Long Rang Fuel Tanks.

I know this is a sticky subject with Van's, but I would like to get the opinions of this group. I am sorry if this is a repost. I would like to get some more rang out of the RV-8 I am building. I have thought of several options and am at a stopping point.

Option 1. Learn to fly more effeciently, less power more range.

Option 2. Longer leading edge fuel tanks, Ok to do while building though I would run into problems with the pre-punched spars.

Option 3. Tip tanks, though I really want that space for antennas.

Option 4. Removable drop tanks, would look like a mustang and probably have some aerodynamic problems.

I am sure that everyone has thought of these and hope that some have already done some of these. Thoughts anyone, Brian Kelly

Don't reinvent ther wheel

Check out the Hotel Whiskey tanks. Inexpensive, easy to install and many units in service. http://www.safeair1.com/index.htm

Option 1: Always a very good idea to practice in any case.

Option 2: That has been done, but those who have ventured into that area have said that the amount of work involved in sealing another bay in the wing for fuel is, in the end, really not worth it. The gains you would have don't really make it worth attempting.

Option 3: One of the most popular long range fuel tank modification for the RV-8. I've read articles where people claim an additional 9-10 gallons, and there are already kits out there ready to install.

Option 4: That would look really cool, but you would have to (my guess) make some fairly major modifications to the wing skins and spar to hold the extra load. And again, unless you are planning to make large tanks (which will require even more reinforcement), you probably won't be able to carry that much additional fuel.

Other Option 1: Electronic Ignition...start making your airplane more efficient. Also, think about going to higher altitudes (oxygen?) to burn less.

Other Option 2: Extra fuel tank in either back seat or in baggage area. I know it's been done, but don't really know that much about it. Hopefully some more people will chime in here.

Also, for your reading pleasure, go to Dan's site www.rvproject.com and look at some of his latest entries...one of them was about fuel efficiency when running low power settings.

Good luck

flyboykelly said:

Option 2. Longer leading edge fuel tanks, Ok to do while building though I would run into problems with the pre-punched spars.
Brian Kelly

Click to expand...

Brian I did option 2 and added 2 bays to each side giving me 60gal total.
I:
1. Ordered one extra tank skin and split it to each side & Used a butt joint with a doubler to attach the added skin.
2. Ordered one rear baffle and split it to each side
3. Ordered the appropriate ribs
4. Ordered the extra z-brackets

Build and installation was easy and I have no regrets. Maybe could use a few more gallons and a couple more knots

Best,

ER tanks for Hotel Whiskey

I don't like the tip tanks.

I fly alot of solo IFR, and there is always some reason Mother Nature provides to carry more fuel, regardless of how I set my engine's power.

I put in the ER tanks from Hotel Whiskey in my 8. Takes approx 12 hours, can do it on a completed wing or finished aircraft, weight is just about on the CG, mounting points and vent system approved and tested to 9 g's by an FAA DER, very complete kit, adds 4.5 gals per side. Empty weight 13 lbs. Great company to work with.

Art in Asheville

I have tip tanks - Great!

If you are interested in range in an RV you need more fuel in my opinion. I have tip tanks (aluminum) on my RV-6A that are between the end of the original constant chord wing and the fiberglass wing tips. They extend the wingspan by 1.5 feet and aerobatics are prohibited but that is like telling me I can't have babies. They give me an additional 17 gallons and I used almost all of it in the AirVenture Cup Race this year. If you want it you should have it - You are building the plane for you! I thing the utilization of existing wing volume is the best way to go and if you want to do it you can do it. Kahuna's post gives some very good ideas. I assume this is still a two tank configuration. There are a lot of things to consider like filling the tanks and fuel management. Your sensor will top out before the tanks are full; if the fill port is not the high point you will not be able to fill the tanks; if you have 4 tanks with 4 fill ports with the outboards flowing into the inboards you will have to fill the inboards then cap them before filling the outboards; if you have selectable tip tanks and takeoff with partial fuel in one that is selected the engine will die as you climb out in steady state high angle of attack with all of the fuel aft of the pickup tube; if you use 4 selectable tanks you must think through all of the valving configurations possible and select one that is intuitive and fuel proof; etc. etc. I have 4 individually selectable tanks and I love it (wish I had 60 gallons). You sound like you are not intimidated by the task.

