Folded Honeycomb Construction - FSAE/GRM Constructions

In reply to sleepyhead :

We actually used to use a single layer of fiberglass anywhere the CF had to interface with aluminum for corrosion reasons.

this thread is awesome. And yes, anyone interested in this should read the chapter in "how to build motorcycle engined race cars". I have the book and I remember the chapter being a quick read but with lots of good how-to including types of joints, adhesive selection, bends vs folds, mounting suspension, etc. I think it mostly talks about aluminum honeycomb sheets, but similar principles would apply to any sheet good with a significant thickness. 

stroker said:

stafford1500 said:

In reply to stroker :

Some of the chassis I have worked on used billet/fabricated pocket inserts for the suspension pickup points. Basically, the bolt receiver is a machined part that get bonded/bolted/riveted into a hole in the honeycomb chassis tub walls. That allows the pickups to be replaced/repaired is there is damage that does not tear the pickup completely out of the tub.

I think I understand what you're describing but pictures would be very useful.

referencing the picture above: The upper a-arms attach at external bolt on pivots at the threaded bungs in the tub, while the lower a-arms attach at pivots inset in the tub (the bolts get put in from inside the footbox). The pockets in the lower section of this tub are bonded in, but allow the lowers to be shimmed up or down separately front/rear to adjust geometry. Similarly the uppers have some adjustability in location witnessed by the multiple bolt holes. All of these are reinforced on the inside of the tub to help spread the loads, along with bulkheads located to help further spread the loads.

stafford1500 with the mic drop

That was a swift answer...

Another, sort of similar but simpler thing- this section of the rail type chassis has threaded backing plates in the top and bottom of the rail, which we bolted the suspension arms to.  They also have big plates so it's clamping a large area of carbon.  The coilover mount is a machined piece of aluminum u-channel, which is through-bolted to the side of the rail (phenolic inside the chassis) and bonded to the outside.

Apexcarver said:

I get that it's absolutely unfair to those building a sedan, but tow cool to see in its own right.

This I disagree with. 

A car like this could conceivably dominate the autoX, but it would suck at drag racing (and might not make it through tech). It’s even conceivable that the Concors score would be compromised.

The Challenge is more than just the autocross.  

With the budget constraints, and the rules as they currently exist for both the drags and the Concors, I think a full-on race build like this would have a hard time winning the $2000 Challenge.  I would welcome them  

To word it more simply...

I don’t think an FASE car or a shifter kart would have beaten any of Mr. Nelson’s creations in the last few years to win the $20XX Challenge overall.

When I was a kid, my dad would take me to the Experimental Aircraft Association Fly-In at Oshkosh, WI.   The EAA would have workshops on various subjects like How to Build a Corvair Aircraft Engine or other types aircraft construction during that week and would frequently have a complete airplane built over the course of the event.  I know the GRM staff are maxed out doing the Challenge but I want to throw this out for consideration: could GRM extend an invitation to an appropriately skilled expert/s to conduct similar seminars/workshops at The Challenge on construction techniques?  A welding seminar would probably be too elementary (with the possible exception of TiG) but something like How to Rivet Aluminum or perhaps Carbon Fiber 101 might be an effective way of disseminating useful construction techniques to The Hive at a nominal cost to the participants.   Any thoughts on that?

¯\_(ツ)_/¯ said:

Another, sort of similar but simpler thing- this section of the rail type chassis has threaded backing plates in the top and bottom of the rail, which we bolted the suspension arms to.  They also have big plates so it's clamping a large area of carbon.  The coilover mount is a machined piece of aluminum u-channel, which is through-bolted to the side of the rail (phenolic inside the chassis) and bonded to the outside.

I think I would need to see the inside of the tub to fully understand what you just said...  Like I said, this is unfamiliar territory for me.

In reply to SVreX :

An unrestricted and regeared (just a chain and sprocket away!) 600cc FSAE car with flat shifting and appropriately sized drag tires should run on par with the sportbike it took that engine from.  That would put its' 1/4-mile time in the mid to high 10s.

Couldn't do it within the budget, most likely, but I think it would be faster than you think with a little development.

In reply to stroker :

If I can track down pictures of the build process I will post them, we weren't big on documenting things unfortunately.

¯\_(ツ)_/¯ said:

In reply to SVreX :

An unrestricted and regeared (just a chain and sprocket away!) 600cc FSAE car with flat shifting and appropriately sized drag tires should run on par with the sportbike it took that engine from.  That would put its' 1/4-mile time in the mid to high 10s.

Couldn't do it within the budget, most likely, but I think it would be faster than you think with a little development.

yes, but it will also likely get creamed by NHRA rules at those speeds. I think my fiat will be rules-limited to 13.5. (let's see if I can even go that fast first!)

stroker said:

When I was a kid, my dad would take me to the Experimental Aircraft Association Fly-In at Oshkosh, WI.   The EAA would have workshops on various subjects like How to Build a Corvair Aircraft Engine or other types aircraft construction during that week and would frequently have a complete airplane built over the course of the event.  I know the GRM staff are maxed out doing the Challenge but I want to throw this out for consideration: could GRM extend an invitation to an appropriately skilled expert/s to conduct similar seminars/workshops at The Challenge on construction techniques?  A welding seminar would probably be too elementary (with the possible exception of TiG) but something like How to Rivet Aluminum or perhaps Carbon Fiber 101 might be an effective way of disseminating useful construction techniques to The Hive at a nominal cost to the participants.   Any thoughts on that?

