Three Dee Rigid II self destruct in mid-air

Once in a while it strikes you: What goes up must come down. However, this time it did not come down easily. After a speed flight test with the new SLS SPEED lipo’s I put in the old SLS APL V2 cells. They are fine for normal 3D flying and having some extra flight minutes.

Coincidentally, a fellow pilot from my flight club wanted to film me doing some stunts. I started flying and everything seemed normal until after just one minute, disaster hit…

Crash of my Henseleit TDR II

Today I flew my beautiful Henseleit TDR II. Bad luck, in mid air the helicopter exploded. My guess that the battery separated from the helicopter by an front flip and pushed the canopy , speed controller in the rotor-head. I am 100% sure i tighten the battery tray screws correctly. Just some bad luck.

Publiée par Pitch-Play sur vendredi 11 mai 2018

When it happens, you start analyzing.. What happened, what did I see? Did I forget to….?

After some analyzing at home, watching the movie again and again and thinking everything through, the only conclusion I can make is that

  • the canopy hit the rotor blades;
  • and maybe the battery tray pushed the canopy in the rotor or the battery tray degraded from the chassis from the vibration.
Canopy hitting the rotorblades

But how could this even happen? I think this happened because I adapted the mounting holes for the canopy to fit the new SLS SPEED lipo’s which are larger. This was done so that the canopy could hold both batteries. Since I adapted the mounting holes for the canopy for the new lipo’s, the older SLS APL V2 Lipo’s where not fixated tightly anymore. What could go wring? The batteries were also fixed to the main chassis by 2 big screws.

The refitted mounting holes.

This is in my opinion the cause of the mid air destruction of the TDR II.

Damage? Well first of all I have to say that the chassis is extremely robust, all internal parts are undamaged even the main shaft and blade shaft have survived the crash. This is probably due to the fact that in the air all kinetic energy was out of the rotating blades. Only the potential  energy was left (falling down).

Damage report:

  • RotorTech 810mm main blades
  • Tail boom
  • Tail rotor shaft
  • One part of the battery tray
  • The Kontrinik Kosmik
  • And some small parts

The Kontronik Kosmik did also suffer the energy of the main blades. The cooling ribs where damaged, but what made me worry a bit more is that the cable contacts where bent. The speed controller was sent to Kontronik for inspection.

The Kosmik speed controller after is encounter witth the rotor blades

After a few days of letting it all sink in, I could start rebuilding this great machine and learn about the mistakes.

Don’t modify the canopy mounting holes and ensure good mounting of the battery tray.

Here some additional crash pictures, you can see that the mounting screws for the battery tray are still in place!


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