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Removable Wing Fuel Tanks?


mlefebvre

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I was wondering if the engineers here could maybe help me with some ideas about removable wing fuel tanks.

 

I have seen one of the Long-EZ's that went on the long distance flight had torpedo like fuel tanks under each wing. Dick Rutan was saying that they were a "permement" modification (we all know nothing is permement in fiberglass) that were made for the trip.

 

I was wondering how hard would it be to design a latching system that could support these tanks when needed and then be removable when not needed. Kinda like what bombers use to hold their payload under their wings. He was very helpful in the design of the tanks themselves and how to attatch in a permement fashion, but I was interested in taking it step farther. Any ideas out there?

 

Marc

Tis far easier to ask for forgiveness than for permission.

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That is an interesting idea. I hadnt considered air force surplus for such a thing but that would make sense. Does anyone have any links to websites that carry air force surplus parts? Or any ideas to a source for attatchment points for fuel tanks used on other craft.

 

The main reason I was thinkin of "re-engineering" is that our application has to be LIGHT to be RIGHT. As such, most of those military applications would be for 500lbs fuel tanks and over built to the max. BUT, I guess the attatchment mechanism could be duplicated on a smaller scale. Hmmm.... Wheels spinning....

 

Marc :D

Tis far easier to ask for forgiveness than for permission.

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Marc I am new to aviation and to building my own plans built airplane............but I keep hearing Dust and Nike saying.......Just do it

 

I figured you were probably looking for real ideas, and perhaps even some kind of sketch.

 

I just really admire people who let nothing stand in their way, and I know there are quite a few of them in here.

 

I wouldn't be surprised if you find someone with plans aready drawn up--- BUT if not.....Just do it.

Joseph@TheNativeSpirit.Net

I am Building a Jo-Z IV StarShip.

 

What Do YOU Want?

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Surely it would be quite a simple operation to make a bracket to which the fuel pods could be bolted, and when removed a blank plate bolted in place. You weren't planning on having drop tanks surely?

Then use a simple fitting with a tap and connector to link the fuel system when the tanks are connected.

:D

The Coconut King

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A simple bracket would work. I was thinking of something a little more sophisticated where the connection was more of a "hook" arrangement which helped hold the tank in place with air pressure rather than loading the bolts.

 

I believe that the epoxy guru, Gary something, manufactures a baggage pod which looks a lot like a spare tank, but isnt. Maybe it could be adapted. Another thought for a form - how about using a large set of wheel pants as the basis for forming a tank?

I can be reached on the "other" forum http://canardaviationforum.dmt.net

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To Marc (mlefebvre):

 

Since you're located in Hawaii, I'm guessing you're wanting more fuel capacity to extend range. There are a number of ways to expand the Cozy's fuel capacity without going to externally-mounted tanks.

 

The first and most simplest way is to trade strake baggage area for fuel. Just don't cut out the fuselage sidewalls and use all of it (inboard of R33) for fuel! If you do desire some strake storage area, you could glass in another bulkhead halfway (or a position of your choosing) between the fuselage and the R-33 rib. You'd need to cut some semi-circles into the R33 rib and move the drain petcocks to the lowest location. I haven't stopped to calculate it, but this would add a substantial amount of gallons.

 

The second thing would be to convert the "transition filler pieces" into fuel bays. These are the areas between the outboard diagonal strake ribs and the wing roots. You end up carving a piece of urethane foam to close out these areas. It's trivial to use these areas for fuel, probably good for a few more gallons.

 

The third thing I would do is create a removable fuel tank that could be affixed into the rear passenger compartment. If you desire storage space for the longggggg trip, build a tank that takes up the aft compartment and stops at the height of the rear armrests. Or, if even more fuel is desired, build one that goes up to the top longerons. There would still be some room above it to pack stuff.

 

All this being said, I have not stopped to evaluate the effects on max gross weight or on weight and balance.

 

Oh, and one more mod you'd need......don't forget about relief tubes!!!

 

 

Wayne Hicks

Wayne Hicks

Cozy IV Plans #678

http://www.ez.org/pages/waynehicks

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I think he wants to hop FROM Hawaii !

300 knots at FL 250, it's only 7 hours.

I see the attachment of the tanks on the EZ that went from Switzerland to Cape Town kind of hook over the leading edge, makes sense looking at it.

