Onex Project / “Wings and Things”

Finally, wing frames both inboard and outboard are completed along with the folding mechanism and locking pins. Outboard wing skins have been installed and inboard wing skins are fitted and standing by. Time is funny stuff. Some days it feels like you have accomplished nothing at all and yet in the realm of the airplane builder, tiny little baby steps add up to big progress and before you know it major components are sitting around waiting for the final assembly. So it has been with the wing assemblies.

I can’t say we haven’t had our setbacks and headaches with the Onex project. It really is a “simple little airplane” and should probably not require any mountain of knowledge in order to put part “A” into part “B.” Still, we continue to find voids in the plans which leave the builder to scratch his or her head for a few hours; or a day; or two. In my mind this should not be the way builder support works. If there is a problem putting part “A” into part “B” and riveting it in place because part “D” is in the way and must first be removed; I think the builder should be forewarned. Time and again on this “simple little airplane” we are left to wonder which came first the chicken or the egg.

You may notice from the videos that in the sequence of building we have removed the fuselage from the gear and placed it on saw horses. This was done for two reasons. First, there are two rivets on the bottom of each inboard wing skin that simply cannot be installed with the gear in place so the gear had to be removed. The second reason is that there is no way to string the rudder cables without getting into the tail cone. This is very difficult to do while the tail of the fuselage sits low to the ground or if the bottom skin has already been riveted in place. There is little chance (or none) of either Brad or me being able to get into the tail cone from the fuselage, and no notes were located providing any guidance on these two vital things to look out for. If for some reason an ardent builder had riveted the bottom skin to the fuselage, at this point he or she would be faced with the daunting task of running rudder cables to the rear of the airplane with little or no access. The easiest way to remedy this would be to drill out all the bottom skin rivets and pull the bottom skin off again! I have little doubt that this has occurred in more than one case.

Placement of rudder cables also appears to be a builder researched design. We found little or no guidance for the running of these cables other than a brief note advising that some former holes may need to be enlarged to permit cable passage without interference. Ya think? From what we have seen, the holes in the formers are too small and mostly in the wrong position to permit uncompromised run from front to back. In the case of the starboard side of the fuselage the rudder cable is in direct conflict with the elevator actuator rod which, also, has need of much relief of the formers in order to make a clear run aft. Since no pilot I ever met would want the rudder cable sawing away on the elevator actuator push tube, nearly everyone we have observed building one of these “simple little airplanes” has mounted a pulley in this area to provide the needed relief between the two control surface actuators. Of course that necessitates the addition of still more pulleys to keep the cable running unhindered from front to rear. In the end, a pulley was installed at every former station and holes were relieved as needed. It probably shouldn’t have taken two days to do this, but it did.

The entire fuselage has now been lowered to just above the floor so that cockpit work can begin without reaching over the side of the airplane to work inside. Again we find ourselves “re-engineering” some design features of this “simple little airplane.” The fuel tank sits over the knees of the pilot suspended by two mounting straps. The tank is covered with the combing, and the combing is mounted to the two top longerons and instrument panel. Plans call for the combing to be placed over the tank and top edge of the instrument panel and riveted in place. It would seem prudent to me to put nut plates in this location rather than rivets since I am virtually positive that sooner or later someone, somewhere, is going to need to get to either the fuel tank or the back of the instrument panel for something. While we are in the business of nut plates, we are also planning on screwing that bottom skin on to the fuselage because riveting that skin in place means no one, nowhere, is ever going to be able to get into the tail cone to repair whatever might go wrong there.

I understand the need to design an economical and “simple little airplane” for builders to enjoy. What I will never understand is how the design work, or lack thereof, as well as the construction guidance (or lack thereof) for this “simple little airplane” was ever deemed adequate. We’re going to build it anyway!

Visit with us at the “Skunkworks” as we work our way through these and other challenges in “Onex Project /Wings and Things.”

We’re gonna have a great time! (Mostly)

Capt. “T”

 

Tom Speerstra

Author: Tom Speerstra

Tom Speerstra has had an enduring love affair with aviation for over 40 years. Countless adventures have been enjoyed flying students, people, paper, and parcels in everything from Champs to Citations. He has held positions as both Chief Pilot and Director of Operations for Part 135 carriers and holds an ATP, MEII, SES ratings and a Citation type rating. Tom makes his home in Michigan with his wife Elizabeth and Pappy “the dog” Boyington.