| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 523.10 | counter-balanced rudder illustration | SPKALI::THOMAS | | Fri Feb 20 1987 09:17 | 26 |
| Kay,
What I think Dan is talking about is that some rudders have
a part of thrie surface area forward of the hinge line.
/----|
Counter / |
Balance->/ |
/___ |
Vertical/ | |<--Rudder
Stab-->/ | |
/ | |
-------------| |
Fuse | |
| /
_____________|__/
^
|
Hinge Line
I hope the picture shows how some of the surface area can be
in front of the hinge line. This area acts to balance the pressure
that the servos see when they try and deflect the surface. The forward
movement of the plane act to help the deflection and the return
of the surface.
Tom
|
| 523.1 | TRY IT, YOULL LIKE IT | PNO::CASEYA | THE DESERT RAT (I-RC-AV8) | Fri Apr 29 1988 17:21 | 29 |
| John,
The problem you're seeing isn't uncommon to models with thin-sheet
surfaces. Years back, I had a gorgeous (if I do say myself) little
Goldberg 1/2-A Skylane which exhibited the same behavior. Like
you, I tried _everything_ I could think of to rectify the situation
but the crux of the problem was the fin was just too thin. The
best I could do was minimize the flex as much as possible and forget
about it.
Know what? It didn't affect flight in the least and was totally
invisible on a low pass at 65mph as viewed from the back of a galloping
horse. My advise is to reduce the flex to a minimum and forget
it.
As to foam-board, corrugated cardboard, etc.; theres this remarkable
new modeling material on the market that is completely friendly
and perfectly suited to modeling useage. It has one of the highest
strength-to-weight ratios known, readily accepts almost any/all
glues, coverings, finishing materials etc. and is fun/easy to work
with to boot. I LOVE IT!! It's called _Balsa Wood_, you ought
to try it. ;B^} I think you'd throw rocks at all these second-rate
balsa-substitutes that are around.
|
| | 00 Adios, Al
|_|_| ( >o
| Z__(O_\_ (The Desert Rat)
|
| 523.2 | | GIDDAY::CHADD | Go Fast; Turn Left | Fri Apr 29 1988 18:39 | 21 |
| John,
As you are using three hinges I would suggest the problem is caused by the
hinges not being exactly aligned on the rudder or tail post or both.
No great problem, just increase the size of the slots and chamfer the outer
part (see fig). This is going to give you a very sloppy rudder that virtually
falls out but moves freely. To tidy things up use a hypodermic to inject some
PVA glue into the rudder and tail post hinge slots, cover with sticky tape (the
office variety); cut a slot with your exacto knife; insert hinges; pin the
hinges; and wait for it all to dry. The tape keeps the PVA in the slot, if the
glue gets into the plastic hinge it does not matter, however if it actually
joins the balsa parts together you will never successfully separate it.
| |
| _|_ | <---- Fin
+-/ | \-+
O <------ Hinge
/-\_|_/-\
/ | \ <---- Rudder
| |
|
| 523.4 | PVA = Carpenters glue | GIDDAY::CHADD | Go Fast; Turn Left | Sat Apr 30 1988 16:56 | 11 |
| Al,
PVA is a white or sometimes off white to yellow carpenters or woodworking
adhesive that is water based yet when it is dry it is water proof. It is
definitely not a silicone adhesive.
It sticks like shit to wood but will not stick to plastics. I use it to stiffen
up worn hinge slots. Some people use it for building but I think it is too
heavy and takes too long to set.
John.
|
| 523.5 | | CLOSUS::TAVARES | John -- Stay low, keep moving | Mon May 02 1988 10:35 | 25 |
| Thanks for the info, John. The PVA you refer to is called
aliphatic (sp) resin here, the most common example is Titebond.
Sometimes Elmer's is referred to as an aliphatic, but its not.
Yes indeed, it does stick.
I've tried your method to a certain extent, by making the slots
for the hinge longer and adjusting the hinge up and down. I'm
beginning to suspect that its not vertical misalignment that
causes my problem, but rather horizontal misalignment. In any
event, I'll cut the lower hinge slot (the others are perfect) a
little wider and see if that works.
Using your method, it seems that the parts must be covered before
you inject the glue; that is, its part of the final assembly???
I still think that making the rudder post longer and mortising it
into the tail post is the hot set-up.
Also, the tailwheel hangs off a plastic tailwheel bearing piece
and slides into a little slot in the rudder. While we're looking
at that corner of the plane, I invite good advice on setting up a
steerable tailwheel. I thought that the bearing piece, with the
wheel collar was the only way to go, but this weekend I saw one
hung directly off the rudder on a .40 size ship. The builder
didn't seem concerned that it puts a load on the rudder.
|
| 523.6 | ALIPHATIC RESIN.......?? | PNO::CASEYA | THE DESERT RAT (I-RC-AV8) | Mon May 02 1988 10:58 | 12 |
| John,
Re: .-1; that sounds a whole lot like what we call "aliphatic-
resin. A couple of domestic brand-names come to mind: Tite-Bond
(which is a woodworker's glue which found favor with modelers) and
Pica Glu-it.
|
| | 00 Adios, Al
|_|_| ( >o
| Z__(O_\_ (The Desert Rat)
|
| 523.7 | HE'LL BE SORRY.....! | PNO::CASEYA | THE DESERT RAT (I-RC-AV8) | Mon May 02 1988 11:57 | 20 |
| Re: .6,
This reply applied to note .4 by John Chadd (John Tavares snuck
.5 in while I was still writing).
Re: .5,
John (Tavares),
The fellow you mention with the tailwheel mounted directly to the
rudder _will_ become concerned with his installation when he starts
having to replace rudder hinges on a frequent basis. The best
tailwheel setup is _any_ setup which isolates the rudder from tailwheel
shocks/loads.
|
| | 00 Adios, Al
|_|_| ( >o
| Z__(O_\_ (The Desert Rat)
|
| 523.8 | Check Hinge Allignment | LEDS::WATT | | Tue May 03 1988 08:40 | 9 |
| One possible problem could be the hinge allignment. All of the
pins should be in line and all hinges should be in plane. If not,
twisting forces are generated when the rudder swings. It should
be free and the torque to move it should be constant. Moving the
hinges that are out of allignment is the only solution. It is
important to get the hinges centered on the rudder and post.
Charlie
|
| 523.9 | | BSS::TAVARES | John -- Stay low, keep moving | Tue May 03 1988 10:30 | 5 |
| Last nite I used John Chadd's procedure. I widened the slot with
a dental tool chisel and put the hinge in. Then I fitted pieces
of 1/32 balsa in there until the hinge was tight and the rudder
swung freely, and zapped the whole works into place. Works
pretty good.
|
| 523.11 | rudder hinge comments by Al Casey | BRAT::RYDER | perpetually the bewildered beginner | Mon Oct 01 1990 01:47 | 11 |
| extracted from a RAMBLIN' by UPWARD::CASEYA, -< REPLIES, REPLIES....... >-
--------------------------------------------------------------------------------
.
.
Regarding the rudder hinges, they seem to take more of a beating _even_
when the tailwheel is isolated. Even the scale like, leaf-sprung units
driven by springs from the rudder still impart additional strain on the
rudder, vis-a-vis the hinges, and my experience has consistently been
that rudder hinges are invariably the first to fail. Therefore, I like
to use an extra hinge or two to beef things up a tad.
|