RCM&E at 60: Kakadu, the first free plan

[Dad_flyer]

Thank you. I am still thinking about the power. The plan says 0.6 to 0.8cc. The outline on the plan is a diesel, so the top end of that range is the PAW 049, which is 100W. I shall probably put in a relatively large motor as the little ones look wrong and I think I shall need the nose weight. Then prop for 75-85W maybe.

I shall also need glide tests.

I had not thought of that incidence as 'longitudinal dihedral'.

Edited By Dad_flyer on 12/04/2020 20:46:33

Edited By Dad_flyer on 12/04/2020 20:46:51

[Dad_flyer]

Joining the internal structure to the first side. Beginning to get somewhere now. I think it would have been easier if I had re-drawn the plan with sharp lines before starting. Taking everything off the one cut rib and the first cut fuselage side has taken more thought and more time.

I remembered to put in holes for the wires and two battery positions before joining the formers.

[Dad_flyer]

Second side joined on and seems to be straight. Tail peg in and supported by scraps, then the top and bottom spreaders.

[Dad_flyer]

It has been a while since I posted. I put the rear top sheeting on. The plan says longitudinal grain, which is unusual. Probably it would be fine as there are the internal braces, but I did cross grain anyway. The last part will need to be length ways because it needs to bend into the former for the dihedral v.

This has had a couple if coats of thinned dope and sanding. Next I shall put tissue on the sides, as that is easier without the pegs for the wing bands. Then the pegs go in and I can finish the sheeting.

[Dad_flyer]

I also had some off cuts of really nice soft balsa and messed about with bending. 1/16" making a chair (or air intake if you put it the other way round), 3/32" and 1/8" bent round a pencil.

I also got 1/16" to go round a small screwdriver, so made a cover for the push rod exit.

[Dad_flyer]

Slow progress here, I have jobs on five models going on. Put in the last piece of the top sheet.

Looks nice faired into the wing dihedral like that, but I think it also means that there is no locating surface for the wing position. I shall see how it feels with the wing covered. I can always add something under the wing to slot into the fuselage.

I planned a blue and white tissue finish. Of course the white has very little colour depth. In the above photo the sides are covered, the top is not. Are there any cunning ways to get it a bit more white without going full hog on paint?

[Dad_flyer]

Bottom done as well now.

[Dad_flyer]

I don't like making wire undercarriages. Well this is only the second, but bending correct angles in two planes is confusing and frustrating. A jig helps.

Dispite, or maybe because of, my dislike of doing it, I am inordinately proud of the end result.

Wheels from SLEC.

[Geoff S]

I find the actual soldering quite easy (well, I've been doing it on and off for about 70 years ) but getting the bends in the right place and allowing for wire thickness etc is, as you say quite tricky. You seem to have ended up with a more than satisfactory result anyway

Not my sort of model but there's a lot of satisfaction in creating a working model from a pile of wood rather than a kit as I've rediscovered these last 2 weeks.

Geoff

[Dad_flyer]

It is not the model I was wanting to build either. It was supposed to be Miss Deeds next, and I did not want a biplane, or a small plane. But then the anniversary came round and I wondered what plans they had at the beginning. I found the one from the first issue and then there was not really a choice but to build it. I do like vintage, so it does have that . And the more different things I attempt, the more I learn.

[Dad_flyer]

The plan has a lower cowl, with the upper part open for an upright engine. With a round electric motor I have made one more change than I was going to allow myself, and the cowl will go all the way round. Carefully removed the step from the sides with a nice sharp scalpel.

Both sides done, and the hatch in place. I still need to finish the hatch sides flush.

The cowl will be 1/8" curved all the way round. I hope .

[Dad_flyer]

I did firewall S1 in balsa as the actual motor mount needs to be further forward. Laminated 1/8" balsa and ply to hold 3mm T nuts. Side pieces set the 2deg down thrust and 1.5deg right thrust.

The battery slips in as planned (just). Three possible positions to help with the CG, this is the middle position, C.

B might not be possible (won't go under the T nuts). However a diagonal version of B will, if needed.

[Dad_flyer]

Made a 6" wide piece of 1/8 soft. Wetted and wrapped around for the cowl. The pegs for wing bands come in handy .

I hope I can work out how to cut a big circle in after for the motor. I thought it would be easier to cut when flat, but might then not bend well. I can always do another if this does not work.

[Dad_flyer]

Biting the bullet and cutting out the rear deck for the tail. I had put in pin marks from the plan when cutting out the sides.

Join the dots, and put in a second line at 1/8".

Then I cut out half way between. Lastly trimmed to the lower mark on the sides.

The pin marks are clearly there on both sides, so if things were cut straight and joined straight, this should be straight....

Time to check and sand.

[Dad_flyer]

As far as I can tell, it is level. .

[Dad_flyer]

Is all piano wire supposed to bend, or is some tempered differently? I have a piece of 16SWG which I have tried to use for two different things. Both required bends all the way back on itself. It is very stiff to start bending and then broke. Another piece of 16SWG was fine.

This is the second item to bend, the tail skid.

And trial fit

It is probably more weight than necessary for a skid, and at the wrong end of the model. I shall not glue it in before I have tested the balance.

[Bob Cotsford]

I've got some threaded pushrods which are particularly brittle and are impossible to bend, which makes them pretty much useless as pushrods. Sometimes the wire we can get does seem to have too much temper but more often it's like overcooked noodles. When I were a lad piano wire that we got seemed more predictable

[Dad_flyer]

So I need to sort the piano wire like selecting balsa soft, medium , hard .

[Dad_flyer]

Got round to putting the fairing back on for the tail last night.

Infill in the base first.

[Dad_flyer]

Time for the firewall. My slow Epoxy tubes are rather empty, so I did it by weight. Looking very picturesque.

[Dad_flyer]

The firewall and side pieces as above.

And glued in place.

[Dwain Dibley.]

Hello D.F.

Just read thru and thoroughly enjoyed your build. Very neat work and some nice subtle changes too.

If you don't want a heavy tail skid, just make 1/8th ply one.

Keep up the good work.

D.D.

[Dad_flyer]

Thanks DD. I have been following your Mr Mulligan. I am so much slower on this build than you are! I need to crack on to get it finished in anniversary May.

I did a quick balance check with motor but no battery and it was nose heavy, I think that was with the skid in. Anyway the battery servo etc are all in front of CG. We shall see what happens with covered wings.

[Dad_flyer]

With the motor fitted, a piece of cardboard fitted for the hole in the cowl.

A circle on a curved plane makes an oval.

Then transfer this to the formed balsa cowl.

Who can spot the mistake?

[Dad_flyer]

Whilst you ponder my embarrassing error, I have also tested the power. E-calc said that this motor (1000kv) on 2s (mid charge) with a 9x6 should give 5900rpm at 55W and 440g thrust. AUW looks to be a little under 1lb, so that would be ok. Well below the motor rating, but it is a motor I had and ground clearance is only enough for a 9" prop. As long as the reality is not too far off this prediction...

I did not put the power meter on as it is all so far below battery, ESC and motor spec. Got 5900rpm on a storage charge battery, just as calculated, so that is good .