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Toobuilder
02-05-2013, 06:34 AM
If one were to take an existing HRII and do a glass panel retrofit with very thin displays like the Skyview, is it feasible to install an RV-3 or Pitts fuselage tank up front? Sure could be nice to add another 15 gallons or so to the total.

longranger
02-05-2013, 01:43 PM
Michael,

I'm not sure about behind the panel, but I added tank attach doublers to the outboard end of the spars for a 16 gallon auxilliary tank on each side, for 74 gallons total. I planned to follow Pat Tuckey's plumbing scheme (napwars.com/RV-8HTML/Fuel.htm). I got one tank built, then life changed, then my mission for the airplane changed, then the project changed... I still have the project stored in my hangar if you just want to come up and take a gander sometime.

Another option would be to add two bays to the stock design inboard tanks. Each bay is about 4 gallons. John Harmon can make you a set of tank skins up to 60" long (at least he could when I was looking into it 10-12 years ago.)

n816kc
02-05-2013, 01:54 PM
Check out the SafeAir1 ER tanks. They are an easy retrofit and work great.

safeair1.com/fueltanks.php

Toobuilder
02-05-2013, 02:38 PM
Thanks gentlemen. I'm not super excited about moving that much fuel outboard, but have not ruled it out completely. Also, I am definately a DIY kind of guy, so I choked a bit on the cost of the tip tanks...

IMHO, the Rocket is lacking in two areas in relation to the -8: Endurance and baggage. With the removal of steam instruments, there is going to be a bunch of "wasted" real estate behind the firewall. Turning that area into baggage requires a door, which has significant structural implications, so that kind of rules that option out. But it certainly could be used to give the airplane more endurance with a simple, classic, and well understood fuselage tank system. So I'm going to chase that rabbit until I catch it or it drops into a hole.

But I'm interested in a quick trip up to Tehachapi to scope things out. Thanks for the offer!

Snowflake
02-05-2013, 05:41 PM
By far the simplest solution is to just build the tanks one or two bays longer and put the fuel in the wings. Designing a fuselage tank will be a heck of a lot of work, and in the end you have a huge liability... Fuel in the cockpit in the event of an accident. Not worth the tradeoff, IMO.

smokyray
02-05-2013, 06:37 PM
Check out the SafeAir1 ER tanks. They are an easy retrofit and work great.

safeair1.com/fueltanks.php

Michael,
I had a set of Safe Air One tanks built by my friends Hollywood and Cheese in my HR2. It brought my HR2 total to 54 gallons (+10) with an added weight of 9.5 lbs, all forward of the CG with no G restrictions when empty. Once installed they are invisible except for the cool fuel cap doors in the wingtips. Along with EI electronic ignition and GAMI injectors, my econo-cruise range at 10.5 GPH/11,500' and 190 KTAS was just under 1000NM. My longest was Dallas to Lakeland FL, 825 NM and I landed with 9 gallons!

The flexibility, ease of use and peace of mind over bad weather, water or mountains at night is priceless. Highly recommended!
http://www.safeair1.com/fueltanks/rv4ertanks.php
V/R
Smokey

Toobuilder
02-05-2013, 06:41 PM
Snowflake -

Keep in mind, this is a retrofit to an existing airplane. Bigger wing tanks would be a lot of work. As for the liability of fuselage tanks, well, that's not exactly virgin ground. My Hiperbipe has 40 gallons right above my knees, as do scores of other Homebuilt and production aircraft. As a "limited use" addition (tank would be empty for local flying), relative safety would be midway between the many "full time" fuselage tanks and those with wing only tanks.

petervs
02-05-2013, 06:54 PM
I am building a HR II and also decided more fuel would be nice. I designed a removable tank to go in the rear baggage area, it is a rectangular box shape but is tapered to match the seat back angle, and holds 16 gallons. A small electric fuel pump transfers fuel to the left main when there is room. I installed piano hinges along the sides and front of the baggage floor and matching ones on the aluminum tank for easy in and out. Just connect the fuel drain line and vent.

I figure I will not be doing long leg flights with a passenger when we will need the entire baggage area, and when extra fuel weight in the baggage area would put us out the rear of the CG envelope. But for solo trips 100 pounds in the baggage area is OK. I can often make out and return flights without having to buy fuel. I am a firm believer that human bladder capacity has no relation whatsoever with the frequency of airplane refuelings!

smokyray
02-05-2013, 06:58 PM
I am building a HR II and also decided more fuel would be nice. I designed a removable tank to go in the rear baggage area, it is a rectangular box shape but is tapered to match the seat back angle, and holds 16 gallons. A small electric fuel pump transfers fuel to the left main when there is room. I installed piano hinges along the sides and front of the baggage floor and matching ones on the aluminum tank for easy in and out. Just connect the fuel drain line and vent.

I figure I will not be doing long leg flights with a passenger when we will need the entire baggage area, and when extra fuel weight in the baggage area would put us out the rear of the CG envelope. But for solo trips 100 pounds in the baggage area is OK. I can often make out and return flights without having to buy fuel. I am a firm believer that human bladder capacity has no relation whatsoever with the frequency of airplane refuelings!

Michael,
All of my Safe Air One tank installations were in 3 different flying airplanes. Needless to say after 3000+ hours, I like them...:)

V/R
Smokey

PS: Dave Anders mounted one of these in his baggage compartment: http://www.atlinc.com/BANTAM-series.html

Toobuilder
02-05-2013, 08:06 PM
Smokey - the safe air looks like an easy retrofit. The standard LE type tanks suggested in the prior post would be tough to retrofit, however.

