In reply to alfadriver :
Because it was brought up earlier as a suggested "sub class".
Carry on...
In reply to alfadriver :
Because it was brought up earlier as a suggested "sub class".
Carry on...
I think we broke the Challenge Money in the O P. I want to see where this Goes
My comment on the challenge class was born of looking at my f500 and really realizing that it is that dirt simple that someone, free of rules, could build similar but faster within challenge budget.
I hadn't thought about limitations with nhra rules.
I am basically advocating for a sub class free of the "production car" rule.
Be careful with safety rules to avoid a deathtrap and it could be an absolutely awesome class with killer innovation. Cheap ass formula one!
I'm partially enamored because new vehicles are getting so complex to mod that I think the longer term future of racing involves more groups moving away from production cars to purpose built.
Here's another idea, assuming you have a source for the big tubes cheaply:
You could use carbon or aluminum tubes, then all of your complex work/machining is in the bulkheads and connectors.
SVreX said: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.
and later he said:
Yep. That's why they call it "The Challenge".
but they don't call it "the Wiki challenge".
and this is why i don't post questions (and rarely post responses) anymore. keep the grey areas grey, and be creative. the rules *used to* require "basic street equipment" but they don't anymore. therefore, the organizers of the challenge have devalued the "street legal" part of the definition you've quoted. and because i know you'll not accept that as a final answer, i will offer the question "street legal *where*" because many areas allow golf carts to be driven on public roads, many areas allow quads to be registered for street use, etc. IIRC, and of course i do, the "street legal" part of the rule was dropped because of the many local variations of what is "street legal." we both have voices. neither of us have *The* voice.
In reply to SVreX :
The rule is that anything the GRM Staff approves is legal - such as the Legends car chassis with the Subaru micro van body. If someone can make the case for this innovative car to the staff, then it's legal.
I wonder if the way to do an inexpensive cut and fold chassis would be to somehow acquire a big preexisting panel of the stuff, then cut/fold/trim/bond as needed. Where would one get such a thing? Is there such a thing as an aircraft pick 'n pull? High performance boat hulls? Balsa core Corvette floors?
In reply to ¯\_(ツ)_/¯ :
There are aircraft salvage yards. You would need to find one that deals with large aircraft to get the passenger deck floor or cargo floor sections. Most of the ones that deal with those sorts of aircraft are out west.
Raw panels can be purchased, but not cheap.
I think it was mentioned earlier, but build ing the components (faces and honeycomb/foam/balsa) separately and then bonding them together to get the panel is fairly DIYable.
Another option for sourcing material might be boat yards... I think some of these panels are used in interior construction?
edit: and depending on the design... since you’re routing and folding, working with smaller panels / off-cuts might not be an issue, since you already need to bond them in halves, etc
In reply to stafford1500 :
I absolutely love the idea of hauling a stack of sawzalled out aircraft floor segments across the country and cranking out a small run of formula racers made from them.
Titan4 said:In reply to SVreX :
The rule is that anything the GRM Staff approves is legal - such as the Legends car chassis with the Subaru micro van body. If someone can make the case for this innovative car to the staff, then it's legal.
Well, that's not a true statement, but whatever....
Sorry if that seems to have caused some butt-hurt. I was a judge that year. FWIW, it was a topic of discussion among the judges. We considered deducting a lot of points because it may have been outside the rules. We (judges) reviewed the rules, and found it to be completely in keeping with the rules for that year.
That car has a VIN number and a production body. It meets the rules.
As Angry has pointed out, there are some big loopholes in the rules. Enjoy them!
Everyone, respectfully... needs to chill out.
If this becomes a challenge rules arcanum fight, I’m going to start deleting comments.
(edited from original)
In reply to sleepyhead :
Thank you. Let's get back on materials. :)
¯\_(ツ)_/¯ said:I wonder if the way to do an inexpensive cut and fold chassis would be to somehow acquire a big preexisting panel of the stuff, then cut/fold/trim/bond as needed. Where would one get such a thing? Is there such a thing as an aircraft pick 'n pull? High performance boat hulls? Balsa core Corvette floors?
