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Old Mar 20, 2016, 11:58 PM
Keith Shergold is offline
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Build Log
Dumas 35" Tiger Moth

Hi guys, I'm new here. I've decided to get into model planes again after a 12-year hiatus, and I've decided to build this Tiger Moth as a way to get re-acquainted.

In the interest of full disclosure, I built a peanut-scale Gypsy Moth last year with Plantraco actuators, but its flight performance up till now is something I'd rather not discuss, and this larger model is a more sensible re-entry to the hobby. I haven't given up on the Gypsy, it actually did fly, just not reliably because I didn't build enough wash-out in the wings so steering it was a little annoying. I will re-visit that model when I've got a little more experience.

Anyway, I've made a start on the Tiger Moth. So far I am pretty pleased with the kit. I snapped all the wood that was provided to bend and laminate the tail outlines, but I ordered some new balsa strips and they worked out fine. Halfway through building the wings, I was seized by a desire for ailerons, so I am going to modify the lower wings with a trailing spar that can support them. I think since the kit was designed, radios and batteries and servos have gotten lighter, so I may be able to include an aileron channel without too great a weight penalty.

I am going to cover the plane with tissue, because I'm a purist at heart, and the look I am going for is more along the lines of an old fashioned rubber-powered model than an actual scale model.

I've decided to leave the designed amount of dihedral in the plane, so I am expecting that it will still be for all intents and purposes a three-channel model, with the ailerons giving it the ability to sideslip if I want it to. I understand that this is basically how a real Tiger Moth handles, so we'll see how it works out.

I find a lot of my balsa-and-tissue muscle memory is still there. I am a little lost when it comes to the selection of power and radio gear, but I have some advice from Pat Tritle I have decided to follow, and with a bit of beginner's luck, I'm hoping this model will be successful. I'm really enjoying the basic wood work.

Here is a picture of the fuselage, upper wings and horizontal tail:
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Old Mar 22, 2016, 09:18 AM
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Here is the framework with landing gear. The landing gear was a little difficult to solder up, but I got it in the end. Still have to build the ailerons and devise a way to mount them. I'm planning on driving them with a single servo in the middle with some of that cable-in-a-tube stuff. Although I have batted around the idea of making small bell cranks in the wings to give the ailerons a bit of differential movement, like the real Tiger Moth. I still have time to make up my mind as the silver tissue has not arrived in the post yet.
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Old Mar 22, 2016, 01:32 PM
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Quote:
Originally Posted by Keith Shergold View Post
Here is the framework with landing gear. The landing gear was a little difficult to solder up, but I got it in the end. Still have to build the ailerons and devise a way to mount them. I'm planning on driving them with a single servo in the middle with some of that cable-in-a-tube stuff. Although I have batted around the idea of making small bell cranks in the wings to give the ailerons a bit of differential movement, like the real Tiger Moth. I still have time to make up my mind as the silver tissue has not arrived in the post yet.
Hi Keith,
Looks great and welcome to RCG!

So nice to see someone building wood

John
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Old Mar 23, 2016, 12:36 AM
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Thanks John!

Well I just got the silver tissue in the post, as well as a few other colours. I haven't really decided on a colour scheme yet, probably all-over silver, or else silver flying surfaces with either red or yellow fuselage: I can't really make up my mind; I might have to flip a coin or ask my wife what she thinks.

Anyway i have quite a bit of sanding and aileron-building to do before I make up my mind. The tissue is pretty though. The Easy-Built tissue seems to have nice vibrant colour to it.
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Old Apr 01, 2016, 10:56 AM
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Well, the colour scheme has modified itself. The silver was a disaster. I was hoping that since it was "real" aeroplane tissue paper and not just Wal-Mart stuff, the silver paper would be easy to use. It's not. The silver coating gives it sort of a plastic-y surface, which looks very nice, but I've always had to use a different covering method with it: I spray it with 50/50 water and alcohol BEFORE putting it on the frames, then I pat it dry with a towel. This makes it evenly wet: otherwise the silver stuff just makes the water bead and form wet pockets. Anyway, the training edges are too frail on this plane to cover it that way. By the time I got a nice covering, to my horror I discovered it had pulled the trailing edges of the wings into a wavy mess. Also, any little wrinkle shows up twice as bad with the silver.

