JP Aerospace Blog

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.