A power upgrade – Can I tame the beast?

As you’d expect from such a detailed and well thought out Swiss design, the Rigid 2 is a mighty beast, making near 9 horsepower.  Lately, I have taken the beauty out for a few test flights and while the flights were made in the chilly Netherlands with temperatures close to zero, you could say I barely paid attention to the temperatures while taming the beast.

The Rigid 2 is still in the setup phase, meaning that the Vstabi Neo controller parameters still need some adjustments after each (test) flight. The first flight impressions of the Henseleit Rigid 2 are, to describe in one word: Great. The engine and the 810mm blades  create an unbelievable sound experience (see video here). You can literally feel the amount of power at your RC-controller when you lift off the 6 kg machine up from the ground. The power in the flying beast wants to be released! Speed flight, gigantic loopings, pitch-pumping or just calm and easy inverted lawn mowing, this machine can do it.

The pyro 800-48 Henseleit edition
Taking the engine out of the helicopter. That is an easy job.

Replacing the Pyro 800 for a Pyro 850 Competition

The current engine in the rigid 2 is a Pyro 800-48 which can deliver up to 5 kW (6,8 PK) and suits the machine perfectly. Also used for the Rigid 2 is the Pyro 850-50 Competition version , known as the ultimate power engine.. This Pyro 850 can deliver up to 6,5 kW (continuously) which represents 8,8 horsepower! This engine just beats out the Pyro 800-48. Sibling rivalry?

PYRO 850-50 Competition

  • 55 mm freie Wellenlänge
  • 605 g
  • 6,5 kW
  • 8 mm Welle
  • 7 mΩ Ri
On the left the Pyro 800-48 and on the right the Pyro 850-50 Competition


Knowing that P=U*I (Power equals Voltage times Current), and the battery pack is 14s (fully charged 14*4.2Volt=58.8Volt  and with load 14*3.7Volt=51.8Volt) means that the current at maximum continues load be 6.5kW / 51.8 Volt = 125.5 Amps! The kontronic speed controller can handle 200Amps and 400Amps PEAK so that should work fine together.

The rigid 2 gears can handle up to 15kW but with the new setup the batteries are the bottleneck in the system. The 14S 4400mAh lipo pack is empty within 4 minutes when pushing the Rigid 2 to the max. At low speed and soft flying of course 8 tot 10 minutes could be achieved.

2018 will be the year of me flying the rigid 2, having fun with this extreme machine, enjoying every flight knowing that this machine can do everything, but can I tame the beast?

Some small comparisons:

  • Formula1 car weighs 605 kG and has 730 HP => 1.2 HP / kg
  • Rigid 2 weights 5.9 Kg and has 8.8 HP => 1.5 HP/ kg
Taking the Pyro 800-48 out of the Rigid2

And now putting the new power beast in the Rigid 2.

Connecting the engine with the speedcontroller.

The engine fits perfectly, only I decided not to put any connectors between the motor and the speed controller. Not just solder the wires together! Make it a perfect connection with as less cable resistance as possible, resistance would only lead to heat production and at the end a crash could occur when one of the connectors de-solder during flight. The idea is to use the female part of a 5mm gold connector and put it full with solder and put the engine connector in the part where normally the male connector would come. This way there is no connection resistance and perfect FIXED connection between the engine and the speed controller.

Connecting the engine and the speed controller without a connector.

With this all in place was time to fix the engine in the Rigid 2. Putting just enough clearance between the gear of the engine and the main gear is a tricky part. It should fit perfectly and I left a very slight clearance to overcome production of heat by friction.

Engine gear and main gear with a very small tolerance.

After that it is only a matter of putting it all back together and fixing the cables properly. Making sure there is enough clearance and no tension on the wires. This my result!

Now, let’s get out there and do some flying!


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