Tips Bench Tuesday - Hand Launching Best Practices
Hand launching and the thought of doing it by yourself especially, have often brought up thoughts of carnage and despair in many people's minds. But taking a model and throwing it into the air is a lot less daunting than people think and in this blog post and the video below we explain not only how, but why.
Well actually the "why" is pretty easy to answer, simply put it's because it's necessary with models with no landing gear. Like many of the newer releases from Hobbyking such as the H-King Reno Aces Series, or the 50mm EDFs to the more established favorites like the Durafly EFX racer, they are all designed without landing gear and for hand launching exclusively. Often these models are sub 1meter wing span and as such the additional weight, complication, and cost of fitting a retractable landing gear are just too much to seriously consider. Fixed gear could be an option too, but often these spoil the aesthetics of a nice streamlined racer-type model or scale EDF and looks are important too. Without these said complications landing gear is just one less thing to worry about but only if you know the best way to hand launch a model.
Ok first let's start with the prop model, in this case, a low-wing model from the H-King Reno Aces series, but the same principles are applied to other low-wing models such as EFX Racers, Durafly warbirds etc. First, always hold the model (whatever the configuration) on the balance point (CG), this ensures the model is balanced in pitch when held and launched which will give you a smooth pull-out right after you let go. Now as this is a low-wing model you will be holding and throwing in an underarm fashion. The most important element to take into consideration with a prop model is the rotational torque caused by the tuning prop and motor. This torque effect causes a roll to the left movement and the effects of this increase with power so for this reason you want to A) hold a little bit of right aileron in on the sticks as you launch and B) never launch at full throttle (otherwise you'll roll left directly into the ground) around 2/3 - 3/4 throttle is adequate. Also whilst holding in that right aileron you'll want to be holding in a little up too, just to ensure the model climbs on launch. So at this point, you now need to apply some power, but how to do this when one hand is holding the model and the other the radio, well this is where your chin comes in handy. Use your chin to nudge the throttle open to that 2/3-3/4 point and then bring your arm down and back (it's a low wing model so the launch is from an underarm throw remember) and with your arm straight bring the model forward and up and release the model when your arm is at its highest point. All of this takes just a matter of seconds, but check out the video and you'll see what we mean.
Now EDF launching is somewhat easier as you don't have the rotational torque to be so concerned about but you also don't have as much airflow over the control surfaces (a prop model is blowing air over the controls even when the model is not flying, an EDF model gets its control from air being pushed over the control surfaces, so you need to build up this airflow asap). This translates to saying that an EDF must be launched at full power to get the air flowing over the control surfaces as quickly as possible. In this example, the EDF is a mid-wing model so calls for an OVERARM launch (same for high-wing models) as an overarm throw allows for a better grip of the model on launch as you can grip the fuselage easily. Now other than the throttle setting and the stance of your launch, everything else in the sequence is the same, hold the model at the balance point, grip in the correct launching configuration, hold in a little up elevator and right aileron, apply the power required (full power in this case with an EDF) using your chin to move the throttle stick, bring your arm forwards and up, and release the model.
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