Flight time? - Stratus / New tank.

[Aviation addict]

Guys,

Does 9 mins at 1850 rpm sound about right for a Stratus (with the new tank)? I'm using the 91SZ-H (pumped).

Have my Mid needle closed and High at 1 turn open by the way and am using 20% Magnum. I think I could still be a bit rich.

[DavidH]

Well the new tank holds 20 ozs. So that would mean your using over 2 ozs a minute. That sounds a little on the high side to me. You should be in the range of about 1.5 to 1.75 ounces used per minute. I would think in the 11 -13 minute range.

David

[Aviation addict]

Thanks David.

Its my first 90, and I've only just got it to run smoothly - but I thought 9 mins, especially with the new tank was a bit short. I suspect I'm running it a bit rich.

With the Mid closed, the most I've wound the High in previously was to 3/4 - where it didn't sound lean doing a full throttle climb out - but not having enough experience in tuning I dared not go below 3/4 and backed it off to 1 turn.

Knowone at my club has experience of the SZ so I'm on my own from that point of view.

I haven't heard the engine sound lean during climb out so far - but I'm sure if I keep reducing from 3/4 I will at some point. Then I gather that I need to click in 'throttle hold' and see it the engine comes straight down to idle or whether it takes several seconds to some back in the revs. If it's 'lean' I understand it will hesitate to come back on the rev's and in this situation I need to richen the 'High' a couple of clicks - go fly the machine, and repeat the process?

[DavidH]

John,
90 size engines are fuel thirsty. The power has to be supplied by an object. That object would be fuel. A gallon of fuel may get you an hour of flying time. That would be 6 tanks at about 10 mins each.

Welcome to 90 size helis.

David

[Aviation addict]

Hi David,

Don't get me wrong, I get through a mountain of fuel each year and am more than happy to do so. I just wondered what I should be getting to double check my efforts at engine tuning.

Its looking like 10 mins now (with constant flying - no Autos) so I think I've got it about right.