• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

Dat Guardrail

#61
Glad I stumbled across this thread :)

I started a King Air model for 3D printing, but after printing and flying 5 other models (one I designed myself) that were fully 3D-printed, I've decided that one of the best uses of the technology is for additions to foam-based models (either foam-board or commercial). I've added a bunch of 3D-printed parts to my G-pig (and other models too). Some I designed myself, some were from Thingiverse. I just did the re-maiden with the removable nose that I designed to hold my RunCam. Worked perfectly, and got some great video.

Anyway, once you get this finalized, I may have to print some parts for it (nose tip, nacelles, etc.)
. gpig-gear.jpg gpig-nose.jpg KingAir3D.PNG
 
#63
I'm designing a thing with some similar design decisions. Could we get a look at the inside under the hatch?
And how are you doing a hatch tie-down?
Thanks @Namactual !
I certainly will, when I get the that point. There is not much to see at the moment. I don't usually put much thought into that kind of thing until I have flown one. Once I get an idea of where I am going to place the electronics and battery for CG I work those details out.

I usually use a craft stick, (pop sickle stick), for the tongue of a hatch. I will use either magnets, velcro or BBQ skewers to hold the back of the hatch down.

The main fuse hatch will use one of those methods. The nacelles will either be velcro front and back, or a semi permanent light gluing or cellophane tape. There is not a lot of room in those nacelles for anything else and they should only need to be removed if something breaks.

I do plan on 3D printing fancy latches that will work with the 3D printed motor mounts and such, but I try to make everything out of common materials so others can build them without the expensive tools.

And on that note:
Glad I stumbled across this thread :)

I started a King Air model for 3D printing, but after printing and flying 5 other models (one I designed myself) that were fully 3D-printed, I've decided that one of the best uses of the technology is for additions to foam-based models (either foam-board or commercial). I've added a bunch of 3D-printed parts to my G-pig (and other models too). Some I designed myself, some were from Thingiverse. I just did the re-maiden with the removable nose that I designed to hold my RunCam. Worked perfectly, and got some great video.

Anyway, once you get this finalized, I may have to print some parts for it (nose tip, nacelles, etc.)
. View attachment 167193 View attachment 167194 View attachment 167195
That would be sweet. Especially for the larger more detailed build.(y)
 
#64
Everything is pretty much done except the aileron control horns. The wire is too thin for the horns to bite into. I put a layer of Gorilla Glue on them and covered them with foam to give it some more meat, but it needs to dry before I put the horns on. I am hoping between the threads, glue and foam there will be something solid to attach the horns to. The elevator works great though.(y):rolleyes:
RC12U46.jpg RC12U47.jpg RC12U48.jpg
I dunno gents...
AUW with a 1550 3s battery is 550 grams. (425gr dry)
This thing has enough power to rip its wings off, but it is the wing loading I worry about.
I am going to give it a go if the ailerons work, but I do not see this flying very well.:cautious:

I think it is time to throw in the towel on this one. At the very least I have to shelve it for a while. Somehow this build has single handedly sucked the fun out of scratch building.

Either way, I am done for the night. Who knows, I might get back into it tomorrow.
 

jfaleo1

Junior Member
#65
Everything is pretty much done except the aileron control horns. The wire is too thin for the horns to bite into. I put a layer of Gorilla Glue on them and covered them with foam to give it some more meat, but it needs to dry before I put the horns on. I am hoping between the threads, glue and foam there will be something solid to attach the horns to. The elevator works great though.(y):rolleyes:
View attachment 167322 View attachment 167323 View attachment 167324
I dunno gents...
AUW with a 1550 3s battery is 550 grams. (425gr dry)
This thing has enough power to rip its wings off, but it is the wing loading I worry about.
I am going to give it a go if the ailerons work, but I do not see this flying very well.:cautious:

I think it is time to throw in the towel on this one. At the very least I have to shelve it for a while. Somehow this build has single handedly sucked the fun out of scratch building.

Either way, I am done for the night. Who knows, I might get back into it tomorrow.
I completely understand. I have two projects that have done the same thing to me. Some things just don’t work at a certain scale. You are right about wing loading. Sounds high. But you never know, the large amount of undercamber outboard may reduce the nastiest of the top stall.
 
#66
I completely understand. I have two projects that have done the same thing to me. Some things just don’t work at a certain scale. You are right about wing loading. Sounds high. But you never know, the large amount of undercamber outboard may reduce the nastiest of the top stall.
I don't want to give up on the design, but I think I am going to focus on the larger build. I am just trying to pack 10lbs of :poop: in a 5lbs bag at this scale. I have the control horns gluing now and if they hold I probably will give it a toss and see what happens. I am not expecting much though.

In either case, it will be a while before I fly. I think I may have fractured my thumb. I can't say if it is broken for sure, but my palm\thumb area is the size of my wrist. Of course the doctors office is closed to visits and I have to wait for a phone consultation later today. I am sure they are just going to order an x-ray.

Good news is I can still use a mouse, sort of, so I guess it's on to the larger model redesign.
 

Tench745

Elite member
#68
This plane looks so good, it would be a shame to let the design founder.

