New Tank Configuration for Wren 44

[DDragon]

Well, as mentioned in another thread. Here are the pictures of the new tank configuration I have for my Trex744.

As some of you may remember, I originally had those twin (ugly) green tanks on the sides. I decided to streamline it and place a smaller 24 oz. Du-Bro tank below the tail.

The twin tanks were 30 oz with the BVM, this one is 24oz. I was getting 15minutes with the twin tanks... took here for a spin today and I'm getting 8 minutes leaving about 1 oz of fuel in my BVM. It's a little less than I expected. But not bad.

The CG is actually more to the front (even with a full tank) now which I think is strange... but it's not bad. I may be able to even it out more.

Thinking of placing a couple of small overflow tanks on the side to add more time. But not sure how to Plumb it as this stage.

If people can respond with their current fuel capacity and flight time using a wren 44 I'd appreciate it.

Forgot to mention. I have it titled slightly back so that all the fuel drains. Once I get my CNC mill up and running I plan on making a better set of mounts out of CF.

Thanks.

[cbdane]

Oh my, not sure. Looks a little cobbled on, IMHO. Please accept this with the helpful spirit that it is intended.

[Aussieheliguy]

Is that a good idea to lay the gas cylinder on it's side? I would think liquid gas would be more likely to flow out of the cylinder like that.

[ppridday]

Gotta agree with cbdane to tell the truth. That is where the tank sits on my Pred/Wren and I hate how mine looks. I'd rather have the saddle tanks on mine... Sorry dude... We could all have a if that helps...

Paul

[DDragon]

Thanks Paul thanks cbdane

Actually I adjusted it today so it sits higher. Right now this whole exercise is just for proof of concept. If the positioning works out I'll make some better brackets out of cf once I get my cnc mill up and running.

So far it's not bad, but I'm unsure about the center of gravity and I'm only getting 6-8 minutes flight time. I was getting 15 out of the twin tanks.

If this doesn't work out maybe I'll go back to the side tanks. Actually, I saved a set of Budweiser can/bottles I thought those would skew cool fuel tanks.

But this is just another winter project

Hey Paul, forgot to mention, it handles like the wren pred with this configuration... Not sure if I like that. I can see myself going back to the side tanks once I get my machine working... One thing for sure, the side tanks with the PVC brackets may have looked like hell, but it was really well balanced.

Thanks guys, I do appreciate your comments thats why we pst here right?

[DDragon]

Originally Posted by Aussieheliguy

Is that a good idea to lay the gas cylinder on it's side? I would think liquid gas would be more likely to flow out of the cylinder like that.

Forgot to mention.... I have it like this on my wrenpred too... Never had a problem.... But I don't fill it up much...just a squirt to get it started. I think if I filled I up more it would cause more problems.

[DDragon]

Just for fun... here's a pic of the tank a little higher... I lifted it about 1 inch. It's very stable and sits well between the rails. But the CG is off and the time still bugs me.

[lperagallo]

With the Bergen setup of side tanks at .6 liters a piece I fly for 9:30 with a 2:00 reserve.

Tanks sit centered over the main shaft so there isn't a change of CG as it flies.

Lou

[MattJenner]

Yeah deffinatly would not put gas cannister on its side, it needs to be upright or neat liquid will enter which will expand in the turbine and cook it to near melting point.
On my Longranger where by design the cannister is on its side under the rear seat i allowed this to happen and On a data download i did, my MW54 i had reached 1100oC, thinking the ECU would shut it down i carried on with the startup process.
It was only after a chat to Wren that i found out, that on the startup some of the fadecs dont shut down a high temp,and some do, but they did not know which ones did and which ones didn't, I have a Mark 4, 54.

I stripped the turbine down, and could clearly see where it had really over heated, so after this as turbine was down on power, I ensure that my cannister is vertical on all my turbine machines.

Matt

[DDragon]

Hmmm, been thinking. I may pull everything apart and go with the stock tank and position. CG can really make or break the fun factor. And it's not too fun.

[DDragon]

Do most people get two stock tanks, cut them in half and plastic weld them together to make them larger? I may give the a try.

[rcnz]

How long is the flight time with those using the HeliChris conversion with that big round tank. You might be able to get the big round tank and cut to fit into the standard 700. Looks tidy, Just a thought.

[Laurens]

I really felt a difference in the whole flight, because of CG issues on my Predator Jetcat with the tanks in the back.

[kevinww]

Originally Posted by DDragon

Do most people get two stock tanks, cut them in half and plastic weld them together to make them larger? I may give the a try.

Tried that and it worked, apart from if you left it standing with any fuel left in the tank. It would slowly leach out through the joint if it wasn't perfect. Eventually settled on 2 700 tanks side by side in the normal 700 position and hooked up in parallel.

[DDragon]

Originally Posted by kevinww

Tried that and it worked, apart from if you left it standing with any fuel left in the tank. It would slowly leach out through the joint if it wasn't perfect. Eventually settled on 2 700 tanks side by side in the normal 700 position and hooked up in parallel.

I thought of the as well, reminded me of my Harley tanks. How did you get around the problem of the right side of the tank not being square? Do you have any pics?

Thanks

[kevinww]

Its not really a problem, you just angle both tanks towards the back slightly.

[DDragon]

Originally Posted by kevinww

Its not really a problem, you just angle both tanks towards the back slightly.

LOL... didn't think of that?!

Thanks