Another hare-brained idea

batjac Fri Jan 31, 2014 1:53 am

Well, a few months ago when I was over at Delta Park and flew Duke's e-Beginner's Ringmaster, I told him I had an idea that I thought I'd follow up sometime for an electric C/L setup. I've seen the guys using the R/C car transmitters as control handles, or using aircraft transmitters from their neck or strapped to their body. Or, if you really want to spend some bucks, there are a couple of expensive commercial electric handles. But I figured I'd make my own cheapie electric handle. So, I started a couple of days ago on one. As usual, I jumped in without taking pictures at the start. I started with a spare 4 channel transmitter that I got with a Blade MCX. Anyone who's bought the Blade micro copters and bound them to their Spektrum radio has a couple of these around, so it seemed like a good start. For Y'all who don't have one, here's what the stock Blade transmitter looks like:

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So, after removing the board from the case and stripping off all the unnecessary stuff, here's what's left:

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To power it, I'll use this 500mAh battery and a step-up regulator that I got from the Hobby King USA Warehouse last year to use on 1/2A R/C planes.

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The receiver will be a cheap DSM2 receiver I got from Value Hobby last year for 8 bucks.

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First I measured out the position of the applicable controls and cut out slots/holes for them in a piece of 1/32 ply, and glued in four pieces of 3/32 bass dowel for the circuit board. I only made slots for the throttle channel and the power switch, holes for throttle trim, power light, and the right stick in the neutral position. It still has the other three channels available, so If i need them I can cut slots out for them at a later date.

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I glued on some side panels, then cut a back panel out of another piece of 3/32 ply.

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Test fitting the board in the case.

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I plugged in the battery and turned the transmitter on. The transmitter beeped twice and the light came on. With everything looking good, I closed it all up and installed the battery.

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Looking good. So I hooked up a servo to the throttle channel to test the transmitter for proper operation.

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But, not so good. I had thought I'd bound the transmitter and receiver previously, but no joy. In fact, the transmitter wouldn't bind at all. It just kept beeping rapidly at me. So, I disassembled it all and tried again. Still the same, so I push and pulled and prodded, and the beeping stopped when I pushed the switch for low rates. So, I bound the transmitter to the receiver before closing it all up again. It worked, so I closed everything up and tried again. This time the servo tracked with the throttle stick.

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Tomorrow I'll work on the mounting scheme. I'll make a mount and a control handle for the box to attach to, and also make some kind of attachment point so that I can strap the box to my leg if I want to use a standard handle.

The Hare-Brained Mark

duke.johnson Fri Jan 31, 2014 10:09 am

I'm watching this one Mark. Keep up the good work.

pkrankow Fri Jan 31, 2014 10:27 am

I think I may have missed or misread something...why not use the original case and strap it down?

Does throttle hold position? If it doesn't then you need to hold the throttle position the entire time.

A cheap spread spectrum car transmitter/receiver seems in the same $$ ballpark as where you are going.

I assume you are going to build a full function scale bird, or a carrier plane, with this.

How do you plan to finish the case, black paint or poly varnish?

Phil

**RknRusty** Fri Jan 31, 2014 10:40 am

Hair Brained, maybe. But creative for sure. And obviously spare time on your hands too. lol!

batjac Fri Jan 31, 2014 12:52 pm

pkrankow wrote:I think I may have missed or misread something...why not use the original case and strap it down?

Does throttle hold position? If it doesn't then you need to hold the throttle position the entire time.

A cheap spread spectrum car transmitter/receiver seems in the same $$ ballpark as where you are going.

I assume you are going to build a full function scale bird, or a carrier plane, with this.

How do you plan to finish the case, black paint or poly varnish?

Phil

I could have used the original case strapped to my leg, but I wanted to have it on the handle, and the original case would have been very difficult and awkward to attach to a handle. Also a lot heavier than this little box. An extra five or six ounces doesn't sound like much, but that's weight being held at arm's length for a few minutes getting heavier that I don't need if I don't have to. Besides, why leave something as-is when I can cut it to pieces and rebuild it again...

It's the normal Mode 2 throttle stick, so yes, it does hold the position it's set to.

I already had the transmitter/receiver/handle sitting in the closet not being used, so cost was $0.00 out of pocket for me. $30.00 shipped for the cheapest car radio I've found is still more expensive, plus the work/expense I'd have to put into it making it into a handle. I'm not sure if you've played much with those car transmitters, but they're way heavier than one of the Blade 4 channel transmitters. Besides, the car transmitter would only be three channels. I need all four channels. I NEED all four channels.

If the throttle control works well on a test bird, I'm thinking of using one channel as a stooge release, with a 5 gram servo on the plane to release a stooge string. I have a nice set of mini-retracts for another channel, and who knows what the fourth channel would be for. If I get really ambitious, I can replace the third and fourth channels with a toggle switch and a pot to use for flaps or something. But, realistically, I'll probably just make sure it works, and then leave it as it is or simply add the rudder channel as a stooge release, because I have so many other projects queued up in my mind. This'll stay as just an electronic throttle for whatever electric plane I want to fly at the moment.

