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Old Sep 22, 2011, 06:28 PM
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Steve L Allen's Avatar
United States, CA, Paso Robles
Joined May 2011
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Build Log
1/6 Balsa USA Pup - Different Details

I'm a good way through the build of a Balsa USA 1/6th scale Sopwith Pup. Since this plane has seen a number of build logs and there isn't anything new to add to the basic build of the plane, I thought I would focus just on the different details or other ways I'm approaching my project.

To start off with I have included some pictures of the cockpit area. With a plane this size I can see no reason not to include a full cockpit. I always think one of the more attractive details on a plane model is the cockpit itself.

What I'm working on here is the cockpit floor and the seat. I am using the lightest materials that I can to keep weight down. The floor is very thin ply and the metal plates for the pilot's boots are painted 3X5 card material. The seat is also thin ply which I cutout in the shape of a seat, soaked it in water and rubber banded it around a paint can so that it would pick up the shape.

The floor and interior framing of the fuse are stained since they will be visible through the cockpit opening.
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Old Sep 23, 2011, 04:51 AM
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United States, NY, Dobbs Ferry
Joined Oct 2008
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more photos please! i am just getting ready to start one of these and would love to see your progress. have you decided on a power setup? love the cockpit!

ST
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Old Sep 23, 2011, 08:50 PM
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San Bernardino California U.S.A.
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Yes! More photos .....

..... please.

Me, Im working on a 43" WS Spad, from plans I got from Flying Models magazine, from the mid 1960s, scratch built

So Id like to see what your up to, deffinetly!

Laramie.
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Old Sep 24, 2011, 05:35 PM
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Another thread on this model won't hurt, I've been wondering as to whether I'd build one in the future, so yes I too would love to see more.

s.
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Old Sep 28, 2011, 03:04 PM
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Steve L Allen's Avatar
United States, CA, Paso Robles
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The cockpit is coming along and I'll post some more pictures soon. The challenge is that the details of the cockpit are hard to find and vary considerably among those restored and replica birds that are still around. In WWI they really didn't take many detailed pictures that I have been able to find. So I'm sort of combining elements from the pictures I have and from other similar planes, the Camel etc, to build my cockpit.

I haven't settled on the complete electrical system yet.

This has been a great kit. Very complete and the instructgions are excellent. If you build one, I really recommend following the manual in order. They are very detailed in their instructions and the pictures really help.
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Old Sep 28, 2011, 03:45 PM
Visitor from Reality
United States, VA, Arlington
Joined Dec 1996
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A Pup - great! THough I never got to see Old Warden's fly, I have always fancied doing one of these. Not sure if I have the room to build and store one now, so I'll just tag along on the thread for second hand thrills.

In the meantime, if anyone wants a Pup that looks different, the Shuttleworth Collection have been tinkering with their again. This would stand out in the pits for sure:

http://www.werkost.com/shuttleworth.htm

Airborne:
http://www.flickr.com/photos/shuttle...n/photostream/
http://www.pprune.org/aviation-histo...ies-again.html

This one is somewhat different. It actually started life as a post WW1 Sopwith 'Dove' - a two seater with swept back wings that was closely based on the Pup. Old Warden converted it to a Pup and still fly it to this day. As with all their restorations and new builds, when aircraft are major serviced to include re-covering, they are refinished as a different example. When I used to go to OW almost monthly, the Pup was green on the top, cream underneath basically.

How is this kit for weight of structure? Also, what are you using for power?

Good luck with your project

Dereck
Hope that helps
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Old Sep 29, 2011, 05:45 PM
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Here are some additional pictures. The pilot seat is part way along and placed in the fuselage to check sizes etc.
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Old Sep 29, 2011, 05:52 PM
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I think the structure of the kit is solid without being too heavy. Overall I can't complain about the way it goes together. There are a few things I would like to see done differently; the ailerons are designed a little funny around the hinge points. They'll work fine but there will be a large gap on the bottom side of the wings between the wing itself and the aileron.

I haven't worked out all the power details yet. I am leaning toward having the cowl, motor, batteries and speed control slide in and out of the nose as a unit. Might be easier to locate the batteries further forward for better CG. We'll see how that works.

In the meantime, the cockpit detailing will go forward.
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Old Oct 11, 2011, 06:38 PM
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One of the details I was considering was pull-pull controls for the elevator and rudder. It wouldn't be too difficult and would certainly enhance the scale looks. But I got to thinking about the added complication of the mechanics involved and how much greater an opportunity it presented for things to go wrong mid-flight. On a straight set-up with push-pull control rods there are 4 connections total. Two for each control surface. Easily adjustable and secure clevis attachments would mean there would little chance for failure.

