EA81 crank to flywheel flange safety bolt?

[MadMuz]

My last couple of EA81s had the input shaft bush hole tapped out and a bolt locktited in because the flange is only pressed onto the crank.... although, it is pressed very well... I doubt very much if the flange could be pulled off of the crank by any normal running, even with a prop bolted on (direct drive), however, I guess if a prop were slightly out of balance, the harmonics could eventually vibrate the flange loose on the crank shaft, so probably a safety bolt would be a good idea, even if just for peace of mind.I remember it is a 16mm fine tap that is needed, just wondering if others have done it , think it is worth doing (if a prop is out of balance a bolt will only delay the inevitable..... balance your prop and good pre-flight should catch sneaking flange some might argue)I cant remember if the thread should be left or right hand? From memory we just did it with a starter tap, once done, a finishing tap (less tapered leading end into the hole) and lock tited a bolt and washer on it.... is this what others do? Or in pusher configuration, do people not bother? The crank is only at the last 10-15mm in the bottom of the hole anyway, the first 20mm is just the flange.... it might be argued that the process is pointless because there is only going to be 8-10 threads into the actual end of the crank, and how much in reality can say 10 threads hold when there is a wopping great prop trying to rip the end off the crank anyway? :I am thinking of trying a 3 blade 54" warp drive prop, so am thinking of the rotating mass on the pressed on only flange, however the rotating mass of a 3 blade prop may not so much worry the pressed on flange, as much as maybe chew off the entire end of the crank (flange and all) Perhaps a 2 blade 54" warp prop may be more suitable (less rotating mass)?

[MadMuz]

No one flies EA81 direct drive?....Any guesses even?

[mad max]

Don"t worry M/Muz, The prop usually falls off when you switch the engine off. A bloke flew in to a fly-in in SA many yrs. ago and proudly taxied up then switched off his VW engine and the wodden prop. promptly fell off onto the ground. ;D

[MadMuz]

I"m more worried about it coming off when it is running..... falling off when you stop isn"t so bad

[mad max]

I remember 100yrs. ago when I had a sub. direct drive wooded prop. that used to frighten me (and I eventually realised it was the noise) I used to wonder about that flange thingy but as no-one seemed to think it would fly off and I"d never heard of one flying off I just relaxed and forgot about it. :-

[MadMuz]

Thanks Max, yes, evidently the flange is pressed on with cold crank and hot flange and the likelihood of it ever coming loose is remote, I will just tap and bolt it, just because I can

[GraemeMonro]

Might want to stay with a wood prop on a direct drive.Graeme.

[mad max]

I"ll be up there with you one day in a direct drive M/Muz as I intend to build a replica of my first Bob Higgans machine as I still have one of his tails and a VW. Next year I intend to build a steel arch hanger in my back yard and have a little gyro museum of fully flyable machines. A little bar in the corner with home brew equipment and a few dirty pictures. (A real man"s shed) ;D

[MadMuz]

Might want to stay with a wood prop on a direct drive.Graeme.Why is that Graham? What is the difference between a 55x34" timber prop and a 54" adjustable pitch lighter carbon prop? This is a genuine question, not simply a snappy return comment, I really am interested why this may or may not be true?

[GraemeMonro]

I can"t remember the exact reason Murrey.Bert Larkin once gave me a lesson about engine pulses on direct drive props and to always use wood and not composite.I am sure some others will know a bit more on this?Graeme.

[MadMuz]

Thanks for that, hopefully others might know and add more info?

[AirWolf]

I remember something about that Graeme, Jabiru specify wooden props on their fixed wings, but now I see a lot of them with composite props. Would be interesting to know the reason. Ray.

[tonydenton]

I don"t know anything about props but rob started making his for the jab"s. then when the factory wouldn"t buy them he sells them direct

[blakemorem]

Hey max about the mans shed when you have 8 gallons of chilled home brew at your reach it"s a dangerous situation. You seem to become perpetually pissed. Hey talking about 3 blade props if your prop has been removed and re mounted is there and specific alignment to the Rotax hub for the engine pulse or is it pretty much the same whatever the stud hole. I"m guessing the latter as 3 blade should be balanced. Mike.

[mad max]

I"ve always bolted 3 bladers on at random Mike. Never had a problem. The lady down the road makes a mean Liqueur and has given me a jar of ethanol. I wonder what will happen if I tip a bit in my fuel tank? :-