ER tanks for RV-9A

[beechrv9a]

Safeair (Hotel Whiskey aviation) has not developed the ER tanks for the 9a yet. Has anybody else installed extended range tanks? I installed the fuel bung with a plug on the fuel tanks when building them, and I am ready to store the wings now. I was hoping to complete this before storage. Suggestions?

 

[Mel]

I have a -9A (project) in my shop that has tip tanks. They hold about 8-9 gals each. The tanks were built by Mr. Wilhite. They are very nicely done, but have not been put into service. Hotel/Whiskey will build ER tanks for the
-9 if there is enough demand.

 

[Pilottonny]

Long range for RV9

I built long range tanks holding a tested total of 204 lt, against 136 lt. original. I extended the tanks by 3 bays, using extra tank ribs, extra tank skin, extra Z-brackets, omitting part of the leading edge skin and 3 leading edge ribs, etc. The total extra empty weight per tank is only 1.200 gr, which is really peanuts. For the extension I used tank skins without the prepunched holes and match drilled them from the original tank skins and the spar flanges to get the right hole spacing to mach the holes in the spar flanges for the platenuts.

I got the "blank" tank skins from Vans as a one-off, they will definitely not do this for USA builders, because of the "Catfish" !! ("What is the difference between lawyers and catfish"??, see other post about Lycoming of today!)

The beauty of it is that you need no additional plumbing, additional fuel monitoring, additional filling caps, switching/pumping from/to tanks, additional drains, etc., etc..

Regards, PilotTonny.

 

[beechrv9a]

ER tanks for 9a

Thanks for the reply. My tanks are already sealed and tested, so I am looking for the "tube" type er tank or something to fit in the fuselage. Who is Mr. Wilhite and how do I get in touch with him.

 

[mtodd615]

ER Tanks

I am also building a RV-9. I have all ready finished my tanks and was thinking about more fuel. I e-mailed Safeair about ER tanks for the RV-9. They stated just last month that there are plans for ER tanks for the 9 and are looking for a RV-9 for the prototype. Since I am several years from flying at my pace I did not offer. I would be interested in the tip tanks from Mr. Wilhite since they would hold more fuel.

 

[Mel]

Charles Wilhite is located at Hick Airfield in Ft Worth, He is the one building the carbon fiber canopies recently featured on this forum. I don't have his contact information. You may be able to get it from Jay Pratt.

 

[airguy]

Wait, wait, wait - the same guy that can't get the carbon fiber canopies out of his shop and won't talk to his customers?

No thanks - I'll build my own ER tanks.

 

[Mel]

I wasn't trying to advertise for or against Mr. Wilhite. These tip tanks were done several years ago before he got into the canopy business. I was just answering the question of who and where is he. Yes, he was difficult to get a hold of then too. I'm just saying that once he did the job, he did a great job.

 

[beechrv9a]

Thanks for your help

 

[Pirkka]

ATTN: Pilottonny

Hey PilotTonny, you have refused to accept personal messages (PMs) and e-mails. I'm interested doing similar ER tanks as you did, but for RV-7. Would you contact me for futher details how you really did it. Thanks!

 

[Pilottonny]

Hello Pirkka,

As I explained before, Vans do not promote this and supplied the necessary material to me as a 'one-off', only. But, since you are in Finland you can always try (The Yankee lawyers like to get their teeth into these kind of changes to the design if anything goes wrong, even if it has nothing to do with the accident).

What you need (for the RV9) is a rear tank baffle, which you cut up in half and use for both tanks, two unpunched tank skins, 3 extra tank ribs for each tank, 6 extra Z-brackets, 6 extra tanks stringers and the necessary plate nuts and screws (and extra pro-seal!). The joint-plates for the tankskins and baffles are cut from left-over tank skin. The unpunched tank skins are necessary because you have to match-drill the holes from the spar into the tank skin, for the screws, the original holes will not match!

If you are able to get the materials, I can give you some pointers how I did it (might be different on the 7!)

Good luck, PilotTonny.

 

[Kahuna]

I used the technique above on my 8.
Went 2 extra bays. From 42-60 gallons. Flying 400 hours . Works.

