I am so glad to get your reply. You are right. I think I am giving myself
a case of "analysis paralysis". Sounds like no matter what I choose,
everything will be just fine. As you know, and I should know better, most
any plane has some single point failure area that could result in
catastrophic failure. Control cables or rods are a typical example. In
those areas of all planes, including certified designs up to airliner size,
the extra safety comes from a very large design margin and not redundant
parts. That appears to be the case here. Nothing like the voice of
experience to calm paranoid nerves! Never had the courage to look directly
at a Zenair. Are they allowed to be in full view during daylight? I think
perhaps they have a great strategy to deter theft, though. I better be
quiet because I have no doubt offended someone and I do hear they are a fine
performer (but ugly in one persons opinion!).
You are right about the metal surfaces taking no more (maybe less) time than
fabric. I was surprised how much time and expense was involved when I
helped Chuck Bailey do his fabric controls. Hmm, I wonder if I went to all
metal flaperons using the Elite parts if I would have to add additional
counterweights. Right now only the separate ailerons have counterweights.
Hooking the metal flaps on to make one metal flaperon as you describe might
need more balancing. Adding at the center hinge is a great location. Tell
me more.
Thanks again,
- Chuck Skorupa -
----- Original Message -----
From: "Wayne G. O'Shea" <oifa@irishfield.on.ca>
To: "Murphy Rebel Builders List" <murphy-rebel@dcsol.com>
Sent: Wednesday, May 10, 2000 4:07 PM
Subject: Re: ps to my previous
someChuck, I think you are getting a little "over worried" about the aileron
hinges breaking. Haven't seen a damaged hinge bracket yet and I've seen
radius,pretty mangled wings! Even a wing that was curved to about a 20 foot
nicelywith outboard flaperon to match, had perfect hinge brackets!!!
I have metal flaperons on my Rebel (.016 thickness, same as SR2500),
themoverlapped in the center to make one large surface and I wouldn't trade
hingefor the world.(although I do find the fabric covered Rebel lighter on the
controls!!!) That 8 pound weight hanging from each set, at the center
thebracket, that I keep knocking myself out on is another story!!!!! The
aluminum covering took the same time (within minutes) of fabric covering
Xflaperons, to the Polyspray stage, on others I have done. Uses one full 4
out12 sheet, cut in 1' x 6' pieces.
If you are having trouble sleeping at night over this problem, just pull
supports:a Zenair information package to read and it will put you to sleep!!!!
Blue skies,
Wayne G. O'Shea
www.irishfield.on.ca
-----Original Message-----
From: Charles Skorupa <Chas@wa.freei.net>
To: Murphy Rebel Builders List <murphy-rebel@dcsol.com>
Date: Wednesday, May 10, 2000 6:44 PM
Subject: Re: ps to my previous
Great info, Geert. If I go to metal flaps, the flaps will have 3
Iofone at each end and one in the middle of each flap. But the outboard endsupporteach flap will still be sharing the support bracket with the inboardthefor 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 visitingfactory, 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%???
oncounterweight.can't remember??). At the least, I should add that amount ofIf I split the flaps and use fabric ailerons, no need for counterweights
goingthe aileron or the metal flaps. To reiterate, my primary reason for
surfacescouldto metal flaps is to get some level of redundant support, although onetheargue that if the outboard aileron bracket failed, I would be faced withsame potential problem since the fabric aileron has only 2 supports.
Basically, I hate the weight penalty associated with metal control
bracketstoand especially the counterweight. I feel really stupid radiusing every
0.020 bracket, shaving all edge distances, adding 1 inch lightening holessensitive,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,but least redundant, design appears to be the original Rebel fabric
flaperons. The next best is split metal flaps with 3 flap support
theand fabric ailerons. The best for strength, safety, and longevity and
andworst for weight and sensitive control is the separate all metal flaps
theailerons having 3 supports each and a counterweight like the Elite and
toSuper 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
cracksaffix 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
withaddressedat 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
PS I reread Charles Skorupa's question and I realized I had notflapsit. Here is my very humble opinion: go very careful here, mixing metalmayand fabric ailerons, unless there is no large difference in weight thisput some crazy stress on that center hinge. This time I would stick
don'tthefactory's opinion, if you can get them to give you one! After all I
alleitherthink they ran that mix themselves or did they? My gutfeeling says,go all metal (AND BALANCE THE SURFACES) both ailerons and flaps or go
*---------------------------------------------------------------------------*--------------------------------------------------------------------------fabric. Ok? Geert
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