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Author Topic: Inverted engine test stand  (Read 1349 times)

Offline Jim Treace

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Inverted engine test stand
« on: June 03, 2009, 10:28:08 AM »
Since I seem to be "inverted engine starting challenged", prior to building my inverted engine Brodak Spitfire, I called John Brodak to get a few tips. He said that usually once engines get use to running inverted they get easier to start. So, I was thinking, why not have an inverted engine test stand to break in the engine in an inverted position. Dose this make any sense?? Won't be very difficult to make one, but what are the thoughts of the engine experts. I am planning on using a Dixon tuned LA .46, uniflow tank.
Thanks,
Jim
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AMA 855251 "Too soon we grow old...Too late we grow wise"

Offline Brett Buck

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Re: Inverted engine test stand
« Reply #1 on: June 03, 2009, 10:47:00 AM »
Quote from: Jim Treace on June 03, 2009, 10:28:08 AM
Since I seem to be "inverted engine starting challenged", prior to building my inverted engine Brodak Spitfire, I called John Brodak to get a few tips. He said that usually once engines get use to running inverted they get easier to start. So, I was thinking, why not have an inverted engine test stand to break in the engine in an inverted position. Dose this make any sense?? Won't be very difficult to make one, but what are the thoughts of the engine experts. I am planning on using a Dixon tuned LA .46, uniflow tank.

   Engines don't "get used to" running inverted. The pilots learn the starting techniques!   I think it's generally easier to start them that way than upright, once you get the idea.  There's no reason you couldn't learn it with an inverted test stand, but make sure you have similar tank geometry.

      Brett
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Offline Randy Powell

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Re: Inverted engine test stand
« Reply #2 on: June 03, 2009, 10:55:33 AM »
Plane looks good. Looks like you may get yours done before the designer finishes his.
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Offline Jim Treace

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Re: Inverted engine test stand
« Reply #3 on: June 03, 2009, 12:04:45 PM »
Quote from: Brett Buck on June 03, 2009, 10:47:00 AM
   Engines don't "get used to" running inverted. The pilots learn the starting techniques!   I think it's generally easier to start them that way than upright, once you get the idea.  There's no reason you couldn't learn it with an inverted test stand, but make sure you have similar tank geometry.

      Brett
Brett:
Maybe that is what John was telling me-It will get easier as I learn. I didn't think I could train my engine like I do my bird dogs!  In my inverted test stand, my plan would be to have as near identical tank/engine set up as in the model.

By the way, does it matter which side the engine fuel nipple is located-inboard or outboard? Currently, my set up has the tank pickup on the outboard and engine fuel nipple on the inboard. This keeps my fingers out of the exhaust when adjusting the needle.
Jim
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AMA 855251 "Too soon we grow old...Too late we grow wise"

Offline Steve Helmick

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Re: Inverted engine test stand
« Reply #4 on: June 03, 2009, 09:30:37 PM »
Quote from: Jim Treace on June 03, 2009, 12:04:45 PM
By the way, does it matter which side the engine fuel nipple is located-inboard or outboard? Currently, my set up has the tank pickup on the outboard and engine fuel nipple on the inboard. This keeps my fingers out of the exhaust when adjusting the needle.
Jim

I would not suggest doing this. It might work, but I still wouldn't do it. You might think about using one of those R/C NV Assy's like the Tower .40's came with...puts fuel nipple and NV on same side. I haven't tried that, either, but I might. It's not that tough to adjust the NV next to the muffler if you put a knob on it, instead of the typical 90 degree bend. A pinion gear from an R/C car works well. There are usually optional ways to solve our problems, Grasshopper!  H^^ Steve
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Offline Randy Powell

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Re: Inverted engine test stand
« Reply #5 on: June 04, 2009, 08:50:26 AM »
I've had the needle valve to the outboard side on several planes without issue. I think it depends on the draw of the engine. Only time I ever had any problem with it was when using ST60s with "beer can" venturis. Not enough suction, I guess.
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Offline Jim Treace

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Re: Inverted engine test stand
« Reply #6 on: June 05, 2009, 10:03:42 AM »
Quote from: Randy Powell on June 03, 2009, 10:55:33 AM
Plane looks good. Looks like you may get yours done before the designer finishes his.
Thanks for the comment. Got it a little further along. And re-routed the fuel lines/tank/engine, so fuel pick-up is outboard. Needle adjustments should be OK and not too much exhaust blast on my "sensitive" fingers.
Almost ready for finishing, but have a lot more sanding to do... weight at this point is 39oz. This is a big body model! I wanted to keep finished weight at or below 50oz...don't know about this?
Jim
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Jim Treace
Ponte Vedra Beach, FL &
Paris, TN
AMA 855251 "Too soon we grow old...Too late we grow wise"

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