 

[tloof]

ER Tanks

For US built RV's it would be way simpler to just order all the materials for building 2 new tanks (just tell Van's that you are rebuilding new ones because the 1st ones didn't come out so well) and then build an entire 2nd set that are independent of the inboard tanks so that the fuel capacity is doubled (that would make for the ultimate in extended range!). With the 2nd set of tanks mounted outboard you would normally keep them empty for aerobatic flight on an RV7 or RV8, but fill them for long range cruise flights only. Just tube up lines to the 2nd set down to an ANDAIR 5 position fuel valve so that you can turn the valve to each tank separately as needed (this way only one boost pump is all that is required). You also will need to run another seperate vent line back to the fuselage in the same fashion as the main tank vent lines. The 2nd extended range tanks can be mounted to the spar in a similar fashion as the original tanks (this will require adding a 90 degree angle riveted on the original spar for attachment as I recall).

 

[Captain Avgas]

With the 2nd set of tanks mounted outboard you would normally keep them empty for aerobatic flight on an RV7 or RV8, but fill them for long range cruise flights only. Just tube up lines to the 2nd set down to an ANDAIR 5 position fuel valve so that you can turn the valve to each tank separately as needed .

Have you actually flown the above fuel selection configuation or is this just theory. I have a friend who used the Andair 5 way fuel valve in a similar set-up. He says when the fuel first ran out in the aux tank it took over 10 seconds of dry pumping for the engine to start again.

If I did that with MY wife in the plane it would be the last time she'd fly.

 

[airguy]

I like that setup much better than scratch-building a single longer tank. I personally would put a couple fuel pumps on the outers to pump into the inners on a momentary switch, but to each their own....

 

[Pilottonny]

More tanks = extra weight + complex

Do not forget if you are building additional tanks you will need a lot of extras: 5-way Andair valve, 2 additional feed lines, 2 additional vent lines, 2 additional filling caps, 2 additional drains, 2 additional fuel senders and 2 additional gauges. Also you will have 4 more tank end-ribs. If you are using an Injection engine you will also need 2 additional return lines and a double stack 5-way valve. The total will be a lot of weight! My tanks only weigh 1,2 kg more, each, than the original ones and operate exactly the same (just last longer)

Also the complexity of the system may cause operational mistakes (switching to an already empty tank!?)

I do not know how it is with the 6, 7, or 8, but you will not be able to use the original tank skins of the 9, even for an additional tank, because the hole pattern will not match the spars and the tank ribs may be in the wrong position. That is why I used unpunched skins and drilled all the holes my self.

Happy building, PilotTonny

 

[Pirkka]

Hello Pirkka,

As I explained before, Vans do not promote this

No doubts, but this is what experimentals are for -- experimenting. This is shame that in States their concern is law suits. Stupidity should be punished instead of the manufacturer.

What you need (for the RV9) is a rear tank baffle, which you cut up in half and use for both tanks, two unpunched tank skins, 3 extra tank ribs for each tank, 6 extra Z-brackets, 6 extra tanks stringers and the necessary plate nuts and screws (and extra pro-seal!). The joint-plates for the tankskins and baffles are cut from left-over tank skin. The unpunched tank skins are necessary because you have to match-drill the holes from the spar into the tank skin, for the screws, the original holes will not match!

Now I'm getting how you did it. Actually only thing you are not saying (if I'm following) that the "tip" skin have to be cut also from about the middle to make room for the new tank. And instead of one joint in the leading edge you'll now have two.

For RV-7, there is tank baffles (T-702-x) for both sides which for RV-8 and 9 there is only single item.

As RV-7, 8 and 9 has all different wings and this kind of modification has been made for the 8 and 9 would someone be able to scan and email / PM link to the image of the wing section of the drawings (RV-8 or 9) for comparison? What I'm looking is that is the only actual difference the profile shape and length of the wing or are there any other things should be noted.

How about the capasitive sender -- is the normal sender ok when having bigger tank?

Good luck, PilotTonny.

And you think it's luck? I thought it was the money they ask for... But I don't mind if you send some pictures already. I'll have to take a look or the drawings closely and maybe delay an order a while until I've figured out every detail.

Edit: To be precise, in the first message you said that you omitted some skin and ribs.

