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gday guys quick question,i have just swopped over my prop from a 68 inch warp drive to a 72 inch bolly propnow the question is does anyone have a scooby doo engine on the back with 80 horses, throwing a 72 in prop around?? the engine liked to run at 4800 with the 68" warp drive, now with the bolly on its seems very slippery and likes to go fast, motor runs at 4600, and with i believe 10 degreess pitch if i have set it up right, can anyone tell me other info, it seems to be very high tollerance with a larger prop, to be half a degree out seems to change a great dealis there any standard formula for this set up?cheeradrian.
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Adrian,Now you have opened the can, how are the worms?Bigger props give you more bite on the air but the pitch is really going to be determined by the tip speed of your new prop.less pitch will give you lousy climb but quicker cruise, more pitch vice versa.someone else out there may be able to correct me but I seem to remember from the dim and distant past that the optimum tip speed is somewhere around mach .6 to .7 (450-525 mph?)there is a formula somewhere that gives a factor to divide engine rpm, gearbox/re-drive ratio that gives optimum tip speed. if I can find it I will post it.Mark.
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less pitch will give you lousy climb but quicker cruise, more pitch vice versa.Other way round Hoorag.
Adrian, if you set it to limit the engine to just under the max climb rpm you want, youll have the best of both.
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Thats about it, set pitch so that at full throttle you get the engine revs you desire, it can take a while to get it right.My old suby could only pull 4400 at full throttle and cruised at 4200 so you have a much improved ride to mine. However, up side was that I quickly learnt what "behind the power curve meant"!
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thanks for you import guys , i just thought i should set it back to where the engine liked to run, at 4800 , but now i believe where i have it set, its not to bad, the climb is not bad but the cruise is alot better, cheersso 10 degrees , at 4500 - 4600 , is the goadrian
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Adrian,What reduction ratio are you running?
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well . my redrive i understand is a rick douglusbelt drive 2.2, 1if that makes senceill try find the guff i had on it somehwhereadrian
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so 10 degrees , at 4500 - 4600 , is the goadrianNope! As young Mark was trying to point out, you have just taken your first step toward "the House of Giggles" (At least I THINK that is what he was trying to point out.
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thanks fred . thats very helpfuli guess there is a happy medium with what can be achived with out going over board,i must admit my cruise speed is higher,but i few more ground runs should do the trick,but i do get the same response from all those grounds people, "nike supporters i call them"they all say the same thing, flying in a death seat, or some sorta anti - negitive responsei can only think bugger them lolthanks for the infoadrian
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Good post Fred - welcome back.
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thanks fred . thats very helpfulNo problems, Adrian. You"ll still be buggerizing around with it in 10 yrs time, but that"s part of the enjoyment.Good post Fred - welcome backThanks Tim. Feet back on the ground again, so can get back to the REAL important things.
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flying in a death seat,Wen i hear that sorta stuff Adrain, i just agree with um.Usualy shuts um up wen your come back is sumthn like, " yup, if you sat init, youd no dout find sum way of killn yself".
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flying in a death seat,Wen i hear that sorta stuff Adrain, i just agree with um.Usualy shuts um up wen your come back is sumthn like, " yup, if you sat init, youd no dout find sum way of killn yself".OR..... "If I only had little balls like you, I probably wouldn"t do it!!"
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Oh Mr Bird,that last comment was absolutely disgusting,don"t you think :"( Kym.
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Kym/Bosca, The truth hurts most knowitalls egos. The sad part is that Davo"s coment is true too many times.Adrian, The information you are looking for is on the Bolly web site.Cheers Des Garvin
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