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Old 01-02-2013, 07:13 PM   #1
tscheffel
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Question Parkzone Radian RTF CG way out of whack

Hello all. I took Santa's Parkzone Radian RTF out for the first time and both brief flights ended with intimate meetups with trees (I had to buy a 20' extension pole and squeegee attachment to get it down after the second crash--fortunately there was only minor damage).

The culprit seems to be a CG that appears to be way out of whack (nose heavy, causing it to want to loop, which it did). Afterwards, I finally put together Santa's CG stand and it confirmed my suspicion: nose heavy. My question is: why would a stock RTF's CG be so out of whack? I'm pretty sure I followed the instructions well, even shoving the battery back as far as possible between the two flights, hoping that would move the CG forward (which is suppose to be 63mm back). I even tossed it in the back yard a few times to check the glide path--it looked good (albeit without the lipo battery installed).

Granted, this is my first RC plane but I can follow simple instructions as well as the next guy. And, I've put in a dozen or so hours on the Easy Flight DEMO simulator and have been researching this plane for a year before finally purchasing it.

Thanks for any info,

Troy

p.s. I love the Radian. I can tell it is easy to fly, I just need to fix the CG. I'm just wondering why a stock one would be so off kilter.
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Old 01-02-2013, 07:21 PM   #2
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First off, where is your cg now, and why do you think its too nose heavy? Got a video by chance?

Generally, you want just a touch nose heavy, where does it ballance out?
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Old 01-02-2013, 07:26 PM   #3
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I'm not wanting to appear condescending but far and away the most likely cause of loss of control for someone flying an RC model for the first time is 'pilot error' caused by inexperience. You would be hard pushed to find anyone who has ever tried to fly an RC model on their own, unassisted, who has not lost control and crashed, so it's certainly not just you.
Sure the model may not be properly trimmed out, that's quite normal for a maiden flight and that's why they put 'trims' on transmitters. An experienced flier would almost certainly be able to deal with it without any issues at all.

Best advise would be to go find a club in your area or at least an experienced flying buddy to help you set the plane up and to get you over the first few flights.

As for getting the CG right; are you using the recommended battery?.. How many mm back was your CG position? Within reason a CG that is forward of the recommended spot (i.e. nose heavy) should not cause any serious issues. On it's own that it wont make the plane loop.
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Old 01-02-2013, 07:46 PM   #4
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The CG recommended in the manual is an excellent start point for the Radian so I suspect something else is going on here.

Sadly - I think JetPlaneFlyer is correct - when you are new it is sometimes hard to tell what the issue is, but as a general rule on first flights with no training help it is commonly pilot error.

For example - Tail heavy (not nose heavy) is what causes airplanes to want to loop. And tail heavy is very bad.

Mike
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Old 01-02-2013, 08:42 PM   #5
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@hayofstacks: the CG stand shows the CG to be at the 2"/50mm mark, not 2.5"/63mm where it should be per the instructions/forums. Granted, I should have taken the time to construct the CG stand and check the plane beforehand but since it glided so well when hand-launched (without the lipo) and it's an RTF beginner glider, I took a gamble. Sorry, no video (though I want a vid camera soon for the plane, plus telemetry).

@JetPlaneFlyer: I hear you and concur. I plan to join a local club soon and will ask for advice when I attend their indoor flying session this weekend. I am using the stock LIPO battery (3S 1300mAh).

I'm thinking the forward CG is causing the looping due to my reading various forums about the plane (and the Beginner's Guide to Flying RC aiplanes ebook). I read that when nose heavy, the Radian dives a bit, picks up speed, and the Radian's natural tendency is to nose up/loop. I remembered the suggested advice was to give down elevator during the up-swing to counter-act the behavior, which I did with some success. Under heavy elevator use, it flew the path I expected, even doing figure-8's reasonably well. At that point I should have brought it in for a quick landing but I attempted to fly it long enough to trim it. Unfortunately, I mistimed the elevator use on the last pass and it flew (unpowered) into a large loop, neatly landing in a 50' tree.

If I went out now and flew it I'd tape a quarter on the tail and check the CG. I'm looking forward to getting this baby back in the air after fixing the CG.

