Alu drive

[Aerosan]

Hi gents

I had a v-beld drive on my plane, wich took just about half my hp , and now Im having a toothed pulley made up in place :D . I have one question, if it isnt anodised it will be eaten by the beld, correct? The center of the hub takes a set of bearings, will the ID change if it gets anodised? The bearings will not fit then?

Sorry to ask a dumb Q but i need to know.
Thanx guys

Cheers San

[Morph]

San,

The Challengers all have a high redrive with a 2.62 to 1 ratio. Both are made of Aluminium and are not annodised. I have 540 hours on this unit and neither of the pulleys are showing any significant wear.
Make sure that the belt is correctly tensioned at all times, if too tight it will wear the pulleys and put lots of strain on the bearings of the big pulley and the crank. you should be able to just slide the belt on the big pulley, or should have a play of about 8 to 10mm on the belt. Any decent belting company can supply you with the belt and pulleys

[RudiGreyling]

Hi gents

I had a v-beld drive on my plane, wich took just about half my hp , <Snip>

Sorry to ask a dumb Q but i need to know.
Thanx guys

Cheers San

Hi San,

Belts are 'typically' good at transferring power, if they did not they would burn up, since the only place the 'loss' power can go is heat. I doubt that it would have robbed 1/2 your HP, i.e 50% that means a lot of heat.

Did the V belt get very hot? If not then don't expect the toothed pulley at the same ratio to show a significant (50%) power increases. Just my 2c of engineering thinking.

Regards
Rudi

[Aerosan]

Hi gents

Rudi We did a small test whereby we removed a beld at a time and then checked the engine rpm and prop rpm. After removing 2 belts we picked up 550 rpm with no slip!! as soon as you go more than 2 belts it just goes for a ball. It did create a lot of heat and normally the rpm wouldnt be as good at the end of a flight as what it was in the begining. I spoke to Trevor Davies who warned on just this matter, he explained that in the early days of the Tunderbird they tried a v beld drive but it failed badly. BTW I dont know who in here has ever dealt with Trevor, but I have to say he is one of the most truting guys I have ever met. A real pleasure to deal and to chat with. A real gentelman.
V-belts have a big contact area and they need to be tentioned. This places stress on the bearings and crankshaft.

I hope to better my whole system with the change.

San

[RudiGreyling]

Hi San,

Thanks for the detailed explaination, I guess the toothed belt is just better less friction than multiple V belts and can't slip at all. If your belts got hot it meant they did sip some power away, but I doubt that 550rpm would = 50% power loss. Let us know how your conversion go, the engineer in me will be listening. (Are you keeping the same ratio?)

Regards
Rudi

[Aerosan]

Yes sorry you are quite right, it wasnt that bad.
I was down about 1000 rpm on max trotlle and it would increase slightly from say 800 to 1000 over the first 5 mins or so.I.e. I would always rev 5900 and it would come down to 5600. I assume that that would be more or less the time it took to get to temp on the belt.
Yes the drive would get so hot that a little grease would always seep out of the bearing (sealed)
We will see when I get my new drive, I will then be able to post something on rpm and thrust. Duck and myself will tie (well see how exactly but you get the idea) the plane down to a brick or two, place a trekskaal in series, and give her some carrots. Then well change the prop to my warp and see what the best is we can get out of that and then well change the drive and redo the whole thing. Im interested to see how much more,if any , rpm Ill get out of the timing belt set-up. The idea is to see at wich rpm a predetermend trust is reached and maintained. I think the v-belts will need a higher rpm to get there than the toothed belt. if not if it does then ..well..... I think it will be at least a good indication if nothing else (I hope)

[Duck Rogers]

Duck and I will tie (we'll see how exactly, but you get the idea) the plane down to a brick or two.....

More like a brick wall or two :D
....and I'm not even gonna get paid for this

Duck Rogers

[Duck Rogers]

I have 540 hours on this unit.....

Is this the same êrrie you have 540 hours on :D



Duck Rogers

[Aerosan]

Duck how is your week-end next? round the 1rst?

[Tailspin]

San and Duck

I am close to you guys in location so if you need a hand shout i have all sorts of calculations and stuff on reduction drives and belts so give me a shout of you need an extra pair of hands.

[Duck Rogers]

....I have all sorts of calculations and stuff on reduction drives and belts....

Much appreciated

.....give me a shout of you need an extra pair of hands..

Cool...now we don't have to tie it to a brick anymore

Duck Rogers

[Morph]

I have 540 hours on this unit.....

Is this the same êrrie you have 540 hours on :D



Duck Rogers

No, mine is AUK, but BOM belongs to my hangar mate and flying buddy. It also has over 500 hours on it

[Tailspin]

Cool...now we don't have to tie it to a brick anymore

HEY only my wife can call me a rock [/quote]

[Morph]

BTW, my belt system does not generate much heat. After flying the belt is still cool enough to be safely touched.

[Aerosan]

Guys Thanx for all the help, Tailspin yes Ill like to exchange some ideas with you maybe I should have done that before I went and spen R5300 on a drive!! But I think it will be OK

Thanx again
P.s. Duck Ill phone you
San