RCU Forums - BVM UAT

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David, you are correct again....as usual.
I have always mounted the UAT in a vertical, or close to vertical position, and have never shaken, or stirred, the airplane to get the air out. Let the engine run at an idle for a few minutes, and guess what? No problems.

About felt clunks. I was told by a knowledgeable turbine manufacturer along time ago, that they were seeing felt particles in the fuel needles upon occasion. Clogged fuel needles don't deliver the fuel as well as clean ones do. That's my story, and I'm sticking to it!

HArley Condra
BVM REP
Team JetCat

I remember hearing about felt shedding particles too. Pleated paper clunk, THE way to go!

What is referred to as the "BVM" UAT actually comes from up here in Wisconsin at Jeff Seymour's shop----> SWB Turbines.....he designed them for his government turbine project planes......the semi-permeable bag is off an automobile fuel pump......you can get them at most auto parts stores....they are too big as they come and must be trimmed down.......any semi-permeable membrane, like on Woket's or Todd's will work......neat technology letting liquid but no gas thru.....originally designed for membrane oxygenators many years ago on heart-lung machines for heart surgery and also used extensively in reverse osmosis units, big and small.....

Of course, we all flew for years with those skinny little saddle tanks in our D/F that were prone to unport and we all seemed to get along with the centered tube in a 2 or 4 oz round DuBro hopper.....if you want the cheapest way to go, that's still it......I built a Roo for my buddy last year and I had a 4oz round tank and no UAT handy at the time......He has umpteen flights on that Roo with literally hundreds of chicken flops, etc. and no flameout due to bubbles....Rob Janiger, Dave Elsinger, Brian French, and I put on over 1000 flights on Rob's old Avonds F-15 with a 2 oz round hopper with centered brass tube, with never a bubble flameout due to the hopper.........

I just like the convenience of the nice 6 mm size nipples on the UAT.....the ability to mount it almost anyway you want from horizontal to vertical, facing direction of flight or backwards......plus the added filtration benefit.....If you want to cheap-charlie it, you can build one up for about $20.00 or less.....too much hassle for me......I've got enough trouble just getting my gear doors and struts to assume the landing position time after time.........I'll let Jeff screw with the UATs;)

So just pays yo' money and take your pick......

Tom

huh huh huh you said nipples huh huh huh

So did you!!!!!;):D:D

Only the SWB underground direct UATs come with nipples......as usual anything from BVM is done politically correct....no nnniiipppplllleeeessss! Just boring brass fittings.....:)

T...

During the Apollo program (and probably Gemini and Mercury before it), similar technology was used to get fuels to feed in zero G. Think about it. In trans-lunar space, when you need to fire the Command Module's big SPS (Service Propulsion System) engine and there is no up or down in the tank (zero grav), a clunk ain't no good. So there were stainless steel screens or meshes in the hypergolic propellant tanks that used the same surface tension effects to keep the fuels clinging to them (and I think kept them on one side) to allow them to be fed, via pressurized feed, the the main reactant valves.

Same thing makes the BVM UAT and my pleated paper clunk work!

I think Apollo also used Woket's membrane to separate the tinkle from the doo-doo from the sweet smell of roses......gotta believe hydrogen sulfide and sewer gas in a high oxygen environment made those astronauts think twice about climbing into that module without their own personal semi-permeable membrane...But maybe that's just another urban legend.....?

T....

No, in fact urine was handled the same as on Gemini. You put a prophylactic like device on your weenie. It had a tube on the end and it channeled the moon explorer's pee into a reservoir or out into the void (I forget which). But for crap, that was awful. They had a paper device shaped like a top hat with contact paper on the brim. You stuck the brim to your a s s and crapped. The whole inside was contact paper too so the turd stuck to the walls rather than become a trans lunar Baby Ruth! Then you cleaned up, threw in a biocide tablet and folded the two sides of the brim together to seal it. Then came the worst part! You had to kneed it around with your hands to fully mix the biocide with the crap! One early Apollo astronaut (I think it was Wally Schirra) once told the mission planners to leave an hour in the schedule for each guy for each crap. He said that it really took that long to do all of that in zero G, there was no way to get the job done any faster! [&o]

Hopefully we won't get into feminine excretory hygiene in zero gravity on this family oriented forum..[sm=spinnyeyes.gif]

Don't worry, the Space Shuttle is the first with a zero G toilet that works on air suction and a centrifugal fan system to sling the debris outwards, radially. In low Earth orbit, the sh_t REALLY does hit the fan!

In reply to David Ribbe, my BVM UAT instructions ( and I have UATs in both of my BobCats, StarJet and Sabre) state that before the first flight the UAT must be purged and outlines the procedure, which must be repeated if the UAT is ever drained. I believe the UAT works best if mounted vertically or at least at 45 degrees or so as per BobCat. In comparison the simple header tanks in my F4 and F15 and Mig 29 are automatically purged on every refuel. Please be assured that I am not "having a go" at the UAT (as you see, I do use them) but all three of my flameouts in the last year have been with UATs and none have been experienced with the simple header tank. Apparently the folds in the sack CAN trap air bubbles. That is my experience to which I should add that, to date, the 20 flights I have logged with my second, JetCat P70 powered, Bobcat with a UAT have been flawless. That combination (BoBcat/ P70) is a pure delight.
Regards,
David Gladwin

Are bmt turbines available? I seem to be having trouble getting any e-mail replys. it may just be my crumy e-mail system.I need a 120. Andre, plz let me know something.

I'm not having any luck with the BMT rep here either
Cheers
Ken

Hello David Gladwin,
No problem here...., and I don't disagree with your mounting comments. I do suggest that if you are having flameouts with a properly used UAT, that you look at the rest of your system... Flameouts for most of us simply never happen....
I NEVER had one in my Bobcat, Bandit, or F-16.... which were equipped with UAT's... (the F-16 has flamed out on the ground when I forgot to purge the UAT).

I would always point the nose up on a new model.... for a lot of reasons.... and always purge the UAT if it has been emptied, and is mounted near horizontal.

Regards, David

Not had a UAT flameout since I followed the recommended procedures. That is, however, exactly my point, NO procedures are required with simple header tanks for perfect operation. My systems go through EXACTLY the same checks whether UAT or hopper tanks and are designed and installed on exactly the same principles.
Regards,

David gladwin.