BO-105 engine RPM
 

Hi All,

can someone tell me what is the design RPM of Bo-105 engines?

The information I found are contradicting. Somewhere I read 6600 RPM. On the other hand, somewhere else I found that BO-105 tail rotor rotates with 2220 RPM and has gear ratio 5.24. This makes 11630 RPM at engine shaft.

thanks in advance

From BO105 TCDS

BO105A = 6,000 rpm
BO105C & S = 6,016 rpm
BO105LS = 6,136 rpm

As per the flight manual of the BO105CB-5, you have

At 100% N2, the engine shaft is rotating at 6,000 RPM. The main rotor rotates at 424 RPM. The tail rotor shaft coming out of the main gear box rotates at 2,452 RPM. After the intermediate gearbox, the tail rotor shaft rotates at 3,065 RPM and finally after the tail rotor gearbox, the final rotation speed is 2,219 RPM. You 5.24 ratio is between the main rotor speed and the final tail rotor speed (2219/424=5.233).

Hope this helps.
Cheers

BO-105 engine RPM
 

turboshaft, ECL_FTE thank you both for the answers.

Nickel,
The 6,000 rpm fiqure is the output shaft speed from the engine reduction gearbox, the compressor actually runs at about 52,000 rpm and the power turbine at 35,000 rpm.:8

I have zero time on turbines :( , but a bit of an idea of how they work. I thought the compressor and turbine disks were on a common shaft, but according to your RPM specs, that's not the case. Please educate me...

Um... Lifting... that is one of the most clear and concise explanations of the free-turbine engine that I've ever read. Nice job!

One slight expansion though...Yes, but... As you explained, in a turbofan, after (or "downstream") of the gas generator section is another set of turbine wheels. These are connected by a shaft (a separate shaft from the one that connects the gas producer and compressor) from the back of the engine to the front of the engine where the big fan is on modern jetliners. It's this shaft-within-a-shaft business that makes the whole shebang work. It also allows for the turbines to instead drive either a propellor or a driveshaft to the transmission as you aptly described.

With the exception of Lynx drivers, who excert a little extra effort in their banging. ;)