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Old Apr 09, 2012, 05:55 PM
Flies jets for a living
crjdriver87's Avatar
United States, KY, Louisville
Joined Sep 2011
35 Posts
Build Log
1/8 Scale Sopwith Pup Build from Short Kit

I think I was born in the wrong era! I have always loved the warbirds of yesteryear so much. To me they just look so cool in the air and on the ground. Huge wheels, wooden props, fabric, flying wires, and machine guns strapped the the airframe! Well I've always had a thing for the Sopwith Pup and am getting so sick of building these doggone ARF's that are a dime a dozen that you see multiple of the same plane at the flying field I decided to try to get back into building kits from the ground up. I ordered the Aerodrome RC 40" pup and have been very impressed with their customer service. I would recommend them to anyone ready to break the mold and get back to what R/C is all about...gluing your fingers to balsawood by accident.

So at the risk of being ridiculed and mocked by seasoned scratch builders and pros, I decided to document my progress of the kit. I hope to do the kit justice but I'm sure that, with the quality that this kit has, it shouldn't be too hard. Here we go...this should be fun.
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Old Apr 09, 2012, 05:58 PM
Flies jets for a living
crjdriver87's Avatar
United States, KY, Louisville
Joined Sep 2011
35 Posts
Okay so here is what we're dealing with...
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Old Apr 09, 2012, 06:05 PM
Flies jets for a living
crjdriver87's Avatar
United States, KY, Louisville
Joined Sep 2011
35 Posts
I began by building the horizontal stab, vertical stab and of course the rudder and elevator to begin. So far the only wood I've had to supply are the 1/8"x1/8" balsa strips to be cross-braces. I'm amazed at how light they are after building them....this could be a very light model (they say about 30 oz when finished). I'm sure mine will be a bit heavier as I'm probably gonna use some iron-on covering that looks opaque so any suggestions would be helpful. I was thinking parklite by Ultracote but I have no experience and don't know if their olive drab is opaque or transparent.
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Old Apr 09, 2012, 10:28 PM
What's 3D?
trumps's Avatar
Australia, WA, Ellenbrook
Joined Feb 2008
3,318 Posts
great choice of model, imho not a lot looks prettier in the air and is as nice a flyer as as a pup!
Aerodrome produces fantastic kits, i have built their Pfalz DIIIa, and it was a great build, and a fantastic flier, their pup will be the same. several years back i built a Peter Rake pup, also 40'' span, very similar in construction, mine came out at a slightly porky 36oz due to having to add a fair amount of lead to the cowl to get the cg, make sure you get all the servos ect as far forward as you can, you really need to keep the weight forward with these short nosed rotary engined models. mine still flys magnificently even at it's weight, and is very scale in the air, still my favourite flyer! i am sure you will love the build, and am looking forward to following your build.

BTW, don't know if you have had a read through this thread, hammerd built a magnificent Aerodrome pup, and it is well worth a look!
http://www.rcgroups.com/forums/showthread.php?t=1085403

Cheers
Craig
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Old Apr 10, 2012, 03:56 PM
Flies jets for a living
crjdriver87's Avatar
United States, KY, Louisville
Joined Sep 2011
35 Posts
Trumps, thanks for that information. I checked out the thread. You all sure did a great job with those Pups. They look outstanding. I'm hoping mine comes out 1/2 as good looking and I'll probably be thrilled. I am actually leaning toward a scheme like the one you have done although I plan on making the wheels red to match the cowling.

Speaking of cowling, that was my project today. Basically it involves 1/32" plywood sheeting to be cut just over an inch wide and wrap it around the two plywood pieces included to give the cowl its shape. I bought some birch plywood sheeting for about $8 from the craft store the other day to be used for this purpose. The most difficult part is securing the plywood to the circular shape of the first "C1" piece. Most people would use clamps of some sort to secure it, however, I am fresh out of them and although a very strong clothespin would work (don't have any of those either), I used a simple but effective #64 rubber band to wrap all the way around the circumference of the outside of the plywood to keep it in place on the first former until I was able to tack it in place with some CA. Then I mixed the epoxy and glued the inside all the way around to secure in place. After the first piece was glued the second former is easy to slide into position and, again, wrapping a rubber band around it and tacking with CA, I was able to get the plywood to hold the shape as the epoxy cured.

The next step is to glue a few layers of 1/4" (I think) thick balsa circles around the front of the cowl. These are here so that the sanding of the proper shape will be much easier. Even with them in place and dry, I believe that some filler will definitely be necessary in order to get a really good seamless cowl in the end. Ran out of time today but I'll probably start on the sanding and wheels tomorrow.
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Old Apr 10, 2012, 09:08 PM
What's 3D?
trumps's Avatar
Australia, WA, Ellenbrook
Joined Feb 2008
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looking good mate, with regards to filler, see if you can pick up a tub of Red Devil filler, it is really light weight stuff, and sands like balsa, nice and easy. i also use automotive spray putty to fill the grain and get rid of any blemishes before painting, this can really be brought up to a near mirror finish when gone over with fine emery paper, and can be painted straight over.

a couple of little vids of my pup in action.
R/C Sopwith Pup at Yokine reserve (3 min 22 sec)

Peter Rake Sopwith Pup, 2nd flight (6 min 37 sec)


Craig
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Old Apr 11, 2012, 07:21 PM
Flies jets for a living
crjdriver87's Avatar
United States, KY, Louisville
Joined Sep 2011
35 Posts
Those videos are very nice. It looks very scale in the air and I am still impressed with the looks of that model. Thanks for the info on the filler although I actually just used some from the hobby store today and the cowl is beginning to take shape. I was interested in how best to "seal" the cowl before painting and you said that the spray putty is a good option? Is there a particular brand I should look for? I hope to seal it pretty soon but I'm gonna be on a four day trip starting tomorrow so I'll be away for a little while.

