Well I took my brand new Radian Pro out for it's maiden flight this morning.  I had gone over everything that I could think of and did my checks pre flight.  Had a nice field of alfalfa about 6 inches tall and a gentle breeze, a bit of fog yet but I wasn't planning on getting too carried away on my first flight.

 

Gave it about 3/4 throttle and threw it up and it took off great .... flew about 20 yards in a shallow climb, rolled over to the right and went nose down right into the ground.  Did a fair amount of damage to the front cockpit .... nothing that a little glue and TLC probably can't fix.  Been evaluating trying to figure what went wrong.  Noticed that the screws that hold the wings on had moved .... is it possible that the screws weren't holding , or did it hit that hard?  Left wing aileron arm came unhooked in the crash ... looks like the little ring keeper failed with the impact, it was in place on take off.  I believe that the cause was my C G ... it was not as perfect as I would have liked, it was off about an inch... felt pretty good though.  This is supposedly an easy bird to fly and launch but something wasn't right .... unfortunately I don't know what that something is ... yet.  It did not seem to respond to commands to climb or turn which was puzzling and I gotta admit .... it is hard to watch something like that.  I love that plane and it took me a long time to pull the trigger and buy it cause I am pretty careful with money.  I wish I had someone to take me under his wing and help me evaluate ... feel kind of all alone and not sure what to do next.  HELP?

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If your CG was an inch too far back, that could make and aircraft practically uncontrollable.  An inch too far forward is not nearly as bad.

It seemed tail heavy when I put everything where it was supposed to be so I slid everything forward as far as I could.  Battery was right in the nose along with the speed controller.  But C G was still back about an inch .... maybe that was it then.  Thanks for the input ... I will patch it up and retry as soon as I can and add weight to the nose until all is right.  I am still puzzled by the screws that hold the wing however ... they should not have moved at all.

Again thanks.

If your cg was an inch back, the plane is  not flyable, especially by a beginner. I know you're a beginer because you tried to fly knowing of the CG situation. I will try and find some very helpful links and post them here on your forum.

 

Thanks much appreciated.

One of the biggest factors in successfully (and relatively cheaply) learning how to fly any R/C model is having someone experienced get you off on the right foot and shepherd you through the learning process.  One of the best ways to do this is to hook up with the local model flying club - provided there is one.  While they may not understand or even care what your end goal is, usually at the very least they will bend over backwards to help a newcomer get started, and provide him/her with the foundational skills to get a model off and back on the ground in one piece.  Your mileage may vary, but this has been my experience over the last 40 years.  

If you have a local hobby shop (LHS), they should be able to point you in the right direction.

1" behind stock CG is extremely tail heavy. It is very hard to control the airplane in this configuration if even possible. I have found with my 70+ flights on my Radians that the best CG location is 1/4" behind stock location. This is a little closer to neutral stability but offers hands off, level gliding with the motor off. As a beginner I would fly it at the stock location until you can understand how flying characteristics change as the CG moves forward or aft and use that knowledge to determine what flying characteristics you desire and what it takes to accomplish that. Although the Radian Pro is s glider and relatively easy to fly I would not recommend the pro model for beginners. Look at the stock Radian. For FPV/UAV use, the stock Radian is better than the pro model in pretty much all disciplines. It can carry more weight without altering the flight characteristics than the pro, it can glide longer an lose less altitude that the pro, it's more stable for hands off flying whxh means your autopilot doesn't have to work as hard, and overall the airplane is more simple (rudder elevator throttle) which means when you crash you won't have as much time invested.

Well I have the Pro and about $400 invested so I'm not going to go buy another plane.  The Pro will work fine, I just did not realize the difference an inch can make.  Information is out there but it is not very complete, I have read and researched for weeks before I bought the Radian Pro.  I flew the simulators and became good with them and I am confident that I can fly the plane adequately.  It seems amazing to me that putting all the equipment as far forward in that plane that you are expected to add more weight to balance out the C G.  Seems a little crazy ... but that is how one learns and it seems that I always have to learn my lessons in this manner, so why should flying R C Planes be different. 

 

Thanks for your thoughts everyone and I really do appreciate them.  I have not had the opportunity to try again as my schedule has gotten hectic.  I will be very careful and precise the next outing.  Please by all means send all thoughts and suggestions as I will appreciate them greatly.

 

Thanking all in advance.

Hi there sorry to hear about your crash.

