I want to print a C-130 Hercules for remote control flight

[schafe 3]

Still moving along. Nothing picture worthy. However spring is here and the outdoors call. Still printing parts - slowly. Replacement parts might be here next week then it should go faster.

If this works, I've already decided what planes to make next. I have a 90mm ducted fan that I am going to build an EA-6B Prowler around. Not the most exciting plane, but I have a friend who flew 2nd seat in one. Additionally, you see all sorts of F-16s and F-4s. You never ever see an RC EA-6B.

Next will be a Tupolev TU-95 Bear. Once again a plane that no one else will be flying.

I'm a cronic project starter. There are lots of projects around my house that I have never finished. A psychologist could tell you this is a sign of something. I will finish the C-130.

 

[schafe 3]

Good news, bad news.

Good:

- Today I traced a bulkhead I had printed onto 1/8 inch hobby plywood and cut it out. (1/8 plywood is the standard material for creating bulkheads in large RC planes.) The plywood measures 3.1mm thick. The part I printed measures 2.6mm. (I chose 2.6 because it seemed "about right.") The printed bulkhead was in ABS and weighed 9.78g. The plywood weighed 14.69g. Converting the weight of ABS to PLA gives 11.64g for PLA. The printed part has .4mm top/bottom thickness, .8mm shell thickness and 20% infill. The printed part is not nearly as strong as the plywood, but a bulkhead's function is to create the shape for gluing balsa to, not providing strength. This is good since I am very concerned about the finished weight of the plane.

- I had previously machined the main landing gear out of aluminum. I have redesigned the LG to be incorporated into the printed sections of the plane. This results in less overall material, and that material is lighter.

- I am almost finished printing parts for the plane.

Bad:

- Today I traced a wing rib I had printed onto 1/8 inch balsa wood and cut it out. (1/8 balsa is the standard material for creating ribs in RC planes.) The balsa measures 3.3mm thick. The rib I printed is also 2.6mm. The printed rib was in PLA and weighed 9.63g. The balsa weighed 1.4g. Converting the weight of PLA to ABS gives 8.1g for ABS. The printed part has the same top/bottom, shell and infill values. The printed part is about as strong as the balsa. This is VERY bad since I am concerned about the finished weight of the plane.

- Although I am almost finished printing parts, I am no where near finished with the entire plane.

- I had to modify a part I had already printed and glued in place. Stay tuned to see if acetone works well for dissolving CA glue and to find out if it attacks carbon fiber. (A quick internet search gives mixed opinions on acetone vs carbon fiber)

I will have to make the majority of the wing ribs out of balsa to save weight. This project isn't turning out the way I originally intended - a 100% printed RC plane. I don't think it will be magazine worthy. No island for me.

 

[skint 61]

Keep going Schafe!! Your project is starting to take off

For info, I used some acetone on a carbon fibre piece and it left the surface quite messy. Didn't interfere with the strength of the part so much, but it didn't look pretty. My kit building skills may of been the major culprit though!

 

[schafe 3]

Acetone vs carbon fiber arrow - no problem. It did remove the glossy finish. I soaked the part in acetone for less than a minute to try and soften the CA glue.

Acetone vs CA glue - I did not notice any change. After soaking in the acetone the glue was as strong as ever. I had to pry, cut, twist and cuss to remove the section I had glued in place. The arrows held up very well against this abuse.

Tonight I cut apart an extrusion test cylinder to compare the weight of 1 thickness of PLA to 1/16 inch balsa. The section of cylinder measured .42mm thick. I cut a section of balsa the same size as the cylinder section. The balsa measures 1.64mm thick. The cylinder section weighed .61g and the balsa weighed .39g. The balsa is much stronger.

Tonight's conclusion is there is a reason RC planes are made from balsa. I have seen the videos of printed RC planes flying so I know it can work. If you have enough power you can fly an anvil. I'm trying to keep things as light as possible.

 

[gr5 2,172]

Maybe you should have bought a laser cutter instead of a 3d printer?

 

[schafe 3]

Yep. I know that people use basically the same process I did and cut out the bulkheads and ribs. But wait - isn't one of the features of 3D printing limited waste?

Laser cutter mod for the UM2 anyone? It has been suggested. I want one.

 

[jonnybischof 60]

If you want to pay for the laser tube (and power supply / regulation), which makes 80% of a laser cutter's cost, then you're good to go

And you have to do something with the build platform I guess. You don't want to cut through your heated bed

So, in the end, you'd probably end up building a whole new lasercutter instead of putting it into the UM..

 

[schafe 3]

Hi!! Remember me?? Summer is for flying RC not building RC. Winter is almost here and I am about to continue my C-130 project after doing basically nothing to it for several months.

If you go back through this topic there is a photo of the nose I printed. I am still very concerned about weight. I had what seems like a great idea - vacuform pieces over the printed parts. I made all the stuff for vacuforming and tried to make a new/lighter nose. I know, I'm trying something pretty complicated which I still think no one has done yet. Why not make it even harder? (Tip: Using your kitchen oven to soften the plastic results in a stink your wife will not approve of.) Without any more delay here is my first result:

 

 

I know the plastic is hot, but I didn't think it would transfer enough heat to soften the printed part. The plastic did not melt into the PLA which is nice. When I cut away the plastic it separated easily from the PLA. My next plan is to fill the nose with plaster.

 

Hey, Edison didn't get it right the first time either . . .

 

[schafe 3]

Still moving along.

The control surfaces are all installed. All of the printed parts are shown except the main gear doors. As shown here it is very tail heavy. I think batteries in the front will solve that.

Spring is near. I'm not sure if this will be the year for a test flight or not. I have over $1000 (approx 900 Euro) in it so far.

 

[DidierKlein 729]

Looking good keep up the good work, we really want to see it fly

 

[skint 61]

Yeah looking great! Cant wait to see the maiden flight

 

[schafe 3]

Good news! I have blown off most of my spring time chores and continued working on the plane.

I have tested the motors and 1 motor produces 250 watts of power. Next I need to weigh it and figure out if the math says it will fly.

[schafe 3]

Bad news. The "experts" on the internet formus say it is way too heavy. I guess I will rebuild the fuselage removing a lot of the plastic. Another year goes by . . .

[valcrow 144]

Looks really great!! don't get discouraged!