Whereas the pull-pull arrangement means 4 connections for the rudder and eight connections for the elevator. The attchment points to the servo control arm using Dubro fittings are a push fit lock washer and a set screw for the cable. All of which hightens the risk of them loosening up in flight. Also, the lower wing is a fairly big job to remove so checking and performing maintenance would be a pain.

If anyone has any thoughts I would sure welcome them. Otherwise, I think I will break with scale and go with control rods and the saftey and simplicity they offer.
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Old Oct 11, 2011, 11:08 PM
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Moab, Utah, USA
Joined Apr 2003
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On my Bristol Scout I used pull-pull on the elevator, rudder and ailerons. They are definitely more difficult to set up. Using it on the ailerons is probably more work than it's worth unless you are a dedicated scale efficionado. With short nosed aircraft like these though, getting the CG right is difficult at best and using pull-pull on the tail feathers pays dividends in weight distribution. Pushrods are heavy and pull-pull is almost weightless. And any weight pushrods add to the tail will have to be compensated by four times as much in the nose.

Larry
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Old Oct 15, 2011, 09:44 AM
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I am in for the seeing. I love this plane...
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Old Oct 17, 2011, 06:28 PM
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More Pictures

Here are a couple of pictures of the fuselage in process along with the elevator and rudder pinned in place.
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Old Oct 17, 2011, 06:31 PM
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I'm still exploring the pull-pull set-up for the tail surfaces. I have some .30 braided beading wire coming so I'll see if that is robust enough to do the trick. I want to locate some plastic tubing to run the cables through. That way I can install the system, remove it and cover the fuselage and then slide the cables back in place with no problem.

The Pup's upper elevator cables enter the fuselage pretty high and then have to bend down under the cockpit floor to the servos mounted near the firewall.

If anyone has a good source for the tubing I'd appreciate the help.
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Old Oct 17, 2011, 10:30 PM
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Quote:
Originally Posted by Steve L Allen View Post
One of the details I was considering was pull-pull controls for the elevator and rudder. It wouldn't be too difficult and would certainly enhance the scale looks. But I got to thinking about the added complication of the mechanics involved and how much greater an opportunity it presented for things to go wrong mid-flight. On a straight set-up with push-pull control rods there are 4 connections total. Two for each control surface. Easily adjustable and secure clevis attachments would mean there would little chance for failure.

Whereas the pull-pull arrangement means 4 connections for the rudder and eight connections for the elevator. The attchment points to the servo control arm using Dubro fittings are a push fit lock washer and a set screw for the cable. All of which hightens the risk of them loosening up in flight. Also, the lower wing is a fairly big job to remove so checking and performing maintenance would be a pain.

If anyone has any thoughts I would sure welcome them. Otherwise, I think I will break with scale and go with control rods and the saftey and simplicity they offer.
I've used 'scale' pull-pulls on several scale models and even on some non-scale. My Flair Magnatilla, built in the last century and smelling of old caster oil, had separate elevator halves 'wired' to the one ele servo and did just fine. On my DH53 Hummingbird, back in England early 1990's, I made what looked like the full size's elevator cross bar with each side driving its adjacent elevator, plus pull-pull on the rudder.

Look at placing either your servo itself or bellcrank to transfer its drive - say, if you put the servos on the back of the firewall - so the wires can go through close to where the full size control runs started life on the bottom of the control column, then out to do the job via a scale run. If you lay it out like the full size, then figure passage through the covering, you can close to lay it all out pre-covering, then feed it in from the back end post covering and hook it all up. Okay, takes time, but its light and will do the job well enough.

With that phenominal job you've done on the cockpit area, you can't have Goldenrods waggling your controls - please, pretty please.

But would agree with Larry - never plucked up the courage to do a full blown closed circuit aileron control set-up. But please put the aileron servos inside the wing, not hanging out of the wing bottom. Should do fine with two good steel geared BB servos in the lower wing and thin pushrods in scale location to the uppers.

Easy to put dummy closed loop simulation on the top wing - just a scale looking control horn with thin wire going into the wing. They waggle appropriately when the ailerons move and thus look the part on the ground.

Great model, good luck

Dereck
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Old Nov 02, 2011, 02:22 PM
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Cockpit Progress

Here are some more pictures of the progress on the cockpit.

The seat has some piping around the edges to give it some substance and the rudder pedals have been carved up out of balsa to try and save as much weight as possible. The control column is wood dowling with some wire wrapped in string for the grip.

The control cables and support cables inside the fuselage are various sizes of braided wire and beading wire.

Next up is the instrument panel and I'll get some pictures out on that soon.

I also elected to go ahead with the pull-pull method for controlling the rudder and elevator which should perserve weight aft of the CG and give a more scale effect.
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