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Thunder Power RC . Mikado Modellhubschrauber . GrandRC

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Gasser Model RC Helicopters > Inverted Cut-Out?????
 
 
DangerousDick
Veteran
Location: Cheshire, England

OK then, I've sorted out my throttle by using the GV-1 - which works as 'sweet as a nut' and I'm having a bit of fun with my X-Cell today.

Hovering was fine so into some circuits and still perfect so onto some stall turns - still fine, up high to try a loop and OH MY GOD!!!!!!

On the inverted part of the loop the engine dies and I'm in my first inverted auto - managed to get some + pitch to spin the blades before I flipped it round and landed it on the field.

Now to see if it would do it again (am I mad???) so even higher this time and better positioned just in case and I attemtped the same thing and sure enough it quit at the top of the loop.

I got it down and finished the tank off just practising auto's - even through the weight of this thing, it auto's really nicely and I was almost starting to get bored with the easiness of the excersise .

Now I've checked the GV-1 settings and they are fine - I've shaken the tank around to make sure the clunk isn't stuck somewhere and that looks to be OK so apart from ripping the fuel lines to peices both inside the tank and out I'm lost for ideas. This is my first gasser and I'm not really sure which needle to 'play' with and which way to turn it .

Any ideas from you experienced lot would be great though - I'm starting to really like this heli but if I can't fly it upside down then I'm not going to find much use for it .

Cheers
Richard.
06-21-2003 Over year old.
 
 
Billme
Key Veteran
Location: MS

You need to get you a weedeater type clunk I use a Stens 610-381 over here...You want to use a small 1/8 tygon fuel line, and have it long enough so as the it loops on the otherside of the tank, with the clunk resting flat, midway in the tank....
This should take care of your problem..I've done a few autos like that myself, til I figured out a reg clunk like the glows use don't work


Good luck,
Bill
06-21-2003 Over year old.
 
 
DangerousDick
Veteran
Location: Cheshire, England

Thanks Tom, yep I got me a V curve though the Govenor was taking care of all that

OK then Bill, I've never heard of a 'Weedeater' type clunk - is that the official name for it, or am I going to get laughed out of the hobby store when I ask for one

I've turned the thing upside down and I can hear the clunk hit the top of the tank but I haven't yet taken the line out to see what's inside.
06-21-2003 Over year old.
 
 
SteveH
rrProfessor
Location: Texas

Richard,

Bill is right. I had the same problem and he told me to do the same thing at the Louisiana fun fly, I did it, and problem solved. Go to a lawn mower/weedeater repair shop to get the clunk and the line.

SteveH
06-21-2003 Over year old.
 
 
Billme
Key Veteran
Location: MS

You'l have to go to a small engine dealer that repair small 2 cycle engines...Hobby shops don't carry it....Yet They also work good on glow, so if you have bubbles ending up in your header tank, this will keep it from doing it...I let some of my friends try it, and they couldn't believe it...I think I have figured out how it picks-up without getting air, even when the fuel level gets below the top of the clunk...Pretty amazing

Also take note at what Tom said about the fuel line getting stiff...The smaller line will still get stiff, but takes longer because of the lenght, and size...It still needs to be change...every 3 months is a good place to start....The smaller line will also give your carb a better suction for the pump...

Manoman, you should see my Xcell flying now ...Its scary: but looks cool
Many Regards,
Bill
06-21-2003 Over year old.
 
 
Billme
Key Veteran
Location: MS

Sorry Tom,
I meant to say it that way because there are so many different type tanks...On my Xcell, I use the old Dubro tank with the pick-up line going in from the side..The line goes to the other side of the tank, and makes a 180 and back about halfway ...You want to loop it back towards the front of the heli..This way, it can travel better, and can reach more area in the tank...The important thing here is that its able to lay flat...When I say loop, I mean a half loop 180...This is what works for me...Most folks don't pay attention to this, but you can experiment with different lenghts, for different tanks to get the best results ...This just happen to be good for my dubro tank...
I'm thinking real strong about upgrading to the SE frontend, with the bigger tank, since my setup burns more fuel...This 231 is really drinking fuel right now til the ring seats.. Whats so great about this engine is how it performs in this heat...It has not even hinted to bogging with the 720s...Oh gosh, I'm rambling again...getting old sucks
If this does't make it clear, let me know, and I'll try something else...I'm not that good about getting my thoughts to the mouth, or the keyboard anymore
Regards,
Bill
06-22-2003 Over year old.
 
