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Foam Ultralight Scratch Build

#1
Hey guys recently I was trying to watch all of the episodes in one weekend (it didn't work out ;-() but anyways sand I saw the bricksler episode and I am avid fan of ultralights (fyi for anyone that doesn't know an ultralight is an plane that weighs less than 256 lbs and does not require a license to fly) and was thinking about buying a kit until I saw the bricksler episode and I thought would it be possible to essentially double it and create an ultralight aircraft (of course after flying it as an RC model first) so I did a bit more research and thought that the first thing that needed to be changed was the under camber airfoil and replaced by stacking up the 3/4 inch foam up into a block and cutting with a giant hot wire cutter. Of course instead of the foam fuselage I plan on replacing it with a a lawn chair for the cockpit and a 2x2 a4 aluminum tail. I highly doubt that ill ever fly in this but it sure is hell goin be fun doing fpv and scaring the hell out of the neighbors!!! Here is the link to the bricksler http://m.youtube.com/watch?v=bns5x4pvl5Y
And the link to the motors http://www.hobbyking.com/hobbyking/store/__22036__NTM_Prop_Drive_50_60_270KV_2400W.html
P.S. I am going to brace the wings with aluminum A4 tubes (every project I ever do somehow gets mixed up with A4 as I like to call it;-)
Thanks
Wjionieis
 

earthsciteach

Moderator
Moderator
#2
Before you go down a very deadly road, take a look at an ultralight that is built in much the same way, was designed by a Cessna engineer and has an impeccable safety record, the Sky Pup: http://machnone.com

If you know what you are doing and are very confident in your design abilities, including structural analysis, then go for it!
 
#4
Hahaha yea I saw that one too the only thing I have a question on is that if I use a hot wire cutter instead of a under camber wing will it affect the performance (less or more speed?)
 

pgerts

Old age member
Mentor
#5
Hahaha yea I saw that one too the only thing I have a question on is that if I use a hot wire cutter instead of a under camber wing will it affect the performance (less or more speed?)
What is the question? Make a scetch.
You can make any camber or profile with a hot wire. You dont need a giant hot wire. Make smaller sections of 3 or 4 ft and glue them together. I do not understand why you would use 3/4" foam if you are going to make a bigger plane.
Under camber is normally better for lower speeds.
 

robschonk

Senior Member
#6
Uhhhhh.....not a real good idea. Stick with a proven design like a Challenger or a CGS Hawk.

See my Challenger I w/477 in my avatar. Used to scare the he77 out of me from time to time, and after losing a couple of flying buddies, I decided to give it up.

Gorilla glue and CA work great on foam, not so much on human bodies.
 

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#7
I am working on a sketch and robschonk like I said I highly doubt that I will ever fly in this thing I probably will only fly a handful of times also pgerts I have a stack of 3/4 inch foam laying around in my garage because a job went bad and some how I ended up with it now I am thinking that I can put it to good use.
 
#9
thank you so much that explains a lot of questions of course there is still a couple unanswered, my first question is can flitetest of someone give a link to "blueprint" for the airfoil (something that I can print and then cut into a piece of plywood) because I know that I can probally come with something that will work fine but fine isn't good enough for something that can be used to lift 160+ pounds. My second question is what is the best type of wire for hot-wire cutters I use guitar wire of some piece of junk that I found in the garbage but it doesn't cut as smooth as I would like it to and it isn't long enough.
P.S. I am working on a sketch (well at least trying) because my sketch up wont work so i may have to go 2d and draw it and then copy it.