Belly cargo pods are popular on planes like the Caravan, and I've seen wingtip tanks and baggage pods. Supposed to be good for the induced drag aswell.

:D

The Coconut King

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OK. Let's examine this deal for a moment. Think it through ....

 

Military drop tanks start at 300 gal (that's 2000# of JP5) for smaller fighters, up to 450 and 600 gal for thuds and 3000 (that's thousand gal for BUFFs. The tank might weigh maybe 10% of its capacity. Not a good source for our purposes IMO.

 

That said, your tanks are already available - just get a couple of baggage pods and seal them up. They come on and off with a few screws (which you'd probably have to beef up a little) and look like about 10-15 gal. Readily available and easy to adapt.

 

About transfer: The military transfers with compressed air (readily available, no moving parts or mechanisms inside the tanks or pilons). I think that would be our best way too. I would envision perhaps a 3/8" Al tubing permanently plumbed through the airframe (ending in a cavity under the wing, over the pilon with an access door). The air line and fuel line would be plugged when not in use. Only the few oz of plumbing would be permanent. Air and fuel lines would be connected as the tank was mounted. All you need is a reliable seal on the tank filler. An electric air pump (3 psi or so would suffice I should think), installed, plumbed and wired when tanks are installed would flesh out the system.

 

For procedures, one might have a little inspection window in the pilon through which you could see the fuel transfer when you turned on the air pump on momentarily during pre-flight. Enroute, while you still have sufficient fuel to return to your departure point (just like the military does) turn on the transfer and watch the fuel in the strake increase. When transfer is complete, turn off the transfer pump and continue the march.

 

Now you've got it, what are you going to do with it. It has already been made clear that the airplane will already outlast all but the most outrageously distended bladders, so the tanks would be very little utility in the contiguous states except perhaps for Greg Richter. Relief tubes have been mentioned. Don't know how many of you have ever used one, but you have to be hung like a bull:( to avail yourself of the facility without making a terrible mess. Pampers come to mind.:rolleyes: Which pretty much leaves us with substantial trips over blue water. We could visit Hawaii (if the engine could be relied upon to make the trip):( and our Hawaiian brethren could fly to OSH.

 

It would appear therefore, that we have two candidates for further development: Greg Richter and (whatshisname) in Hawaii. And, of course, all the folks who are turbocharging Mazdas.:) The former are a pretty thin market; the latter more numerous if less motivated.

 

Did I leave anything [important] out? .... Jim S.

...Destiny's Plaything...

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Yes, this is so I can get to the mainland on occasion from Hawaii if need be.

 

Excellent suggestions. I think my first plan of attack is to recover as much space in the strakes as physically possible. I have considered the rear seat bladder as well but was curious about another solution with external pods as described. Does anyone have any links to the baggage pods I keep hearing about? I would love to see what they look like, how they attatch, etc...

 

I didnt want to make too many permament changes since 90% of my flying is going to be around the islands. You guys have been VERY helpful.

 

I am ready to start my build my only sticking point right now is place to build. I have been working mostly on solving that final problem. If you recall I am living in a townhouse. The airport doesnt have any hanger space available unfortunately. I have looked into renting industrial warehouse space in the industrial park and have found it pricey ($1/sq ft). I am having a house built but it wont be completed for a year. So, until I resolve the WHERE to build issue I am in a holding pattern.

 

I figured I would spend this time getting primed and ready and obtain as much knowledge as possible. I have worked with EPOXY for years in the windsurfing business so, layups are second nature, otherwise I would practice. My next idea is to approach some friends I know who make custom windsurfing boards out here and see if I can rent a corner of his manufactuering loft in Haiku. Anyways... Im off topic as usual. :)

 

Marc :D

Tis far easier to ask for forgiveness than for permission.

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...my first plan of attack is to recover as much space in the strakes as physically possible....>

<... didnt want to make too many permament changes since 90% of my flying is going to be around the islands ...>

Isn't that a bit of a contradiction? I the basic airplane provides you plenty of fuel for the islands. Don't give away something you're going to want back. Rear seat bladder or external tanks should give you plenty of fuel to make the mainland. You'll want something besides fuel tanks, a toothbrush and a change of skivvies when you get there.:)

...Destiny's Plaything...

