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Author Topic: Basic Trainer T/A  (Read 713 times)
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bushleague
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« on: May 21, 2013, 09:52:49 PM »

I got a notice I'd be kicked off the form if I didn't post something soon - sounds like publish or perish! Well I do like to publish when time permits so a few photos and comments on 1/2 A trainers is as good a place as any to start. Many years ago I decided I wanted make my .40 to .60 powered control line stunt models take-apart. I did some smaller models first to develop techniques and make sure they would stay together in the air. The photos are my take-apart versions of Brodak's .049 Basic Trainer.

For most training purposes its best to build these models in "one piece". Make sure they are air worthy, but don't spend much time on the finish. I took extra care covering and trimming mine because I sell the kits on eBay and wanted nice photos for marketing tools. Both models have been flown many times. The red, white and black one has over 150 flights on it and dozens of those were actual training flights. If built with some front end and wing joint reinforcement and flown over thick grass, crashes seldom cause any damage.

Many of the Brodak 1/2 A kits include a plastic engine mount compatible with the Cox .049 (Baby Bee, Black Widow, Golden Bee and Texaco engines with attached metal tanks). The mount is sold separately and can be adapted to most any 1/2 A profile model. You can install an engine with optional landing gear on one mount to create a "power pod" that can be quickly switched among several airframes. Multiple mounts can also be set up to try different engines on the same model.

Brodak has brought back many of the "solid wood" Goldberg 1/2 A models and Sig still offers the Dewey Bird and .049 size Skyray. All make excellent trainers and most have limited aerobatic capability. These models are really just 6 to 12 pieces of balsa with some plywood where strength is needed. The kits do save time, since parts are machined and die cut (or laser cut) and some hardware and decals are included. One could easily scratch build such models with wood and other supplies from the local hobby shop. I did just that with a few "original" designs made mostly from 1/8" cardboard, but that's for another post. Later...  Ed Prohaska
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flyingagin
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« Reply #1 on: May 22, 2013, 09:09:09 PM »

I like how you did that.
 Can you show how you make a larger take apart, like in the .40 or .50 size.
I am planing a 50" St .51 stunter, but it has to be take apart.

Ken
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bushleague
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« Reply #2 on: May 31, 2013, 02:46:04 AM »

I've done 5 larger take-apart control line models (4 ARF Noblers and one ARF Score). Details have been extensively published on the ARF board of the stunt hangar forum. The photo gallery of that form has approx. 50 pictures of the Noblers in various stages of construction. Here is a link to the gallery:

http://stunthanger.com/smf/index.php?PHPSESSID=redp5onagb0goqle60adv22dc1&action=gallery;cat=22

I attached some photos of the 4th Nobler which was finished about a year ago. It can be disassembled to the extent that all parts fit back into the box it originally came in. This will come in handy if the need ever arises for long term storage. If I decide to sell it, shipping will be much easier and less expensive.

Take-apart features do add weight, but there are also many advantages. I have access to nearly all control system components and can change the sensitivity and ratio of flap to elevator travel. Flight trimming is much easier. Components can be inspected for wear and serviced as needed. Its also easier to add color trim and decals to the separate parts vs. a one piece model. That would be especially true if the finish was paint instead of Monokote (the cowl and some internal areas are painted).

When I decided to make these models take-apart, safety was an overriding concern. It must stay together in the air. The first Nobler was heavy at 51.5 ounces, but flies well with a strong .40 or mild .46 stunt engine (currently flying with a Stalker .46 RE which is a little "too much"). Two have flown with FP .35s and .40s which worked fine (those Noblers are several ounces lighter than the first one). I switched them last season to the LA .46 because it has just a little more power and gives a good "stunt run" in essentially stock mode.

Unfortunately the Score ended up very heavy at 80 ounces (a 5 pounder). In spite of the weight it flies surprisingly well with a strong engine (ST .60) and in good conditions (wind 5 to 15 mph and little to no turbulence). A fellow with a camera mounted on a UAV made a video of it flying last spring and posted it on U-tube. Here is a link to the video: http://www.youtube.com/watch?v=0l5dCj8KWGY

A few seconds of the video includes ground shots of another club member flying an ARF SV-11, but the UAV shots are me flying the Score. Line tension is "robust" but manageable. The thick wing and fat fuselage create a lot of drag, so the model does not build up excessive speed in maneuvers. Later  ... Ed Prohaska 
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