Speed Freeks - Dynamic Soaring & Electric 3D enthusiasts

This project has been a long time coming, but is finally starting to gain some momentum. The design parameters were very simple.....a small DS machine that is literally unbreakable in the air, and has the durability to cope with some of our 'less than hospitable' landing zones.

The picture above shows the fuse as it is now. It was constructed by wetting out Carbon/Kevlar Braided Sock (which was apparently a reject from the airforce and Ive since been told you just cant buy it in Oz) over a blue foam plug and then added 3 layers of 3oz crows feet weave fibreglass over the top. I used mineral turps to eat the foam out to leave a hollow fuse. So far it looks pretty good, but I still have to do one more light sand and clear coat before cutting out the hatch. The walls of the fuse are about 1.5mm thick, and it currently weighs 250 grams. I expect it to weigh around 280 grams after reinforcing the fuse with some more kevlar around the wing saddle and nose.

The wings have been cut and split to accomodate carbon graphite golf club shafts for strength, and will be joined to form a 1 piece wing. Ply, reinforced with kevlar, will be added to the wing join area where the wing bolts will be secured. The V-Tail will be shaped balsa which is vac bagged with fibreglass and will be secured using 2 bolts, making it removable.

You can see how the wing cores have had grooves cut out to incorporate the spar, which was done by hotwire and templates. The spar will be glued in using epoxy and micro-balloons to fill the gaps in preparation for vac bagging. Im still deciding on what layup to use for the wings, but Im temped to just go all out and go for 2 layers of 199 GSM carbon at 45 degree bias and a fibreglass veil over the top to prevent pinholes in the paint transfer off the milars. The wing should be incredibly strong as you cant physically break the spars on their own, and together with the carbon skin, should make for quite an over-engineered wing, which hopefully will prevent structural failure in the most extreme DSing conditions. Mind you, the ultimate strength in the wing is completely dependent upon the strength of the join between the 2 wing spars. This poses some issues as the spars are tapered (including the IDs) which Im thinking would be best solved by using solid carbon rod sized to the maximum OD fittable, and wrap carbon rovings around each side of the join to fill the gap caused by the taper. Ill have to think about it some more before I make a final decision.

UPDATE!! 10 September: Benno and I decided to get stuck into this wing bagging, so off we went. The photo below shows the carbon tape 3Med to the leading edge of the wing core ready for the layup to be placed on top.

As the wing will be held on with bolts, and will have to survive DS speeds and forces, I decided to go with solid pine blocks for the wing bolt mounts. They were shaped to the profile and then epoxied in and spackled. I also imbedded the servo leads and allowed some extra lead to be placed into a "bay" at the root on the underside, which will be dug out and used to connect to the receiver. This will save cutting through the nicely painted surface after bagging.

Below are the top mylars taped at the root ready for the layup, which (after I changed my mind) consisted of 3/4oz glass veil, 2x 6oz glass (1 at 45 degrees bias), 200 gsm carbon and 168 gsm kevlar bracing across the root, and kevlar strips for a live hinge. It should be very strong. You cant see it, but under that yellow paint are 2 red windtips and a red "dapple" effect over the yellow. Hope it comes out ok!

Its still in the bag at the moment (as I stare at the clock impatiently) so its just a matter of waiting now.

Well here it is! It came out almost perfect. Just need to remove the flashing and trim up the leading and trailing edges. Here it is, straight out of the bag with the mylars still attached.

Just need to join and sort the mounting for the V-Tail and drill the holes for the mounting screws for the wing and the airframe is complete. After that....radio installation.

I have decided to name it the Adrenalin, as Im expecting this machine to be a handfull, especially with hot landings!

Well I maidened the Adrenalin this afternoon in a 17 to 20 knot southerly at the water tower (Hickson Street).

After a pre-flight check, I told Ben to give it a toss. It immediately started gliding out from the ledge and required only a few clicks of up trim and 1 click of left aileron before it climbed out into the distance. After messing around a little on half rates, I decided to go 100%, which it handled easily due to it being nose heavy. It has a very ample roll-rate (although not axial yet) and the elevator is adequate but a little spungy, which should both improve when I dial in the CG. The energy retention of the Adrenalin is just awesome and it readily climbs out back to original height after a beat up across the face of the slope.

Man does this thing eat sky! It took several attempts to land it before I finally got it down. I tried a few times using spoilerons but it just blasted through the landing zone back into the lift for a go-around. Ill have to increase the amount the spoilerons rise I suspect. I currently have them set at 30%.

I managed to land it finally after flying below the slope and washing the speed off crabbing across the face of the slope, then just plopped it down on a grassed area without a scratch!

Im totally stoked with the results and with a little tweaking, I know this thing is going to be ballistic on the dark side.

The Adrenalin is completely sorted after dialing in some dual rates as it was just way too sensative. That was why it was so hard to fly. Anyway, it has now been DSing many times and today its fastest detected speed was 114mph (184kph). It was much faster up higher where the radar couldnt pick up its speed. If only we had a Pro Stalker......

DS Project (Adrenalin)