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Aug 25, 2016, 05:21 PM
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Thread OP
Help!

3D Printed RC Plane Wing Covering Help


Hello All,

I am currently in the process of building a scratch built RC plane, which is made out of 3D printed parts. Right now I am in the process of covering the wing with heat shrink film. As I have never covered an aircraft wing before, I am not sure if I did it well enough. I have attached pictures of the wing, and I was hoping that someone could explain if I did it well enough, so that it can still fly. I have watched tutorials online and this is my second attempt, but I still do not know if it is good enough. I would really appreciate the help

If anyone has any questions or is interested in my project, I would be glad to answer them. I should also mention that this is the first time I have tried to scratch build a plane, so any tips would also be appreciated

Thanks!
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Aug 25, 2016, 05:32 PM
Pro Hoarder
turbonut's Avatar
You need to add a leading edge and a trailing edge to your wing for the covering to attach to. As is you are not able to shrink it properly
Latest blog entry: In flight
Aug 25, 2016, 05:40 PM
Registered User
Thread OP
Thank you for the advice. I do not think I will be able to add a leading or trailing edge to the wing at this point. As is, do you think that the wing will not be able to function with the current covering?
Aug 25, 2016, 09:45 PM
Letís eschew obfuscation.
scott swanson's Avatar
Learning to cover takes a bit of practice--don't get discouraged if your first attempt doesn't come out too well. For example, you have already learned that you need a leading and trailing edge to get it to cover correctly.

Have you shrunk the covering yet? The wrinkles don't look so good, but probably won't affect flight that much at model speeds. The gaps in front of the ailerons are a bigger concern.

Tell us a bit about your model. What is the weight, wingspan, and motor? And what is your skill level as a pilot?

My biggest concern is that a primarily plastic model will be heavy. This wouldn't keep it from flying if it has enough power, but if heavy it won't fly at speeds slow enough for a newer pilot to keep up with.

I personally think designing and building my own models is one of the best parts of the hobby, and my hat is off to you for building this example. If it flies well, great. If it doesn't, look at all you have learned while building it.

Scott
Aug 26, 2016, 05:32 AM
Registered User
Thread OP
Thank you for your reply and kind words

I think I have shrunk the covering, but I will try and shrink it some more. So I should add a bit more covering next to the ailerons if I understand you correctly?

The Model has a weight of about 1.2-1.4 Kg, depending on how much extra ballast I add to the nose. When designing, the model, I did not take into consideration the significant eight of the tail surfaces, when empty the C.O.M is actually pretty close to the tail Servo!

The wingspan is 1300mm, not including the center part of the wing. The airfoil used is S1223, which has a max lift coefficient of around 2. Due to the low Reynolds number which the aircraft flies at, this might be lower, I will probably add vortex generators to the wing to help combat this

I calculated the stall speed to be around 15mph/24kmh

It is powered by a park 480 with a 11x4.7 prop, which says should produce 1.1kg of thrust

I have flown other R/C aircraft before, but they were all foamies, trainers or warbirds. However I am not confident in my skill level as a pilot, and I would probably trust someone else to fly it more rather than myself. I should also mention that this is for a school project, so I am keen for it not to crash instantly (although this may happen anyway ), and if someone else wants to fly it first instead of me I would gladly welcome them

In terms of completion, the model is almost finished. All the control surfaces work and I have tried a full power motor test and the fuselage held up fine, thankfully the motor did not just fly off of its mount. I will fly it next weekend most likely

I have two questions. When the control surfaces are in place, should I hot glue the linkages to the control horns, or is this not necessary. I am attaching the wing to the fuselage by rubber bands, do you think the best place to attach rubber band mounting points to the fuselage is the bottom, behind or front, or some other place

Thank you again for your Response
Aug 26, 2016, 07:31 AM
Neophyte hacker
portablevcb's Avatar
First, congratulations on such a project. Looks good so far.