Bottom line: I concur that I have much to learn and it's best to learn from an experienced hand but I'm confidant that I can correct the CG and successfully fly it solo before I'm able to hook up with my local club. I'm just wondering what I would have done to royally screw up an RTF glider's CG (assuming the CG is indeed my primary problem).
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Old 01-02-2013, 08:56 PM   #6
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I have, on two occasions, gotten Parkzone RTF planes with odd CGs. One was a nose-heavy Stryker the other was ... a nose-heave Radian.

It is a total mystery to me how/why this could have happened, especially on the Stryker, but it did.

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Old 01-02-2013, 08:59 PM   #7
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Welcome to WF, Tscheffel!

Where to start? Well, you want to check the CG of your plane just like it will fly, so always check with the battery installed. In fact, shifting the battery location within the plane is almost universally how the CG of the plane is adjusted.

Next, if you really want to fly planes, I'd recommend learning how planes fly. I'm an aviation geek, so it always eats me up how many people want to fly, but won't bother learning about the 4 forces of flight and how they work together in various conditions to make a plane do what it does. Here's a good place to start learning:

Aerodynamics in flight

Some of it gets a little technical, but just get the basics on the 4 forces of flight, then scroll way down to 'Aerodynamic forces in flight maneuvers'. This will help you understand what you said about the forward CG is not entirely correct.

And make sure your flight controls are working in the proper direction. Seems stupid, but I've seen a guy with a Radian try to hand launch 3 times, every time it looked good for a second, then took a sharp nosedive straight in. Finally broke the 3rd time, and when he brought it back in, we checked and found somehow between his last flight and those nosedives, he somehow reversed his elevator control! No idea what he was doing to do that. I always do a full flight control check before each takeoff.
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Old 01-02-2013, 09:51 PM   #8
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It's strange how a RTF with all the stock components could end up so badly nose heavy (1/2" out), but as I don't have a Radian and and don't know anyone who has one then I cant comment on if that's normal or not. For sure getting it to balance on the recommended spot is good practice, and if that takes some tail weight then reluctantly that's what you need to do.

A nose heavy Cg can lead to the plane rearing up under power but it's not directly the nose heaviness that causes it, it's the up elevator that you have to add to counteract the nose heaviness.

If I'm reading you correctly the plane was trying to pitch nose up, all the time, if this was occurring even on medium throttle then it point to the plane simply being out of trim and needing the elevator trimmed down, rather than a direct result of the CG. In fact correcting the CG could make out of trim elevator worse, not better. Without seeing exactly what was going on it's hard to be sure.

Steve
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Old 01-02-2013, 10:25 PM   #9
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Now the 63mm from the leading edge of the wing at the root is a decent starting point but even that is too far forward for optimized flight. I'd put it there to learn the habits of the plane, anyway, because the plane is very directionally stable at 63mm.

Be aware that the nose on the Radian will rise markedly with throttle application. If you're trying to launch full throttle you're a dead man, headed for the dreaded Radian "death loop." You can launch at full throttle, but you better be ready for what the plane does.

Start out by launching at 2/3 throttle and be prepared to ease in some down elevator to keep the climb angle constant. It will climb at 60 to 75 with no problem, these Radians climb like a pole cat. The more throttle you use the more down elevator you have to feed it to keep a constant climb angle and prevent the <play the music> "Loop of.........Death."

Once you're far enough off the ground, if you get hit by a gust and are turned over on your back, don't panic. Just cut the power, feed in a little up elevator to complete the loop. When you come up on the front side of the loop, feed in throttle and down elevator to stabilize your climb angle and resume your launch.

The motor on a Radian is a launch device not something to power the plane around on. She's a sailplane, not an airplane. She will never be happy cruising around under power. She will astound you with her soaring capability.

Enjoy! The Radian is a special plane with a goodly dose of magic applied.
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Old 01-03-2013, 02:36 AM   #10
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@mclarkson: yeah, not sure why a stock plane would be so out of whack, especially with the battery as far back as I can force it. Maybe my 6 y/o son jammed some Lego Star Wars figures into the nose section without my noticing.

@xmech2k: Thanks for the link. I took a Private Pilot Ground School course in college many years ago (and spent 20 years in the Air Force but not as a pilot) so your link provided good refresher training.

@JetPlaneFlyer/Rockin Robbins: I was able to easily hand-launch the Radian at about a 35 degree angle at 60% power. It climbed quickly. Once I cut the throttle, it pitched forward, picked up speed quickly, then nosed up and looped (which I've read is the Radian's tendency). It was essentially continually porpoising until I figured out how to give it extra elevator at the right times to counter-act its natural desire. I wish I could have that last loop back though.

