Hatz Biplane Association

Thinking about another fuel tank besides the top wing tank. Seems to me I can get a 15 gal. tank fairly easily behind the firewall in the fuselage. Any thoughts on this would be appreciated. Wondering about c/g balance issues and whether a smaller tank would be smarter.

I put a second tank behind the front seat instrument panel and on top of the cross brace. I lost the glove box but gained five gallons of fuel which increased my range by thirty minutes. The tank is an odd shape so that it would fit in the space and wasn't easy to make. I put the fill neck on the centerline of the fuselage and between the front windshield and the roll wires. I have not had any problems with C/G and I need a step ladder to fill it.
A friend put a ten gallon tank under the cross brace and over the passenger's feet. With his O-320 he gianed forty-five minutes range. He put his fill tube on the right side of the plane where he could fill it from the ground. A problem he has is the fill tube is so long that he has to be really carefull when filling or fuel will "burp" up through the tube and spill onto the outside. He has had no problems wit C/G either.
I plumbed mine so the tanks are separate and I can choose from where I'm getting my fuel. My friend did the same. There have been others who let the wing tank fill the aux tank... so you'll need to consider venting.
In either case, we both T/O and Land on the wing tank and fly straight and level on the aux tank. This helps us feel safer about there being enough head pressure to feed the engine in nose high attitudes.

Just got back from a nice long trip with NX1279 from Flabob to Independence Oregon for the TravelAir reunion. I only have 18 gallons in the center section and use about 8 gph with the O-290-3. It's doable, and in fact I'm usually ready to get out and stretch after and hour and half, but there are times when a few extra gallons would sure be nice. Had a leg that was 1 3/4 hours from Weed to Willows and when we got to Willows the airport fuel pump was busted. The nearest fuel was 15 miles away in Orlan. Made it no problem, but then took on 16 gallons. A little tighter than I'd prefer.

On the other hand, with two people and baggage, I'd sure hate to be hauling around extra fuel that I didn't need. If I were going to install extra tankage, I make sure it was seperate from the main fuel system so it could be empty when I didn't need it.

Just my $0.02

Mark

J.B...the c/g not being an issue is great news 'cause I really wanted that tank. Like Mark I'm sure I'll be ready to stretch before the extra fuel is needed but there are those times when the extra miles would be good. I thought about running it empty when not needed..that sounds right, but I'd like to flow it straight thru from top to bottom of both tanks when I am using sooo...maybe a shutoff between the tanks to separate them.

Another consideration - which was alluded to above - Most aircraft have enough fuel to outlast our backside or bladder or both, but we are not always going somewhere where fuel is available, or as mentioned above, we may be surprised that its not when we get there. The ability to carry more fuel than you'd ever fly off without stretching your legs in between can be a very handy thing.

There's a lot of time to think of things during the time it takes to build an airplane. It's very common to think of all the scenarios that might come up during the life of the plane and try to build in the provisions to deal with those scenarios. Fuel is a great example. It would be easy to dream of the time we'd want to fly the plane to Alaska, or some other cool destination. We might want to fly it some really cold winter morning. We might want to come home late in the day sometime and land after dark. The list could go on an on.

Here's my advice. Build the airplane for what you're going to do most of the time. In other words, build for the rule not the exception. If you do that, you'll have an airplane that flys really really good most of the time.

There will be times when you'll have to deal with the exception, but it's no big deal. If they're out of gas when you get there (it's happened to me) you get a ride into town and haul it back to the airplane in cans.

If it's really cold, bundle up, but don't weigh down the airplane with a massive electical system, heaters, canopies, etc.

If it's getting dark, land, drink beer, make new friends.

Airplanes that are built trying to provide for every exception always take much longer to build, they're more expensive, wind up being heavy and rarely fly as well as they're supposed to.

There's never been an airplane built that is all things to all pilots at all times. If anyone ever designs the perfect airplane, it will really mess things up by removing the excuse to have more than one airplane......

Mark

M Lightsey wrote:Build the airplane for what you're going to do most of the time.

That sounds like smart advice. I will also say, however, that extra fuel is the one mod I wish I had. I think the perfect situation would be a removable tank that could sit in the front compartment and just attach into the fuel system with a quick disconnect for those rare longer trips. Maybe with just a small transfer pump to add the fuel into the main tank when needed.

Ryan

If most of your flying is cross country traveling, then by all means incorporate extra fuel. It's what you do most of the time.

My point is simply that if most of your flying is touch and goes, or little Sunday trips to breakfast, don't run up the expense, slow the project down, and add the weight of extra fuel tanks.

Every piece of an airplane is connected to every other piece and even small changes have sometimes major consequences. For an extra few gallons of fuel you have to consider head pressure, valving, lines, quantity indication, C/G, useful load, instrument space, leg room, etc. It's no small thing, but if it make the airplane better for what you do most of time, go for it.

I've just found that guys wildly underestimate the magnitude of work required to make "small" changes, so they wind up making their lives a lot more difficult for something that they really could have lived without.

Mark

Wise words, Mark.

IMHO, the closest I've ever been to the perfect all around airplane is the RV 4. Short field, slow flight, fast and economical, aerobatic. Sort of a jack of all trades/master of none. I know, this is the Hatz forum, not an RV forum. Just wanted to agree with Mark and say one should figure out what kind of flying you want to do and then build THAT airplane.

You've talked me into it Mark. I am planning long flights so will need the peace of mind altho the 1 1/2 to 2 hr time frame rules me too. I think I'll go with a fiberglas tank under the glove box ...somewhere between 13 to 15 gals. and valve it to be able to switch from one to the other. Cruising on the little tank and taking off and landing on the wing sounds like a good practice. Another question comes to mind....if the tank is as low as it would be under the top longerons, will it have sufficient pressure to feed the engine without a pump?

You're right about where your mind goes while working ....lots of what ifs....could add tons to the plane easily, making the creature comforts. Me, myself and I have went around more than once to prevent that. And then there is the things you relegate to a time in the future after your flying.....don't know how many of those will get done once I start flying

by the by....this is Mon. Sept the 19th. Hope what happened in Reno, tragic as it was, doesn't shut it down. "they" are talking about it again.

Gaylon