To finish it, I'm just going to shoot it with LustreKote. Since I have a few other planes waiting for paint, I'll just paint this at the same time with one of the colors I'm using. Probably white or red. Or I may get fancy and do a multi-color paint scheme. Depends on my whim at the moment.

The NEEDY Mark

batjac Fri Jan 31, 2014 1:02 pm

RknRusty wrote:Hair Brained, maybe. But creative for sure. And obviously spare time on your hands too.

It's not spare time. It's time carefully hoarded for my sanity. I have my brother-in-law living with us for the past year, my 23 year old stepson moving in and out when he has nowhere else to go, bill collectors calling for my B-i-L or step-son regularly, my B-i-L or stepson or Mother-in-Law regularly borrowing money, my wife recovering from surgeries every few months, and my mother who was living with us passed away a couple of weeks ago. I have lots on my plate recently. I usually trade some sleep time for project time. When I get home from work, my wife usually takes one look at me and says, "Go relax and work on something". She knows I need the decompression time, and working on projects restores my calm.

The "On the Edge" Mark

duke.johnson Fri Jan 31, 2014 2:55 pm

Mark
Take a step back from the edge and breath. I'm sorry to hear of all your trouble. We're here for you though.

we6oz Fri Jan 31, 2014 3:12 pm

Out of curiosity, what did You do with the last bit of the antenna "whip"?

batjac Fri Jan 31, 2014 3:50 pm

we6oz wrote:Out of curiosity, what did You do with the last bit of the antenna "whip"?

Well, it didn't fit too well in the box, and I didn't feel like making an extension out the side, so I just cut it off. No big deal, right? You gotta do what you gotta do... Seriously, though. If you look closely at the picture of test fitting the board in the box, you'll see the antenna is down along the right side of the box. I know it decreases the signal along the path it's going to go to the model, but at the 40-50 feet max range it's going to be needed, it should work okay. If not, I'll drill a hole in the side of the box and use the original antenna housing from the eFlight transmitter.

The Hilarious Mark

batjac Fri Jan 31, 2014 3:50 pm

duke.johnson wrote:Mark
Take a step back from the edge and breath. I'm sorry to hear of all your trouble. We're here for you though.

Thanks, Duke. Much appreciated.

JPvelo Fri Jan 31, 2014 3:52 pm

Mark,
Don't underestimate the value of getting enough sleep when things get crazy. When things spiral in my life and it's hitting the fan proper sleep is one of the things I can control that helps me keep my sanity.

Jim

**RknRusty** Fri Jan 31, 2014 6:09 pm

RknRusty wrote:Hair Brained, maybe. But creative for sure. And obviously spare time on your hands too.

I understand. I had no intention of sounding snarky. I'm glad you have an outlet for creative decompression.
Rusty

batjac Fri Jan 31, 2014 8:58 pm

RknRusty wrote:I understand. I had no intention of sounding snarky. I'm glad you have an outlet for creative decompression.
Rusty

Don't worry, I didn't take it wrong. It was just one of those days today. Feel free to snark away... lol!

The "Can Take a Joke" Mark

we6oz Fri Jan 31, 2014 11:39 pm

batjac wrote:
we6oz wrote:Out of curiosity, what did You do with the last bit of the antenna "whip"?

Well, it didn't fit too well in the box, and I didn't feel like making an extension out the side, so I just cut it off. No big deal, right? You gotta do what you gotta do... Seriously, though. If you look closely at the picture of test fitting the board in the box, you'll see the antenna is down along the right side of the box. I know it decreases the signal along the path it's going to go to the model, but at the 40-50 feet max range it's going to be needed, it should work okay. If not, I'll drill a hole in the side of the box and use the original antenna housing from the eFlight transmitter.

The Hilarious Mark

"No big deal, right?"....well, sorta/kinda-a little....

When you trim or prune an antenna set for a specific frequency you raise the antenna's harmonic resonance which will effect both performance, distance, and eventually "fry" your transmitter final amplifier transistor.

we6oz Fri Jan 31, 2014 11:54 pm

....did you save the end, or remember how long it was?
You can solder an equally long piece of copper wire to the end to adjust for your mismatch, but RF is finicky when it comes to being bent-back towards it's own antenna as well....hmm.
I'd find out the exact freq. on 2.4 you're operating on, and follow the ARRL's recipe for a 1/4 wavelength dipole and draw one on an old unused circuit board, then etch it, cut-off the old antenna, and solder the PC board antenna in it's place.

Kinda getting technical, I know, but I can totally imagine a few different antenna arrangements for that 'lil box.

Oz.

batjac Sat Feb 01, 2014 1:03 am

Oz, read my response again. I didn't really cut the end off of the antenna.

