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Jun 22, 2007, 08:00 PM
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sloper steve's Avatar
That is an awesome design! I've wanted a flying wing but with the elevons tilted how this ones are to correct some of the adverse yaw. The canopy is so sleek!
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Jun 24, 2007, 08:43 AM
where are our jetpacks!
lenniegordo's Avatar
Thread OP
Sorry for not replying guys.
I posted this along time ago and not to many people replied and I have not been back to rcgroups in some time as I have been to distracted with pilot lessons.

MADFX that is one good reproduction, well done glad to hear that if files well.

I hope at leased I got the CG right for you. I hate plans that get it wrong. Yes the wingspan on my final plane was less than the plan, but this will not effect the stingray one way or the other.
I actualy never mesure where I cut the tips off I just do it by eye.

I angle the fins at the top just to make it look cool, like an f15 they are square to the londitudainal axis NO TOE OUT - that will just make drag in straight flight you donít want that.

Danjaun looks like with all that foam around your battery youíll end up with a flying ball of flame, might want to do away that. BTW I have flown the stringray with a 2000 3cell and it took the weight well


kevingill the root core is about 1.6cm but it really depends on how much you bend it. It does not suffer from a lack of lift so I would go for less drag keep the root core small, between 1.2 to 1.7cm.


Iím wraped that people have made my Stingray! show it off guys itís a great flyer I would love to think that heaps of people out there were flying my plane.

Cheers
Jun 24, 2007, 12:19 PM
Huh?! well waddayouknow!?
that little foam wrapped thingy is my berg 4.lol but appreciate the concern.
Jun 24, 2007, 09:35 PM
where are our jetpacks!
lenniegordo's Avatar
Thread OP
oh yep sure that's way to small for a lipo
Jun 25, 2007, 12:50 AM
RC Addict
anatoly's Avatar
I just finished one of these earlier tonight. Lennie, thanks for an easy and quick build!

It looks like somehow I wound up with a bigger gap between the folded wings than in the plan, so the fuselage is a bit wider but hopefully that shouldn't prevent it from flying. Also I haven't picked a color scheme yet; my wife likes the clean simple look with the gray fins and says I should just leave it unpainted, but that doesn't look quite right to me. I'll probably do a Sharpie paint job on it after the maden.

Here are the specs:

30" WS, all 2mm depron construction with 3mm depron elevons and 6mm gray depron tail fins.

Hextronik 24g 1700kv brushless motor
Hobbywing Pentium 10A ESC
2x Hextronik 5g servos
Berg Microstamp 4L

AUW 5.2 oz w/o battery. I will be maidening it with a 3s600mAh battery (1.9 oz), for a total AUW of 7.1 oz. There is plenty of room up front to move the battery around to get the balance right.

The drive system is going to be the big question because I'm running the new Hextronik motor. On my thrust stand with a 3s battery, it produces 7.0 oz thrust @ 6.7A with an APC 5x5 prop, 9.4 oz thrust @ 7.08A with a Gunther 125mmx110mm prop, and 12.1 oz thrust @ 5.68A with a GWS 6x3DD. I don't have a tach at the moment (I'm still waiting for it to arrive) but another guy in the power systems forum measured the pitch speed of this motor with the APC 5x5 at around 69 mph pitch speed; if I can get this plane going anywhere near that fast, that will be fast enough for me. I have a feeling that the APC will be the fastest prop, but I'm still waiting for my tachometer to arrive so I can measure rpms and figure out the pitch speed of the other props. In any case I will try to actually fly all of these props since I have them on hand.

Hopefully I will have a chance to maiden it sometime this week and will be back with a flight report.
Jun 28, 2007, 09:47 AM
RC Addict
anatoly's Avatar
I'm surprised this thread has been so quiet, because this is an awesome plane and I think more people should build one. I finally got a chance to maiden the Stingray at our local park this morning, and I must say WOW I'm impressed. The only problem is that our park is pretty small (just a soccer field and a baseball diamond) so I had to keep it below half throttle just to stay within the park but the Stingray flew so smooth and stable with the 5-8mph wind, I'm definitely going to try it on a windier day at a larger field and see how it handles.

I added a little 6mm gray depron launch handle on the bottom, so getting it in the air was not a problem at all. At about half throttle it still felt like it had a tendency to nose down just a little, so I had to give it a few clicks of up elevator to compensate. Otherwise it flew perfectly straight and had no bad tendencies that I could tell. Turns were no problem at all, very smooth. Rolls seemed a bit slow, but I was only doing them at half throttle so I will try it again when I get a chance to open it up at our weekend field. If it's still slow, I may have to reduce the expo on the ailerons and will consider increasing servo travel. Also I may experiment with cutting down the v-stabs a little bit. The power-off glide is really impressive as well; I actually had a bit of trouble getting it set up for a landing because it was gliding so well and I kept overshooting the landing spot. I just wish my actual landing was a bit better, but it will only require a very minor nose repair.

Overall, two thumbs up on this one. Fast build, flies great. Since I didn't crash it, it may be time for a Sharpie paint job...
Jun 28, 2007, 06:55 PM
where are our jetpacks!
lenniegordo's Avatar
Thread OP
Anatoly, yep she's slippery and takes along time to lose speed (allot more so that a stryker), I actual went to a glider comp a while ago and did some laps on the course with the sting ray and she held up well against the gliders the club members have.