Did the plane pitch hard up before it rolled over. How fast was the plane travelling. I have seen enough planes at our club field with the cg too far back and normally they will pitch up hard. 

It kinda sounds to me like a tip stall or an aileron glitch..... I understand what the other guys are saying but the way you described the take off.

"Gave it about 3/4 throttle and threw it up and it took off great .... flew about 20 yards in a shallow climb, rolled over to the right and went nose down right into the ground"

Doesn't sound to me like CG error. I would go back through your radio have a check... do a range check at half power...

Don't get discouraged....... 

Not experienced enough to take you under my wing but will pass along what I learned fom the best pilot in the St Louis RC Flying Assoc.

Chris is right - cg is critical and I have many crashes to prove it. JH took me in hand and gave me a feel for where to put my fingers under the wings.  From there I learned to do power off hand launches.  For the Easy Star, grip well ahead of the cg/ and launch horizontally, any upward launch and the wing will stall. Typically the 4 planes I have built were tail heavy, and the ship will drop so start from a kneeling position to minimize damage. Add lead weight as far forward as possible and try again. Car Quest sells adhesive backed lead strips about15mm wide and 3mm thick used to balance car wheels. Keep adding weight in small increments until a true ,if short , glide occurs. Then add more weight and launch from a standing position. After several iterations the magic moment came and the Star soared like a bird.  I walked off the distance and made a crude estimate of a glide ratio between 7:1 and 10:1.  It has easily soared in thermals. The manufacturer says set the cg at 78mm back of datum.  The hand launch test was best at 66mm back of datum.  Go figure.  PS The hand launch glides will  also  reveal misalinged surfaces and lateral unbalance probles if any. Good luck  The Star weighs 30oz.  It is not possible to hand launch a 30lb plane if that is what you fly!

 

Mike Cowan

Craig, after reading all the other responses and adding my 2 cents worth I would say that it could not have been your CG, as the other said, it would have been uncontrollable from the start. Check your radio equipment and battery connections, sounds more like a loss of power or a possible interference which could have caused an aileron glitch.

The R Pro is a sailplane so you should have no problem finding the right cg by hand launching. Still, other thoughtful comments express concerns about the attitude at crash. Let's review these items of the crash trajectory as you prepare for flight.

High aspect wings are subject to accelerated tip stall because the angle of attack tends to be higher at the raised tip  even in a mild turn from purely geometrical reasons. The sudden wing drop and roll could be a result of a tip stall due to a slight left yaw disturbance and followed by sideslip/spiral entry.

 

The lack of climb rate with the throttle advanceded indicates that the plane was lugging on the backside of the power curve (too high an angle of attack-which is consistent with a tail heavy cg.) and headed for a stall.

 

With the throttle advanced, and a little left rudder in to compensate for prop effects, the right wing has a slightly higher angle of attack than the left and would be the first one to stall .

 

Don't give up. Make the plane glide smoothly on a power off hand launch by trial and error placement of the cg, and it should it climb out like a champion when you when you "go with throttle up"..

Mike

I agree with what has been said. CG is critical and should NEVER be aft of the mark unless you are a very experienced 3D aerobatic pilot, then you may want it a bit back but otherwise that only gives you difficulties.

What I think may have happened here is that you had the ailerons reversed. The description of the flight fits that error well. The plane starts to lean, you try tocorrect but the ailerons are reversed so the roll increases and ... bang. Most experienced RC flyers have a habit of checking the control surface movement before every (!) take-off, also to check for this setup error, which even experienced builders can make. Always move all surfaces before flight and see if they move freely and in the right direction. Control travel can be reversed by a setting in most transmitters and sometimes (I did this the other day) you forget to select the correct program for the model.

Do I understand correctly that you are a beginner pilot?

Another advice I give all beginners is to acquire an RC simulator and train to your wits end in it. These range from almost free ones like the FMS to expensive masterpieces, which the champions use to hone their skills. They alwasy save you money in the end. Even the simplest ones help you to learn how to fly. One of the first things to work into your spinal reflexes is to fly with ailerons when the plane is headed towards you. When you get that right without having to think, you are a long way towards being a good pilot.

I strongly support the advice to join a local RC club. The lads there usually love to help newcomers. If you don´t find a kindhearted mentor there, that club has problems.

I also want to remind that every beginner gets thouroughly discouraged at one point, you had yours a bit too early.

Keep the steam up, you will enjoy flying.

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