What happened to the Maule?

Heimi... Apologies for not replying sooner.

I also don`t understand what you want to tell me with that.

Maybe I generalized/simplified my description too much.

That I do not understand what you mean by "full power"... does that mean max throttle? max MAP and rated RPM?

Btw, thanks for the link. I do not know how much I put stock in the car / transmission idea (actually from what I know of how engines/props work, I do not like it). That analogy would work just fine if comparing to how a bicycle works (gear ratios etc.).

Full Power doesn`t mean full speed!!!!

"Full Power" is obtained by using maximum manifold pressure (full throttle) at max RPM (2700rpm in this case) and at Sea Level @ Std Temp & Pressure the Maule IO-540 should be able to develop 260hp. And that is what is needed to obtain max speed.

By reducing prop angle you gain speed and loose power.

You cannot decrease the % Power being developed by an engine and obtain more speed.

88% is recommended for climb, and 70% for cruise.

For a normally aspirated, direct drive engine with a prop governor (like our Maule engine) Lycoming generally recommends 85% Power for the climb, BUT (and this is a big but) you absolutely have to go to the specific engine manual to determine what the correct procedure / power setting would be. General recommendation for cruise (Lycoming) is 55% - 75% Power. But again... check the manual!

Speaking of these power settings... again for those that have looked at the Cirrus POH, it should be clear that the only way to set a known % setting is to go to the appropriate chart and determine what the correct MAP and RPM should be based on (Pressure) Altitude and Temp. Hopefully it is clear that the % Power displayed in the HUD is the % Throttle setting... which is NOT the same as the % Power the engine is developing.

Great Ozzie,

 

Try climbing above 15k in the Maule. Once you get there, the only way I have found to keep climbing is to reduce RPM.

Thanks Oracle... appreciated.

Btw guys & gals...

A strictly fwiw (i.e. a "ok go ahead and bore me with some RW details...)

I checked for some sort of documentation about the Maule having a Service Ceiling, Absolute Ceiling (or otherwise) and could not find anything other than in the TCDS (Type Certificate Data Sheet)... and that only for the M-7-420AC.

Note that "420" is an indication of the horsepower (420 HP???) that the engine develops. Yes... well almost. The M-7-420AC uses a variant of the Allison 250, a gas turbine engine that many will recognize used on a variety of helicopters... very well known in the Bell series of helicopters (like the FSX Bell 206). The Allison 250 series HP starts around 420HP (and continues much higher HP depending on variant).

The light weight, relatively small size and high HP output of the Allison 250 lends itself extremely well as a substitute for the larger Lycoming and Continental engines... those in the in the 300HP range. In fact (some reading this already know, apologies) aircraft such as the Beech Bonanza, Cessna 206, P210 (pressurized cabin) and Cessna 340 (twin) have conversions available for the Allison 250.

Back to the Maule. Typical of the conversions, the Allison 250 is derated (HP limited)... for the Maule to 370HP. As I said, I found something in the TCDS for the M-7-420AC... in this case a Maximum Operating Altitude of 20,000 feet. Whether this is based on the operating limitations of the Allison engine or a function of the "excess thrust" available for climb, I have no idea. Excess thrust is what is needed for an airplane to climb (that in excess to maintain Straight & Level flight)... so it is entirely possible the Maule (specifically the 260HP version we have) has a service ceiling less than 20,000'.

So happy coincidence or???

Rob O.