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Nov 16, 2019, 03:36 PM
A.K.A sir Crashalot
methuso's Avatar
ah ok.
yes i know you did not. was just wanting some input before i get my thumbs out

thank you for input
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Nov 16, 2019, 03:49 PM
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for light projects, it is better to use 1 micron film, significant weight reduction
Nov 16, 2019, 05:44 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
Hi Ruslan,
Thanks for the info on covering. I wondered if you had used thinner film on your plane below. That one was 300mm span (about 11.8 inch), so a bit smaller than mine at 13 inches. I still consider your weight of 1.22g with the fuselage bracing and landing gear pretty amazing.

I did calculate the weight savings from using 1um film (1.3g per sq.meter), and OS Film (0.7g per square meter) compared to 2um film (2.2g sq.meter). Since I knew the square inches before starting to mold CF or cover I calculated the weight savings from going to 1um. It would save less 0.08g {noted in posts #11 to #13 above} compared to the 2um film. The smaller the plane the less the savings from going to a lighter film since there is less area.

I also consulted with my friend Ray Harlan, who sells the 1um film, and he recommended against it. He said it is so delicate that it gets holes and is damaged very easily. He did use the 1um film on his plane and wishes he had used 2um. I also knew that I wanted to use the Oramask material for painting masks. I was pretty sure that the 1um film would tear and not stand up to the Oramask being peeled off. My experience with it and the 2um film confirms that. So, in the end after going back and forth I decided that the less than 0.08g weight savings was not significant enough. I'm not any where near as good an airbrush artist as you are. So, I use templates, where you do them free hand (I think).

Did you ever get equipment in your "thistle" plane in the picture below and fly it? I'm curious how it stood up to being flown on a regular basis. That was a consideration as well. I want to fly this plane and have it stand up to frequent and regular flying. So, that was another reason I went with 2um film.

I do know that my airbrushing is still heavy compared to what you do. The total weighed added from painting on this plane is 0.31g. And, I am sure it could be even lighter if I could airbrush like you do.
Last edited by Gordon Johnson; Nov 18, 2019 at 10:18 AM.
Nov 17, 2019, 04:17 AM
Registered User
this 500mm aircraft is also covered with 1 micron film, if you fly instead of banging on the walls, there will be no holes in the film
Nov 17, 2019, 11:20 AM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
I think what Ray's plane has had is what is called "hangar rash", from handling, moving, removing and reinstalling equipment etc. Not from banging into walls.

I am nowhere as good at this CF construction as you are. This is only my fourth CF plane, and second of this F3P style of construction. I think you have done many many more than four. The graphics are fairly complicated when using painting masks, which I have to use because I'm not good enough at airbrushing to make them any other way. The checkerboard pattern was a pain, and resulted in Mylar tearing on an early version when removing the Oramask. This would have been even more of a problem with 1 micron film. So, for all these reasons, but mostly due to the fact that I'm not as good at this as you are, I made the conscious decision to not use 1 micron film on this plane. Given my modeling inadequacies the 0.09g weight savings didn't seem worth it at this stage in my process of learning to make CF planes. Maybe I will give it a try on a later plane.

Your planes are exquisite works of arts that the rest of us can probably only aspire to. What I am doing is documenting the steps I'm going through to build this plane (and my earlier CF planes) in the hope that it will help others to take the plunge and try one of these molded CF planes. By showing the steps, rather than just completed planes, I hope this will prove useful to any people who also decide to give this type of plane and construction a try.

For what it is worth, my Yellow 20 inch Carbon Bender has never hit a wall. I'm a better pilot than that.
Last edited by Gordon Johnson; Nov 17, 2019 at 01:02 PM.
Nov 17, 2019, 01:36 PM
Registered User
if you use car acrylic paints-base, nitro-base, they dry quickly, very quickly in 2-3 seconds, stencils can be made of thick paper or foam 1-3mm
Nov 17, 2019, 10:20 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
thanks for the paint info. If I can find that kind of paint and thinner in small quantities I may try that on a later plane. I'm currently using Creatix water based paint.
Nov 17, 2019, 10:23 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
On to hardware. My plan is to build the plane upside down, and not put any of the cross bracing on the lower fuselage until after I have 100% of the equipment installed. This will make routing wires, push rods, etc much easier without the cross bracing in the way.

