AeroVee RPM on first flight

[Bryan Cotton]

Craig,
My only Aerovee experience to date is packing the boxes under my brake. However congratulations on the first flight!

[Gripdana]

I have 50 hours on my Aerovee I get between 3000 and 3100 on take off. I do much better closer at sea level and standard conditions. My performance is very close to Sonex published. I am curious to know what were the weather conditions and field elevation of the first flight? I fly out of a field that is 2,351 MSL and on an over standard day I lean for takeoff to get better RPM. I am getting 3200 to 3400 in cruise when I lean properly.

[ccm]

Thanks everyone for the help!

From the responses here I will try the following:

• Richen up the mixture possibly trying the number 3 needle
• Check secondary timing is really in sync with primary
• Install the gear leg fairings for a bit more speed

Dana, the airfield I'm based at (Chichester Goodwood) is just above sea level at 110ft. Temperature was around 60F with relatively high humidity.

[SonexN76ET]

Craig,

As you attempt to improve the RPM, I recommend you do it one step at a time. Make an adjustment, see if that helps and then move on to the next thing. If you try everything all at once you won't know what actually helped. Do your adjustments incrementally. The exception is the gear leg fairings, do those up front and if possible the wheel pants too.

When adjusting your mixture needle do it in 1/8th increments or less. Do not forget to lock down your throttle open before making the adjustments or you will kink your throttle cable. Follow the instructions in the Sonex manual to the letter. I would not switch needles until you have used up the settings on the current needle.

Also on the secondary ignition, the timing changes are done in extremely small increments. It is hard to see exactly where the dot is on the trigger magnet, you can make a reference mark on the accessory case and the trigger to show where your starting point was, that way if you go to far one way or another you can go back to your exact start point.

Good luck and congratulations once again!

Jake

[ccm]

Carburettor heat, required by Light Aircraft Association in the UK, appears to be the problem here. Removing the scat hose and installing the air filter as per plans allows 3200RPM in flight!

I'm now going to have to see if I can get the requirement for carb heat removed...

[gammaxy]

Congratulations on figuring it out. That sounds like something that could potentially have a larger effect than the other suggestions. I would still think carb heat can be done without sacrificing power (bigger hose?), but getting an exception might be nice.

[xymox]

IN my case (and Im still getting it tuned correctly) the previous builder had accidentally left a set screw inside the aercarb which was acting as a stop to the slide, it was just floating around in there and only reason I found it was because I decided to open up the carb to see what makes it tick, imagine my suprise. after removing that the throttle was definitely able to open up further but did manage to balk a little bit from opening too far. I know this max wot setting needs to be adjusted correctly or that balking will occur. Interested to see results once the thing is in the air.

[gammaxy]

Xymox, welcome to the forum.

Before you consider limiting how far the throttle opens, make sure you've got the mixture adjusted correctly. My understanding is that limiting the throttle throw is rarely required for an Aerovee Sonex with the recommended propellers.

If you are too lean, it will only get leaner as your airspeed increases and the engine turns faster.

[xymox]

Xymox, welcome to the forum.

Before you consider limiting how far the throttle opens, make sure you've got the mixture adjusted correctly. My understanding is that limiting the throttle throw is rarely required for an Aerovee Sonex with the recommended propellers.

If you are too lean, it will only get leaner as your airspeed increases and the engine turns faster.

Well ill apparently have to adjust once I'm in the air and use the 90 degree drop at full rich to tell. I'm using the number 3 needle as the number 2 was making the aerovee sound like a Harley and not in a good way. Lowering the idle to anything below 1000 rm resulted in engine dying. Seems to have good power for the moment with good throttle response.

Here's what my 900 rpms sound like right now.

https://youtu.be/WXhoUyK5Qbo

[xymox]

I recind my statement. I was able to do a full throttle pull under static conditions and I pulled my mixture back about three quarters of an inch and I was able to sustain about 3200 RPM's. Now that is with the throttle limited by about a quarter to three/eight inch but I suspect I can open it up all the way and get even more RPM's at this point