Plane Frame Model Via C.N.C..(1st Trial)

I have been working on the design and manufacture of the frame of a U.A.V for quite a while now i.e since late August and i was able to make some good progress although i have to admit that the pace has been quite slow due to a number of unavoidable circumstances added on to the fact that i had to attend my summer internship at a manufacturing company that specializes in CAD/CAM known as Numerical Machining Complex where i worked long hours ,luckily i gained a wealth of knowledge and insight into a wide variety of the various aspects of design and manufacturing ,which adding onto all that i learned during the Localized Design and Manufacturing workshop at the University of Nairobi’s Science and Technology park under the stewardship of Miss Ella Peinovich and Mr. Tom Odoyo ,will prove  to be invaluable and the hands on experience gained from being in the varied design environments of both the design workshop and the summer internship will hopefully be the missing link i need to enable my projects and ideas to come to life and hopefully take up a life of their own.

Enough of that now.

I started the entire visualization process by designing a model glider on Rhino which is a 3D modelling and design software and came up with the below image.I paid as much attention to the aerodynamics and proportion as i could but i made sure not to ‘over-design’ it.I wasn’t able to render the image mainly because my rhino evaluation had expired by the time i finished the exterior design.I’ll be sure to do so in my next design.

I then designed the frame of the glider/plane based on the initial exterior design but i had to scale some parts up in relation to others and vise versa, mainly due to the fact that the milling machine i would use to cut the frame (the Shop Bot) couldn’t cut small pieces of the material i had available because the smallest available bits were roughly 0.125 inches in diameter.

The frame/bilateral grid varied from the initial design but i assume when i’ll be done with everything and i put some cladding on the frame everything will come back to the initial design except for the scaling .

I tried playing around with the color for presentation purposes but decided to stick with the original because the others were too loud.

After designing the frame i isolated the individual parts and prepared them for milling sadly i didn’t take any pictures of the preparation but i’ll be sure to cover all that in all subsequent designs.

I exported my prepared files from rhino and cut all the required pieces needed for the final assembly on the Shop Bot at the Fab Lab Nairobi .I used boards of ply wood of varying thickness i.e 0.5 inches and 0.8inches solely due to its availability and that brought about some problems that will be noted in the wing assembly images but i will try and correct then using some glue to fill the spaces and some PTFE tape to hide  the glue which you will see in my next blog post.

I finished cutting all the pieces and laid them down in their pre-assembly state so as to get an idea of what the final assembly would look like.

I took another picture from the top view for documentation purposes and to give you another view of what i’m trying to achieve here.Hope you don’t mind the odd looking shoe.

I then laid down the parts of the wing after cleaning them and removing some of the sharp edges to make them more practical as i prepared them for the wing assembly.

Another picture as as i played with the wing parts before assembly,note the airfoil shape i managed to generate for them,this brought about one of the challenges due to scaling issues and i ran out of material after cutting all the pieces for both wings so i had to use a thinner board of 0.5 inches which brought about assembly problems as noted earlier. 

I started gluing the individual parts to their respective notches on the first connecting rod of the wing frame using super glue because the parts were too thin for me to nail together and the plywood would fracture if subjected to repeated hammering.

I then laid down and glued the second wing  piece to connecting rod.

I then laid down and glued the third piece in place and tested their rigidity and if the glue had settled by shaking the assembly vigorously .

After gluing the three pieces to the 1st connecting rod ,i put in the 2nd connecting rod and glued it to the notches on the  wing parts and came up with the image below.I also shook this assembly to see if the glue had settled well.

I took another picture of the wing assembly so far from a different view.

I repeated the whole assembly procedure for the other side of the wing and it looked exactly the same so i didn’t put up any pictures of that.

The only remaining thing now is to join the wing assemblies to the frame and to add the cladding material and the 1st trial of the model plane frame will be ready for display and i’ll be able to start work on the 2nd model which if all goes well will take to the skies if i can get some balsa wood or dense styrofoam that i can  cut on the Shop bot.

Thank you for your time n look out for part 2.

An audio-visual presentation.

we cut out all the parts of our model plane using the laser cutter and here are a few of the images.

we had a small problem with the notches,(they were too small ),so we had to use a “wembe” (razor blade) to increase the size to accomodate the

thickness of the ribs.


then we went ahead to assemble it and threw in a motor,propeller and batteries to be able to explain our concept further.

Plane final day presentation.

We thought of taking it back and coming up with a plane design similar to that of the wright brothers,so this is how we started out.

then we went ahead to design the desired wings.

then we designed the bilateral grid.

after that we worked on the cover of the plane.

here we have the final covering.

and finally the plane .

the final product varied from the original concept due to a number of issues that we had overlooked such as:

the thickness of material.

the scale of the plane in the initial design was not exactly practical , for we had intended to cut using ply-wood initially but the scale was too small for us to cut out on the C.N.C  so we decide to use mat board instead.

the positioning and width of the notches turned out to be a problem during the assembly because of a wrong assumption we had mad earlier based on the laser cutter.

most of all the time constraint,we worked on everything in a very short period.