I will fix the CG and give it another whirl this weekend. I'm also going to apply transparent duct tape to the leading edges and spray paint the bottom of the wing. Once I'm a competent flyer, I plan on getting a DX6i and link it to the DX5e so I can teach my 3 kids how to fly. I also want a video camera and a Spektrum STi telemetry module. Now if only I can figure out how to get my Raspberry Pi in on the action!
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Old 01-03-2013, 02:53 AM   #11
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Originally Posted by tscheffel View Post
@mclarkson: yeah, not sure why a stock plane would be so out of whack, especially with the battery as far back as I can force it. Maybe my 6 y/o son jammed some Lego Star Wars figures into the nose section without my noticing.

@xmech2k: Thanks for the link. I took a Private Pilot Ground School course in college many years ago (and spent 20 years in the Air Force but not as a pilot) so your link provided good refresher training.

@JetPlaneFlyer/Rockin Robbins: I was able to easily hand-launch the Radian at about a 35 degree angle at 60% power. It climbed quickly. Once I cut the throttle, it pitched forward, picked up speed quickly, then nosed up and looped (which I've read is the Radian's tendency). It was essentially continually porpoising until I figured out how to give it extra elevator at the right times to counter-act its natural desire. I wish I could have that last loop back though.

I will fix the CG and give it another whirl this weekend. I'm also going to apply transparent duct tape to the leading edges and spray paint the bottom of the wing. Once I'm a competent flyer, I plan on getting a DX6i and link it to the DX5e so I can teach my 3 kids how to fly. I also want a video camera and a Spektrum STi telemetry module. Now if only I can figure out how to get my Raspberry Pi in on the action!
Sounds like a great plan! I am kinda wondering about the CG myself. It shouldn't have a nice glide without the battery unless the batt sits at the CG. It should be porpoising more than...well...the mammals at Seaworld. What do the tail feathers look like at neutral stick? Maybe some incidence issues? Do the tail and wing appear to sit at the same angle of attack? I know it's a lot of questions but a sailplane shouldn't need that much correction or stick input. Usually once trimmed, they are pretty much hands off until you need to turn them. Pictures might help us diagnose you better, if possible. Just keep in mind we're trying to help, that's all.

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Old 01-03-2013, 03:16 AM   #12
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I agree with Gary. Incidence issue or too much up in the elevator at neutral stick.
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Old 01-03-2013, 03:21 AM   #13
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Originally Posted by tscheffel View Post
@JetPlaneFlyer/Rockin Robbins: I was able to easily hand-launch the Radian at about a 35 degree angle at 60% power. It climbed quickly. Once I cut the throttle, it pitched forward, picked up speed quickly, then nosed up and looped (which I've read is the Radian's tendency). It was essentially continually porpoising until I figured out how to give it extra elevator at the right times to counter-act its natural desire. I wish I could have that last loop back though.
You've read that's the Radian's tendency? I've never heard, read, experienced or imagined any such thing. When you cut throttle and push to level the plane sits there like it was glued to the sky! It does not pitch down, it does not pick up speed, it SURELY doesn't loop.

You have serious problems. Check your elevator position at neutral stick position. It should be level with the stab or even slightly down. Your CG should be 63mm aft of the leading edge of the wing at the root. If those two things are true, then the Radian will not pitch down, pick up speed or loop when you cut the power.

The entire issue with looping Radians is newbies taking off with too much power and not expecting the pitch-up characteristic of the plane under power. That's IT. Radians don't TEND to do anything like what you're describing. It would be difficult to FORCE one do that.

I think we're missing some information. How about some video?
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Old 01-03-2013, 04:11 AM   #14
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Sounded like a stall to me, for how it was being described.

And if your 50mm from the trailing edge, your tail heavy, or nose light...

Hardest thing with any plane is figuring out where it likes to stall, and getting used to its bad tendencies.

I give myself a 50% crash/land ratio with any plane I have not flown before, setup correctly or not.
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Old 01-03-2013, 04:15 AM   #15
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Disreguard that... ment to say nsoe heavy, brain fart.
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Old 01-03-2013, 12:51 PM   #16
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Originally Posted by hayofstacks View Post
Sounded like a stall to me, for how it was being described.
Now THAT's not a brain fart. I think it's what happened but we have to figure out why.

