[SPAM] Re: [SPAM] Re: Rudder counterbalance ?
Grow Pattern
pattern4u at comcast.net
Sat Apr 30 13:12:13 AKDT 2005
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
>>>>> >>
>>>>> >>
>>>>> >>
>>>>> >> =================================================
>>>>> >> To access the email archives for this list, go to
>>>>> >> http://lists.f3a.us/pipermail/nsrca-discussion/
>>>>> >> To be removed from this list, go to
>>>>> > http://www.nsrca.org/discussionA.htm
>>>>> >> and follow the instructions.
>>>>> >>
>>>>> >> List members email returned for mailbox full will be removed from
>>>>> >> the
>>>>> > list.
>>>>> >>
>>>>> >>
>>>>> >
>>>>> >
>>>>> > =================================================
>>>>> > To access the email archives for this list, go to
>>>>> > http://lists.f3a.us/pipermail/nsrca-discussion/
>>>>> > To be removed from this list, go to
>>>>> > http://www.nsrca.org/discussionA.htm
>>>>> > and follow the instructions.
>>>>> >
>>>>> > List members email returned for mailbox full will be removed from
>>>>> > the
>>>>> > list.
>>>>> >
>>>>> > ================To access the email archives for this list, go to
>>>>> > http://lists.f3a.us/pipermail/nsrca-discussion/
>>>>> > To be removed from this list, go to
>>>>> > http://www.nsrca.org/discussionA.htm
>>>>> > and follow the instructions.
>>>>> >
>>>>> > List members email returned for mailbox full will be removed from
>>>>> > the
>>>>> > list.
>>>>> >
>>>>> >
>>>>> >
>>>>> > =================================================
>>>>> > To access the email archives for this list, go to
>>>>> > http://lists.f3a.us/pipermail/nsrca-discussion/
>>>>> > To be removed from this list, go to
>>>>> > http://www.nsrca.org/discussionA.htm
>>>>> > and follow the instructions.
>>>>> >
>>>>> > List members email returned for mailbox full will be removed from
>>>>> > the
>>>>> > list.
>>>>> >
>>>>>
>>>>> =================================================
>>>>> To access the email archives for this list, go to
>>>>> http://lists.f3a.us/pipermail/nsrca-discussion/
>>>>> To be removed from this list, go to
>>>>> http://www.nsrca.org/discussionA.htm
>>>>> and follow the instructions.
>>>>>
>>>>> List members email returned for mailbox full will be removed from the
>>>> list.
>>>>>
>>>>>
>>>>
>>>>
>>>> =================================================
>>>> To access the email archives for this list, go to
>>>> http://lists.f3a.us/pipermail/nsrca-discussion/
>>>> To be removed from this list, go to
>>>> http://www.nsrca.org/discussionA.htm
>>>> and follow the instructions.
>>>>
>>>> List members email returned for mailbox full will be removed from the
>>>> list.
>>>>
>>>
>>> =================================================
>>> To access the email archives for this list, go to
>>> http://lists.f3a.us/pipermail/nsrca-discussion/
>>> To be removed from this list, go to http://www.nsrca.org/discussionA.htm
>>> and follow the instructions.
>>>
>>> List members email returned for mailbox full will be removed from the
>>> list.
>>>
>>>
>> =================================================
>> To access the email archives for this list, go to
>> http://lists.f3a.us/pipermail/nsrca-discussion/
>> To be removed from this list, go to http://www.nsrca.org/discussionA.htm
>> and follow the instructions.
>>
>> List members email returned for mailbox full will be removed from the
>> list.
>>
>>
> =================================================
> To access the email archives for this list, go to
> http://lists.f3a.us/pipermail/nsrca-discussion/
> To be removed from this list, go to http://www.nsrca.org/discussionA.htm
> and follow the instructions.
>
> List members email returned for mailbox full will be removed from the
> list.
>
=================================================
To access the email archives for this list, go to
http://lists.f3a.us/pipermail/nsrca-discussion/
To be removed from this list, go to http://www.nsrca.org/discussionA.htm
and follow the instructions.
List members email returned for mailbox full will be removed from the list.
More information about the NSRCA-discussion
mailing list