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Old Nov 20, 2011, 01:40 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,532 Posts
Build Log
SEMFF StingRay with Plans, Build Guide, and Video - Faster, More Furious, and Fun

I just want to start by thanking JHTitan (Funbat designer) and Dr. Sandy Frank (F&F designer). I have built both of these planes, and both are outstanding flyers.

Our group of flyers have really had a great time flying combat with our WWII fighter profile and semi-profile SEMFF Combat Planes. We have been successful at using our current power system, that being the 1700 Kv Blue Wonder, Turnigy, or KEDA clones of the Blue Wonder, and 2 9g servos. Bz1mcr, the propietor of www.strongrcmotors.com has been there for us as well, spending his hard earn retirement cash stocking motors, servos, batteries, and propellers to keep us up and running. Special thank you to Don.

Not wanting to change to a new or different power system led to building the F&F and Funbat with this set up, even though they were designed for a bit more power. The lighter power system reduced the overall weight and made them fly very well with the lower wing loading.

However, I can never leave well enough alone. Looking at those designs I knew I could use the concepts presented there and come up with even better performance. There were a few design criteria that I wanted to meet.

1. Eliminate the nose moment in the fuselage. This always seemed a troubling area for breakage. So I put a swept leading edge all the way to the motor mount The new LE now intersected the old mid way out on the span, which kept the CG near the same position.

2. Eliminate the horizontal stabilizer and elevator. This just saves weight and reduces drag. An elevon plane is as easy to control and can be significantly more manuverable.

3. Minimize the fuselage for less weight and drag. I could have made it even more minimal, but I wanted some asthetics, at least in my eye. This made putting the battery in the same plane as the wing a neccessity, but also reduced the parasitic drag.

4. Keep the two servos and mount flat in the wing. Two layers of foam is sufficient to streamline and mount them.

5. Battery must mount over the CG.

I introduce to you the SEMFF StingRay.

Specifications:
Wingspan - 32"
Over all length - 18"
Wing area - 248 sq. in.
Weight - w/2s = 7 oz and 3s = 8 oz.
Motor - 1700 Kv Blue Wonder or equivalent
Propeller - GWS or APC 7x6
Servos - 9g or equivalent
Batteries - Tested with 850 mAh 2s Turnigy NanoTech and 750 mAh 3s Rhino. Will accomodate up to 1300 mAh 3s.

Control throws:
Hi Rate - Elevon up 3/4" Elevon dn 3/4" 50% expo
Lo Rate - Elevon up 3/8" Elevon dn 3/8" 50% expo
Nuetral setting is straight and level.

I had to use an APC prop and 1.25" Dubro Electric spinner to bring the CG into spec on the prototype, but the plans have the servos move forward 1/2" to correct that condition and allow for use fo the less exspensive GWS prop.

Flight Performance:

She has already seen combat duty and has a couple of scores to her credit. When using the comparable power systems this bird is lighter, faster, and more agile than the F&F or Funbat by a significant margin. She does not twist out of tight high G manuvers. On 2s she is a solid performer outpacing the other planes. I would run at 3/4 throttle to stay even with my opponents. On 3s its a rocket ship.

I was all smiles on the maiden flight once she was trimmed out. She is also a stout bird. My only repairs have been to replace the propeller and reglue the firewall. Then I modified the nose design to accept the left over CF tube from the spar to be embedded into the nose of the fuselage through the hole in the firewall. They nearly the same size. This carries any impact loads further back into the fuselage. Have not loosened the firewall since then.

This may be the combat or fun model you have been looking for. it is easy to build and fly, and has some stly'in lines.

Kits are available for immediate shipment. They are $26.99 each, and include CNC cut foam parts, 30" 5mm carbon tube spar, 2 meters of .051" carbon rod reinforcement, laser cut 1/8" plywood firewall, and laser cut 1/16" plywood control horns. To order visit www.kenscadmodels.com

Build guide and kit details are here.

Demo video flight

Ken


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Last edited by dz1sfb; Nov 05, 2012 at 01:33 PM. Reason: Added build guide pricing and shipping details
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Old Nov 20, 2011, 01:41 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,532 Posts
Video is here. Same as the one from Vimeo, except this one is higher definition.

Ken

StingRay Demo Flight.MOV (3 min 43 sec)
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Last edited by dz1sfb; Jan 06, 2012 at 01:00 PM. Reason: Added video
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Old Nov 22, 2011, 08:04 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,532 Posts
Regarding kits, there is shipping costs as well, about $7. Thinking about breaking the wing into smaller parts to enable lower cost shipping.

