Onex cruise numbers MIA

[Echo Tango]

I realize the ones cruise will likely be very close to the 135 at sea level allowed by LSA rules, but there was some talk of the aerovee being RPM limited to keep it within LSA. Haven't heard any updates on this. Was wondering if anyone else had any current info?

[radfordc]

I have heard that if you install an Aerovee that isn't rpm limited....you will cruise about 170 mph! (probably not at sea level)

You can be sure that Sonex LLC will sell you a "legal" engine and yes that particular engine will no doubt be limited to some lesser rpm for "continuous" operation (they already do this with the Jab 3300). You will still be able to use full power rpm for "limited" periods of time.

[Mike53]

I have heard that if you install an Aerovee that isn't rpm limited....you will cruise about 170 mph! (probably not at sea level)

You can be sure that Sonex LLC will sell you a "legal" engine and yes that particular engine will no doubt be limited to some lesser rpm for "continuous" operation (they already do this with the Jab 3300). You will still be able to use full power rpm for "limited" periods of time.

Your just about on the money .If you watch the video he is doing 175mph at 3400rpm http://www.eaavideo.org/video.aspx?v=812884718001

[Dan]

I think I have watched that video at least 10 times. It's the closest we Onex builders/dreamers can get to flying one ourselves IMO. I'm ready for them to make another video for our entertainment.

[GOIX]

That was in a dive though ;)

Marc

[Dan]

I have to say I am confused. Not an abnormal condition for me :D Sonex says the Onex meets the sport pilot rules but then has a video showing the Onex exceeding the speed limitation by a large margin. Oshkosh is not that far above sea level. What am I missing here? Is this for the prototype only?

[radfordc]

I have to say I am confused. Not an abnormal condition for me :D Sonex says the Onex meets the sport pilot rules but then has a video showing the Onex exceeding the speed limitation by a large margin. Oshkosh is not that far above sea level. What am I missing here? Is this for the prototype only?

Part of your confusion is the way that the Sport Pilot rule was written. The speed limit for a sport pilot is defined as 138 mph @ sea level @ Vh. Vh is "max continuous power". An engine may be allowed to run at a very high rpm for short periods but be limited to a much lesser rpm for "continuous" operation.

What you saw on the video was the short duration maximum power...not the continuous power. When Sonex sells an engine for the Onex it will be carefully designed to operate at a "max continuous power" that meets the SP rule.

[Andy Walker]

Sonex typically lists cruise speeds at the "ideal" performance altitude, usually 8000 feet for their other product lines. Since the Onex uses the same engine, I'm assuming that a 170mph cruise is at that level. At sea level, you are probably very close to the 138mph LSA limit, maybe a little over without the extended wingtips.

The LSA speed limit is pretty stupid, because there are a million ways to measure airspeed and every little factor affects it. As an aeronautical engineer friend of mine told me once "the problem with a standard atmosphere is that there's never one around when you need it." ;) As long as a manufacturer/builder is in the ballpark, it would be *very* hard for the FAA to to prove you are not completely LSA compliant, since they'd almost certainly never be able to fly your airplane at sea level in a standard atmosphere.

Also, in the Onex video wasn't the high speed shown in a diving pass down the runway? Gravity assist doesn't count. :)

[Dan]

Appreciate the explanations. I will be more than happy if I can cruise along at 150.

[Onex107]

Onex 107 just has a couple of hours on the Aerovee, but, air speed is a combination of rpm and prop pitch. With the Sensenich wood prop and wide open throttle, 3200, I see 140. At 2900, cruise?, I see 130/135. In a shallow dive for a pass down the runway I saw 160. I don't think you will cruise at 150 without some changes from the standard arrangement.