Novice Trainer-ish model - RC Groups
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Jan 28, 2018, 02:52 PM
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Captain Dunsel's Avatar
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Novice Trainer-ish model


After finishing the Cherokee shown in another thread, I tried going to more foam and almost no wood. The Sassy 360 (the model shown in the end of the Learning Project Cherokee thread) worked out well, but still has a few drawbacks (especially in its fragile skin and rough appearance). So, I kept reading threads and kept experimenting.

One experiment was in covering a test core (same airfoil as the Sassy 360) with Dollar Tree brown wrapping paper and thinned Titebond….WOW! I was amazed at how strong, yet light the result was. And, after a top coat of thinned Titebond, followed by a coat of Polycrylic, it was completely protected against Krylon spray paint! I also covered a dummy horizontal stab with plain newspaper (the Sunday Comics) and the same Titebond mix. It, also, was incredibly rigid, yet light (well, it's incredible to this life-long balsa basher!).

So, I took the Sassy 360 and modified it into a high-wing, trainer-ish design, the Novice. My plan is to cut the model from pink foam and cover the wing with brown paper; the rest will be covered with newspaper.

I cut the fuse sides from a piece of 1” foam, then sliced the blank into the two sides. After that, I used a Dremel plunge router to route the foam to 1/4” thick.

So far, all flying surfaces (except the rudder) have been sanded and received their primer coats of Titebond/water (~50/50). I'm holding on doing the rudder until the fuse is shaped, as the bottom of the rudder is to fair into the fuse.

Several bulkhead, etc., sub assemblies are drying (I use aliphatic -- being retired, there's no reason to rush). Tomorrow, I hope to get the bulkheads glued to the fuse side (Gorilla Glue), and put a layer of newspaper on the aileron bay face.

CD
Last edited by Captain Dunsel; Feb 10, 2018 at 08:23 AM.
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Jan 30, 2018, 05:24 PM
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Captain Dunsel's Avatar
Busy day, but I got the bulkheads glued to one side (Gorilla Glue for wood-to-foam and Titebond for foam-to-foam), plus soldered up a few ESCs (I need one for this model, but why not solder up all the extras?).

Tomorrow, the target is to paper the tail feathers & ailerons, then brown-paper the wings.

CD
Jan 31, 2018, 06:15 PM
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Captain Dunsel's Avatar
I found what appears to be blank newspaper at Walmart, sold in 22" sq. sheets. To avoid dealing with ink, I'm trying this stuff on the Novice. Walmart calls it "packing paper", but it looks, smells, and tears (with a grain) like blank newspaper.

Today, I got the elevators, vertical & horizontal stabs, ailerons, and aileron bay cut-outs covered with the blank paper and 50/50 Titebond 1/water. I'm not going to cover the rudder until I can fair the rudder bottom into the fuse

CD
Feb 02, 2018, 03:41 PM
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Ken Myers's Avatar
OMG! I didn't expect to find you here.

I've been working on a trainer plane design for my student pilots this upcoming season. I'm on the sixth iteration at the moment. I did get to test fly two of them before the 'weather' set in.

It is called the RUA 2-4-10. RUA, Really Ugly Airplane and 2-4-10 is two for $10, the price of the DTFB and a little plywood used in the construction of the airframes.

Specifications:
Type: Scratch-built Park Flyer Trainer
Skill Level: Beginner builder & Beginner flier
Construction: Adams Readi-Board foam board, plywood, piano/music wire, wooden dowel rod
Plan Form Wing Span: 58-1/2”
Wing Chord: 10-3/8”
Plan Form Wing Area: 578 sq.in. or 4 sq.ft.
Length: 45”
RTF weight: 30.9 oz. or 1.9 lb.
Area wing loading: 7.7 oz./sq.ft.
Wing cube loading factor: 3.8
Feb 03, 2018, 07:43 AM
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Captain Dunsel's Avatar
Hi, Ken

Yes, I'm getting more into foam. For one, I've had a nasty allergy to balsa dust for many years. But, foam doesn't bother me at all.

I know I'm still using foam as if I were building with balsa, but I am learning new techniques and trying to learn a new orientation (paradigm?) with foam.

Those trainers look effective (I note you named them "Ugly 4"), and are probably gentle, slow fliers -- much better for training than overweight, fast, 'trainers'. I also strongly agree with REM trainers instead of full house ones (at least for the first model). Slow models give the student more time to think about what he/she is doing, and REM lets them concentrate on turning, not how to turn.

The Novice is quite a bit smaller (288 in. sq.) and will probably come out around 24 oz. Actually, it's intended more as a relaxed flier for Micki and I to play with, not a real trainer. It's also going to be the testbed for some painting ideas I have -- I really am looking forwards to getting away from shrinkfilm.

