SonexBuilders.net

Folks,

Obviously, I've finally pulled the trigger on my fuselage kit and am continuing with my OneX build. Part of my delay has been analysis paralysis, part of it has been expectations management, and part of it has been "life". It's the right time in life again, I think I have my expectations properly tempered, but there's still a lot of unknown questions I have on "nice to haves" vs. "worth the effort". Hoping a few folks who have been there & done that can weigh in with food for thought.

Let's start with landing gear: I'm based on a 2100 ft. turf field. I think I've picked up that the factory wheels & tires are especially small, and there seems to be a number of folks who have had their factory wheel pants involuntarily removed on turf fields. My desire would be to go to 500-5 tires and Vans RV wheel pants. I think I've seen where a couple others may have done this. Is this documented or laid out somewhere I could read up on more?

Brakes: consensus seems to be that the factory hydraulic brakes are sufficient, but I'm guessing that won't plug & play with someone else's wheels to correspond with the 500-5 tires. Thinking about using a system from Black Max brakes. Anyone else use these that can comment these systems? Thoughts on locating the brake lever on the stick vs. the fuselage side? I plan to build a taildragger and would like to be able to hold brake pressure, control the stick, and run up the throttle for run-ups, so a stick mounted lever seems to be a good solution, but I'm open to other thoughts.

Order of assembly - for the sake of systems installation, does it really matter if I go for wings next vs. finishing kit next? Obviously, it would be a lot more convenient if it was sitting on the landing gear when working on the center wing section. Is there enough work to actually "do" on the finishing kit so I can stay "busy" while I squirrel away wing kit fun money? Also, seems like everyone has to do some clearance operations for the elevator push rod and rudder cables. Should I leave the turtle deck in clecos until all the controls installed, or just deal with the tight space as and when the time comes. I don't have huge hands, for whatever that's worth.

Engines: yeah, yeah...Pandora's box. My thoughts are either (1) Hummel 85 hp. Right price, better alternator, actual magnetos, and a real carburetor. Seems perfect. Or (2), either of the UL Power 4 banger engines are hugely tempting for all the obvious reasons, except for price and the dependency on electrical power for fuel & ignition systems. My primary requirement is to be able to run on pump gas vs. 100LL. Not sure what Hummel's engine needs for octane or ethanol compatibility. Both UL engines will run on 91 ethanol pump gas which is about the same price as the ethanol-free 87 I run in my Cessna and have been accustomed to budgeting for. My building buddies are building O-360 powered RVs, which they will no doubt leave me in the dust just because they can on a regular basis...so the bigger UL engine is definitely tempting. But, I suspect that their first flights will be 2-3 years after mine, so I can probably stomach being the last person to arrive just fine. After all, you can only log hours, not miles... :)

Avionics/instruments: I've analyzed this ad-naseum and realize this is a hugely personal decision...my only real question is, is there really a combo of quality round dials for VFR that can end up cheaper than a GRT mini or MGL mini that includes altitude, airspeed, compass, G-meter, VSI, and legit engine monitoring? If so, I'd love to hear your thoughts.

I'm sure more will come up along the way. So far, I'm having a ball with the fuselage & thanks all for your advice & input!

Cheers,
Brian

I can at least answer the brake mounting question.

Stick grip vs side mount for the brake - I did the stick grip and am really glad that I did. It is very nice when landing to have full control of the brakes, throttle, and stick all at the same time without having to move your hands. You shouldn't need brakes and throttle at the same time but if things get squirrelly it sure is nice to be able to use either/or without having to think about reaching and finding something. Parking brakes are also super simple with the stick grip. A large rubber band wrapped around the stick and the brake lever works perfectly.

Keith
#554

Keith,

Thanks for the input. Who's system did you use?

I used the Tracy o brien brake system but I bought and installed them before sonex was offering a hydraulic brake option. Im happy with the tob brakes but know others who are just as happy with the sonex brakes.

Keith

I would check this site but if I remember correctly the 500 x 5 tires and tubes will fit the Asuza wheels from the kit. If that's the case then the hyd. brakes from Sonex will fit.

