[SPAM] Re: [SPAM] Re: [SPAM] Re: [SPAM] Re: Rudder counterbalance ?
Ed Alt
ed_alt at hotmail.com
Sun May 1 16:54:11 AKDT 2005
Eric:
Turned out to be 2.2 oz. Not as heavy as I thought.
----- Original Message -----
From: "Ed Alt" <ed_alt at hotmail.com>
To: <discussion at nsrca.org>
Sent: Saturday, April 30, 2005 9:50 PM
Subject: [SPAM] Re: [SPAM] Re: [SPAM] Re: Rudder counterbalance ?
> Eric, I haven't weighed it yet, will try tomorrow if my friend reads his
> email and remembers to bring it to the field.
>
> ----- Original Message -----
> From: "Grow Pattern" <pattern4u at comcast.net>
> To: <discussion at nsrca.org>
> Sent: Saturday, April 30, 2005 5:12 PM
> Subject: Re: [SPAM] Re: [SPAM] Re: Rudder counterbalance ?
>
>
>> Ed,
>> The bounce is coming from the springy tension in the wires. The
>> rudder can be moved before the servo arm moves. Troy told me that he and
>> TF use 2 strand CL wire to stop the "spring/stretch" effect on their
>> rudders.
>>
>> I figure if I can get to do it on the bench, then don't fly it like that.
>> If yours does not do it with the rudder hanging free, i.e. the tail-wheel
>> is off the ground, then you could be OK. Did you weigh the OTOP rudder?
>>
>> Eric.
>>
>>
>> ----- Original Message -----
>> From: "Ed Alt" <ed_alt at hotmail.com>
>> To: <discussion at nsrca.org>
>> Sent: Saturday, April 30, 2005 5:24 AM
>> Subject: [SPAM] Re: [SPAM] Re: Rudder counterbalance ?
>>
>>
>>> meant to say stored energy in the flexed hinges, not 'fixed' hinges
>>>
>>> ----- Original Message -----
>>> From: "Ed Alt" <ed_alt at hotmail.com>
>>> To: <discussion at nsrca.org>
>>> Sent: Saturday, April 30, 2005 5:21 AM
>>> Subject: [SPAM] Re: Rudder counterbalance ?
>>>
>>>
>>>> Eric
>>>> Just curious about more details on the hinging on the Impact. Having
>>>> just completed an OTOP, I wonder if the Impact has a similar
>>>> arrangement. If I would have gone with the stock setup, it would have
>>>> meant that 4 small Robart hines would be hanging suspended in air over
>>>> 1/4" either side of the hinge line. This seemed unacceptable, as I
>>>> figured it would just break the hinges in short order from all the
>>>> flexing of the unsupported plastic. All I did was to add balsa filler
>>>> blocks for each hinge location. It required cutting off the nub on the
>>>> bottom of the rudder to let me slide the blocks in, but that was easy
>>>> to do and reset the piece later. Rock solid so far (7 flights) with an
>>>> 8411 converted to SA and this rudder is realtively heavy as well. I
>>>> don't have the weight figure, but can get it from a friends unfinished
>>>> OTOP if it helps to unravel the mystery.
>>>>
>>>> I guess the point of asking about this is that there may be a combined
>>>> effect of the relatively high mass of the ruuder and the flex of the
>>>> hinges if something similar was in play with your original setup. I
>>>> understand the way the oscillations could start/sustain with just too
>>>> much mass for the setup to contend with. However any flex could make
>>>> it even easier to commence, as the servo's attempt to arrest rudder
>>>> movement would be hampered and secondary movements from the stored
>>>> energy in the fixed hinges would have to be dealt with milliseconds
>>>> later.
>>>>
>>>> Ed
>>>>
>>>> ----- Original Message -----
>>>> From: "Grow Pattern" <pattern4u at comcast.net>
>>>> To: <discussion at nsrca.org>
>>>> Sent: Saturday, April 30, 2005 12:43 AM
>>>> Subject: Re: Rudder counterbalance ?
