TOYMAKER

My Feedback: (6)

If some of you are searching for that last ounce or two to get under 11lbs just before the NATS here is CHEAP solution that might help.

Now I cant take credit for this as I got the idea from B.W Ponder and Todd Blose as this is what they had to do at the last minute at last years NATS to make weight.

This is a Coke bottle fuel tank. B.W. used his Tetra stopper to fit in the coke bottle opening. I discovered that by using the standard parts of my Du-Bro fuel tank tha I could also make it work. The Coke bottle opening is just too large for the standard stopper so try this.

I used the rubber stopper and the back piece only. I first drilled a small hole exactly in the center of the cap for the tightening screw and lined up the backing plate to drill two 1/8" holes for the fuel lines(see photos). I then used 1/8" aluminum tubing(lighter then brass) and made a straight fuel pickup line and then a longer one for the vent so it would reach to the high spot in the bottle. Assemble like a regular stopper but dont tighten the stopper screw till after you have snugged the cap on the bottle. The standard stopper will expand enough to help seal the aluminum lines and at the seat of the bottle and cap.

Mine only weighted 1.7 ounces (my 20 oz Du-Bro weighed 3.4 oz)and I can inter change between a 16 oz bottle or 20 oz, both weighing about the same.
The photo of the tank in the plane is a Diet Sprite bottle that is about 17 oz and worked just fine.

Wayne Galligan
D6

bubbagates

My Feedback: (32)

Cool idea and I do understand the resons for using it. I do use one for a catch bottle but I do have a question. How would this hold up under long term use and under repeated cycles of "g" loads, pressure from the glow engine, vibration and such?

So I guess what I'm really asking is does somebody use this all the time?

MikeEast

My Feedback: (3)

Yes it will hold up to pressure, stress and strain just like a tetra tank. You can even use your tetra tank stopper on the bottle. Just use a dremel to grind off the 1st couple of threads on the bottle and it will fit right up. aquafina water bottles work great. I think Todd told me BW used a Dr Pepper bottle. Saves about 1.5 ounces! We have put a couple together and they work great.

RCKen

My Feedback: (9)

Will they hold up for use as a smoke fluid tank?

Thanks in advance

Ken

bubbagates

My Feedback: (32)

Thanks BigNed

You guys have me thinking now and just one final question. If I use the correct stopper, will gas be a problem? Ken beat me to the smoke question

TOYMAKER

My Feedback: (6)

Bubba,

I would think it would be OK for gas or smoke provide you use a neoprene stopper. I have had gas in a Coke bottle for quite some time once. It does not appear to affect the mterial of the botte or cap.

I can buy the stopper kits at my LHD so making one does not require wasting a new tank.

Wayne G.

cameron

I seem to remember an article from a british magazine, about jets using coke bottles for pneumatic retract pressure tanks.
Apparently they will fail eventually, as they are designed only to hold 1 cycle of pressure.
Precisely what pressure they were talking about I'm not sure, but ill see if I can dig it up.
Probably wont be a problem under the sort of pressures developed in a model fuel tank, but just thought id let you know.
Seems to have been proven in practice though.

Cameron McDonald

Doug Cronkhite

My Feedback: (34)

Most jets run over 100psi on retracts.. You're never going to see this kind of pressure from a YS I think.

bubbagates

My Feedback: (32)

Thanks guys

I remember reading somewhere a YS runs somewhere around 9psi.

cameron

Thanks, thought that might be the case, just didn't want to see someone blow a fuse apart unnecessarily.
Cam.

MikeEast

My Feedback: (3)

We have discussed the jet retract tanks before while considering these coke bottle tanks, specifically the fact that there have been coke bottle air tanks explode in flight destroying aircraft. As mentioned the pressure is a LOT higher, I dont think that a YS can generate much more pressure than shaking up a hot coke will generate. I would guess that they will at least last a season if not several seasons, but its simple and cheap to go buy a bottle of water, drink it and change out tanks as often as you like. Especially if you use Waynes technique and just screw on a new tank!