What's your wing area? You said this is 1/20 scale? Using that I come up with a wing area of about 109 inches, putting the wing loading at 25.4 oz/sqin and a cubic loading of 29.1. That's pretty darn heavy. If you could drop about 10oz from the weight that puts you in a reasonable cubic wing loading for a scale subject.

Alternately, if you doubled the size to 1/10th scale but kept everything else the same you would quadruple both the wing area, and the aircraft's empty weight. Electronics and batteries would add only a fraction onto that.

I guesstimate the empty fuselage is about 250grams? Meaning electronics and battery added about 300g?

So if you doubled the size you'd have a plane that weighed about 1300g (45.8oz) with a wing area of about 436 sqin. You'd have a wing loading of 15.2oz/sqin and a cubic wing loading of about 8.7. Even if the all-up weight quadrupled, you'd be sitting at a cubic loading of around 15. That's a bit high, but still flyable.
 
#69
The wing area is about 125, I gave it a bit more cord over scale. The wing loading is still way too high though. I might be able to shed an ounce or two, but there is no way I could reduce it by 50%. On top of that, one of the main reasons for this build was to make the painted skins for it which is only going to add more weight.

This design will be built, but I just don't see it happening at 1/20. 1/12 - 1/10 would be quite do-able. And easier to put the electronics in.
 
#70
The wing area is about 125, I gave it a bit more cord over scale. The wing loading is still way too high though. I might be able to shed an ounce or two, but there is no way I could reduce it by 50%. On top of that, one of the main reasons for this build was to make the painted skins for it which is only going to add more weight.

This design will be built, but I just don't see it happening at 1/20. 1/12 - 1/10 would be quite do-able. And easier to put the electronics in.
What's the wing cube loading at right now?
 

b-29er

Well-known member
#72
if you're worried on the weight, i'd almost drop the battery down to a 2s700 or something like that, maybe even drop the motors down to something spinning a 3" prop like those micro quads use. Those motors would give you in excess of a 5:1 thrust to ratio with the prerequisite 4s lipos, and even on 2s i'd suspect you're over 1:1, and if not, could probably benefit from a 6" prop due to low rpms with the same motor.

edit- on looking up some thrust test videos, looks like on 3s you can still get over 1kg on a 6" prop. i'd suspect you'd never need to touch full throttle on 2s.
 
#74
if you're worried on the weight, i'd almost drop the battery down to a 2s700 or something like that, maybe even drop the motors down to something spinning a 3" prop like those micro quads use. Those motors would give you in excess of a 5:1 thrust to ratio with the prerequisite 4s lipos, and even on 2s i'd suspect you're over 1:1, and if not, could probably benefit from a 6" prop due to low rpms with the same motor.

edit- on looking up some thrust test videos, looks like on 3s you can still get over 1kg on a 6" prop. i'd suspect you'd never need to touch full throttle on 2s.
Aye, thrust wont be an issue for sure.
The real fix for the mini build is simplifying a lot of the geometry and using far smaller electronics. Even without a battery it is still way too heavy. Unfortunately I don't have the electronics required and even if i did, I would not be able to skin the final product like I wanted to anyway.

I did some math and decided 1/10 is too big. That is a 6' wingspan with the wing tanks. I am going to go with 1/12 scale. This is still quite large, about the same size as the master series P-38. I think that is about the best option with a twin "C" pack.

I will come back to this, but I am going to switch gears for a bit. I have another build I need to work on.
 
#75
Just a little update.
The control horns did in fact glue to the rods with the foam filler quite nicely. Plenty strong enough.

After some time to think and come to my senses, I don't think I am going to attempt to fly this though. I am sure it will fly, above 60mph. There is too much potential for damage. Pancaking or puncturing batteries, stripping servos, etc. It's just not worth it.
 

Daniel Liutan

Well-known member
#76
Just a little update.
The control horns did in fact glue to the rods with the foam filler quite nicely. Plenty strong enough.

After some time to think and come to my senses, I don't think I am going to attempt to fly this though. I am sure it will fly, above 60mph. There is too much potential for damage. Pancaking or puncturing batteries, stripping servos, etc. It's just not worth it.
Hi Namactual,

Could you post the plan, please ?
I think it going to be a great plane and i really want to build one.

Thanks.
 

Namactual

Elite member
#77
I will, although I can't say when. It needs a lot of work.
I just had to step away from this project for a few. It was starting to frustrate me. I will get back to this very soon.
I am almost done with my test Raptor. As soon as that is finished I plan to finish this design, release the plans then skin it.
 

Daniel Liutan

Well-known member
#78
I will, although I can't say when. It needs a lot of work.
I just had to step away from this project for a few. It was starting to frustrate me. I will get back to this very soon.
I am almost done with my test Raptor. As soon as that is finished I plan to finish this design, release the plans then skin it.
Two weeks. Just come and have a look :cool: Any update?
 
#79
Nothing yet, sorry about that.

I am going to be out of commission for a while. I had to get tested for covid today and if that comes back negative I have surgery on Friday.

It's nothing life threatening, just very uncomfortable.
 

SquirrelTail

Legendary member
#80
Nothing yet, sorry about that.

I am going to be out of commission for a while. I had to get tested for covid today and if that comes back negative I have surgery on Friday.

It's nothing life threatening, just very uncomfortable.
I hope that you're all right! If you have COVID, I'll pray for you to have a fast recovery!