|
Post by thevon on May 30, 2007 15:29:59 GMT 10
I got a Scorpian kit from Glenn (Zipper) and altho I'm in no hurry (took opportunity of his visit to Bris to get it freight free) I have started to dabble with it. Here are a coupla pics of the wing profile and the way the spars go together. I thought it was great the way there are holes cut thru the wing for the spars - very easy install them and glue them using PU glue. It can be built as a basic combat wing but I'm going to round the tips and put a tail boom on, to make it faster and more DS-able. I'm going to put a couple of GWS metal gear BB micro servos in ($30 ea) and I have some MZK Berg type tiny receivers coming next week, so I reckon I'll put one of those in. They're no more expensive than other receivers but have so many benefits it'd be crazy to buy anything else. By the way I did a quick mod on the Duck to give it a new lease on life too - removed winglets and covered tips with light signwriting vinyl, and made a tail setup like Sean's, using 5mm coreflute with a carbon spar poked tightly into it.
|
|
|
Post by thevon on Jun 9, 2007 19:21:44 GMT 10
I've finished the Scorpian so here are a few photos from building it. I used an MZK Berg-type receiver which is absolutely tiny, but full range and with the DSR transmitter fingerprinting. Servos are GWS metal gear BB micros buried fully and I used Golden rod control linkages, buried into the wing. Using the golden rods enabled the servos to be located well forward, behind the spar, and the flexible rod extends well into the length of the elevon. Batteries are Sanyo 2700 mAh, soldered up myself with 2 each side. Covering is with heat film - the yellow is "Orastick"with adhesive backing, and the top is Profilm. Sprayed with super 77 and let dry before ironing the film on, or the Orastick won't stick if the glue's tacky. Also after covering, I put strips of "Clear Guard" paint protection film on the leading edge. It's used by auto people to stick over paint to protect it from stone chips etc. Very hard to cut/rip. We got some for a new racing bike and had some left. One other benefit of this is it holds down the edge of the heat film to stop it lifting. Also this time I refined the fin mount, using a smaller piece of 5mm corflute stuck on with double sided tape - the idea being that it will rip off before the carbon rod breaks. Seems to work well. Like everything I do, it's all rough but strong, and it only took me about 3 times as long as I expected. All up the plane weighs around 720gm, including 55gm of lead in the nose to balance it. The instructions said the CG was 180mm behind the nose but it's actually at 195mm. You can see the spar lines. After gluing spars I smeared the wing with Spakfilla Rapid and sanded it. Showing the tiny receiver, model alarm, and charge jack/switch socket Snugly in place Taping and hingeing done Finished, with some duct tape covering the lead balance for test flights. I'll put some decorations on it later after test flying it on a slope. I'll cover over this plate after test flying.
|
|
|
Post by ezza on Jun 9, 2007 21:01:25 GMT 10
I used Golden rod control linkages, buried into the wing. Using the golden rods enabled the servos to be located well forward, behind the spar, and the flexible rod extends well into the length of the elevon. Very nice Andrew, I have not used or seen this method before. It looks nice and clean!
|
|
|
Post by thevon on Jun 9, 2007 21:20:17 GMT 10
Yeah Ezza, I hate tailbooms coz they break so easily, but they're definitely a lot faster than winglets. I've tried a few methods and saw Sean with this on his Bat. You just build the fin onto some 5mm (or 5.5mm which is a bit tight) carbon rod, which pushes tightly into the 5mm coreflute. YOu can spray a bit of super 77 onto the rod and let it dry, which makes it stick into the coreflute but it'll let go if twisted hard. However I keep breaking the fins and rods so I'm looking for a way to have it let go. I think taping the plate on with masking tape could be OK too.
Glenn uses 3mm carbon rod on his fins, one built into the fin and the other 2 taped either side of it, and they push into 3mm coreflute very nicely. But once you knock them like I do with my many crashes, they come looser and have much more rotational movement than the 5mm rod.
I'm also going to try simply making the whole fin out of coreflute and pushing it on the same way! (5mm coreflute for the plate and for the fin too). It will have more drag but might be useful while I'm trying to get DS'ing experience!
By the way I loved your story about Casino today - a long way to go, but sounds worth it. An amazing story. I had to laugh about the crash with the tree, but I'm glad it was you not me. Mind you I'm still having the same sort of crashes, even when I fly at 40 mph not 113mph!
|
|
|
Post by callun on Jun 9, 2007 22:17:35 GMT 10
What receiver is that you've got there Andrew? Price? Source? Specs? etc
|
|
|
Post by ezza on Jun 10, 2007 1:45:18 GMT 10
Andrew, I might have to try this tailboom technique, as I am rebuilding my old Zagi. I was also referring to the the buried pushrods. Yeah, it is about 1hr 20 minutes from my place to this site. Not too bad, compared with driving up to some of the other ds sites from my place. But yeah, a long way from Brissy.
