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Anyone know how to make a scale dummy engine pinwheel?

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Anyone know how to make a scale dummy engine pinwheel?

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Old 08-03-2010, 05:56 AM
  #1  
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Default Anyone know how to make a scale dummy engine pinwheel?

I'm custom rebuilding a Discontinued Fokker .60 DR1 and I'm doing some planning. ( My favorite part of the build ) I believe the plane is between is 1/5 scale and I'm thinking of buying the William Brothers or AZ Models 1/6 scale LeRhone. I would like it to spin from the prop wash effect and I was wondering if any one can send me a link or explain in detail how I could make it work? I'm also planning to run a O.S. 91 FX with a pitts with it.

Thanks,


Pete
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Old 08-03-2010, 10:30 PM
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Default RE: Anyone know how to make a scale dummy engine pinwheel?

I am planning to do the same sometime. The ones I have seen have been on engines that did not have any obstructions at the front of the engine like an Enya or Laser 4 stroke or if a 2 stroke a rear intake engine. Then a big bearing is put over the crankshaft housing and the model engine is attached to the outside of the bearing. Not much room between the prop flange and the carb on the FX to do that; also, dont go full throttle with that engine on the model, it will blow the wings off.
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Old 08-04-2010, 06:26 AM
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Default RE: Anyone know how to make a scale dummy engine pinwheel?


ORIGINAL: TFF

I am planning to do the same sometime. The ones I have seen have been on engines that did not have any obstructions at the front of the engine like an Enya or Laser 4 stroke or if a 2 stroke a rear intake engine. Then a big bearing is put over the crankshaft housing and the model engine is attached to the outside of the bearing. Not much room between the prop flange and the carb on the FX to do that; also, dont go full throttle with that engine on the model, it will blow the wings off.

Are you ready for a shocker? When I drove just outside of NYC (460 miles) to pick up the plane, the two owners before me had a mint condition (Before Surpass) 1983 O.S. 1.20 engine in it. You know, the one that looks like a Saito? [&:]

Soon as I got home I took the engine out, cleaned it and put After Run Oil in it and wraped it up in a clean towel and put it in a new shoe box. Oh buy the way, the landing gear was busted and has to be re-soddered and wired.

Basicly I paid for the engine more so than the Fokker DR1 if you know what I mean. I plan on re-designing the landing gear anyway so it is more scale like. I noticed that the Hanger 9 Fokker DVII's landing gear is the same size, all I have to do is drill the holes in the blocks.

Anyhow, I guess the bearing idea is a good one. The .91 will have plenty of power for the extra load and still give me enough nose weight. I heard somewhere that you could have the dummy engine on a platform with a bearing, not attatched to the motor rotating on a bearing. The prop wash actually turns the motor?

Maybe I can get some Moderator input on that?

Thanks,

Pete
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Old 08-04-2010, 07:14 PM
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Default RE: Anyone know how to make a scale dummy engine pinwheel?

One I have seen had the exhaust pointed at the dummy to pinwheel it.
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Old 08-05-2010, 06:47 PM
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Default RE: Anyone know how to make a scale dummy engine pinwheel?

Thanks, I'll look into the exhaust method as well. It seems that not many people have done this I guess.

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Old 08-05-2010, 10:31 PM
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Default RE: Anyone know how to make a scale dummy engine pinwheel?

You know this is going to sound like a joke.but I would guess it would be setup a lot like spinners on a car wheel !
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Old 08-05-2010, 10:41 PM
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Default RE: Anyone know how to make a scale dummy engine pinwheel?

Someone from Europe or England(?) did this a few years ago. A 'cup' was fit onto the thrust washer (or a new thrust washer was made with this modification) so that the inner race of a bearing could have an interference fit onto it. Then the (metal) dummy engine was built so that the crankcase had an interference fit to the outside of the bearing. The friction of the bearing caused the dummy engine to spin. When the engine quit the dummy engine continued to spin for some time. It was very convincing! A similar process was done(?) to mimic 'contrarotating props' (?) on a Westland Wyvern. Hope this makes sense!
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Old 08-09-2010, 01:27 PM
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Default RE: Anyone know how to make a scale dummy engine pinwheel?

ORIGINAL: ARUP

Someone from Europe or England(?) did this a few years ago. A 'cup' was fit onto the thrust washer (or a new thrust washer was made with this modification) so that the inner race of a bearing could have an interference fit onto it. Then the (metal) dummy engine was built so that the crankcase had an interference fit to the outside of the bearing. The friction of the bearing caused the dummy engine to spin. When the engine quit the dummy engine continued to spin for some time. It was very convincing! A similar process was done(?) to mimic 'contrarotating props' (?) on a Westland Wyvern. Hope this makes sense!

[&:] I'm a little lost. A picture of it would help.


foodstick
You know this is going to sound like a joke.but I would guess it would be setup a lot like spinners on a car wheel !

That's what I was thinking. I was wondering if I could make a wooden bracket with a bearing and the fake Oberursel attatched to it. And when the engine runs, the prop wash would spin it. I was wondering if it would work? Sorry for being such a odd ball, but I'm such a attention $lut when it comes to my planes having special functions. My Hanger 9 Fokker DVII has a GWS Micro Servo moving the pilot busts head, so when I hit the rudder, the head moves with it. That little detail gets quite a bit of attention at shows.

Pete



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Old 08-10-2010, 10:33 AM
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Default RE: Anyone know how to make a scale dummy engine pinwheel?

Hi Oberst- just think of a screw-on bottle cap but without the threads. Drill a hole in the center of this 'cap' so it fits the engine's crankshaft. Slip this onto the crankshaft and against/ over the thrust washer on the engine's crankshaft (just as if you were putting a propeller onto your engine). The 'cap' needs to be large enough in diameter to clear the engine's crankcase. It also needs to be long enough and 'strong' enough for a bearing to have a snug interference fit. The bearing's inner ring will 'capture' the 'cap'. An Enya or similar rear carb engine would work best for you will need the room for the dummy engine to spin. The dummy engine's crankcase needs(?) to be made of metal so it can be pressed onto the outer ring of the bearing. Remember, the dummy engine will spin up to fairly high rpm's so it needs to have good structural integrity against centripetal force. If not, you'll end up with a 'scale appearing' hole in your cowling!
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