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Your correct in pointing that out. I guess I should have been more clear. I would rather make internal changes to gain more fuel space than permanent external changes (ie. adding pods, or other permanent "add-ons"). I worry about the affects of balance and drag and other factors that external changes can make. I think enlarging the fuel tanks in the strakes (as long as they don't change the size of shape of the strakes) would have the least amount of net affects of the change. I could be wrong but I think the fuel tanks sit on the COG or close to it. Adding the rear seat bladder is another option that would make the least amount of changes as again, the weight of the fuel would be like having a backseat passenger (or two).

 

Adding external fuel pods would probably be the biggest engineering challenge but an interesting one to consider. it would require permanent mounting points and reinforcements in that area which could have other structural impacts. Definitely more complex, but, still doable.

 

I hope I am clearer on my train of thought. :)

 

Marc :D

Tis far easier to ask for forgiveness than for permission.

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The reason I like the wing tanks is that they are removable (takes about 10 min). The back seat bladder is also easily removable. That's why I favor it. It installs/removes quickly. Converting the baggage part of the strakes to more fuel will affect CG. Most of the baggage area is forward of the CG and it is biased pretty far forward. The strakes are the only permanent change under discussion.

...Destiny's Plaything...

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Hmmm... interesting points... I suppose once i get more intimate with the details of the build I will be better suited to suggest these kind of changes. Thats why this forum is so useful, cause you guys for the most part have "been there, done that".

 

Again, any www links out there for those baggage pods I can look at?

 

Marc

Tis far easier to ask for forgiveness than for permission.

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Originally posted by mlefebvre

Again, any www links out there for those baggage pods I can look at?

 

See:

 

http://web.tampabay.rr.com/chipmar/pods.htm

 

http://web.tampabay.rr.com/chipmar/eze-thumbs.htm

 

http://www.prekas.nl/longez.htm

 

http://www.noaa.inel.gov/capabilities/LongEZ/

 

 

These were found with a 2 minute search on Google for EZ baggage pods.

 

figure on a 5 - 7 kt speed loss.

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OK, for nonbuilders, after building most of the plane I now feel like i can build about anything out of foam and fiberglass, it only takes time and if i have to design it and figure out how to build it ALLOT ALLOT of time, but time is it

 

you throughly understand "hard points" during the construction u use aluminum, 25 layer glass, wood, extra dense foam, etc, etc to harden attach points, you make all kinds of parts and you can tell how strong they are by trying to break the pieces you later cut off.

 

one small piece frustrates my kids, in thier 20's and 30's, they have been jumping on it for years trying to break it. The building is like a structural engineering course without studying, don't worry, it just happens.

 

OK so maybe some testing too, he he he

 

enjoy the build

 

mike

maker wood dust and shavings - foam and fiberglass dust and one day a cozy will pop out, enjoying the build

 

i can be reached at

 

http://www.canardcommunity.com/

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Marc, those are exactly what I am thinking about. Those would make darn sexy fuel tanks. ;) I wonder though how useful they are as intended and baggage pods? They dont seem large enough for that.

 

So, here is a question.

 

Using such tanks, I wonder what the best method would be to integrate them into the fuel system? Should they suppliment the strake fuel tanks as someone mentioned, or should they feed direct as two seperate sources of fuel (for a total of 4 includeing the strake tanks). Would each pod contain its own sump? Curious about possible solutions and opinions?

 

Marc

Tis far easier to ask for forgiveness than for permission.

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Baggage pods are always useful in a plane - any plane!

 

While I expect I'll normally have plenty of space (my normal mode will be 2 plus baggage and dogs) having someplace to stow the chairs would be great - the chairs we have collapse to about 3-1/2 ft long by about 6" tubular each.

 

So - am I better building one larger pod, or two matching "missile launchers" - or two slightly mismatched so one could be stowed within the other for easier transport?

/dan

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you know, after thinking about it, i think i would rather have the over the wing tanks that the other long that flew around the world had.

 

gravity plumbing, less stress on a single point.

 

enjoy the build

 

mike

maker wood dust and shavings - foam and fiberglass dust and one day a cozy will pop out, enjoying the build

 

i can be reached at

 

http://www.canardcommunity.com/

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  • 4 weeks later...
  • 1 month later...

Why not build conformal fuel tanks directly beneath the strakes and against the fusilage? That way you could plumb them to connect to the strake tanks? The military likes conformal tanks (better performance in high-g manuevers, lower drag).

 

I don't really know how you'd go about it. Alternatively they could be above the strakes, like in the new F-16 Block 60's we are selling to UAE.

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  • 11 months later...

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