Avoiding Crashes — 5 tips to save your RC airplane!

Jun 21, 2013 9 Comments by

We’ve all been here, done that!

The life expectancy of your RC airplane is directly proportional to how well you follow directions. That is to say, you’ve built and setup your plane properly as explained by the instructions. This article is intended to give the first time model builders some helpful tips for being successful the first time out. We’ll talk about avoiding the avoidable, not correcting for things like crosswinds or hitting something with your plane.

There are several things that are common in that they can greatly affect your airplane’s safety. Like a weak link in a length of chain, any one of these things can bring the best built planes down. Let’s break down these areas of concern into the following groups.

  • Center of Gravity Balance Point. In my opinion, more airplanes are damaged or destroyed on their first flight because they were improperly balanced. The balance point for all RC model airplanes (with the exception of small foamy RTF planes,) are called out on the plans of a kit built plane, or in the instructions of an ARF plane. It is absolutely imperative that you take the time to balance your plane properly. Use a balancing jig or simply use your finger tips to hold the plane by the wing to see where it balances. If the tail hangs low while placing your fingers where the instructions say the balance point is, it is tail heavy. If the nose hangs low, it is nose heavy. Of the two, slightly nose heavy is better than slightly tail heavy. As the plane becomes more and more tail heavy, the more and more sensitive it becomes to control inputs until it gets to a point where it is uncontrollable. We’ see this all the time. The plane takes off and the wing rock back and forth. The nose stays high and eventually the plane snaps to one side and crashes. You prevent this by adding nose weight.

  

(Above) The GP Balancer is a great tool to have in your workshop. Du-Bro Stick on weights are excellent for adding nose weight.

    • Engine/Fuel System. The next item most likely to kill your plane is an unreliable engine. This can be caused by a poorly broken in engine, an improperly adjusted carburetor and/or an improperly installed fuel tank. Always follow directions and break in your new 2-stroke or 4-stroke engine before trying to fly. This requires several tanks of fuel and a controlled running of the engine to condition it for proper operation. What you want to do is obtain a reliable idle and a smooth transition from idle to full power. When it comes to power output, always run the engine slightly rich, not lean. Lean engine runs cause overheating and can lead to a damaged engine. The fuel tank should also be installed properly to supply the engine with fuel. Assemble it correctly and install it so the center of the fuel tank is even or slightly below the center of the carburetor. The simplest setup is a 2-line setup with the output line attached to the carburetor and the other line acting as a vent. You fuel the tank by removing the line from the carburetor. A common problem is a fuel clunk that gets jammed forward in the fuel tank after a hard landing or nose over. Always make sure the fuel pickup line is free to move around in the tank. If it is jammed forward, the next time you take off and the model’s nose is pointed up, the fuel level will move back and the clunk will start to suck air and cause your engine to lean out and die.

    (Above) The model airplane engine is an important investment in your hobby. Treat it right and it will treat you and your airplane right.

    • Radio Battery. Another common failure point is the onboard battery powering the receiver. You should always fully change your radio system the night before you go flying and have a battery checker to monitor the condition of your battery pack at the flying field. Batteries seldom fail before you next flight, and when they give up the ghost during a flight, you are out of luck because your model is going to lose control and it will eventually hit the ground…hard! I check the battery voltage before every flight with a loaded volt meter. You simply plug it into the charging jack and it tells you what the voltage levels are. If the voltage is below 4.8v for a 4 cell pack or below 6v for a 5 cell Ni-Cd pack, do not fly! So it is always good to have a DC quick charger/peak detection charger in your field box so you can top off your battery pack. Also, check the battery switch and connections. Never install a battery pack without foam rubber padding. Always make sure your pack is securely installed and doesn’t more around.

    (Above) Use good quality battery packs and use high capacity packs when you use more and more servos in a plane.