Second, look up some other builds and see how wings are constructed, including rubber band wing attachment and control linkages.

Take off that covering. You can add LE and TE pieces. Just make some parts that will slide between the ribs and glue in place. Same for the section just in front of the aileron.

Then you can cover as normal. Look at some other build threads in here to see how. Or look here:
https://www.rcgroups.com/forums/showthread.php?t=711624

CG. That is going to be your real issue. If it is far back now you may need to add a LOT of weight to the nose.

The linkages need to pivot freely. Use wire and bend the ends to fit into the horns. You can use any number of commercial items to fix them. Look up Dubro products.

Rubber bands need something to attach to. Most planes that use them have two dowels through the fuselage at the front and back of the wing. The rubber bands are looped around one, then around the bottom of the wing then looped over the other dowel.

charlie
Aug 26, 2016, 11:45 AM
Registered User
Thread OP
Thank you for the response,

After trying to shrink down the covering more, I got better results, they are still not great, but they are better. While shrinking them, it is clear that adding a leading and trailing edge definitely would make the covering a lot better. However, the project needs to be completed soon, so I will not have time to add a trailing or leading edge, I will keep it in mind for next time

As for the rubber bands, I am a little bit confused, if I put the rubber band under the wing, how will that secure it in place, or am I supposed to put the wing in the loop?

One more thing, one of the ailerons can travel a lot more up and down than the other one can, is this an issue or does it not matter?

Thanks again for the advice
Last edited by 3DPrintedRCPlane; Aug 26, 2016 at 11:55 AM.
Aug 27, 2016, 08:18 PM
Neophyte hacker
portablevcb's Avatar
Sorry, I assumed this is a low wing plane so the comment about putting the rubber bands under the wing. If it is a high wing plane they go over the top.

Covering is not really suitable for flying yet. You still need to fill the space in front of the ailerons.

By one aileron moving more than the other do you mean when you move the stick the servos don't move the ailerons the same amount? Are the servo and aileron control horns the same on both sides?

If you just mean that one aileron can move on it's hinges further than the other, that's not an issue. Typically you only need about 30deg up and down for ailerons and can sometimes do with much less.

charlie
Aug 30, 2016, 09:18 PM
The Other Side of Your Screen
SilverSport's Avatar
I am not intending to sound mean.

I was away from the hobby for 25 years and have not covered a plane since returning 2 years ago, but did build a half dozen from kit and scratch flying box type airplanes back in the day. First thing I see missing from all your pictures is your tools, what you may be attempting to cover with may not do the job if all else was right.

I can tell you have a deadline of some sort, I just hope that deadline does not require a test flight, that will not happen with what you have there, the servos are not mounted properly, aileron flutter will abound and send you down unless you ROG ... which your will probably not achieve flight from.

I think you may need to start with building an old fashion balsa kit for at least a 15 - 25 glow motor size aircraft. I would suggest a Sig model as they are known to have good build instructions. This should help you learn how to design all aspects into your project which will as mentioned include a leading and trailing edge, possibly some sheeting along the upper leading edge and both upper and lower trailing edges for both strength and a place to attach covering material. How to build a strong mount for your servos. How to attach ailerons - and many more lessons which I am sure would help you tremendously with the rest of the airframe that we have not seen.

You can quote the specs of a given airfoil design, but if it will not keep that shape you don't have an airfoil with those specs, you have a pile of parts that will either not get off the ground or will kiss the ground in the worst kind of way.

Also, take a look at this design https://3dprint.com/86986/3d-printed-spitfire-mark-xvi/ - this may require much more programming into the 3D printer but they have solved your covering problem - they printed everything not electronic.
Sep 05, 2016, 04:17 PM
Registered User
Thread OP
Sorry I haven't been able to respond yet guys, I have been busy getting back to school and completing homework so I haven't had the time to respond, I posted an update to my project here. Thanks again to everyone for helping

https://www.rcgroups.com/forums/show...6#post35654232


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