Sport Pilot Talk

“How is it having to deal directly with the importer”
It is actually better in my opinion (not that I had a choice). Everybody in the network (owners) gets the same information at the same time.


“What is a realistic cruise speed?”
For me flying solo and 90lbs of fuel I see 1100-1200 fpm climb and 125mph cruise. Keep in mind that I run mine at 5000 rpm or above in cruise.

James

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EuroFox N617B

Well here is a picture taken by my passenger on climout where I am just about levelled off, still climbing at 100 fpm. We had full gas 134 lbs and 500 lbs of meat in there. I know,,, transponder is on STDBY. Darn pictures anyway.



I have never ran it full out except on climb out which is typically 1000 fpm 2 up and better with just me. And that is usually at 75-80 ISA. It will run 110 for me at 42-4400 rpm and <4 gpm of gas and an easy 125 ISA at ~48-5000 rpm. The craft is incredibly quiet and smooth. The 912 is clockwork. Very exciting plane to fly. If you are near one somewhere, ask for a ride. I live in Bakersfield, CA. and always looking for passengers.

Gary

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GARY N ORPE

42-4400 isn't a healthy range. too much vibration for your gear box and not enough fuel/air mixture getting to all cylinders. 48-5000 is low as well

i run mine at 5,500 in cruise.

I'm a home builder and still considering what engine to use. What's up with the restricted RPM ranges with the Rotax? This looks like a big negative to me. Is there information in the Rotax manual about preferred RPM ranges? Some folks on the builder's list I frequent say they have had there engine/props dynamically balanced and it makes a huge difference on engine smoothness throughout the RPM range. Is this something you have looked at? I'm just confused by the RPM issues.

Ron

true, dynamic balancing will or can reduce vibrations throughout the rpm ranges.

it still remains true that the gear box will hold up better if idled at 1,700 rpms minimum and if cruised at 5,500 or close too it.

many SLSA come pitched to coarse to realize 5,500. if you are that course than you cannot realize the power the 912 is capable of producing. it is only 100hp at 5,800 and less at fewer rpm.

the gearbox has less tolerance for roughness than the human ear. this rpm range issue has been coming from rotax through their training classes for a long time. recently we are hearing that the 5,500 range or close to it is needed for delivering the same fuel/air mixture to all 4 cylinders.

So if I am getting 5300 rpm WOT then are you saying I should run WOT all the time to burn the water of whatever from the oil or what ever it is?

James

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EuroFox N617B

James,

Actually you should look at having the prop repitched. If the engine can't realize 5,800 rpm's, the prop is pitched too coarse. My CT was delivered to me seeing max rpm's of approx. 5,200. It was fast, but it was going fast at the expense of overloading the engine. Flying at lower altitudes it was ok, but once I was flying at higher altitudes, I was seeing max rpm's of 4,900 and performance really lagged. Climb performance suffered as well.

At the time I was was seeing max. static rpm (full throttle on the ground) of approx. 4,700 rpm's. I've since had the prop pitched to realise 5,000 rpm static, which allows me to exceed 5,700 rpm's at WOT. It has been a good trade off in terms of climb performance, with just a slight loss of speed, and minimal change in fuel economy.

Rotax recommends not running the engine at cruise below 4,800 rpm, due to vibration issues. They would rather see cruise at about 5,200 - 5,300 rpm. These are at sea level. This doesn't mean you should run at WOT, but rather that you should repitch the prop, than throttle back some to realize your best speed and economy trade off.

no,

i'm saying to realize more power you would need to have your prop adjusted a little flatter. makes more sense to optimize for cruise which is 5,500 wot than climb which could be up to 5,800 rpm because at best cruise power climb is still quite good.

you can still elect to fly with the throttle partially open and if you are pitched for 5,500 wot you will see better performance / economy, at least that is true in a ctsw.

the 912 was designed to run at 5,500 all day long and if you like less than you will realize more vibration and even uneven fuel distribution.

All makes sense so far!

Does the engine know the difference between 5300 WOT and 5300 with a little flatter prop?

I wonder how my Fiti Prop figures into this equation. Fiti designed this prop we Eurofox drivers use specifically for the rotax 912 series engine.

Just thinking out load!!

James

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EuroFox N617B

Yes, it does. In order to turn the coarser pitch prop at 5,300 rpm, the engine is working harder, but is being limited by the prop. This is putting additional stress through the engine, that Rotax calls "loading". Loading the engine will cause the engine to wear quicker, and could cause failures. Personally, I think the root cause of the gearbox recall has something to do with this.

similar to asking if your car engine knows the difference between going 15mph in 1st gear and 4th gear.

by re-pitching flatter it would be like downshifting to a better gear

the water issue you mentioned is about getting your oil temps above water's boiling temperature. this will cause any condensation in your crankcase to boil away

So is this where the adjustable pitch prop comes into play on "complex" aircraft?

in-flight adjustable i mean

a constant speed or a in flight adjustable prop allows you to optimize your pitch in flight. no compromise needed, flat pitch for take offs, towing, climbing, coarse pitch for cruising, (blending speed and economy)

Gary O.,

Nice photo of your EF panel! I also noticed you were squawking "standby".

The craft is incredibly quiet and smooth. The 912 is clockwork

I have an observation/theory about why the EF may be so quiet. First the Rotax engine probably runs pretty free of very coarse vibrations because of it's higher rpm range (higher than a Continental or Lycoming for sure), which translate into the lack of large pulses caused by a larger displacement cylinder. Secondly, the EF airframe is welded steel tubing which I assume gives much more "give" and will actually move and twist with torque loads, whereas a aluminum airframe probably doesn't "give" as much to absorb those engine and turbulence vibrations. I'm going by what I have heard (and experienced) about the difference in quality of ride between a welded steel tube and a (also welded) aluminum bicycle frame.

I also know for sure that my old and smallish Luscombe is very loud, and it has a relatively slow turning (2200 rpm cruise) Continental and is made of riveted aluminum. I have the best ANR headset I can get my hands on.

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WSW