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Oct 28, 2020, 10:32 AM
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Hello guys, thx a lot to both of you for your suggestions and motivation to improve this build! I try to incorporate your points into this build as possible or consider them in my next one.
The airfoil, I cant to apply now, the wings are more or less done, but definitely, by watching your videos, I can confirm that it flies nice and fast! (BTW your Beta is nice, try to see a my)
Because the new EDF is still pending with delivery, I can do just a front part of the fuselage and drawing on the paper a possible solution for the air-intake. So, the idea is simple, I will cut a corner of the wing close a fuselage till the main spar, plus make a hole to the side of the fuselage, by this approach I hope I will increase the cross-section.
Another challenge, both of you are skilled with EDF, could you recommend an optimum ratio for the output cross-section size area compare to 70mm EDF?
Slowly ahead :-)
Vasek
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Oct 28, 2020, 10:47 AM
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Quote:
Originally Posted by Beatnik
This is the L-29 we designed and built. Dimensions 1130 x 1070 mm. Made from foam, by CNC cut. The air intakes are replica, a hole is installed for air access from the bottom of the fuselage. Impeller 70mm, battery 3300mA 4s. The plane flew well, as a training one, as for me it is rather slow. Then they installed non-retractable landing gear.
Profile was original. The engine nozzle has been slightly enlarged.
XXXXX

Hi Beatnik, thx for your message, I have already studied your thread, this was one of my reasons to start with this amazing plane. Your size and setup are similar. I hope that my will flies like yours.
Vasek
Oct 28, 2020, 10:58 AM
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@Von W, @ Beatnik, Yeah, CNC cutting is something I'm interested in, I just haven't had the guts to try it sometimes and I don't know anyone who uses it. Can you say anything more about your CNCs?
thank you
Oct 28, 2020, 01:31 PM
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Podnebesny's Avatar

Cnc foam cutter


Hello everybody, my cnc foam cutting machine looks like this:
Oct 28, 2020, 01:33 PM
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Podnebesny's Avatar
stepper motor X axis
Oct 28, 2020, 01:35 PM
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Podnebesny's Avatar
wire heating unit, power unit and controller
Oct 28, 2020, 01:37 PM
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Podnebesny's Avatar
wire tension system, Y and A-tower
Oct 28, 2020, 01:40 PM
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Podnebesny's Avatar
This machine deserves separate thread, I believe soon I`l made it
Oct 28, 2020, 01:50 PM
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Podnebesny's Avatar
Dolphin was the first airplane model made in collaboration with Beatnik.
Beatnik made initial 3d design, assembling and finishing, I cut xps parts and a sympathetic
Oct 28, 2020, 06:45 PM
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Nice work
Latest blog entry: In flight
Oct 29, 2020, 12:55 AM
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@ Podnebesny,
Your machine looks good, very compact and very different from my cutter.
Oct 29, 2020, 01:46 AM
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Here as requested then a little more about my cutter. From the mid-ninties I already build many models from foam, then still like you do with the help of templates and cut by hand. Ever since then I dreamed of a CNC foam cutter. It had to happen at the end of 2012, after hours of sketching and thinking I started on it. The machine had to be simple and build without exotic parts. I then bought software and control and immediately the machine worked reasonably well, after a few minor adjustments it went smoothly. There was sometimes some wear on the threaded rods here and there, but the cutter worked for hundreds of hours five year long without much trouble.
Because I wanted to keep it all as simple as possible, I did not provide a tensioning system for the wire and I work with a simple bow that rests in a V-cut on each axis.
In the meantime my second machine has been working for almost 3 years.
The first was since I didn't have a CNC router cut out of plywood by hand at the time. The problem was that no matter how accurately you work, it will never be as perfect by hand as with a CNC machine. At the end of 2017 I thought it was time to make a new machine, in the meantime I already had a CNC router and 3D printer so this time it had to be better. I kept the principle of the machine that had already proven its worth. I did switch to a belt drive for the X-axis and a trapezoidal threaded rod on the Y-axis, which is the big difference with the first machine. The only thing I have to replace every now and then is the wire, this also because of my own stupidities ;-). I think that happens once or twice a year and it is certainly not the case that I only cut a few times a year, it is very rare that the machine is not used for more than a week.
The dimensions of my machine. The two axles are 66cm apart, so the standard foam plates of 1250x60cm fit without any problems. I could also widen my first machine to cut longer pieces to almost 1 meter. But after a while that option was no longer used so I now have it fixed at 66cm. Height is approximately 40 cm and the depth to almost 90 cm.

And now some pictures, and a video of my first machine when it was brand new, this was one of my first trials
How to build a Radial engine (4 min 40 sec)
Oct 29, 2020, 03:12 AM
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Thread OP
Beautiful, you're both skillful, I have neither the means nor the knowledge to build my own. I'm looking for a commercial reference to a modeling thread in the Czech. I'm learning to draw slowly, that's a challenge for me too :-) LINK HERE the cost is about 300
Oct 30, 2020, 07:17 AM
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Beatnik's Avatar
It was so long ago that I forgot that there is a topic with a description of my L-29

https://www.rcgroups.com/forums/show...9-Dolphin-70mm
Nov 01, 2020, 09:26 AM
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Thread OP

The progress report


I am preparing the midsection of the fuselage with wing attachment. The front part of the wings holder has a place for the air-intake, in the backside down I made a space for bypass air intake when will be needed, but only at the wood part yet. Vasek


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