Help me design a tow dolly

[Richard]

I'm looking for a project and I thought a tow dolly would do it and fill a need I have. Let's start with the requirements:

-dolly weight +/- 30 lbs
-minimum cost
-minimum moving parts
-capable of rolling over max ht 2" metal track for hanger door
-handle max 2,500 lbs on 2% grade
-connects to Scott 3200 tailwheel
-connects to Piper or Cessna nose wheel
-sufficient traction on painted smooth concrete, gravel (compacted decomposed granite) and PSP
-drive motor can be gas or electric
-one speed forward
-speed control w/i easy reach of operator
-swivel min 30 degrees per side
-reversable handle extension to facilitate pull out/push back into hanger


I'm cheap enough to dislike spending $900+ for a lightweight tow dolly. Besides, I know I could build a model at least as good as advertised models. Do I really need a reverse for this size of a/c? What moter/engine should I use? How would you design the swivel mechanism?

 

[gismo]

I'm looking for a project and I thought a tow dolly would do it and fill a need I have. Let's start with the requirements:

-dolly weight +/- 30 lbs
-minimum cost
-minimum moving parts
-capable of rolling over max ht 2" metal track for hanger door
-handle max 2,500 lbs on 2% grade
-connects to Scott 3200 tailwheel
-connects to Piper or Cessna nose wheel
-sufficient traction on painted smooth concrete, gravel (compacted decomposed granite) and PSP
-drive motor can be gas or electric
-one speed forward
-speed control w/i easy reach of operator
-swivel min 30 degrees per side
-reversable handle extension to facilitate pull out/push back into hanger


I'm cheap enough to dislike spending $900+ for a lightweight tow dolly. Besides, I know I could build a model at least as good as advertised models. Do I really need a reverse for this size of a/c? What moter/engine should I use? How would you design the swivel mechanism?

About the only way you'd make the 30 lb budget would be to use an electric motor plugged into 120 v. There are a couple lightweight units that drive the attached wheel of the plane although I don't think this would work well on a tailwheel. As to the swivel question, only the really big tugs use any articulation between the tug and the wheel on the plane.

 

[Graueradler]

Not what youy speced but for getting it into the hangar a boat trailer winch mounted to the back wall might do it. Wont work in the other direction though.

 

[Tom-D]

An electric boat winch bolted to the floor in the rear of the hangar, attached to an auto battery which is charged by a 10 amp trickel charger.

Several of the hangars I have access to have this arrangement, works great.

 

[Dave Krall CFII]

An electric boat winch bolted to the floor in the rear of the hangar, attached to an auto battery which is charged by a 10 amp trickel charger.

Several of the hangars I have access to have this arrangement, works great.

Couldn't you tap a small bolt down into the tarmac (or sleeve to accept a slide-in hand removable bolt) in front of your hangar with a D ring to accept a small block for the pull out cable ?

More towards your specs: The smallest rototiller, stripped down with a receptacle for your attach point.

 

[Richard]

C'mon, if you don't start performing I'm gonna' fire the lot of you.

I recall Mark Schilling wrote on the old AOPA board about a powered winch with bridle that attaches to each main gear. I'm not certain how that would work.

I have a problem with the Stinson. It's a fairly tight fit in the hanger on one side. One guy could push it out but it would be likely to clip the wing on the hanger wall (especially as the mains roll over the raised metal track for the sliding hanger door; if the mains don't hit the track exactly simultaneously the plane will pivot to one side causing the wing to hit the hanger) without another guy watching. Which means I can't fly unless I can round up another person at a usually deserted area of the aprt.

I like the drive wheel on the aircraft wheel and maybe I could figure out how to modify that to tailwheel but I don't understand how I could control the direction without a swivel action. Would I just horse it around to get the direction I want? As you probably can tell my experience so far has been limited to hand tow bars.

Okay, c'mon back y'all. I'll double your pay plus benefits. I need your help to finish this job. Please.

 

[wsuffa]

Richard,

Sounds like what you really need a way to keep from banging the walls. Any of the dollies run the risk of a misguided move.

Why not install 2x4s on the floor of the hangar, forming a track the wheels can ride in? That will make it easy to guide, and you'll have a range of options.

 

[Richard]

Richard,

Sounds like what you really need a way to keep from banging the walls. Any of the dollies run the risk of a misguided move.

Why not install 2x4s on the floor of the hangar, forming a track the wheels can ride in? That will make it easy to guide, and you'll have a range of options.

I like that idea! But it doesn't answer the question of where to push/pull on the a/c. In the past guys have been manhandling the front of the vert stab and it shows. Also, I want to get away from the asymetric thrust of pushing on a wing strut.

 

[Michael]

how bout a bigger plane to tow the smaller one?

 

[Tom-D]

I like that idea! But it doesn't answer the question of where to push/pull on the a/c. In the past guys have been manhandling the front of the vert stab and it shows. Also, I want to get away from the asymetric thrust of pushing on a wing strut.

There are towbars that attach to the tailwheel, these allow you to steer, and push/pull the aircraft with the towbar.

Unless you have handles do not push or pull the 108 by the vert/horizontal stabs.

The Fairchild has about a foot on each wing tip to clear the hangar walls. I painted a location mark on the hangar floor for each main. if it isn't on the mark don't try to haul it in.

Bringing the aircraft into the hangar with a hangar winch. This explanation is for the aircraft approaching the hangar with the left wing tip nearest the hangar.

I paint a strip outward from the hangar where the left main should stop/travel into the hangar. When I taxi up to the hangar with the wing tip 4-6 feet from the hangar door I stop on the line, and shut down. and set left break.

I get out, open the hangar doors, and get my tow bar for the tail wheel attached. Then swing the tail toward the doors and center it on the mark which indicates the centerline of the hangar.

Then I attach the winch cable to the towbar take up the slack, and reliece the left break. Then I can stand next to the winch and start it pulling while I watch both wing tips and tow bar. being sure the tail wheel stays on the center line mark, and both mains stay on thier marks.