>>>>
>>>>
>>>>> Jim,
>>>>> I had already converted the IMPACT supplied rudder over to a
>>>>> regular Mylar hinge set up because of the side-play in the hinge-pin
>>>>> design supplied.
>>>>>
>>>>> It oscillated with the stick pin hinges at the first switch-on. I
>>>>> "pulled" the composite the rudder off and fitted it with a new
>>>>> stern-post and beveled the LE, on the rudder. Then I tried all of the
>>>>> servos previously listed.
>>>>>
>>>>> I then cut off the IMPACT rudder and fitted the new (red) one as you
>>>>> can see on RCU.
>>>>>
>>>>> As powerful as our new digital servos are I don't think that they
>>>>> "brake" the return swing as well as they initiate the first
>>>>> movement/response.
>>>>>
>>>>> It is noticeable that the bigger planes use multiple servos with the
>>>>> thinking that more power is needed. It is more stopping power that,
>>>>> IMHO, the we really need.
>>>>>
>>>>> I had an 8611 that bounced when used to drive a big old VISION rudder.
>>>>> After fitting a damper from an RC car it performs flawlessly.
>>>>>
>>>>> Regards,
>>>>>
>>>>> Eric.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> ----- Original Message -----
>>>>> From: "J.Oddino" <joddino at socal.rr.com>
>>>>> To: <discussion at nsrca.org>
>>>>> Sent: Friday, April 29, 2005 3:26 PM
>>>>> Subject: Re: Rudder counterbalance ?
>>>>>
>>>>>
>>>>>> Eric,
>>>>>> What you were experiencing was oscillation of a servomechanism and
>>>>>> that
>>>>>> could contribute to flutter and flutter could be what is breaking the
>>>>>> Impacts but I've never heard anyone say they heard the rudder flutter
>>>>>> before
>>>>>> the fuse exploded. I don't think we understand the root cause yet.
>>>>>> Right now I'm interested in the servo/rudder oscillation. I'm
>>>>>> wondering if
>>>>>> the real solution is completely due to the light weight rudder or/and
>>>>>> to an
>>>>>> improved hinging system, or did both have the same hinge
>>>>>> installation? Can
>>>>>> you hang weight on your present rudder and make it oscillate? It
>>>>>> sure would
>>>>>> be nice to cure this problem for all time because I've seen it on
>>>>>> many
>>>>>> planes. I've never heard of it breaking fuselages before though.
>>>>>> Thanks for all of your experimentation. In the end it is more
>>>>>> important
>>>>>> than understanding the theory.
>>>>>> Jim O
>>>>>> ----- Original Message -----
>>>>>> From: "Grow Pattern" <pattern4u at comcast.net>
>>>>>> To: <discussion at nsrca.org>
>>>>>> Sent: Thursday, April 28, 2005 8:55 PM
>>>>>> Subject: Re: Rudder counterbalance ?
>>>>>>
>>>>>>
>>>>>>> Peter,
>>>>>>> I nearly got to go to bed.! ...Just ran
>>>>>>> downstairs...Tripped
>>>>>>> over #2 Son who is back from carrier duty - he said we dropped a lot
>>>>>>> of
>>>>>>> "stuff " out there. Planes all came back without ordnance,! No lost
>>>>>>> planes....A bit worried about the local girls however.. it must be
>>>>>>> that
>>>>>>> uniform thing :-)
>>>>>>>
>>>>>>> Where was I?...Both supplied IMPACT rudders weigh 3.1 oz each
>>>>>>> without
>>>>>> hinges
>>>>>>> or horns
>>>>>>>
>>>>>>> Replacement rudders weigh 1.3 oz before covering.
>>>>>>>
>>>>>>> I tried the supplied rudder and five different servos including an
>>>>>>> 8611
>>>>>> and
>>>>>>> they all bounced back and forth badly and were potentially
>>>>>>> destructively.
>>>>>>>
>>>>>>> I then cut it off (the old rudder) and fitted a foam balsa
>>>>>>> replacement.