 
Al Magaloff
rrMaster
Location: 12,199 Posts- Enough Time Wasted. See Ya!

Bill, can you describe the Stens clunk. Is this the one with the felt all the way around, or the black cage with nylon screen, and the weighted bottom?
06-22-2003 Over year old.
 
 
Billme
Key Veteran
Location: MS

I'll see if I can get a picture Al...It looks just like the felt robbe type, except where the felt is, it has a white delrin looking pipe over the cage..

Regards,
Bill
06-22-2003 Over year old.
 
 
Malorie
Elite Veteran
Location: Paw squared, MI

It is also possible that your low needle is set to lean. When you go to negative pitch from positive at the top of the loop the throttle goes quickly from the high needle to the low and back again. If the low needle is lean, the motor will not have enough fuel to recover to the high needle and will die.

Life's a journey, NOT a destination.
06-22-2003 Over year old.
 
 
ddavison
Veteran
Location: Brownsville, Pennsylvania

I think that was the problem I had, some time when doing rolls or loops the engine would cutout like it took a air bubble, it would not quit just like a hiccup, enough to get you attention. I went through all the fuel supply stuff, changed tank, clunk, lines, filter, etc. Even changed carbs. Just when you think it had quit doing it, hiccup again. Finally two weeks ago after fiddling with the needles it has quit and is running steady in all attitudes. (Xcell Gas, Z23 with Bloise head,governor, 1750rpm, 603 carb, Amsoil 64/1 mix,coleman fuel, changing back to gas this week)

DaveDavison, Miniature Aircraft Field Rep. Spectra,Stratus,Furion, JR 12x 2,4
06-23-2003 Over year old.
 
 
Billme
Key Veteran
Location: MS

You guys are right, that can happen...I answered based on he said that it went dead (I took it as quick) Useually it will just hiccup, like you say, but want quit, if it is to lean

While I'm at it, you can have a perfectly tune gasser and do great for straight, and level flight. But, once you put more load (hard turn) and don't have throttle mixing, or a Gov, the engine will heat up quick, and lean out...It will happen even faster using the camper fuel...

Dave, why are you going back to gas? Just wondering

Regards,
Bill
06-23-2003 Over year old.
 
 
ddavison
Veteran
Location: Brownsville, Pennsylvania

Just want to try gas again to see if any diff. I don't mind the smell. Having a little hard starting problem now. Have to open the throttle too much to start.

DaveDavison, Miniature Aircraft Field Rep. Spectra,Stratus,Furion, JR 12x 2,4
06-23-2003 Over year old.
 
 
Billme
Key Veteran
Location: MS

You got something not right then...I'm breaking in this 231 on camper fuel., on the first crank of the day, it starts on the third pull.. After that, the first or second...
Let us know if the gas change corrects your problem.

Regards,
Bill
06-23-2003 Over year old.
 
 
rbort
Elite Veteran
Location: Franklin, MA - U.S.A.

Richen the low end just a tiny bit

Hi Richard:

Just richen the low end enough to feel it move and retry the loop. If it is too lean, it will cause the inverted cutout. Do it a little at a time until the quitting stops.

My heli uses the stock 10oz Dubro tank, has old stiff tygon fuel tubing in there with the stock clunk, got 953 flights on the ship, and it never quits even as I tumble roll and loop it all day long. I did have the engine cutout and come back before (many flights ago), and it was due to the low mixture being too lean. Malorie is right, go with her and me.

