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MIG21F13 in scale 2/7 project thread

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MIG21F13 in scale 2/7 project thread

Old 01-28-2022, 08:04 AM
  #26  
lavi rider
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Not busting balls here … but 2/7 = 1/3.75 …. Right .. 4/14 .. :-)
Old 01-28-2022, 08:54 AM
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Originally Posted by lavi rider View Post
Not busting balls here … but 2/7 = 1/3.75 …. Right .. 4/14 .. :-)
not busting balls here but....
2/7 = 1/3.5 not 1/3.75 😉
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Old 01-28-2022, 10:15 AM
  #28  
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Originally Posted by LGM Graphix View Post
not busting balls here but....
2/7 = 1/3.5 not 1/3.75 😉
correct ha ha ha !!!
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Old 01-28-2022, 10:59 AM
  #29  
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Don't worry Ron. In any case the end result will probably be too clean.
I will overspray it with epoxy primer and sand it smooth.
Old 01-29-2022, 02:32 AM
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While building airframe, parallel project was to figure out how to make landing gears. Mig-21 gears are far from simple, and even though scale is big, parts tend to be quite small.
After design process I printed parts and tested their function and fit. After great success there was time to materialize them in metal, part by part.

First iteration printed.

Testing fit and function.

Time to change plastic to metal.

Almost all parts in metal.

Before I started building main gears I built nose gear, which I thought to be like walk in the park. Well, it was not. Unfortunately I have not really pictures from that project.
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Old 01-29-2022, 05:54 AM
  #31  
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Great job on the mains!!
Old 01-29-2022, 08:01 AM
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It took some time to make all the parts and there is a lot of them. Even making those small axles took several evenings.


Links to operate wheel rotation.

Pretty much done.
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Old 01-29-2022, 08:24 AM
  #33  
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Those legs are a work of art! In fact the whole project is. Nice work.
Old 01-29-2022, 03:04 PM
  #34  
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Originally Posted by Kristola View Post
It took some time to make all the parts and there is a lot of them. Even making those small axles took several evenings.


Links to operate wheel rotation.

Pretty much done.
I would suggest doing a load analysis on those actuating arms ..
at that physical size I’m not sure if aluminum is up to the task as the preferred material to make them from .
it might turn out you’ll have to switch to a harder metal .
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Old 01-30-2022, 05:02 AM
  #35  
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You might be right.
Having simulated everything in my head and the question "will it survive", makes this hobby interesting.
Al7075 and steel have been used everywhere I think the load is greatest.

I took couple nose gear pictures and one from the elevator mechanism.


Nose rubber is 3D-printed and not yet glued.

There is oil damper inside the leg.

Elevator mechanism using ball bearings as links was joy to make.

Last edited by Kristola; 01-30-2022 at 05:04 AM.
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Old 04-03-2022, 07:21 AM
  #36  
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Brakes, rims, some wire harnesses, cabin locking mechanism etc. are done. Soon I spray some paint on.
13kg at this point. Still missing engine with it's accessories and all batteries. Some lead will be needed ti fix CG.

After 2.5 years work, it starts to feel like an ARF.
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Old 04-03-2022, 05:08 PM
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Looking nice! With that carbon weave, almost too nice to paint! 🤓
Old 07-07-2022, 03:53 PM
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Any updates on this beast of a project??
Old 07-08-2022, 04:59 AM
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Well Ron.... It has been primed white with acrylic filler and radio installation is about done.
Retract controller is tested (made by me), which need to be installed. All retract and radio wiring is done.

This weekend project is to install engine and it's stuff, and I hope to install fuel system too.

What is missing, is CG-calculations (once again to be sure) and batteries surrounded by lead.

After that it's not finished by any means (probably never is), but it is ready for it's first flight.

Well... Maybe some small things needs to be done...
Old 07-08-2022, 08:23 AM
  #40  
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You’re making good progress! 🤓👍
Old 08-08-2022, 11:20 AM
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I took vacation from work and was finally able to make maiden flight.
There was some rectract gear control issues, but long dark winter hours will solve those.



Maiden flight 7.8.2022
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Old 08-08-2022, 11:28 AM
  #42  
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Outstanding, congratulations on the first flight and a great looking airframe.

Regards,
Old 08-08-2022, 12:21 PM
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Wow, congratulations!! Looked very predictable in the air! 🙂 I’m sure you’ll resolve the gear issues.

Any idea what your (model) current weight is? Looks like a floater… 🙂
Old 08-08-2022, 01:44 PM
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Wow, that is way cool. Congrats on the first flights. What an achievement!
Keep us posted on progress.
Gary
Old 08-08-2022, 07:14 PM
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Outstanding approach and landing
Old 08-08-2022, 08:54 PM
  #46  
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I heard somebody comment on the low speed, during the video. And at the end: "Can't complain about the landing either".
Old 08-08-2022, 10:24 PM
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We need Hunkki approves -stickers! That looked almost too easy as for maiden glad there was atleast something to fix for the next one. I guess small class is too tight?
Exeptional work as always.
/Jyri
Old 08-09-2022, 10:02 AM
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very nice!!
Old 08-10-2022, 10:24 AM
  #49  
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Thanks

My goal was under 20kg and it is about that just now. I probably have to lose about 500g from the nose (there is 1.5kg lead and unnecessarily big batteries). Maybe more, if I update some of the rear parts. Some of the weight come back, when gear doors are implemented.

Just one flight done, but my thoughts about the capabilities of the plane are very positive.
I'm just designing a new retract electronics, using more like power electronics mind set this time.

II have told to my self that there was quite a lot off things that were working just like they were planned. That small gear control related hiccup will be sorted.
Figuring out CG was a bit painful, or more like can I trust my intuition (I had some lack of confidence). Thrust line was perfect, just like fuel system. Also control movements matched my hands.
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Old 08-10-2022, 12:18 PM
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Under 20kg is pretty impressive considering the scale.

Regards,

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