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ED Hunter MK IV - Prop nut assembly damage


GlidingGuy
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Hi there,

A friend of mine recently dropped off a damaged ED Hunter which will be going in an old Junior 60 of his. The prop nut/spinner assembly's thread has been stripped and due to the design of the engine we cannot simply use a standard nut on the crankshaft as it does not protrude out of the engine as per usual (there is no damage to the thread on the crankshaft). I was hoping these two questions could be answered:

- What thread is it on the crankshaft?

- Where could I source another one or a suitable alternate part?

Thanks in advance,

Luccaaa

crank1.jpeg

crank2.jpeg

crank3.jpeg

Edited By Luccaaa on 06/08/2019 22:35:02

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Posted by Engine Doctor on 07/08/2019 08:50:40:
Posted by Braddock, VC on 06/08/2019 23:46:49:

Get in touch with Weston UK.co.uk they make ED engines now and can probably help you though it might be helpful to have an extra arm and leg. Alan, the owner, is really he!lpful.

You might be lucky at Westons but I dont think he will have any spares for a Mk 1V Hunter .as He currently only supplies the Super Hunter which is a much later engine .Ask for Alan .their number is 01795-522020 or 521030.

Alternatively try putting  an add in the classifieds for a second hand spare or a clapped motor as the cranks usually survive  . There must be thousands of bits laying around .Failing that used Hunters regularly come up for sale on the BMFA , Rcm&E classifieds or on E-bay .

Good luck and hope you get it going

 

Edited By Engine Doctor on 07/08/2019 08:58:34

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Posted by jeff2wings on 06/08/2019 22:47:17:

The crankshaft is broken,the threaded portion should be much longer,it my be possible to heat treat the end of the shaft to be able to drill and tap it for a stud,hope that helps.dont know

Ah, that’s a shame! I never saw it when it was undamaged so I don’t really know much about this engine. I like the idea of tapping the inside, I’ll look into it 👍

Thanks all for the information, it’ll certainly come in handy. I’ll let you know how this one turns out.

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This might be the sort of question to put to the Wizard of Oz ( Brian Winch ) and I think there is an email address in RCME. I would think drilling the crankshaft would be near impossible and that making an adaptor to go onto the remaining thread, maybe Loctited on, and then having a reduced diameter to take the prop and a standard domed nut would be easier. Ask the Wizard.....

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Thanks again for the suggestions. Sadly, the Junior 60 was literally built around this engine, with a custom exhaust, Cowell and a home made fuel tank. This means that it would be very difficult to install another engine in it's place so If we want to see this model fly we will need this Hunter to be in working order! It's a shame the shaft is damaged, the rest of the engine is in really good condition.

Thanks all.

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Posted by Luccaaa on 07/08/2019 13:14:03:

Thanks again for the suggestions. Sadly, the Junior 60 was literally built around this engine, with a custom exhaust, Cowell and a home made fuel tank. This means that it would be very difficult to install another engine in it's place so If we want to see this model fly we will need this Hunter to be in working order! It's a shame the shaft is damaged, the rest of the engine is in really good condition.

Thanks all.

P.M. sent

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Ah yes,

That certainly looks like it should. The one in this engine must have snapped long ago. It hadn't been used for a very long time before we dug it out of a model and cleaned it up.

Here it is back together, albeit with the broken crank. (it was even dirtier before!)

hunter1.jpeg

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Posted by jeff2wings on 10/08/2019 21:00:25:

Just to show how the crank should look.............img_20190807_142928.jpg

C.S. repo

The reproduction CS engine while looking like a Hunter differs in detail to the original and while it captures the spirit of the Hunter is a different animal. The original had a taper machined shaft ,not a split tapered colett and all the repro threads are metric instead of BA. There may be other differences 

The beauty of the Hunter was that it would start if you gave it a hard stare smiley . I have a few in my collection but won't strip to photograph the crank and associated parts. I would definitely look for a replacement crankshaft rather than try to repair the existing one as it broken in a critical area. A prop flying off causes serious damage !

Good luck and hope you get it going.

 

Edited By Engine Doctor on 11/08/2019 10:00:50

Edited By Engine Doctor on 11/08/2019 10:04:06

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Thanks for the encouragement, I've certainly had some experience with props coming off these engines! I've thought about it and now believe my only 2 options are finding a spare crank as you've mentioned or making a new one.

I've contacted someone who may have a spare so fingers crossed they do. If not, I'll have to think about the second option. I don't have the facilities to manufacture a new one at my home but someone who does has very kindly offered to make one for me.

I'll let you all know how it turns out.

Thanks again,
Luccaaa

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Hi Luccaaa You should be able to find a spare as there must be thousands of them lying around, The trouble is that many folk think that old ED bits are worth a mint and ask stupid prices . I have seen old motors that are smashed and bashed at Swap-meets and the asking price is just too high. Yes they have value but just for spares. You should be able to pick a crank up or even a bottom end for £10 to 15 .

The ED hunter came in two forms . A short Shaft version that was rarer  and the extended shaft version that you have . The extension was actually the prop driver and the crankshaft is the same in both types  it was probably the extended prop driver that caused the Hunter to vibrate so badly .The short shaft just uses a shorter prop driver as used on the Taplin Twin Aero version.

Edited By Engine Doctor on 11/08/2019 10:53:21

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