I don't want to say don't use the felt clunk or loop the line in the tank, only that I personally find that to be unnecessary. The 10oz tank is enough for a 25 minute flight, and, if you fly it for 15 minutes and 3d it, you will land with fuel just above the "hump" on the tank which will be high enough to prevent sucking any air and causing any issues. Of couse if you fly longer and the tank gets much lower than that, then you will have to either use a header tank or try the felt clunk. For me 15 minutes is long enough and with the fuel level so high in the tank I find no audible engine issues due to sucking air.

Good luck and enjoy!

-=>Raja.

1005 Xcell Gas, BHH G26 3D Plus, Jewel Generator
Spectra-g, BHH G26 3D Plus, Jewel Generator
06-24-2003 Over year old.
 
 
Billme
Key Veteran
Location: MS

Raja,
I don't recommend using the felt clunk.. It will fill your first screen full of felt

Regards,
Bill
06-24-2003 Over year old.
 
 
Malorie
Elite Veteran
Location: Paw squared, MI

Just a suggestion, I use an oversized nut as a fuel tubing clamp on my clunk. It holds the fuel tubing on the clunk and adds weight to it so it can flex a shorter stiffer line. Then I use a piece of the black noeprene for a clunk line which is just a bit more flexible. I have tapped the tank on the side so the clunk can reach the four opposite side corners. It can get fuel no matter the attitude (except a sustained left side knife edge).

Life's a journey, NOT a destination.
06-24-2003 Over year old.
 
 
DangerousDick
Veteran
Location: Cheshire, England

Thanks for all the help guys, I managed to get hold of some new fuel tubing today - I got the Large Tygon for all the plumbing outside the tank, and some Medium Tygon for the clunk line (they didn't have any Small ). I also managed to get a clunk 'recommended to reduce foaming' which I was told was compatible with petrol engines.

I've cut the clunk line to length but the clunk itself doesn't really seem heavy enough to swing round all four corners so I think I'll add a nut as Malorie suggested (thanks) to weight it some more. It has lead in, but it's not enough to pull it around.

I certainly got some 'Auto' experience this weekend and it does it really well - especially considering the weight I'm pulling around in this bird .

I'll try 'tweaking' the low end needle also (thanks Raja) to see if that makes it better still.

Cheers
Richard.
06-24-2003 Over year old.
 
 
Billme
Key Veteran
Location: MS

Rusty McClintock is suppose to upload some pictures of the pickup I use...Hopefully it will be soon
Bill
06-25-2003 Over year old.
 
 
DangerousDick
Veteran
Location: Cheshire, England

Aaaaarrrrgggghhhhhhhh.....

Re-plumbed all the lines, fitted 'felt' clunk (even added weight in the form of a nut) and spent all day playing with mixtures but still I get a cut when inverted.

I'm waiting for some 'small' fuel line - should be here next week sometime, the smallest line I could get locally was the 'medium' Tygon stuff.

I think I'll take the main drive gear out, start it and turn it over 'on the bench' to see if I can spot anything .

Has anyone got a 'Header Tank' setup on one of these things?

I'm pretty sure it's fuel related, is there anything in the engine which could cause 'starvation' when in certain attitudes?

I really don't want this one to beat me !!!
06-28-2003 Over year old.
 
 
ddavison
Veteran
Location: Brownsville, Pennsylvania

Changed back to gas today, motor started easier, running better now,sounds happier if you know what I mean. all attitudes nice consistant run. No cut out when inverted. Did not touch the needles, going to put a little more top end pitch in tomorrow. Before changing back to gas,had a half tank camper fuel to use, engine sounded a little off, at end, after auto it would not accelerate from idle. Just changed to gas, OK now.

DaveDavison, Miniature Aircraft Field Rep. Spectra,Stratus,Furion, JR 12x 2,4
06-28-2003 Over year old.
 
 
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Gasser Model RC Helicopters > Inverted Cut-Out?????
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