>>>>>>> Tests showed no bounce with any of the servos. [8611, 8411, 8417,
>>>>>>> 8417
>>>>>> with
>>>>>>> 8411 gears and the heli 8311 (nylon gears except for output shaft.]
>>>>>>>
>>>>>>> I did managed to stop the bounce another way. I also tried using a
>>>>>>> single
>>>>>>> wire as opposed to multi-strand. It did work but once in a while I
>>>>>>> saw bad
>>>>>>> "hunting" as it located the center.
>>>>>>>
>>>>>>> These Impacts have polyurethane foam liners about 1.5-mm thick with
>>>>>>> a skin
>>>>>>> of glass inside that. They are pretty stiff to begin with.
>>>>>>>
>>>>>>> I did notice that a vertical former at the rear of the canopy area
>>>>>>> made a
>>>>>>> huge difference in stiffness. Also switching to a four bolt wing
>>>>>>> retention
>>>>>>> system made the center more rigid.
>>>>>>>
>>>>>>> I have abused my IMPACT #1 and hope that all the mods keep doing
>>>>>>> their
>>>>>> job.
>>>>>>> I still think that the rudder is simply just too heavy and the
>>>>>>> spring/stretch in the pull-pull wire combines to oscillate the
>>>>>>> rudder just
>>>>>>> like PIO.
>>>>>>>
>>>>>>> Regards,
>>>>>>>
>>>>>>> Eric.
>>>>>>>
>>>>>>> ----- Original Message -----
>>>>>>> From: "Peter Pennisi" <pentagon.systems at bigpond.com>
>>>>>>> To: <discussion at nsrca.org>
>>>>>>> Sent: Thursday, April 28, 2005 6:19 PM
>>>>>>> Subject: RE: Rudder counterbalance ?
>>>>>>>
>>>>>>>
>>>>>>> >
>>>>>>> > I am aware of the braces and internal formers. There have been
>>>>>>> > recent
>>>>>>> > cases
>>>>>>> > of failures with all the supporting structures in place.
>>>>>>> >
>>>>>>> >
>>>>>>> > Eric,
>>>>>>> >
>>>>>>> > How much do your new rudders weigh typically?
>>>>>>> >
>>>>>>> >
>>>>>>> > Regards,
>>>>>>> >
>>>>>>> >
>>>>>>> > Peter
>>>>>>> >
>>>>>>> >
>>>>>>> > Peter Pennisi
>>>>>>> > Pentagon Systems QLD Pty Ltd
>>>>>>> > P.O Box 4280
>>>>>>> > Eight Mile Plains
>>>>>>> > QLD 4113
>>>>>>> > Australia
>>>>>>> > Phone: 61+0738414234
>>>>>>> > Fax: 61+0738414264
>>>>>>> > Mobile: 0408007206
>>>>>>> > Email: pentagon.systems at bigpond.com
>>>>>>> >
>>>>>>> > -----Original Message-----
>>>>>>> > From: discussion-request at nsrca.org
>>>>>>> > [mailto:discussion-request at nsrca.org]
>>>>>>> > On
>>>>>>> > Behalf Of Atwood, Mark
>>>>>>> > Sent: Friday, 29 April 2005 4:56 AM
>>>>>>> > To: discussion at nsrca.org
>>>>>>> > Subject: RE: Rudder counterbalance ?
>>>>>>> >
>>>>>>> > Well...I can certainly speak to needing this in the Rev
>>>>>>> > Pro...which I'm
>>>>>>> > guessing isn't a whole lot different than the Impact in
>>>>>>> > construction.
>>>>>>> > The fuselage buckled and snapped in half in flight (and yes...it
>>>>>>> > still
>>>>>>> > managed to fly to the ground with relatively little damage).
>>>>>>> > Added the
>>>>>>> > light (4gm) "Ladder" crutch plate behind the wing and no problems
>>>>>>> > at
>>>>>>> > all.
