Fuel Tank Mod on Bergen

[dperry]

I got very tired of never knowing how much fuel I have so I replaced the fuel tanks with clear nagaline bottles. They were $7.00 ea and I used the fittings off of the old metal ones. This took all of 30 min to do. I used some hysol on the fittings so they won’t leak. If you did not like the clear look you could paint them and leave the back un-painted or a vertical ½ wide strip unpainted. The fuel capacity is 32oz per bottle, and they don’t even get hot. I was very concerned about the heat but it appears to be a non issue I let it sit at idle until both tanks were empty and the tanks were warm but not hot.

[cbergen]

Very Nice, Don. Excellent find.

[Greg Alderman]

Cool Don...I looked at those a couple of months ago when I was bored on a Mission and was walking through a REI store...almost pick up a set but decided I really didn't wan't that much fuel! but I do like the idea of seeing the fuel level...guess you don't have to fill them to the top if you didn't want to! :D

[dperry]

Cool Don...I looked at those a couple of months ago when I was bored on a Mission and was walking through a REI store...almost pick up a set but decided I really didn't wan't that much fuel! but I do like the idea of seeing the fuel level...guess you don't have to fill them to the top if you didn't want to! :D

This heli hasso much power who gives a sheit. Plus you get a little more flying time, in stunt one mode!

[WillJames]

Not being able to see the fuel is kinda weird for me as well Don. I like the clear bottles, they look really neat and clean on the machine.

[Heli_jack]

I switched my scaler over from a hidden, non visible, to visible tanks. I never burn too much, but I sure like to see what I had left when I get done flying. Just cheap a$$ed Sullivan stuff.

So where did you get these? Nagaline? Size choices?

[dperry]

I switched my scaler over from a hidden, non visible, to visible tanks. I never burn too much, but I sure like to see what I had left when I get done flying. Just cheap a$$ed Sullivan stuff.

So where did you get these? Nagaline? Size choices?

I bought these at a camping store. $7.00 ea

[dperry]

After flying with the 32oz per side fuel tank I was getting a vibration that would not go away at any head speed, you could see it in the fuel tanks and skids. With that much extra weight, the frames moved way more than I liked (if you were to grab the front of both fuel tanks and move in and out towards each other you would see what I mean). This is a place where the frames are not stacked. So I put an aluminum tube and threaded both ends to use as a stiffener. This eliminated the independent movement of each tank but now they can move together back and forth in unison, but only about ½ as much as before.

Ok, I’ll try smaller tanks with less weight. The only other size that I can find in clear or smoke is 16oz per side. I don’t want to go any smaller than 20oz per side if possible. So I had to compromise and use 18oz per side tanks in the off white. While not clear you can clearly tell the amount of fuel that you have onboard.

The tanks I’m using now were bought at Academy camping/sports store, and cost $3.99ea

Nothing like being a test pilot!

[heliman53]

Don, I saw the same problem with flex when I was fighting a resonence issue with my Intrepid Turbine and I made an aluminum ross brace just in front of the clutch and added a G10 brace to each side aft of the main shaft to tie the upper and lower frames together. This helped a lot, I think I still have a set of the braces left if you pm me your address I will send them to you. Craig B

[wolfdad]

Don,
Absolutely fantastic!!! I went to the 32 ounce fuel bottles for about the same reasons you did, however I just wasn't sure about some of the same things that you expressed concern over. I think, after my visit at HeliFreak, I will venture on over to REI. BTW, Don, and I am sure you already know this, Chris has the mounts for the larger tanks as well.

Your comment about "power to spare" is absolutely the truth. With no fuel on board, dry weight is just over 22 lbs, so you can figure another 4-5 pounds with a full bag of fuel on board. The Bergen/Wren combination is so gol-durned adaptable that I think you could do just about anything (within reason).

Hey Alderman, you kicking back and enjoying yourself :wink: You have to admit that there is "life after retirement."
Doc

[heliman53]

Hey Doc, I would retire tomorrow if I had the means! Craig B

[wolfdad]

Craig,
Unfortunately, my retirement, at this point, was not all my decision. I had planned on working another couple of years, then going out the door. However, circumstances, as they always do, dictated the course of action, so we went with the flow, adapted and, I think we are going to overcome. I can tell you one thing with absolute certainty and, that is I have a lot less respect for "big brother." This will always be MY country, however I wouldn't lay claim to most of the folks this country employs....and, unfortunately, I was one, both Navy and civil service, the civil service being the part that I most sorely regret.

Sorry to digress off the subject...did not intend ot hi-jack a post...just saw Gregs reply.
Doc

[Sparkhead]

Hi Don,

Does the heat from the exhaust have any effect on the bottles?

Mick.

