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Rudder Mod for Four Star

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Rudder Mod for Four Star

Old 02-06-2003, 01:39 AM
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hoppy
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Default Rudder Mod for Four Star

What is everyone's thought on modifying a four star 60 rudder only? I'm adding about 30% of surface area to the rudder but nothing else. (no mods on elevator or ailerons)

I know what adding more area to the rudder will do, (I think) but just wanted to make sure I don't need to add the same amount to the elevators.
Old 02-06-2003, 05:43 AM
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WORNBOOTS
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Default Rudder Mod for Four Star

I am curious, why do You want to increase Rudder surface?
And what type of Radio system do You have?
Dan Z
Old 02-06-2003, 12:29 PM
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hoppy
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Default Rudder Mod for Four Star

This is going to be my second 4 *. My first one is stock. I think I really just want to see what the difference is going to be like when trying maneuvers.
Old 02-06-2003, 01:08 PM
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cruzomatic
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Default Rudder Mod for Four Star

I'm thinking a stock 4* should be able to perform most aerobatic maneuvers. Nevertheless, a larger rudder would allow it to make a nicer knife edge and stall turns. Let us know how it turns out if you do decide to go with the mod.
Old 02-06-2003, 01:28 PM
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Geistware
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Default Re: Rudder Mod for Four Star

When you say "RUDDER ONLY" are you going to remove the ailerons? If so, you may need more dihedral

Originally posted by hoppy
What is everyone's thought on modifying a four star 60 rudder only? I'm adding about 30% of surface area to the rudder but nothing else. (no mods on elevator or ailerons)

I know what adding more area to the rudder will do, (I think) but just wanted to make sure I don't need to add the same amount to the elevators.
Old 02-06-2003, 01:28 PM
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hoppy
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Default radio

Wornboots, my radio is a Futaba 6ax or something like that. (6 channel programable).
Old 02-06-2003, 02:11 PM
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hoppy
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Default Rudder Mod for Four Star

Geistware,

What I meant was that I'm only modifying the rudder. I will leave the ailerons and elevator stock.
Old 02-06-2003, 02:38 PM
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DSJBEAN
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Default 4*40

I added an additional 1/2 inch to all control surfaces on the 4*40 I built for myself and a friend of mine. They fly great.
Old 02-06-2003, 02:40 PM
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punkey71
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Default rudder

Hi,

I added about 2" to the back of my 4*60 rudder.

Knife edges better and also easier to hover....I know this plane wasn't designed for that stuff, but it was my first kit and as my flying skill increased I wanted to play around with it.

I figured I'd learn on this one instead of trashing a nice 3D plane while learning how to 3D!

If you do it, add a counter balance and use a higher torque servo (Hitec 545 atleast...605 even better).

Although i've moved on to more aerobatic planes, I haven't had the heart to sell my 4* as I did the others....It's just such a nice plane to relax with or alot of fun with mods and a 91 four stroke.

It can be so docile, I even teach my friends how to fly R/C with it - on low rates of course!

Best,
Harold
Old 02-06-2003, 03:14 PM
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hoppy
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Default Rudder Mod for Four Star

punkey71,

Counter Balance??

Do you mean that adding the additional weight to the tail means I will need to counter that with more weight up front? Or are you referring to something else?


Thanks for the input.
Old 02-06-2003, 04:02 PM
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punkey71
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Default counter balance

A counter balance is when part of the control surface...in this case the rudder it in front of the hinge line.

Look at a 3D plane with the rudder deflected left or right and you'll see the uppermost part the the rudder is both in front and behind the hinge line. This takes some of the work load off the servo.

It's really easy to understand if you can see it...i'm probably not doing a good job of describing it...anyone got a pic?

Harold
Old 02-06-2003, 04:23 PM
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Default Rudder w/ counterbalance

Here's a sketch as I have seen it:
Attached Images  
Old 02-06-2003, 04:44 PM
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hoppy
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Default Rudder Mod for Four Star

I didn't use this method. I just added extra length (1 in. average because it tapers) to the back of the rudder. Do you think I will run into problems? I'm having a hard time understanding how the counter balance helps the servo. The only thing I can think of is that the counter balance takes some of the pressure off the hinges and that helps the servo. Is that true? If so, I really didn't add a whole lot of extra weight so I don't know if it's needed. But hey, that's why I'm asking.
Old 02-06-2003, 04:49 PM
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Default Rudder Mod for Four Star

The counterbalance on the rudder catches the airflow and trys to turn the rudder in the same direction the servo is turning it. The airflow over the rudder fights the servo, the counterbalance aids the servo. With this type of configuration, the servo doesn't need as much torque, or current. Less current means more flying time from your batteries. Less torque means less expensive servos.

In the end, it's up to you.
Old 02-06-2003, 05:41 PM
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hoppy
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Default Rudder Mod for Four Star

Strato911, Thank you for explaining that. It makes sense now. Don't know if I will try to add that piece or not. I can always go back later and do it I suppose.

I've seen that on many plane and thought it was for looks...
Old 02-06-2003, 05:55 PM
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strato911
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Default Rudder Mod for Four Star

Since you haven't increased the surface to much, you could just use a beefier servo, but keep in mind this will increase the load on the batteries, and shorten the available flight time. Do you have a field charger? How much capacity does your pack have?

Some RC planes may have it just to look more like the full scale aircraft, but as far as I know (I'm not an aircraft engineer) full scale use this design on the rudder and elevators to reduce the load on the systems.
Old 02-06-2003, 06:09 PM
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hoppy
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Default Rudder Mod for Four Star

I have a battery checker with load capability. I will be able to monitor the batteries. Thanks.
Old 02-06-2003, 07:32 PM
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Default Rudder Mod for Four Star

hoppy
Some radios allow differant control amounts, and Your question about increasing the elevator surface is why I asked about what radio system.

You have gotten very good responses above, and they seem to answer Your questions, Good Luck and let us know how it goes.
Dan Z
Old 02-06-2003, 10:02 PM
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Roy-RCU
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Default Rudder Mod for Four Star

If you really want to increase performance,
clip one bay off the wing, ie 'clipped wing'.
This will give you better roll rate and will not
affect the slow flying but will increase the
ease of landing. It will take enough of the
floating caracteristic out of it to make it
more stable when landing... just my 2 cents..

Roy in Texas
Old 02-08-2003, 04:34 AM
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Mighty Mouse-RCU
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Default Rudder Mod for Four Star

Have the fun of building airplanes is to make minor changes to the designs and observe the results. It'll fly great. No problems. Wouldn't really worry about the servo. Any standard should do with a 50 size engine. The elevators will not need any extending. They have plenty of control. The added weight shouldn't change your CG very much if you choose your wood carefully. Perhaps moving the engine ahead a bit would offset it some. Good luck and have fun in the "design" stage of building.

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