>>>>>>> >
>>>>>>> > I have a photo of the brace if someone is interested...contact me
>>>>>>> > offline.
>>>>>>> >
>>>>>>> > -Mark
>>>>>>> >
>>>>>>> > -----Original Message-----
>>>>>>> > From: discussion-request at nsrca.org
>>>>>>> > [mailto:discussion-request at nsrca.org]
>>>>>>> > On Behalf Of Wayne Galligan
>>>>>>> > Sent: Thursday, April 28, 2005 2:26 PM
>>>>>>> > To: discussion at nsrca.org
>>>>>>> > Subject: Re: Rudder counterbalance ?
>>>>>>> >
>>>>>>> > I have had conversations with a few people that own these
>>>>>>> > airframes
>>>>>>> > (Impact)and they along with a few others have strengthened the
>>>>>>> > fuse in
>>>>>>> > two
>>>>>>> > ways. A ladder type frame in the fuse from the wing t.e back to
>>>>>>> > the
>>>>>>> > stab
>>>>>>> > area and another put a stiffener(former) at the front of the wing
>>>>>>> > area
>>>>>>> > to
>>>>>>> > decrease the possibility of compression of the fuse in this area.
>>>>>>> > It is
>>>>>>> > believed that compression of the fuse in this area contributes to
>>>>>>> > a wave
>>>>>>> > progression all the way back to the tail section. The tail
>>>>>>> > section
>>>>>>> > being
>>>>>>> > the smallest and weakest area gets whipped and eventually the fuse
>>>>>>> > breaks or
>>>>>>> > contributes to tail feather flutters.
>>>>>>> >
>>>>>>> > From what I've heard.... FWIW
>>>>>>> >
>>>>>>> > WG
>>>>>>> >
>>>>>>> >
>>>>>>> > ----- Original Message -----
>>>>>>> > From: "Peter Pennisi" <pentagon.systems at bigpond.com>
>>>>>>> > To: <discussion at nsrca.org>
>>>>>>> > Sent: Thursday, April 28, 2005 4:29 AM
>>>>>>> > Subject: Rudder counterbalance ?
>>>>>>> >
>>>>>>> >
>>>>>>> >>
>>>>>>> >>
>>>>>>> >> Hi all,
>>>>>>> >>
>>>>>>> >>
>>>>>>> >> Most of you would be aware that a number of Composite ARF
>>>>>>> >> "IMPACT"
>>>>>>> > have
>>>>>>> >> failed from suspected rudder flutter.
>>>>>>> >>
>>>>>>> >>
>>>>>>> >> I raise a couple of questions to this forum;
>>>>>>> >>
>>>>>>> >>
>>>>>>> >> I know that the purposes of counterbalances are to reduce the
>>>>>>> >> loads on
>>>>>>> >> servos and linkages in our application but what are the side
>>>>>>> >> effects.
>>>>>>> >>
>>>>>>> >> Can a rudder counterbalance create undesired torsional stresses
>>>>>>> >> on the
>>>>>>> >> fuselage?
>>>>>>> >>
>>>>>>> >> Can a poorly configured and tensioned pull-pull linkage to the
>>>>>>> >> rudder
>>>>>>> > be
>>>>>>> >> more susceptible to flutter if the rudder has a counterbalance?
>>>>>>> >>
>>>>>>> >> What other types of forces are at play with counterbalances?
>>>>>>> >>
>>>>>>> >> I am just trying to find a reason for the relatively high failure
>>>>>>> > rates
>>>>>>> >> against this design.
>>>>>>> >>
>>>>>>> >> It is the same old thing- why are some people having problems and
>>>>>>> > others
>>>>>>> >> don't. (Similar story to 4-stroke exhaust headers)
>>>>>>> >>
>>>>>>> >> I will be test flying my model soon so I am obviously concerned.
>>>>>>> >>
>>>>>>> >> Regards,
>>>>>>> >>
>>>>>>> >> Peter
>>>>>>> >>
>>>>>>> >>
>>>>>>> >>
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