Hey, great video. I must really set myself up to make some videos...

The rigidity of the foam is dependent on the "unstretchability" of the CF strips. But don't forget that the hot glue is quite flexible, and will account for a fair bit of the bend we see in the video. A less flexible glue (ie CA or Epoxy) will stiffen the test piece up quite considerably. But then you end up sacrificing the CF strips, which isn't a great idea. My wings can take a weight of 10kg with about the same bend as I saw in your vid. But I epoxied my strips in.

On your actual wings, go with Epoxy or CA.

In full size planes we use what is called a "Shear web". Basically this is a thin sheet (ie single layer of glass cloth) running vetically through the wing tying the top and bottom spar caps together. What we do in model planes, is simply rely on the foam itself to tie the two spar strips together, and for the most part, that is all that is needed. In full size planes, this isn't good enough, and so we cut the wing from root to tip, insert a spar web, and bond the lot together. Now the two spar caps are held strongly in place, and simply can't move.

Just some background info I thought you might find interesting.

Duncan

Hi again,
I've just got back from the workshop, and there is yet ANOTHER job to do before I can do the job I WANT to do...

This time, it's extending the aileron servo wires so that they can reach the ESC. I don't have servo lead extensions. Bugger.

Anyway, in the meantime, I thought I'd hook up all the electrical bits and see if I could get them to work with the radio,

Fat chance. I had to solder all sorts of plugs onto the wires.

And so my first problem. I don't know what to connect to what. I've arranged the bits in what seems like a sensible order. From what you can see - is this correct?

Duncan

Originally Posted by jjoshj

Great video, Pat. I received my strips just yesterday also and have been wondering the same thing. I look forward to the one you do with them on the edge!

G'day Josh,

Didn't take much to insert the strips on their edge. Just a shallow cut with a hobby knife, keeping in mind that this foam is only very flimsy packing foam, and 10mm thick.

Surprisingly the strips on their edge are quite strong, but in my opinion not as strong as the same strips on their side. So that's the way I think I'll be going, and I'll use CA I think, as it's a bit of a weight saving over epoxy, although only a few grams.

Pat in Oz

Carbon fibre strips on edge (1 min 41 sec)

Originally Posted by rtfmaero

Hi,
Basically, we're comparing a beam height of 6mm with a beam of something like 40mm. No comparison.
Duncan

Thanks Duncan, I hadn't looked at it that way before, and it's just kinda sunk in a bit more.

With the strips I have being only 0.50mm thick, is it necessary to "rebate" the strips into the top & bottom of the wing ? And do the strips have to be exactly opposite each other, or can they be just "close". How much difference would it make if the strips are say, 20mm difference. I also have 4mm x 1mm strips although I haven't tried these yet.

Pat in Oz

Originally Posted by rtfmaero

Hey, great video. I must really set myself up to make some videos...

Duncan

Don't forget to hold the Mobius in your mouth. It makes for great sound effects !

Pat in Oz

Yes, the advantage of CF strips edge-wise is that is is SO easy to do.

I've done some calculations, and if you use 3mmx1mm strips, inserting them edge-wise loses almost nothing rigidity-wise over laying them flat on the surface. The difference in wing centre to strip neutral point is only 1.5mm. Negligible. Except that when you lay them flat, you have to somehow router out a 1mm deep recess. Which is very tricky. Cutting a slit and inserting the strip edge-wise in the CA-soaked slit produces a very clean finish, and MANY times the rigidity of the traditional tubular spar down the centre of the wing.

Go with the slit and the edge-wise CF strip.

Duncan

Originally Posted by rtfmaero

Hi again,
And so my first problem. I don't know what to connect to what. I've arranged the bits in what seems like a sensible order. From what you can see - is this correct?

Duncan

Looks good from what I can see Duncan. Just watch the polarity when you plug the servos in to the Rx.

Soldering is one thing I CAN do well, and a fine point soldering iron is a handy tool in the shed. I bought an Atten soldering station off EvilBay for about $25.00 and it has been just great for fine stuff. I do lot of 12V LED strip light installations which involves fine point soldering and this one is just great.

The bullet connectors and XT60 plugs are quite easy to set up.

Pat in Oz

Originally Posted by coongoola

With the strips I have being only 0.50mm thick, is it necessary to "rebate" the strips into the top & bottom of the wing ? And do the strips have to be exactly opposite each other, or can they be just "close". How much difference would it make if the strips are say, 20mm difference. I also have 4mm x 1mm strips although I haven't tried these yet.