|
|
|
Post by thevon on Jun 10, 2007 9:32:15 GMT 10
Callun, the receiver is a MZK Profi Penta 5 channel berg type, mad in the Czech republic. I got some from David Leigh of RC Sailplanes.com. Not sure of the price - mine were about $80. I have one spare and can sell it for $80.They're really quite amazing - full range, etc and if you google for "berg receiver" you'll find out about the TSR, DSP and "hold" functions they have. Perhaps I should do a thread on them sometime.
|
|
zipper
> 50
Off The Edge Sailplanes
Posts: 88
|
Post by zipper on Jun 10, 2007 11:19:14 GMT 10
Andrew, Nice build, they only concern is with the way you have installed the push rods. I tryied it once and ended up with about 5mm of slop in the rod You will find that they will become sloppy after a while, as there is a gap in the rod between the inner and outer, that will open and close around the bends. They work much better when they are in a straight line. Did you set the CG at 180mm?
Glenn
|
|
|
Post by thevon on Jun 10, 2007 12:55:56 GMT 10
Hi Glenn - no there's no slop. I thought there would be, but they're good quality old type rods - they're narrower and probably better than some other cheap ones I"ve bought. If you sort of squash the outer into a bit of an oval in the process of bending the curve it makes them tighter (so the oval is higher at the top and bottom and narrower from front to back.
I've been giving it some test throws in the park etc and just found a tiny spot at Bald Hills facing west so I actually got some lift! No the CG is much further back - I got it trimmed with the CG at 197mm.
I really need to get it to a good slope coz it wants to fly fast.
|
|
zipper
> 50
Off The Edge Sailplanes
Posts: 88
|
Post by zipper on Jun 10, 2007 14:45:12 GMT 10
197 is way to tail heavy, it is best at 180. All the scorpians that I have built have been set at 180mm and fly grate straight out of the box. You might not have any slop yet, but it wont take long once you have planted it a couple of times.
Glenn
|
|
|
Post by thevon on Jun 13, 2007 18:06:55 GMT 10
Just found that the left side GWS servo which I put in the Scorpian has lots of slop in the gears. Grrrrrrrrrr. Bugger. The other one is fine. I had to cut the skin and cut the servo out and cut the wires and solder and glue another one in.
I don't think the GWS servos are as good quality as the Hitec HS85MG's I put in the Drongo. They seem to be very strong and have lots of torque but have more free play and are not as fine resolution in the movement.
|
|
|
Post by thevon on Jun 13, 2007 19:06:13 GMT 10
Replacing the servo reduced the slop but it was still excessive and as Glenn predicted, there was slop in the curved control rod. Funnily though, the right one is rigid. I think it was from the Ricochet wing which Alan heat-curved to remove slop, and I think I just bent the left one without much thought.
Anyway - dogged persistence and a stroke of luck prevailed. I have a new set of Dubro plastic control rods never used, and I found that the new clear inners are a bit bigger than the older yellow inners and they make a really snug fit in the old outers! So I just cut a new one and slipped it in and it's rigid. Next time I'll use that combination from the start.
|
|
|
Post by sean on Jun 13, 2007 19:20:25 GMT 10
Hey Andrew, The Scorpian's looking good! I Look forward to seeing it in the air, you certainly got it together quickly . Regarding servos, I've ordered some Futaba S3102s for my Reaper, they're about the same size as HS-85s and supposedly have less slop, and only cost a couple of dollars more each. If you're interested I'll tell you how I get on. Those GWS servos are an attractive price but I'm a little nervous to try them myself. Last night I found some digital mini servos being sold for $20 each from an Australian shop, amazing! I'd be very interested to see if they're any good. You can find them here: www.rchobbyboy.com/store/comersus_viewItem.asp?idProduct=383They're branded "Corona" but after a little searching on RCGroups I found they're branded as "HDX" in the US. Sean.
|
|
|
Post by thevon on Jun 13, 2007 19:58:30 GMT 10
Yep Sean thanks. I was planning to use the 2 extra GWS servos for the Ozprey I'm going to get from Gerard. I guess I'm still hoping they'll do the job. Otherwise I'm hoping not to buy any more stuff for a while. Here's a photo showing the different types of Golden Rods - new Dubro ones on the left and older ?? ones on right. They've swapped the position of the fluting, basically. Aaah, I'm liking my new Olympus E510 digital SLR!
|
|
|
Post by thevon on Jun 28, 2007 21:32:49 GMT 10
Well I've finally got to fly the Scorpian properly! Up at Bald Knob in the NW wind, and I can say that the thing really goes! Quite amazing how quick it is. It was well balanced with the CG about 203mm, just enough back to tuck under sometimes, but generally stable. It's a wobbly plane when flown slowly but only needs a bit of lift and it picks up speed and tracks beautifully once it's hiking. Took it down to the gate and started to play around with DSing and it really got going. It was the first time I "really" got to DS. Sean also got the hang of it with the Bat. More about that in the Drongo - learning to DS thread. The Scorpian's an excellent foamie wing for someone wanting a faster plane than a Bee etc. Glenn was right, it's a great plane to learn to DS with because it really holds its speed and carves well. Definitely happy with it.
|
|