sanket_patel

Hey all! Just wondering, a couple of collegues and I set up an Baron 58 simulator using FS2004 (projectors, multi displays, throttle, flight yoke, rudder pedals... all we can afford / burrow) as part of our Multi-Engine IFR training in our college (John Abbott in Montreal, Quebec). We find it's a great tool to learn how to navigate with the 99.9% close to real life instruments, however, we read the simulator checklist that we are supposed to cruise at 100% throttle and with approximately 2500-2700RPM with proper leaning. Could anyone confirm that this is the true cruise setting? I find that a little troubling if it were true. (Where's the extra power when you have engine failure?)

411A

You will indeed get the best speed (and reasonable economy) while crusing at wide open throttle and an rpm to approximate 75% BHP.

As the engines on the Baron58 are not turbocharged, lean to peak EGT, then enrichen 25 degrees F. for best results.

sanket_patel

Wow thx for the help! Ill advise the rest of the students.

DFC

When one climbs in the Baron (in this case), you will notice that one has to keep increasing the throttle setting in order to maintain the Manifold Air Pressure. Eventually, you will need full throttle to maintain the required manifold air pressure and any further climb will cause a reduction.

In the real world, provided that less than 75% power is set, the mixture can be leaned for best economy.

So.......the best altitude for a particular power setting occurs where that power setting is achieved with the throttle full open.

If you can get your hands on a manual (ask the manufacturer nicely), it will most likely have settings for 55, 65 and 75% power.

The maximum speed and maximum range for a particular power setting occurs at the altitude where full throttle is reached.

Taking the Seneca as a guide since I have the fugures;

75% Power requires full throttle at 5000ft
65% Power requires full throttle at 9000ft
55% Power requires full throttle at 14,000ft

All the above with 2400 RPM

Or to look at it from a different angle......if one starts a climb with full throttle and 2400 RPM, the engine power will be:

100% at Sea Level
75% at 5000ft
65% at 9000ft
55% at 14,000ft and
45% at 18,000ft..............assuming standard atmosphere!

You can see from the above that using 2400RPM, it is impossible to get more than 75% power out of the engine above 5000ft. That is why manufactures allow leaning in the climb when above 5000ft......you can't damage the engine.

Finally, note that the mixture setting for best economy is leaner than the setting for best power (best speed). Thus, one can not always achieve best range and best speed at the same time.

Regards,

DFC

sanket_patel

Ok DFC, thx. According to my 152 manual (my current aircraft before i fly the twin), the throttle setting does lower to maintain the manifold pressure as you climb. I think I will ask Beechcraft very kindly for a manual for our college. Really appreciate the help DFC!

DFC

The 152 has a fixed pitch propeller. Power is set by setting the RPM. No maniold pressure indication is provided.

Aircraft with constant speed propellers will have a constant RPM set eg 2400 and in order to set a particular power at that RPM need a manifold pressure gauge.

Regards,

DFC