SonexBuilders.net

Looking at a nice Onex, but with empty weight of 712 lbs (Tricycle gear) and my weight of 250lbs, I will be over the "aerobatic gross weight" for the aircraft before I put any fuel in. I understand that the 950lb limit is for safety when puling Gs in aerobatic maneuvers, and to limit wing loading for LSA category. There is one thread on this that quickly went off topic.

I figure that with full fuel I would tip the scales at about 1050lbs. What if I just want to do 45 degree clearing turns and have a private pilot ticket? Are there any here that can comment on flight characteristics with the 80hp AeroVee 2.1 in a Onex at 1050 lbs? Or is this where dragons be?

Quick response is that over aerobatic weight and under MGTOW you are in utility category which is +4.4 g’s. Be very aware though that if you lose control maneuvering you will very very quickly exceed airspeed and g limits.

You don't say where you would be flying-elevation of home airport?? I would be very very very careful of density altitude. Also is the engine truly 80 hp? If the engine builder set the compression ratio lower in order to burn mogas, your horsepower and torque will be a little less.

As a general comment - I try and avoid flying ANY aircraft at gross. I prefer to utilize 80% of usable and no more. In most small GA I've flown that makes a remarkable difference to performance. Especially if things go south.

With an 80hp AeroVee in a Legacy Sonex - it serves me well. Especially in aforementioned higher DA'.

To your specific - you look legal. But legal and sensible are often two different things.

YMMV

I've thought it was odd that they only publish the aerobatic category gross weight, and I've never found a higher gross weight listed. This is the closest thing I could find from Sonex about it. https://www.sonexaircraft.com/documents ... visory.pdf

Rusty

prhutson wrote:Looking at a nice Onex, but with empty weight of 712 lbs (Tricycle gear)

That OneX weighs 85 pounds more than my standard gear OneX. I have flown it for about 6 years, approx. 275 hours.

If you are going to fly on high density altitude days I predict that you will find the climb performance to be barely satisfactory. Think hard about the lengths of the runways that you'll be using. Are there obstructions at the ends?

Does the OneX have the full wing span? The builder could have shortened the wing tips, which gives you better roll response, but also reduces the wing area thereby increasing the wing loading and reducing climb performance. Something to think about.

Wow, the empty weight is more than 100 pounds heavier that my TD Onex. I am suspicious of the accuracy of that empty weight. That 950 weight limit is more than a acro max weight. I am sure that being flown above the 950 pound limit will decrease that climb rate, increase the stall speed, and worst of all the increased wing loading which will yield a higher best glide speed resulting in a much higher sink rate with power off. I personally would insist on a reweight on certifies scales before I would move on making an offer and would see the 712 pound empty weight as a possible purchase no go.

The original builder (manufacturer) of the Onex sets the max gross weight at time of FAA certification and it is recorded in the aircraft log books. I do not know what the builder set the Max gross weight at, but it is mostly etched in stone at this point. As a subsequent owner you are not permitted to change the max gross weight without going back through the certification process and as not being the orginal builder I highly doubt that you will find a DAR or FAA rep willing to accommodate the process. Without a change you would probably be flying outside the design limits in violations of the operation specifications and would be challenged by the FAA and you will likely find your insurance to be considered void if you tried to make a claim while being flown above the published Max gross weight.

Just my thoughts,
Pete

Good point about the accuracy of the weight. Is there anything that stands out as substantially heavier than normal? If the reason isn't obvious, you do have to start wondering if the scales were accurate, and if maybe they weighed it with full fuel or something silly like that. There may be a way to reduce the weight as well (Earth-X battery, remove unnecessary equipment) but probably not 100 lbs worth.

Rusty

Good points. Builder/owner may try to re-weigh.
Of course another approach would be for me to lose 30 pounds... nah.
GWT in the plane's documents is 950, although it wasn't flown or signed off as aerobatic.
I'd be flying out of C29 at 1000 MSL and 4000' asphalt, but on sunny days density altitude is easily 2500. What kind of climb rates do AeroVee 80hp Onex pilots see at 2500ft and at 950lbs?

The discussion about the heavy Onex is the result of my mistake in re-weighing the plane with fuel in the tank. I re-weighed the plane several years after the original empty weight weighing before it was flown. I subtracted the weight of the fuel from the final numbers without realizing that the fuel in the tank also adds to the three landing gear weights mostly effecting the nose wheel. As a result the "new empty" weight that was mentioned above was over 700 pounds. The original and official empty weight was 670.2 pounds with no fuel. Sorry for the bad math that led to this discussion.