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Extended range fuel tanks

marv1121

marv1121

Well Known Member
I have a flying (not under construction) RV-4 and would like to add a little more fuel capacity to it. This is because I fly with several RV-7's and 8's and if they want to stretch their range I am not able to keep up. I have read about 3 different methods of doing this and the idea I like best is making the fiberglass wingtips into fuel tanks.
At a fly-in I have seen a RV-4 that had extra fuel but never found the owner of the plane.
Has anybody out there done this modification and do you have any tips on doing it.
 
There are many threads on this subject. Several commercial and one off solutions as well. A search should provide plenty of reading material
 
WhiskeyHotel extended range tanks.

I have the WhiskeyHotel extended range tanks in my -4 which gives me an additional 8 gallons of fuel...(40 gallons total). It?s a pretty easy solution to extend your range by quite a bit.

Mark
 
You could make some "Drop Tanks".

These are baggage pods but there is no reason why you couldn't make them into removable fuel tanks with an electric pump to lift the fuel to your mains.
rvpods.jpg
[/QUOTE]
 
Marvin,


If you subscribe to Kitplanes (or have a friend who does), there is an article in the January 2019 edition on an aux tank project. It goes in rear seat area which only works when you fly solo but its an easy weekend project.
 
marv1121 said:
I have a flying (not under construction) RV-4 and would like to add a little more fuel capacity to it. This is because I fly with several RV-7's and 8's and if they want to stretch their range I am not able to keep up. I have read about 3 different methods of doing this and the idea I like best is making the fiberglass wingtips into fuel tanks.
At a fly-in I have seen a RV-4 that had extra fuel but never found the owner of the plane.
Has anybody out there done this modification and do you have any tips on doing it.
Click to expand...

Send me your phone number. I have a friend taking his RV-4 wing tip tanks off because his blader is not compatible.

Break

I had the wiskey hotel tanks on my old -4 and they worked well. I built rocket tanks for the -4 I have now. That works even better.
 
N941WR said:
You could make some "Drop Tanks".

These are baggage pods but there is no reason why you couldn't make them into removable fuel tanks with an electric pump to lift the fuel to your mains.
rvpods.jpg
Click to expand...
[/QUOTE]

Is the existing tie-down the main load bearing attach point? May I assume theres a secondary attachpoint further aft for side-side stability but much load bearing? If so, how far aft?

Bevan
 
Bevan said:
Is the existing tie-down the main load bearing attach point? May I assume theres a secondary attachpoint further aft for side-side stability but much load bearing? If so, how far aft?

Bevan
Click to expand...

It does pick up the tiedown on the bottom side and there are two nutplates on the topside to hold it in place. (I was thinking of adding rivnuts on top since access to the leading edge is a pain on a flying airplane. Although that area might be accessible once the wing tanks are removed.)

Keep in mind, as depicted in that picture, they are extra baggage compartments and have a number of screws to remove the front of them. The only pair I have seen are on a -6 as they are no longer made. (If you are going to make a pair, let me know and I'll get the dimensions for you.)

My thinking was to make the aft section (tail cone) removeable and hide the fuel pump in there, the vent would come out of the column, halfway between the bottom of the wing and the "tank". Quick release fuel and electrical fittings would make it removable. I would use either the standard Van's fuel cap or contact the canard guys to see what they would use.
 
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YouTube

Is the existing tie-down the main load bearing attach point? May I assume theres a secondary attachpoint further aft for side-side stability but much load bearing? If so, how far aft?

Bevan[/QUOTE]

If I recall, not too long ago someone posted a YouTube link on the build of the under wing pods.
 
I used to think drop tanks would be easy; after a bit more thought I'd consider the path of most resistance. You need to know how to shape them to neutralize lift/weight, taking into consideration the wing/tank gap, keep them stable (both load and flutter) in all conditions (slips, etc) deal with varying cg conditions, etc. At any rate, here's a master building baggage pods.

https://www.youtube.com/watch?v=H5A7_oPAw9c&t=3s

Charlie
 
Marvin,

I have Hotel Whiskey Aviation extended range tanks and love them! I highly recommend them if you want to add an additional 8 gallons of fuel (4.1 each side). Simple, affordable you can?t beat the value of the added extra fuel.

PM me if you have any questions.

Myles
 
mbert said:
Marvin,

I have Hotel Whiskey Aviation extended range tanks and love them! I highly recommend them if you want to add an additional 8 gallons of fuel (4.1 each side). Simple, affordable you can?t beat the value of the added extra fuel.

PM me if you have any questions.

Myles
Click to expand...

I like the Hotel Whiskey tanks but please tell me this is a type-o:
Hotel Whiskey said:
Pricing:
ER Tanks for the RV-8* are $2575.00 + Crating, Shipping, and Insurance. This typically adds $500.00 to the total cost when shipping within the contiguous U.S.A. Tanks picked up by the customer, or shipped to addresses within the state of Texas, are subject to 8.25% sales tax. We DO NOT accept credit cards for ER Tank purchases. Personal checks, bank checks, or money orders are fine.
Click to expand...
* This was snipped from the RV-9 page, even though it states RV-8.

The prices are as follows:
RV-4 $1850
RV-6 $1850
RV-7 $1650
RV-8 $1750
RV-9 $2575
RV-10 $1750
RV-14 Coming soon

Why are the RV-9 tanks $925 more than the RV-7 tanks when the structures are virtually the same?

Their website says the tanks are more difficult to install in the -9 but doesn't mention what the issue is.
 
rv7charlie said:
I used to think drop tanks would be easy; after a bit more thought I'd consider the path of most resistance. You need to know how to shape them to neutralize lift/weight, taking into consideration the wing/tank gap, keep them stable (both load and flutter) in all conditions (slips, etc) deal with varying cg conditions, etc. At any rate, here's a master building baggage pods.

https://www.youtube.com/watch?v=H5A7_oPAw9c&t=3s

Charlie
Click to expand...

The sad fact about drop tanks is they are most effective when you actually drop them as soon as they are empty. This gets expensive! The extra drag of the tanks means much of the extra fuel is wasted by the increased drag over the length of a entire flight.
G
 
https://www.youtube.com/watch?v=a9_TqOB6_Jk link shows Tom Hunter & his T-18 'drop tank' that does not drop. 3.7 gallons if I recall.
I'm making an aluminum under wing tank now. It's got an 8" aluminum prop spinner for the nose and rolled sheet for the body & tail fairing. I'm cutting parts now.
It will hold about 6 gallons. I've been making drawings and cut-sheets for the parts.
I plan to rivet it together and make it fuel tight by brazing it with ATS-2000 rod and a propane torch to avoid using Proseal.
Tests with the brazing have gone well, including over the rivets of the parts I assembled.
This project has been a lot of fun for me, but I don't recommend it. The tank volume will always be less than you want (I was looking for 1 hour - 8 gallons)
but that would be a big long or fat tank that sticks out the front or hangs too low...Then you need to add attach points to bear the weight and drill/install the bushings and tubing etc. through the wing ribs & into the fuselage...etc.
Others on the site (John Thocker comes to mind) have installed temporary tanks using a Race Car fuel cell in the rear seat area or baggage compartment. I think this is the most practical solution. Otherwise, building extended wing tanks is probably best.
http://www.vansairforce.com/community/showthread.php?t=96010
I also have a Thorp T-18. These have a single 29 gallon tank that only seems to take 27... a bit small on those long trips.
 
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