Bob Axsom

Kahuna said:

1. Ordered one extra tank skin and split it to each side & Used a butt joint with a doubler to attach the added skin.
2. Ordered one rear baffle and split it to each side
3. Ordered the appropriate ribs
4. Ordered the extra z-brackets

Click to expand...

Kahuna, how did you deal with tank attachment to the spar? The spar web seems pretty straightforward, but with a match-drilled spar it seems you might end up with swiss cheese on the spar flanges. Did you go with a non-match drilled spar (flange)?

dan said:

Kahuna, how did you deal with tank attachment to the spar? The spar web seems pretty straightforward, but with a match-drilled spar it seems you might end up with swiss cheese on the spar flanges. Did you go with a non-match drilled spar (flange)?

Click to expand...

That is exactly the problem that I think I will run into. I am definately not intimidated by the task of larger tanks. If I were to do this it would be one tank per side, just larger. the leading edge would be one skin. How do you say. the old Meyers factory is 45 minutes from my house and they have a large leading edge roller, and they do know how yo use it . I like one tank due to the ease of use with more fuel. More pluming just means more things that can fail. So now the only thing that I am running into with the design is the wing spar. I called vans to see if it is possible to get an old rv-8 wing spar that was not prepunched. they said no and now that is where I am at. Any ideas anyone. Brian

Any Ideas???

dan said:

Kahuna, how did you deal with tank attachment to the spar? The spar web seems pretty straightforward, but with a match-drilled spar it seems you might end up with swiss cheese on the spar flanges. Did you go with a non-match drilled spar (flange)?

Click to expand...

I just delt with the swiss cheese. I used the tank skin extention as the drill template and drilled the holes into the web where they laid.
The web strength is in the bend radius, so the flange can end up with as many holes as necessary to get it to work.

Best,

Another Option

Instead of a passenger, carry 150/6 gallons of fuel in a centerline optional tank placed in the passenger seat location. Use a 4 port valve (3 tanks) and burn on the center tank first. This is what Jon Johanson, and the other world travelers do.

Remove the tank when range is not needed (or you want to carry the 150 lb co-pilot and/or do aerobatics) and cap that tank position on the valve.

Kahuna, thanks for the replies. did you happen to take some pictures of the spar flange. If so would you be interested in sharing. Thanks, Brian

flyboykelly said:

Kahuna, thanks for the replies. did you happen to take some pictures of the spar flange. If so would you be interested in sharing. Thanks, Brian

Click to expand...

No fraid I did not

Long rang tanks

I have installed l/edge o/board tanks on my 7, I had originally planned to do as Kahuna did & drill through the spar but in the end used the spar as the template & back drilled the skins, this isnt as pretty as putting extra holes in the spar web but I figured it was stronger. As it is you need to drill a load of extra holes for the nut plates. I just used a tank sub kit from Vans, extra Z brackets & fixed it to the spar as per the i/board tank. I did need to moved it o/board 5/8" to avoid interfering with the tie down & aileron bellcrank. Moving it out a wee bit gives just enough room to mount the landing lights between the two tanks, but its a real pita fabbing up the gap with the landing light lense in it. It does give good access to the connections though. Mine drain into the main tanks with gravity. This setup gives 84 gals. btw Ken Scott has seen this & didn't like it one bit.

Stephen
RV7 Fitting Canopy Frame
N570Z (Reserved)
Eugene Or,

Thanks for the reply N57 OZ, did you happen to take any pictures of your wing, and if so would you be willing to share them. Your setup sounds really interesting. Brian

Access Covers to ER Tanks

We're now installing the SafeAir ER tanks in our RV7, and are puzzling over how and where to cut the access covers for the fuel caps. Does anyone have photos, measurements, etc that you could share?

Cheers
Steve