Pat in Oz

You've hit on a very practical question. Yes, you will have to rebate the strips, which is a pain in the arse, and you won't get it right. Well, I couldn't get it right... So if you're using 3mm strips, slit them into the wing. I did. My protestations above were to do with the perceived additional strength slitted strips have over flat strips. This is a fallacy. But slitted strips (especially at 3mm) are MORE than adequate. And a whole lot easier/cleaner.

As for relative positioning...
Look, ideally, they need to be positioned exactly opposite one another. But (in the case of the Bixler) this isn't possible, due to the spar cutout strips. Any offset will cause a tortional force. As the wing bends upwards under positive G loads, any offset (top/bottom spars) will tend to cause some torsion in the wing, but we're not designing a full size plane here. The forces we're talking about are relatively benign. A 20mm offset is minimal. I'd ignore it. I have exactly the same issue in my Bixler.

Remember, your wing is orders of magnitude stiffer than the standard Bix anyway.

Duncan

Originally Posted by coongoola

Looks good from what I can see Duncan. Just watch the polarity when you plug the servos in to the Rx.Pat in Oz

Thanks mate. I must have a very poor soldering iron. Try as I might, I couldn't get the solder to fill the XT60 female recesses. I had to use the side of the soldering iron to do this. The tip seemed not to be hot at all. And then I couldn't get the already silvered wire end to fuse into the XT60 plug. Quite a f*ck up, to be honest. So I'll go grab me a decent soldering iron from Jaycar. And maybe a decent soldering power station so that I can see what temperature I'm working with.

You will notice, of course, that I am completely ignoring any possibility that my soldering skills are not up to par. Heaven forbid...

Duncan

Originally Posted by rtfmaero

Yes, the advantage of CF strips edge-wise is that is is SO easy to do.

Go with the slit and the edge-wise CF strip.

Duncan

Yep Understood.

The only thing I can see is that if you glue the strips flat, you can extend them up the curve of the wing a bit more, perhaps almost to the tip ? I don't know how much effect this would have that far to the tip of the wing though.

Pat in Oz

Originally Posted by rtfmaero

Thanks mate. I must have a very poor soldering iron. Try as I might, I couldn't get the solder to fill the XT60 female recesses. I had to use the side of the soldering iron to do this. The tip seemed not to be hot at all. And then I couldn't get the already silvered wire end to fuse into the XT60 plug. Quite a f*ck up, to be honest. So I'll go grab me a decent soldering iron from Jaycar. And maybe a decent soldering power station so that I can see what temperature I'm working with.

Duncan

I have a Jaycar iron as a spare and it's quite good, but not as good as the Atten station. Make sure you get one that uses "sheath" type tips that slide over the heating element, not the cheaper solid tips that you attach with a grub screw, they're crap.

Don't forget to put the heat shrink on ...

Pat in Oz

Originally Posted by coongoola

Yep Understood.

The only thing I can see is that if you glue the strips flat, you can extend them up the curve of the wing a bit more, perhaps almost to the tip ? I don't know how much effect this would have that far to the tip of the wing though.

Pat in Oz

Don't worry about the wing tips. The lift distribution of a wing is such that the wing tips see very little lift. The foam will be well able to handle that little lift on its own. I've extended my 3mm x .5mm slitted strips to just past the ailerons. That's plenty.

Duncan
PS And thanks for the tip re: soldering irons.
PPS Why to the Americans INSIST on saying "SODERING" instead or soLdering?

Part,
What sort of setup do you use for your videos? I would really like to produce a few videos, but don't know where to start. Your's are great. Short, to the point and instructional.

Duncan

Originally Posted by rtfmaero

Part,
What sort of setup do you use for your videos? I would really like to produce a few videos, but don't know where to start. Your's are great. Short, to the point and instructional.

Duncan

I use Wondershare - Video editor, and to save bandwidth I export the file as a Smartphone file, so where the original file on my mouth mounted Mobius is say 150 mb, the phone sized file is only about 25mb ( for example ), and all this takes only about 5 minutes from the time I download the .MOV file from the Mobius to the laptop.

I just upload it to Youtube and post the link to RC Groups. I created the "intro" from some free site that someone recommended. I just drag that intro video to the start of the main video using Wondershare, and you can insert transitions etc wherever you need. It's pretty easy after you mess about with it for a few hours.

Oh, I have no idea why they "SODDER" in the states instead of "SOUL-DER". It's always made me laugh.

Pat in Oz

I was just setting up my 9xr with some success, had it all working then I lost throttle input. Everything works except the throttle response now. Puzzled and confused as to what has happened and why it's stopped, any ideas?

*Edit* Somehow fixed but it reversed throttle and smashed a prop due to my lack of attention. Dammit. Think the 9xr needs to be put down until tomorrow!