Meeting #317

Attending: Dave W, Michael W, Kevin B, Dan S
Call to Order: 8:29 p.m., June 14, 2007

Dave W mentioned that the last of the freeze wheel parts were now in. He’s not sure where he will be able to work on them, but they are in. He talked about using the freeze wheel to draw off crystals and then heat then just until they thaw to get the concentration right. Kevin B mentioned that he had a copy of the patent used for commercial production units. It consisted of a cone that would freeze out crystals and allow them to fall down the center of the cylinder. There were coils of aluminum tubing in the cone to cool it down. If we added 1/2” swaglok fittings it would be simple to set up.

Kevin mentioned that the high density switch (from 85% to near 100%) comes in a very short distance – about 1 mm! They would put a spigot at the bottom to drain off the HTP, allowing almost continuous.

Dave W mentioned that his freeze unit should produce 5-10 K BTU/hr at about -40℃.

Kevin B mentioned that he has a stainless steel heat exchanger that he picked up at the local swap meet. He also had found (a while back) a monograph on “H₂O₂ Production Technology” at the San Jose State University Library. He was going to see if he could locate it, but it was likely in a box somewhere as they would be moving soon.

It was mentioned that DMez is available, but that QBane is too expensive to use for rocket fuel. It gets a few seconds better ISP than methane but is not cost effective.

The P.O.G.O. engines were discussed at it was pointed out they may be too short and fat for the catalyst samples Dave W had (17 mm diameter disks). These are a sheet mesh with ceramic coated with platinum. They were sample he got recently and were the same as our Swedish friend was having made. Kevin B mentioned that they may fit his 10 lb. engine. Dan had 4 sets of 70 samples and gave a few each to Kevin and Dan to try out. Dave W said they react very well with off the shelf 3% peroxide, which bodes well for reactivity at higher concentrations. There was no indication of delay as there was with silver screens. It was suspected the higher surface area was a key factor. They are composed of a two-layer system where a smooth, glazed surface is laid down and then a rough surface is boned to that.

Kevin’s Proposal:
Kevin B had brought copies of a proposal for Project LEVER, a low cost modular rocket propulsion system. The name is based on the Archimedes quote

“Give me a place to stand and a lever long enough and I will move the world.”

The basic concept is to use aluminum extrusions to modularize pressure fed rocket propulsion systems to take advantage of economies of scale and simply “bolt together” propulsions packages to use as boosters or to add on guidance and recovery systems and make full vehicles.

Much discussion followed. Kevin pointed out that the tanks (from Structural North America) were readily available and inexpensive. They had 600 psi burst ratings. He was planning on using the 12” x 54” tank as a sample base unit. There was also discussion as to whether or not they would be usable with alternative fuels for bi-propellent engines, such as ammonium nitrate disolved in water with 10% DMez. This would give a fuel with a density of 1.4 (to match the peroxide density).

Kevin stated (later in the meeting) that he hopes to have the first of his rockets ready by the end of the month. He may just fly it to a “ballistic return” – or he may add on a 10’ or 12’ parachute. With a bi-prop combination it should reach upwards of 100 km. Using similar diameter aluminum tubing with welded ends as pressure tanks the lines could be run down the spaces between the round tanks and the square frame.

He was asked about engine fabrication and there was discussion about using copper deposition and electro-forming technology to build up from an aluminum mandrel, which could then be disolved out with hydrochloric acid. Details of such a deposition system were discussed. and it was pointed out that “5 9s” pure (i.e. 99.999% pure) copper wire was sold as scrap at $3/lb.

There was also discussion of using wax channels when making a bi-prop engine and then dissolving the wax to leave passages for coolant on a regenerative engine. This led to a discussion of how thick the inner wall needed to be to keep the engine stable.

Dave W talked about doing some hypergolic fuel testing by soaking some of the disks he had in the fuel and the adding a drop of Hâ‚‚Oâ‚‚ to it.

Dan mentioned that he was still interested in building a 10” diameter Spike vehicle and was working on parts.He was encouraged to write up a proposal and bring it to the Board meeting.

There was no word back on following up with the TechShop folks about use of their space. Eric W was supposed to check but wasn’t at the meeting to give a report.

Adjourned: 9:46 p.m.

General Meeting #317