Nobler(ARF),MAGNUM 36,Tank problem

[Leester]

I went flying today and my Fox 35 Ringmaster was great as usual always a perfect engine run. My Magnum 25 powered Tomahawk is an absolute blast. The 25 has such a sweet break to it I just love it. Then came my ARF Nobler Magnum XL 36, this is my 4 attempt to fly it. Tall grass snaged the Landing gear first time on take off. #2 tall weeds snaged the lines. #3 engine got hot on the ground and shut off. I went from 10/22 50/50 to 10/25 all castor,  opened up more vent areas I made them big. First attempt today got hot and shut off, so I took the tongue muffler off. I let it cool filled the tank and right away it flooded, couldn't move the prop, I took off the plug and drained. Started it and it ran fine on the ground as soon as I got it airbourn it went rich the hole flight then leaned  and rich back and forth then leaned and next lap ran out of fuel. When I refueled it still had 1/2 to 1oz left. It's a clunk tank I even capped the overflow but did't change anything. My third flight While landing caved in the landing gear, luckely no other damage. Am using an 11-4 prop Randy Smith venturi PA needle Thunderbolt 115493 plug. What did I not do???  Thanks  Oh by the way even flying slow it flys fantastic and looks great.

[Bill Little]

Make sure their is enough opening for the air to exit the cowl.  inlet size is important, but maybe not as important as having the exits big enough and located where the air can get out.  At last twice as much exhaust opening as inlet is needed.  For lack of a better term, a "venturi effect" is created if cooling holes are done properly.

Also recheck ALL the plumbing on the fuel system, and tank.

Bill <><

[Leester]

Bill : My outlet hole is 1 1/2" wide by 3" long and starts 1/8" before the glow plug the inlet is 1" diameter. Since it didn't get hot after I removed the tongue muffler I'm guessing that might have been it??? I'll recheck the tank plumbing and see what I come up with.

[Leester]

Just so I have this right with the engine inverted the fuel line from the tank to the engine should be on the same level correct?

[Bill Little]

Pretty much so, but it can go up and down on it's way to the engine from the tank with out causing problems it seems.  What the engine/tank set up is looking for is a fuel draw that is consistent for upright/inverted/manuevering flight.  NVA position is not as critical as many seem to think.

Case in point is the "Stock" ST G51 with it's NVA set up over the top of the case in the add on venturi.  I have seen an experiment where the same engine was run (inverted mounted) in a conventional lay out and with the stock set up.......... no changes were needed in tank shimming!  I saw the explanation once sometime back, but I don't recall the specifics, and many won't accept it anyway even though it is the truth.

Bill <><

[Leester]

Well repairs are complete. The landing gear mount basically just came unglued as no wood was attached except some balsa from the fusalage sides, so I epoxyed the sh*& out of it. I found 2 things on the tank, The feed line to the engine was about 3/8" higher than the spray bar and the vent inside the tank was about an inch or more from the top. So I've got the feed line in line with the spray bar and the vent is about 1/8" from the top now. Now it's up to the weather man as I really want to fly it at full speed. I also want to fly that Tomahawk. Thanks for the help.