So aside from beginning working on the built up cowl, I was able to get the tires assembled today. As far as the cowl goes it seems very tedious, yet I think I'm going to like the wood cowl much better than a plastic type of cowl. The wheels are just balsa cores sandwiched between two pieces of plywood (all included) and then a 3/32" brass tube to go through the ties in order to create a hub. Can't wait to get back to work on this pup but with my trip and then finishing up an Alien Aircraft Piper Cub when I get back not sure how much time I can devote to it for the next week.
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Old Apr 11, 2012, 07:23 PM
Flies jets for a living
crjdriver87's Avatar
United States, KY, Louisville
Joined Sep 2011
35 Posts
Craig:
In addition to the question about the putty as a sealer, what sort of power system are you running on your pup and, secondly, what did you cover your plane with? Thanks.
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Old Apr 11, 2012, 07:35 PM
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Canada
Joined Nov 2000
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Krylon spray laquer (clear) is Fine/ideal as a sealer.
Auto type rattle can primers used to be laquer based but Eco rules have dicked with most of them. Also be careful as primers are full of Talcum powder which builds weight surprisingly quickly... So sand off almost ..all of the primers you apply.
I say this as Laquer/dope still remains as the best /lightest way to seal bare balsa.
Lightweight fillers are available for a fraction of Hobby Shop prices in the Plaster/ Drywall patching area of Home Depot.
PS: the Sopwith 1 1/2 strutter has a happier / longer nose moment
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Old Apr 11, 2012, 08:51 PM
Flies jets for a living
crjdriver87's Avatar
United States, KY, Louisville
Joined Sep 2011
35 Posts
I actually have some krylon lacquer matte finish around the house I suppose I could use to seal it. I'll have to try it out. Thanks
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Old Apr 11, 2012, 10:13 PM
What's 3D?
trumps's Avatar
Australia, WA, Ellenbrook
Joined Feb 2008
3,318 Posts
Quote:
Originally Posted by crjdriver87 View Post
Craig:
In addition to the question about the putty as a sealer, what sort of power system are you running on your pup and, secondly, what did you cover your plane with? Thanks.
heya mate
As Bare says the spray putty does need to be well sanded out, but i find it gives a great finish and with it being a different colour than the surrounding balsa is very easy to differentate between any high and low spots on the surface. i usually knock it down with corser paper, and end up down to 2000 grit paper to finish for a mirror finish. it is just a generic brand spray putty that i use from one of the local autopro stores.
with regard to power systems, i wanted to run a scale sized and profiled prop which was cut for me by vintage1 from mahogany, and assembled and shaped by me, it's measurements are 11.5 x 11.6 so is an odd size, it was originally powered by a hobbyking DT700 on 2S2200 and produced a mere 54W/lb and although very scale in performance it really kept me on my toes with its marginal
power and longish takeoff runs, i changed the motor to a DT750, which although only adding only 10ish W more power gave the model a bit more authority.
with this setup it still requires a reasonable takeoff run, and very gentle liftoff, but cruises around very sedately at slightly over half throttle, needing full throtle and a gentle dive to produce a nice round loop. it's probably not the ideal setup as a relaxing everyday flier, but once used to it's performance (or lack thereof) has proven totally reliable, and very scale in look and performance with the prop turning at little over 3000rpm flatout!
as to covering, i used litespan due to its light weight, and non glossy slightly textured finish, polyspan would work equally as well, and they both take paint extremely well. enjoy your trip

Cheers
Craig
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Old Apr 27, 2012, 12:19 PM
Flies jets for a living
crjdriver87's Avatar
United States, KY, Louisville
Joined Sep 2011
35 Posts
We it has been a long time since I posted any progress here but with finishing up the Cub and also beginning a non-aviation related side job in addition to being gone on trips has slowed down progress! At least I have been able to make a little progress. First I'll show you what I've been working on, having just finished the details the other day before beginning what little progress I made on my pup.

This is the Alien Aircraft J3 Cub. Very fun and extremely simple build and it flies very well for a small electric. I felt as though I was flying a much larger bird when it was in the air. The only trouble I had with the kit was the provided plastic for the windshields was totally cloudy and very opaque. I didn't want to put that on a relatively scale model so I had my family help me drain a few 2-liter bottles and used that plastic for the windshields instead. Surprisingly it turned out pretty well. It has tons of power on a Value Hobby 400 outrunner, 18 amp esc and 11.1v 1300mah battery.
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Old Apr 27, 2012, 12:34 PM
Flies jets for a living
crjdriver87's Avatar
United States, KY, Louisville
Joined Sep 2011
35 Posts
I was able to get started on the fuselage the other night. I didn't have a whole lot of time so I am about halfway through the fuse construction. Although the plans call for 1/8"x1/8" hard balsa for the longerons, I had to use 1/8"x1/8" basswood as its all I had access to. I don't think it should be a huge factor as far as weight goes...I know to avoid building tail-heavy. The rest of the fuse has gone together pretty simply.
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Old Apr 27, 2012, 05:05 PM
What's 3D?
trumps's Avatar
Australia, WA, Ellenbrook
Joined Feb 2008
3,318 Posts
Fantastic looking Cub mate, very nice! The fuse is looking great on the pup as well!

Craig
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Old Apr 27, 2012, 05:46 PM
I eat glue
Canada, NS, Yarmouth
Joined Jul 2006
3,535 Posts
Good job. I've got the Peter Rake 40" Pup on the go around here somewhere.
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