P

pboyce

Active Member
I built and am flying an RV-7A. My father recently sent me an almost complete Glastar to finish. With the Glastar came a lightweight aluminum towbar, feather light. Really really slick.

I am currently using the Bogert towbar for my RV-7A, but that thing is heavy! Made of steel, which is pretty much an abomination to carry in an aluminum airplane. I spoke to Bogert a couple of years ago about making a lightweight towbar for RV owners. He said he would think about it...

Does anyone know of anyone who makes a lightweight aluminum towbar for RV's? This is a product waiting to happen.

Regards,

Paul
 
Hmm, wondering

Is there any markings on the Glastar one? The reason I ask, is that Lancair also sells a very lightweight towbar that is aluminum and colapsable. I wonder if they both use the same Company to make them. I dont have one of the Lancair ones, but if the glastar one fits a bracket like this, then perhaps, if we find out the company, I'm sure there is enough market for them to do an RV version...

Here is what the Lancair version looks like... Dang, they aren't cheap...
http://www.aerocraftparts.com/ItemForm.aspx?item=801-0004

And this is the tow point that it connects to...it's the little raise at the front T mount that bolts right to the top of the bottom collar on the strut to nose fork mount - I didn't have a better picture... Sorry.
DSCN0941.sized.jpg
 
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How timely is this?

pboyce said:
I am currently using the Bogert towbar for my RV-7A, but that thing is heavy! Made of steel, which is pretty much an abomination to carry in an aluminum airplane. Does anyone know of anyone who makes a lightweight aluminum towbar for RV's? This is a product waiting to happen.
Regards,Paul
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Paul,

I guess you missed my recent query in the 6A (Model Specific) category.
http://www.vansairforce.com/community/showthread.php?t=7194
I gladly give Roberta full credit for recommending the Wag-Aero design. Upon her recommendation, I ordered and received it. The Wag-Aero design is everything the Bogi-bar is not. It breaks down for stowage and only cost $45. Unlike the Bogert design which the operator has to be extra careful and proceed gingerly when inserting and more or less depends upon the spring loaded property of steel to secure the legs to the axle bolt, the Wag-Aero sports a true spring between the yoke legs that insure and maintain a constantly even pressure on both sides of the axle bolt. If your experience mirrors mine, on several occasions the Bogert has slipped off the axle bolt and I (or my hangar partner Craig) inadvertently towed Darla by the wheel pant! This ultimately caused a slight but irritatingly noticeable elongation of the axle access hole on the port side of the fiberglass nosewheel pant. It was Craig who complained and Roberta whom ultimately referred me to the vastly superior Wag-Aero towbar design. Thanks again Roberta!

Rick Galati RV-6A "Darla"
 
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Bogert tow-bar upgrade

In defence of the Bogert tow bar...

I had problems with mine. I used the main axle bolt as the attach points originally because the tow bar fit there without modification to the nose wheel pants.

Predictably, I ended up damaging my wheel pants do to the kick back from releasing the spreader bar and from the tow bar slipping off the axle bolt.

I called Rich Bogert and he immediately sent me two fixes: a redesigned speader bar that works much better (about half of the kick back), and new cap screws and special 1/2" bushings/standoffs to replace the forward attach screws on the wheel pant.

The only modification I had to make was to drill out the wheel pant opening for the cap screws to 13/16 for the tow bar to fit.

This makes a huge difference in the security of the tow bar when it's clipped into place. I'm very happy with the result and Rich Bogert's service. Rich called me twice to make sure everything was in order, and he is clearly committed to supporting his product.

I've gone from being somewhat disillusioned to very happy with his product.

He offers this upgrade to anyone who asks.

Sorry, no photos.


Vern Little
 
Rick,

Thanks for the link to the Wag Aero towbar. It appears that towbar is also made of steel.

My point is this: I worked hard to make my plane lightweight. So it hurts to put a steel object, unecessarily heavy, into my airplane.

Also, at the paintshop, the Bogert towbar slipped off the axle and slightly damaged the wheel pant, which seems to be a common experience among owners of this product.

There is obviously a lot of room for improvement in this arena...

Paul
 
tomcostanza said:
Are you telling me you guys built an entire airplane, but can't build a decent tow bar?? :confused: No way!
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This is what I was thinking. I am no genius and basically feel that I have tons to learn in my progress toward completing my airplane. With that being said, I sure hope that when the time comes when I will need a tow bar I will be able to build something that will work for me. We are talking about aluminum here. I have discovered in my building process that it sure is easy to work with. I am thinking that something on the caliber of building a tow bar should be a piece of cake after I finish with the airplane build.

