Author Topic: Engine Rev Up on the ground but not in the air, why? (Read 841 times)

Martin Quartim · « **on:** March 14, 2007, 06:03:50 PM »

I have been flying a Pathfinder with an Enya 45 6001 and so far I am happy with this combo. The engine is very constant and starts one or two flips.

But there is one thing that puzzles me. I start the engine and set it around 8200rpms using a 12x6 TF PowerPoint prop. While on the ground, if I point the nose up the engine will rev up strongly. But when flying the RPM seems not to change at all when nose goes up or when maneuvering.

So my question is why it doesn't rev-up during flight?

I use 7,5% Nitro with 22% lube (50/50 synt.-castor) OS F or Enya 3 plug, 4,5oz Brodak Uniflow tank.

Martin

phil c · « **Reply #1 on:** March 14, 2007, 06:42:03 PM »

'cause you got everything just right for a perfect run with the 6001. If you want(or need) it to break into a 2 cycle like a Fox you will have to start fiddling with things- more compression, more nitro, larger venturi, larger prop, etc. Just the opposite of every thing you've ever read on how to tame an FP 40 that runs away.

Joey Mathison 9806 · « **Reply #2 on:** March 14, 2007, 08:14:10 PM »

air speed may be the differance.air raming up the uniflow tube pressurizing the tank. that is my guess but i am just a piddel flyer and really dont know that much about them.

Alan Hahn · « **Reply #3 on:** March 14, 2007, 09:52:16 PM »

The static prop load is larger than the load the engine sees in flight (see my post in Electric Super Clown thread in the Electric forum--where I plot the motor current and rpm thru a pattern). Also the cooling is less. When you pull the nose up, the mixture leans, and I am guessing now that that puts the engine over the edge.
In flight the prop load is less, the cooling is greater, so even when the nose goes up, and the mixture leans, the better cooling and lower prop load keeps the engine from going into a lean 2 stroke.

Martin Quartim · « **Reply #4 on:** March 15, 2007, 07:50:28 PM »

Thanks for the replies, I have learned a few things here that I thought it was the opposite. I was thinking that perhaps the 12x6 was too much prop and the Enya didn't the have power to rev it up.

I did notice that if I launch at lower RPMs then it does a 4-2-4 but line tension is no good and plane flies too slow.

What props would you recommend me to try next?

Martin

Manuel Cortes · « **Reply #5 on:** March 17, 2007, 02:06:02 PM »

Hello all.
In profile models, If the tank is too wide, centrifugal force (in flight, not on the ground!!!!) will cause the engine to lean substantially, changing the setting.
Try to install a "tall" tank, so the feed pipe will not so far from the NVA "flight path".
Hope it helps.
Regards.
Manuel.

Russell Shaffer · « **Reply #6 on:** March 17, 2007, 06:59:16 PM »

That is a very good point, Manuel. I have been having some trouble with a "tall" tank. I'll try your suggestion. Thank you.

Martin Quartim · « **Reply #7 on:** March 19, 2007, 05:51:09 AM »

Quote from: Manuel Cortes on March 17, 2007, 02:06:02 PM

Hello all.
In profile models, If the tank is too wide, centrifugal force (in flight, not on the ground!!!!) will cause the engine to lean substantially, changing the setting.
Try to install a "tall" tank, so the feed pipe will not so far from the NVA "flight path".
Hope it helps.
Regards.
Manuel.

Hi Manuel,

the first tank I had was the 2" Wide Wedge and then I replaced with the Medium Wedge 13/4" and it did improve the engine run, and is the tank I am using for now. This is the narrowest tank I have found with 4.5Oz.

Do you think a Plastic R/C tank with clung would work better?

Martin

Author Topic: Engine Rev Up on the ground but not in the air, why? (Read 841 times)

Martin Quartim

Engine Rev Up on the ground but not in the air, why?

phil c

Re: Engine Rev Up on the ground but not in the air, why?

Joey Mathison 9806

Re: Engine Rev Up on the ground but not in the air, why?

Alan Hahn

Re: Engine Rev Up on the ground but not in the air, why?

Martin Quartim

Re: Engine Rev Up on the ground but not in the air, why?

Manuel Cortes

Re: Engine Rev Up on the ground but not in the air, why?

Russell Shaffer

Re: Engine Rev Up on the ground but not in the air, why?

Martin Quartim

Re: Engine Rev Up on the ground but not in the air, why?