    • Final Condition Check Besides these three basic failure points, always check the condition of your model before every flight. Make sure the radio system and servos are properly installed and working correctly. If you have a programmable radio, make sure you have the correct model memory called up for your airplane. Check the screws and clevises and make sure everything is connected and secured properly. If you have recently repaired a plane, or if it is the very first time you’ve brought it to the field, have a friend go over it as well. A second pair of eyes can often detect something you over looked. Always check your control throws for proper amount and proper direction.
    • Don’t push a bad situation! Again, we see this all the time! If your engine is just not operating properly, or if something is not working correctly, just don’t fly! The best course of action is to step back and take a breath. Maybe you need to work on the engine back home on a plane stand, to solve the problem. If an aileron is twitching, maybe the servo needs to be replaced. You are the pilot in command. Abort your flight attempt. The plane you save may be your own!

    Photos courtesy of rcplanescrashes.com

    Featured News, Gerry Yarrish

    About the author

    Senior Technical Editor About Me: I have a lifelong passion for all things scale, and I love to design, build and fly scale RC airplanes. With 20 plus years as part of the Air Age family of magazines, I love producing Model Airplane News and Electric Flight.

    9 Responses to “Avoiding Crashes — 5 tips to save your RC airplane!”

    1. Pete Eason says:

      These are all excellent points, and I hope to never be a victim of them. I my issue in every crash I had is stick freeze/disorientation. Inverted to close to the ground, moved the stick the wrong way…Near an obstacle flying towards me, moved the stick the wrong way….See a pattern :)

    2. Marc Brown says:

      Don’t push a bad situation got me. Had engine issues; Couldn’t get the mixture right and it kept dying when I cut the throttle. I flew anyway and was practicing stall turns. I was able to make a few then it happened; motor died. I was trying to glide back to me and got greedy because I didn’t want to walk in a cow pasture to go get my plane so I tried to make it all the way. She tip stalled at 60 feet and I almost recovered out of the dive. It was a glancing blow with terra firma and fortunately with a little ply, balsa and monocote; was repairable. I was one of the lucky ones… My plane flies again…

      When I was learning to fly my instructor said “Don’t fall in love with it. All planes have an expiration date on them; we just don’t know when it is…”

    3. Alex says:

      thanks for this tips, 30 years loving RC planes, but never learned to fly, now I decided to do that, Im building a Kadet Senior, adn collecting all tips to put it in the air, Im a little afraid!! but definetly has to do this step!!

    4. Trevor says:

      Hello, very good points. From my experience, no gas, and not checking the battery was some fatal causes at my field. I have a Patty Wagstaff Extra 300 that I fly in Arizona at Superstition Airpark, e maiden flight the wing flew off. Caused by vibration from the engine, it vibrated the nut right off. It is amazing how a little thing like a nut would bring a plane of that size down. ALWAYS CHECK THE AIRPLANE BEFORE EACH FLIGHT.

    5. Don Gardner says:

      I liked all your tips, here is one more that I think causes many crashes, it is flying past our attention span, which is about 10 minutes for me. I don’t have any statistics but I do believe that most dumb thumb crashes occur after 10 minutes of flight.

    6. Andy Michels says:

      On one of your comments of balancing I have is my plane is nose heavy could not move radio gear far enough back to balance so I added a little tail weight’ was this the correct way she seems to fly good but seems a little heavy now the model is great plane stick 40 arf with a os 70 4 stroke any thoughts what I could do different or leave it alone Thanks A lot of great stuff on this news letter Andy Michels

    7. john says:

      I lost my pride and joy Venus2, now discontinued. The cause of the crash was a faulty receiver switch. I purchased this Hobbico “heavy duty switch” this spring. I intend to send that back with a nasty grahm… FYI make sure you have complete control while moving the wires around (that come out of the switch)

    8. Richard Zbinden says:

      So I crashed..sad but let’s get the craft put back together, done! Everything is fine with all the controls except the electric motor does not run. Check battery, all controls work (except motor) OK, check the transmitter, all is OK, I have selected the correct model, all switches are on…help!!! How do I find out what is wrong with my motor?

      • Anže Jurkošek says:

        Check your ESC…mine with UBEC has unsoldered resistor ground so when I start fliing and go for dive resistor lose contact with ground and cut my TX off and motor was running for 5 sec, lose signal stoped and chrashed… Thanks for trainers and my knowledge of electronics I have repared and he is alive

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