Author Topic: Knights of the Round Circle electric trainer, the ET-1 (Read 22100 times)

Larry Renger · « **on:** July 23, 2012, 10:54:31 AM »

Since we do U/C training for kids at various airshows, we wanted to replace our aging fleet of PT-19s with an electric trainer. It should be a lot easier to run the show and require fewer people.

Guess who got the job of design?

Anyway, the model is 26" span and made from Coroplast (raided from abandoned political signs). Weight is 12.7 ounces with a 1000 mAH 3S battery. We can put 10 flights of 10 laps each on a single battery, leaving over 20% margin as is needed by LiPo cells.

Landing gear are shock sprung by rubber bands, and the prop doesn't touch the ground even if you drag the tail. The rear gear wire is pivoted in aluminum tubes sewn to the surface of the wing. The front pivots on ply disks on both sides of the fuselage.

Bill Little · « **Reply #1 on:** July 23, 2012, 11:29:12 AM »

Looks very functional, and a pleasing design!

BIG Bear
RNMM/AMM

Dan McEntee · « **Reply #2 on:** July 23, 2012, 11:34:47 AM »

Isn't it refreshing to find a good use for political signs!!!?? That is what we made the prototype TuffBabies from. We've been using the same 5 airplanes at KidVenture for the last 2 years and they have been used for at least 3500 to 4000 flights. Might have replaced a part or two hear and there. We based our design on a super tough fuselage, and replaceable wings and tail surfaces. haven't broken one yet through countless lawn dart approaches! Good luck with your design, and will you be making any plans or outlines available? I do like the sort of Vampire look of the airplane.
Type at you later,
Dan McEntee

Derek Moran · « **Reply #3 on:** July 23, 2012, 11:52:16 AM »

There are some really clever details in your design and I'm sure it flies well for its intended purpose. The pusher configuration is inspired.
You seem to have a talent for this. Have you ever thought of designing model airplanes for a living?
Good work, Larry!
Derek

Crist Rigotti · « **Reply #4 on:** July 23, 2012, 12:43:52 PM »

Quote from: Larry Renger on July 23, 2012, 10:54:31 AM

Since we do U/C training for kids at various airshows, we wanted to replace our aging fleet of PT-19s with and electric trainer. It should be a lot easier to run the show and require fewer people.

Guess who got the job of design?

Anyway, the model is 26" span and made from Coroplast (raided from abandoned political signs). Weight is 12.7 ounces with a 1000 mAH 3S battery. We can put 10 flights of 10 laps each on a single battery, leaving over 20% margin as is needed by LiPo cells.

Landing gear are shock sprung by rubber bands, and the prop doesn't touch the ground even if you drag the tail.

Looks like just the ticket for my 6 year old grandson to learn on! Any sketchs or drawings? thanks.

Larry Renger · « **Reply #5 on:** July 23, 2012, 12:50:04 PM »

" Have you ever thought of designing model airplanes for a living?" What an idea! Do you really think I could?

I'll clean up the sketches and make it into a .pdf I think it will post here, but if not, I can e-mail it on request.

Crist Rigotti · « **Reply #6 on:** July 23, 2012, 01:02:09 PM »

Quote from: Larry Renger on July 23, 2012, 12:50:04 PM

" Have you ever thought of designing model airplanes for a living?" What an idea! Do you really think I could?

I'll clean up the sketches and make it into a .pdf I think it will post here, but if not, I can e-mail it on request.

Thank you Larry!

Andrew Borgogna · « **Reply #7 on:** July 23, 2012, 01:20:25 PM »

Gee Larry could you tells us something about the power system and how you control the throttle, I sure would be interested to learn more.

Andy

Wynn Robins · « **Reply #8 on:** July 23, 2012, 02:08:52 PM »

I'd like a copy too Larry - my 4yr old will love it!!!

cool looking plane too - well done!!!!

Tim Wescott · « **Reply #9 on:** July 23, 2012, 02:11:28 PM »

It looks like it'd be a good sport flyer with all balsa construction.

I, too, would like plans.

