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Old Dec 11, 2012, 10:04 AM
I Fly!
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United States, AL, Huntsville
Joined Jan 2011
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Or you could shift the battery forward if you have a lot of down elevator trim for level flight
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Old Dec 11, 2012, 10:37 AM
Drifting off the reservation..
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USA, LA, Broussard
Joined Jan 2011
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Originally Posted by Jovanx View Post
Speaking of guns...somewhere in the back of this thread is a bizarre story of a farmer who shot down 3 rc planes and then threw them in a pile and burned them. I stumbled across it when I was doing a search, and it went back to a time before I got my RP. It was the craziest story and it went on for pages...they went to his house and tried to talk him into reimbursing them for the planes, and then one of the pilots challenged him to a contest where it would be gun against plane and the winner takes all. At the last moment the farmer pulled out of the contest because he didn't want to risk losing his favorite gun.

In the end the guy did give them some money and then said he wanted to learn to fly so they taught him and a new pilot was born and everybody lived happily ever after. I don't know if I believe any of it, but it was an entertaining read. A few minutes ago I tried to find it here and on the Radian thread, but I couldn't come up with the right keywords.
I think that was on the other RP thread (the "rave" one). Appropriately on the rave thread because as it went on, it became pretty obvious that it was a "tall tale".
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Old Dec 11, 2012, 10:46 AM
Tossing planes into the snow
Canada, BC, Smithers
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Ahhh yes there it is! Thanks Jumpy. A lot of people did take it seriously, and it generated some interesting discussion about the validity of using guns to protect your property.
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Old Dec 11, 2012, 12:39 PM
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NorCal
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I have a 'beater' that I paid a grand total of $30 for( with TX) that I fly daily. When I go to the desert after Xmas I intend to set it up on a nice glide and take it out with a shotgun.
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Old Dec 11, 2012, 02:37 PM
Tossing planes into the snow
Canada, BC, Smithers
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Originally Posted by jrtubb View Post
Or you could shift the battery forward if you have a lot of down elevator trim for level flight
That will work to eliminate the elevator trim, but it would also put it back into the same mode as it was when it came out of the box, (and that is not necessarily a bad thing). Many of us are experimenting with pushing the CG aft of the manufacturers suggestion, right up to the neutral point. When you do that, the elevator becomes super-sensitive and even minor lift causes a visible pitch change.

It also seems as though the plane sinks more slowly and stays up there longer, but that might just be an illusion. It is difficult to quantify such things. I am comfortable with flying at the neutral point, and my next experiment is to start moving the CG forward again and see what happens.
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Old Dec 11, 2012, 06:10 PM
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Originally Posted by cliffkot View Post
Finding the optimal decalage angle for your desired CG is easy if you do it empirically. If you want to adjust your decalage to zero out trim for your favored CG location:

First adjust your CG to your liking. Once you think you have it, test this setting on windless days (!!!) and make sure you test at least a half a dozen or so flights to confirm the setting.

When you are sure of your CG location, fly the plane and adjust the trim for the desired cruising speed. Land without touching anything.

Carefully measure the elevator angle in degrees. Then calculate how much you have to alter the stab angle to achieve about 1/3 of that angle on the whole stab. Do the decalage mod, moving the stab to that new position.

I have flown Radians with and without the mod. It is a purest sort of thing. Yes the plane flies a little faster with the mod, but all the decalage mod does is eliminate trim drag. That is really important in competition or if you are flying one of those $1000 dollar carbon birds. Of course most of those have full flying stabs so it wouldn't matter anyway.

What is really important is getting that CG back. Focus on that first. Then look at the new trim required. Maybe you will decide you can live with it.

Cliff
A lot of words have been written about the decalage mod and there is a separate topic devoted to it:

http://www.rcgroups.com/forums/showt...646181&page=99

Everyone has there own methods and opinions but I disagree with much of what cliffkot has posted about the procedure. I think that Paul Naton's instructions which are posted in the following link are easier.

http://glidefast.typepad.com/glidefa...-ups.html#more

My only caviet is to measure the factory decalage angle before you start. Not all Radians are identical as they come out of the box and you might find that you need to adjust your cutting measurements accordingly. In my case the angle was less than on Paul's example, so the angle adjustment was smaller. Be careful not to go too far because a negative decalage can make the plane unstable.

I am totally happy with my modified Radian. Mine seems to glide slower, not faster, and has a lower sink rate, but it is not necessarily right for everyone. It makes the plane more sensitive in pitch which is an advantage when seeking thermals but also reduces the stall margin. If you are new to the Radian fly it for a while in stock configuration and then proceed with caution if you decide to go for it.
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Old Dec 11, 2012, 07:23 PM
Tossing planes into the snow
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Originally Posted by kaptondave View Post
My only caviet is to measure the factory decalage angle before you start.
What method do you use to measure the angle on a Radian Pro, given the built-in washout of the wings? Do you compare the stab to the wing root, midpoint, or tips?
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Old Dec 11, 2012, 07:50 PM
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Originally Posted by Jovanx View Post
What method do you use to measure the angle on a Radian Pro, given the built-in washout of the wings? Do you compare the stab to the wing root, midpoint, or tips?
I have a RE Radian, not the Pro, but the principles are the same. I measure the incidence angle of the wing adjacent to the root using a DIY gage.
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Old Dec 11, 2012, 09:23 PM
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United States, WI, Appleton
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Quote:
Originally Posted by kaptondave View Post
A lot of words have been written about the decalage mod and there is a separate topic devoted to it:

http://www.rcgroups.com/forums/showt...646181&page=99

Everyone has there own methods and opinions but I disagree with much of what cliffkot has posted about the procedure. I think that Paul Naton's instructions which are posted in the following link are easier.

http://glidefast.typepad.com/glidefa...-ups.html#more

My only caviet is to measure the factory decalage angle before you start. Not all Radians are identical as they come out of the box and you might find that you need to adjust your cutting measurements accordingly. In my case the angle was less than on Paul's example, so the angle adjustment was smaller. Be careful not to go too far because a negative decalage can make the plane unstable.

