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Real performance numbers with an Aerovee

PostPosted: Tue Jun 24, 2014 9:50 pm
by Fastcapy
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Re: Real performance numbers with an Aerovee

PostPosted: Tue Jun 24, 2014 10:39 pm
by corton
Hi, Mike;

You don't say too much about your configuration, so will just give some general information (TW vs Trigear, weight, etc.)

I'm in a TW Sonex at 662 lbs. You also don't say how many hours you've accumulated. The AeroVee won't loosen up until OVER 25 hrs, so don't sweat your performance at this point. You also don't mention if you have the pants/fairings installed. Sonex LLC won't even talk to you until you tell them you have 'em installed.

If you climb at 60 or 65, you'll see the advertised numbers. But then again, you don't want to climb at those speeds until the engine is broken in. You want as much air going over those cylinders as you can. I rotate at about 50-55, keep it at 75 until about 400' AGL, then keep in a 95 mph cruise/climb to keep the CHTs down.

At full gross, this flies very differently. Much greater effort to raise the TW on takeoff roll. Not bad, but different enough that you start thinking about IT instead of flying the plane. On a 85 deg day, at full gross, it performs about like a 172. Meaning about 300-350 FPM climb. Where *I* fly, that's not an issue. I'm also flying at a higher gross weight.

Concentrate on your CHTs, oil temp & pressure, and EGTs at this point; get your airspeed work (stalls, etc.) down, make sure it flies straight, etc., have some fun with it, then concentrate on the weight testing and max perf / short field / Vx-Vy testing after you're satisfied with the engine.

You also didn't say what kind of RPMs you're seeing. Most of us see about 3200 on takeoff roll, and leveled out up to about 3400 RPM. Your timing could also be off a bit. One way to check this is to establish yourself in a level flight attitude, at some decent power setting (2900-3100 RPM). Turn off your secondary (i.e., electronic) ignition. If your RPM's climb and CHTs decrease, you're too far advanced on the secondary. I don't care if the pri and sec are dead even during your run-up. It's in the air that counts.

Unfortunately, it's not just build and fly. There is some evaluation and tweaking involved. Unrelated anecdote: #2 son is an ATP flying ERJ-145's. He says to me, "I'm a better pilot than you." To which I reply, "Yeah, but *I'm* a TEST pilot!!" He'll just smile and say, "ya got me there!"

Re: Real performance numbers with an Aerovee

PostPosted: Wed Jun 25, 2014 10:19 am
by radfordc
I would suggest not even attempting to match the factory numbers until you have more time in your plane. Engine performance will improve over the first 25-50 hours and your "feel" for the plane will also improve.

Routinely I see somewhere in the 800-1000 range for takeoff. I climb at 85-95 mph for cooling and usually see 500-700 fpm solo and 300-400 at gross. I'm at 1000 MSL field elevation, so when it's hotter and higher these numbers are less. I've never been off the ground in 400 feet or seen 1250 fpm rate of climb....but who cares. I've got a plane that will fly at 120 mph on 5 gal/hr, do basic aerobatics, and pegs the "fun meter" on every flight.

Re: Real performance numbers with an Aerovee

PostPosted: Wed Jun 25, 2014 12:42 pm
by Rynoth
I questioned Jeremy on the factory published numbers during a Flight Testing Webinar back in November 2013. Based on the data they were collecting, they weren't getting near the published numbers either, and Jeremy himself said that they should "revisit" those published numbers.

Here's the webinar. I ask the question at 1:22:05.

http://www.eaavideo.org/video.aspx?v=2838784112001

Re: Real performance numbers with an Aerovee

PostPosted: Thu Jun 26, 2014 8:12 am
by planeolbob