[heliman53]

Mick, I tried some plastic rectangular tanks on my Bergen for a bit. They were nearer the exhaust at the front and lower as well, after testing I found that the exhaust plume passed with no problem . The flow travels much more outward than rearward, even after flying fast forward there was no warming of the tanks at all. Craig B

[Sparkhead]

Hi Craig,

Thats good to hear, I remember the heat that came out of the exhaust even at idle and was a little concerned.

[heliman53]

Mick, your right you only get too close once like to set tracking really warms your knees! Craig

[wingtip]

http://www.usplastic.com/catalog/category.asp?catalog%5Fname=USPlastic&category%5Fname=15032&Page=1 Nalgene bottles of all sorts and sizes



http://www.karstsports.com/nalprod.html Nalgene bottles of all sorts and sizes




http://www.smallparts.com/products/storagesolutions/scienceware/ poly P, E type bottles of different sizes.

[wolfdad]

Also REI sports has a wide selection of both aluminum and composite bottles that work extremely well....also a good source for the Powermax fuel if you order in quantity.

I have used both the composite and aluminum bottles on both my Hobbyparts conversion and Bergen turbine with absolutely no problems with heat. In fact, on the Hobbyparts conversion, I temp-taped the bottles out of concern for potential heat degradation and found absolutely no discoloration. Extended use may cause discoloration of any paint coatings directly above the exhausts, however I think this is more from exhaust residue than heat. Greg Alderman has a helluva' lot more hours on the Bergen than I do and I think he can confirm these findings.

The absolutely wonderful thing about the Wren turbine is that, with the second stage design, most of the heat and energy that would normally be expected with a thrust-type turbine is expended in driving the second stage...one of the HUGE advantages in using a Wren.

Happy New Year to Everyone!!!! :D
Doc

[cbergen]

The absolutely wonderful thing about the Wren turbine is that, with the second stage design, most of the heat and energy that would normally be expected with a thrust-type turbine is expended in driving the second stage...one of the HUGE advantages in using a Wren.

Can I quote you on that Doc? One individual expressed disdain with the placement of the exhaust in this configuration, with worry about the main gear and servos, especially in a hover :roll: , and your explanation is better than anything I could express.........

[wolfdad]

Chris,
Hope you received my PM...many thanks to you, shipmate and, our best wishes for a wonderful New Year to you, your Dad, the boys, Mary Ann and all the rest at Bergen.

Chris, you may quote me without reservation or qualification. Quite honestly, when I got the Hobbyparts conversion completed, I was extremely concerned about the placement of the exhaust and the plastic fuel bottles, so I "procured" some temp tapes that had a range of 90° F to 150° F and saw NO discoloration and I believe you know how close the exhaust was, having seen the conversion at Birmingham two years ago.

My large (32 ounce) aluminum tanks are painted white (see video) and because of the size, are much more "over" the exhausts than the 20 ounce tanks were. The only thing I have seen is some very minor discoloration of the paint due, I think, to contaminants in the exhaust vice heat. I just went to cable ties for mounting and prior to that was using Velco for mounting with no discernible degradation.

And, the skids would, in my opinion, be a total "NON-Issue" under any stretch of the imagination.

And, BTW, almost all of my flight time on the 4 blade Bergen has been hovering with some limited forward flight and manuevers, due to the tail issue you and I have discussed....which will change shortly after the new year.

Also, for those of you interested, I have shielded my elevator/pitch servo with both header heat insulation and a layer of the Wren heat shielding (as recommended by both Greg Alderman and myself from past experience). I also run a Venom temp probe directly beneath that servo and have seen temps of up to about 130° F (depending on ambient outside temps) which have NOT produced any degradation in servo performance. I do strongly recommend that servo be insulated from the hot section and the Wren heat shield has worked extremely well both on the Bergen and on my BK-117.

Yes (and, don't get me wrong on this issue), the Wren exhaust temps are definitely capable of doing damage (don't want anyone going out and touching the exhaust during or immediately after operation) to items in close proximity, however, compared with a thrust-generating turbine, the difference in temps, because of the energy dissipation of the second stage are phenominally lower, allowing some options to be used that normally wouldn't be available. :D :D :D

I also think that Don's idea is absolutely fantastic. Because of the mounting location for the Helitronix mixer for the four blade conversion, I have a great deal of difficulty seeing the UAT and, by the time the fuel is down to that level, one is "pushing the evelope" on fuel anyway. And, once the UAT gets its "turbine staining," it's a ***** to see the fuel level anyway, so Don's idea is great! Also, if you plan on using "clear" fuel bottles, Lexan seems to be quite impervious to kero and Jet A1 and, for some reason, retains its clarity without the normal "staining" you see in the Tygon and other turbine-related materials....just my 2 centavo's worth on the subject.
Doc

[heliman53]

Doc, I also used a layer of heat blanket below the servo and againjust below the upper frame to lower frame junction. The only time my elevator servo saw much heat was after shutdon when everything tends to heat soak. Even then it was not enough to cause a problem. Craig B

[wolfdad]

Craig,
Roger your last.
Doc