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Building Tips and technical articles. => 1/2 A building. => Topic started by: Greg Knipp on February 20, 2025, 07:52:18 AM

Title: Larry Rengers ET1 1/2A Trainer
Post by: Greg Knipp on February 20, 2025, 07:52:18 AM
Hello, I am new to the forum and am looking to leave the RC world and do control line flying.  At any rate, I found an older thread on this ET1 Trainer which looks like just the ticket for me to get going with.   I was wondering if anyone has any further information, plans, kits, etc... that one could point me to, I would be very thankful.
I am so undecided as to the ideal trainer for someone who has not flown in many years, not to mention very seriously.
Any help or guidance would be appreciated
Thank you.
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Greg Knipp on February 21, 2025, 08:15:00 AM
After doing more searching, I did find the PDF drawings posted by Larry. Thank you, Larry for all of the information.
I'll figure out how to successfully navigate this forum yet.
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Larry Renger on February 22, 2025, 08:07:23 AM
The ET1 was designed to fly in the limited space available at various shows and exhibitions. If you have more room, scaling it up for longer lines and more power would be beneficial.

🤠
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Greg Knipp on February 25, 2025, 04:55:25 AM
Thanks for chiming in Larry and thank you for the suggestion.  If i may, please,  I would like to ask for your help.  Based on original size:
1.)  How much tip weight did you use?
2.)  Any right or up thrust on motor?  If so, how much?
3.)  Is horizontal stab just butt glued to crutches  or am I missing something? Seems like a very weak spot.
4.)  What size motor, prop, battery do you recommend?
Thank you, again, for your guidance.
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Larry Renger on February 25, 2025, 08:37:32 AM
It has been a long time since I did that model, but I’ll do my best.

The horizontal stab should fit into slots in the booms.
No motor offsets
We used a quarter for tip weight
I am fuzzy on the power details, but I think we used a 7” x 5” prop. The batteries were 850 3S.
Lines were 20’ 10lb Spiderwire

I’ll see if I can get better data on that.

🤠
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Greg Knipp on February 25, 2025, 05:53:04 PM
Ok, thank you.  The plan doesn't show slots on the booms for tail, but easy enough to add.
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Larry Renger on February 25, 2025, 07:25:47 PM
The motor was a Turnigy 2627-1200

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Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Larry Renger on February 25, 2025, 09:15:35 PM
Prop was left hand electric APC.

Spruce spars, but carbon rods would be better.
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Larry Renger on February 25, 2025, 09:19:32 PM
3” bellcrank, elevator travel under 20 deg.
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Greg Knipp on February 26, 2025, 05:39:01 PM
Oops.
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Greg Knipp on February 26, 2025, 05:41:38 PM
Thanks again Larry.  Could you please post some pictures of how you attached the tail to the booms as there are no slots shown in either part.
I'm also curious as to how the landing gear is attached.
Thanks again.
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Larry Renger on March 05, 2025, 05:52:57 PM
Did you get all the information you need? Pm me your e-address if you need more. I found my files and photos.

And, today I retrieved one of the models. I should be able to answer any and all questions.

🤠
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Greg Knipp on March 25, 2025, 11:37:34 AM
Larry, yes, I recieved all of your info and thank you so much.
The only thing I need to do is find a motor.  I have a 2205 / 2300kv I'm thinking might be appropriate.  What ate your thoughts?
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Larry Renger on March 26, 2025, 07:04:21 AM
 I know very little about motor sizing. I recommend posting the question on the electrics segment.

I’ll weigh my model and measure the wing area and get back to you.

I think the Brodak site may have charts.
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Larry Renger on March 26, 2025, 04:08:59 PM
The one I have weighs 11oz with battery. Wing area is 117 sq- in

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Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Jeff Zhu on March 30, 2025, 08:23:45 PM
Hi Larry,

I'd love to give this plane a try. Although it's a basic C/L trainer, I'm curious to see if it can perform maneuvers like a vertical 8. I'm interested in hearing about your flight experience with it.

Thank you!

Jeff
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Larry Renger on March 31, 2025, 03:35:24 AM
It’s a trainer. It goes around in level circles. That is all it does. But it does it very well. We trained about 1000 kids over several years and still have the original models.

You could scale it up and build one from balsa with an airfoiled wing. Then you could do vertical eights.

🤠
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Jeff Zhu on March 31, 2025, 07:47:55 PM
Great to know that. Thanks, Larry.
Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Larry Renger on April 04, 2025, 06:26:19 AM
So, anyone building one? It is a good model to have at your flying field to introduce any spectators to CL flying. Or you could build several and race them.

Substitute a simple timer for the radio system we used. Pit stops for timer reset and battery change.
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Title: Re: Larry Rengers ET1 1/2A Trainer
Post by: Larry Renger on May 15, 2025, 06:15:29 PM
Any progress?