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Aux fuel

bobmarkert

Well Known Member
Does anyone have any thoughts on the HW auxiliary fuel tanks for the RV8? I talked to Danny King and he is sold on this, but I believe I will pay a significantly higher price than he did seeing how he was first. When it?s all added up it will be about $2,000 for approx 9 more gallons and 13lbs more weight. I don?t mind spending my money, but I hate to waste it. What does the tribe say???????? Specifically from those who have them/considered them and rejected the idea. I almost ordered today but stopped to ask this esteemed group!
Thanks
Bob
303 882-7410
RV-8 slow build
tanks
 
We have them on our RV-4 but we were a little more fuel challenged than the RV-8. (only 32 gal before)
We use them for our cross country trips. Without them, it seems like we are always a little low on fuel to make it to the less expensive fuel stops. Having the tanks also gives us more leeway when diverting around weather or making changes in flight.
They have been installed for 2 years with no problems and we love them.
 
I've used them in my RV-10, and really like them. I also put the Johansen one's in the RV-6 that Van was selling a few years back. For cross-country trips it's nice to have some extra fuel and pick your fuel stops, especially with the escalating price of fuel. I have installed them in the new RV-10 I am currently building, too.

Vic
 
I installed them on my RV-10 and am very happy with them. High quality kit, good instructions, and good customer support.
 
I've done it or doing it 3 times!

I had the HW tanks in my RV-8. Great to have your legal reserves out there. I have a set installed on my new Rv-6A and we are currently installing a set in my RV-10 wings. HW and the SafeAir1 guys are great and will stand behind the product. The product ads about 1 hour of flight time or about 175 miles to your range. This is one of the best add on products you can buy. I'm a happy customer three times over. Buy a set!
 
Since you asked for (humble??) opinions.. I'll offer mine too -- I think they're not needed (hence they'd be a waste of money). I don't need 'em because my plane has just enough range with standard tanks and I don't need any more.. (5.7hrs/900nm to dry).. At about 4 hrs, I'm just about done and prefer to take a break :)

However, whether you need 'em or not is something only you can answer based on what you're trying to achieve... Are you planning on 7hr (~1000nm) non stop legs? If not, then you don't need 'em. Are you in the 150kt @ 10gph club? If yes, then you may need 'em to make any reasonable xc trip....
 
HW Extended range tanks

Radomir,

Recheck your numbers, because they simply don't add up. With the HW extended range tanks, the RV-7/8 will hold 51 gallons. At 10 gph the endurance would be 5 hours to empty.

With the original 42 gallons the endurance at 10 gph would be less than 4+30. A prudent pilot will not fly with less than one hour remaining. That gives you less than 3+30 endurance.

Fly at low cruise, of say 8.5 gph and plan to land with one hour of FOB and your endurance will increase to 3+54. I don't know of any RV-7/8 that can fly even 800 nm, no wind, in less than four hours.

The HW tanks have proven to be a very useful addition to the Doll. The empty weight of most aircraft tends to increase with age. (not unlike the pilot) The HW extended range tanks have been the best 13 pounds the Doll has gained in the last nine years.
 
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Danny, I don't burn 10gph in cruise :) that would kinda suck...

Just some longer legs that I can remember off of top of my head:

Miami->Charlotte: 570nm 3:45hrs... ~13gal FOB (unfortunately no tailwinds helping)
Seminole,Tx->Casa Grande: ~500nm 3:26hrs 19.3FOB (5-7kts headwinds and yes, that's nearly 1/2 tanks remaining after almost 3.5 hrs of flying)

and a few others just like that. (I got receipts :))

But as I said, about 4 hrs is all I wanna sit in that thing... Usually my bladder starts suggesting we land even sooner :)
 
I added long range tanks to my old "big engined" Grumman Yankee years ago. The stock fuel gave you about 2+45 to dry tanks, which meant you had two hours endurance with minimal IFR reserves (forget divert fuel!). Adding gallons of fuel give an additional 1+30 of cruise time - those ten gallons basically doubled the useful range!

I haven't added the extra tanks to the -8 because it has a lot more to start with, so the percentage increase isn't that large - but it is very tempting. Under the right conditions of "tool boredom", I could see myself pulling the wingtips and adding them - if for no other reason, avoiding that long descent and subsequent climb for a fuel stop in the middle of a long trip. That's what piddle packs are for.....;)

Paul
 
psycology

I can't comment on the specific product but I'll share my reasoning behind adding the Johansen (sp?) tip tanks to my almost-flying 7A. They add 12.5 gallons per side for a potential total of 67 gallons.

One of the regular trips I plan to do is from the SF Bay area to Sun Valley Idaho. Back of the napkin no-wind enroute times are around 3 hours. I try to be as conservative as possible in guesstimates, so I estimate 10 gph burn and call the 7A a 3 hour plane with 1 hour reserve so the regular Sun Valley trip is really on the border of my non-stop comfort range for fuel reserves.

Here's where the psycology comes in. Consider a return trip westbound into moderate headwinds. That would mean a fuel stop. Probably somewhere on the lee side of the Sierras. Images of my wife come to mind, turning various shades of green with winds flowing over the peaks and getting kicked around just because we have to refuel. "Well we've really got 4 hours fuel, lets just get home." Skip the refuel stop. "Let's climb to get over the bumps." More fuel gone. Wife still feeling crappy. "I'll get us home quicker". Push the throttle in. More fuel gone. Baaad pilot.

