Cheetah cruise speeds

[Big Al]

Hello Cheetah owners.

Just curious. I am purchasing a cheetah with 80hp rotax. If cruise speed is 90mph at sea level MAUW what could i expect the TAS to be at say 5000' I should probably know the answer but i have just started my PPL and there is nothing like good info from an old salt

[Wargames]

if CAS/RAS 90mph, TAS would be 97mph. ISA conditions used for calculations.

Regards,

[flybynite]

Hi Al

My Cheetah has a 11 mph speed difference between mauw and flying solo with 40l (roughly half tank) of fuel. The Cheetah 582 likes cruising between 70-80 mph and the 912 cruises well at 80-85 mph!

Regards

Larry

[John Boucher]

It seems Stephan van Tonder is the oke to ask this one....

My Cheetah(582, P-Prop, 3950 - 5800ft) cruises happily at 70-75mph. When working out a cross country nav I block it at 65knots ground speed!

[Stephan van Tonder]

The one we use in the school is a 912s with a piet de necker prop. Cruises 90/95 mph at 4900 rpm at close to mauw.

[Big Al]

thanks for the info. I am buying the 912 with 3 blade warpdrive prop. How could i increase cruising speed other than fitting a merlin jet motor?

[johnsa]

jabi 3300 might do the trick 120 bhp?

[flybynite]

Hi Allan

Be very wary - for every positive there is a negative -if you start increasing the speed you will loose lift! Your Cheetah is only the 80 hp version - if it had the 912 uls you could have made a plan to get a bit of both worlds. (Remember the short grass strip that you and your boet wants to fly from?)

Regards

Larry

[johnsa]

Why you loose lift?

Hi Allan

Be very wary - for every positive there is a negative -if you start increasing the speed you will loose lift! Your Cheetah is only the 80 hp version - if it had the 912 uls you could have made a plan to get a bit of both worlds. (Remember the short grass strip that you and your boet wants to fly from?)

Regards

Larry

[flybynite]

Apologies - not lift but climb performance. (i am a van der Merwe - not a rooinek )

By fiddling with the pitch of the prop you will either gain speed or climb performance (not both unless you have lots of spare ponies) - a friend nearby tried it with his Cheetah.

Regards

Larry

[Big Al]

Hey Larry

Good to meet you at last 46 years old and never too old to learn I am going to ask many more questions, i will try and tire them at Avstar, give you a break!!

Allan

[johnsa]

Avstar

[flybynite]

Avstar is a flying school in Pmb where Allan is going to do his ppl.

[johnsa]

Is it a good school?

[Big Al]

Hi johnsa

Havent started training with them yet but they seem like a helpful enthusiastic bunch