RVBYSDI
Steve
 
I've got an alum. 9hort) hand made one but I still prefer the Bogi and my Wag aero.

Also, I designed my front pant so that the towbar doesn't go into the pant.

My flash reader is messed up so I can't post or download picts or I'd show a pict maybe next week.

edit-- I try to leave my key ring at home when going lite. :)
 
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tomcostanza said:
Are you telling me you guys built an entire airplane, but can't build a decent tow bar?? :confused: No way!
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Interesting.
Without having read past the first post in this thread, that was my exact thought! :)
 
vlittle said:
In defence of the Bogert tow bar...

Sorry, no photos. Vern Little
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Thanks for the mention Vern.
We enjoyed working with you on this project!


Here are a couple of photos.

wheelpant.jpg
Near flush with wheelpant.

04-pinkitRVA.jpg



On the right; what we believe is the most common set up found on most RV#a?s with providing about 3/8? engagement.

On the left, Bogert?s extension kit with just over 1? engagement.

An "extension kit" will help give the Bogi-bar (or any other similar tow bar) more positive contact area resulting in more control when maneuvering tight angles, and a better view of what you are trying to attach the tow bar to with no additional drag.


I am sure some builders will prefer to figure this out in a 'do-it-yourself' fashion, but Bogert Aviation is offering the kit for $15. plus freight for those of you who prefer a hassle free kit.

Cathy Bogert
 
The Bogert upgrade works very well, and has eliminated any tow bar slipping and resulting damage to the wheel pants.

PS, tow bars take a lot of abuse. I can't imagine an Aluminum tow bar working very well over the long term without being bulky and heavy. Same reason the landing gear struts are not aluminum.

Vern Little
 
CathyBogert said:
I am sure some builders will prefer to figure this out in a 'do-it-yourself' fashion, but Bogert Aviation is offering the kit for $15. plus freight for those of you who prefer a hassle free kit. Cathy Bogert
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I did decide to fabricate my own spacers. I first bought some 1-1/4" long screws from the hardware store. Then I ordered a 1/2" OD / 0.370" ID 2024T3 Tubing from ACSpruce (P/N 03-32800). I drilled the ID to 3/8" and cut to length. Cheap and easy.

Here is a picture of this next to the 3/4" screw supplied by Van's.
spacer3yp.jpg
 
Just to give another input. I have the same BogiBar and have never had it slip out. I also don't have extended screws, only a few washers under the stock ones. The key is to drill the hole in the fiberglass the same size as the tow bar outside diameter. This has worked just fine for me over the last 3 years. It clamps in place and holds fine.
2003-10-19_17-05-38.jpg
 
Aluminium

vlittle said:
... PS, tow bars take a lot of abuse. I can't imagine an Aluminum tow bar working very well over the long term without being bulky and heavy. Same reason the landing gear struts are not aluminum.
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Mine are. :)

 
i find the greatest value of a towbar to be-- keeping the nosewheel straight when pushing the plane backwards, while pushing on the prop, close to the hub.

it's dicey if you get sloppy backing into a crowded hangar-- the rear of the plane will swing quickly(huge movement) and hangar rash instantly.
 
Just my 2 cents. I ordered a Wag-Aero tow bar for my 6A and it didn't fit. The Bogert Bogey-Bar works like a champ! (I cried over the price, though.) Maybe each planes pants are different?
 
I'm not sure why this discussion got focused on spacers. And Cathy Bogert, thank you for chiming in.

As for the claim that an aluminum towbar would not last, that was not my experience with the Glastar towbar. It was well made, lightweight, and very sturdy. Please refer to my photo of this towbar.

I'm saying something very simple. A lightweight high-performance airplane deserves a lightweight high-performance towbar. The Bogert towbar, while it works well, is old-school heavy steel. Not something I relish taking on a trip.

If I knew how to weld aluminum, I would. Or maybe I'll try to modify the aluminum towbar made from a modified crutch, a project spelled out in the March 2010 issue of SportAviation.

I would like to finish by asking Cathy Bogert why they can't make an aluminum towbar for RV's? What is holding them back?
 
Steel is actually superior...

...for small diameter, thin wall tubing applications where the design criteria is resisting bending loads, which is what one gets when steering the nose wheel.

Years ago in a former life I manufactured a small trailer for transporting SCCA Formula Fords and Sport Renaults (Sport Real Slows!). The trailer design was a welded, tubular truss frame made of 1 x 1 15g steel tubing. Because of the small dimensions, the tubing's section modulus was low.

