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Saturday night we fired MHD generator test number 27. This was the our first with a composite motor, an Econjet F-20.

We incorporated the structural lessons from test 26m segmented top plate and forward electrode plate retention wires. The motor was double of thrust from test 26. We were anxious to see if it would all hold together. We need it to be able to handle a “J” class motor to be used on the desktop quad engine.  The structure held find but the cathode was completely eaten through. The composite motor also left a hard non conducting coating on the electrodes.

The firing went well, but the test failed. Just before the end of the run the datalogger failed. Not a bit recorded. Grrrrrrr. Time for new dataloggers.

We did get some good info on the structural modification. The segmented plate showed no cracking at all. The baked epoxy plate had the epoxy cut out right along the flow line then cracked clean through. The detachable main unit stayed put during the firing.

Parts are curing in the oven for MHD generator test number 26. There are several changes in the structure of the unit. The base plate is made of nine segments instead of a single  ceramic plate. This is an attempt to avoid thermal cracking by allowing expansion. The upper plate is porcelain coated with two baked on epoxy layers. The epoxy will ablate and throw some of the heat out. In the new design the ceramic core of the unit can now be removed from the motor mount backbone. This will make the unit a lot easier to repair. The test before was a breakthrough for stable power output and measurement. That test was with a “C” motor. This test will be with an “E”, 4X the thrust.

We’re about an hour from the firing.

This was Away 24 back in 2004.

This winter has reminded me of the Away 5 mission. This was back in January 2000.

After all the repair we thought a shakedown was in order.

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Neither rain, nor snow, nor freezing cold shop…  or some thing like that. In spite of the icicles on our chins we built, glued and made noise today. We are going to experiment with several different material designs for the next round of MHD tests. We made segmented plates and baked epoxy onto porcelain for the next round. We finished off the three fan units in the crew module mock up. We got to hear first hand how fan noise is a critical problem in life support systems, even with very quite fans. All the repair are complete with the chase plane so we pulled her outside to see if we could fired her up. With a few pull the engine roared to life.  She feels like shes wants to fly.

Drew baking and Anthony cutting.

The top intake fan in the mock up.

Another step complete for the chase plane.

Before and After

I was trying to avoid this one. We need to build our own supersonic high altitude wind tunnel. I was hoping to do the next wave of research in the live environment, test runs using rockoons with the test articles on the nose.  However the number of iteration we need to do is just driving the timeline too long.  To keep in the schedule we’ll need to be able to run the bulk of the tests at the shop. We’ll then followup with the rockoon flights.

The wind tunnel needs to run at mach 3 for up to five seconds at a pressure equal to 200,000 feet. The test segment needs to be non conductive. The test section needs to be about 2 inches across. There are tunnels out there that fit the requirement but rental cost is too high.

The rough estimate is about $3500. We won’t be able to start building it until Tandem flies. There just isn’t room for it till then. That’s ok. It will take some time to get the design complete and raise the funds. I expect construction to start in October with the first runs to take place next winter.

For the past three days I’ve had my other hat on. We built this 4000 bag wall to protect a house that sits two hundred feet from the creek.  The creek had risen two feet over the bank in the storms over Christmas.

At 100,000 pounds this is the heaviest thing I’ve ever made.

Check out our sand bag site here.