Broken Mounts

broken motor mountHrrrm. I’m having some trouble with the mounts for my brushless motor. The motor itself is freaking fantastic. The power generated is more than enough to pull into an almost unlimited vertical climb directly after take off. It’s the mounting that is pissing me off (absolutely no complaints about Aircraft World though, they’re the best international RC flight suppliers around).

The mount is made of fairly soft aluminium, but has absolutely no problem handing the power of the motor and prop. It’s the landings that are causing trouble. At the suggestion of many on the fantastic rcgroups.com forums, I removed the flimsy landing gear from my Formosa and use a hand-launch technique to get it flying. Landing is a fairly inelegant belly skid, which actually ends up a bit less stressful because the landing gear would result in a nose-over more often than not. However the broken mounts are coming from prop-strikes against the ground during these belly landings.

Suggestions to avoid or reduce the prop strikes are varied. The camps are split over whether to enable the propeller brake on the speed controller, some saying a freewheeling prop can swing out of the way when it hits the ground, and others saying a stopped prop is safer, as long as it is stopped horizontal of course. In practise, a freewheeling prop spins damn fast due to the airspeed of the plane when landing, and I’ve broken two mounts in this setting. A braked prop is fine, but it requires continual ‘blipping’ of the throttle on final approach to get the prop to stop in the right place. This is a no-go during any difficult landings (e.g. in wind, on low battery, or when a random dog approaches – basically anything that requires more concentration). I’ve broken two motor mounts when flying with prop braking enabled.

So yeah, not good. From here I’m going to try a couple more $5 motor mounts to see if I can perfect the braked-prop belly landing, but otherwise the landing gear is probably going to have to go back on.

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2 Replies to “Broken Mounts”

  1. It’s more the fact that the flimsy stock landing gear is prone to bending, and the small wheels catch in the grass.

    Something like this might be more robust and also more streamlined. I’d have to build a custom mounting point on the fuselage (as opposed to the current wing LG mounts). Problem being that a hot landing on long grass would probably break the landing gear or fuselage rather than bending the LG as currently happens. I think it might be the ultimate solution however, because I’ve pretty much perfected the delicate landing required when belly landing. Nice non-bending landing gear coupled with some balloon-style tyres could do the trick. Or should I just spend the $30 on 6 motor mounts?

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