The big tires make a big difference on turf. For brakes I wasn't happy with the drum brakes and installed Great plains brakes early in phase one testing in 2010. They are actually made for the Azuza wheels. I recently swapped from hand lever operated master cylinder to toe brakes and wish I'd done it years ago. I managed to fit the Sonex wheel pants over the larger tires but the brake caliper was exposed. I have since made my own pressure recovery wheel pants.

Engine choice. Go as big as you can fit and or afford. A Jab 3300 Onex should almost be able to keep up with the RVs.

Steve
Sonex 892

The 5.00 x 5 tires will definitely fit the standard Sonex wheels. Have been using them for 5 years. I am using Great Plains brakes, (Installed before Sonex had their own, and was warning all that anything but their mechanical ones would tip a tail dragger on its nose) and by splitting just bottom seam, where it does not show, of stock wheel pants and epoxying in an insert, managed to get them over the larger tires and the brakes. Differential toe brakes may not be needed, except when things suddenly get squirrely with cross wind, then can save the day. Wheel pant clearance from ground can be set when installing them. You mention 91 octane gas same price as ethanol free 87. Get the ethanol free stuff only. the ethanol, aside from its other problems, is used to raise octane, but its effect quickly ages leaving you with much lower octane than you think you have. Best to avoid that stuff.

David A. Sonex TD, CAMit 3300

These are my thoughts on the subjects.

Gear: If you plan on doing any kind of grass flying do the larger tires. Easy as that.

Brakes: I plan on switching to the great plains hyd system with toe brakes soon. I hate the side mounted brake lever. A stick mount would work pretty good I would think but I still plan on doing toe brakes just because I like to be able to tap a brake on one side if needed.

Order: I don't know much about the Onex wing assembly but in general wings are easier to store than the completed fuselage.

Engine: As was said prior, you can never go wrong with the most HP you can afford! I wouldn't mind sticking a UL Power on my Sonex.

Instruments: I have the MGL Xtreme. I really like it. It has everything I need and more. It is really nice to pull the SD card and load up the data to Savvy Analysis and see what was all happening with temps, pressures, speeds, etc. If I was at the point right now I think I would go with the iEfis lite. However if I was to stay with the mini stuff I would prob edge towards the GRT mini right now. Like I said, the data recording has been amazingly valuable during flight testing.

Gee, I just realized there are almost 100 Onex's since my 107. There will soon be two more in my area. My build was done in my half of a two car garage. I completed the fuselage and engine before moving it to the airport. I don't know what's in the finishing kit, I bought the whole thing at once. The wings were last, so I didn't have to store anything to finish. They go pretty fast. You will fit the folding wing spars to the carry through spar before assembling the wings. I have the standard wheels and brakes. Don't do grass. I added a single foot brake, centered between the rudder pedals, for holding the plane while doing a run up. I would do that again. You can install a parking brake position but it will not be enough for 2000 rpm. There are too many things to do with your left hand. The trim knob is easier to use if it is mounted vertical on the carry through spar next to your left leg.. It unclutters the area around the mixture control and eliminates a potential knee knocker. The standard Aerovee does a very good job in the Onex. You won't be far behind the 3300's for 1/3 the cost and less fuel usage. I too flew a 150 for many years, and the Onex approach and landing speeds are so similar that little has changed except cruise speed and a much lighter stick. There won't be five minutes difference in 100 miles. The AeroInjector is a simple, trouble free device, once it's adjusted to your liking. No fuel pump, no carb heat, and in my case, the recommended, no gascolator. Keep up the good work, You will love it.

Thanks for the feedback and input guys. That definitely helps on the wheels and tires.

I emailed Scott at Hummel and he confirmed that engines are set up for premium auto gas, and while up to 10% ethanol was ok, its use is discouraged.

Leaning toward a pair of minis to keep engine parameters always visible without cramping the already tiny screen, or the iEFIS Lite. Sent an inquiry in to MGL with extra questions.

I like the idea of mounting the trim off the panel. I'll definitely look into that when the time comes.