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View Full Version : Twin Fuel Tanks for Trex700 MW44 - Done


DDragon
02-07-2010, 05:22 PM
I was wondering if anyone knows where I can get some of that green heat resistant wire wrap that Wren uses for the gearbox lube pipe. I think my fuel lines from my twin fuel tanks may be within 2-3 inches of the exhaust and I want to make sure they are safe. Wish I could use steel or metal pipes from the tanks but I haven't figured out how to do that.

I'll take a picture and show everyone what I did. While it's currently untested is look pretty cool. I'm able to run two 1 liter fuel tanks on either side with a BVM tank in the middle using an old motor mount from my wren/pred.

DDragon
02-07-2010, 05:35 PM
As I mentioned, it's untested. I haven't secured anything permanently yet since I want to wait for the MW44 to come in and have it assembled and tested for balance and placement before I do that. But at least I worked out an easily reversible and secure way of attaching them.

cbergen
02-07-2010, 08:50 PM
A couple of observations.

Are 2 ONE liter tanks necessary? It's alot of weight to be carrying...

As you have the tnaks mounted right now, they are behind the mainshaft. This means that as you burn off the fuel, your CG will change...

DDragon
02-07-2010, 09:00 PM
Hi Chris,
good point. I have some smaller ones I can switch to. Maybe I'll give them a try. The tanks aren't in their final position. I'm still not sure what that will be. Depending on how things work out I'll have to adjust the tank size and the CG.

But thanks. I'll keep those things in mind.

Right now with my Wren/Pred as I burn off fuel it gets very noes heavy again... I'll try to avoid that with this model.

Cheers.

burton8012
02-07-2010, 09:41 PM
no offence man but that heli is gunna like dumb as hell unless you have like a scale body around those tanks no matter what size you end up using

DDragon
02-07-2010, 09:49 PM
no offence man but that heli is gunna like dumb as hell unless you have like a scale body around those tanks no matter what size you end up using

LOL... thanks. But it's basically the same design concept as Chris Bergens. And I always thought he had good design sense :-) In any case, it's still in it's prelim design stages.

Chris, I found my 450 ml bottles. I may switch to these.

Anyone know what kind of flight times they're getting with roughly 1 litre of fuel? (1000ml)

BTW... I just posted this and looked at the side view pic again ...LOL yeah. You're all right! These are BFT aren't they! Yeah, I'll switch to the smaller tanks. I also have a set of Budweiser steel bottles that I pickup up in Disney world (yeah, they held beer),,,, thought of using these as well!

cbergen
02-07-2010, 09:55 PM
I have 2 ea .5 Ltr tanks on my personal bird, and get between 9 and 12 minutes, depending...

Our 44 Magnum now comes with .6 Ltr tanks as the .5 ones have become scarce...

DDragon
02-07-2010, 10:00 PM
I have 2 ea .5 Ltr tanks on my personal bird, and get between 9 and 12 minutes, depending...

Our 44 Magnum now comes with .6 Ltr tanks as the .5 ones have become scarce...

LOL...ok... I admit it.
I GOT CARRIED AWAY :arggg:

Thanks Chris. I'll switch them up. I can't imagine needing more than 10 minutes. That's what I get on my wren/pred and it's more than enough.

DDragon
02-07-2010, 10:09 PM
OK... here are the smaller tanks. These are 450ml. They look more proportional, and I can work out the final position to maintain CG once I have everything installed.

I can adjust the bracket to bring them up higher and forward more if necessary. The aluminum caps originally came from these bottles so they'll screw right in.

lperagallo
02-08-2010, 12:08 PM
Deron,

These look a little low on the frame to me. I thought you wanted the weight as close to the head as possible. I would think it is harder to roll something with the weight hanging down. Now if you aren't going into 3D I would think this would make the bird more stable.

But, I'm not a engineer so it may not make any difference.:dontknow

Lou

DDragon
02-08-2010, 03:22 PM
Deron,

These look a little low on the frame to me. I thought you wanted the weight as close to the head as possible. I would think it is harder to roll something with the weight hanging down. Now if you aren't going into 3D I would think this would make the bird more stable.

