Using a socket driver to engage with prop nut

[Andy J]

Is there any issues using a socket driver to engage with the prop nut to start a larger engine as find it near impossible to get a decent contact interface between the engine prop nut and the starter cone?  Will of course include an  inline ratchet drive to allow removal of the socket once the engine starts.

 

Little lost as how to couple the inline ratchet to the starter but sure I can think of something.

 

 

[Andy Stephenson]

I think you would be in danger of loosening the prop nut by using it to start the engine, particularly if it's tight to turn over.

[Denis Watkins]

Just a note of the two places where I fly, do not allow flying without a spinner on the motor.

[Andy Stephenson]

The original BMFA rule was to use a spinner with a nose radius of greater than 5mm but it was later revised to 7.5mm, then for some reason it was dropped altogether. I heard a rumour that it made little difference in an accident how sharp it was or whether one was fitted or not.

[Engine Doctor]

Not a good idea. Direct drive to the nut would invariably loosen it . I had a magneto Zenoha 45 that refused to hand start. I used a geared starter on the domed prop nut and flipped it with gloved hand to get it spinning. Using a rubber drive in the starter allows some slip , a bit like a clutch and nut never came loose . However this domed prop nut fitted over rhe main nut that held the prop on . It was machined so as to fit the shaft over the existing nut .

Larger engines either glow or electronis ign petrol usually start easily by hand ?

[Engine Doctor]

5 minutes ago, Andy Stephenson said:

The original BMFA rule was to use a spinner with a nose radius of greater than 5mm but it was later revised to 7.5mm, then for some reason it was dropped altogether. I heard a rumour that it made little difference in an accident how sharp it was or whether one was fitted or not.

Yes I think you correct. However any spinner is better than a bare nut on a shaft as these can get fixed into a person/ wound or clothing on impact and make a much  messier injury than a spinner nut .

Edited February 18, 2023 by Engine Doctor

[Don Fry]

Rumour or not, one of my club members (France) flying a 5cc combat aircraft lost orientation his model in the melee, and it hit his head, bare shaft, and it punched through his builders helmet, skull, and into his brain. Physics says, stress loads are reduced by radiused strike surfaces. 

[Paul De Tourtoulon]

Silly french pylon racing rules don't allow plastic cones just a nice head splitting metal nut,,,

[Andy Stephenson]

Could it be that plastic particles in a wound are the worst option.

[Peter Jenkins]

2 hours ago, Andy J said:

Is there any issues using a socket driver to engage with the prop nut to start a larger engine as find it near impossible to get a decent contact interface between the engine prop nut and the starter cone?  Will of course include an  inline ratchet drive to allow removal of the socket once the engine starts.

 

Little lost as how to couple the inline ratchet to the starter but sure I can think of something.

 

 

The starter cone insert is designed to be removed and rotated so that the flat back of the cone with the hole can be pressed onto an engine without a spinner.  I have on very rare occasions wanted to start my engine without the spinner on and that design feature works well.

[J D 8]

            I have a couple of models who's engines are without spinners that are started as above. A dome nut and washer locates the prop and keeps starter in position when operated.

[Bruce Collinson]

Just Engines sell alloy domed spinner nuts with virtually any mainstream thread you require and these have several advantages.   Until I have finished with ground running and tuning, they are much easier to remove if the prop and/or the cowl has to come off compared with a spinner backplate etc.   They grip in the cone of the starter very well.

 

BTC

[Nigel R]

I like those big spinner nuts JE sell too.

 

 

[Andy J]

Thanks for the responses. Certainly was not aware of the BMFA rules about fitting spinners. Actually do have a spinner on order for this particular engine installation but had to resort to ordering one from the far east as there seems to be a shortage of 2.25inch diameter aluminium spinners in the UK at the moment.

Certainly would be concerned about the potential for loosening the prop nut as the engine does have a tendency to keep throwing the prop when it backfires, so using a socket drive is obviously not the way to go to overcome the issue of turning the engine over with one of my starters due to the lack of friction between the starter cone and the prop nut.

[Peter Jenkins]

Andy, have you tried turning the starter cone round so the flat part contacts the prop and prop nut.  They designed the cone to provide that feature.

[Andy Stephenson]

How about making a couple of "dogs" to engage with the prop instead of trying to grip the prop nut. I've seen this done using a disc on the starter shaft with studs protruding, covered with rubber tubing to cushion the prop.

[Martin Harris - Moderator]

[Andy J]

Andy, the concept of dog teeth to contact the prop could be a possible option but I would be concerned of possible contact with the cowl.

Must have an old spinner in the spares box so will fit that whilst I await the one from overseas.

Once the engine gets ran in hopefully it will be more easily turned over and started by hand.

I also fitted a new carb pump diaghram a couple of days ago which I hope will have improved the engine priming with the choke closed.

[J D 8]

16 hours ago, Martin Harris - Moderator said:

  Every club should have Hucks Starter.😂

[J D 8]

17 hours ago, Andy Stephenson said:

How about making a couple of "dogs" to engage with the prop instead of trying to grip the prop nut. I've seen this done using a disc on the starter shaft with studs protruding, covered with rubber tubing to cushion the prop.

  Some early model engine starters worked this way with a small flywheel with an over run dog clutch that released when engine fired, The power came from a clockwork spring that gave you one go at spinning engine over for a few seconds before needing a rewind.

[Jon H]

I have not had trouble with this type of dome nut except with modern hard plastic type starter rubbers. If you are able to find a soft pure rubber starter cone they work very well indeed. 

 

As for the spinner radius thing while the spinner radius might help in the case of a small model, i would say the whole thing is irrelevant if you get flattened by something like my Sea Fury at 80 inches and 23lbs. Even a 'small' model like a 40 size trainer will punch through the roof of a barn or car with no trouble so the spinner is probably not important with that amount of energy involved. Also if you have been smashed in the head by a model then something somewhere has already gone really wrong and that root cause is probably the one that should be dealt with. 

[Paul De Tourtoulon]

9 hours ago, Andy J said:

 

I also fitted a new carb pump diaghram a couple of days ago which I hope will have improved the engine priming with the choke closed.

Have you adjusted the 'pop up' needle valve pressure ?.

[Andy J]

What is the pop up needle Paul?

[Mike T]

Mick Reeves does it: starter  (scroll down to 'biplane parts')

So I copied it to use on my 1/4-scale Pup:

 

 

(there should be a nice pic here, but forum software says "no".  Just imagine a geared starter with a 19mm socket pushed into the rubber cone.  Plenty of grip, plus a little 'give')

 

 

[Andy J]

Thought I had seen one on the MR site could not spot it when I looked as went to the accessories page a couple of days ago. Do you find it does any damage to the prop nut Mike?

 

Its all a bit bizarre regarding the starter. Fitted a three inch spinner yesterday and the cheap and tatty 12v starter easily started the engine on a 11.2V 5000mah lipo. Tried the larger geared starter from JE using the same battery and it would not even get the prop passed TDC.  Not at all sure what voltage is the JE starter should run on as unsure which of the two types he sells as I purchased it was some years ago.  Even looked last night for a 4S lipo to see if I can speed it up, but given a lipo will be at least £60 think I will just stick to my cheap and tatty 12v job.