| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 1024.1 | Flap drive system | NAMBE::TTOMBAUGH | 20/20 Vision&walkin'round blind | Mon Jan 28 1991 10:03 | 33 |
| Jim,
I don't know if the fuselage will be built up balsa or fiberglass
but the flap drive method that Dodgson uses in his kit works well
and can be used in either type of fuse.
You have to have a method that will allow for slop and misalignment,
wing movement, etc. Dodgsons' does that, the square tube system
may not.
Dodgsons system uses two pieces of 1/16" music wire bent at 90 degrees.
One leg from each piece runs through a brass tube inside the fuse.
The other legs project outside the fuse. and have a short length
of wire coiled around them. The free end of the wire is inserted
into a tube in the inbd. end of the flaps. The wire is free to move
on the rod and free to slip in and out of the flap tube( which it
can't do when the wings are plugged on.)
A nylon control horn with a metal sleeve and allen head set screw,
Du Bro makes several sizes, is slipped over the brass tube in the
fuse. , and the set screw is tightened down on the music wire through
a small hole drilled in the tube. The flap servo is hooked to the
horn with any convenient length pushrod.
In the event of a hard landing the wings are free to move outbd.
without damaging the flap drive, or if the flaps hit the ground
hard the set screw will slip on the drive wire, if not torqued too
tight, saving the servo gears and flap structure.
This is about 10 times more complicated to read about than it is
to do.
Terry
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| 1024.2 | Sounds interesting but I can't quite picture it | ZENDIA::REITH | Jim Reith DTN 226-6102 - LTN2-1/F02 | Mon Jan 28 1991 10:23 | 11 |
| Thanks Terry.
It IS pretty difficult to read/understand. ;^)
The fuselage is built up and there isn't any access built in below the
wing. If I understand you correctly, the wires go into the flaps and
the ends cross under the horn so that the horn set screw holds them
together once the wings are in place? I suppose I'd need a hatch on top
to access the set screw during assembly?
Thanks for the help but as usual, I think I'm confused...
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| 1024.3 | More flap drive | TULA::TTOMBAUGH | 20/20 Vision&walkin'round blind | Mon Jan 28 1991 11:01 | 19 |
| You've got the basic concept Jim. Both wires go inside the brass
tube. One wire is CA'ed into the tube permanently. The other is
captured by the set screw. When the horn rotates the tube , both
wires rotate with it. The horn is set off center to be over the
unglued wire.
The set screw is set at an angle pointing down and a small hole
is drilled in the bottom of the fuse. to allow access with a long
allen wrench.
This method was intended for a fiberglass fuse. where no access
to the wing t.e. area is possible inside the fuse. With a built
up fuse. the flap drive mechanism could be installed before the
top is slapped on.
I could send you a copy of the relevant portion of the plans I
have, if you'd like.
Terry
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| 1024.4 | Guess I'm just missing the simplicity of it. | ZENDIA::REITH | Jim Reith DTN 226-6102 - LTN2-1/F02 | Tue Jan 29 1991 08:04 | 13 |
| Now I'm MORE confused ;^)
Is there a total of two wires or a total of 4 (2 per panel)? With the
wings plugging in with some dihedral the wires from opposite sides
aren't able to join like you specify and in order for the wings to be
removed I would think I need to release the set screw to withdraw the
wing wire. I think I need the picture...
Jim Reith
LTN2-1/F02
Or I can find out the number for the Fax machine in the next office if
that's convenient.
|
| 1024.5 | More on Dodgson Flap linkage | KAY::FISHER | Stop and smell the balsa. | Tue Jan 29 1991 08:49 | 164 |
| > Now I'm MORE confused ;^)
I'll try add to the confusion. I consider myself an expert on the Dodgson
flap mechanism since I put my Lovesong flap mechanism together the last few
days.
Now to try and draw some things.
End view of flap looking from the center of the wing towards the tip.
__-~|<----- Hinge point
__-~ |
__-~ |
_-~0___________|
^ This is the hollow brass tube inserted into the flap.
Front view of Flap, Left is the inside edge, Right is towards the tip (Aileron).
-------------------------------------------------------------------------------
| |
| |
| |
|=========_________________________________________________________________|
^ There is that brass tube again but notice that the top of the flap
skin (Balsa and Fiberglas) hangs over the edge. This is to allow room
for the flap mechanism but hide it from the top view of the wings
when mounted on the fuselage.
Simplified top view of the fuselage, Left is forward, Right is aft.
______________
/ ____________|
----------------------------------| |-------------------------------------------
| |
| |
|_|
_
| |
| |
| |
----------------------------------| |-------------------------------------------
\ ------------
--------------|
These are two thick (maybe 3/16" on a large glider (Lovesong) pieces of
music wire bent to 90 degree angles and not shown are the brass bushings.
You drill two holes in your fuselage and stick small hollow brass bushings
in the holes then stick the 90 degree music wires thru them.
Now you put a sleeve of brass in the center to fasten the whole works together.
Top view of the fuselage, Left is forward, Right is aft.
______________
/ ____________|
----------------------------------| |-------------------------------------------
|| ||
|| ||
||_||
| _ | <-Hollow brass tube holds flaps arms
|| ||
|| ||
|| ||
----------------------------------| |-------------------------------------------
\ ------------
--------------|
Now my directions differ from the previous ones in that Dodgson says to solder
the brass in the middle - this of course leaves no adjustment but you could
always unsolder to adjust a tad.
But we forgot to add the control arm - so before we solder we must also
slip on a control arm. This is a nose wheel steering arm.
Top view of the fuselage, Left is forward, Right is aft.
