Rotax 912

[skippydiesel]

Just thought I might try & stimulate this conversation:

 

After reading the Savannah (912 ULS) performance claims :

 

Stall 26 Knots

 

Cruise 91 Knots @5000 rpm

 

Max Cruise 100 Knots @5500 rpm

 

I am not surprised that the Savannah consumes more fuel, at a given air speed than the ATEC Zephyr:

 

Stall 32 Knots @ 450kg

 

Cruise 116 Knots @ 4800 rpm

 

Max Cruise 125 + Knots @ 5500 rpm

 

My Zephyr, with the ground adjustable prop set to advantage climb (the above would be a cruise or CS  prop setting) is doing an easy 100 + knots @ 4800 rpm (sea level).

 

My interpretation is that the Zephyr's 912 @ a given airspeed , is just not working as hard as the Savannah's 912 at the same airspeed. ERGO my 912 is consuming way way less fuel.

 

 

[facthunter]

 Because at a given airspeed it's using less horsepower. Overcoming drag is a squared  situation. Double the speed  four times the power required.  Overpowering a draggy plane only gets it off the ground quicker. To cruise faster is too costly. ( and probably nudging Vne). Nev

 

 

[Kyle Communications]

VNE on my sav is 108 kts...its a much draggier airframe

 

 

[Downunder]

Zephyr, 450 kg mtow?

 

 

[skippydiesel]

Zephyr, 450 kg mtow?

Hi Downunder -

 

European Zephyr max take off 450 kg  - so all factory figures at this weight.

 

Existing Australian registered Zephyrs have a permit to go to 544 Kg (cant understand why it is not 545 kg).

 

New ATEC imports to AU are now at 600 Kg.

 

To the best of my understanding, all of the weight changes have been without structural change to the aircraft - my interpretation - Max TO Weight in this aircraft has/is a bureaucratic convenience to meet jurisdiction requirements, rather than the true capability of the aircraft .

 

 

[skippydiesel]

I forgot to mention with the increase to 544 kg TO,  the stall speed rises to 35 knots for the Zephyr.

 

The Faeta at 600 kg has a stall of  32 Knots.

 

Both of these aircraft have a sub 100 m TO, ground role @  MAX  weight. 

 

Depending on brake system selected can also have a sub 100 m landing role

 

VNE

 

Zephyr 143 knots

 

Faeta 157 knots