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Old Jan 28, 2010, 01:40 AM
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Joined Jul 2009
699 Posts
Awesome!

This is turning out pretty sharp! I hope your maiden goes well.

I would like to build my own EDF airliner one day. I've gotten the hang of flying EDF jets, but matching a power system to a custom build is still beyond my capabilities.

What do know of that might help you is a product made by Woodland Scenics called "Subterrain Foam Putty." It's a product model railroaders use when shaping foam landscape. The stuff is water based and can be sanded beautifully. It's light weight and is highly recommended.

I just used it to repair my Blue Angels Art-Tech F-18 in this "How To" video I did:
HOW TO: Foam EDF R/C Jet Crash Repair (Art Tech F-18) (9 min 39 sec)


Keep up the good work!
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Old Jan 28, 2010, 05:06 PM
Team 3DHS
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Nashville , Tennessee
Joined Jan 2009
5,479 Posts
Quote:
Originally Posted by AirChime View Post
This is turning out pretty sharp! I hope your maiden goes well.

I would like to build my own EDF airliner one day. I've gotten the hang of flying EDF jets, but matching a power system to a custom build is still beyond my capabilities.

What do know of that might help you is a product made by Woodland Scenics called "Subterrain Foam Putty." It's a product model railroaders use when shaping foam landscape. The stuff is water based and can be sanded beautifully. It's light weight and is highly recommended.

I just used it to repair my Blue Angels Art-Tech F-18 in this "How To" video I did: http://www.youtube.com/watch?v=10mRsTUEj-U

Keep up the good work!
Great video , I liked the hotwire cutter ... where did you get it ?
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Old Jan 28, 2010, 06:17 PM
HappyGoLucky
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Germany, BW, Ibach
Joined Dec 2009
543 Posts
@wamsy: Matching the power system to the custom build should not be that hart. I'm sure if you post a drawing and the projected wing-area and weight a lot of people in this forums will gladly help you with the power-system.
In my case, I simply took a pretty potent power-system to be on the save side.

Your repair is pretty astonishing. If I just saw the final repaired plane I would not have guessed it had a severe crash. I hope this foam-putty is for sale in a hobby-shop somewhere around here.

thanks for your video and cheers
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Old Jan 28, 2010, 11:34 PM
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Joined Jul 2009
699 Posts
Hi guys,

The foam cutter is by Woodland Scenics (same company as the foam putty), and their stuff is found at most model RR shops. If that doesn't work for you, there are a host of websites that sell their stuff, including the major distributor Walthers (www.walthers.com). You can order direct from their website if need be.

As for me wanting to tackle an airliner, I'd want to do a 727 similar to the one fabiofleal and neffwaffe did. I'd like mine to be a bit smaller to make transportation easier. I was thinking something like a 40mm or 50mm EDF size might be decent. The problem is I had no idea how much it would weigh or what the wing area would be. I'd want to build it around the EDFs.
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Old Feb 15, 2010, 08:05 PM
Airliners lover
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Brazil
Joined May 2006
177 Posts
AirChime,
Power-to-weight versus size is the biggest dillema to build any airliner from scratch. Big sizes mean lower wingloads as the weight doesn't increases as fast the size does.

Therefore, if you want to make it smaller, you'll either compromise the scale or the craftsmanship of your plane. my 727 for example, is still missing the blue paint on it's belly as I cannot use vinyl due to weight constraints.

Keep in mind that Your plane's weight will always start from the hardware weight, which is usually about 0.5kg for a twin EDF typical setup. You'll have to play a little w/ the strengh of the materials and apply some of these engineering principles to manage the impact energy as well such as leaving part of the strenght to the fuselage skin or building it w/ a balsa spine structure.

To build a 727 is challenging just because of the scale (engines X fuselage). The best balance between durability and performace I could find was GWS EDF55+4S+heatsinks. Total Current draw at full throttle is about 38 amps. So, the smallest battery tht's suitable to give you a good flying time is a 30C 4S which weights about 270g.

Therefore, a reasonable thumb rule to build an airliner from scracth would be:
Check the weight of your hardware
Double it. It's a good estimate of the final RTF weight. If the total thrust provided by your hardware is less than 55% of the estimated weight, revise the hardware choice.
Divide this final weight by a number equivalent to a 30 to 40g/dm2 (each dm2 equals to 16 square inches) wing load for a wingspan up to 50 inches and up to 55g/dm2 for a wingspan up to 80 inches. This division will give you the required wing area.
Given the required wing area, you can calculate based on some high school geometry knowledge, the wingspan needed. It's an iterative process. I recommend to make an excel sheet w/ all the formulas and dimensions to speed it up.

But be careful: Wives use to hate this process because of the time it takes. I often use to get squeezed between my wife and my job ("car maker") to find some time to do it.

Regards from Brazil.
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Old Feb 16, 2010, 08:18 PM
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Thanks Fabio. I'm not sure I'll end up with the time to do such a project any time soon, but man I'd love to! I hope there are some updates on this MD-80 soon!
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Old Apr 14, 2010, 01:12 PM
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United States, SC, Charleston
Joined Mar 2007
16,169 Posts
Excellent build Chochmah! What airline is your MD-80 going to be? I can't waist to see her fly!
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Old Apr 15, 2010, 03:40 PM
HappyGoLucky
chochmah's Avatar
Germany, BW, Ibach
Joined Dec 2009
543 Posts
It's going to be no specific airline for the maiden. I run out of spraypaint and the Acrylpaint does not look very nice on the EPP.

Finger crossed for Saturday I'm rather nervous already.
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Old Apr 15, 2010, 06:10 PM
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Good luck! Try and get video.
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Old Apr 16, 2010, 12:50 AM
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Nevada, USA
Joined Sep 2007
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looking forward to a successful report!
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Old Apr 16, 2010, 03:29 AM
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nøtterøy, NORWAY
Joined Mar 2006
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good luck
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Old Apr 16, 2010, 08:37 AM
HappyGoLucky
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Germany, BW, Ibach
Joined Dec 2009
543 Posts
Servo glitching

This is getting slightly frustrating. I charged the batteries for tomorrow and did a radio check. As soon as I plugged the charged batteries in the right aileron startet moving violently up and down for 5 seconds then turned downwards almost 90 deg. and kept trembling. The left Aileron did not show any unwanted behaviour.
When I move the Aileron-Stick on the Radio the left Aileron worked perfectly and the right does react to input but shivers and does large movements every three seconds.

I changed the channel in the receiver and switched the Plugs of the two Aileron Servo Connectors to the Y-Connector but that did not change anything so I reckon it must be the Servo.

Please Advise if there is anything I can do to repair the Servo or if I have to order new ones.
(This RC-Stuff seems to be pretty rubbish, that would be the second servo giving up on me besides the Receiver where the Antenna fell off and I haven't even done anything with it yet... )

ps. it is this Servo here: http://stores.servosandstuff.com/-st...rvo/Detail.bok
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Old Apr 16, 2010, 09:51 AM
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Nevada, USA
Joined Sep 2007
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It could be the servo or if the same rx that antenna that fell off if it was not repaired correctly.
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Old Apr 16, 2010, 03:50 PM
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massachusetts
Joined Oct 2008
7 Posts
Very interesting build up technique. You say you are new and have never done this before? Look forward to flight video
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Old Apr 17, 2010, 03:47 AM
Go FASST or go home...
Ben_E's Avatar
Bergen, Norway
Joined Nov 2002
3,149 Posts
Just to inspire you guys a bit...

Hawaiian Airlines 717 (4 min 0 sec)
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