6 replies to this topic

[Bonde]

Although reluctant to start a new thread due to risk of excessive overlap with existing threads, a search of the forum and the recent exchanges in the thread about single mirrors on Indy cars in the 1970s does to me seem to indicate that a thread dedicated to the car designs of Bob Riley is in fact warranted as pete3664 suggested - many of Bob Riley's designs were unique, iconic and successful enough to merit a thread of its own.

 

I have to begin by admitting I haven't yet acquired Bob Riley's The Art of Race Car Design - I will now have to do so.

 

Being a bit of an anorak, I couldn't really decide whether to start a thread on 1970s single seaters with very shallow monocoques, but I suppose this thread will probably encounter some of those, even if not designed by Bob Riley.

 

Not having read his book, I am admittedly starting on the basis of ignorance, so here goes: Was the 1977 Bignotti Texaco Star Wildcat being shown under construction in Ron Fournier's Metal Fabricator's Handbook built entirely to a design by Bob Riley? The reason I ask is that apparently the formed panels in the tub (my guess the flanged, curved side panels) were made in 6061-T4 aluminium alloy, so I was wondering whether they were heat-treated (artificially aged) to the stronger T62 condition (yield about 40ksi) after forming or were they left in the rather soft and weak T4 condition (yield about 21ksi)?   

[pete3664]

I can't answer for the Wildcat, but can for the 74 Riley that no they weren't re-heat treated, I'll find out next week what alloy was used.  I have photos of the original 74 Riley sides, flanged, curved side panels that show many cuts in the flanges to allow the curve, with an awful lot of rivets.  The inner cockpit pieces are straight and are probably stronger.

[Bonde]

Thanks, Pete

 

In Fournier's book he does mention that the flat panels of the Wildcat tub are 6061-T6. Does the 74 Riley have a folded central main channel (i.e. cockpit inner walls and floor in one piece), or does it have separate floor and wall panels?

 

If one makes bend relief cut-outs on curved flanges folded with a larger bend radius than that possible in 6061-T4, then it is possible to use 6061-T6 for the curved panels as well - I wonder if that's the case on the 74 Riley?

 

Still in anoraksia mode: Some of the 'coke bottle' cars of the early seventies  had wheeled compound curvature panels probably in rather soft, in some cases weldable, alloy (e.g. GM1 F5000) - I don't think any of those were heat treated to higher strength after forming, but probably relied on shape and cold working for strength.

[D-Type]

Were the builders looking for strength or for stiffness?  I suspect they were really looking for stiffness.

[Allen Brown]

Get the book. It has to be taken with a pinch of salt, as Riley is not overburdened with modesty, but worth reading.

[Bonde]

D-Type,

 

It is true that the stiffness (Young's Modulus) is pretty much identical for 'soft' and hardened aluminium alloys, so if stiffness is the primary criterion, then the softer condition will be just as good as the hardened one, but it will only have about half the tensile strength if comparing 6061-T4 with 6061-T6. In my line of work (aerospace) we will never specify a 6061 part in final T4 temper, but 1970s racers might have prioritized differently  

 

 

Allen,

 

I'll just have to get the book now, won't I?

 

I suppose modesty isn't in great demand and supply with people with long and generally successful careers in motor racing, but I'm sure that there must be genuinely modest yet succesful characters out there...   

[E1pix]

Per your last sentence Bondi I sure think there are, in all facets of racing.