______________
/ ____________|
----------------------------------| |-------------------------------------------
|| ||
|| ||
||_||
_| _ |_
________/ || || |
|________ || || |
\-|| ||-
----------------------------------| |-------------------------------------------
\ ------------
--------------|
Now in reality the flap arms are mounted kinda high in the wing and the flap
control arm (nose wheel steering arm) actually hangs more straight down
and you adjust for correct throw. In fact it actually will end up pointing
aft quite a bit if the flaps are raised as they are in the above diagram.
However the diagram is correct because it is assumed that you haven't tightened
the set screw on the control arm yet.
Now lets talk about the arm sticking out the side of the fuselage.
Top view of the fuselage, Left is forward, Right is aft.
----------------------------------| |-------------------------------------------
\ ------------
--------------|
^ just this part now is all we want
to be concerned with.
We want to put a piece of music wire on the end of this arm that is the same
diameter as the inside diameter of the hollow brass tube in the flap
and we want it to be free to rotate up and down and travel forward
and aft on the control arm.
So we take a piece of music wire and bend the end in a circle so that
it looks like an eye hook.
So you have a piece of music wire maybe 1.5 to 2 inches long with a loop
at one end. Slip the loop over the flap control arm above.
Top view of the fuselage, Left is forward, Right is aft.
----------------------------------| |-------------------------------------------
\ ---------#--
-----------#--|
#
#
# <-- Music wire hooked on end
# of flap arm
#
Since it slipped on the arm so easy it is free to travel forward and aft.
(Left and right on this drawing) and to pivot up and down.
Now it would be nice if this music wire wouldn't keep falling off the flap
arm so we take the 90 degree flap arm over to our anvil and whack a flat
spot in the end of it so the music wire cannot come off the end.
Remember there are 3 brass bushings not shown. Two are in the fuselage sides
where the 90 degree flap arms pass thru. Be careful not to let any solder
get to this area! The third one is between the music wire hooked onto
the control arms (shown) above. The way Dodgson does this is the music wire
is actually bent around a brass eyelet (probably purchased from a notions
store or salvaged from the shoelace eyelets from some old boots).
So to put this all together you have to sorta do things in reverse order from
my description. That is you better put the music wire on the 90 degree arms
and flatten the end before you put the arms in the fuselage.
You also have to put the control horn on the brass center section and place
it in the fuselage before you slide the 90 degree arms into the fuselage.
Don't forget the two extra bushings here. They slide the control horn off
the center section temporarily till after you solder it. Just before
you solder - you have to mount wings and make sure everything is aligned.
After you solder the center section then epoxy the brass bushings in place
that hold the flap control arms.
Did I make it more complicated or less?
Bye --+--
Kay R. Fisher |
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| 1024.6 | Dodgson flap linkage corrections | KAY::FISHER | Stop and smell the balsa. | Tue Jan 29 1991 08:59 | 18 |
| Corrections already...
>You also have to put the control horn on the brass center section and place
>it in the fuselage before you slide the 90 degree arms into the fuselage.
>Don't forget the two extra bushings here. They slide the control horn off
^^^^ Then
>the center section temporarily till after you solder it. Just before
>you solder - you have to mount wings and make sure everything is aligned.
Warning - take the wings and everything else that you don't want to burn
out now when you solder.
Bye --+--
Kay R. Fisher |
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| 1024.7 | Dawn breaks over Marblehead | ZENDIA::REITH | Jim Reith DTN 226-6102 - LTN2-1/F02 | Tue Jan 29 1991 09:10 | 11 |
| A picture AND a 1000 words!
Now I understand (if Terry concurs with your description)
I was picturing something similar to standard aileron linkage with the
hinge line rods split. This makes perfect sense and I think I can even
build it ;^)
Your showing your hinge line on top rather than on the bottom? Are these
spoilers rather than flaps in your setup (pop up rather than extend
below?)
|
| 1024.8 | Obscene flap art | NAMBE::TTOMBAUGH | 20/20 Vision&walkin'round blind | Tue Jan 29 1991 09:54 | 14 |
| Kay's pictures are exactly what I meant.
Thin CA can be used to hold the rod in the tube, and avoid the solder
danger. In fact it must be used in one piece fuselages where no
top access is possible, ie, Sealy designs. Also a small piece of
tube can be CA'ed on the rear of the coiled wire to prevent it falling
off the rod, rather than whacking a flat on it. And lastly, a large
paper clip can be used rather than music wire, to coil around the
rod. Much easier to bend coils in.
Oh yes, the drive tube in the flap needn't be right at the trailing
edge. By moving it forward into the thicker part of the flap, you
gain some strength. This is the area that will break first if the
flaps are able to drag on the ground in the full down position.
Terry
|
| 1024.9 | Thanks for the valuable technique | ZENDIA::REITH | Jim Reith DTN 226-6102 - LTN2-1/F02 | Tue Jan 29 1991 10:23 | 12 |
| I had expected that the tubes in the flaps wanted to have a little more
meat around them. I'm considering using nylon tubes in the flaps and
slipped over the rods to avoid electrical (scrape scrape) noise. The
eyelets can be found in C/L leadout sets which is also a good source of
heavy braided cable for pull-pull rudders. Some of the old parts
packages used to have an eyelet where they hung on the wall (Perfect?)
that worked well.
I must say that I appreciate Kay's effort to put the 150+ lines into
the file to share since he and I will be flying at lunchtime today.
This series of notes might be easier found if moved to the FLAPS topic
|
| 1024.10 | Dodgson Flap linkage correction | KAY::FISHER | Stop and smell the balsa. | Tue Jan 29 1991 14:57 | 10 |
| > Your showing your hinge line on top rather than on the bottom? Are these
> spoilers rather than flaps in your setup (pop up rather than extend
> below?)
You caught a mistake - they should have been hinged at the bottom.
Bye --+--
Kay R. Fisher |
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