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Old Oct 07, 2012, 11:37 AM
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Rob_P's Avatar
Grosse Pointe, Mi
Joined Jun 2005
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Guys,
thanks for the feedback I'm really looking forward to starting this but I have another project to finish first....

http://www.rcgroups.com/forums/showthread.php?t=1747094
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Old Jan 20, 2013, 11:57 PM
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Mel Duval's Avatar
Joined Jun 2001
2,046 Posts
I have a converted outdoor rubber model that looks a lot like the Invader. I put a sub micro servo in the center of the stab and drove the rudders with a single piece of carbon rod. Heat shrink for the connection at the rudders and the z bend arm connection metal bit. Will try to get a pic tomorrow.....
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Old Jan 21, 2013, 03:46 AM
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ohaley's Avatar
United States, AK, Valdez
Joined Apr 2008
14 Posts
I have Leslie Adam's "Torpedo II" short kit from Klarich and would like to build with RC Assist. Any ideas with a model of this size, 79" wingspan.
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Old Jan 21, 2013, 03:49 PM
So I'M meant to be in control?
Colonel Blink's Avatar
Ilkley, West Yorkshire, UK
Joined Nov 2008
3,504 Posts
I've thought about building an Invader several times, and each time think that a different way is probably the best.... I've considered pull inwards only (both rudders tensioned by rubber bands to go outwards); single central servo driving straight outward carbon pushrods; seperate submicrominimicrobloodytidgy servos, one for each rudder....

One thing I definitely probably(!) decided upon was to have the thing twin electric; firstly because I think the design looks like a twin with no engines, and secondly having the propwash across the rudders (rather than between them if it were a single nose-mounted motor) would increase rudder (and elevator) authority and would at least partially make up for the fact that the rudders would probably be undersized if you didn't increase fin size.

Oh, and another (desperate!) rudder option I thought of was to add an additional central fin a la Avro Manchester....
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Old Jan 21, 2013, 06:33 PM
Missileer Extraordinaire
Mel Duval's Avatar
Joined Jun 2001
2,046 Posts
Quote:
Originally Posted by Colonel Blink View Post
...........

One thing I definitely probably(!) decided upon was to have the thing twin electric; firstly because I think the design looks like a twin with no engines, and secondly having the propwash across the rudders (rather than between them if it were a single nose-mounted motor) would increase rudder (and elevator) authority and would at least partially make up for the fact that the rudders would probably be undersized if you didn't increase fin size.

.....
A twin would be interesting because you could use differential thrust to boost rudder effectivity....
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Old Jan 21, 2013, 10:04 PM
Registered User
Holland, Michigan
Joined Dec 2006
390 Posts
Twin Rudder Control

I don't know if this will help you with your twin rudder question but I faced this with my Yogi build 1 1/2 years ago. First I tried a mechanical linkage system that was awkward and heavy. Then I decided to rebuild the rudders to using a spring system many DLG pilots use for hand launch.

Each rudder has a little music wire with two simple short bends. These insert into the rudder at one end and into the vertical fin at the other. Both rudders push outboard by the spring pressure until tied to the bellcrank and the bellcrank hooked to the pushrod leading to the servo arm.

Once it was adjusted I have never had to mess with it again. The rudders center perfectly, operate smoothly and so far with no issues. This is a very light weight set up. Because the rudder springs pull against each other there is absolutely no stress on the servo as is the case when using this system with only one rudder.

Try this link and scroll down to report 10 and 11: http://www.rcgroups.com/forums/showthread.php?t=1502779 I think you will find it all explained there along with pictures.

Some vintage RC designs are flown with only a left or right side operating elevator. You will find this method on some 'old timer plans'. I haven't tried this myself but your build is primarily a free flight with enough control desired to set the glide and bring it home.

Looks like a fun project...hope you move forward on it...good luck.

Regards, Larry
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Old Jan 22, 2013, 08:14 AM
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United States, AK, Valdez
Joined Apr 2008
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LWeller, thanks so much for the advise, greatly appreciated!
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Old Jan 22, 2013, 08:36 AM
Registered User
Napa, CA
Joined May 2007
611 Posts
Larry,

I just looked at your Yogi build: Fantastic! Your approach to the twin rudder control really fascinated me; I plan to use it. I'm currently building a 150% Half Pint which is already looking tail heavy, so your method (including the built up rudders) comes in handy. Thank you!
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