Design > Stunt design
Ted's Tucker Special Ballast Experiment
Kim Mortimore:
A question occurred to me in relation to Ted's famous (and very interesting to me) experiment. If it were possible to produce a scaled-up 60-size version of Ted's Tucker in which all else is identical: balsa density, number of dope coats, proportionally higher engine weight, etc. is it likely that the same need for extra weight would occur?
In other words, would the larger control surfaces require sufficiently greater control force so that additional weight might be required, OR, would the greater absolute mass of the larger plane without ballast alone be sufficient to eliminate the problem? Thanks in advance for replies.
Brett Buck:
--- Quote from: Kim Mortimore on September 28, 2013, 01:25:18 PM ---A question occurred to me in relation to Ted's famous (and very interesting to me) experiment. If it were possible to produce a scaled-up 60-size version of Ted's Tucker in which all else was identical: balsa density, number of dope coats, proportionally higher engine weight, etc. is it likely that the same need for extra weight would occur?
In other words, would the larger control surfaces require sufficiently greater control force that additional weight might be required, OR, would the greater absolute mass of the larger plane without ballast alone be sufficient to eliminate the problem? Thanks in advance for replies.
--- End quote ---
Maybe not, because as you scale something, the area goes up as the square of the linear dimensions, and the weight goes up as the cube of the dimensions.
I'd have to think about it. I have seen a few somewhat larger airplanes that suffered greatly from being built too light and too powerful which made the trimming beyond the capabilities of the pilot to diagnose and correct.
Brett
Jim Kraft:
I am far from an expert in this kind of thing, but I think there is an optimum weight for every plane. I have an old Nobler that was given to me that weighs 52 ounces and is the best cornering plane I have ever flown. It turns extremely tight corners with no bounce and comes out right on line. Even with the Fox 35 that's in it.
Phil Krankowski:
When you increase the size of an airframe, unless you are building with solid wood, the final density of the skinned and finished airplane will be lower than a smaller ship. This is a large function of built up construction containing mostly air volume.
A large plane that is too light may benefit from ballast at the CG...although how much in CL? I know RC gliders, particularly slope gliders, will benefit from ballast under windy conditions.
The general rule of lighter is better probably still holds.
Phil
Gerald Arana:
--- Quote from: Jim Kraft on September 28, 2013, 05:38:54 PM ---I am far from an expert in this kind of thing, but I think there is an optimum weight for every plane. I have an old Nobler that was given to me that weighs 52 ounces and is the best cornering plane I have ever flown. It turns extremely tight corners with no bounce and comes out right on line. Even with the Fox 35 that's in it.
--- End quote ---
BINGO! That is exactly what I was trying to express in the other (DELETED) thread. y1
Brett, Not being an AE I like that squared & cubed thing.... I have experienced it in my past (Glider Competitons) The bigger ships fly better for that application.
Will we see you in Napa on the 6th?
Cheers, Jerry
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