Wheel alignment check

[rodsmith]

Before the fuselage was covered I had checked the wheel alignment and both sides needed to be adjusted (plans built fuselage and gear). I think I did it with the wings installed, didn't record the gear spread but think it was about 70". Since then I replaced my streamlined shock struts with the round struts from the factory. The fit wasn't quite as good, I remember it being hard to get the bolts in one side. Before I fly I wanted to verify that the alignment and gear spread was good. I loaded the plane to 2000# using blocks of crack seal for our runway that weigh 33#s each. Saved me from buying sand bags. I rolled the main gear onto grease plates and the center to center wheel distance was 71 5/8th. Added another 3 blocks and the gear spread was right at 72". Toe in was measured as .15 deg on the right and .65 deg on the left. Bob's spec calls for 0 to .5 deg toe in. I called Bob this morning and he said that ideally it should be closer to 0 but shouldn't be a problem. One of his planes has toe in closer to 1 deg and hasn't been an issue. He said if it taxis straight it should be fine. That was great news as I didn't want to cut away fabric and get the torch out. I think this is an important item to check before flying, even with a kit built plane.

DSCF2619.jpg DSCF2623.jpg

[Battson]

Nice remarks and photos Rod. It's not uncommon for the gear to take some fitting to start with, but they soon wear-in nicely, with use.

I think it's worth stating explicitly, for any new readers, that it's possible for the wheel alignment measurement to change depending on the weight in the fuselage and whether you measure in 3-point attitude or level-fuselage attitude. Consideration needs to be given to those factors.

As you can imagine looking at the photos, the alignment in the fuselage-level attitude would be considerably different if the wheels had any camber (in or out). In a real-world situation where the aircraft is landing, the camber is changing constantly as the main landing gear oleos travel in and out. The fuselage attitude can also change a fair bit during a landing sequence. Overall, this means the effective wheel alignment (or "toe") is also changing constantly during a real-world landing.

In my opinion, all that contributes to a situation where pilot inputs are more important than the "precise" toe measurements, especially if the measurements are somewhere near the specified range.

It's also worth saying that, despite the best wheel alignment in the world, pavement landings and especially high-speed taxi testing increase the risk of a directional control incident. It is sensible to avoid those activities until the pilot is fully current in the specific aircraft being flown.