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Jul 14, 2019, 02:55 PM
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grossiman's Avatar
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Build Log

Conversion of an old 2-axle trainer to electric drives and four-flap wings.


Hello.

If interested, I would like to start here a small conversion report. The model has already been completely rebuilt, I would like to use this Thrad as a suggestion. There are certainly many models in your home where a conversion is worthwhile.

Now for my remodeling,
It is my first motor model, a Westerly 2-axle trainer who had not left the attic for more than 15 years.
And that's the good piece, the Westerly had to put up with a conversion to biped gear. Also, the hood is not original, that's a pretty heavy one
Fiberglass-made.

Before I disassembled the Westerly, he was weighed. Without fuel, receiver battery and receiver he has brought 1817g on the scales, of which the area alone weighs 369g. I recall that he weighed just over 2100g at the time.
However, I would like to undercut this weight, this should be feasible.

Let's start with the bonnet, my first self-made GFK part in positive construction, proud 88g. Even my self-built biped chassis, too robust and too heavy, 228g with wheels.



Greetings Andreas
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Jul 15, 2019, 02:17 PM
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Hello.

After I had freed the fuselage from the old stringing weighed the pure shell abdomen 456g. So I started to make the hull easier. First, the tail was the turn, this consisted of a 6mm hard balsa. From this I have made a stabilizer in stick construction, and also the oars I have relieved a bit. Also in the fuselage in the tail area relief openings have come in.
Then I made the Accumulator from poplar plywood, with many holes inside. It should not weigh too much, my goal was to stay under 2Kg takeoff weight. And that's why the hull was also perforated. The motor holder for the brushless motor I built from 4mm plywood.

Greetings Andreas
Jul 16, 2019, 03:58 PM
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Hello.

So, go a little further.

On the underside of the fuselage, an access hatch for the ESC has come in the front part. And a little further back an air outlet, this is used for cooling the ESC. The air intake comes later in the hood. The battery door is simply secured with a rubber band on the wing dowels. Then I made the chassis new, it consists of 4mm and 3mm steel wire. I reinforced the fuselage with 4mm plywood in the suspension area. I roughened and cleaned the two suspension wires at the connection points, and then wrapped and soldered the parts of the vehicle with a thin winding wire. The old wheels with the rubber tires I exchanged for light wheels with foam rubber. Before, the main chassis weighed only 228g (8,04oz), now it weighs completely with rear wheel 117g (4,13oz).

In the next post, it continues with the conversion of the wing.

Greetings Andreas
Jul 17, 2019, 11:33 AM
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Hello.

Round 4.

Next, the wing has been rebuilt, it was already a bit hurt to disassemble an intact wing. But hey, it should be retrofitted ailerons and flaps.
Because the V-shape of the wing was quite large for aileron operation, the wing was split. I carefully cut out the old surface connector with an iron saw blade. Also, the planking on the inner wing and the first three ribs were removed. Fortunately I still had the blueprint, so it was not a problem to make new ribs. Where later the Sevos for the ailerons and flaps should go, I also planked the wing, but only the underside. The area of ​​the end bar was also planked, where I sawed out the ailerons and flaps later. The interfaces were then sealed with balsholz. Then I prepared the mounts for the Sevos, sawed out the ailerons and flaps. I also redesigned the marginal arches, the old marginal arches made of plastic have become brittle over the years. It continued with the completion of the ailerons and flaps, which I have built as slit flaps. The hinges for this I have made of plywood itself. Then the wing halves were glued together again, but this time with only 1 V-shape per side. Then all I had to do was solder the servo cables and glue the rest of the planking. Now only the bonnet is missing, but this in the next post .

Greetings Andreas
Jul 21, 2019, 03:14 PM
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Hello.

Final sprint.

Next I installed the engine. I decided for a Joker 4250-6 from Planet Hobby. The battery should be a 4S, and a 12x6 propeller. For testing I had used a Turnigy K-Force 100A. Meanwhile, a Graupner 100A + T does its job in the model. A smaller ESC would have done it, but I still had that ESC. Now the servos for the elevator and rudder were missing. I have these installed at the rear of the tail. As it turned out later that was a mistake, but more on that later. After I had installed all the components on a trial basis, the model was covered. The rebuilt Westerly also got a name addition, I call it now "Westerly.mod". Then I put everything back in, and then the model had to be on the CG scale. And now revenge that I have installed the servos for the elevator and rudder rear, I have not managed to adjust only by moving the flight battery the CG. I did not want to install lead at the front, then I would have come over 2Kg takeoff weight. But I really wanted to stay under 2kg, so I put the engine ahead and extended the cowling. So, now fit the CG, but the front looked almost like a Pilatus Porter, it was missing only the exhaust dummies of the turbine. But I did not feel like doing that anymore, I just put a sticker on it.

To the flight characteristics:

I do not know if you always feel that way, but if I have a new model, or as in this case a completely rebuilt model, then I always have soft knees on the Maiden, and I've been flying model airplanes for several years. So off to the model airfield, model ready made, rudder check, model against the wind and (with soft knees) pushed the throttle. After 7-8m the model was in the air and rose with 45 in the sky. Conclusion: performance is more than adequate. Since the wing profile has remained the same, I have taken over the old CG, it just had to trim the elevator a bit. The retrofitted ailerons work perfectly, and the lower V-shape has not been detrimental, on the contrary. After a few familiarization rounds, I then tested the flaps. They also work noticeably. If I were to make such a conversion again, I would have made the ailerons a little smaller and the flaps slightly larger, about 50:50. Now they are ailerons60: Flaps40. At full throttle, I can climb vertically with the model, and only to hold altitude is enough if I operate the motor with 6-7A current consumption, with set flaps even with only 5-6A current consumption. With a 4S 3000 Lipo I can fly well over 20 minutes. Aerobatics is due to the wing profile (straight bottom) only conditionally, that may not fly inverted. But a loop, a barrel roll or slipping is feasible. The most fun is to make a slow flyby or steep landing approaches with set flaps. The model weighs with the 4S 3000 Lipo 1910g, which compensates somewhat for the too long muzzle. the drive provides with a APC 12x6 with full battery a thrust of 2800g. Since only one helps, the model needs a towing clutch, somehow you have to use the excess engine power.

Greetings Andreas

Maybe someday I'll be able to make a video.
Jul 22, 2019, 03:42 AM
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That is very impressive.
Well done.
Jul 22, 2019, 02:17 PM
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grossiman's Avatar
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Thank you for the praise.

Greetings Andreas
Jul 25, 2019, 09:44 AM
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You did better with English than I would do with German language that I learned in high school classes.
Jul 26, 2019, 10:09 AM
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grossiman's Avatar
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Hello E-Challenged.

Since I have to disappoint you, I was too lazy to learn English at school, of course, today I am annoyed about it. What you read here, the praise belongs to the Google translator.

Greetings Andreas


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