Inboard Tanks...

[Bootlegger]

 
    Mornin" from South Louisiana,
  Fellows I see a lot of tanks on Ringmaster's mounted inboard, other than the short nose, is there another advantage ??
   "Of all the things I've lost, I miss my mind the most"...

[Joe Messinger]

I can't say that I know of any advantages other than extra room for mounting tanks inboard on Ringmasters.  I have found that, for me, a clunk set up works better than tanks with rigid plumbing.

Joe

[Bob Reeves]

Only benefit is more room for the tank, so far I haven't found a down side. Not sure how one would do it with a metal tank.. Would need to be flat on the pickup side, then where would you put the pickup tube.. Works great with plastic clunk tanks.

[john e. holliday]

Sitting here looking at my Ring Master, why would you need more than 3 to 3.5 ounces of fuel with a 25 size engine.  The tank on my ARF Flite Streak is between the engine and wing.  Just measured the distance and it is 4 inches between leading edge and back of the Fox 35 Stunt.  DOC Holliday

[Alan Hahn]

There is one positive reason to have an inboard tank. If the plane begins to wind up, the pressure head is positive and will richen the mixture. This is opposite to a uniflow tank being on the outboard fuse side where the mixture will lean. If the tank is conventionally plumbed, the mixture will still be richer with the inboard tank than with the outboard tank.

[Kim Mortimore]

My understanding is that inboard tanks were first used about 35 years ago on slow combat planes with nose moments somewhere between that of a fast combat plane and a R'master or Streak. 

Basic physics would seem to predict that the mixture would go rich after launch as centrifugal force begins pushing the fuel away from the center of the circle, and thus toward the engine, but several guys in the Alameda, CA club have inboard mounted Hayes brand clunk tanks on OS 20FP powered ARF Streaks that purr like kittens.

Kim Mortimore

[Alan Hahn]

Kim,
In general they probably do go richer after takeoff - at least my uniflow outboard tanks typically go leaner. As always it depends--when the plane is sitting on the ground, the reference pressure point isn't always obvious to me. In any case, I normally compensate by setting the ground setting richer (for outboard tanks) so I assume the inboard tank guys set their on-ground mixture a little on the leaner side.

[Alan Hahn]

I note this is one of those "double-posts"  . I was reading the thread over on SSW and was surprised when I couldn't find my original comment. FInally dawned on me that I had made my comment here .

[Bradley Walker]

There is one positive reason to have an inboard tank. If the plane begins to wind up, the pressure head is positive and will richen the mixture. This is opposite to a uniflow tank being on the outboard fuse side where the mixture will lean. If the tank is conventionally plumbed, the mixture will still be richer with the inboard tank than with the outboard tank.

Kee-rect.

That Yatsenkos use this feature on the RTF models.  The Europenas have been doing this for years.  Kaz Minato oftne spoke of inboard shimming necessary for controlling windup.

I know all of my new designs will have slightly inboard tank pickup center lines.

Most all profiles are set up to go the wrong direction when they wind up.  The fuel head increases with an outboard tank.  Some engines wind up worse, some just run like crap (most Foxes are credited as running worse ouboard, especially with uniflow---which increases to need for even more suction).