Originally Posted by steveobhave

Hey Gazz, it's pretty heafty actually. I think it's something like 8oz bi-directional cloth laid out at 45 degrees and I've used two layers (but there is a fair amount of overlap with two 1.5 inch strips of unidirectional glass wrapped around the fuse at 2 points for 'hoop' strength. It's come out really solid. In terms of the motor mount, it's at a 90 degree angle at this stage but that might change depending on what the flight characteristics are like. I was really hoping to get the maiden in this weekend just gone but I ran out of time. The electronics bays ended up taking a really large amount of time.

Thanks for the comment Gazz, it's great to have someone actually pipe up every now and then I thought there might've been a little more interest but there you go.

a lot of people will be watching this thread mate even tho not many replies

Just a couple of extra little bits done. It got too warm to keep working so I had to stop, I'll likely do a bit more this evening. I need to route the servo wires and install the servos then cut the slots for the control horns.

Second elevon cut


She's looking a bit more business like now!


Control Horns

hey steve coming along nicely have u tested the CofG yet to see if it will balance?

Yeah, from tests it looks like all I will need is 60g of ballast in the nose to get it properly settled with two 3000mAh batts in there and my Contour camera on the nose. It'll be about 180g without. Not bad for an almost 3kg plane!

Servo holes cut and hollowed out. I still haven't decided how I'm going to seat them, I'm thinking that a light ply insert or some sheet fiberglass might do the trick.


I've tunnelled out foam from the servo recesses and also through to the electronics bay. I've also made recesses for the servo connectors and the wires so that if I need to change them it's just a matter of lifting the elevons and swapping them out.


Both servos and control horns installed but not permanent yet. I will use a standard two part epoxy on the control horns but I need to be able to replace servos if they die.




Kahu will be pretty clean when she's all done and I'm still trying to decide if I want to put a duct forcing air both into the electronics bay and also to the motor or if I leave the motor in the wind. Again it's a case of making sure that I'm able to easily replace parts if they fail. I still need to figure out how to make the motor mount removable. The final thing that I will need to decide on is if the trailing edge in front of the prop needs to be streamlined - I'm guessing that if I want her quiet that a nice trailing edge will be needed.


This will be it till I can get back to the hangars because I need to clean up the elevon interfaces, probably with some micro, before I install the hinges and then it'll be test flight time!

Final(ish) CG calcs done using http://wingcgcalc.bruder.com.br/en_US/?

I gave myself a bit of a fright by not measuring properly the first time and the CG came out a good 25mm or just shy of an inch forward of what I though it was but then after some rather concerned and extremely anal remeasuring it came out exactly where I was expecting it.



First test throws followed by the first test flight will be this weekend. I am quietly pooping myself as it's a whole lot of plane and she's no foamy...

"I really need to finish one of these planes... I've told myself that I'm not allowed to start any more until I finish one first!!!"

Ha! That is my problem too. I'll be working in my shop on something, go looking for a part, tool, whatever, find something I forgot I had, and think, "Gee, I could make this into a really great (whatever) - I have the attention span of a qnat, which is definitely less than a goldfish, lol.

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Man, this build is awesome, can't wait to see her flying!

looking good!

Any news?
Stuart

Great thread...excellent work...

I should be getting some work and hopefully first flight this weekend. Last time I tried to get it launched it ended up being a bit too cumbersome to hand launch so I've rigged a bungee but I'm going to have to put both a rail and a hook on the bottom of the wing to make launching a bit less painful. She's going to be a bit quicker on the landing than I was expecting I think.

Looks great Steve!

Could I suggest you just glue your servos in with hot melt glue. If you glue around the outer perimeter of your servos you will be surprised how firmly they will be held in the foam.

Also, could I suggest you shorten your servo arms way down - even so they are below the wing surface - as you will find your elevons won't need much travel and it is best to make use of the mechanical advantage that will bring - rather than dialling down of throws on your Tx to probably less than 20% that the current servo arms will require.

Don't worry about the landing, it will be easy so long as your CG and throws are OK!

Having the towhook will make it pull up really quickly when it does touchdown.

Just on your CG calculation, it looks like you included the area of your winglets in the calculation. Is that right? I just think your proposed CG location looks to rearward by about 30mm.

Good idea about using a bungee too!

Regards
Peter

Originally Posted by Peter M

Looks great Steve!

Could I suggest you just glue your servos in with hot melt glue. If you glue around the outer perimeter of your servos you will be surprised how firmly they will be held in the foam.

Thanks! Yep the servos are hot melted in for sure.

Originally Posted by Peter M

Also, could I suggest you shorten your servo arms way down - even so they are below the wing surface - as you will find your elevons won't need much travel and it is best to make use of the mechanical advantage that will bring - rather than dialling down of throws on your Tx to probably less than 20% that the current servo arms will require.

I think that the servos that I have will need to be replaced anyway. They don't seem to be overly accurate and don't centre as nicely as I'd like. It's a little frustrating but there you go. I see what you're saying about the servo arms and it makes sense as the elevons have a stupid amount of travel at the moment.

Originally Posted by Peter M

Don't worry about the landing, it will be easy so long as your CG and throws are OK!

Having the towhook will make it pull up really quickly when it does touchdown.

Just on your CG calculation, it looks like you included the area of your winglets in the calculation. Is that right? I just think your proposed CG location looks to rearward by about 30mm.

Good idea about using a bungee too!

Regards
Peter

In terms of calculating the winglets into the wing area, this is correct as the winglets are not just wingtip fences. They are actually flying surfaces with an identical airfoil to the main wing. As a correct aerodynamic calculation a flying winglet has the same effect as a wingtip extension of the same length with the added advantage of allowing the wing to generate more lift because of tip vortex reduction.

The wing has a fairly benign glide from the throws that I have completed so far but I can't get it floating for long enough to get the 11 inch prop spun up. Doing some cursory hang tests (giving it full throttle whilst hanging the wing from my hand) it has plenty of power once the motor spins up, it's just getting enough forward speed to get it flying.