SonexBuilders.net

Greetings,

I'm in the process of trying to calculate the length of the engine mount for my 912 Onex installation. One variable that I don't know is how the CG tends to work out on a normal Aerovee Onex. If you have completed an tailwheel Onex, can you share your CG location? If they tend to be nose heavy, or tail heavy on average, I'd take that into account when building my mount.

Thanks,
Rusty

Hi Rusty,

Here are the numbers for my OneX 169. The datum is as defined in the OneX flight manual. Let me know if I've left out any important data.

Empty weight: 627 pounds
Arm: 59.94 inches
Moment: 37,584.8 inch/pounds
Engine: AeroVee 2.1 (normally aspirated)

Gross weight: 950 pounds
Arm: 63.60 inches
Moment: 60,419.3 inch/pounds
CG is 26.2% of MAC

Hi Rusty,

If you go to the 31 minute point of this webanar it might give you some ideas, https://www.youtube.com/embed/wV_cqkweNzg.

CG Limits 20-32% Wing Chord

Hummel 2400 with bits for cold air induction, after market (heavy) main gear and baggage compartment.
Empty weight 638.5 lbs.
Empty CG is 58.71" aft of the spinner tip which works out to 7.835" aft of the leading edge or 15.67 % wing cord.

I can't go aft CG with me, empty fuel, and lots of baggage with out going over gross when I fill up.

Full fuel,a 150 lb. pilot, and no baggage goes just a tad forward of the forward limit.

Wes

Onex C.G.

I have the Hummel 2400 85 hp. engine, Odyssey PC-680 battery and 5:00x5 tires which are heavier.

Short answer ….with full fuel and my 175 lbs my c.g. is only 3/4" from the fwd limit.

Hope that helps.

Gordon...…..Hummel 2400....Onex 0024

Appreciate the numbers, and the link to the webinar. I added "tailwheel" to the request, since it does seem to make a difference. I know Wes is tailwheel. I'm assuming Michael and Gordon are as well?

If anything, I'll likely lean toward being a little noseheavy, since that's safer, and can be corrected with much less added weight if needed.

Thanks,
Rusty

13brv3 wrote:Appreciate the numbers, and the link to the webinar. I added "tailwheel" to the request, since it does seem to make a difference. I know Wes is tailwheel. I'm assuming Michael and Gordon are as well?

If anything, I'll likely lean toward being a little noseheavy, since that's safer, and can be corrected with much less added weight if needed.

Thanks,
Rusty

Hey Rusty,

About 10 minutes after I wrote my post I remembered that I should have added that my airplace has a tailwheel.

I agree that a little nose heavy is better than tail heavy. In my aircraft I've never had to use full stick forward or aft. I don't fly aerobatics.

Im planning on putting a 190 lbs ish engine with standard mount, I already mounted pc540 on firewall. Going to pay close attention to more replies with what others have.

I finally made it to Weight and balance time, so I figured I'd report the results. I'm very happy with the way this came out, which was part luck, and part calculation :-)

Rusty