Ken Willard Schoolboy for Ponte 2023

[leccyflyer]

Started putting together the kit of balsa bits that I cut the other day for a Ken Willard Schoolboy. I was looking for a quick build, to be able to take part in the spirit of the event. It'll proceed alongside my main project, which is to successfully fly a KK Outlaw single channel fifty years since my last attempt.

The ribs were cut out and finished with a couple of thin ply templates in the good old fashioned sandwich method. The other bits were cut with their outlines transferred from the plan with Frisket film. A small order from Balsa Cabin, arrived yesterday, containing the trailing edge stock which I was missing, I had some stocks of well seasoned 1/16th sheet which came from the sale of a clubmate's modelling goods after he had passed away a few years ago. That, plus the scraps box, has provided the kit of parts and it was a nice change to get back to cutting balsa.

I also 3D printed a couple of the ingenious dummy Cox engine mounts, which house a tiny brushless motor. I couldn't believe that the model would fly on the 1106 motor that fits the dummy Cox .010 , with a 3 inch prop and the article describes how Ken Willard had flown the Schoolboy with a Cox .020 initially, so I printed one of those as well, to take a 1306 motor, which will turn a 5x3 prop. The only deviation so far is that I slightly enlarged the motor mounting plate so that it would allow either motor to be fitted.

The basic framing of the wings is done, I built them separately, rather than in one piece then cut in half, due to that fitting better on my small building board. I'll join them at the correct dihedral angle and sheet the centre section tomorrow, then make a start on the fuselage.

[Small-RCer]

Am planning to build one to meet the under 250g limit with a helicopter version of a Cox 020 and Rudder Elevator. I see you kept the original airfoil. Are you reducing the angle of attack? I was thinking semi-symmetrical airfoil and only about 1-2 degrees AOA.

[leccyflyer]

I'm building to the downloaded plan. The only modification I've made is to add a few mm to the motor mounting plate, so that I can fit the .020 dummy and 1306 motor if necessary. By all accounts though the model flies beautifully on the modest amount of power available with the .010 set up- 1106 motor, 3x2" prop.

Mine will have two servos, to give the option of using elevator at least for the initial test flights.

[leccyflyer]

Making progress. Should have the framing out finished today and have started covering - Doculam first, then will be tissue with Eze-Dope over that .

It's been a nice simple build, notwithstanding the Schoolboy error of making two left sides - not the first time I've done that and surely won't be the last, but easily remedied.

[Tobe]

....could have been that it was trying to tell you to build 2!

[leccyflyer]

A pal of mine made that mistake years ago, told himself just that, to just build two, then promptly built a third left side!

It's been a long time since I've built from a plan, really enjoying it and it's got the memories flooding back.

[Spike S]

Two Left sides ? It's all too easy to do the same when hot wire cutting tapered foam wings !!
Easy to convince yourself that it's all good practice and the second (and third ) ones are for mates.

[leccyflyer]

I'm at the covering stage now and had intended to just go with Doculam straight onto the bare balsa, but old habits die hard and in my previous life of tissue and dope, I always gave the airframe a coat of sanding sealer and a light final sanding before covering. I succumbed to a thin coat of sanding sealer and some light sanding on the wing, together with final fuselage shaping, after adding the hatch and battery supporting plate, wing is now ready for covering and the fuselage has just had a coat of sanding sealer and will dry out this evening.

Couple of piccies of the servo install - a Kavan microservo for the rudder and a (possibly temporary) Saturn Pico servo for the elevator, at least for the trimming flights -the Cox dummy engine motor mount, at TD .010 size for the 1106 motor and 3x2.5" prop and the fuselage taped together to get it's picture taken.

I'll never learn - I usually just say I'll do a tiny bit of sanding before putting a mask on, then half an hour later I'm covered in balsa dust and coughing. At least the sanding sealer dust smells nice.

[leccyflyer]

After a thorough sanding of the entire airframe the 42 micron matt laminating film went on mostly fine - a few saggy wrinkles that wouldn't shrink out at the wing open structure to sheeted section underside join, but not too bad. Fuselage was a piece of cake.

Then moved onto the tissue, which was tremendously relaxing. It's coming up to thirty years since I last did any coloured tissue and the first time over laminating film. The Deluxe Materials Eze-Tissue is relatively heavyweight, but we'll see how it works out. The film covered wing weighed 42g before application of the tissue. I applied it wet, soaking in a 5% solution of Eze Dope, then wringing it out, before applying to the wing. From a video I saw online application consists of dabbing a 25% solution of Eze Dope through the tissue with a small piece of sponge, then teasing out any wrinkles with the fingers for a smooth surface. Underside first, one panel at a time then left to dry.

Once dry, I trimmed back the tissue on the wing and set to on the top surface. Checked the wing out at various stage to see that it was still straight and all looks fine. In the meantime I started covering the fuselage in red Eze Tissue, which again went on very well -easier than the wing. Also did the tail surfaces.

As it stands I just need to complete the fuselage top surface covering -before I put another coat of Eze dope on everything - or possibly a couple of coats. I'm shooting for a matt finish for this one and don't want to build in unnecessary weight.

[leccyflyer]

Schoolboy is all done, balanced and checked out, but it's pouring down here, so no chance of a test flight before the event, so it looks like I won't be flying this one after all.

I was surprised quite how much waft the wee 1106 motor and 2.5" prop generates - should be interesting.