I want to do everything I can do now, to avoid the devil on my shoulder getting me into trouble like that. I can avoid that simply by adding fuel capacity. Look at the forecast winds. If they're cutting into my range for an easy non-stop flight, add the fuel 'cause I built in the capacity. I might even just simply make it a policy to use the tip tanks on the west-bound leg in case the winds aloft are stronger than forecast.

It also happens to be one of the cheapest "speed-mods" you can make. Any trip that would require a fuel stop that you eliminate is like building a MUCH faster plane:)

I only intend to use the tip tanks for very specific trips. They weigh 11.5 pounds each. I don't know what the regular tips weigh but this is the kind of weight gain that I have decided is just fine.

For what it's worth...

Jeremy
 
OK, I'm finally on board!

Most everyone here knows that I don't normally jump in to be the first on anything.
Well Jeff and Chuck (Hotel Whiskey Aviation) have finally convinced me to "join" the crowd. I'll be installing their extended range tanks within the next few weeks.
While Ann & I don't do a lot of long cross country flights, I am very conscious of what I pay for fuel. Add the fact that I don't have fuel at home and it just kind of adds up.
I've known Jeff & Chuck for quite some time and they are a couple of the best guys around. To say nothing of the fact that their craftsmanship is unsurpassed!
 
Aux tanks

First off, someone stated that the Johansson tanks would add 12.5 gals per side. Not quite right: they add about 9.5 gals per side. I had them on my last RV-6A.....
Since Johansson no longer provides these tip tanks, I had a set built for my RV-7A. They were built from an existing set of RV-6A tips and required that the insides be re-glassed with the proper epoxy and glass to make them fuel resistant. Otherwise, they are the same as Johansson's design.
I have since helped another RV-9A owner construct a set of tip tanks for the RV-9A. With Van's permission, (he owns the molds) we had Van's supplier construct a set of RV-9A tips using the proper fuel resistant epoxy and glass (the stuff Easy's are made of..), then added the required baffling, lighting chambers for lights, wall, and electrical tube. Adding bunges for fuel drains, vents, etc. was just another detail.
An interesting note on how to get the tanks to fit exactly to the wing shape. We mounted the tips to the wings, then installed exterior forms to the outside shape of the tip to hold the shape after removing them from the wings. Then installed legs on the forms to allow working on the tips on the bench.....
If anyone is interested, I have some pictures of the RV-6A tanks being constructed. Email me direct at [email protected] ....
 
From Fred

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For me

Those tube tanks are too much money for too little fuel.

If i get REALLy bored I might make a set of tucky tanks for about 300 bucks or so, that should give roughly 10 to 15 gallons per side.

For me its all about cost..i have a regular 6 hour cross country and pay $3 a gallon for premium autofuel and 100LL is spendy as heck between here and there.

But even 300 bucks and having to cut into a flying airplane is hard to do..:)
 
RV-10 Leading edge tanks

Can anyone give me some info on a guy in Oklahoma that does the leading edge mod to give an additional 30 gallons per side on the 10.
 
Bob, this is the first I've heard of the HW auxiliary fuel tanks. Can you share a website so I can learn more?

James Hawkins
 
What about leading edge tanks?
I understand that a few builders have added additional stock type tanks outboard of the stock tanks?
That seems like the lightest solution, if you are still building your wings?
 
A local builder extended the stock tanks by getting some sheet stock and forming his own leading edge skin that was an extra rib bay (or maybe two bays? I forget now) longer. Then he just built a longer tank. This was on an -8. That's the best way to increase the capacity, IMO... The weight is closest to the fuselage, closest to the spar, and requires no additional fancy plumbing.
 
12.5 gallons per side

hey Fred
It was me that said 12.5 per side and it is correct.
I too didn't believe it until I measured it and I measured it VERY carefully. It might be that the difference is that these are the " bat style" tips,
so yours maybe a different shape. I agree that you don't want to take anyone's word on something like fuel capacity...MEASURE IT, and I did.

Good to have the reality check...thanks for the concern

Jeremy
edit-just checked your terrific work in the photos and they are indeed the old (and maybe new again) shape- mine are the different bat style tips
 
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I added leading edge aux tanks to my -7 (not yet flying) by following the example of some -9 builders that *are* flying. One of them is an engineer, so that helped with the comfort level.

I made the middle bays of the outer leading edge 'wet' using the stock components, leaving the outer bay and the bay next to the main tank dry. I added stiffeners to the bottom of the leading edge skins, similar to the original tanks, and covered the lightening holes in the spar to use it as the back baffle of these aux tanks. Calculated capacity was a little over 12 gal per side based on 'per inch' numbers for the stock tanks. It now appears that I have a bit more than that; I think I forgot to allow for that extra space between the stock baffle & the spar. Total added weight, including all fittings but not including the tubing or additional fuel selector, etc, is about 2 lbs per side; basically the weight of the quick drain, fuel cap, extra aluminum to close the rib holes and spar holes.

Cost, IIRC, was under $200 total, but was a *lot* of extra work, because I was basically making design decisions as I progressed (no plans to work from). I didn't change rib spacing because that's worked for others, and the aux tanks (and the plane) will be treated as standard category when they contain fuel.

My motivation is purely 'tankering'. My wife's limit is about 3 hrs (hoping she can extend that to at least 3.5 for what will be a recurring trip). But we have wholesale avgas on our airpark, and I intend to add a premium mogas tank (my a/c engines have always run better/cleaner on mogas). At a $2-$3 per gallon price spread, if I can tanker enough to make a round trip on home field fuel, I can pay off my materials cost pretty quick. I wouldn't have even considered $2k for aux fuel on a -7/-8; the cost/benefit ratio just wouldn't be there for me at that price.

Charlie
 
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