SO, I went to plan "B". Plan "B" involves finishing the machine in an old-fashioned "rubber powered free flight" look. I had some "linen" coloured tissue, so I used that on the wings. This tissue behaved itself a little better on the floppy trailing edge, and I managed to get it more or less straight, with washout and all. . I'll use red on the fuselage and tail. Even with the utmost care the second time around, I see the tissue has bowed the 1/16 top spars on the wings. Oh well. I am sure it will fly. Up close, a real Tiger Moth looks a little round around the edges, too.

I had forgotten how much craftsmanship and experience is needed to do a really good tissue job. I am not particularly proud of this one so far, but on the other hand it is reasonably warp-free so far and looks OK. I photographed my work so far in the harsh sunlight so I can't be accused of trying to hide mistakes with clever photography.

I actually like the look of a transparent-ish tissue covering, so rather than try to make this model look like a "real" tiger moth, I am going to try and capture the look of a rubber-powered model from the 50s, except this one will be radio-controlled.

Oh and the motor and servos arrived today in the post. I'll be darned if I can settle on a way to actuate the ailerons, I guess that's today's job as well as mounting servos and covering the fuselage if I feel lucky.
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Old Apr 02, 2016, 11:35 AM
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Looks great from here Keith! I've never worked with tissue but I love the look.

Please tell me you're not going to use that APC prop on it! Ditch that and get some GWS SF or HD props.
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Old Apr 02, 2016, 12:18 PM
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Thanks! I haven't done a proper tissue job in decades, and it's pretty obvious close up. This is a very delicate structure, and it's very difficult to control the rates at which different parts of a piece of skin will shrink. It looks OK but is far from my best work. Also it's almost impossible to get nitrate dope so I've had to use butyrate, which is a bit inferior in this application- the skin is a bit rubbery, and paint won't stick to it so all the colour has to come from the tissue itself.

Still, I am pleased with the look. I think it will be a nice model if I don't screw it up .

It turns out I am not going to be using that prop- I ordered a 8x3.8 slow-flyer prop yesterday, but it is still an APC prop. Is this still not a good choice? I can order some GWS ones, if they are better. Are the APC ones inferior? I would love some advice in this area- I don't know much about powering these things. Back when I started building electric powered models, the kits always came with a prop, usually a motor too. Now they don't. It's frustrating.

Also, I have a question about servos. I have some very small Blue Arrow super-sub-micro servos for the ailerons. They have a different plug on them than the spectrum plug that is on the other slightly larger elevator and rudder servos. Is it OK to swap the plugs and use them, or does the different plug mean the servo itself is incompatible with the radio? I can't see why it wouldn't work, but I'd like to find out before I encapsulate the servos in the wings!
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Old Apr 02, 2016, 07:00 PM
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The GWS props are lighter and unload a bit more in the air, they also fit the built-in prop saver on your motor. The servo should work fine with a change of plugs. I like the E-Flite stuff, except for the prices. I've switched to nearly all my power setups from Headsup Hobby, great prices, motor performance specs with a variety of props and $2.50 flat rate shipping! Good people too.
http://www.headsuphobby.com/

BTW, there's a member selling 5 packs of GWS 8x4.3 SF props for $4 shipped right now in the classifieds here:
http://www.rcgroups.com/forums/showthread.php?t=2636057
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Old Apr 02, 2016, 07:58 PM
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Hey thanks!

I worked on the plane a bit more today; got the elevator and rudder servo rails and pushrod guide tubes fitted so now I can cover. The pushrods are in there too, but pulled all the way forward so I can put the tissue on there and don't have to handle the fuselage too much to get them in there later.

I also put together the engine cowl, I was nervous about this because there is one way to mess up he appearance of a model- badly-fitting plastic bits. However I was pleasantly surprised that some good advice from Pat Tritle in the plans book, and a methodical approach and I've got a nice well-fitting cowl now. I am making a pot of tea, and then I will get busy on the fuselage covering. The Easy-built tissue is a nice bright red so I'm hoping this will look rather nice.
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Old Apr 02, 2016, 08:07 PM
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If you google the Tiger Moth and look at the images, the cowls don't fit that well.

