Build attempt / learning process

[AndyB]

Is this a good place for a build log, or should it be in a different section?

I've started to build a monster, and have had some good results, well good enough to share.

[billscottni]

If the monster is a slope model this is fine

[AndyB]

It's definitely for the slope.

This is all a bit new to me, technique and materials so it is not perfect, but highly enjoyable.

I started by cutting out the fuselage profiles and then using a hotwire to get the rough shape. I then drilled some rods into either end to add strength and make a sort of rotisserie arrangement for later. Filed the rough shape further and then sanded.

[AndyB]

For the vertical stabilizer (and eventually all other surfaces) I made a 4axis hot wire cutter and got to work. it was a bit tricky because of the root and tip difference in size and the length of it the kerf (hotwire burning size) took some attempts to get spot on. Anyway got that mounted and faired it in.

[AndyB]

I added some filler all over as there were some gaps in the foam, and faired again. Then covered it in lovely brown packing tape to create a barrier for the next stage.

[AndyB]

Next was wax and then two layers of glass weave, resin and peel ply. then bag it all up and let sit for 12hrs. Then another two layers of glass, resin and peel ply. some wrinkles on the compound curves, but all in all it was pretty neat.  To finish it off I unbagged it and tried to get it as hot as I could for the next 24 hrs. I didnt remove the peel ply until it had cooled back down because of the risk of delamination.

[AndyB]

Finally, I marked up the hatch, cut it out and poured in some acetone. With a bit of poking and pulling the packing tape detached and came right out without any messing. Was actually really surprised as I was expecting this to be a quite tedious and messy.

[rogallo]

A Jart,
     a very fast model and quiet a bit of history. I have a "kit" for an epp one, if anyone wants it.

The lost foam method is sweet and not bad for the second or third build.

Keep up the posting and the good work

Ralph

[AndyB]

Yea Ralph,

I'm wondering how I will ever land it. Actually thinking of the wings ATM and whether to not go will full wing ailerons and split into flaps and ailerons.

Another question I have is how to finish a balsa laminate, how to seal it for finish and paint?

[rogallo]

Full wing aileron, can use them as flaps on landing would be my preference.

Bill Scott is the man to give you advice on the finish for the wing, Are you planing on film or glass and paint?


Keep up the good work


Ralph

[AndyB]

Full wing aileron sounds nice and simple to me, just wanted to check as I saw some other builds adding flaps. I can always try it at another stage when I get more comfortable with the process.

re the balsa finish, I have no idea. It doesn't seem like it needs the strength of glass, but it would definitely make a nice finish if I used mylar when bagging it.

I did a test stabiliser; foam core and 0.8mm balsa skin, with a kevlar live hinge and some carbon tow and its really strong. I would prob not use this one as the finished product as I got PU glue on the hinge line and wasn't too happy with the opening to free it up, But this is all learning and testing to me.

BTW also bagged for this process.

[billscottni]

If you have the ability to bag the best finish would be lightweight glass cloth (25gsm). It's only to give you a surface to paint won't add much strength or weight
For landing you could set up full span ailerons as spoilerons which I believe is what John Pearson uses on his PSS stuff

[AndyB]

Bill,

Would that be on top of the balsa or instead of the balsa?

[billscottni]

on top

[billscottni]

Lots of good stuff here: https://www.youtube.com/user/evanevshaw/videos