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What mods have builders done to make the ONEX faster -- It is really not much different from the Sonex.
Has anyone considered fairing in the valve covers that stick out??
ONEX builder
Glen Bradley

flyingbear wrote:What mods have builders done to make the ONEX faster -- It is really not much different from the Sonex.
Has anyone considered fairing in the valve covers that stick out??
ONEX builder
Glen Bradley

Hey Glen,

What speeds are you currently seeing? What kind of increase are you looking for? Are you using the turbo AeroVee? Which prop? You might be able to use one that is configured more for cruise than climb.

Its about the same weight with a lot less wing area. This means it needs to fly at a higher angel of attack to make the same lift. This creates MORE induced drag than a regular Sonex. It has less frontal area, which tends to make up for some of the induced drag. It's a bit of Cat 'n Mouse...

Its known on Sonex's that wheel pants and gear leg fairings make a noticeable difference. Well the Onex has pants but it doesn't have gear leg fairings. A lot of drag comes from trailing edges. Google drag of round objects and you will see a turbulent wake. We need to put the air back smoothly. So a small fairing on the back of the gear will help. I suspect 1-3 mph. You could also add one under the airplane at the back of the gear.

A small trailing fairing added to the the cowl right behind the valve cover would help. Its an overall small area compared to the entire landing gear but every little bit helps. How about antenna's? They are round and can be cleaned up. How about the tail spring (or skid if you have a nose gear). Nose gear leg?

Some people have added a Rudder gap seal. This would help but I don't recommend these kids of changes unless you are REALLY prepared (qualified) to test them. I also think some speed could be found in wingtip design but its a lot of work to make new ones, after someone does the aerodynamic analysis.

I think Graeme added a small fairing at the flap-fuselage intersection and saw good results with tufts. This would be a drag reduction.

How tight is the canopy? Air getting sucked out causes turbulence, which is drag.

Drag is a function of Velocity squared so its even harder to go faster. Can you really measure any of this? Its hard to say. But if you did it all and found 5 mph, its something. I did all these little things to a Glasair once and found almost 10 mph. I have helped lots of other homebuilders and its pretty easy to find the 5. Its hard to say if we will on the Onex. Of course more power and more fuel burn always makes it go faster :) I do dream of 140 HP to make mine a little rocket ship but its hard to find for a reasonable price and weight.

Scott
Aerospace Engineer

Aeromentum lol, but there are compromises on redundancy

Thanks guys. That is exactly what I have been thinking too. I am not a speed freak but I was expecting more speed than I am getting.

The point about similar weight and less wing area than a Sonex also shows up at altitude. I have flow the same route from western Oregon to Missoula, MT in both my Onex and Sonex. Each has the same Jab 3300 engine and at 11,500 ft the Onex climb rate is minimal while the Sonex is still climbing at a reasonable rate. At lower altitudes the Onex is still the faster aircraft by 10 to 15 mph.

Vince Homer

Flying a 0nex is like bicycle racing.............Going downhill is where all the fun is.
Tom Ryan...0nex 74

tom0nex74 wrote:Flying a 0nex is like bicycle racing.............Going downhill is where all the fun is.
Tom Ryan...0nex 74

They do go rather fast downhill! Here is an example https://www.youtube.com/watch?v=g60mlHu9fdQ

UPDATE ON NEED MORE SPEED BY GLEN BRADLEY/FLYINGBEAR: APOLOGIES

At my first valve adjustment I found out why my ONEX was down on power. I thought it was sluggish because it was hauling around a 3X guy in the Florida heat and humidity ( 2000 feet density altidude in not unusual here even though we are at 120 agl.

Shortly after posting that I thought the performance was lacking I performed my first valve adjustment/ head torque routine. The engine has always started well and ran smoothly so I had never pulled the valve covers off to inspect the engine.
When I took my valve covers off I was astonished to find 7 of the 8 valve lash lock nuts lying in the bottom of the valve cover. Even more to my amazement was that the valve gap in some cases had vibrated OPEN to the max that the adjuster balls would allow= about 200 thousandths. OMG how was that engine even running. It ran nicely and started well but just seems a bit low on power.

AFter adjusting the valves properly it has noticeably more power on takeoff and my climb rate is, IMHO, quite good. The other day I was at a density altitude of about 2000 feet on takeoff and had a good solid 500 plus fpm climb with full fuel and my big butt in there. SO..........bottom line> I LOVE MY ONEX. I absolutely look forward to flying it, and I fly it often. I do wish it had brakes and a reasonable fuel filling system but........it is a GREAT airplane and I am thrilled with the way it flies, esp the aileron sensitivity. It has plenty of room, even for me, and reminds me a lot of the Cassutt I flew for ten years and, thankfully, it lands at Half the speed of the Cassutt.( I weighed 90 pounds less when I flew the Cassutt).
I will always be grateful for Wes and Gord for helping me find a ONEX project that I could afford. Thanks guys!!!!

Glen Bradley

Hey Glen,

You'll be past the initial frustration of bring up a new airplane soon. Fueling a Onex will always be a little annoying but once you get used to it it's not too bad. I just check with a dipstick and see how much to add and then reference the graduations on the side of the xfer tank and crank in the proper amount.

There are a lot of guys out there who use the mechanical brakes. They will never hold like Clevelands but they can be made to work OK. I had them on my Sonex and they worked fine. All that to say, don't give up on them yet. Once they make their way to the top of your squawk list maybe you can get them working "good enough".

BTW, I'm just back from 1.5 hours of morning flying. This morning I did something I haven't done much. After some Touch & Goes I took it up to 4500 and cruised for about an hour just enjoying the ride. Wish I had a camera this morning, the sunrise was awesome.

All the Best,

Wes