Larry Renger · « **Reply #10 on:** July 23, 2012, 04:00:13 PM »

Andy:

Andy set up the power system. It uses a Maitian 2208/15 motor from Hobby People. Their sku number is 129012. I don't know what the esc is because Andy glued it to the plane with the label in. I expect that a 12 Amp unit will do. The flight is controlled by a Spectrum 6 tx (2.4 gH) from outside the circle with an AR6000 rx on the plane. The prop is an APC 7x5 cut to 6-1/4" diameter.

Battery is a 1000 mAh 3S 20c. We got ten flights of ten laps each on one battery charge with 24% charge left at the end. Perfect!

I expect you could get away with a 500 mAh cell or smaller if you aren't training a hundred kids in a day. We are guessing that 10 laps is about all the average kid can handle. We will see on Aug 5th at the airshow at Compton Airport in CA. Y'all come!

Larry Renger · « **Reply #11 on:** July 23, 2012, 04:29:45 PM »

Let's see if these .pdf files will post.

The drawings should print out full size on 22"x34" paper with a 1/4" border.

Andrew Borgogna · « **Reply #12 on:** July 23, 2012, 06:26:45 PM »

If I remember right the ESC is a 36amp (over kill) CC Thunderbird unit. All kidding aside Larry did a heck of job coming up with this plane. We were getting desperate since our stock of Cox PT-19s had just about run out, and the plane was a nightmare in wind. This plane actually fly decent in wind. It really looks to be a good trainer.

Andy

david beazley · « **Reply #13 on:** July 23, 2012, 06:59:31 PM »

Larry, this is great! I have been noodling around in my head an electric pusher trainer for kids and it looks like you read my mind. I love the idea of a pusher for trainer as we all know the propulsion system hits the dirt first in a trainer. Electric, for a noob is no muss, no fuss, and it would get more people in the air with less hassle.
Great work!

bill bischoff · « **Reply #14 on:** July 23, 2012, 07:50:56 PM »

I applaud your efforts, sir.

Now, at the risk of being severely chastised for being critical, let me offer this comment. In these days of instant gratification flashy RC RTF's, control line has an image problem with kids. It's not "cool" (although we all know better). Why not hit it with some spray paint and a few stickers to make it into a jet fighter instead of a reclaimed yard sign? It might boost the image a bit.

Larry Fernandez · « **Reply #15 on:** July 23, 2012, 07:59:54 PM »

Quote from: bill bischoff on July 23, 2012, 07:50:56 PM

I applaud your efforts, sir. Now, at the risk of being severely chastised for being critical, let me offer this comment. In these days of instant gratification flashy RC RTF's, control line has an image problem with kids. It's not "cool" (although we all know better). Why not hit it with some spray paint and a few stickers to make it into a jet fighter instead of a reclaimed yard sign? It might boost the image a bit.

Hey Larry, I guess I could Mono-Cote it when I come down.

Larry Buttafucco Stunt Team

Larry Renger · « **Reply #16 on:** July 23, 2012, 08:19:53 PM »

That one is the test model. What do you take me for, a barbarian?

I have 3 more in the works for the actual training. One is all black with pirate skulls, the next one is red, white and blue, and the final one will be painted like the good old PT-19.

Photos when they are done.

to Evil Larry: do you actually know how to Monokote?

Dennis Adamisin · « **Reply #17 on:** July 23, 2012, 08:23:21 PM »

That's GREAT! the pusher layout should help survivability and the RC control for on/off is just the ticket. The 35A ESC is overkill but should also provide a lot of reserve if you ever get a prop dragging kind of event happen. The difference in weight versus a 12A ia not a deal breaker either.

Great job Larry & great job Andy!

By the second week in November we should have a near limitless supply of building material too!

Larry Fernandez · « **Reply #18 on:** July 23, 2012, 08:55:51 PM »

Quote from: Larry Renger on July 23, 2012, 08:19:53 PM

That one is the test model. What do you take me for, a barbarian?