The Apparently Convincing Mark

batjac Sat Feb 01, 2014 1:43 am

Well, I was going to cut a handle out of 1/4" ply for this, but it would take too much effort to pull out and set up the scroll saw right now, so I just used a SIG handle instead. This actually looked much more neat and tidy in my head. But it's functional. It'll look better once it's painted up. I just need some aluminum to bend for a belt clip and attach it to the back. I was going to make a locking tab for the handle, but it's a pretty tight friction fit as is.

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This seems pretty light as I hold it up at arm's length. I'll pull out another stock Blade transmitter and do a weight comparison between that and this rig.

The Untidy Mark

ian1954 Sat Feb 01, 2014 3:51 pm

Another interesting series of postings.

I am watching this one closely - idea stealing again!

batjac Sat Feb 01, 2014 8:23 pm

So I hooked the receiver to a plane and gave it a shot. It worked pretty good. I'll tach it sometime when I can get outside while it's light out. But, I had the wife take some shots while I hold it to show that, yes, it really does work. Now to just paint it up and put the tab on the back and it'll be finished.

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I even went so far as to take a few minutes and figure out how to upload my first video to YouTube.

The Almost Finished Mark

batjac Sun Feb 09, 2014 7:10 pm

Mine may be ugly, but it's certainly cheaper and lighter than this one:
http://stunthanger.com/smf/index.php?topic=33111.0

Looks like he just took a Losi radio and mounted a piece of 1/16" aluminum angle to it.

The "Easy on the Wallet, Not the Eyes" Mark

batjac Fri Feb 14, 2014 8:08 pm

The weather wasn’t rainy yesterday, though it was humid, so I figured I’d paint up the box. Since it’s just an experiment, I didn’t worry about how the paint would look when it dries due to the humidity. And, since this for electric and wouldn’t see any glow fuel, I just put a couple of light coats of paint, not trying to get the best, even color and coverage out of it. I would have preferred to paint it black, but keeping with the theme of just using leftovers I have on hand, I used some Royal Blue Lustrekote I had left from my Baby Ringmaster project.

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Weighing the new box and comparing it to an original Blade transmitter, it only weights a little more than 1/4 of the original transmitter weight, shedding eight ounces, or 218 grams. Stock:

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After:

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If it’s not raining tomorrow, I’ll take the rig out to test fly it. The EMAX 2812 motor I used for the plane is a 140 Watt motor. I haven’t used my wattmeter to select the prop to get the most power out of the motor, but I used the suggested 7x4 prop, so it should pull close to max power. Using the target of 11 watts/ounce that is suggested over on Stunthanger, that comes out to 12.72 ounce target weight for the plane (140/11 = 12.72). Weighing the plane and the electric components came out to 12.8 ounces. Serendipity, indeed! So, figuring the 11W/oz is good for an acro C/L plane, it should at least fly this plank wing in circles with no problem. We’ll see on the morrow.

I’m off to cut some coroplast for an electric Osborne Platter to get the son in the air next weekend using the e-flight timers I bought a couple of months ago, along with the other EMAX motor I have awaiting the outcome of this experiment. He has a Babe Bee powered platter he likes to fly, so this should be an easy transition for him to e-flight.

The Serendipitous Mark

batjac Fri Feb 14, 2014 10:12 pm

Oops! Just remembered that I haven't range checked this yet. So, I taped a flag to a servo and put it out on the front entry. Then I walked backward while moving the throttle up and down, watching the flag to ensure it was still getting a signal. I walked back 70 feet, and still had a signal, so it should have no problem on the 35 foot lines I'll use.

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Man! Looking back on this post, I'm pretty long-winded. Ah, well. 'Least you know I'm still alive...

The Ranger Mark

ian1954 Sat Feb 15, 2014 6:03 am

Remember to do the range check when the equipment is mounted in the plane and all set up ready to fly. I have found that strange combinations affect range.

I recently built a small Park Flyer and fitted carbon push rods for lightness. It failed the range test!

I read that carbon rods affect range and so I replaced them. Still failed the range test!

Swapped the receiver and still failed.

Moved the receiver backwards 1/4" and it passed. It then passed with the original carbon rods.

????????

batjac Sat Feb 15, 2014 2:43 pm

ian1954 wrote:Remember to do the range check when the equipment is mounted in the plane and all set up ready to fly. I have found that strange combinations affect range.

I recently built a small Park Flyer and fitted carbon push rods for lightness. It failed the range test!

I read that carbon rods affect range and so I replaced them. Still failed the range test!

Swapped the receiver and still failed.

Moved the receiver backwards 1/4" and it passed. It then passed with the original carbon rods.

????????

Thanks, Ian. I'll range check it as ready to fly. I mounted the receiver inboard so it has a line-of-sight connection to the box, but it can't hurt to verify.

The Huh...

Mark

fredvon4 Sat Feb 15, 2014 4:44 pm

For what it is worth...carbon fiber is conductive...just saying

I can NOT (with decades of Ham Radio and extensive RF training) understand why a Fuselage with carbon longerons have ANY effect on a 2.4Mhz receiving system, unless they are acting as a FARADAY cage (UNLIKELY)

I suspect antenna orientation was the problem (why many many 2.4 folks use multiple antenna modules)

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