll finish the TR- 1 nozzle and get to work on the rest of the motor.