As far as pilot error goes, the "stall" (which is no stall at all with the CG at 63mm or less, the elevator is just running out of authority) could happen like this. At the top of the climb, if you dont come out of the throttle gently while feeding in some down elevator to level the plane (that's "push to level") then when the throttle is pulled back the plane is still in a climb attitude. It surely cannot fly long in that attitude, it runs out of kinetic energy.

Being a nose heavy plane it will not stall the wing, but the nose will fall as the elevator loses authority to lift the nose. At that point the plane is a buffalo turd. The nose is going to point to the ground and the plane will fall until it is traveling fast enough for the elevator to lift that nose again.

The puzzling part is why a loop should follow this. Possibly tscheffel is feeding in full up while the nose is falling, trying to control the plane while it has no control. When the elevator DOES regain authority, he's commanded a loop which has nothing to do with something wrong with the plane.

One thing for sure. With anything less than A LOT of up elevator, the Radian can't loop after a stall. Porpoise, yes, loop no. It can't have much up elevator at neutral position or he'd loop in the launch phase. Therefore the up elevator (and the loop) has to be coming from the pilot.

That's how I see it but it's just conjecture. Educated conjecture, but easily disproved by facts

tscheffel, you seem to know what to do here. I'm sure you'll come up with the solution yourself. You should have read some of OUR experiences when we first flew a Radian!
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Old 01-03-2013, 02:58 PM   #17
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Thanks for the continued feedback and suggestions. I appreciate all the knowledge sharing.

As some have already said it's entirely possible the crash is completely due to pilot error and not the .5" CG issue. I'm not yet convinced of that but it's a definite possibility. When I cut the throttle and let go of the elevator stick, the plane would quickly tip over and dive and eventually loop (or porpoise, depending on speed). Also, it glides beautifully when hand-launched and powered off which led me to believe the elevator trim is within normal limits. This led me to believe it is largely a CG issue. Perhaps not. In any case, I will fix the CG (to the recommended 63mm) and fly it again on Saturday and will post the results of flight test #3 (it should be 20 degrees warmer out--yea!).
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Old 01-03-2013, 04:07 PM   #18
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Absolutely pilot error. It is common to "over power" gliders for climb. The Radian is powered that way. It will climb like crazy under power and even loop. I watched a semi-experienced pilot drive one into the ground that way not expecting a lazy flying glider to do that.

The CG and trim are designed for OFF POWER GLIDE! If you trim it for power it will glide like crap. It's not a sports flyer, it's a glider.

There are some tricks you can do with combining down elevator + throttle to flatten the climb with a better TX, but not with the DX5e. Some people will also modify the down thrust but that's kind of advanced building for a newbie looking for an RTF.

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Old 01-03-2013, 04:34 PM   #19
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@flydiver: So are you saying I shouldn't worry about the CG being off .5"/13mm and instead re-fly the plane as-is? I would think that would be inadvisable but I have no experience to base that opinion on (other than 2 flight tests that didn't end well). My rookie noggin tells me to get the CG to what the manual says (2.5"/63mm) and try again. If the CG is correct and my plane ends up in a tree again then it's all on me, which I can live with. I just don't want to be fighting a CG issue at the same time I'm fighting rookie mistakes.
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Old 01-03-2013, 04:39 PM   #20
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A little bit of aerodynamic theory to pass the time.

Your plane has an aerodynamic center, the center of pressure for all the surfaces of the plane in the pitch axis in this case. And it has a center of gravity. In the pitch axis this aerodynamic center is called the center of lift or CL. Center of gravity is designated CG (NOT COG! I don't know where that came from but we must kill it before it multiplies any further.).

Okay, for a stable system, that is, a plane that tends to self correct in the correct direction, the CL must be behind the CG. It's easy to visualize if you think about an arrow. The fins move the aerodynamic center of the arrow behind the center of gravity! The further behind the center of gravity is ahead of the aerodynamic center, the straighter that arrow will fly.

Your airplane works the same way. The distance from the aerodynamic center to the center of gravity determines some important characteristics of how your plane flies. Just like the arrow you want the CL to be behind the CG. That makes the plane tend to self-correct and straighten itself out if it gets out of line. Imagine if a buffet of wind were to knock your plane into a dive and you had negative instead of positive stability. The tail wouldn't correct the plane to fly straight, the plane would actually want to swap ends and fly backwards. That wouldn't work for very long........