I have 3 more in the works for the actual training. One is all black with pirate skulls, the next one is red, white and blue, and the final one will be painted like the good old PT-19.

Photos when they are done.

to Evil Larry: do you actually know how to Monokote?

WHAT!! Did you not see my black Still Stuka??

Larry, Buttafucco Stunt Team

Larry Renger · « **Reply #19 on:** July 23, 2012, 08:57:44 PM »

"By the second week in November we should have a near limitless supply of building material too! "

So true, and most of it becomes garbage! Save the world, build an ET1! Or 5. Give them to kids! Build them as just swing around models with no power. The possibilities are endless. The material costs just the gas to drive around the neighborhood, or would walking kill you?

Larry Renger · « **Reply #20 on:** July 23, 2012, 08:58:43 PM »

To Larry: The tail is still in Warren's Man Cave. When y'all gonna come get some Tri-Tip and fixins? We ain't had nobody new to hassle for months!

Larry Fernandez · « **Reply #21 on:** July 24, 2012, 11:03:01 AM »

Quote from: Larry Renger on July 23, 2012, 08:58:43 PM

To Larry: The tail is still in Warren's Man Cave. When y'all gonna come get some Tri-Tip and fixins? We ain't had nobody new to hassle for months!

Larry, At the next Thursday build night, get one of the SoCal smarta$$e$ to get a picture of that plaque and post it.
I laughed my ass off when I saw that thing hanging on the wall. And not a bit of sympathy from Warren.

Larry, Buttafucco Stunt Team

Steve Helmick · « **Reply #22 on:** July 24, 2012, 03:29:53 PM »

Larry Renger wrote: "The flight is controlled by a Spectrum 6 tx (2.4 gH) from outside the circle with an AR6000 rx on the plane."

What the ____ is that all about? What for? RCDT?

Steve

philip metzner · « **Reply #23 on:** July 24, 2012, 05:13:31 PM »

Larry, could you comment on the thickness of the coroplast material, and what kind of glue to use? I built a little bi-plane and it was heavy and the hot glue joints failed right away.

Larry Renger · « **Reply #24 on:** July 24, 2012, 10:46:04 PM »

Steve, what is RCTD? Radio control dethermalizer? No, it is to limit the length of the flights with raw beginners who will ralph their guts if they go too long. We think 10 laps is about right, but will keep that under advisement. Also, every once and a while we come across some clown who WANTS to crash the model. Sorry, dude, your power just got cut!

The Coroplast is about 1/4" thick and pretty heavy, but for our purposes, that is not a problem. We DON"T want the plane to be very responsive, especially to gusts and wind drift. I am using Hot Melt type glue, and it does let go if under steady stress. That is why the landing gear are secured by sewing and CA the way they are. Hot Melt let go after a couple of days pressure from the landing gear spring rubber bands.

I suspect that some sandpaper roughening of critical areas would do wonders for improving the joint stabilities.

The next 3 models are being painted prior to assembly. I hope THAT works out. Not too much weight gain and no loss of bonding strength. Time will tell! Also, the wing is split at the center due to the size of the sign planels available. Spruce 1/8x3/16 joiners SHOULD take care of that joint.

I appreciate all the interest in this design, and when it is proof tested and finalized, I will look into publishing it, probably in Model Aviation to get the most effective coverage to the widest audience.

Phillip Kenney · « **Reply #25 on:** July 25, 2012, 09:39:33 AM »

While by no means a coroplast expert builder, I have read that where you are going to glue a part you should hit the area first with a small blowtorch to burn off the residue from construction. I built a wing for a control line plane and the trailing edge joint is holding up just fine.
For additional info check under SPAD building.

john e. holliday · « **Reply #26 on:** July 25, 2012, 11:03:34 AM »

Hey Larry, how about getting Eric to kit a complete package. I think that is what Jim Walker did with the A-J Firebaby ready to fly plane. Oh it did take a couple of minutes to read instructions and bolt together. Or was that read instructions after trying to bolt together.

Larry Renger · « **Reply #27 on:** July 26, 2012, 11:45:06 PM »

I have asked Eric to see if he can cut coroplast with his laser. I could then add all sorts of registration tabs, and the fits would improve.

