one at each end and one in the middle of each flap. But the outboard end of
each flap will still be sharing the support bracket with the inboard support
for the aileron. I think that there is probably no way I can get away
without adding a counterbalance weight if I use metal flaps and fabric
ailerons and hook them together as flaperons. As I recall when visiting the
factory, when they determined how much counterweight to use they took a
metal aileron and then added enough weight to achieve a neutral balance.
They then removed a certain per cent of the counterbalance weight (20%??? I
can't remember??). At the least, I should add that amount of counterweight.
If I split the flaps and use fabric ailerons, no need for counterweights on
the aileron or the metal flaps. To reiterate, my primary reason for going
to metal flaps is to get some level of redundant support, although one could
argue that if the outboard aileron bracket failed, I would be faced with the
same potential problem since the fabric aileron has only 2 supports.
Basically, I hate the weight penalty associated with metal control surfaces
and especially the counterweight. I feel really stupid radiusing every
0.020 bracket, shaving all edge distances, adding 1 inch lightening holes to
save a zillionth of an ounce, only to add 5 lbs of counterweight dead
ballast! I keep coming back to the fact that the most efficient, sensitive,
but least redundant, design appears to be the original Rebel fabric
flaperons. The next best is split metal flaps with 3 flap support brackets
and fabric ailerons. The best for strength, safety, and longevity and the
worst for weight and sensitive control is the separate all metal flaps and
ailerons having 3 supports each and a counterweight like the Elite and the
Super Rebel use.
I have played with a design that uses double brackets at each hanger of
higher strength material to get redundancy. Another possible remedy is to
affix some sort of safety cable at each support bracket so if the bracket
parted company, the failure would not be catastrophic. There is just
something about the potential of a crack in that double-loaded, center
common flap/aileron bracket that seems like it could ruin your whole day.
At the very least, I would be thoroughly checking those brackets for cracks
at every preflight and more extensively during each annual. Can someone
save me from my paranoia?
- Chuck Skorupa -
----- Original Message -----
From: "Geert Frank" <storchpilot@mediaone.net>
To: "murphy archives" <murphy-rebel@dcsol.com>
Sent: Wednesday, May 10, 2000 2:27 PM
Subject: ps to my previous
flapsPS I reread Charles Skorupa's question and I realized I had not addressed
it. Here is my very humble opinion: go very careful here, mixing metal
mayand fabric ailerons, unless there is no large difference in weight this
theput some crazy stress on that center hinge. This time I would stick with
*---------------------------------------------------------------------------factory's opinion, if you can get them to give you one! After all I don't
think they ran that mix themselves or did they? My gutfeeling says, either
go all metal (AND BALANCE THE SURFACES) both ailerons and flaps or go all
fabric. Ok? Geert
--------*
*---------------------------------------------------------------------------The Murphy Rebel Builders List is for the discussion
between builders and owners of Murphy Rebel aircraft.
Archives located at:
http://www.dcsol.com/murphy-rebel/lists/default.htm
--------*
*-----------------------------------------------------------------------------------*
The Murphy Rebel Builders List is for the discussion
between builders and owners of Murphy Rebel aircraft.
Archives located at:
http://www.dcsol.com/murphy-rebel/lists/default.htm
*-----------------------------------------------------------------------------------*
-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------
