Soptwith Pup Build

octagon · January 20, 2022, 07:50:16 PM

Finished the Beech so I started on a BUSA Sopwith Pup build yesterday. It is 1/6th scale, and has a 53 inch wingspan so it should fit in the car without having to take it apart. The wings are built in 3 sections, right, left ,and middle and then joined. I built the right wing last night and the left and the middle today and then joined them. BUSA makes great kits, although sometimes a bit of thinking is needed to understand what they are trying to say. I go by Glenns moto, you can always do something with balsa, so if I mess something up, I can fix it. But so far I think it is looking good, and the bottom wing is identical to the top, only a bit longer, so I will tacale that tomorrow.

Frank v B · January 20, 2022, 08:50:43 PM

Rob,

So the balsa delivery truck pulled up to your front door!.

re: your comment "BUSA makes great kits, although sometimes a bit of thinking is needed to understand what they are trying to say"

They have sure come a long way. I have only built one balsa USA kit and that was in about 1990. It was the Moonraker 52" span low wing .45 IC size sport/pattern plane. It was a box of balsa and a type-written one page instruction sheet that essentially said:

"Thank you for buying our kit. Put all the balsa pieces together properly, add the covering, add engine, radio and fuel. Happy flying"

After the truth in advertising requirement they should have called it a 200 piece flyable balsa puzzle.

Keep building. It's going to look great.

Frank

Photo is of the BalsaUSA Moonraker (not mine)

octagon · January 23, 2022, 09:51:07 AM

Finished the bottom wing yesterday. I find it somewhat unusual that the top and bottom wings of the Sopwith Pup were identical in chord and length. Tail feathers are next up. I will give them a go today I think.

Gregor77 · January 23, 2022, 11:02:37 AM

you are motoring! Great work!

Gregor77 · January 23, 2022, 11:06:23 AM

Once you get to the fuse, you should try to think of a way to install the batteries? I like what Jack Higgins did with his Norsman, it was a slotted nose cone, it basically removed the motor and ESC and then you twisted it on and locked it in place, it allowed for ease of battery install. The only risk was that the system was live until you unplugged the battery.

octagon · January 23, 2022, 05:27:18 PM

Thanks for the suggestion Greg. And thanks for the advice on the colour scheme earlier. I will be flying it on 2 - 4s 2200s. There are a couple of build threads on the plane and in one case the guy build a box behind the firewall and mounted the batteries vertically, right behind the firewall, accesed through a hatch on the bottom of the fuse. I have ordered an arming switch for the plane as I always hate arming a plane up side down. The kit allows for the firewall to be placed where needed to a degree, depending on the motor. I will move it as far forward as possible to help with balancing it. I worked for a couple of hours to construct the horizontal stab. Not too much work as there are a couple of good ball games on that need to be watched. I had a minor incident. I use the backing of monocote to cover the plans to protect them and make sure parts don't stick. I didn't notice that there was an area where there was none of the backing and managed to glue the stab to the plans. Not a big deal but required a fair bit of sanding to get the paper off the stab. Elevators tomorrow.

Gregor77 · January 23, 2022, 07:59:12 PM

Rob, I saw another build where the guy basically cut the cowl in half, upper and lower. He made a ply former, on both halves, then added magnets and a dowel to lock it in place. The bottom one is fixed 100% to the plane. You basically just lift the cowl off and insert the batteries (Boxes made that they sit in. A 4S will fit fine. You could use a G60 or G46 for the application. I will see if I have any Sopwith type accessories at home.

Gregor77 · January 23, 2022, 08:03:02 PM

Another thing I would do is make covers for the servos, I think the plans have them hanging out the bottom of the wing. Looks a bit nasty (Just ref the one I picked up last year)

octagon · January 24, 2022, 06:21:31 PM

The horizontal tailplane and elevators are finished, hinged and sanded. Vertical fin and rudder are finished. I will start the fuse probably tomorrow. This kit was produced 10 years ago or more and electric power then is not what it is now. The box says can be built either for gas or electric but they give no instructions of where to put the batteries. Greg's idea above is one solution. Alternately a hatch can be fashioned in the bottom of the plane and the batteries sit vertically behind the firewall. That of course means the plane has to be turned upside down to put them in and take them out. When Glenn built his 1/4 scale version he put a hatch in the side, and I could try the same thing. The real plane did have an inspection plate just behind the cowling.

Michael · January 24, 2022, 08:36:02 PM

What model will you be building next week?

Gregor77 · January 25, 2022, 02:56:01 PM

He's motoring!!!!

octagon · January 26, 2022, 07:08:48 PM

I built the fuse half yesterday, and joined them this morning. Then went flying for a couple of hours. Came home and back to work. Mounted the wing and drilled and tapped holes for wing bolts. Then the fun started. First make sure both wings at the tips are equal distance of the building board. Had to shim 1/32 of an inch to achieve it. Then trying to get the proper lower wing incidence. A frustrating hour and a half spent taking the wing on and off, sanding trying to get what the plans called for. In the end I got it but it was a bit of a tedious job, and the electric screwdriver I was using slipped off the bolt and put a hole in the sheeting of the bottom wing. I couldn't resist putting all the parts together. Then I ran around my work room making airplane sounds for 10 minutes.

Frank v B · January 26, 2022, 08:09:37 PM

Rob,

Looks like a Guillow's stick and tissue model on steroids.

re: your "Then I ran around my work room making airplane sounds for 10 minutes."

You showed such restraint. Only 10 minutes. I sure hope no-one heard/saw you or you would end up in a special ward.

Frank

octagon · January 27, 2022, 10:32:04 PM

I woke up this morning, after mounting the bottom wing last night, thinking something wasn't right. The incidence was off and the wing was not as far forward as it should have been in the saddles. Spent about 2 hours correcting it. Now I think it is good. (long, boring story). After lunch I got to start working on the fuse again. Finished the ply deck and installed the stringers for the rear deck behind the cockpit. Tomorrow servos go in.

octagon · January 29, 2022, 08:09:31 PM

I decided I would like to build the plane with a tail skid that was sprung, rather than the metal fixed one that came with the kit. The skid of course in burried in the tail after the covering is applied and is not easily accesable so I wanted to make it as foolproof as possible.
I cut out a skid and cheek block using light ply for the skid.
I then built a small bulkhead to attach the spring I was using to attach to.
I was intalling it when I happened to tork the skid, breaking it in half. I had used light ply, not thinking that it is pretty weak stuff. lucky it happend now as it would have been a bit of a bitch to replace after covering.
I remade a skid of 3/32 aircraft grade ply and replaced the broken one.
The last picture is the final configuration with the skid stained.
The setup works well, at least on the building bench.
I am using pull/pull for the elevators and rudder. I installed tubes to guide the cables, and to make installing them after the plane is covered easier. It will also make it easier to replace a cable if it needs to be.

Tomorrow the top wind instalation and all the fuss it take to get the proper incidence, but using the jig I built today, it seems like it is going to be ok.