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Catalyst delayed again

September 13, 2003 notes

 

Much to our dismay, our big order of platinum catalyst has been delayed again, so we didn’t get to do any engine testing this week.  They say it is due to ship next Thursday now.  Also no update on our 90% peroxide supply.

 

I spent Thursday at White Sands Missile Range discussing our flight operations.  WSMR is a spectacular location for flying rockets, but they are a military facility, and they aren’t really sure they want to be involved with commercial manned rocket ships.  We have some good supporters there, but they consider flying something before the end of 2004 a “very aggressive schedule” just to get all the paperwork done.  Cost may also be an issue – a test taking full advantage of all the range facilities, like tracking, telemetry, flight termination, and other services, can cost $180,000 per test flight.  That is a lot more than our entire vehicle costs, so we clearly aren’t interested at that level.  Our position is that all we want from them is a clear range, and we will handle everything else.  We need to convince them that our vehicle absolutely, positively cannot leave the range boundaries under any failure condition, so we can fly without real time monitoring and a flight termination system.  Somewhat surprisingly, the dominant factor by far is drift under the main parachute if a series of failures causes the vehicle to apogee at 100,000’ and deploy the main parachute there.  High winds can cause it to drift a long way by the time it gets to the ground.

 

I think I finally found The Right Thing for absorbing shock loads on the hover test of our big vehicle.  They are called “snatch straps”, and are used for recovering stuck off road vehicles.  Unlike a normal tow strap, where you bring the line up taught and slowly apply load, these are designed to actually have the pulling vehicle take a run at it with a slack strap, building up a lot of energy.  Normal nylon straps stretch about 10% at their breaking point.  Snatch straps are woven so they stretch 20% at half their breaking point, and are designed to do that many times.  We are going to use these for both the hanging and ground restraint strap on the big vehicle hover test.  The ground restraint will be enclosed in a tubular woven ceramic insulation sleeve to protect it from engine heat.  Really cheap, too – a JC Whitney item.

 

We have started using ¼” stainless cable for some things recently, like the lines going through the top of the cabin wall to connect to the snatch strap shackle, and the line to the drogue on the bottom of the big vehicle.  This is as big as we can go without needing a hydraulic crimper, and gives us 5700 to 9000 pounds of strength, depending on the cable configuration.  Working with chain and shackles is usually a lot more convenient than wire rope, but the wire rope is a lot lighter for a given amount of strength.  When we fly the big vehicle with the big engines, we are going to need significantly more strength in the drogue line, so we may wind up going to an insulated synthetic (spectra / Kevlar / etc) rope to save weight over a huge stainless cable.  We did figure out that if you cut the cable with a welder and bead the end a bit, it is a lot easier to work with than if you manually cut it.

 

Our big piloted solenoid valve, a ¾” 6242 series from Snap Tite, arrived this week, and we built a big pneumatic drogue launch tube to test it.  Results were better than expected.  The valve is more compact than I thought it would be, and it has nice positive opening and closing.  Our previous experience with piloted solenoids from a different manufacturer was not so good, but I like this model.  Our small vehicle uses the giant 30 amp direct acting NOS solenoid to dump a 600 psi tank into its small drogue tube.  We had found that a good O-ringed piston was necessary to get this kicked out.  With the big piloted solenoid (that only draws 1.5 amps), we were able to punt our big parachute all the way across the room even without an O-ringed piston, at only 250 psi tank pressure.  We had some difficulty dealing with 50’ of ¼” stainless cable connected to the drogue, though.  It can’t coil in the 4” diameter drogue tube, and various methods of external coiling are difficult to both guarantee deployment when you want, but not do anything bad under high flight wind loads before deployment.  We may wind up just using a larger diameter tube.

http://media.armadilloaerospace.com/2003_09_13/gasGun.jpg

 

We did some more work on our Russian space suit now that the blown zipper has been repaired.  We got an excellent book on the topic: http://www.amazon.com/exec/obidos/tg/detail/-/185233732X/qid=1063573608/sr=8-1/ref=sr_8_1/002-0650100-0153661?v=glance&s=books&n=507846 which gave us some important information.  The likely reason we blew the bad zipper was that there was a restraint strap missing on our suit, which put a lot more stress on the zippers than they should have held.  We fabricated our own clasp, which seems to work well.  We closed up two more notable leaks through various fittings on the suit, and it is holding air a lot better, although it takes more than 2 scfm of flow to get up to operating pressure.  It looks like a couple of the other zippers were weakened when we popped the bad one, so we are going to get them all replaced before taking it back up to 5 psi.

http://media.armadilloaerospace.com/2003_09_13/repairedSuit.jpg

 

We built another big welded aluminum main distribution manifold, and were very frustrated to find that it has pinhole leaks as well.  We went over it a second time with a bit of vacuum drawn in the manifold, in hopes of having it suck weld into the pinholes, but it still had problems.  We don’t seem to have any problems making pressure tight welds in stainless, but aluminum is giving us problems.  We are using 6061 for the machined parts, but I don’t know what alloy the Earl’s –16 AN fittings we cut off for the hose connections are.  We did good surface prep, and the welds looked good, but there was still pinhole porosity.  We are considering going to SAE straight thread fittings with O-rings for the manifold, but we might just wind up with 1” NPT, although we would really like to avoid big pipe taped connections.

 

Our big wire rope isolators arrived.  They are just giant versions of the ones we have used on the manned lander and the tail flare vehicle, big enough to absorb landing shock for a 2400+ lb vehicle.  Powered landing instead of parachute landing is still where we want to go in the future, and we will probably do some testing with it on the current vehicle.  This is somewhat higher in priority than it used to be, because getting flight clearance for 100km turns out to be a lot easier if we don’t have to worry about parachute drift.  The downside is that it would be a lot scarier for the pilot.

http://media.armadilloaerospace.com/2003_09_13/bigIsolators.jpg

 

Joseph built shelves to allow us to install all of our base station equipment in the back of Phil’s suburban, so we won’t need to have any set up time for flight operations.  The equipment we use is: laptop, joystick, Esteem wireless Ethernet, ATV receiver, TV/VCR combo, 2m/80cm mobile transceiver (not pictured), and a big inverter to run it all from the truck battery.  There will be three yagi antennas mounted on top of the vehicle.  We will get everything bolted down in place next week.

http://media.armadilloaerospace.com/2003_09_13/baseStation.jpg

 

We got a hopper spray gun from Home Depot to test spray application of our Fastblock insulation.  We had hand packed it on the engines for the small vehicle, but we need to get some idea what the spray coverage on the big vehicle is going to be.  We added some water to it and sprayed it on a test panel, but we are going to need to get a mixing system to remove all the lumps in the future.

http://media.armadilloaerospace.com/2003_09_13/sprayGun.jpg

 

 





 






 
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