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Modified 1/2a Skyray

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Modified 1/2a Skyray

Post  JPvelo on Tue Sep 02, 2014 5:44 pm

I won't do a complete build thread but I wanted to let everyone in on my current project. I need to build something for the Hobbico fuel test and (hopefully) the next flight time contest. I had a Skyray kit but wanted to improve on the already surprisingly good performance and the aesthetics if in going to be looking at it for five plus hours next year. lol!

I'm adding flaps as an experiment on the sheet wing, and also sweeping the leading edge back. This will move the cg back about 3/4". I'm also adding weight to the front with 1/32 sheeting, so I extended the tail 1 3/4". I cut down the ugly, in my opinion, vertical stabilizer as well. Here's how it looks mocked up:



I will go with a military theme, maybe tan/green camo with sky blue bottom surfaces. Has anyone tried the flat rustoleum colors with high nitro fuel?

Thanks for looking,

Jim
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Re: Modified 1/2a Skyray

Post  RknRusty on Tue Sep 02, 2014 6:41 pm

Jim, my whole Yak-9 is painted with flat white Rustoleum. But then wet sanding and clear Lustrekote made it just as shiny as if I'd used glossy. I fuel tested the plain flat spray on a board and it seemed just as resistant as the gloss paint. Your styling did de-uglify it really well. Looks cool.
Rusty

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Re: Modified 1/2a Skyray

Post  Cribbs74 on Tue Sep 02, 2014 6:59 pm

Hope it works well for you Jim. Looks better than stock that's for sure.

Ron
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Re: Modified 1/2a Skyray

Post  Theo Kleynhans on Wed Sep 03, 2014 6:49 am

That is looking cool Jim.

I wonder what difference the flaps will make on a sheet wing? Hope to get a flight report once it is done. Would love to know how it flies.

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Re: Modified 1/2a Skyray

Post  RknRusty on Wed Sep 03, 2014 10:42 am

Theo Kleynhans wrote:That is looking cool Jim.

I wonder what difference the flaps will make on a sheet wing? Hope to get a flight report once it is done. Would love to know how it flies.

Theo
I don't know, it might turn a loop like it has an axle through it.

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Re: Modified 1/2a Skyray

Post  roddie on Wed Sep 03, 2014 5:50 pm

I'm curious about the flaps Jim. Are they "joined".. or a single-piece? I see what appear to be ply-plates (or plastic "horn-plates"?)on either side.. so I'm guessing they're 2-pc. with a U-bent joiner-wire fitted in. That's a lot of work. If there not attached yet.. you could save some weight with a full-span flap.. and cut a sideways "V"-notch in the fuse at the rear of the T/E slot for clearance.
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Re: Modified 1/2a Skyray

Post  JPvelo on Wed Sep 03, 2014 8:03 pm

roddie wrote:I'm curious about the flaps Jim. Are they "joined".. or a single-piece? I see what appear to be ply-plates (or plastic "horn-plates"?)on either side.. so I'm guessing they're 2-pc. with a U-bent joiner-wire fitted in. That's a lot of work. If there not attached yet.. you could save some weight with a full-span flap.. and cut a sideways "V"-notch in the fuse at the rear of the T/E slot for clearance.  
Roddie,

They will be joined with a music wire horn. The fuselage thins out behind the wing pretty good and I don't want to risk weakening it.

Jim
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Re: Modified 1/2a Skyray

Post  JPvelo on Fri Sep 19, 2014 2:30 am

Should have a flight report tomorrow:
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Re: Modified 1/2a Skyray

Post  Theo Kleynhans on Fri Sep 19, 2014 4:04 am

That looks great Jim.

I hope she flies as great as she looks. I would like to know what the difference will be with the flaps.

Theo
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Re: Modified 1/2a Skyray

Post  roddie on Fri Sep 19, 2014 5:45 am

JPvelo wrote:Should have a flight report tomorrow:

Supe-R-Cool Cool Jim! I like how you did the flap linkage and the solid lead-outs! Clapping The canopies on your models always look great too! What is that you're using to secure the pushrod on the flap-horn?
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Re: Modified 1/2a Skyray

Post  JPvelo on Fri Sep 19, 2014 8:44 am

Thanks Roddie! I use 1/2a set screw linkage thingies from dubro on all my 1/2a stuff:
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Re: Modified 1/2a Skyray

Post  Kim on Fri Sep 19, 2014 9:27 am

OH YEAH !!!!!!!!!!!!!!!!!!!!!!
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Re: Modified 1/2a Skyray

Post  getback on Fri Sep 19, 2014 9:30 am

LOOOOOOKING GOOOOD!! Jim can't wait for the report hope everthing goes well . Eric Very Happy
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Re: Modified 1/2a Skyray

Post  RknRusty on Fri Sep 19, 2014 10:09 am

Pretty cool. I'm curious too about how it flies.

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Re: Modified 1/2a Skyray

Post  pkrankow on Fri Sep 19, 2014 10:31 am

Impressive looking. I hope it flies as well as it looks!