So, first the drive. This is Ruslan's (29rus) amazing super micro coax drive with approximately 6-inch diameter foam props. It weighs 1.8g including the props.
Nov 17, 2019, 10:29 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
for the ESC I have some choices. At the far left is the Micro Invent (not in business any more) smallest ESC the MBC1, which is just 0.18g bare with no wires. In the past when I used it on my skeleton foam Air Bender with a Gasparin BL motor I was not happy with how it behaved at low throttle. The throttle would go from about 40% to zero in one step. Next to that is the MBC2, but a bit heavier, but still only for 1-cell use. After that is the MBC4-B, with can handle 1 or 2 cells. It's still light, but a bit heavier. After that is one from the French firm Micro Planes Solutions (not in business any more). This one is pretty light, and can handle 1 or 2 cells. And, last is what is currently available, the HK 1-cell ESC.

The ESC's for micro motors that I have found had the smoothest startup and best throttle at low settings were the Heino Yung YGE4 and also the Micro Planes Solutions ESC (but the MPS were a bit lighter than the Heino Yung). I also found there are differences in efficiency for different ESC’s due to software as well as hardware differences.

So, I have some testing to do. I want to see how the MBC1 and MBC2 work with the Ermolin Coax drive. I want to see if they behave well at low throttle settings. My goal is to use the lightest ESC that also performs well.
Last edited by Gordon Johnson; Nov 18, 2019 at 10:07 AM.
Nov 17, 2019, 10:30 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
So, time to get out my static test rig, make an adapter for the Coax drive, and solder up the connections so I can monitor amp draw, volts, and thrust very precisely.
Last edited by Gordon Johnson; Nov 18, 2019 at 08:07 AM.
Nov 17, 2019, 10:36 PM
Senior to who? Member
crossup's Avatar
I think what Ruslan is referring to is acrylic lacquer, VOC considerations is making it hard to find and its not even legal to apply it to cars in some states for that reason.
Nov 17, 2019, 10:43 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
There is also the choice of batteries. At the left is a Hyperion 70mAh cell with UMX plug. Next to that an Ares 50mAh cell, and at the far right a Zippy 50mAh cell which has had a UMX plug installed.

The other attachment is a discharge test at 0.60 amps (12C) of the Ares and the Zippy cells. The Ares is clearly inferior. At this point I think I will be using the Zippy. But, static tests of the Coax drive will verify what its amp draw is and if I can use the 50mAh cell instead of the heavier 70mAh cell.
Last edited by Gordon Johnson; Nov 19, 2019 at 10:26 PM.
Nov 17, 2019, 10:47 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
Servos will be one of the Micro Flier Radio 0.50g servos (at the left) for the ailerons. And, for the rudder and elevator two of the Micro Flier Radio 0.40g servos, which have 1/3 the torque of the 0.50g servo.
Nov 17, 2019, 10:49 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
Receiver will be a Deltang RX31C
Last edited by Gordon Johnson; Nov 18, 2019 at 12:18 AM.
Nov 17, 2019, 10:50 PM
in pursuit of low wing loading
Gordon Johnson's Avatar
Thread OP
Quote:
Originally Posted by crossup
I think what Ruslan is referring to is acrylic lacquer, VOC considerations is making it hard to find and its not even legal to apply it to cars in some states for that reason.
Hmm. I had also wondered if it would make too much fumes for using in my basement workshop. I can't use stuff with a lot of fumes or it smells up the entire house. And, if it's getting hard find then it may not be an alternative for me. Thanks.


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