50% Extra 300 scratch built
 

I am scratch building a 50% 300 from Carden plans that I blew up 118% I have posted this build on another sight and I was wondering if there was a interest here on this site? I am no plane designer or engineer I have a passion for large airplanes and anything that presents a challenge. The challenge here is to get the plane built under 55lbs ready to fly. It will be powered with a 3-W 275 competition version. I have requested help from others to help me achieve this goal. Everyones ideas are welcome. I have spent almost a month on the motorbox so far and it has come out well. We had a goal weight for the motorbox of 2.5 lbs and we got 1lb 15oz I am going to add more weight to the motorbox for bracing as I have allowed 2 1/2 lbs for it. This is a journey that hopefully will help everyone learn a little something. If there is interest here I will take the time to keep this site up to date.
Thanks
Mike Chandley

RE: 50% Extra 300 scratch built
 

Here are some pics of the motorbox.

RE: 50% Extra 300 scratch built
 

Wicked stuff, Mike! I would definitely follow a build thread on this monster.

I am not into really big stuff (a G-62 is a really big engine by my standards), but anything creative and out of the ordinary is always interesting to read about. Why don't you post some proposed specs and construction methods for our enlightenment and comment?


Mark

RE: 50% Extra 300 scratch built
 

G62 I thought a 26cc aeroplane was big looking forward to seeing how this is contructed
What is the wingspan and what sort of props would be used to fly it through manoeuvres

RE: 50% Extra 300 scratch built
 

The motorbox was constructed of 1/4" thick pieces of Dow 40 foam with 4 layers of .007 carbon fiber laid bidirectional for strength in 90 and 45 degrees. We cut the foam on a cnc router that my friend Mark McClellen built. Mark is a Big help in this build as you will see. Mark showed me how to draw in autocad and I spent about 1 week drawing the first design of the motorbox. We cut the box out two times in 1/8 lite ply to check the changes and adjust the fit of the parts. With the help of others we changed a few things we didn't like about the design of the motorbox. I went back to drawing and changing things till we came up with the new design. The landing gear plate and the firewall are constructed of foam, 5 ply 1/8 ply, and 4 layers of .011 carbon laid bidirectional.

RE: 50% Extra 300 scratch built
 

Sorry,
In the landing gear and firewall there is 6 layers of .011 carbon laid bidirectional.Two layers on the outside two in the middle and two on the other side. I used the ply to give it strength where the bolts go through.

RE: 50% Extra 300 scratch built
 

For the ones that wanted to follow this thread there is another thread on a different airplane site called Git-r-Done Giant scale I do not want to get out of line here so you will have to search for 50% 300 Extra.
I do not know if it is ok to post the other web site. I have about 450 replies and alot more detaled info there.
Thanks hope I am not out of line.
Mike