Turboprop130

Hi guys, my extra 300 is flying fine upright and inverted. Also, fine while going vertical. When I dive the motor stalls and I'm pretty sure it's from air being sucked in through the fuel clunk. My clunk is close to the back of the tank but not touching and moves back and forth freely. It appears the clunk is not falling over backwards enough when the plane is in the diving position. Is it possible to use a in-tank T coupling with dual clunks or should I shorten the pick-up tube to allow it to fold over more? Your suggestions would be greatly appreciated,

jetmech05

If you shorten the line the clunk is on then you loose useable fuel in your tank......If you use two clunks and go in a dive then one clunk sucks air even if the engine continues to run you have really leaned out the mixture.....lastly you don't want the clunk folding back on itself.....it may not straighten out which is a problem in itself.....
Are you doing long power on dives? If so there is your problem....power back on the down line..as fuel does go to the front of the tank in a dive...
I was at Kadena 79 to 81 over on the Navy side.....the Marine Corps had a T-39G for rapid VIP transport....that was my airplane....crewed it and fixed it.....

David Bathe

Are you throttling back?
If you throttle back, there is enough fuel in the line to last many, many seconds before you'll be sucking air. And most would believe that the fuel is pushed to the back of the tank during a vertical drop anyway. What I wouldn't bother with is the flexible clunk line jive. Been there done that... just get tangled up. Your problem lays somewhere else.
It's an easy job to try to find answers. Ground run the engine, hold he nose vertical as one would to check if it's going lean, then hold the nose down. See what the engine does, leaning, riching etc.
As stated, it should run for a surprizingly long time.

Lnewqban

TP130:

Check this thread related to yours, which shows a good video that explains the problem:

http://www.rcuniverse.com/forum/m_89...tm.htm#8924271

Regards!

jester_s1

If throttling back doesn't help, you can run a hopper tank. It's a second small tank (2oz usually) between your main tank and your engine. The pickup is rigid and ends in the middle, so any bubbles that make it to the hopper tank won't get picked up.

jaka

Hi!
I can assure you that a properly setup tank will not give this symptom!
You must be doing something wrong!
Remember that the clunk should not fall forward in a dive!
No special fuel hose size is needed!


Set the high speed needle by holding the airplane nose straight up and set the needle a little rich.
Set the idle needle correct so that the engine throttles well and gives instant respons!

Use a Uni-flow tank set-up (two clunks) in proper size ie 240cc (8oz) for a 6,5cc (.40 ) engine.
Use 5-10% nitro!
use good glow sport plug (OS 8 or Enya 3 )
Use a suitable prop ie 10x6-12x4 for a 6,5cc (.40) engine.

Gray Beard

My Feedback: (-1)

I watched that video once, really an eye opener.
It just sounds like you are out of tune and over thinking the problem. Set up your engine like Jaka said and when it is in correct tune I bet your problem will go away.
Jaka, A two line tank?? Is the Uni Flow a bladder tank?

andrew66

The uniflow setup has a clunk on the pressure line. I always have the pressure line a bit shorter so the other line doesnt pick up air bubles. It provides a more uniform fuel flow, and the engine doesnt lean out as much (if any at all) towards the bottom part of the tank. I tried it on my kadet, and that is the only setup i will use.
The uniflow uses a regular fuel tank

Ed Smith

The best tank of all is the bladder tank. I use them in all of my aircraft. They solve all sorts of fuel supply problems. For Pylon Racing we use two line bladder tanks and use a syringe to empty and fill them. For general sport flying I use the "Tettra" brand of tank. I set it up as the instructions on the box show as a three line tank. A syringe is not needed to fill the three line set-up. The filling procedure is no different from any other three line tank. I use an ordinary Du-Bro pump.

Ed S

Turboprop130

Thanks for all the replies. I'm going to rebuild the tank and look for any problems. I'm also going to make the fuel line a few inches longer so it can hold more fuel.