BUT, we're not talking about an arrow here because your plane has lift. And you're lifting that plane by the center of lift, NOT the center of gravity. Imagine if the CL were an inch behind the CG. Lift the plane with two fingers an inch behind the CG. See how the nose points down? You can measure the weight of the nose. That is the amount of force your elevator would have to produce to hold the nose up for level flight. It's quite a bit of force at that spacing between the two balance points. It's going to take a lot of up elevator, AND it will take some airspeed to generate that force.

So what happens when you slow such an airplane down? First, at speed the thing feels great. It flies like it's on rails. It likes the wind. It's rock steady when you're flying fast. Lots of powered plane fliers have their planes trimmed like this and think it's the way to go. Your Radian will tell you the truth. An overly stable plane is a crater waiting to happen.

So you're at minimum flying speed. Your elevator is angled up to lever that heavy nose to get the plane to fly level. But then you slow down too far. No matter how much up elevator you have, it can't generate enough force to hold the nose up. Your plane dives and you have no control. You say "I just stalled." You are wrong. The wing never quit flying, your elevator just ran out of authority to lift that heavy nose.

You're in a dive, imitating a buffalo turd with just as much control: little or none. You may have some rudder control, but you're in an uncontrolled dive until you're flying fast enough for your elevator go gain enough power to lift your nose to level. Can you visualize that?

So conclusions:
  • The further forward your center of gravity is from your CL. The more altitude you will lose in an uncontrollable dive until you can again fly your plane. If it takes 20' to gain that speed and you dive it from an altitude of 15', a large and heavy planet will get in your flight path. The planet/plane encounter will be entirely harmless for the planet, which will win every time.
  • With the CG too far forward, you can never stall your wing in slow, straight ahead flight. The plane dives well before actual minimum flying speed.
  • When you move your CG back, two things happen. First, your plane will fly much slower and retain amazing control, your sink rate will be lessened remarkably. When you stall, you'll encounter some buffeting (caused by separation of the air flow from the airfoil, the very definition of a true stall), the plane will merely stop flying and kind of flutter forward and down but not in a dive or much of a dive. You still have elevator authority. Blip in a quarter second of down and the plane regains speed and starts flying again. Stalling is now a non-event!
  • BUT as that CG gets closer to the CL your plane loses inherent stability. It does not straighten itself out automatically. You use your eyes and input what the plane needs. Turns will especially feel shaky if you go too far with moving that CG back.
So at 63mm the plane will feel solid. It will track really well. It will dive about 10 to 15' in a dive if you "stall" it. (which is not a stall at all as explained above). It's a great position to learn the plane and get to feel natural flying it. As a sailplane, it has a long way to go and so do you.


Once you are feeling comfortable with the plane and can unconsciously fly the plane without thinking about what control input you need all the time, then it's time to optimize. Remember the gains you're looking for. They're worth it.


Be cautious! Move the CG back to 65mm and fly that for awhile. Then move it back another 2 mm. I found that 70mm was my sweet spot, where I still felt pretty comfortable flying the plane, but suddenly the Radian was entirely transformed! The sink rate was half of what it was. I could slow down to about half of the former minimum flying speed without stalling. The plane came off the launch, I ratcheted back the throttle and pushed the stick forward to level and the plane just......stopped! And refused to come down! It was a true "come to Jesus" moment, I'll tell you!


Different people run with CGs at different spots. This is because some people are just better pilots. Aeajr runs a CG well behind mine. Why? He's a much better pilot who flies much more than I do. His eyes are calibrated to see what the plane needs and his hands are experienced in providing just that. It's not a competition either. Your correct CG is yours and is not better or worse than mine. And yours will change as your skills change. What you call "uncontrollable" today will be "responsive" tomorrow. Take it slow. If you find yourself sweating in terror instead of having fun, remember why you're doing this and move the CG back to the fun position.


Talk about a post that's too long! Some moderator, whack me!
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Old 01-03-2013, 04:47 PM   #21
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The stock CG is fine if you are using the stock battery in the stock position. In reality you can go a tad behind that but I would NOT advise it for a newbie as it actually makes it MORE sensitive (read the fine explanation above until you get it).

I understand messing up and putting in a tree, I've been there. But this plane has been thoroughly wrung out a LONG time ago by Horizon. Set up correctly out of the box it flies quite well. You put it in a tree, that's your fault. Newbies shouldn't fly around trees....period. Search on getting planes out of trees for some amusement.

