Extended Range Fuel Tanks on a RV-8

I am looking for recommendations/opinions for extended range fuel options for a RV-8.

I am have considered the Johannsen tip tanks and the SafeAir ER Tanks, but I have decided to either use the entire leading edge as fuel tanks or to remove the outboard wing leading edges and install another set of Vans prebuilt fuel tanks. The latter option could preserve the possibility of normal aerobatic operation, I think. I do not know how difficult installing a second set of Vans prebuilt fuel tanks will be into a set of fast build wings.

All opinions, advice, information, etc. will be appreciated.

Thanks,
Robby Knox

Well, there are a couple of problems you're going to have to resolve if you want to do this, first of which is to find a suitable place to put your relief tube. ;-)

The major problem you're going to have with putting an extra set of tanks outboard is that the entire wing spar is already pre-punched for the leading edge and main skin rivets, and these things have very tight spacing...so there's almost zero chance of the holes in the pre-built tanks for the screws lining up with those holes.

The second problem I see is that if *I* were going to do this I would want to build up the spar in that area. The spars are built-up to about the point where the tank stops and the outboard end of the spar is basically the spar web/flange piece only...so I would not feel comfortable hanging 136 pounds of gas out there on that flange. Also, the tank attaches to a bracket on the side of the fuselage, which helps support it's weight, etc. Also the butt joint with the leading edge provides additional support.

I guess my question is, what are you going to do with the airplane? Are you going to be an earth rounder or are you simply interested in having a little longer capability?

A friend of mine is *almost* done with his -8 and he put a wet wing smoke oil tank in the wing walk area. That's something that I think could be considered if your mind is already made up.

It seems to me that the easiest setup would probably be the ER tanks. Installation seems very easy with very little modification to the plans.

All the best,

PLEASE... Don't go making modifications to the spar. The design of the spar has less to do with the fuel tanks than the span loading of the wing. The outboard portion of the wing carries less load than the inboard protion. This is why the spar tapers. If the outboard portion of the spar is beefed up you will transfer more loads to the inboard portion actually making the wing weaker than it is now. Don't go screwing with a good design without permission of the designer. The ER tanks by Hotel Whiskey are the smartest way to increase range on an RV. They are proven.
Mel...DAR

Buy ER tanks from Hotel Whiskey

Hotel Whiskey Aviation in McKinney, TX has engineered, designed and built enxtended range tank kits for the 4, 6, 8 and 10. They are tubular and slide into the lightening holes of the wing. The fuel (1 extra hour) is right on the ship's CG. The tanks and attachment have been signed off by an FAA DER, and have been sandbagged and stressed to 9 G ground testing. Flow testing in all attitudes and altitudes up to 12,000 feet have been accomplished. The venting has been engineered as well. They are designed to be retrofitted to a flying airplane. Total installation time approx 12 hours.

Oh, and the weight for the RV-8 is 13 lbs. The kit is the most complete retrofit I have ever seen for homebuilt or production aircraft (other than the installation kit for the Advanced Control System display). Small anti-bug screens are even included for the vents as well as placards for the instrument panel.

I did my 8 while under construction, Danny King has his installed in his flying aircraft. No difference to the RV's handling when empty and perfroming acro. When full, very very slight decrease in roll initiation, and no stick force changes.

There is rumored to be a feature article on the tanks in an upcoming Sport Aviation issue.

http://www.hotelwhiskey.com/

I do not work for HW, just a very satisfied customer.

Art in Asheville

HW Tanks

Thanks, I have a set of HW ER tanks installed in my current RV-8. I am looking more range for over water flights and do not like the idea of portable tanks in the cockpit. I agree that the HW tanks are great, but I really need at least double their range. The Johannson tanks have around 22 gallons, but I do not see how the end wing structure can support that weight? Thanks for the responses and input. Any additional thoughts, info or opinions are appreciated.

Robby Knox

Robby:

A friend (and hangarmate) of mine just removed the baggage compartment aux tank from his RV-8, since he has never used it on several years of flying. It fills the entire lower part of the baggage compartment and holds IIRC 21 gallons.

If you're interested he is willing to sell the tank--it would be a relatively simple retrofit.

What would it take to build or modify an 8 for a solo across the "pond"?

Assuming the "pond" is the Atlantic, you need about 1000 statute miles of range (St. Johns Newfoundland to Narsarsuaq, Greenland) PLUS whatever reserve you're comfortable with. A removable tank bolted in place of the rear seat should do it. If you don't like the idea of storing fuel in the cockpit, check here and see how Pat Tuckey did it.

Bill Randolph did it in 2005

Californian Bill Randolph built an RV-8 with some mongo extended range tanks and then flew it around the world in 2005. He had stock wing tanks, along with a fuselage tank in place of the rear seat, as well as a tank in the front baggage compartment. That tankage was sufficient to get him from Honolulu to California (the longest leg).
On another note, Georgian Mike Stewart just finished a new set of wings for his Super-8 with four stock 21 gallon tanks. He mounted two additional stock tanks just outboard of the standard ones. Others have done likewise.

Here is mine



These are on our RV-6A in cruise configuration 8.5 gallons added to each tip, 17 gallons added total. We have flown with these for 7 years with no problem. I personally think your approach is a good one in that you are not changing the aircraft envelope. These tanks (which were developed by Farn Reed and are no longer produced) add 1.5 ft to the wing span and they cause Mr. Van concern. This configuration is not an option because they don't have sufficient capacity for what you want to do and the commercial product is not available but it does hint that the wing is sufficiently strong to handle the ~ 71 pound load hung on the end of the wing during routine operations.

Bob Axsom

Modified Tuckey Tanks

I am doing a modified (smaller) version of the 'Tuckey tanks'...just finishing them up now. This is my blog entry regarding my thought process before embarking on this, including a link to the Tuckey tanks which I used as my model.

Just a couple notes. I havent kept good financial records on total cost but it is more than the cost Mr. Tuckey quoted in his analysis. His figures might be a tad outdated and the deluxe fuel caps blow that figure up quite a bit. Its a fair amount of extra work--you will be pretty tired of doing fuel tanks after you do four of them. But, once you understand the design concept its pretty straightforward to do leading edge tanks.

Tip Tanks

I put the Johannson tip tanks onto my RV-6A, and now have them on my RV-7A (home built as Johannson's are no longer available). They are direct plumbed into the main tanks. The main tank also uses the tip tank vent (Original main tank vent capped off) with an alternate tip vent inside the wing on a check vlave. Total capacity on the -7A is sixty gals.
I have pictures if you need them...

N62XS said:

Thanks, I have a set of HW ER tanks installed in my current RV-8. I am looking more range for over water flights and do not like the idea of portable tanks in the cockpit. I agree that the HW tanks are great, but I really need at least double their range. The Johannson tanks have around 22 gallons, but I do not see how the end wing structure can support that weight? Thanks for the responses and input. Any additional thoughts, info or opinions are appreciated.

Robby Knox

Click to expand...

Fred
I'd like to see the pictures.
John