Design > Stunt design

Odd question on a profile model: Keep the inboard side without protuberances?

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Bill Schluckbier:
Hello,

I have another odd question.  Now that I am back flying C/L all of my models are electric.  To keep the look of the models tidy when viewed from outside the circle I place the battery, ESC and timer on the inboard side.  In terms of retention I think that it is a good idea for the battery to be on the inboard side, it is partially recessed into the fuselage and the centripetal force helps hold it in place.

At any rate, having all of those protuberances disrupts the airflow on that side of the fuselage; I am just wondering if model would fly better  if it were clean.  As the airplane flies around in a circle that is the side of the fuselage which first encounters the incoming air. On the outboard side I would expect the airflow to be more turbulent and hence less affected by having the battery et. all. hanging on that side.

Any thoughts?

Bill

Ken Culbertson:

--- Quote from: Bill Schluckbier on December 27, 2023, 04:14:47 PM ---Hello,

I have another odd question.  Now that I am back flying C/L all of my models are electric.  To keep the look of the models tidy when viewed from outside the circle I place the battery, ESC and timer on the inboard side.  In terms of retention I think that it is a good idea for the battery to be on the inboard side, it is partially recessed into the fuselage and the centripetal force helps hold it in place.

At any rate, having all of those protuberances disrupts the airflow on that side of the fuselage; I am just wondering if model would fly better  if it were clean.  As the airplane flies around in a circle that is the side of the fuselage which first encounters the incoming air. On the outboard side I would expect the airflow to be more turbulent and hence less affected by having the battery et. all. hanging on that side.

Any thoughts?

Bill

--- End quote ---
I don't think it makes a whole lot of difference on a profile.  They are really drag buckets with all of the things that have to be exposed.  Making them presentable is a good idea.  Neat wiring, etc.  I do a similar thing on mine.  I use soft thick doublers around the nose to let me blend into a spinner.  I make a rather large battery cutout through both sides and put a 1/16" plywood divider in the center.  I mount the ESC on the inboard side, the battery on the outboard side and the timer in a tunnel on the inboard side.  The tunnel hides all those ugly wires under a hatch.  Everything is exposed but it is orderly.

The reasons I put the battery on the outside is balance.  With it on the inboard you need more tip weight.  On my contest profile I have tunnels covered by hatches all over the nose for hiding various wires, the timer, the telemetry port and for cooling.  None of the wiring is exposed except where it connects to the ESC.  If you are worried about spectators/judges looking at the nose as it goes by add some trim to distract them. LL~

Ken

Bill Schluckbier:
Hello Ken,

Thank you for your reply.  I agree that profiles will be draggier than full fuselage models; in this case I was wondering if it had an effect on the "lift" that the fuselage might generate when the model is up high on the circle.  I have a modified Oriental with reasonably significant side area that seems to fly fairly well; even when it starts to get a little windy (say 10-15 mph).  It is a small and reasonably light model so you would expect it to be more affected by the wind.  At any rate, I was wondering if the side area would be more effective had the stuff been mounted on the other side.

Thanks,

Bill

Ken Culbertson:

--- Quote from: Bill Schluckbier on December 28, 2023, 09:34:42 AM ---Hello Ken,

Thank you for your reply.  I agree that profiles will be draggier than full fuselage models; in this case I was wondering if it had an effect on the "lift" that the fuselage might generate when the model is up high on the circle.  I have a modified Oriental with reasonably significant side area that seems to fly fairly well; even when it starts to get a little windy (say 10-15 mph).  It is a small and reasonably light model so you would expect it to be more affected by the wind.  At any rate, I was wondering if the side area would be more effective had the stuff been mounted on the other side.

Thanks,

Bill

--- End quote ---
That is a good question.  I may be off here but I have found the best cure for overhead line tension is momentum and as much tip weight as you can carry without hinging.  I have a really dirty inboard side on the one in the pix but gobs of side area.  It has an active timer so I get a huge boost when I am upstairs.  I don't think the lift produced by the fuselage amounts to much.  Even with an airfoiled shape, which I have tried, the prop vortex seems to kill it. 

Ken

Howard Rush:
I wouldn’t expect much aerodynamic difference between having stuff on one side of the fuselage vs. the other, but the mass distribution may matter. I suspect the airplane would trim out with leadouts farther aft for the case with stuff on the side toward the center of the circle. I hope to calculate something, but it’s a race with dementia.

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