RC Plane

#1

Good afternoon all!

I have been given 2 very old RC planes that were found in a loft and were destined to a skip!

After a bit of a play with it I am in this situation:

  • Both nitro glow engines are completely seized, 1 week in WD40 has not helped, I am open to suggestions.

  • All the electronic and the servos are 100% working, I have bought a new transmitter (FlySky i6x) and successfully tested all the components. Very happy with that.

  • The tail surfaces are a little damaged and worn, but they are made of balsa wood, and I am confident I can repair them.

Now the bad news… both wings are beyond repair, and I will need to make some new ones

@scday94 Suggested 3D printing the new wing and I really like the idea.
Some new filament from bamboo seems to be the answer thank you to its very low mass, but I am not completely convinced (ASA AREO filament here https://uk.store.bambulab.com/products/asa-aero )

The specs below are a comparison of ASA Aero and ABS

ABS%20VS%20ASA
ABS VS ASA.png1479×825 193 KB

I can see that the abs is stronger in pretty much all the mechanical properties tested with a very small difference on weight (1.05 g/cm³ of ABS Vs 0.99 g/cm³ of ASA).

My doubts are in relation of :

  • Price - ASA is quite more expensive than standard ABS

  • Printability - ASA is a new material, and looking online, it looks like it is a bit temperamental and difficult to set up in the printer, while ABS is well known and tested, which could minimise the failures and improve the finish.

  • Compatibility - I have no idea what glue or paint to use with ASA, while again ABS bonding is quite well documented

To conclude I was thinking to print the first wing in ABS and try to do a maiden flight. The extra weight does not concern me too much, as the glow engine that came with the model seems more than powerful enough to generate the necessary trust.

What are your thoughts?

Below is a screen grab of the work in progress 3d design of the wing (1200mm x 295mm)

wing%203d
wing 3d.png1679×874 286 KB

#2

@Oddstag - I know you have been printing a fair bit with ASA though not the aero stuff. Have you done any post processed parts? is there much of a preference on ASA vs ABS other that the fumes?

The filament guide below shows a bit better all round strength/stiffness/toughness as well as a slightly better heat resistance but not as good interlayer bonding. this is normal ASA not the aero stuff. The cavitation introduced by the foaming seems to drop the strength a fair bit based on the data sheet you shared.

Shame the Aero filament is not noted in this chart at the moment.

https://bambulab.com/en/filament/guide

#3

I’ve printed quite a bit with ASA. I chose it over ABS because it claims to warp less than ABS, I still had corners lift from the print bed on some parts during printing. Dialling in the settings on either material to limit warping will be a problem you need to overcome on a part that big.

The other big problem to think about is the orientation you plan on printing that part. None of the printers will print something that size in one go. If you split it and print horizontally you’ll want a flat base or you’ll use a lot of supports. If you print it vertically you’ll sacrifice strength as the layers would be perpendicular to the force and you’d probably want a spar or something through the wing.

If you’ve not done a lot of 3d printing lightweight PLA might be a better starting point (e.g. https://uk.store.bambulab.com/products/pla-aero). It’s definitely not as strong as ASA but should be more forgiving to start with. I’ve seen plenty of people on youtube printing planes with LW PLA

#4

Thank you for your insights,
The matter of the strength of the print did occur to me, and in the model I have allowed the space for x2 carbon fibre tubes to be inserted from one end to the other.

My experience on 3d printing is basically not existing, so I am looking for the least fiddly solution :slight_smile:

#5

I have no experience with lightweight or aero ‘grade’ filaments so can’t speak to their particularities. My first thought is that any form of ASA over the other offerings is going to have superior weatherproofing and uv resistance. Simply put, ASA is suitable for an object intended for long term use outdoors and the others not so much. They are more prone to deterioration when exposed to water and more importantly UV radiation.

If that is not a concern for you, I would be tempted to suggest PLA as it is surprisingly strong and much easier to print, as you know. While it’s worthy to compare various materials for their various strength characteristics I think it’s important to remember that these represent in some ways ideals, and generally speaking one is more likely to get PLA to print in its ‘ideal’ state than ASA, which even if printed successfully may suffer from layer adhesion issues that are invisible to the eye but all too apparent when something snaps 50 metres above the ground.

If ASA is required then in the Bambu glue on the buildplate is an absolute must to have any chance. With any printer preheating the chamber before printing is equally important. The chamber has to be sealed not only because of the fumes, but also because the slightest draft can cause warp.

For post processing the methods are identical to ABS. Parts can be vapour smoothed and chemically joined with acetone.