Peter - on my drawing board is a "rocket type" airplane with the pilot in back. I planned on having a fiberglass tank that would drop right into the front seat bucket, secured with the 5 point harness. It would end up looking much like a department store mannequin torso, with the filler neck located... Well, at the top of the neck! With QD's on the supply and vent, it could be in and out in seconds. If you are doing a solo thing anyway, moving your tank forward a bit to the passenger seat would help the CG shift with fuel burn. You want to shorten that moment arm as much as you can. All that said, my Hiperbipe is the one and only "ER" model - it had a 17 gallon aux tank right behind the seat back for a total of 57 gallons... In a 180 hp airplane. To say it had long legs was an understatement!

longranger
02-05-2013, 11:27 PM
Michael,

I also missed the fact that you were starting with a finished airplane. Definitely too much work to fit larger or additional leading edge tanks. You're still welcome up to see what I did. Just give me a bit of a heads up to make sure I'll be around.

Toobuilder
02-06-2013, 06:55 AM
Yep, if I was building, the fuel would certainly go in bigger LE tanks or something like that. Definately the most elegant solution. Will give you a shout sometime in the near future. Thanks.

Thinking more about it, I think the fwd fuse tank could serve an additional function as ballast. Rockets are fairly limited in loading options, and the ability to load 120# of fuel well forward could add some flexibility. That is certainly one of the advantages of the -8...

...and then my neighbor, also a Rocket owner, suggested that the tank could easily double as a smoke tank. Not exactly practical, but what the heck?

Snowflake
02-06-2013, 07:19 AM
Ah, I missed that it was a rebuild too. I still think that the small additional effort needed to build new leading edge tanks would be worth it. The alternative is to be working inside a tight fuselage and setting up new and novel fuel connections with new fuel controls that will be non-standard compared to other RV's.

If you build new tanks, on the other hand, at the end of the day your system will be dead simple and just like every other RV out there... Just with a larger credit card bill when it pulls up to the pumps... :). Except for local flying you don't need to fill it right to the top.

The plumbing needed to make a header tank double as a smoke tank scares me. Accidentally putting fuel into the exhaust pipes or smoke oil into the engine would ruin your day in a hurry...

Toobuilder
02-06-2013, 08:26 AM
...The alternative is to be working inside a tight fuselage and setting up new and novel fuel connections with new fuel controls that will be non-standard compared to other RV's......

Well, consider that the whole top of the fuselage from firewall to instrument panel comes off with screws on a Rocket, so access is not a real issue. Also, it would likely be a sump type tank ("T" configuration, if viewed from the pilot seat), so it is a very short run of tube from the bottom of the sump, through a 90 degree bend aft to the existing fuel selector location on the fuselage centerline. The selector would be non standard only in the respect that it will have a "Center" position instead of "Off". I'm sure Andair makes a near drop in replacement in the port configuration I'd need.


The plumbing needed to make a header tank double as a smoke tank scares me. Accidentally putting fuel into the exhaust pipes or smoke oil into the engine would ruin your day in a hurry...

It's not the plumbing that is scary, it's the operation of the ship. I agree, that this aspect requires more than normal "aircraft specific" familiarity, but it's not like this Rocket is going to be used as a line rental at the local FBO. It will require some significant thought to try reduce the possibility of opperating "out of configuration" - absolutely agree.

It's not a major objective anyway... Just something fun to think about.

I appreciate all the comments.

rocketbob
02-06-2013, 08:37 AM
http://mstewart.net/super8/smoketank/index.htm

I copied Mike on this, but did not do the wing root area and have an estimated 72 gallon capacity in my F1 wings. Left tank is switchable between smoke/fuel.

Toobuilder
02-06-2013, 08:49 AM
Can't view the link yet, but I thought there was precedence for a dual use (smoke oil/fuel) tanks... I think some of the airshow performers use their smoke tanks for fuel during the ferry flights.

DanH
02-06-2013, 10:41 AM
Can't view the link yet, but I thought there was precedence for a dual use (smoke oil/fuel) tanks... I think some of the airshow performers use their smoke tanks for fuel during the ferry flights.

Just remember oil is pro-detonation.

petervs
02-06-2013, 01:12 PM
Hey Michael,

Your mannequin type fuel tank has already been done. One of my neighbors has one for his Bucker biplane. It is a bit eerie to see as it looks so human. And of course is held in place by the front seat belts.

Maybe you could also use it in the car so you can drive in the HOV lane?

Toobuilder
02-06-2013, 01:21 PM
Just remember oil is pro-detonation.

I'm guessing you're concerned with residual oil following the "airshow performance"? If so, I thought about that and agree it needs to be addressed. Initial thoughts are to make sure the tank can be drained completely through normal use (sump tank design should ensure this); and that the tank is serviced completely full with gasoline following the oil use. Any residual oil should dilute harmlessly in 20 gallons of fuel, I would think.

Toobuilder
02-06-2013, 01:24 PM
Hey Michael,

Your mannequin type fuel tank has already been done...

Yet another "original" idea that's been done before. Is it possible I'm not as smart as I think I am? :D

Caveman
02-06-2013, 06:09 PM
I planned on having a fiberglass tank that would drop right into the front seat bucket, secured with the 5 point harness. It would end up looking much like a department store mannequin torso, with the filler neck located... Well, at the top of the neck! With QD's on the supply and vent, it could be in and out in seconds.
...SNIP... To say it had long legs was an understatement!

Heck, just buy one of those heavy duty blow up dolls and use her for a bladder tank.


Sorry.....