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General control line discussion => Open Forum => Topic started by: Bootlegger on April 30, 2007, 08:17:25 AM

Title: Inboard Tanks...
Post by: Bootlegger on April 30, 2007, 08:17:25 AM
 
    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"... #^
Title: Re: Inboard Tanks...
Post by: Joe Messinger on April 30, 2007, 08:28:41 AM
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
Title: Re: Inboard Tanks...
Post by: Bob Reeves on April 30, 2007, 10:32:12 AM
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.
Title: Re: Inboard Tanks...
Post by: john e. holliday on May 01, 2007, 11:58:27 AM
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
Title: Re: Inboard Tanks...
Post by: Alan Hahn on May 01, 2007, 12:55:42 PM
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.
Title: Re: Inboard Tanks...
Post by: Kim Mortimore on May 01, 2007, 01:19:22 PM

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
Title: Re: Inboard Tanks...
Post by: Alan Hahn on May 01, 2007, 03:11:04 PM
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.
Title: Re: Inboard Tanks...
Post by: Alan Hahn on May 01, 2007, 03:13:05 PM
I note this is one of those "double-posts"  n1. 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 n~ .
Title: Re: Inboard Tanks...
Post by: Bradley Walker on May 06, 2007, 07:06:03 PM
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).