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Jan 16, 2019, 12:29 PM
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Lynxman's Avatar
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Quote:
Originally Posted by apocalypsedude
Just some thoughts.

The motors get usually pretty hot in those planes, so it might be not a bad idea to print the front parts of the fuselage with PETG at least.

Personally I like more direct linkages for T-tails, especially when the planes are fast.
So I would prefer a servo sitting in the vertical stabilizer, with a short pushrod attached to the elevator.
There simply isn't room for a servo, and I think I would have to make a really long nose to offset the weight. I used to use steel pull-pull cable back in the day which worked great with small planes like this. The ends can be tinned to increase rigidity where it's unsoppurted by a channel.

Yup a PETG nose is a good idea. I will use PLA since it's cold here.
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Jan 16, 2019, 02:44 PM
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Quote:
Originally Posted by Oleander85
Maybe a version where you glue a plywood motormount from the inside?
Good idea! Either plywood or glass fibre, just some material that is more heat resistant than PLA or even PETG.

Concerning the servo in the tail. I was afraid there isn't enough space but I guess it will work with the servo sitting unter the wing, too.
Jan 16, 2019, 02:49 PM
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And another idea...
What about a version for an extermal mounted outrunner motor?

I mean something like that:

Jan 16, 2019, 03:00 PM
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Lynxman's Avatar
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Yes I plan to add a nose for external outrunner mounting that partially hides the motor. A motor can be mounted to the existing nose if you don't mind the ugly look. The nose has 16 mm and 19 mm bolt circles which are very common.
Jan 16, 2019, 03:41 PM
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Lynxman's Avatar
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I added a nose for front mounting outrunners now. 28 mm diameter and 20 mm length motors fit inside the cavity in the front of the firewall. I wanted it to be big enough to completely enclose a drone motor with integrated ESC. If you don't want to enclose the motor you can drop the part down into the bed by 20 mm and it will print without the shroud.

I also added a version with no firewall, but simply a 28 mm hole in the nose, for glueing in a plywood or similar firewall, or even glueing in an inrunner directly.

https://www.thingiverse.com/thing:3358880
Jan 16, 2019, 05:05 PM
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All done. Would be awesome to hear if someone builds and flies it. I can't fly for weeks. The sun doesn't even come up until the end ofthe month.
Jan 16, 2019, 05:33 PM
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Mattestrom's Avatar
Quote:
Originally Posted by Lynxman
All done. Would be awesome to hear if someone builds and flies it. I can't fly for weeks. The sun doesn't even come up until the end ofthe month.
Looks great! I will print it for sure

Edit: Regular 9g servos (like hxt900) are out of the question for the wing? :P
Last edited by Mattestrom; Jan 16, 2019 at 05:39 PM.
Jan 16, 2019, 06:44 PM
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Lynxman's Avatar
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They will stick out a little, but will probably work fine. Apply some tape over them to fair them in with the wing surface. Sub micro 9 mm thick servos will barely fit in the wing.

Note. I updated the fuselage parts now to a new version with wider channel for the elevator control rod as my first print ended up with a fused channel.
Jan 16, 2019, 07:16 PM
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Mattestrom's Avatar
Recommended print settings would be nice Im guessing 0% infill.. bottom/top/outer layers?
Jan 16, 2019, 07:19 PM
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Lynxman's Avatar
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Single 0,4 mm perimeter, 0% infill and four top and bottom 0,2 mm layers works for almost all the parts. The usual RC plane print settings.

The nose should be printed with a 100% infill firewall. The rest 0%. The nose can also be printed with two perimeters if extra strength or nose weight is needed. It adds about 10g.
Jan 17, 2019, 01:57 AM
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Thoemse's Avatar
Quote:
Originally Posted by apocalypsedude
Just some thoughts.

The motors get usually pretty hot in those planes, so it might be not a bad idea to print the front parts of the fuselage with PETG at least.

Personally I like more direct linkages for T-tails, especially when the planes are fast.
So I would prefer a servo sitting in the vertical stabilizer, with a short pushrod attached to the elevator.
I got some experience with hot motors. I had two northern pikes burning lately. I overloaded their motors making them burn down.

My experience:
You obviously don't use PLA for a firewall - it just wont work. Annealing HT PLA might be an option though.
PETG: Better and workable for low power setups. It will melt on a hot motor though.
ABS: This one is rock solid so far.

Another fact I learned: If the motor mount melts the motor will burn up soon after. If your setup makes your plane melt it will burn down either way.
Jan 17, 2019, 02:22 AM
Registered User
Quote:
Originally Posted by Lynxman
I added a nose for front mounting outrunners now. 28 mm diameter and 20 mm length motors fit inside the cavity in the front of the firewall. I wanted it to be big enough to completely enclose a drone motor with integrated ESC. If you don't want to enclose the motor you can drop the part down into the bed by 20 mm and it will print without the shroud.

I also added a version with no firewall, but simply a 28 mm hole in the nose, for glueing in a plywood or similar firewall, or even glueing in an inrunner directly.

https://www.thingiverse.com/thing:3358880

Thanks a lot, man!
Jan 17, 2019, 12:52 PM
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Lynxman's Avatar
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I changed the fuselage parts now to enlargen the wing seat hole to make it easier to install batteries.
Jan 17, 2019, 02:19 PM
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Lynxman's Avatar
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The elevator control rod channel is designed 2 mm, but it wil be much thinner when printing because of how FDM printing works. A 1,2 mm wire will barely go through the channel on my tail part. I will use a 1 mm wire. I have a 0,8 mm wire now which runs super easy through, but ends up with about 1 mm of play in the control.

BTW. Bicycle shifter cables are 1,2 mm, so they can be used in many cases. It's plenty stiff enough to not buckle in the unsupported ends with a plane this small. The forces are low.
Jan 17, 2019, 03:06 PM
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Dirty Dee's Avatar
Very cool Lynx!


Quote:
Originally Posted by Lynxman
I have lots of projects going at once now. Thinking about designing another car too.
Any hints as to what else you have planned for aircraft ?


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