In a message dated 11/27/01 10:15:14 AM, [EMAIL PROTECTED] writes:
One other thing to be careful of is the difference between stiffness and
stiffness-to-weight. The stiffness of most carbon fiber-epoxy per square
inch of material is nowhere near as high as that of steel. A 1/8 diameter
Mark Drela wrote:
Someone else mentioned using hardened RDS torsion rods.
This is not a solution, since hardening has little or
no effect on the stiffness of a metal. It only increases
its strength.
Mark. . .As the maker of the hardened and tempered drive shafts for the
RDS, I'm
At 11:59 PM 11/18/2001 -0500, Mark Drela wrote:
Someone else mentioned using hardened RDS torsion rods.
This is not a solution, since hardening has little or
no effect on the stiffness of a metal. It only increases
its strength.
Should work just fine. In this case I think one is designing to
Harley,
EXQUISITE!
At first a good idea is ridiculed and maligned by those who don't
understand it, slowly it is accepted, so much so that finally it is
embraced as their own! Author unknown.
Give them MORE time.
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This did stiffen the surfaces to an acceptible level,
but there was still some flex right where the rod bends
45 or 90 degrees. An all carbon rod would be ideal!
Uh.. actually, a carbon rod would be horrible. Unidirectional
carbon has a puny shear modulus compared to steel, even aluminum.
I have tried RDS in F3B ships with good results. There are however a
few problems. F3B control surfaces must be very ridid (remember Daryl
P. recent post describing why he likes using 3 control surfaces per wing
panel with 3 servos per wing panel for added control rigidity). The RDS
system uses
A hollow-molded wing is likely to have less trouble in this regard.
However, even with these, any time you start adding or subtracting stuff
that is going to possibly alter the load paths in a highly-loaded
structure, it's best to proceed with caution!
It is kind of nice to build RDS
of religious dogma with
little empirical data to demonstrate claims.
Let me see a before-and-after set of numbers to evaluate.
--Bill
From: Harley Michaelis [EMAIL PROTECTED]
To: Bob Pope [EMAIL PROTECTED], Bill Harris
[EMAIL PROTECTED]
CC: [EMAIL PROTECTED]
Subject: [RCSE] RDS drag reduction
: [EMAIL PROTECTED]
Subject: [RCSE] RDS drag reduction, speed increase.
Date: Fri, 16 Nov 2001 16:52:20 -0800
Just thinking, if 5% reduced drag could increase speed that much, a
16
second run would be reduced to 15.2 seconds. If drag is reduced 12% as
Bob
says, it would be reduced to 14.08 seconds
Bill Harris wrote:
Give us empirical data to show that RDS gives % reduction in drag, and
this x-% reduction in drag correlates to a y-% increase in
performance-- speed, sink rate, whatever.
I have nothing against the RDS system, and it seems to be a
wonderful idea, but these
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