I am working on a HK Tiger Moth. Doing the covering as I feel like doing it, slowly.

I have the fuselage done and all the servos in and working. Landing gear is fitted and
finished.

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Old Apr 03, 2016, 01:56 AM
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Nice. You can't beat a yellow Moth. I really gave some serious though to doing mine in yellow, but I wanted to colour the plane with the tissue, and I recall from when I was a kid, the yellow tissue loses its colour the fastest as it ages. I had a yellow rubber-powered Fairchild 24 that lived long enough to turn almost transparent.

I did notice the cowls on real Tiger Moths don't look like they fit all that great. I think when they inverted the engine they had to make the cowl fit kinda loose to allow cooling air to flow through. To be honest I find the "Gypsy Moth" to be a much more attractive aeroplane for that reason. I'm tossing around the idea of doing another one of these, and converting it to a Gypsy. It'd be neat to have one of each.

Anyway, I think I did OK on my model's cowl, meaning it doesn't seem any more ill-fitting than a real one, and I've done the fuselage covering. It turned out OK... I should have put some gussets on the bottom bay just behind the wings, but hey that's why I'm building this plane, to re-learn how to do it.

I'm colouring the wing struts with tissue, too. I thought about maybe painting the wings silver, since the silver tissue didn't work out, but my wife says she likes that the wing structure is visible, so it will stay the way it is. I think it looks kind of neat in a minimalist sort of way.
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Old Apr 03, 2016, 03:07 AM
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Very nice work. I do some tissue as well.

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Old Apr 03, 2016, 07:13 AM
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That looks fantastic Keith! The cowl is a nice fit, is it one piece?
Your tissue looks excellent from here and your tail feathers are nice and straight. How did your hinge them?
Those cabanes look like they were a chore!

Keep up the good work!

Jim
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Old Apr 03, 2016, 09:19 AM
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I didn't do a very good job hinging them, I'm afraid. The kit comes with some squares of this plastic stuff with a fuzzy coating. Problem is, I didn't read the plans carefully enough and my elevator now only has two of the suggested five hinges. Therefor closer to completion I'm going to make some sewn hinges like one would do on a free-flight model. Next time I will buy some actual hinges. And pay closer attention to the plans. And use a bit less glue.

I've just noticed the right horizontal stab has the tiniest twist in it. It was perfectly flat before so I guess that's what these planes do. A session with the kettle once it's all put together before the final coat of dope and the rigging wires and things go on there and it will be fine I'm sure.

The tissue job, close up, is "acceptable". On the wings where the trailing edges join the wingtip bows there is a very fine butt-joint, and so the tissue has pulled the back of the wingtips up a bit, resulting in a bit of an upward flare, and a couple of puckers in the tissue right where the joint is. If I was wiser I would have put a gusset on there. I am not going to fix it, however, as it isn't noticeable from two feet away and fussing with tissue, I've learned, can sometimes make things a lot worse. I feel tissue is a "master" level covering technique, and I'm just happy that it looks decent from a few feet away.

The cabanes and landing gear were challenging (as if the whole plane isn't challenging): I've never soldered steel before, for one thing, and getting all the little pieces to hold still for it was an interesting exercise in patience. I drilled little holes in a block of wood to hold them still. The worst was the landing gear, where several bits come together at the same spot. I got it in the end, but not without some colourful language.

Actually the whole plane has been steeped in colourful language.
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Old Apr 04, 2016, 06:53 AM
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I've been using a very fine gauge copper wire (bought in a spool from Harbor Freight IIRC) whenever I have to join music wires for landing gear for soldering. It may be a tiny bit heavier but is so much easier, and may be a bit stronger in the long run.

I have a Dumas Nieuport 28 on the way (another one of Pat's designs) so I'm enjoying your build and appreciating your pains along the way. But I'll be using Coverlite, tissue seems too daunting!
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