Major thanks to Mike Alurac who assembled all 3 new models this evening. By the third one, it only took 30 minutes! I also thank Dave Kick for cutting out the parts for the 3 new models.

Eric certainly could at least put the hardware package together with a set of plans. Coroplast is pretty expensive if you buy it outright. Of course the election is coming! You can get three planes out of 2 - 24x36 signs.

For personal use, the model could be done in balsa.

Michael Alurac · « **Reply #28 on:** July 27, 2012, 12:07:42 AM »

Larry you are a consumate advocate of the control line world and you've just hit a home run with these electric cl trainers! Very impressive and I hope that they get a good look here on Stunt Hangar. I could see my neighborhood kids flying these like back in the days of my childhood in the 70's using Cox RTF products. Hopefully this will get kitted for cl clubs to access across the country. I must say that I had a great deal of fun building these fine trainers together with you this evening. The first one took longer as I was putting a nice finish on the hot melt glue fillets to make them look purty. And yes the builds did speed up considerably by the third one. I'm thinking the fourth one could be assembled as quickly as 20 minutes! Great trainer design, can't wait to see them in-flight at the EAA Event at the Compton airport on Aug. 5th! I will see you there!

Steve Thornton · « **Reply #29 on:** July 29, 2012, 01:57:05 PM »

Great job Larry, I am a beginner-again-after a 40 year layoff and I am very interested in e-planes, not only for myself, but my grandsons. I have built a 1/2 A from coroplast and a yard stick, and I love the material, but I know nothing about electrics and have many questions. What is the cost of the motor, ESC, battery, etc, and will this design make as good a stunt trainer as it looks like it will? Is there a tutorial, book, or DVD that I could find for the basics and system requirements? Oh yeah, what adhesive do you use for the coroplast?

Thanks, too, for your contribution, especially to the next generation of CL modellers.
Steve Thornton

Tim Wescott · « **Reply #30 on:** July 29, 2012, 02:45:42 PM »

Steve, if you look at Larry's reply number 10 he lists all the motive system parts.

If you do it per Larry's description then you don't need a timer -- you can just use an RC receiver, which means that anyone who understands RC electric can help you set it up.

If you want to go cheap, check Hobby Partz or Hobby King (there are others). For something that's gonna crash a lot that's probably best. I like the way Larry's designed the thing -- all the really delicate parts are protected by at least a bit of fuselage. Full bore into pavement from a wingover is probably going to toast the battery, but I think you'd still come out of it with all the rest of the electronics intact.

Larry Renger · « **Reply #31 on:** July 29, 2012, 03:22:05 PM »

Sorry, but this plane will never stunt. Way too heavy for the wing. The bad news is that it only flies level. The good news is that that is all it is supposed to do, and it does it even in windy conditions.

The motor is supposed to go on sale on August 1st at Hobby People. If there isn't one within reach, they have an excellent website. The rest of the stuff can be had from Hobby King. You can get a 2.4 gHz radio for about $50 from them too!

Larry Renger · « **Reply #32 on:** August 01, 2012, 07:59:25 PM »

OK, the three final version models are essentially done. I need to set up lines on the black and RWB versions, but the electronics is all velcro on at the field. We flew the PT-19ish one this morning and it is a real treat. Flies on 1/2 power very well, and on longer lines at full power, I'll bet I could do loops, eights and inverted.

Here are photos:

Michael Alurac · « **Reply #33 on:** August 01, 2012, 10:58:56 PM »

Lookin' good Larry. Can't wait to see them in flight this weekend!

Mike

Larry Renger · « **Reply #34 on:** August 03, 2012, 10:23:07 PM »

We had our first crash! On camera! Flown by the reporter herself! Here is the link. I am the fat guy in the blue jacket. www.ktla.com/news/local/gayleanderson/

The motor mount shattered,but the rest of the plane survived with no visible damage. I already have a plan!