Also in my launch instruction I talked about trimming up because it's a Delta wing it needs that stability., If you make the wing symmetrical you won't need to do that so much but if you have a flat bottom you will need quite a lip upwards. (also keep the cg forward on the first fly)

Anatoly Your body looks just right I don't think it's wider at all,, in my first build which you guys did not see, my nose was exactly the same, but it broke off on landing, that's why I came up with the solid blunt fome nose tip, which also help cooling..

One tip I for got to add to the build instructions is if you want a symmetrical wing it's a good idea to score 2 lines with a pen along the line of your carbon spare, that allows the bottom of the wing to curve more when you fold it.

It's a testament to the sting ray that so few people have build it and have so much success with it, I'm very happy
Last edited by lenniegordo; Jun 29, 2007 at 09:10 AM.
Jun 28, 2007, 09:34 PM
where are our jetpacks!
lenniegordo's Avatar
Thread OP
Quote:
Originally Posted by anatoly
Rolls seemed a bit slow
your ailerons look a little small? with bigger ailerons you'll have much more control you should be able to fly a 25* angle of attack with out stalling (even doing a roll) and with just the right amount of power and angle of attack you can slowly drop the stingray out of the sky for a vertical landing. Yes straight down!

I don't uses any expo, I did at first but I like the crisp rolls you get with out


Quote:
Originally Posted by anatoly
I'm definitely going to try it on a windier day
the stingray loves wind, about all that happens is a little bum wiggle when a gust hits it, I ignore wind totally I have flown in 30 knots of wind. But hay doesnít do it till you used to flying it. (wind helps shorten a glide approach)

Quote:
Originally Posted by anatoly
I had to keep it below half throttle just to stay within the park
You could always fly straight up... lol
Last edited by lenniegordo; Jun 29, 2007 at 09:09 AM.
Jun 28, 2007, 09:41 PM
where are our jetpacks!
lenniegordo's Avatar
Thread OP
Triva
the StingRay is named in honour of Steve Irwin. Being a design from Down Under. It was conceived just after his death, and by coincidence I was swimming at the beach and dived in to a wave to find a stingray swim off just beneath me. it was then that I had the name for the StingRay... helps that it looks like one to.
Last edited by lenniegordo; Jun 29, 2007 at 09:11 AM.
Jun 28, 2007, 10:55 PM
RC Addict
anatoly's Avatar
Quote:
Originally Posted by lenniegordo
your ailerons look alittle small? with biger ailerons you'll have much more control you sould be able to fly a 25* angle of atack with out satlling (even doing a roll) and with just the right amount of power and angle of atack you can slowly drop the stingray out of the sky for a verticle landing. Yes straigt down!
I actually had cut them twice the size at first, but then I was looking at everyone else's build and mine seemed too big, so I cut them down. I have great control with these elevons, tight turns are no problem, but just need to work on the roll rate. I didn't expect too much at half-throttle anyway. It's easy enough to make them bigger if necessary, but I have to try them at full throttle first to see how the plane responds.
Jun 29, 2007, 09:13 AM
where are our jetpacks!
lenniegordo's Avatar
Thread OP
As long as your happy thatís cool, just that mine whips around at any speed...
Jul 01, 2007, 12:04 AM
where are our jetpacks!
lenniegordo's Avatar
Thread OP
Quote:
Originally Posted by sloper steve
That is an awesome design! I've wanted a flying wing but with the elevons tilted how this ones are to correct some of the adverse yaw. The canopy is so sleek!
adverse yaw good question so I went for a fly to have a closer look at that one.

The large fins are there to stop to much adverse yaw (it's not necessary for stability, if you want a stingray that skids allover the place you could have the fins 1/4 the size). and really there is so little wing loading that adverse yaw is minimal. But there is some - notably causing it to rotate slightly off the longitudinal axis at high angles of attack.

In a spinning vertical dive or clime the stingray roles dead center around it's longitudinal axis since in this position there is no induced drag at any speed.

however in level flight the stingray rotates off center but perpendicular to the longitudinal axis (more accurately it's flightpath) by about 4cm at say 20mph since the induced drag is highest at this point. But at 80mph you can hardly tell it's only about 1cm.

Since there is room for various wing width in the design and build I would imagine this would vary. I have built 3 Stingrays and all had slightly different flying caractor

BTW there is nothing stopping some one putting 1/2 size fins on the wing tips it would reduce drag and have a better moment effect on the flight path, as it would have a longer leaver arm to the cg. I think I'll do that on my next vertion (wont look as cool though)
Jul 03, 2007, 01:00 AM
Micro Zippy
jconwell's Avatar

Mini Stingray


I'm working on a mini stingray, using folded 2mm deupron to create my airfoil. Its got a 17" wingspan, and is 11.5" in length. I'll be using Plantraco recievers and a micro SS motor with a 5035 carbon fiber prop.

Here are my build photos so far.
Jul 04, 2007, 07:49 PM
Former pattern/IMAC champ
Quote:
Originally Posted by danjaun
that little foam wrapped thingy is my berg 4.lol but appreciate the concern.

Hey Dan Man!

Just saw you on channel 3 news in front of a certain Thai food restaurant talking about one of the employees with Hep A and such. When are we gonna fly indoor at that school again???

Later,

Paul
Jul 18, 2007, 04:35 AM
where are our jetpacks!
lenniegordo's Avatar
Thread OP

Fun with the Stingray


I went away on a holiday with some family & friends. I wanted to be able to let others join in the fun of flying an RC models. So I got this toy shuttle and tricked it out with servos and a receiver. and mounted it on my bomb dropper. The idea was that I could fly the stingray up and drop the shuttle from safe height alowing some one else to glided it down. it worked really well I would fly it up and others would fly the shuttle down, up and down all day what a blast.


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