The mechanical properties of steel are so much higher than a reasonably priced, weldable aluminum alloy that I would have had to use solid 1" square aluminum bar stock to achieve the same strength and using aluminum would have increased the trailer's weight!

I tried to limit the use of engineering terms in hopes that this post would be useful. Hopefully, the information is helpful. Aluminum weighs 1/3 the steel weight but has proportionetely lower strength. When I was in the auto industry, finished aluminum designs typically weighed 2/3 of the steel part because one had to use twice as much material to achieve similar strength given packaging constraints. The riveted, monocoque construction of airplanes results in large section moduli and does not require welding, hence the ability to use aluminum to great advantage.
 
Larry,

Your analysis makes sense--up to a point.

The fact is, I had an aluminum towbar for my Glastar which worked very well. And the Glastar was harder to nose steer versus my RV-7A. That towbar performed admirably and had more than enough strength for turning. It was very light, maybe half the weight of the Bogert towbar. Please look at the photo which I've attached in a previous reply.
 
Vern's post about the durability of aluminum towbars reminded me of something that nobody has mentioned yet... For nosewheel aircraft, these aren't "towbars" at all. They are "steerbars". Anyone who uses the towbar as the sole means for manoeuvering their airplane on the ground is just asking for a damaged wheelpant. Push and pull the airplane with one hand on the prop near the hub, and use the other hand for steering.

Done this way, it takes almost zero effort to steer once you're moving, and should be extremely low-stress on an aluminum towbar.

Those of us with tailwheel aircraft don't have that luxury unfortunately... But i'm still making mine from an aluminum crutch. At least the first version. :)
 
Rob,

Please keep us posted as to your progress. I've decided I want to make one out of an aluminum crutch as well.

My RV-7A cost me a lot of time and money to build. And as Vans has been emphasizing for the past 30 years--KEEP IT LIGHT! So I've adhered to his philosophy as best as I can. However, the Bogert steel towbar is a fly in the ointment. I only grudgingly take it on trips, since there are no good alternatives. The fact that the Glastar aluminum towbar works so well proves that aluminum is a viable material for an RV towbar.
 
As a steer bar...

... all you're trying to resist is the moment due to negative caster to keep the wheel straight. I agree that the bending load on the drawbar in that case is insignificant. One could also limit the moment in the forward direction by ensuring that the tires were rolling before attempting to change direction. "Dry Park" steering loads are exceeded in automotive steering design only by the "curb pushoff" test.

I am real happy with my Bogi bar because if I had an aluminum version I would probably be dumb enough to give it a "dry park" test. I like the telescoping drawbar because I once made a non-telescoping drawbar for my Cherokee (actually it was so I could use a lawn tractor as a tug) and it was too long to go in the Cherokee's baggage compartment.

My previous remarks were based on an aluminum tow bar with the same features as the Bogi Bar.

Larry

Snowflake said:
Vern's post about the durability of aluminum towbars reminded me of something that nobody has mentioned yet... For nosewheel aircraft, these aren't "towbars" at all. They are "steerbars". Anyone who uses the towbar as the sole means for manoeuvering their airplane on the ground is just asking for a damaged wheelpant. Push and pull the airplane with one hand on the prop near the hub, and use the other hand for steering.

Done this way, it takes almost zero effort to steer once you're moving, and should be extremely low-stress on an aluminum towbar.

Those of us with tailwheel aircraft don't have that luxury unfortunately... But i'm still making mine from an aluminum crutch. At least the first version. :)
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Extended towbolt

Eric's idea looked like a good one, so I purchased two high quality 3/8 x 1 1/4" stainless steel bolts from the local fastener store with 4 nuts. Remember, these are fine thread. The nuts are appx. 3/8" thick. Instead of having to order the associated tubing, I put on the first nut and wrenched it tight against the cap screw head. I then put on the second nut and wrenched it against the first nut. Next I ground the corners off the hex nuts on a bench grinder (while assembled) so that the nuts were now round and the same size as the cap screw head. I polished them up a little with the scotch brite wheel. It's easy to do if you use the allen wrench on the screw head and an appropriate socket on the threaded end to hold the assembly while you grind away. All in all I think this is a bit stronger than a piece of tubing (since it is supported by the threads instead of the screw shoulder) and you don't need to order anything. The stainless solves that rust problem too! Less than $4 of hardware.:)
 
A friend flies a Bonanza and uses that exact towbar and said it came with the plane. He is real happy with it. You might check the Bonanza web site.
 
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