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HomeTurbineAircraftHelicopterTurbine Helicopters › kevlar or composite tanks
10-26-2011 03:07 AM  6 years agoPost 1
1hander

rrApprentice

San Antonio, TX

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ive decide to try to make my own tanks, cuz i like learning new skills, i was planning on using some left over kevlar i have, its 5 ounce, i figure i will form from foam, maybe cover the styro with white elmers glue then wax the crap out of it then cover in kevlar and epoxy resin. let cure, cut in half, remove core, and reglass..if im doing it wrong please say so.

my questions are
1. is epoxy resin the right stuff
2. i see tanks have a metal ring, is this neccesary, if so do i just cut a hole and add and epoxy in the aluminum ring or just cut a whole in it afterwards and use it with a gas or smoke fluid stopper.
3. im planning on two , what capacity each should i go with on hp5 turbine at 1300 head speed, to get 10 minutes flightime ..
4. 1 layer or two

Ret. Dis. SSG Gonzales..5th SFG..De Oppresso Liber..Tantum Deus Can Sentio Mihi

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10-26-2011 10:25 AM  6 years agoPost 2
airplanejunkie

rrApprentice

Riverview, Mi.

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Have Fun
1. Shape your foam core. Styrene type.
2. Add by gluing an aluminum neck and cap asm to the foam core. Cut it from a bottle.
3. Apply Part-all release agent to the foam core. Do not apply to the neck area of the cap. You want the laminate to stick or adhere to the sanded base of the neck.
4. Remove the cap, glue with epoxy a 3/8 wooden dowel rod inserted far enough into the foam for strength. This will serve as a handle or location to clamp in a vise. Protect the cap threads with masking tape.
5. Mix exactly a sufficient amount of minimum 3 hour cure epoxy for one coat. Mix really well. Pour it into another cup and mix again!
6. Brush a liberal layer of epoxy onto the foam core. Saturate strips of your cloth on a glass plate with epoxy. Lay and position the strips all over the foam core. Please overlap the strips a minimum of 10%. Let it cure if your strips are not laying very well. Sand and apply another layer. I would do a minimum of three layers at 5oz. If your laminate is relatively smooth, keep going wet on wet is always best. Tap and push the saturated strips into the base coat with a brush dipped lightly in alcohol. This will prevent the brush from sticking. Let the epoxy cure per the directions. Sand, bondo and finish smooth.
7. Remove the stick. Slowly pour acetone into the opening. This will dissolve the foam. Repeat until it is all removed. Now wash out with warm soapy water to remove the part all. Sand and finish with a fuel proof paint system.
8. Call me if needed. I am never good at writing a book especially at 4:30 am. Thanks, have fun. Dave

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10-26-2011 02:08 PM  6 years agoPost 3
1hander

rrApprentice

San Antonio, TX

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thats pretty much what i was thinking, my tanks are going to be just square, i might make them conformal but i have a big enough cabin that they can just be square, i dont want to make it too hard for the kevlar to conform, to any weird shaping, also, i might cut them in half to remove the cores, im told that the acetone will still leave a gooey layer in there, id hate for any of that stuff to get into the filters and cause a flamout..

im going to use the same epoxy as you mentioned to put in the fitting, or some other typ[e of two part hysol like epoxy, i dont want to buy the hysol and the damn mixer and the plunger etc etc etc.

i might make it curved on the fuselage part of the wall,but i want the tanks to sit below the window a bit lower in the fuselage. for just a bit more capacity/learning , but dont want it too heavy

im going for 35-36 ounces each, which shoul;d be just about 12 total minutes runtime maybe just a bit more. if my research is correct the hp5 should be drinking about 6 ounces per minute at full power.

i can machine my own aluminum neck fittings, all said and done, i should be able to do both tanks in the 100.00 or just under range if i dont screw it up.

i found some tanks that hold 34 each, for 108 a piece, but since im in this for the education im stickin with it,

itll get more interesting when i buy a tig welder instead of buying the 700.00 exhaust, and make my own..that thin stainless sheet is a pain to weld

Ret. Dis. SSG Gonzales..5th SFG..De Oppresso Liber..Tantum Deus Can Sentio Mihi

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10-27-2011 12:10 AM  6 years agoPost 4
airplanejunkie

rrApprentice

Riverview, Mi.

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Fuel consumption
I believe you are way light on fuel consumption. My Ram 500 burns 9 oz per minute. Check with your engine for the real numbers. Dave

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10-27-2011 12:18 AM  6 years agoPost 5
1hander

rrApprentice

San Antonio, TX

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i was thinking the same so i called scott over at jetcat, and the manual stated 6.7 to 7.9 oz per minute so im thinking 8 to 8.5 is about right at full power plus the weight..i will adjust accordingly thank you sir

i read another post, i think it may have been heli suisse pardon if my recollection is wrong, that he was carrying two of the vario blue 1 (33.8oz) liter cans and was getting 6 minute flights including startup and burning only half his fuel baaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
i just saw the blue cans are 1.25 (42oz) liters that explains my error in volume calculation

Ret. Dis. SSG Gonzales..5th SFG..De Oppresso Liber..Tantum Deus Can Sentio Mihi

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10-27-2011 02:49 AM  6 years agoPost 6
1hander

rrApprentice

San Antonio, TX

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if the above men tioned members turbine is indeed flying 6 minutes on half of fuel supply the math says 7 to 7.5 ounces per minute which is right on par with jetcats quoted 6.7 to 7.9so 42 oz per tank is what ill go for

Ret. Dis. SSG Gonzales..5th SFG..De Oppresso Liber..Tantum Deus Can Sentio Mihi

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10-27-2011 09:24 AM  6 years agoPost 7
PETER ROB

rrElite Veteran

Devon UK

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6 min/litre
The first JetCat PHT3's top end rpm was goverened at 84000, these turbines useing one of the three available gearing ratio,s, indeed ran for 6 min per litre
As time moved on the PHT3's top end rpm is now 98000, so min/litre have now changed
You can shuffle the numbers as much as you like
The reality is how long does the completed helicopter fly with the on board fuel available

I have just done exactly this test on the PHT3/Cobra, I replumbed the system, with the 2.2L main tank and Vario (petrol) header tank
Fueled the system until the fuel ran out of the air bleed
Gas started the turbine, as soon as the turbine went over to Jet A1, started the timer
Put the Cobra up into the hover,(out of ground effect) and hovered until air bubble was visible in the top of the header tank
This was exactly 10 min
So my flight times are now timed at 9 mins, this will give me a safe margine
Had I used the math,s calculation, header tank 2.2L plus the header tank 2.5L approx, I would have crash landed

When building your own Kevlar fuel tanks, (mine are being used all over the world), the idea is to make a tank of max volume, to fit into your scale project around the CofG
Then carry out the above test, and you will know exactly how long you can fly
Peter R

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10-27-2011 01:23 PM  6 years agoPost 8
1hander

rrApprentice

San Antonio, TX

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Will do ... Thanks for the reply.

Ret. Dis. SSG Gonzales..5th SFG..De Oppresso Liber..Tantum Deus Can Sentio Mihi

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