Jemima Again

[Fredrum]

Thanks for the advice Onetenor. All taken on board. For the glazing, I've used soft drink bottles which have a smooth section under the label just the right for the side panels. The chances are that i will need larger sections in the future, so I'll keep my eye out for acetate packaging

The model is essentially finished now and I have very much enjoyed the build. An issue arose when I banded the wing on. The largest bands i could find are 8". There is not a huge amount of pressure on the wing, but there is quite a lot of backward pressure against the back stop due to the relative positions of the front dowel and the L.E.

I’ve probably not made as good a job as I should have in the structure behind the wing seat and I’m finding that the right side of the seat is flexing back a little causing the wing to skew slightly. I put in some reinforcing pieces here, but it doesn’t seem to have helped.

I might rethink the mounting system and look into using bolts instead, or I might be able to come up with another knock-offable system, or i might bit the bullet and take the covering off the turtle deck and do a little engineering, although I'm reluctant to add any more weight behind the CG. It may even be possible to move the front wing dowel closer to the L.E. Any advice would be very welcome.

[Fredrum]

Time to ‘fess up to a couple of issues

I contacted the local flying club and they graciously invited me to the field where they would be happy to check over the model and maiden it for me even though I’m not a member. While preparing for it, it tseems that the plywood rudder horn was too flimsy and it snapped off so I headed down to the electronics store and bought a small sheet of fiberglass board to make a new one which was a bit deeper, front to back. While I was at it, I shortened the distance between the clevis holes in order to increase the rudder travel and bushed them in brass. The remains of the old horn were cut out and the slot extended into the rudder to increase the gluing surface.

The other problem I encountered was that while reassembling the tail, the threaded insert inside the fin came adrift, which meant that I couldn’t screw it on, so I glued it on instead after removing some covering. In the end, it’s much more solid and better aligned. It also meant that I could leave off the attachment bolt, which saved a bit of weight where it matters most. I’m always happy when I can make a virtue out of disaster. Once it was all back together, the rudder throw was exactly as recommended at full servo travel.

The plane was a little tail-heavy as built so I hammered some sinkers flat and bolted about 150g to the back of the firewall (electron wall?) to balance on the main spar. All up weight is 1.6kg (3lb 8oz). All ready for the maiden tomorrow.

[Jim Newberry - Nuviation Ltd.]

That looks great Fredrum! Let us know how the maiden goes.

Jim.

[Fredrum]

Cheers, I'm pretty pleased with it and I've really enjoyed the build even though it's turned into a bit of a long-term project.

Down at the field today and many compliments on a very attractive model (thanks Jim). Strangely, even though there were some excellent and very experienced pilots there, none of them built their own models so Jemima was a bit of a novelty for them.

Initially I had a range problem with the radio so one of the guys donated a new receiver that he had with him and his transmitter. I was advised that the best man for the job of piloting the maiden flight was the club president, who agreed to give it a go.

We set up low rates (which we subsequently found provided plenty of control authority) and after a bit of fiddling to get everything set up, we got the plane airborne. It tracked well on the ground and flew well from the off, but as can be seen from the video, a strange sound developed after a couple of minutes and a landing was called. Investigations found that the screws attaching the motor to the mount as well as the firewall attachment screws had come loose and the motor was flopping around in the cowl. I remembered then that I had only temporarily mounted the motor some time back to do some setting up and forgot that I had to tighten everything up and add the two remaining mounting screws.

After some remedial work, another flight was called and Prez soon had her flying graceful circuits and even a couple of loops. After about 5 mins I asked him to fly another loop while I filmed, but she seemed to have trouble gaining height. Initially he thought that the battery was running down, but upon landing we found the battery was still holding 75% charge when I noticed that the TE of the wing had ridden up over the rear step. We also found that the battery bay was bit warm.

I asked him how he found it to fly and he said ‘It’s a beautiful plane to fly. It feels just like a genuine vintage old-timer’. Praise indeed. I must say that I was excited to see her finally in her element and acquit herself well.

I have a couple of things to do before the next flight:

• A new receiver
• Change the wing hold-down from rubber bands to bolts
• Drill some holes through the firewall to let some air in
• Loctite the motor attachment screws

As soon as I get all that sorted, I’ll be back down at the field. I might even have a go at flying it myself. Thanks again Jim on designing such a lovely model.

[Mark Kettle 1]

A great build thread Fredrum, I enjoyed it immensely. You'll enjoy flying your Jemima .

[Fredrum]

Thanks Mark. It's gonna be fun

[Fredrum]

The flying field is adjacent to a swamp which can be seen in the video on the previous page. The vegetation is 7-8 feet high and the field can't be used on the weekend if it rains during the week as the swamp overflows. This is now Jemima's permanent home

Some weeks ago, I was flying and the plane ditched in the swamp. On with the gumboots (Wellingtons to you) and an exploration of Amazonian proportions failed to locate the model. It started raining the next day and didn't give up for three weeks. By the time I was able to get back in, there was a massive amount of new undergrowth and an extended search was fruitless. It seems Jemima has become part of the local ecosystem.

I wasn't too cut up about losing the model (we scratch builders are a philosophical lot by necessity) but I would like to have used the gear in another plane. Oh well, onward and upward. My new one is almost ready for starting

[Jim Newberry - Nuviation Ltd.]

Sorry to hear about your mishap Fredrum! It's all part of the game but very annoying when it happens - especially after you made such a beautiful job of the model!

Jim.

[Phil 9]

that is sad. it was a beautiful build I hope you will share your next project with us

[Fredrum]

Thanks for the support guys. I lost my modelling mojo for a little while there, but it's back now and I'm enjoying planning my new project. It will be an OD(ish) re-imagining of Boddington's Tyro Major. Will share as it happens.

[onetenor]

Going back to your question re retaining the tip if you make them knock off on a polyhedral job.Use the box and tongue method with hard balsa pegs through box and tongue. The peg breaks in a hard arrival allowing the tip to slip off .You will find the method in pictures on old plans and articles in old Aeromodeller and model aircraft magazines.

[onetenor]

Going back to your question re retaining the tip if you make them knock off on a polyhedral job.Use the box and tongue method with hard balsa pegs through box and tongue. The peg breaks in a hard arrival allowing the tip to slip off .You will find the method in pictures on old plans and articles in old Aeromodeller and model aircraft magazines.

[Former Member]

[This posting has been removed]

[Fredrum]

That's certainly a nice looking plane Percy. The classics never go out of style.

My plane will be bit more re-imagined than that. I'm turning it into a parasol wing open cockpit plane with turtle deck. If fact, you'll probably need a lot of imagination see the resemblance by the time I've finished. Watch this space.

Thanks Onetenor. That's very useful information to have.

[Former Member]

[This posting has been removed]