This would be really cool. 

but if you are at the challenge, just walk around the concour on saturday and ask the folks how they did it. They'll tell you!

Here's a terrible picture of a foam rail chassis that doesn't have carbon on it yet.  You can see the inserts for the suspension and rollbar attachments if you look closely:  

stroker said:

alfadriver said:

And if the resulting tub can be strong and stiff enough, then, theoretically, this allows more manufacturers of chassis.  Then it's up to some company to demonstrate that to organizing bodies, and one instantly brings back the "back yard" engineer that most racing series have been missing since CF tubs have become so common.

This makes me wonder if we can come to a consensus on a common design template that might be used (ala Ron Chapman's Locost) as "open source hardware".  We could develop variations to accommodate differing suspension/drivetrains and post or share them.  

To be honest, I wasn't thinking so much of GRM specifically, but more like when many teams made their own chassis for Indycar and whatnot.  While that may never be an option, there are classes where it's still possible for multiple chassis makers, other than the fact that the cost of entry is so high and complex that nobody would even try.  This seems to have the possibility to lower that entry cost and complexity.  If it can reach down to making a Locost, that would be amazing.  

Heck, if it works out, then who has the free Europa car?  This method could be used to make the steel spine subrfame that would likely be stiiffer, stronger, and lighter than the oirignal.  

¯\_(ツ)_/¯ said:

In reply to SVreX :

An unrestricted and regeared (just a chain and sprocket away!) 600cc FSAE car with flat shifting and appropriately sized drag tires should run on par with the sportbike it took that engine from.  That would put its' 1/4-mile time in the mid to high 10s.

Couldn't do it within the budget, most likely, but I think it would be faster than you think with a little development.

Don't forget somebody ran a twin turbo 600cc car around Road America faster than Mark Donohue did with the Turbo Panzer.  I doubt it would take much to put a 1000cc sportbike engine into a FSAE chassis.  That car would have a FAR greater contact patch than would a bike and would put almost all of that horsepower down for the quarter.

¯\_(ツ)_/¯ said:

In reply to SVreX :

An unrestricted and regeared (just a chain and sprocket away!) 600cc FSAE car with flat shifting and appropriately sized drag tires should run on par with the sportbike it took that engine from.  That would put its' 1/4-mile time in the mid to high 10s.

Couldn't do it within the budget, most likely, but I think it would be faster than you think with a little development.

I am not doubting it can be fast.  I am doubting it can win the Challenge.  

It won't make it through NHRA tech, and it MUST be built on a budget.  Current Challenge rules also say it would have to have production framerails.

(Edit:  It won't run 10's.  It will be rules-limited to 13.5.  That means it will have to beat Mr Nelson's car on the autoX by over 3 seconds, assuming they score equally in the Concours)

I say feel free to bring one.  Play by the same rules as the rest of us, and it won't win.  ;-)

In reply to ¯\_(ツ)_/¯ :

I'll go a step further...

If anyone could do it, YOU could.  Consider it a personal challenge, or even a dare!  ;-)

I will pay your entry fee if you win.

Apexcarversaid:

Seriously, grm, you should make a purpose built racecar supplemental challenge class happen, even as a once off. 

BTW, I'm pretty sure the current rules do not exclude this.  As long as you start with either production frame rails (which can be altered), or a production body:

Challenge Rules say:

Eligible Vehicles:
Any four-wheeled, production-based vehicle that was originally sold as a passenger vehicle is allowed. Vehicles must retain production frame rails or equivalent unibodystructures or, if the vehicle uses a tubular frame, must retain the production exterior bodywork. If a tubular frame is used, then modification of exterior bodywork is allowed, provided the end result is substantially similar in general appearance to the original vehicle. If production frame rails or equivalent unibodystructures are retained, then exterior bodywork modification is unlimited, provided no safety rules are violated. Vehicles that don’t fit these requirements or exceed budget may be run for exhibition only at the event chairman’s discretion.

Clarification Added 1/7/2019: Production frame rails or equivalent unibodystructures may be modified to alter a vehicle’s wheelbase.

In reply to SVreX :

Yeah, that pesky budget is the real issue.  Anyone want to FMV a whole bunch of useless carbon fiber and titanium at like $100?  If we do that, waive the "passenger car" thing, and allow say... junior dragster cage rules for NHRA?  I don't know what else something that size would fall under.

SVreX said:

Challenge Rules say:

Eligible Vehicles:
Any four-wheeled, production-based vehicle that was originally sold as a passenger vehicle is allowed.

sounds like any golf cart or side-by-side fits the letter of this rule

In reply to AngryCorvair :

You're good at this, but I think that is pushing too far:

Wiki definition of "production based vehicle":

The characteristics of a production vehicle or production car are mass-produced identical models, offered for sale to the public, and able to be legally driven on public roads (street legal). Legislation and other rules further define the production vehicle within particular countries or uses.

"A" for effort.

¯\_(ツ)_/¯ said:

In reply to SVreX :

Yeah, that pesky budget is the real issue. 

Yep.  That's why they call it "The Challenge".

Uh, why is this being sidetracked by the Challenge?  

Being GRM does not mean just the challenge.  

Can we get this on track for the dreamers who would like to build their own racer?  Or if they want to try a special Locost car?  

Not for a second do I think this would be challenge material.  And I think CF is not allowed in DM or EM.  But it is allowed in many SCCA formula car classes, so if someone had access to a large enough CNC, could this bring back chassis making from the super specialized CF companies?  That's falls within being GRM.