SR-71 90mm edf

chaos23

Senior Member
I origanaly started this build project as a balsa scratch build in the balsa builders thread SR-71 90mm edf , but quickly realized the cost of balsa and moved to 3D printing it instead.

So welcome the the first part of a journey that will take us to the end of 2015 and a first in RC 3D printed aircraft.


 

chaos23

Senior Member
working away at the engine nacelle got some renders for you all
persp1.gif

side1.gif

this one shows the different components
sr-71.0001.gif
 

SnowRocker88

Amateur pilot and builder
Modeling in SolidWorks? So, are you really prepared to pony up $4-5k for a carbon printer for this project? Either way, I'm in for progress!
 
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chaos23

Senior Member
im using Autodesk maya 2014, and ill be tailoring to the requirements of the part. ABS mostly but for other non structural parts ill use PLA for finer details. along with carbon fiber square tubes, round tubes and rods for the bulk of the strength. around 90% of the skin will be molded carbon fiber, the molds will also be printed in parts and put together for larger parts.
 

chaos23

Senior Member
yup, where i live anyway. the cost of just the balsa to build it i worked out to be over $2000 dollars including the cost of getting the forms and ribs laser cut. remember this is a 2.4m long plane im building. the printer is a long term investment for future projects so at the end of the day the cost will be in the plastic which is $30 to $40 bucks a Kg. consider that the goal weight is under 10kg its a fraction of the cost of balsa, plus being able to print my molds for the shell, again is a massive reduction of costs.

if you think of building planes in the current convention then yes you would assume it to be more expensive. however when you start seeing all the places where a printer eliminates costs by reducing the number of processes needed, it becomes cheaper. on top of that you can start almost inventing new methods to speed up and simplify the pipeline by shifting more of the work into the 3D modeling program.

i never said this would be cheap either way, i just worked out it would be cheaper in the long run to start making planes with a printer. the best bit is ill have a catalog of spare parts should something break or wear out, all at the push of a button.

hopefully the techniques and methods i use here will pioneer a new breed of rc plane builders.
 
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SnowRocker88

Amateur pilot and builder
im using Autodesk maya 2014, and ill be tailoring to the requirements of the part. ABS mostly but for other non structural parts ill use PLA for finer details. along with carbon fiber square tubes, round tubes and rods for the bulk of the strength. around 90% of the skin will be molded carbon fiber, the molds will also be printed in parts and put together for larger parts.

Okay, so you're not getting the crazy carbon printer? Lol
 

chaos23

Senior Member
Okay, so you're not getting the crazy carbon printer? Lol

one day maybe but its not needed for this job, most of the strength will be in the skin and CF spines. the CF printer would be good for extreme multirotors and stuff like that.
 

SnowRocker88

Amateur pilot and builder
It'd be awesome for everything really. I wonder if you could get similar results from just pushing a thread of CF out with the extruded material...hmmm.
 

chaos23

Senior Member
It'd be awesome for everything really. I wonder if you could get similar results from just pushing a thread of CF out with the extruded material...hmmm.

not realy, the strength of CF is in the CF and the resin, you put CF in a soft plastic it wont get much stronger, it will just flex further before breaking. that was the big hold up with that CF printer, the had to invent a new resin plastic that hardens like glass
 

SnowRocker88

Amateur pilot and builder
yes it did my friend, sorry for the leave of absence. ive re thought how im going to design this and moved away from using Maya. ive learnt to use a new 3D software called Inventor pro.

Very nice! I learned on Autodesk Inventor! This was way back in 2006 tho.