I am happy to introduce not only a new kit, but plans for the folks that love to build from paper templates, the latest version of the SEMFF StingRay, StingRay 3.0.

This new interation has some significant design improvements and more organic looks.

Changes include;
- Further aft center of gravity.
- Longer elevons.
- More central servo location.
- Sexy trailing edges.
- One degree of downthrust

Flying characteristics impacted by changes;
- Easier to build inside the cg range without having to add ballast or spinner.
- More pitch authority at low speeds.
- Less rolling moment inertia which make for crisper rolls and protects the servo from impact by placing them behind the prop arc.
- Smoother roll response.
- Pulls level through power range.

Plans have written instructions and will be accompanied by a build guide.

Ken





Testimonial - https://www.rcgroups.com/forums/show...&postcount=143

Ken:

Thank you for the beautiful plans. This is a very good looking aircraft.

Warm regards;

Dave-

Ken:

Whoo Hoo! I just received my new StingRay 3.0 kit in the mail. It was packaged well with all the goodies needed to build. Glue it up, add electronics and paint and voila!. Hope I get time soon to build it. Beautiful job on the cutting. Quick service too.

Warm regards;

Dave-

Originally Posted by foamdave

Ken:

Whoo Hoo! I just received my new StingRay 3.0 kit in the mail. It was packaged well with all the goodies needed to build. Glue it up, add electronics and paint and voila!. Hope I get time soon to build it. Beautiful job on the cutting. Quick service too.

Warm regards;

Dave-

Right back at you Sir!

Ken

Ken, Love the upgrades. Very nice.

I have a question about the pictures above. It looks like you have wrapped 3m extreme around the nose, and then mounted your firewall on top of the tape.

I always have trouble with adhesives sticking to tape. Can you tell me your technique?

I've had trouble with the fuse separating from the wing in that very spot as well, so I can see the need for good tape here.

Thanks, and hope to see you this evening for COMBAT!!!!

I knew I had to build it as soon as I saw how well handled - pure and fluid. Pretty excited that it is finally finished

$Tree foam build with colored packing tape covering
265 gm without battery
L2210 1400Kv 210W
F-30A flashed with SimonK (everything just runs cooler) pulls about 25amps on a static test
APC 0806E prop

Hope to fly it tomorrow. I think it should go pretty well with a 1300mA 45-90C battery being an AUW of 380 gm.

Ed

DollarTree foam, 16 gram motor w/5043prop, HXT500 servos, AUW with 2S 300mA battery 100g. I Built this one in less than 3 hrs.

BL Stingray (3 min 58 sec)

Originally Posted by vastsky

I knew I had to build it as soon as I saw how well handled - pure and fluid. Pretty excited that it is finally finished

$Tree foam build with colored packing tape covering
265 gm without battery
L2210 1400Kv 210W
F-30A flashed with SimonK (everything just runs cooler) pulls about 25amps on a static test
APC 0806E prop

Hope to fly it tomorrow. I think it should go pretty well with a 1300mA 45-90C battery being an AUW of 380 gm.

Ed

Nice!!!

Ken

Well got a new StingRay built up over the last week. Been needing one for demo and shows. Thought I would post its picture here.

Ken

Geez Louise. This is what I've been looking for. So glad I finally found it. I'll be ordering VERY soon.

Quick question. I'm tracking down the 1700kv blue wonder, what weight? I see some that are 16g and others that are 24g. Can I use the the HK 24g motor? https://www.hobbyking.com/hobbyking/s...idproduct=5208
If so, do you still recommend same 7x6 prop, and if so again... What esc do you recommend?

Thanks Ken!!

Originally Posted by Loppy

Geez Louise. This is what I've been looking for. So glad I finally found it. I'll be ordering VERY soon.

Quick question. I'm tracking down the 1700kv blue wonder, what weight? I see some that are 16g and others that are 24g. Can I use the the HK 24g motor? https://www.hobbyking.com/hobbyking/s...idproduct=5208
If so, do you still recommend same 7x6 prop, and if so again... What esc do you recommend?

Thanks Ken!!

The 24g version is what you want. Although it can easily handle a 2208-12 which is a 36g motor and 1800 Kv (shown in pic above). Stay with the 7x6 prop in either case.

Ken

Right on Ken, thanks so much. SOOO mad, I just blew my RC wad for the month before I found this. I'm frantically trying to sell stuff to get my orders in. haha... Cheers!

Been having fun with this plane!

Mine has a strange tendency to corkscrew exit out of the completion of a tight loop, typically off to its right. Been thinking about this and unsuccessfully tried the following to shed this behavior.

1) Heavier gauge pushrods to eliminate flex. Doing a loop is a "push" on the rods and I thought one of them may have been flexing.

2) In-fill the elevons curvy profile. I thought that it may have needed deeper control surfaces at the elevon tips to lend greater authority, so I added on about 1 1/8" depth at the tip to 0" at the root of the elevon. Still corkscrews out.

3) CG is pretty much spot on recommended, mostly thanks to the excellent plans!!!

It only corkscrews exiting the loop if it is a tight loop. A larger loop yields a nice straight exit. Perhaps my throws are too great and causing control surface turbulence and this resulting behavior?

Ideas?

Thanks,

Ed

Sounds to me like you have intended or unintended differential in your elevon throws at max. Match servos dead center, adjust rods so that elevons are dead even. Make sure sub trim, expo and rates are matched 1 for 1 and see if that helps.

Or you could just have one servo that doesn't throw as far physically as the other. Seen that too even in hi end stuff.

Originally Posted by Loppy

Sounds to me like you have intended or unintended differential in your elevon throws at max. Match servos dead center, adjust rods so that elevons are dead even. Make sure sub trim, expo and rates are matched 1 for 1 and see if that helps.

Or you could just have one servo that doesn't throw as far physically as the other. Seen that too even in hi end stuff.

Thanks Loppy!

I have examined it for exactly this on the bench and elevon deflection appears really equal one side compared to the other. I thought that this corkscrew exit might be a characteristic of the plane.

I am using the HXT900 servos. I install the servo arm on spline shaft on the best "center" achievable after centering the servo with a servo tester. Then I sub trim it so the arm is dead center and go ahead and bend up the pushrod, installing it for neutral elevon position. I try to use the maximum usable servo throw (for finer servo resolution) balancing this with the right hole in the elevon horn for reasonable range of deflection for the sort of plane it is.

I do believe you are right though that this setup is creating differential. Perhaps by attempting to have greater servo resolution combined with the typical inconsistent servo centering one servo is pushing just a bit less than the other giving me this corkscrew finish. I may reduce the servo throw range and resulting resolution and see if this helps. I'll figure it out. Otherwise it is a fun plane!

Ed