PRANG Mini FPV flying wing

[Userofmuchtape&glue]

Hey all!

For a while I have wanted a small, tough FPV wing for flying through the scrub around my house and farm.
I researched the Turnigy Bonsai for a while, almost bought one then thought, hang on. $49 shipped for a 600mm foam wing? Yeah na... :black_eyed:

So then I wanted to design one based on the little Bonsai.
After a few scribbles on bits of paper and lots of dreaming I came up with the basic design,
and decided to call it the PRANG. Proximity Racing Acrobatic WiNG

MKI had a 600mm WS, ran on 3.7g servos, 600mah 3S, 1806 and a 30A ESC.
Needless to say is flew like a brick and was very weak! (230g)

MKII has a 700mm WS, 9g servos, 1000mah 3S, 2204 motor, 18A ESC and a carbon fiber spar.
It weighs 240g but has quite a bit more wing area and a better overall design so it flies great!

It is very powerful and smooth, and has not got a noticeable weak spot like the Arrow on ether side of the motor cutout.

So in the future I may sell kits but in the mean time please enjoy the PRANG!

You will have to scale up the plans to 700mm WS or if someone knows how to do that on TurboCAD then please let me know...

View attachment PRANG MKII.pdf



On the MKII prototype I did not cut holes for the servos as that weakens the wing in a already weak area, and it is not really needed on a small, light fun plane like this!

 

[PsyBorg]

Do you plan on glassing over the foam like a lot of the racers do to make the wing even stronger?

 

[Userofmuchtape&glue]

Not really, I rubbed PVA into the underside and light packing tape on the LE and belly.

The thinking behind this one is keep it light, so it can take a hit and fly slower for tree dodging. But if I have a larger version then I will ahve to look into it!

 

[Hai-Lee]

Abe,

It is very similar to the 800mm WS KFM4 wings I build. Unfortunately it seems that you still do not have a source of FB!

Mine do not have any CF and I actually remove a few layers of paper as well.

I seal all of the wing surfaces in Wipe on Polyester Varnish prior to painting, (it adds strength as well).

The glue which i use and have found superior for laminating foam is the SikaBond TechGrip from Bunnings.

As for the leading edge reinforcement I use the cloth reinforced tapes also available from Bunnings.

Mine run power from 100 Watt to around 300 Watt with the larger motors mounted forward of the engine bulkhead and the lighter motors hang off of the rear, (for CG reasons).

Currently I am looking at a rudimentary for of thrust vectoring for add loop response.

Have fun!

As for the re scaling of your plans just tell me the original dimensions and the dimensions you require and I could redo the plans for you!

 

[Userofmuchtape&glue]

I built a Red20RC 800mm Kmf4 wing, it was great but very flimsy with my HK foam!

I could buy FB from FT, but it would cost about $7.50 per 20x30" sheet at last estimation it is still a lot more expensive than my current foam!

So with your varnish do you coat the whole wing or just the open foam area's?

Is SikaBond like Gorillagrip? for the Prang I used a mix of hot glue and the craft glue you sent me, it seems to work well.

Most of the time I would use extreme packing tape, (fiber tape) but I ran out so I just used the lighter stuff.

I have not yet played with motor options but the Black widow 2204 motors with built in ESCs, firewalls and a UBEC weighs about 35g with up to 400g thrust.

Ha thrust vectoring would be fun! rad to make it light yet strong though...

So do you mean you would re do the plans from scratch?

Abe

 

[Hai-Lee]

The glue I used can be found here;- http://diy.sikaretail.com.au/products/adhesives/glues/sikabond-techgrip/

I use a paint scraper blade to spread it very thinly and then put the 2 pieces together and weight down until dry or set. It takes a while so there is plenty of time to readjust position before it sets.

Motors! I use the venerable 2205 up to the funfighter motor. The funfighter motor gives unlimited verticals!

The vectoring mechanism, (Prototype), will be done in light ply WITHOUT ANY BEARINGS and will add a little weight BUT will bring the motor a little closer to the CG so balance effect minimal. Servo mounted forward of or around CG as well. Mix done with elevator and Aux channel such that aux channel will function like a trim and elevator large input. Channel range limited for a very small negative and 100% positive output also. My version is just for pitch and not roll as the roll is always crisp but in loops they tend to be rather sluggish.

Describe your motor mount and perhaps I can draw up a vectoring motor mount to suit your requirements!

From scratch is always best when redoing plans If material sheet size is known then the plans can be drawn so that they fit on the sheet/s with minimal wastage!

Have fun!

 

[Userofmuchtape&glue]

Hi Hai-lee!

Is grave digging legal on my own thread? :black_eyed:

My sheet size is 700x500mm, and if you are still up for re drawing the plans I can send you the CAD file.

Abe

 

[Hai-Lee]

Abe,

Sadly I cannot use CAD files, (i am old school and still like pencil and paper), but if you can send me the dimensions or screenshots taken to scal I can do the drawings and return them in PDF format.

Have fun!

 

[Userofmuchtape&glue]

Sure thing, If I send you a screen shot will that help? the wingspan is 700mm.