Sport Pilot Talk

Here's the exact wording from 1.1:
(2) A maximum airspeed in level flight with maximum continuous power (VH) of not more than 120 knots CAS under standard atmospheric conditions at sea level.

Granted, CAS and TAS should be the same or very close, but the FAA is using CAS as the standard.

Here is the 1.1 definition of VH:
V H means maximum speed in level flight with maximum continuous power.

Maximum continuous power does not mean wide open throttle. The manufacturer can set the power setting to yield not more than 120 kcas.

Choosing components and settings is informed by the 120 kcas max. The question buying a plane off the shelf is can one change power, prop pitch and drag and improve the VH while abiding by the reg.

_________________
Flight Design CTSW E-LSA
ATP CFI-I/ME/G LSRM-A

And, 75% cruise speeds (a relic from TCM and Lyc engines) doesn't have anything to do with VH. In fact, I'd think witih Rotax and Jabiru engines, 75% power is a useless number. One should run by the manufacturers numbers.

_________________
Flight Design CTSW E-LSA
ATP CFI-I/ME/G LSRM-A

what does it mean when mfr gives speed/performance @ 75% power? seems to me, with fixed pitch % power is just a direct function of max rpm. e.g., rotax 912uls 100% = 5800. 75% = 4350 rpm [seems v low] it'd be nice if they say 5000 rpm, sea level std conditions =110mph but almost never done.

_________________
Remos GX nXES. N999GX
smith ranch/san rafael airport (CA35)
california

if max is 5800, i thought people cruise around 5200-5300?

I wish it were that simple! In fact, for either carbureted or fuel injected ingines, % power is a function of air passing through the carb or injection airbox. You can see that RPM doesn't tell the whole story, if you consider that a given RPM at one altitude will produce a very different power level from the same RPM at a different altitude (considering that air density varies with altitude). Plus, you can point the plane downhill and throttle back, producing a very high RPM at almost no power. Thus, rather than RPM, the best direct indicator of power is intake manifold vacuum (usually, erroneously called manifold pressure). But even that is not a simple linear relationship.

Aircraft power is actually a function of three factors: engine power (a function of airflow for a proper fuel/air mixture), engine torque (a function of engine RPM), and thrust (a function of propeller RPM). The engine RPM that produces optimum torque is generally quite high. The propellr RPM that optimizes thrust is significantly lower, because of drag effects. This is why Rotax, for example, uses a prop gearbox - so both torque and thrust can be optimized simultaneously. As for engine power, since it's related to air flow (and the corresponding fuel flow to achieve efficient mixture), turbocharged engines obviously produce more constant power than the normally aspirated ones most of us fly.

Bottom line: "75% power" is actually a meaningless designation. But, to see a typical breakdown of performance at various power levels for a typical LSA, see the table at http://avsport.org/acft/performance.pdf.



Yes, and according to the above-referenced chart, that's midway between what I call "normal cruise" and "max cruise" for a Rotax 912ULS-powered LSA. Note that Rotax specs the engine at 5500 RPM max continuous, and 5800 RPM for up to 5 minutes maximum.

_________________
The opinions expressed in this post are those of one CFI, and do not necessarily represent the position of the FAA or its lawyers.
Prof. H. Paul Shuch, Ph.D., CFII, LSRM-A/GL/WS
AvSport of Lock Haven
http://AvSport.org fly@AvSport.org

Tecnam will not be importing the 0-233 powered aircraft due to being overweight for the LSA market in the US. I emailed Tecnam to get a clear answer and received the info.

Direct from Eli Grimes of Tecnam North America on 12-8-11 after confirming with the factory in Italy, "We can offer the Lycoming version of the Eaglet in the US, but only with one avionics package option. Without the autopilot it would be $143,000, and with $150,000."

Contradicts previous email but is good news.. What is the useful load and what avionic package is offered? When is the first Demo aircraft arriving?