Steel vs Aluminum

[rnbraud]

Hello All,

 

I am building a Front Hinged Canopy ala Uli Walter's plans, except I am utilizing a different hinge setup.

 

I am attempting to use a set of 4-bar/articulated hinges.

 

So this past weekend, I temporarily installed my 4-bar/articulated/Audi Trunk Hinge assembly into my fuselage with a

mockup of my canopy frame.

 

Dangit, the damn things bind. After looking at them more closely I realized the base is angled by about 8.5 degrees and the

trunk/canopy attachment is also angled. Rats.

 

So I tried another set of hinges off of a VW vehicle. These were better, in that they opened straight up, however, the trunk/canopy

attachment is bent up by about 10-15 degrees. Rats.

 

So, I decided to build my own that operated vertically and mounted at right angles.

 

My scrap wood mockup worked out pretty good.

 

So, now I am contemplating which material to build these things out of since the auto hinges are made of stamped steel.

 

I have some 1/2" plate aluminum I bought for the original Uli J-Hinge and some 1 1/2" aluminum angle also.

 

However, I am wondering if I use this to build this articulated hinge will it be strong enough.

 

For an all aluminum approach, I would utilize 1"x1/2" "links", the aluminum angle for the canopy attachment, and

some 3/16" plate for attaching to the fuse. The hinge points would utilize the same bushing, or slightly larger bolts, as in

Uli's original J-Hinge pivot points.

 

Or, I could pursue an all steel approach.

 

Or, I could pursue steel "links" with aluminum attachments.

 

So, what do you guys think is the best material?

[Larry Wiechman]

So, what do you guys think is the best material?

Google "FORTAL" for material specs.

Check Ebay for "FORTAL 7075".

Fantastic material to work with and great physical properties!

[rnbraud]

Well, I took John Slades advice and took another look at my Audi A80 hinges.

 

Turns out that canting or angling them about 5-10 degrees inward remove the binding I was seeing. However, I still see some movement of the hinges as they are opened. And I still feel varying amounts of stiffness as they are actuated. And I see some flexing of the rear portion of the hing attach plate where I cut off the third bolt attachment hole.

 

So, I decided to re-think the use of these particular hinges.

 

I tried my other set of VW hinges, but they are too long and I can't trim them to fit.

 

So, then I tried to mock up my own multi-link arrangement using straight rectangular links. This didn't work out too well since the spacers resulted in binding and a lot of play in the closed position.

 

So now I have a new Plan A and Plan B. Plan A is to go back to the junkyards and try to find hinges that are installed 90 degrees between the trunk and car. This is still my preferred approach if I can find some that operate this way and are strong enough.

 

Plan B is to work on the standard J hinges.

 

So, since I can't make it to the Junkyards till the weekend, I will work on my J hinges for now as backup.

 

Thanks for all your help.

 

Oh yeah, as to the J-Hinges, now I have another quandry, aluminum vs fiber/carbon material for them. I am leaning towards the aluminum.

[argoldman]

Well, I took John Slades advice and took another look at my Audi A80 hinges.

 

Turns out that canting or angling them about 5-10 degrees inward remove the binding I was seeing. However, I still see some movement of the hinges as they are opened. And I still feel varying amounts of stiffness as they are actuated. And I see some flexing of the rear portion of the hing attach plate where I cut off the third bolt attachment hole.

 

So, I decided to re-think the use of these particular hinges.

 

I tried my other set of VW hinges, but they are too long and I can't trim them to fit.

 

So, then I tried to mock up my own multi-link arrangement using straight rectangular links. This didn't work out too well since the spacers resulted in binding and a lot of play in the closed position.

 

So now I have a new Plan A and Plan B. Plan A is to go back to the junkyards and try to find hinges that are installed 90 degrees between the trunk and car. This is still my preferred approach if I can find some that operate this way and are strong enough.

 

Plan B is to work on the standard J hinges.

 

So, since I can't make it to the Junkyards till the weekend, I will work on my J hinges for now as backup.

 

Thanks for all your help.

 

Oh yeah, as to the J-Hinges, now I have another quandry, aluminum vs fiber/carbon material for them. I am leaning towards the aluminum.

 

RN,

 

One of the problems with the FHC using hinges from the longeron to the canopy is that as the canopy opens, since the forward part of the hinge is narrower than where it is attached to the canopy, the angle between the two fixed points changes and must be accommodated in the hinge mechanism.

 

The same is true with the gas springs but that is usually taken care of by the ball and socket arrangements on each end.

 

The C hinges solve this in that the two ends don't change angles as the canopy opens. This problem is not noticed with a trunk hinge located in the middle of the front of the canopy for the same reason.

 

If you go to the C hinges, make a fixture to keep the hinge pins parallel and in the same plane or you will get binding left against right.