How much time left?

Hi all,

I'm not new to flying, it's just that I fly electric mostly. I now have a friend's PT-40 ready to go. The engine problem is fixed I spoke about earlier now I'm just wondering how much time should I expect on an 8oz tank of fuel flying an OS 40fx. I know I can just time it, but don't want to risk it. I know I can get 12 minutes on a 900ma battery. Can I expect at least that with this engine? Thank in advance.

Darren

Reply to
Darren Earle
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Reply to
jflongworth

That answer is dead on, but I'd like to add that you aren't going to notice a big difference between full throttle and half in level flight. Full power is only needed for climb and aerobatics. I normally fly mine

15 to 20 minutes before bringing it in, and there's always 2 ounces or more left. I don't bother with a timer, since I use this for teaching. When I cover what I wanted to cover that flight, we bring it in. Try a 10*5 or an 11*4 prop on the plane. It will help keep the speed more constant and need less trim changes than a 10*6.

The way to trim the elevator on this one is for level flight at half throttle. Then you use the throttle to control the altitude, and don't mess with the elevator trim. If it dives excessively when you drop the power, and noses up too much when you give it power, you are too nose heavy.

Reply to
John Alt

Hi Darren,

What I do on each of my models is to time how long it takes my electric fuel pump takes to fill the tank from empty. I then fly for

10 mins or so then I land and time how long it takes to top off the part empty tank. Then it's just a simple one off calculation to work out the typical max flying time. Be a bit conservative to allow a saftey margin and you'll be just fine. Of course you must fly in a similar style on the test flight to the subsequent flights but if you do the method works very well.

Nick

Reply to
Nick Lambert

I haven't read every post in this thread but the phrase "but don't want to risk it" struck me funny. If you mean risking a dead stick landing when running out of fuel, so what? With a PT-40 I don't imagine you're hovering at 6 feet of altitude, where a flame out could cause damage.

Try practicing simulated dead stick landings if that is your fear. It's preferrable to land with the motor running, but landing dead stick shouldn't mean the model will necessarily be damaged.

Mike

Reply to
Mike

Thanks for all your advice. BTW, Mike I did mean a dead stick landing. I just didn't want to be too far out from the landing strip.

You've all been helpful.

Darren

Reply to
Darren Earle

Darren,

I hope no offense to your flying style or experience was taken, as none was meant.

My mention of practicing dead stick landings of course can be done without actually shutting off the engine. Simply pull the trottle back and try to get back to the runway. Flame outs will happen even when plenty of fuel is left as you probably know. Best thing to remember is don't quit flying the model even if you can't make the runway.

I've watched flyers 'grease' dead stick landings who hardly ever grease one when the engine is still running.

Mike

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Reply to
Mike

I don't remember you ever watching me land!!! :-) This is very true with flyers of Telemasters, Kadets and other big floaters!

-- Morris Lee snipped-for-privacy@verizon.net

Reply to
Morris Lee

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