Mike E

flywilly

My Feedback: (121)

I think YS pressurization is on the order of 6-10 psi.

klhoard

My Feedback: (10)

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Saving an ounce?. . . I'm thinking of saving $12!!!!
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And a couple ounces!!!
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MikeEast

My Feedback: (3)

Hey Keith,
This is Mike East. We met in Pensacola the weekend the contest rained out. I wouldnt have known it was you had I not seen your plane in your avatar AND your plane on the cover of the K Factor. I Enjoyed our dinner at that Irish pub down near the coast. Did you guys ever get to fly a contest in Pensacola?

Mike

MTK

Wayne and all, a couple of notes on the plastic Coke bottles:

This type of container is made of a 3-layer PET, a type of plastic that is much tougher than the typical blow-molded polyethylene container used as tank material in RC. The toughness allows for very thin walls and the multi-layers provide specific resistance to CO2 permeation, which could cause the Coke to become stale. The bottles are not rated for 100 psig of air pressure by any stretch, unless reinforement was used, and there goes the weight savings. But can easily withstand the 8 psi a YS puts out.

There is only a very minor concern about leaving the bottle exposed to sun which could degrade fuel performance and could sensitize the fuel. But enclosed in a fuse, there is no such concern. Like I said, it's very minor.

MattK

Eric.Henderson

If you don't take saving weight seriously, this could happen to....


(Bobby Satalino being a good sport, as always, to bring us this humor)

Regards,

Evl-Eric.

klhoard

My Feedback: (10)

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Hey!! How are you doing? No, we didn't get to fly the contest, it rained buckets and buckets so everyone left on Saturday. I don't think the contest was rescheduled. . . .
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tommy s

My Feedback: (55)

If you're running a YS 1.40 or 1.60 DZ there is no tank pressure.

tommy s

bubbagates

My Feedback: (32)

On the YS140 Sport there is. I have one in my CG Sukhoi and if I screw up and do not release the pressure first I can shoot fuel a pretty good distance if I take the fill line dot off first

MikeEast

My Feedback: (3)

I think Tommy was talking about the DZ line. I know for sure the 1.60 doesnt have pressure and you need to run a loop in the fuel line to keep the fuel from running out the vent in a vertical dive. I Dont have a 1.60 but Earl Haury gave me a nice tutorial on the DZ engines and his setup at the Jetero contest a few weeks ago.

bubbagates

My Feedback: (32)

I apologize then, after re-reading his post it does seem as though he meant the DZ engines.

My bad, Sorry Tommy

Gregg G

My Feedback: (7)

If I I can save that much weight with the Dr Pepper bottle, just think how much I can save using a 2 litre!.....
Greg

Jim Oliver

My Feedback: (1)

Yeah---How about a DIET Dr. Pepper bottle!!

ofremmi

Dear sir's
Some years back i used a 1.5 litre PET bottle (coke) to measure up Nitro when mixing my own fuel. After a while (some months) the nitro contents in my fuel became less, the Nitro had done something to the bottle making it smaller. Yes, the bottle was both lower and thinner. This is most likely a minor issue with normal fuel, but over time your fuel-tank made of PET might become slightly smaller.
Regards

TOYMAKER

My Feedback: (6)

One other note on this Coke bottle fuel tank.

I noticed while out flying the other day that I forgot to reset my timer to allow for 3 oz less fuel. To my surprise I was able to fly the same 16 min on this 16.9 oz tank where as I was using a 20 oz Du-Bro before. The Coke bottle seems to contain the fuel closer to the pickup clunk better then the flat bottom Du-Bro tanks does. I was getting intermitent gulps of air when the Du-Bro tank would get down to the last several oz.

So not only did I
1. Saved $5.00 in parts
2. Saved 1.7 oz of weight

But I also solved a fuel draw issue that was occuring as the fuel was getting low.

Hurrah for pattern builders ingenuity.

Smooth Flying.....

Wayne Galligan