NCIS

Hey,

I'm building a TF 1/8 scale F4U-1A Corsair and am going all out scale. To do so I have two things I need cleared up. I put my hatch to get to things like the switches, air fill, remote glow ignitor, fuel fill, and air pressure gauge so they wouldn't be seen. My 2 questions are.

1.) The tank is up front where it belongs but the fuel fill is in the hatch area. Will getting fuel from the fill valve to the carb be a problem? I know I can fill the tank OK.

2.) I have a custom exhaust from Keleo Creation's and was wondering what to do about the back pressure issue for my Magnum 120 4-stroke. What should I do? There isn't any nipple and it's all straight piping without a muffler.

Here is the hatch and then it's location on the plane.

Gibbs

KitBuilder

Not sure about you muffler question.. but also not sure what your asking in number 1? If you can fill the tank from the remote line... what would that have to do with getting fuel to the carb if close to the motor?
Mike

Crash Campbell

Hi NCIS,

The critical thing is the height of the tank. Providing the centre of the tank is approx level with the spray bar on the carby or the housing if using a remote needle valve the friction loss in the line should be of little detriment. You could always go with larger diameter tubing if this is a worry for you.

Four stroke motors don't need a pressure line from the muffler and run fine without one, unlike two strokes.

If I were you I would set it all up and test. I really don't think you will need larger diameter fuel tubing, tank fittings and fuel valve. If the tank is way high or low a pump cures most ills.

Cheers,

Colin

bluestratos

I believe if you are planning to put a filler valve in that redirects the fuel flow while filling, the line will be way too long if you put it all the way back there. Also you will add significant wieght to run the line all the way back then all the way forward again and if the line ever fails you will likely get fuel inside your fuselage. I put the filler valve inside the cowl and use the stock filler probe soldered to brass tube extension. If you are using a fake radial engine, just locate the filler so that you can reach through portion of the cowl where you cut the air cooling portion away. I have done this on a lot of planes and it works great. I usually make a custom alum bracket that I mount the fill valve to then mount that to the fire wall or engine mount.. what ever works best.

Hope this makes sense,
Randy

bla bla

If you're going all out scale...in other words comitting a GREAT deal of time to this project, the last thing you need is a fuel filler valve and the complex set-up!
Notoriously trouble some, you'll be chasing engine problems more than you be flying.

If you look at 99% of all super-pro' F4C competitor models you'll notice two things. Nr. 1: On the outside they look highly detailed and complex.
And beause of this... Nr.2 : the insides are completely basic... almost niave in there approach.

Scale models are complex enough all ready... use a simple pipe/fuel tube and blocker thats tucked inside the cowl. Then fingered out for filling!
Complex setups ... they're for Hanger Queens and hobbyshop victims.

jaka

Hi!
Bla Bla is right !
Always try to Follow the KISS principle! Never ever use any fuel valves or gadgets of any kind !!! Keep it simple and avoid weight as the plaque and learn how to fly! Competing in pylonracing, aircombat or aerobatics is good way of upholding flying ability and keeping that valuble aircraft of yours.

Charlie P.

If they don't have a pump they do. I believe the Magnums all require muffler taps or seperate pumps (like a Perry).

Getting the fuel to the tank will be easy. You could run six feet of hose if necessary. But, you'll still have to remove the carb line or clamp it off to prevent flooding when filling.

mscic-RCU

My Feedback: (6)

why not use a fuel dot and a 3rd fill line.

Charlie P.

That would be as I described, but you still have to prevent the full tank (or fuel in the engine line) from flooding the carb when you fuel up.

alpinestar

I used a fuel dot/3rd line on the same model; if you keep the fuel filling rate reasonable (slow) and close the throttle before filling, it is a very workable situation. Done this on at least a dozen planes. keep it simple! I put mine right on top of the fuselage in front of the canopy. (is this the full-scale fill location?) My switches and air filler are hidden behind a hatch (where the fuel cannot enter them!)

If the keleo exhaust is steel, you could try to braze a nipple for pressure without tremendous fear of burning through but be careful nonetheless. I have brazed a 1/8th brass tube to 5/16" brass tube for homemade exhausts before; often requiring multiple attempts but it does work. Put it as close as reasonable to the engine for the best chance at getting some pressure out of it.

Good luck! yet to fly mine; Saito 125; glass finish, sierra retracts, single servo flaps, cockpit kit, functional landing gear doors. 10 lbs dry!
Pics & details are somewhere on Corsairjock's "1/8 corsair mods" thread. Lots of great info there.