It IS overpowered, AND you have to learn to fly it that way. Go VERY GENTLY on the throttle. Trim for GLIDE, NOT for power. Then learn to live with the power problem.
Give yourself LOTS and LOTS of space. gliders need it even more than most planes. This plane requires it. For a newbie, about 5x the space you think you need. 4 football fields with no trees is probably barely adequate to start.

The power and the fragility is why I do not recommend this plane as a trainer. It can be a trainer but it has some common glider quirks that throw people plus it doesn't take to crashing as well as some more sturdy planes.

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If you're going to learn to fly them, you have to learn to fix them.
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Old 01-03-2013, 05:17 PM   #22
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@Rockin Robbins: thanks for the very informative post. I especially like your conclusion points. The info makes sense. I've read many Radian posts about moving the CG back to 3.5" (from the stock 2.5") once you're a competent pilot. Your post sheds light on why that would be beneficial. The info also yields the following question.

Question: how will the Radian (or most other sailplanes) behave differently when quickly throttling down versus slowly throttling down?
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Old 01-03-2013, 05:29 PM   #23
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It depends on angle of attack and airspeed/thrust.

I personally have nott flown a radian, but had a buddy that brought one to the park with us when we were slowsticking.

A high lift wing with cause the nose to pitch up under throttle, and airspeed, natrually.

You probably never want to take an airplane, especially a new plane with a un experianced piolit, at 30 degrees verticle, or more. I believe this is why you crashed. Instead of lowering your elevator, I think you were lowing throttle. Which, is more manageable in a flight sim, then real life. It would also cause a tail heavy airplane to dive, and if you applied throttle and elevator under stall (wich should be your natrual reaction), the plane would have full up elevator and lots of airspeed imediately after gaining lift again. You should practice on keeping the plane level and in control, making it fly scale, as you get used to the controls and how the plane flies.

Btw, I would call that a sucessfuly first flight... it was several weeks and many attempts before I got my first plane off the ground cleanly.
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Old 01-03-2013, 05:58 PM   #24
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Hmmm, I was thinking 30 degrees (from horizontal) to be a good, safe angle for take-off for a hand-launched sailplane. I tried to mimic what I've seen in the Radian "Unboxing and Maiden Flight" type of YouTube videos. In any case, the climb was the easy part.

In hindsight, I'm wondering if I should fly with some throttle (~40%?) once at altitude for the first few minutes so I can get a good feel for the plane as well as the transmitter inputs. Then, climb a little higher and slowly power off and see how she does. I'll be getting the CG set to specs first.

I'm anxious to get back out there and give it another whirl. Hopefully the weekend brings good flying weather.
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Old 01-03-2013, 06:39 PM   #25
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Change tail heavy to nose heavy... dunno why I was having such a hard tim with that...

Take off and landings are no different from regular flying, you will litterally just fly it into the ground. Its a good idea to use a fair bit of throttle on take off, but with throttle comes speed. and while your learning the plne at least, i'd leave the throttle at about 50%, if that is where the plane flies pretty well.

Right now what's important is stick time, and orientation. Get it a good 3-5 mistakes high, meaning you can recover 3-5 times before it hits the ground, fly it in a nice easy controlled circle. Once you feel comfortable with one direction, try it in another. Once you get that direction down, try a figure 8. When your comfortable with that, then you can play with altitude and rolls a bit more.

It takes time, and sometimes patiance.

Also, a nost heavy airplane will always pitch down in a stall... I ballance my slow stick out by gaining a bunch of alltitude, chop the throttle, then I put full up elevator into it. When its ballanced correctly, then prop doesn't even spin due to airspeed. If your too tail or nose heavy, it wil pourpose up and down.

You need to become natrual with the airplane and controls. Its the thinking that leads to crashes, so you need to get to the point that you "know" your plane.

The reason behind having a nose heavy airplane when beginning, is to keep the nose down in a stall. That way when you run out of air speed, the plane will natrually dip the nose, rather then falling backwards.

Every nitro guy I've seen setup an electric also set it up very nose heavy, due to fuel consumbtion. On a nitro, you can losr 6-8oz on a .40 plane over the course of a flight. Making the plane really nose heavy on takeoff. As long as your in the front 1/3rd of the airfoil, you ought to be fine to fly.
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