But, I'm not a engineer so it may not make any difference.:dontknow

Lou

Hi Lou,
Yes, I thought of that. I don't plan on doing 3D at this time. So I'm not too worried about it. But I have a second set of plates that I can use to bring the tanks up as far as they will go (level with the main gear) that I can switch to in about 10 minutes. Once I get the engine, and get things together I can adjust and readjust... nothing is set in stone right now.

I like this part actually, figuring our solutions to engineering problems, testing, reconfiguring and retesting... :P So these will just be a starting point until I can get her in the air.

But yeah, I'm not a 3D guy. Hovering and basic forward flight it all I care to do at this time.

But I DO APPRECIATE the comments on my designs. Gives me food for thought, and I never would have noticed the humungness of the first tanks if it wasn't for Chris.

Talk about not seeing the forest because of the tree! :arggg::lol::oops:

burton8012
02-08-2010, 03:25 PM
how would that work isn't the exhaust going to be in the way?

DDragon
02-09-2010, 11:22 AM
how would that work isn't the exhaust going to be in the way?

No, I checked it before the install... the exhaust is forward and inwards about 2-3 inches. The picture is actually pretty bad I noticed. Since I was shooting down it makes it look like the tanks are level to the base of the frame.... but they are closer to level with the main gear.

On my other turbine heli (Wren/Pred) I'm running the fuel line right below the exhaust. I have some heat resistant wrap from wren on it and I've never had a problem. So they should be fine. The fuel lines from the tanks will be 2-3 times farther away than the other heli. Plus I'll have wrap on them. Forgot to mention that the inward side of the tanks stick out about 1/2 - 1 inch from the sides.

I'll give it a try... what's the worse that can happen? She blows up and catches fire! :shock:

burton8012
02-09-2010, 11:53 AM
align should of made the stock gas tank bigger they have room to have made it bigger stock one sucks since it sucks fuel up like a bitch in idle up

DDragon
02-09-2010, 12:01 PM
align should of made the stock gas tank bigger they have room to have made it bigger stock one sucks since it sucks fuel up like a bitch in idle up

Yes, I know what you mean. If this doesn't work I'll switch to a converted Align tank like everyone else. But I wanted to try this out first. I always admired the Bergen twin fuel tanks and thought I'd give it a try. Like I said, the design and problem solving is the fun part for me. I may end up selling these and starting a new project. I like the wren power plants and won't consider a nitro power plant now that I had a taste of turbine.

The electrics are fun, but the batteries get expensive.

burton8012
02-09-2010, 12:24 PM
theres a converted align tank mod? you have a link?

cbdane
02-09-2010, 12:26 PM
The electrics are fun, but the batteries get expensive.

As a pilot of 90-size nitro, electric, and now turbine helis, I've got to point out that the electric heli is the least expensive to operate, by far, even when factoring in the price of batteries. My 700E is 12s1p and I paid $75/ea for the 25C 6s packs ($150 per 12s, EMS shipping from Hong Kong included). My experience says that I'll get a good 100 flights (8 minute each) out of these. I only get 7 flights on my 700N for each $35 gallon of 30% fuel. And we won't talk about the equipment cost on the turbine... :P

burton8012
02-09-2010, 12:32 PM
yeah thats true...i just love thar sound and smell of a nitro


i might have to switch to cheaper fuel to get more flight time Magnum Pro-formance Fuels (http://www.magnumfuels.com/index.php)

$18 for 30%DS bucks a gallon or $23 bucks a gallon for the little bit better 30%

DDragon
02-09-2010, 03:12 PM
As a pilot of 90-size nitro, electric, and now turbine helis, I've got to point out that the electric heli is the least expensive to operate, by far, even when factoring in the price of batteries. My 700E is 12s1p and I paid $75/ea for the 25C 6s packs ($150 per 12s, EMS shipping from Hong Kong included). My experience says that I'll get a good 100 flights (8 minute each) out of these. I only get 7 flights on my 700N for each $35 gallon of 30% fuel. And we won't talk about the equipment cost on the turbine... :P


True, I wasn't thinking of the initial build costs. Just the running costs.