Phillip Kenney · « **Reply #35 on:** August 05, 2012, 01:01:11 PM »

The link brings you to a general page for the chanel. Which video shows the C/l flying?
Thanks, Id like to see the performance of the planes.

Larry Renger · « **Reply #36 on:** August 06, 2012, 07:58:14 AM »

Just below the main screen is a series of panels. Click on them to see each film clip. The arrow on the right will bring up more clips.

BTW, we had our training session yesterday at the Compton Airport EAA fly-in. We got through the entire day with just one model! And it is still flyable. A little paint touch up on the nose, and it is good as new. Not only did we have no required repairs, we were able to fly in much more wind than we ever could with the PT-19.

Phillip Kenney · « **Reply #37 on:** August 06, 2012, 11:10:34 AM »

Ok, I know little or nothing about electric power systems but I have put together a system from Larry's description and have a question on the prop. The mentioned APC 7x5 prop, is it a pusher prop, is the motor run in a "pulling configuration" but on the back or what?
Thinking Id like to give one of these a try so Im trying to order all I need at one time.

John Cralley · « **Reply #38 on:** August 06, 2012, 11:18:27 AM »

Hi Phillip,

Since an electric motor will run equally well in either direction, you can use either a "puller" or a "pusher" prop to power the model! Just be sure you mount the prop facing toward the front of the plane and that you have the correct motor direction.

By the way, you can change the motor direction simply by swapping any two of the three wires that connect it to the ESC (assuming you are using an "outrunner" motor).

Larry Renger · « **Reply #39 on:** August 06, 2012, 02:43:14 PM »

For this trainer, the motor torque rolling the model will be more favorable with a "pusher" prop. It matters very little so long as the air goes out the back, not the front.

Steven Herbert · « **Reply #40 on:** September 29, 2012, 07:10:23 PM »

Larry, I will be building this model (out of balsa), and would like to know what type of lines you are using, and what length. One of the posts mentioned that it may loop on full length lines, is there a "trainer" length and an "advanced trainer" length?

Michael Alurac · « **Reply #41 on:** October 07, 2012, 09:55:01 PM »

KOTRC Club members Tom Collier (not pictured), Larry Renger, John Wright, Mike Jones, Mike Alurac and Mike Costner supported more than 145 training flights at the Fullerton Airport Day 2012 Saturday October 6, 2012. The squadron of electric trainers cleverly named ET-1 for you might have guessed it Electric Trainer 1 successfully flew nearly non-stop for 6 hours on the tarmac of the Fullerton Airport thrilling the children and adult visitors alike with their hand at the controls of a control line model airplane!
Each of the 145 pilot trainees received 7 laps on the club trainers and was awarded a flight training certificate after their flight documenting this exciting opportunity. We had many interested individuals visiting our booth looking to join us at the Oct. 9 regularly scheduled club meeting and others wanting to purchase an ET-1 for their entry into CL flying. Bill Jr. of AFI greatly thanked the crew and their volunteer training efforts and greatly appreciated our club’s effort to expose aviation of all types to the new generations of local children by offering an entry into model aviation. We too thank AFI and Bill Jr. for their hospitality.

Larry Renger designed and built the ET-1 along with a little help from Dave Kick and Mike Alurac during the final assembly stage and others like our club’s C/L electronic flight authority Andy Borgogna for assisting with engineering the electronic propulsion system. Andy set up the power system using a Maitian 2208/15 motor from Hobby People sku number is 129012. I don't know what the esc is because it was glued it to the plane with the label in but I expect that a 12 Amp unit will do. The flight is controlled by a Spectrum 6 tx (2.4 gH) from outside the circle with an AR6000 receiver on the plane. The prop is an APC 7x5 cut to 6-1/4" diameter.

Larry explained a bit more of the background story leading to the need to design an easy to fly and support electric CL trainer.
“Since we do U/C training for kids at various air shows, we wanted to replace our aging fleet of Cox PT-19s with a reliable easy to support electric trainer the ET-1. It was a lot easier to run the show and required fewer people. Guess who got the job of design? Anyway, the model is 26" span and made from coroplast (raided from abandoned political signs). A nearly unlimited supply of coroplast is bound to emerge soon during this political campaign season. Weight is 12.7 ounces with a 1000 mAH 3S battery. We can put 10 flights of 10 laps each on a single battery, leaving over a 20% margin as is needed by LiPo cells.