 

[Kahuna]

So in my case I just extended the mains 2 bays by adding to the existing tanks. There is no problem with the capacitive senders. They will work fine no matter the tank length.
I stared at the plans and decided I could order 1 extra tank skin (split it in half and use some on one side, some on the other), 1 rear baffle (again split and use on each half), the appropriate ribs and z brakets, fill/patch in any holes (like the existing filler hole had to be patched and a new one made 2 bays out), butt joint everything with doubler strips and be in good shape. It was pretty cheap, and allowd for the simple no extra plumbing. Was quite easy to do.
No I dont have the parts list. If you sit and stare at a set of tank plans for a few minutes, it becomes clear whats required.
Best,

 

[Pirkka]

So in my case I just extended the mains 2 bays by adding to the existing tanks.

I've been considering also that two bays would be plenty of extra. That should also save one tank skin (~$95) as you said. However at time you ordered your skins, they had no prepunched holes?

I don't have my plans here (I'll get them tomorrow), but I've been looking for Van's part list. It' s pretty clear what is needed, but my worry is the predrilled holes. I sent my first question to Van's support about this issue and the feedback was... well... I didn't get much further with them so here we are on our own.

If they are not willing to sell non-prepunched skin, how hard it would be bend sheet to wing skin form? I quess pretty hard. Is there real difference with left or right tank skins as they have separate part numbers?

"[...] butt joint everything with doubler strips and be in good shape."

Yes... stiffeners like in normal tank, but did you have some other doublers as well? And I found something about butt joints from Wikipedia, but not getting picture right now.

I'll have to look my plans tomorrow with time... Thanks already for everyone for their help.

 

[Pilottonny]

A drawing tells more than a thousend words!

Hello Prikka,

Yes, obviously you cut and omit the part of the leading edge skin (and the appropriate amount of ribs) that you are extending your tanks. And yes there will be 2 joints, one between the two tanks skins (with a joint plate on the inside of the tank, all prosealed in) and one between the tank and the leading edge skin, like the original setup, but only further outboard. As a matter of fact the tank skin will make up some of the extra weight, because it is thicker than the leading edge skin that you are omitting.

As Kahuna said, look at the drawings and imagine the tanks to be longer, it should get clear to you. Also consider any lightening holes in the spar (they may be different to the 9) where you want to put your additional Z-brackets.

Sorry I do not have digital pictures of the tanks.

I do not think its all about money. I guess, making the unpunched tank skins will upset the Vans-manufacturing process quite a bit and therefore they are not keen on "selling" you these items, even if you pay more for them than the original and punched tank skins (as I did).

Regards, PilotTonny

 

[N523RV]

LR Tanks

I've been flying 160 hours now with long range tanks identical to what PilotTony did. Not sure if he got the idea from me or not. The only difference is that I used a single piece to the whole leading edge.

You can look to see how I did it on here.

Here is a picture before it was closed up, but this is the best shot I have.

 

[Low Pass]

I've been flying 160 hours now with long range tanks identical to what PilotTony did. Not sure if he got the idea from me or not. The only difference is that I used a single piece to the whole leading edge.

You can look to see how I did it on here.

Here is a picture before it was closed up, but this is the best shot I have.

Very impressive!! What are you looking at, 2x, 2.5x the normal capacity?

On a slightly different note, I wonder if the foam used in race car fuel cells might help with the spraying problem when a tank ruptures during an impact. Surely it would be compatible with 100ll.

 

[N523RV]

I added 3 additional bays on each fuel tank, so each side has 27 gallons, 9 gals more than stock.

This modification, while tough to do, has turned out to be very nice. I don't often fill it to the top but have on several occasions where we are doing long trips (LOE '06). I normallly carry maybe 40-45 gals.

Good example is this weekend, we are planning a trip to Illinois to visit family. I'll fill it up at $2.91/gal before we leave and be able to go up and back (~2hrs each way) and still have reserve.

Very impressive!! What are you looking at, 2x, 2.5x the normal capacity?

On a slightly different note, I wonder if the foam used in race car fuel cells might help with the spraying problem when a tank ruptures during an impact. Surely it would be compatible with 100ll.

 

[jarhead]

...I wonder if the foam used in race car fuel cells might help with the spraying problem when a tank ruptures during an impact. Surely it would be compatible with 100ll.

A lot of off-road vehicle builders who use racing fuel cells are having problems with the foam coming apart and clogging the filters/pickups/pumps after a while. The issue is apparently with the additives in pump autogas - racing gas doesn't have these problems AFAIK. It's definitely something I'd recommend experimenting with on the ground with avgas, before even considering doing one tank for in-flight.