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Old Dec 05, 2010, 12:33 AM
Team Park Pilot - Airborne
OzparkPilot's Avatar
Australia, NSW, Sydney
Joined Nov 2006
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Self designed SFG`s for my TT Katana - want YOUR help please !!

After flying my Thunder Tiger Katana G2 for a few month I`m loving it. I wanted to use it as a testbed for a few mods and I would like to start with some SFGs built from CF. So, looking for help from people who have done this - Here are a few picture we took of the Katana.... Its a 45` Span.

Have a few questions please:

1) What shape should they be ?

2) Is CF the best way to go ?

3) How should they be mounted ?

4) Would " mini SFG on the stabiliser add an benifit to this mod ?

Thanks guys. Will keep updating the project.
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Last edited by OzparkPilot; Dec 05, 2010 at 12:39 AM.
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Old Dec 05, 2010, 01:23 AM
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grubby's Avatar
Denver Colorado
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Take a look at the Precision Aerobatics "vortex generators".
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Old Dec 05, 2010, 01:44 AM
Team Park Pilot - Airborne
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Sure..PA are next door to me in Sydney. Want to see some other mssurements to help me before I cut the CF.
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Old Dec 05, 2010, 01:56 AM
IMK
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Perhaps have a look at post 6337 in the PA Katana MD thread for some inspiration.

http://www.rcgroups.com/forums/showt...g#post14396772
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Old Dec 05, 2010, 02:02 AM
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Las Vegas, NV
Joined Nov 2009
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If you ask me, cutting carbon fiber SFGs will be a royal pain in the A**. I'd recommend 1/16 - 3/32 in (1.5 -2 mm?) plywood. Reinforce the edges or tips of the tip plates with CF if you want. A recent issue of Model Airplane News has a picture of a guy's plane with clear plastic tip plates. He drew simulated angles on them so it looked kind of scale. However you do it, I hope they give you what you're looking for.
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Old Dec 05, 2010, 02:02 AM
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Melbourne, Australia
Joined Aug 2007
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Go for something like the 3DHS Velox SFGs. I've seen them fitted to a PA Extra 260 and it totally transformed the flight characteristics.
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Old Dec 05, 2010, 08:51 AM
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Quote:
Originally Posted by IMK View Post
Perhaps have a look at post 6337 in the PA Katana MD thread for some inspiration.

http://www.rcgroups.com/forums/showt...g#post14396772
Whoa, didn't think my little home made SFGs would be held up as an example.

When making SFGs, you need to consider what you want out of them. Making the go all the way to the trailing edge of the aileron means they also act as fences and help stabilise the wing rock in high alpha. Good examples of this are the FuntanaX, the 30cc QQ Yak, Extreme Flight Extra. Also, for the Katana MD, leblanc did some other interesting VGs in 2007, you can search for his on that same thread, and there is another of mine there also.

If you want to make VGs like the PA ones, you can easily make them from 0.5mm carbon sheets and cut them out using lexan body scissors (the ones the car guys use to cut their bodyshells, and no carbon dust to worrk about). Thats what I did to make the silver VGs on the VG Mania MX here: http://www.rcgroups.com/forums/showp...postcount=3787

My SFGs on the KMD were all basically just based on guesswork and looking at others designs. But thats half the fun, experimenting. Good luck with yours.
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Old Dec 05, 2010, 09:37 AM
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I used a set of spare SFGs from a 3DHS Velox on my Yak. They were too long, so I lined up the back to fit flush with the rear of the ailerons and whacked off the front of the SFG flush with the leading edge of the wing. For the SFGs on the tail I simply resized the big ones on my computer.


I'm sure in the end that extensive use of wind tunnel data and cad cam computer analysis would give you the perfect SFG, but eyeballing it will probably get you close enough. The only part you have to be careful of is to make sure they are identical to each other.
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Old Dec 06, 2010, 01:25 AM
Team Park Pilot - Airborne
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Australia, NSW, Sydney
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Thanks guys - Doc, I had not seen anyone use them on the Stab before so I`m glad that you have had success here. How have they helped Harrier and KE flight ? and do the stab SFGs change things one more ? Many Thanks. This is going to be fun !!
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Old Dec 06, 2010, 09:53 AM
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United States, PA, Lancaster
Joined Jun 2003
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If you have access to 3mm Depron foam, it's fantastic for experimenting. We keep a supply of it and use it to try different shapes during testing. On SFG's, I highly recommend trying at least a couple of different sizes in depron before spending the time to build balsa or carbon.
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Old Dec 07, 2010, 01:02 AM
Team Park Pilot - Airborne
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Australia, NSW, Sydney
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Yes ok thats the plan now.. Thanks. What I really want to find out are how differant shapes make the plane behave. Also I wonder if the CG will be affected not taking into account the actually weight ? For example. will the additional drag produce a nose high attitude ?
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Old Dec 07, 2010, 08:33 AM
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Quote:
Originally Posted by groovejet View Post
Go for something like the 3DHS Velox SFGs. I've seen them fitted to a PA Extra 260 and it totally transformed the flight characteristics.
Care to elaborate a bit on how it changed the flight characteristics?

Thanks,

Jakub
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Old Dec 07, 2010, 12:29 PM
Half way there
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USA, FL, Ocoee
Joined Sep 2008
1,203 Posts
To improve high alpha stabilty I follow the design of spill plates on race car wings. Basically signifigant area at the leading edge and possibly a little a ahead to capture flow, pressue or whatever.
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