Bill
Feb 06, 2018, 08:11 AM
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Between errands (who says retirees have time to get bored?), got a few things done.

1. Added wing dowel reinforcement plate, which lead to having to add a 1/16" birch ply doubler to the dowel bulkhead when the dowel bulkhead split.

2. Drilling and gluing the dowel lead to my realizing the bolt plate was too high, so I added another 1/8" plate below the lower half of the bolt plate and Dremeled out the old upper half.

3. Built up the aileron torque rods.

4. Added a top coat of thinned Titebond to the flying surfaces. Happily, there was no bubbling, etc.

5. Added a strip of filament tape under the wing center section. Yeah, I'm hedging my bets on the wing strength!

6. Updated the plans to reflect changes.

CD
Last edited by Captain Dunsel; Feb 06, 2018 at 08:19 AM.
Feb 08, 2018, 07:29 AM
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Captain Dunsel's Avatar
Glued on the HS Wednesday; Gorilla Glue and four toothpick (cocktail stick) bits as reinforcement. Today, the objective is to add the fin (VS); after that, the model comes off the Frankenjig.

CD
Feb 08, 2018, 02:57 PM
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Captain Dunsel's Avatar
Added the fin today. Not seen is a bit of toothpick between the fin and the HS. After the model comes off the Frankenjig, I'll glue some more toothpick bits into the fin from beneath the HS.

CD
Last edited by Captain Dunsel; Feb 10, 2018 at 08:24 AM. Reason: Too many o's in caption.
Feb 10, 2018, 08:37 AM
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Captain Dunsel's Avatar
Busy Friday!

Pushrod tubes installed
Aft fuse bottom sheeted with 1/4" foam slabs
Faired wing TE into turtledeck
LG bent, soldered, and oversized wheels soldered on
"Windshield" added
Hatch fit and assembled
Elevators joined and ply control horn Gorilla Glued in


Won't get much done today, as we're doing a public display for our local Animal Shelter at a new Pet Value store's grand opening. Otherwise, it would be time to install the hatch magnets, then start sanding.

Side note: One of my favorite sanding tools is a set of Popsicle stick sanders I make up every couple of years. I glue them, side-by-side, to a cut-down sheet of sandpaper, then glue another sheet on the top, Last, I cut them apart with a sacrificial razor knife. They work like a ladies' emery boards, but mine come in all grit sizes (including 80 grit -- I'd hate to see a human who'd need an emery board of that coarseness). Anyway, the sanding sticks are better for fine cutting foam than a knife, despite being a bit slower.

CD
Last edited by Captain Dunsel; Feb 10, 2018 at 09:09 AM.
Feb 12, 2018, 06:04 PM
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Captain Dunsel's Avatar
Between Sunday and today, got the fuse sanded, did a bunch of spackling, and started covering the fuse with blank newsprint.

I did make the happy discovery that the wheels I'm using have hubs that disassemble...of course, I didn't realize it until after I'd soldered washers on the axles! So, the washers are now off and the hubs taken apart. Once I get them painted, I'll reassemble them and carefully solder the washers back on.

I'm trying a different way to use hatch magnets. Usually, I have the magnets face to face, flat on the bottom of the hatch and top of the fuse. What I don't like is that it puts a lot of stress on the glue holding the magnets.

On this model, I've glued a doubler on the hatch's bottom and glued a pair of magnets to the sides of the doubler. The matching magnets are glued to the inside sides of the hatch opening. This way, the removal force is a shearing action, putting much less stress (I hope!) on the magnets. To help hold the magnets in, too, I'm papering them over with newsprint.



CD
Last edited by Captain Dunsel; Feb 12, 2018 at 06:15 PM.
Feb 14, 2018, 01:04 AM
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JabiruAbe's Avatar
Looks great!

I am planning to build something like that-inspired by a 40. glow trainer.
Feb 14, 2018, 09:06 AM
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Captain Dunsel's Avatar
Primed the fuse with coat of thinned Titebond, let it dry, then weighed it. 133 grams.

After that, I papered the fuse with Walmart packing paper (blank newsprint?) and thinned Titebond. When dry, the fuse weighed 150 grams, but is now pretty darned rigid. So, today I'm adding another coat of thinned Titebond, then it'll be time to prep for painting.

JabiruAbe, go for it! It's great fun to see your own creation fly!

CD
Feb 17, 2018, 03:37 PM
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Captain Dunsel's Avatar
Got the first coat of paint (Sherwin-Williams interior latex house paint) on the model this afternoon. It took me a bit to remember the right mix (2:1, paint to clear Windex).

CD


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