Phil
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Re: Modified 1/2a Skyray

Post  Cribbs74 on Fri Sep 19, 2014 1:22 pm

Great Job Jim!!

I like your style. That nose is long, how is it balancing?
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Re: Modified 1/2a Skyray

Post  JPvelo on Fri Sep 19, 2014 2:03 pm

Flys like a Skyray only smoother. Almost like a built up wing if you don't get to tight on the maneuvers. I think it could square loop with a better pilot. The flap mod is definitely worth the extra effort.  It was a little lean in this and I was stunting in the wrong corner of the wind to get it on camera. That's what led to the 10 point gymnast landing. Only thing hurt was the prop.
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Re: Modified 1/2a Skyray

Post  RknRusty on Fri Sep 19, 2014 2:30 pm

Good flying by you and the plane. I see you've added reverse wingovers to tour repertoire. Yeah, a little lean, you can hear it heat up more late in the flight. You've still got the meanest reedies around. That's moving awfully fast to be doing a square loop.
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Re: Modified 1/2a Skyray

Post  Cribbs74 on Fri Sep 19, 2014 3:28 pm

Looking good Jim!
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Re: Modified 1/2a Skyray

Post  duke.johnson on Fri Sep 19, 2014 5:23 pm

Really nice Jim!!!
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Re: Modified 1/2a Skyray

Post  roddie on Fri Sep 19, 2014 6:49 pm

Nice! It seems plenty responsive even at those high speeds. Are you using a 5" prop? I wonder whether a 6 x 2 or 3 would slow it down 10-15 mph... enough to let you "carve"  your corners more? Were you able to get an average lap-time/mph estimate? I'm curious.. only because I don't know what an average lap-time should be.. for a given line-length for 1/2A "Precision Aerobatics". Do you have any 6" left-hand props you could try? What the heck... a left-hand prop will help with launching.. and pull better in breezy conditions. I'm planning on running a 6 x 2 L/H on my PT19 tomorrow... but it will be on much shorter lines.. affraid
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Re: Modified 1/2a Skyray

Post  JPvelo on Fri Sep 19, 2014 9:18 pm

roddie wrote:Nice! It seems plenty responsive even at those high speeds. Are you using a 5" prop? I wonder whether a 6 x 2 or 3 would slow it down 10-15 mph... enough to let you "carve"  your corners more? Were you able to get an average lap-time/mph estimate? I'm curious.. only because I don't know what an average lap-time should be.. for a given line-length for 1/2A "Precision Aerobatics". Do you have any 6" left-hand props you could try? What the heck... a left-hand prop will help with launching.. and pull better in breezy conditions. I'm planning on running a 6 x 2 L/H on my PT19 tomorrow... but it will be on much shorter lines.. affraid
For cox flying I use a master airscrew 6 x3 cut down to 4.75. I like them to fly fast!

Jim
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Re: Modified 1/2a Skyray

Post  Cribbs74 on Fri Sep 19, 2014 10:18 pm

Thin airfoil likes speed.

Roddie you would be hard pressed to get a 5 sec lap time out of a 1/2A. Although I would love to make that happen for myself.

As it stands when I fly 1/2A I hang on, but bigger stuff I am more relaxed.

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Re: Modified 1/2a Skyray

Post  roddie on Sat Sep 20, 2014 9:06 am

Cribbs74 wrote:Thin airfoil likes speed.

Roddie you would be hard pressed to get a 5 sec lap time out of a 1/2A. Although I would love to make that happen for myself.

As it stands when I fly 1/2A I hang on, but bigger stuff I am more relaxed.


I guess I figured that the idea behind adding flaps to this model was an attempt to improve it's PA capabilities. Maybe it's just too fast with the slab-wing combined with Jim's "hotrod reedies"..  Cool

Jim, how does the flapped version's performance compare to the original design? Let's say you had both versions involved in a combat match.. all else equal (pilot's ability, engine set-up, fuel, props) Do you feel that the flapped version would have an advantage? Does it feel like it turns any tighter or quicker?

I have mixed feelings about the use of flaps for C/L stunt. Do they really help to turn the airplane around it's pitch axis? I would think that a well designed tail-plane moment with adequate span and elevator/stabilizer proportions would handle the job of pitching the model, without the use of flaps. I feel that an un-flapped fully-symmetrical wing works in unison with the models center of gravity when pitch is altered; changing it's angle of attack. Flaps are for generating "lift"... which; when you think about it.. is working against turning the airplane around it's pitch axis. Maybe I'm full of crap... Laughing
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Re: Modified 1/2a Skyray

Post  JPvelo on Sat Sep 20, 2014 4:05 pm

Roddie,
It flys much better with the flaps. Whereas the stock plane mushes through maneuvers like a slab wing plane this grooves much more like a plane with a built up wing.  It's an easy enough mod on a slab winger with a big enough performance gains I will probably to it on all my slab wingers from now on.

Jim
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