Any one know how match Gear box ratios with prop size & pitch ?

[Doug Evans]

how do u work out the best suited Gear box ratio & prop size & pitch too gain the best climb & cruicse for a given hp & air craft type "Lightwng "

 

is there anyone that know that stuff ?

 

EG

 

C type

 

3 to 1 ratio suit a 72 '' prop with 65 hp rotax what will that give

 

climb or speed ?

 

Cheer Doug

 

 

[fly_tornado]

have you tried asking another Lightwing owner or the factory?

 

 

[Doug Evans]

yes

 

 

[fly_tornado]

what did they say?

 

 

[RickH]

Hey Doug

 

From memory the 582 rotax redlines at 6800 rpm 3:1 ratio means 2266 max prop rpm you should set the pitch of the prop so that with the Bird tied down and max throttle the engine will develope about 6400 max rpm this should allow it to reach 6800 when on the move.

 

This means the prop is running at max efficiency for that engine prop combination .

 

If you set the prop pitch finer than this (similar to low gear in a car) you will get better take off preformance but you risk an engine overspeed (not good) if you set prop to a courser pitch (high gear) the bird will Theoretically cruise faster but the engine will not develope it's full h.p.( also not good)

 

Hope this is helpfull to you.

 

Regards RickH

 

 

[Doug Evans]

Thanks Rick

 

I was advised by rotax too run the 2.62 ratio C type so that what I end up with , my old lightwing ran 3.1 C type with a 3 blade 68" warpdrive

 

Not shore what prop I run yet I have a 2 blade 68 " lightwing prop I will try but most likely run a 2 blade ground adjustable in the future if the old lightwing one dose not work ....

 

 

[RickH]

Doug

 

My boss has an X_Air running a 582rotax with 68 inch brolga prop 3 blade which I often fly,runs damn fine.

 

Regards Rick

 

 

[robinsm]

currently running Xair Standard 582 blue head. c box 3:1 Brolga 68 inch 16 degrees pitch. Runs beautifully.

 

 

[Doug Evans]

thank fellows for your input