The Biplane Forum > Biplane Builder's Forums > Starduster > Max power ground test

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Old 03-26-2012, 12:39 AM   #1
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I'd like to sit on the ground and go full power to test my rebuilt fuel system...soon. Has anyone hooked up a scale to the tailwheel to read the pull? I'm wonder what range of a load cell you would need. Thanks
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Old 03-26-2012, 07:24 AM   #2
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for a 300 HP Skybolt here in germany they made a ground test and measured400 kg (880 Ibs) of static thrust.

With a 180 or 200 hp Engine it might be roughly 2/3rd of this value

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Old 03-26-2012, 11:39 AM   #3
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I didn't use a scale but I did that when I got my Pitts engine ready to run. I tied the tail to my truck and ran it a bunch. That also gave me some confidence that my fuel system would deliver enough fuel. I put the tail down in a ditch to simulate steep climb attitude and ran it like that too.

If you have a standardaircraft engine and aircraft propellor and a tach, then all you need to to check is the static rpm is sufficient for that prop/engine combo.

You should be able to find some rpm numbers with a little internet search. If you have an engine/propcombination same as used ona certificated airplane, then the type certificate for that plane should give min takeoff rpm.

Just another idea.
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Old 03-26-2012, 01:59 PM   #4
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"<table ="tableBorderpost" align="center" cellpadding="3" cellspacing="1"><td rowspan="4" ="msgOddTableSide" style="width:140px;" valign="top">kjkimball

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[img]ajax/imgs/bipeic&#111;n.gif[/img]Pitts Model 12 etc

<td ="msgOddTableRow" valign="top">[img]forum_images/quote_ic&#111;n.gif[/img][img]forum_images/reply.gif[/img][img]forum_images/bullet.gif[/img] Posted: Mar/08/2009 at 20:25

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540 lyc parallel is around 380lb. If your engine
of choice is 412, plus the goodies, plus the PRSU, prop, coolant, etc.,
Randy's info is still accurate. Besides, all the lightweight doo dads
you put in are on the wrong side of the CG making it more likely you
will add ballast to the tail.

The fuel use for 10-50 hrs a year is not that much more costly.

If it were as easy as the car engine guys want you to believe, it would be rare to see a lycoming in an airplane.

To touch on the TI stuff you used, keep in mind Ti is like a rubber
band and has greater elongation than steel. Not really the best choice
for drag wires especially if the airplane will not be significantly
lighter overall.

FWIW, you need to buy an angle valve 10:1 compression or 11:1
compression Thunderbolt or Lycon engine to get 325hp. The best you will
see from a parallel valve 540 is about 310 even with 10:1 pistons. The
yellow airplane with 325 painted on the cowl had an engine in it that
dyno'd at 290 according to the engine builder MB. Hale simply painted a
cool number on the cowl according to MB.

Final point. Thrust makes airplane go not HP. determine the real thrust available from you alt engine and compare it to the aircraft engine for that airplane. Gotta get more thrust from the alt engine if the setup weighs more or you are going backwards.

FYI, 11:1 Lcon 540 on Bulldog get 1250 lb thrust. BPE M14P gets 1850 lb thrust. 260 lyc in S2C 960. these are numbers you need to compare your alt engine to. Not HP."

This is from this thread.

Interesting reading.


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