Ken
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Old Nov 23, 2011, 10:24 AM
ExPat
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Spain, Murcia, Mazarrón
Joined Apr 2010
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That's a very nice an unusual looking plane Ken, no one else I know has anything that looks like that, I gotta have one. Looking forward to the video.
Andy
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Old Nov 28, 2011, 07:11 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,532 Posts
Kit production temporarily on hold for quality control issues. I will let you know when were back up and running.

On a better note, I got to fly this plane indoors this past Sunday. Put a small (350 mAh) 2s battery in for an AUW 5.8oz for a 3.36 oz per sq. ft. wing loading. She flew around the soccer arena very nicely. Smooth easy turns without any stalling tendancies. It generated alot of interest.

Sold the backup model there.

Ken
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Old Nov 28, 2011, 07:51 PM
beemerdon
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USA, NC, Charlotte
Joined Nov 2009
787 Posts
Ken, I hope you get production up and running again soon; I really like this Stingray. I just started building the Skyray from 6mmflyrc and maybe I shouldn't say this in public, but the quality of your kit (the Spitfire I got a couple of weeks ago) is much higher than the laser cutting on the Skyray. Hope you get it all sorted out soon.

Don
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Old Nov 28, 2011, 09:02 PM
RC Adddict
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Canada, BC, Williams Lake
Joined Jan 2010
4,266 Posts
Having a problem with the ironphlat ken ?? Its cut alot of kits maybe it wants the christmas off
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Old Nov 28, 2011, 11:33 PM
Foam is where the heart is
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Australia, NSW, Como
Joined Aug 2010
2,241 Posts
I was seriously thinking of building the funbat but now I just have changed my mind.

I have all the bits but will build from 6mm depron. My only concern is the strength of the tail. Depron being as brittle as it is this may be a weak spot.

Love your work Ken and I'm sure this one will be a real beauty.
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Old Nov 29, 2011, 03:41 AM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,532 Posts
Brett,

Applying the carbon rods as outlined in the plans be enough. I am going to make one from Cellfoam 88. It is much like depron. Testing to see if it is the foam or the machine that is causing the problem.

Ken
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Old Dec 01, 2011, 09:47 AM
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Virginia Beach, Virginia, United States
Joined Jan 2004
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Any chance a picture of where the nose tripler and fuselage doubler are placed? I have a pretty good idea but just want to be sure. They are not shown on your sketchup picture.

Looking forward to getting this one finished. About to mount all the electrics.
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Old Dec 01, 2011, 10:34 AM
beemerdon
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USA, NC, Charlotte
Joined Nov 2009
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I printed out the plans and I think I will build this out of some 6mm Depron I found in the garage. Will I have to adjust the tabs and slots to fit the Depron vs the blu core?

I have used Cellfoam 88 and liked it. It, like Depron, just seems stronger than the blu core foam. I usually don't even bother with carbon except for the main spar.

I got a Spitfire kit from Ken and ended up building the wing, tail, and center fuse section out of Depron and put the blu core parts on the shelf as spares.

Don
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Last edited by beemerdon; Dec 02, 2011 at 07:54 AM. Reason: spelling
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Old Dec 02, 2011, 06:57 AM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,532 Posts
Quote:
Originally Posted by pylot2b View Post
Any chance a picture of where the nose tripler and fuselage doubler are placed? I have a pretty good idea but just want to be sure. They are not shown on your sketchup picture.

Looking forward to getting this one finished. About to mount all the electrics.
Yes I can, and will, but in simple terms, they mount up tight to the firewall /vertical and horizontal fuselage juncture.

Ken
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Old Dec 03, 2011, 03:14 AM
dpf
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Cambridge UK
Joined Feb 2006
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Looks great ... will have to have a crack at this one ... another on the list ;-)

Anyone tried a rudder on this yet ?


Cheers

Adam
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Old Dec 03, 2011, 08:53 AM
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Virginia Beach, Virginia, United States
Joined Jan 2004
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Quote:
Originally Posted by dz1sfb View Post
Yes I can, and will, but in simple terms, they mount up tight to the firewall /vertical and horizontal fuselage juncture.

Ken
That's what I thought. Going to finish mine today hopefully.
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Old Dec 04, 2011, 08:50 AM
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United States, FL, Mary Esther
Joined Jun 2008
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My airframe's done except for painting, hope to put the electronics in tonight. It's made up from Lowe's FFF foam covered with paper coffee filters stuck on with thinned MOD PODGE from the local A.G. Moore craft store to provide a tough outer skin. No rudder, I wanted to keep it light and simple. I will put in some differential controls throws. Most flying wings fly a lot better with more up than down ailevons.
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