I am totally happy with my modified Radian. Mine seems to glide slower, not faster, and has a lower sink rate, but it is not necessarily right for everyone. It makes the plane more sensitive in pitch which is an advantage when seeking thermals but also reduces the stall margin. If you are new to the Radian fly it for a while in stock configuration and then proceed with caution if you decide to go for it.
Good advise, from my experience. My Rp had half the decalage angle than the Naton video. Good thing I measured before I flew!!!!!

Re: glide. Interesting, mine seemed to glide at about the same speed, but it definitely signals lift better. I agree that stall margin is less. Regarding the sink rate, I can't say if in purely neutral conditions the mod has helped, but I can detect lift MUCH better. Overall, it's a definite plus, of course, it isn't as easy to fly as when I first got it.

Re: stock configuration. Great advice! I've played with a lot of different configs., but the reason I was confident to play with it is that the stock config is amazingly good (for such an inexpensive airplane.) If/when you start making mods, go slow, and don't let your ego determine your configuration. (I've probably tried three config's for each one that actually made it a better airplane.)

The fun thing is, I've embarrassed a couple of folks with much more expensive sailplanes (and it ain't my ability that did it!). Bottom line, have fun, and grin when they start asking questions!

Jim
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Old Dec 12, 2012, 09:15 AM
RCHN #150
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Lawrenceville, GA
Joined Nov 2007
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I measured wrong, cut the airplane, and ended up with an aircraft that flew better inverted than upright. IMO, for two cents, if you enjoy modifications and have the time and money for replacement parts when you do it wrong, enjoy. I suggest that if you are really that serious about having a performance sailplane, buy one. The Mystique will do everything you could ask.

Rick
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Old Dec 12, 2012, 10:30 AM
Tossing planes into the snow
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Originally Posted by Rickn816 View Post
I measured wrong, cut the airplane, and ended up with an aircraft that flew better inverted than upright.
Ouch. It makes sense, though, that is what would happen if you went too far. Can you tell us what your measuring method was, just to save somebody else from repeating the same mistake? The Mystique does look like a nice plane, but I'm not yet ready to spend 370 bucks on an ARF.

My guess is that if you took the chord line at the root of the RP wing, and changed the stab to that same angle, it would do just what yours does.
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Old Dec 12, 2012, 12:13 PM
RCHN #150
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Lawrenceville, GA
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I laid a straight edge along the bottom of the wing, adjusted for chord thickness. Did not work. I bought a new fuse, kept it stock, and it flies great.

Rick
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Old Dec 12, 2012, 12:28 PM
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Old Dec 12, 2012, 12:54 PM
Tossing planes into the snow
Canada, BC, Smithers
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Originally Posted by Rickn816 View Post
I laid a straight edge along the bottom of the wing, adjusted for chord thickness. Did not work. I bought a new fuse, kept it stock, and it flies great.

Rick
I'm also using the stock decalage and it flies great. The method you describe should work with a standard Radian, but would not work with a RP because the washout needs to be taken into account. If I was ever to do the mod on the Radian Pro, I would probably use the method suggested by cliffkot.
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Old Dec 12, 2012, 01:36 PM
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United States, FL, Port St Lucie
Joined Jan 2011
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Well my RP went down today. Dumb thumbs incident. It was fairly windy but not bad, 10-15mph. Didn't notice any gusts. After my climb out though the wind kept taking it farther and farther out. I was having trouble getting it turned back around, so I flipped the throttle cut switch. My throttle was set at 50%. That wasn't enough to fight its way out of a wet paper bag it seemed so I bumped it up to 75%, it started to turn around, I gave it too much aileron I guess, and the wind just rolled it the rest of the way over. At that point it stalled and took a nose dive right into the wooded area across the field. The wind wasn't blowing E/W today like it usually it was S/N so it was coming right at my back, straight across the field towards the wooded area.

I've never had to walk across that field so I didn't know there was a canal on the other side between me and the wooded area. So I had to go to my car, drive around and take a 1/2 mile walk down to I could see where I was standing on the other side of the canal. I hunted around in the tall shrub and trees for about an hour and it never showed up. I almost called it good as gone and went back to work, but It finally occurred to me I needed my TX with me to try to activate the motor or control surfaces so I might hear something. So that was another 1/2 mile to the car and back out.

After 15 minutes or so walking around and blipping the motor I heard it. It ended up coming down into a gigantic fern bush right in the middle and couldn't be seen from the outside. After countless splinters and thorns I got to it and managed to get myself and the RP back to my car. I expected a lot more damaged from the altitude it fell from but it only broke one wing out of the slot, I still have the piece that broke off for that. The leading edges were damaged and the chunk missing I couldn't find. I was getting pricked and poked too much by thorns and sharp fern leaves to dig around any more. I was just ecstatic I found the plane. The fuse is basically perfect except for a couple dents, but its good. Anyone know how I can fix the bad part of the leading edge?





This sucks, I barely had any flights on this plane and this happens.... Oh well I guess I will fix it just as I did my T-28 a few times. Turns out the T-28 is much more predictable in the wind. I was hoping it would be the other way around....
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