SkyTouch, was initialy a prof of concept project for a future, bigger FPV flying wing. It was designed for stability.
- Wingspan 1200mm
- Wing area 34.2 dm2
- Weight 750g ( without FPV )
- Power plant 2830 brushlles motor with 33A ESC and 10x6 prop
Construction:
Foam core wing sheeted with balsa then covered with SolarFilm. Initial design was to have the wing splitted in three, the center section and two wing panels but a mistake during build convinced me best is to have one piece wing. The center section I've covered it also with fiberglass and epoxy rasine to make it stiffer for landings. The winglets are from 3mm balsa with 1mm fiberglass strips on both sides.This do not allow the wood to bend in time. Winglets are removable so the wing enters my car truck and I am verry happy abot that.
All the electronics was to be inside the wing body so there will be no fuselage.I could use a thicker airfoil at the wing root if necessary, but for now I've choose MH60 airfoil because I have had good previews experience with it.The servo's are also installed on the center section and the rods are made with bouden lines.
I can tell, I have googled a lot for an idea but then I've realised that this should be my own design so why not turn my back to google and use only design goals and tools to make it.
So I've set the goals for the model:
Initial design goals:
g1. Max Payload 250g FPV equipment ( 30 to 35 percent of the total weight)
g2. Target wing loading 25 g/dm2
g3. Stable flight for FPV
g1 says 250g is 30% of the toatal weight so we should have more then 830g total weight for the wing. Let say 850g .
g2 say 25g/dm2 at max payload results 25 dm2 of wing area.
In order to have the g3 ensured on a flying wing we need the thing to be a bit speedy which sends me to think best solution is a backwards swept wing and lower aspect ration.
From previous experience 50deg sweep is to much ( "Chancy" was to low AR) but 32deggrees is close to it ( SkyTouche is fast and stable ). Let's choose 30degree sweep angle.
With all this data is time for me to figure out the size and shape.
My previews build was aspect ration 4. I would say a bit small for what we need here. Let's target AR=4 so with wing area of 34dm2 (AR = b2/S) the wing span is 1.16m. So let's choose 1.2m.
Initial design goals:
g1. Max Payload 250g FPV equipment ( 30 to 35 percent of the total weight)
g2. Target wing loading 25 g/dm2
g3. Stable flight for FPV
g1 says 250g is 30% of the toatal weight so we should have more then 830g total weight for the wing. Let say 850g .
g2 say 25g/dm2 at max payload results 25 dm2 of wing area.
In order to have the g3 ensured on a flying wing we need the thing to be a bit speedy which sends me to think best solution is a backwards swept wing and lower aspect ration.
From previous experience 50deg sweep is to much ( "Chancy" was to low AR) but 32deggrees is close to it ( SkyTouche is fast and stable ). Let's choose 30degree sweep angle.
With all this data is time for me to figure out the size and shape.
My previews build was aspect ration 4. I would say a bit small for what we need here. Let's target AR=4 so with wing area of 34dm2 (AR = b2/S) the wing span is 1.16m. So let's choose 1.2m.
First Flight:
The first flight went very well. I have forgot the cover home so I've cut one from a book cover. Actually the ideea for the plane name came from the kid that is touching a light in that picture.
I have adjust the controls throw then I've added +4 trim on elevator to have some safe up control. As I was on the field only with few young kids, I had to launch the plane myself. I've tucked the wing from the right LE and throw it about 30 degrees up, then I've moved my hand on the control. It was successful and the wing flied really well. I am very happy with the results.
Flying:
It is a nice looking wing and flies even better. Is a fast runner and so wind does not influence it. I was afraid the aerobatic capabilities will suffer as it is a flying wing but the only maneuvers that are not possible are the ones that are done using rudder on a standard tail plane configuration.
Also it has good gliding capabilities.If I want to fly for long time you only need to add 25-30% trust.
Landing:
First landings were tricky as because of the gliding performance and because there are no air-breaks you need to lineup with the landing way earlier and lower.But then you just need to stop the engine and to let it lay down. I've fly about 12 short flies and all landings were excelent.
