Sig KING KOBRA help.
08-07-2007, 12:41 PM
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Sig KING KOBRA help.
Almost done with our clubs half built hangar queen king Kobra. Its been passed around for 7 years now its almost done. My question is fuel tank size. I have a 11oz and a 14oz. For an engine I am using a evo .61. The 14oz fits but it touches the aircraft on the top and bottom of the tank, will this cause any problems and is 14oz of fuel to much weight? Also does anyone know of a perfered CG or Throws other that the recomended setting and CG. Do you think the plane will be fast on the evo .61. I fly a little .25 size cobra and its great can't to fly this one
08-07-2007, 01:41 PM
#2
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RE: Sig KING KOBRA help.
I would be worried about the fuel foaming with the larger tank touching the fuselage the way you describe. I always have my tanks wrapped in foam to try and cushion them a little bit. As the fuel level goes down in the larger tank it may begin to foam, you could end up with a dead stick after some aerobatics due to the momentary loss of liquid fuel.
I'm about to start a King Kobra as well - post some pics of yours. I've flown the small Kobra for a couple of years now. Currently you can see it in the Crash and Rebuild forum under Kobra Krash. Making a few mods during the re-build. Hopefully will see the sky in a few weeks.
Dan
I'm about to start a King Kobra as well - post some pics of yours. I've flown the small Kobra for a couple of years now. Currently you can see it in the Crash and Rebuild forum under Kobra Krash. Making a few mods during the re-build. Hopefully will see the sky in a few weeks.
Dan
08-07-2007, 02:09 PM
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RE: Sig KING KOBRA help.
Igree about wraping with foam. I think I am going to install the 11oz tank. I like a long flying plane, for a battery I installed a 6v 2500mah pack. I also used two micro high torque servos I think they are tower TS-53 side by side in the wing for flaperon mixing. The little kobra is great one of my favorite planes love the way it lands, as soon as the wheels touch it just seems to get sucked to the runway. What are you going to put in your king kobra? I did not mount my engine at that odd 45deg I mounted it 90 deg just like the great planes patriot. Makes imstalling the tuned pipe easier. Good luck I will post pics when I am done
08-07-2007, 02:54 PM
#4
RE: Sig KING KOBRA help.
i have installed a 14 oz tank in my KK. i layered an additional strip of 1/2" x 1/8" balsa from just behind the firewall down the sides of the fuselage until i was far enough back to remove the tank. i tapered the ends of the strips to flush with the fuselage, sheeted the top and sanded the slopes until it was barely noticeable. now i have a little bit more room for the foam around the tank.
david
david
08-07-2007, 05:13 PM
#5
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RE: Sig KING KOBRA help.
I'm still not decided on an engine. I've been working on the Kobra and have a YA F18 Hornet on the building board too. The King purchase was one of those late nights on the web and before I know it I have the credit card out placing an order. I built one back in 94' but sold it before I ever got one flight on it. Are you putting retracts in yours??
Dan
Dan
08-07-2007, 05:53 PM
#6
RE: Sig KING KOBRA help.
i put out an inquiry in the classic pattern flying forum asking if there were any KK builds going on. it has turned into a build thread somewhat. i am happy to see other threads starting on this plane. always helps to share ideas.
08-08-2007, 05:07 AM
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RE: Sig KING KOBRA help.
No retracts I am way to cheap for that! I hope that the older kits stay in production. It seems that the older planes fly better? I don't know if anyone else feels that way? But for me my top flite contender and my little kobra are just great flying planes.
08-08-2007, 06:24 AM
#8
RE: Sig KING KOBRA help.
i've got a Mark/Moki .61 with a tuned pipe going on mine. and i am installing spring air retracts. i have put some mid project photos over on the classic pattern flying forum.
08-08-2007, 11:30 AM
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RE: Sig KING KOBRA help.
ORIGINAL: SPLIT S
I would be worried about the fuel foaming with the larger tank touching the fuselage the way you describe. I always have my tanks wrapped in foam to try and cushion them a little bit. As the fuel level goes down in the larger tank it may begin to foam, you could end up with a dead stick after some aerobatics due to the momentary loss of liquid fuel.
I'm about to start a King Kobra as well - post some pics of yours. I've flown the small Kobra for a couple of years now. Currently you can see it in the Crash and Rebuild forum under Kobra Krash. Making a few mods during the re-build. Hopefully will see the sky in a few weeks.
Dan
I would be worried about the fuel foaming with the larger tank touching the fuselage the way you describe. I always have my tanks wrapped in foam to try and cushion them a little bit. As the fuel level goes down in the larger tank it may begin to foam, you could end up with a dead stick after some aerobatics due to the momentary loss of liquid fuel.
I'm about to start a King Kobra as well - post some pics of yours. I've flown the small Kobra for a couple of years now. Currently you can see it in the Crash and Rebuild forum under Kobra Krash. Making a few mods during the re-build. Hopefully will see the sky in a few weeks.
Dan
08-08-2007, 12:57 PM
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RE: Sig KING KOBRA help.
I was able to put foam on the sides the bottom is touching do you think that would be okay?, I am using a sullivan flexi tank they seem less prone to foaming up. I have never heard of the WD-40 in the tank? I might try it thanks for the tip.
08-08-2007, 03:31 PM
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RE: Sig KING KOBRA help.
I had wing dowel touch a tank once. The tank was, otherwise, insolated from vibration. Not only did it jossle the tank to point where the engine wouldn't run properly, it also nearly ground a hole through the tank wall (Sullivan non-flex tank) before I diagnosed the problem. It got worse over time as the rounded tip of the dowel slowly but surely ground a nice little pocket into the tank in which it could firmly rest. It got to point where the engine would abruptly quit even on the ground before I finally figured out what was happening.
I have a King Kobra sitting on my ever growing some-day-if-I-ever-have-time kit stack.
I have a King Kobra sitting on my ever growing some-day-if-I-ever-have-time kit stack.
08-09-2007, 07:38 AM
#14
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RE: Sig KING KOBRA help.
My experience indicates that if the tank touches wood the fuel will foam. Foaming is always intermittent and varies with the speed of the engine. Snake oils are not a cure.
Why risk the airplane to a snake oil solution? Solving the problem seems like a much better approach.
Bill
Why risk the airplane to a snake oil solution? Solving the problem seems like a much better approach.
Bill
08-10-2007, 02:48 PM
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RE: Sig KING KOBRA help.
Hi!
Use a Tettra "Bubbless" tank and you will have no problems with fuel foaming.
Or use the well proven Uni-flow metod when installing the 14 oz tank (The size you should use).
Use a Tettra "Bubbless" tank and you will have no problems with fuel foaming.
Or use the well proven Uni-flow metod when installing the 14 oz tank (The size you should use).
08-10-2007, 09:13 PM
#17
RE: Sig KING KOBRA help.
looks great, more photos? let us know how it flies. also, what is it's overall weight? i plan on a moki .61 in mine. good luck with the maiden flight.