Landing gears are shock sprung by rubber bands, and the prop doesn't touch the ground even if you drag the tail. The rear gear wire is pivoted in aluminum tubes sewn to the surface of the wing. The front pivots on ply disks on both sides of the fuselage”.

With this air shows success by far surpassing the 88 air show flight training record of previous events, high interest and success of the ET-1 we hope to see the Knights sponsor C/L training opportunities at the upcoming AMA Expo January 11-13, 2013 at the Ontario Convention Center with the ET-1.

A great job was done by all of the participating club members and directly contributed to this shows success. Keep up the good work promoting our C/L hobby guys!

Mike Alurac
AMA 63056

john e. holliday · « **Reply #42 on:** October 08, 2012, 08:08:34 AM »

This sounds great fellows.

mike londke · « **Reply #43 on:** October 08, 2012, 08:56:25 AM »

With all the talk of coroplast trainers on this thread I thought it would be ok to post this here. This is a short video of my son Sam flying one when he was 3 years and 7 months old. They are great for training you can pound them in over and over.

minnesotamodeler · « **Reply #44 on:** October 08, 2012, 04:21:12 PM »

Quote from: Larry Renger on August 06, 2012, 07:58:14 AM

Just below the main screen is a series of panels. Click on them to see each film clip. The arrow on the right will bring up more clips.

BTW, we had our training session yesterday at the Compton Airport EAA fly-in. We got through the entire day with just one model! And it is still flyable. A little paint touch up on the nose, and it is good as new. Not only did we have no required repairs, we were able to fly in much more wind than we ever could with the PT-19.

So you couldn't tell us which one you're on, we're sposed to wade thru a couple dozen b-o-o-o-r-r-i-i-n-n-g-g news bits looking for you? nope, not gonna do it. It'll hafta go un-watched by me.

Larry Renger · « **Reply #45 on:** October 08, 2012, 05:31:14 PM »

I just went to the KTLA site and Gayle Anderson and did a search on Compton, and here it is: http://www.ktla.com/news/local/viewerinfo/ktla-eaa-96-flyin-and-model-expo-20120803,0,2201662.story

Video star me!

Larry Renger · « **Reply #46 on:** October 14, 2012, 09:43:13 PM »

Last weekend, at the Fulllerton Airport public days, we trained enough kids to issue 145 certificates, and there were several repeats in addition. We had one motor failure that was resolved later as a non issue, and one broken motor mount repaired on the field; otherwise, we just recharged batteries all day, got dizzy and absorbed rugrat germs. (I have a cold!)

I can say that a transmitter that uses simple AA batteries is the way to go, because the recharge time is seconds, not hours.

We flew pretty steadily for 5 or 6 hours (it became a bit of a blur), and Mike Alurac had brought his generator so my 2 chargers and power supply were required to keep the action going.

We were getting close to a tie between recharging and running out, but one more battery would have kept us going indefinitely. We started with 6 chaged batteries good for 70 laps each. (2 batteries were damaged by crashes that would have made the difference). There are 4 battery chargers available, and next time one of those will make the BIG difference.

If you are a reasonably close, local club and want to stage a beginners' day. Let us know, we have the POWER!

Michael Alurac · « **Reply #47 on:** October 15, 2012, 11:09:55 PM »

This would sure be a lot of fun to provide CL training at the AMA Expo in Ontario, CA this Jan! Could we do it indoors or out in an open parking lot area?

Larry Renger · « **Reply #48 on:** October 17, 2012, 02:01:54 PM »

We can shorten the lines as needed, and add "flaps" for lower speeds if necessary. I am sure we can do it indoors.

jim gilmore · « **Reply #49 on:** November 08, 2012, 01:07:26 PM »

How manuverable are these lil planes ??