Recent warm weather in northern Illinois has opened up our grass strip. Having been snowed in for six weeks, I have been feeling the urge to get some distance from my shadow. Unfortunately, the apron and taxiways will be soft and soggy for a couple of weeks. And lately my lower back has been complaining about pushing the RV back into the hanger. There have been times that the plane stayed in the hanger because I didn?t want to wrestle with pushing it back in after flying. Enter my new second-best-friend, Ronda the Honda. A custom tow bar allows Ronda to push / pull / steer Wild Blue from hanger to runway, and back, avoiding prop nicks from powering through soft gravel-mush, and eliminating trips to the chiropractor?s office.
The custom towbar was welded from 4130 scraps that were on the rack. It is an asymmetric design in order to maximize the telescopic length while minimizing overall length. The towbar telescopes to make connection to the tug easier. A spring-loaded pin locks the towbar in its maximum length position. An adjustable over-center latch connects the towbar to the castering nose wheel, picking up the existing socket head cap screw heads. A spring-loaded latch secures the pin connection to the tug drawbar without loose pieces. A custom drawbar was bolted to existing holes in the chassis of the tug, adding a handy attach point to the little 4X4.
Given yesterday?s mushy gravel coefficient of rolling resistance, four wheel drive was required to get adequate tractive effort. Pulling the plane (forward) is pretty simple and predictable. Pushing the plane backward is an acquired skill. Farm boys that remember backing a hay wagon into the barn will be able to relate. The short towbar makes the system quite reactive at anything beyond about 15 degrees articulation angle. The second prototype will be about two feet longer to make steering a bit less responsive. It is important to note that jack-knifeing this arrangement can potentially overstress the nose gear caster limiting bolts and the nose gear / engine mount bolt. No easy way to put a ?fuse? in the system without creating more failure modes. Fortunately, the jack-knife positions are not near the useful maneuvering positions, and are easy to avoid. The maximum tractive effort generated by the tug appears to be below levels that would cause damage to landing gear structures. Testing continues?.
It was so good to get back in the air after being snow bound!
The custom towbar was welded from 4130 scraps that were on the rack. It is an asymmetric design in order to maximize the telescopic length while minimizing overall length. The towbar telescopes to make connection to the tug easier. A spring-loaded pin locks the towbar in its maximum length position. An adjustable over-center latch connects the towbar to the castering nose wheel, picking up the existing socket head cap screw heads. A spring-loaded latch secures the pin connection to the tug drawbar without loose pieces. A custom drawbar was bolted to existing holes in the chassis of the tug, adding a handy attach point to the little 4X4.
Given yesterday?s mushy gravel coefficient of rolling resistance, four wheel drive was required to get adequate tractive effort. Pulling the plane (forward) is pretty simple and predictable. Pushing the plane backward is an acquired skill. Farm boys that remember backing a hay wagon into the barn will be able to relate. The short towbar makes the system quite reactive at anything beyond about 15 degrees articulation angle. The second prototype will be about two feet longer to make steering a bit less responsive. It is important to note that jack-knifeing this arrangement can potentially overstress the nose gear caster limiting bolts and the nose gear / engine mount bolt. No easy way to put a ?fuse? in the system without creating more failure modes. Fortunately, the jack-knife positions are not near the useful maneuvering positions, and are easy to avoid. The maximum tractive effort generated by the tug appears to be below levels that would cause damage to landing gear structures. Testing continues?.
It was so good to get back in the air after being snow bound!
