|Apr 18, 2014, 01:23 AM|
Frenzy MkII flyingwing
This thread was meant to be a blog but I have since decided to move it to this forum.
This will be my first build log. I'm keen to try and express my own style
geared to being more media rich and entertaining.
Here is a link to the original Frenzy Its not a build log just some of the guys on the modeling
science thread helping me work out some of the bugs. The construction techniques will be
the same as in the original and it will be dimensionally similar.
Panel span: 783mm
Root chord: 292.65mm(MH-60)
Tip chord: 100mm(NACA0008)
Wing Area: 30.74dmē
MAC Length: 212.08mm
Wing Load: 39.04g/dmē
Construction: Foam core sheeted balsa.
Dualsky XM2834EA-9 Brushless motor
Dualsky XC2512BA 25 amp brushless ESC
Turnigy nano-tech 2650mah 3S or
ZIPPY Flightmax 2650mAh 3S
Master Airscrew 10x6 S-2 (Scimitar) Series
Radio Control Gear
FrSky D8R-II PLUS 2.4Ghz 8CH Receiver
Hitec HS-82MG Micro Metal Gear Servo
Hobbyking KK2.0 Flight Control Board
Designing of the fuselage in Solidworks 2013
Cutting the fuselage
|Apr 18, 2014, 07:06 AM|
An important design parameter is the twist that you build into the wing.
How much twist depends on it's intended use. More twist for a thermal floater and less for a speed demon.
Curtis Suter has an Excel flying wing spreadsheet on his website that can get a design into the right ball park.
|Apr 18, 2014, 07:41 AM|
I noticed on your last build you have the male bullets attached to your battery. You might want to consider moving those to the esc and use the female bullets on the battery, less chance of shorting.
|Apr 18, 2014, 01:32 PM|
That looks REALLY SEXY!
One thing though. Drop the full span elevons. The inner half is located inwards too far to work well for either the aileron or elevator functions. All you will get from the inner portion is drag with precious little other effect.
Instead use only the outer half and run flexible pushrods through slots cut into the wing core that extend out and curve smoothly over as wide a radius as possible to meet the elevon horns. Or run the servo wires out and mount the servos out at the mid point of the wing.
I assume that the motor is going on the flat spot at the rear of the center pod?
|Apr 18, 2014, 10:19 PM|
|Apr 19, 2014, 02:58 AM|
United States, CA, Fremont
Joined Jan 2009
Wing twist, meaning less angle of attack at the tips, prevents tip stalling. It causes the wing to stall closer to the root and that just results in loss of lift and the wing just drops but remains horizontal. A tip stall can cause a death spiral.
I usually twist my wings after they're built by placing them in the hot sun while the tips are twisted using weights.
|Apr 19, 2014, 03:25 AM|
A link to the file Herks mentioned.
I presume you'll be making the wings detatchable?Two centre sections,one unpowered for sloping would be cool.
|Apr 19, 2014, 06:16 AM|
I had originally thought about twisting the wing but after thinking about it I have decided not to.
The MkI had no tendency to tip-stall and spin even when flying in a tail heavy condition.
|Apr 21, 2014, 02:31 AM|
Cut the fuse today it went really well and was pretty quick just a couple of hours in it.
I was looking at the wing design on Friday and I can see an issue with it.
The tip cord is very small in length and thickness and it has very little surface area Iv done away with sheeting the wing in balsa and instead I'm covering it with paper and pva. So know I have reduced strength at the tip compered to balsa sheet.
The problem is how am I going to attach the wiglets to the tips of the wings? Iv been thinking about it all day and come up with nothing.
|Apr 21, 2014, 02:53 AM|
These are carbon tubes in the wing,rods in the winglets.If you incorporate say 25 mm of the wing into the winglets(sort of a L shape)you will be able to tape them on,or use a screw fixing.
What sort of spar system have you planned?
|Apr 21, 2014, 04:04 AM|
You could also probably glue and then laminate them in with the rest of the wing, if they're permanent.
I've had some success attaching stuff with a hot glue anchor, which I tend to favour if it looks like carbon rods will be too rigid, and tear surrounding material in an impact :
- In both sides, drill a hole to a suitable depth (up to a couple of inches, as long as you'll be able to fill it with hot glue without leaving air pockets), or cut a suitably shaped recess.
- Pump plenty of hot glue into both sides until it fills the hole to excess. The glue should have plenty of mass, and retains its heat long enough to be workable for some time, allowing you to place several of these anchors in each surface.
- Press surfaces together, ensuring that the molten glue from each side mingles and forms a strong single piece.
The result is a strong, impact-resistant anchored joint, in many ways equivalent to, but often stronger than, a nylon bolt.
For attaching thin surfaces, drill right through, and scrape off excess glue from the outside after pressing together, to leave a flush surface.
|Apr 22, 2014, 02:12 AM|
I cut the wing pylons, it was ez enough. Cutting the wings, not so ez. I cut five out today and only one of them is useable
I blew up my good hotwire foam cutter some time ago and never got round to fixing it. I borrowed my dads and it is really
good for cutting on a small wire but not so good for longer wire also I dont have any nichrome wire so that dosnt help aswell.
I have ordered some so ill have another go when it arrives.
A bad day for cutting wings.
This is what I have to work with for attaching the wiglets
All the cutting is done
I haven't had to use spars in the past for a balsa sheeted wing. But im not to sure about a paper sheeted wing.
Ill use one of the reject wings to do some tests
Balsa sheeted wing loaded with 13.8Kg of weight.
|Apr 22, 2014, 04:42 AM|
I thought this was a neat way to do winglets on a foam wing.Also check out the amount of stiffening used-and this is a glassed wing.
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