I can just imagine the build thread now: "I just popped over to my local pick-n-pull to grab chassis bits for my homebuilt F1 car. Figure I'll be into about $5k when I'm done. It'll only pull 3 Gs in a turn but I'm on a budget 
"
An 8 x 10 sheet should be adaquite, But this is critical, what thickness overall and How thick are the 'Skin pieces" and to what hardness are they to be.
I don't see using Carbon Fiber, to many unknown's about Did I do it Right for me,
I have some great Ideas on Increasing Side Impact stregnth and may reduce the need for a Back bone in the floor to reduce Flex In Tension but torsional twist is hopefully addressed some and even with the Monocoque design they do twist, the wider the more resistant
Front and rear Structures Could be made of sheet but really using Aircraft tech. is simple and well designed tubular Structure iF Higher end Aluminum tubing was used it could reduce weight but raise repair cost.
So what's the cheapest sheet that will work? Can you build it with Alumilite? That's $100 or less for a 4x8 sheet.
In reply to GTXVette :
Need someone with some good CAD skills. That, and some testing of the construction techniques to understand the strength of the panels plus bonding.
I know many race cars in the era prior to fully cured CF tubs were mostly aluminum honeycomb panels. And the strength of that rivet technique is mostly known.
One question is how much is enough? For instance, the ultimate failure and crush strength requirement is very different for an Indycar going around a track at 230mph with concrete barriers vs. a Formula Ford doing whatever at Road America vs. a AM car at an autocross.
I'm beginning to think I need to get some appliance or bicycle boxes and a utility knife then start making templates for some cheap plywood I have in my garage...
stroker said:I'm beginning to think I need to get some appliance or bicycle boxes and a utility knife then start making templates for some cheap plywood I have in my garage...
You have no idea how much we are the same on this.
mazdeuce - Seth said:So what's the cheapest sheet that will work? Can you build it with Alumilite? That's $100 or less for a 4x8 sheet.
I bet you get 90% there with alumilite. But 90% isn't gonna win vs carbon tubs.
I, however, would be really interested to see what could be built with alumilite and a day on a rented cad machine.
In reply to Robbie :
<fistbump>
This thread is right up my alley.
Let's see if I can contribute with some GRM appropriate supplies:
https://www.plascore.com/honeycomb/honeycomb-panels/
https://www.rockwestcomposites.com/plates-panels-angles/sandwich-panels
https://dragonplate.com/carbon-fiber-products
https://dragonplate.com/carbon-fiber-sheets-with-core
https://dragonplate.com/structural-carbon-fiber-components
https://dragonplate.com/flame-retardant-carbon-fiber
https://dragonplate.com/high-temperature-carbon-fiber
http://www.protechcomposites.com/sandwich-panels/
And how about some GRM appropriate CNC routers?
https://www.v1engineering.com/lowrider-cnc/
https://www.makermadecnc.com/product/full-price-pre-order-with-sample-projects-february-ship/
https://www.stepcraft.us/dseries
https://openbuildspartstore.com/machine-bundles/
https://openbuildspartstore.com/blackbox-motion-control-system/
https://openbuildspartstore.com/brands/Xtension.html
https://www.inventables.com/technologies/x-carve/fully-loaded
https://carbide3d.com/shapeoko/
https://www.zenbotcnc.com/4896-4x8-cnc-router_p_34.html
I included a selection of low-price, DIY, kits and even pre-built units. All of which can handle honeycomb/foam/sandwich panels.
The cutting forces involved are very low with these kinds of panels. A handheld router used manually with a fence rips through them like a hot knife through butter. I strongly suggest a respirator, not the stupid paper masks. Carbon/fiberglass/aluminum/nomex dust and shards are murder on your lungs.
Robbie said:mazdeuce - Seth said:So what's the cheapest sheet that will work? Can you build it with Alumilite? That's $100 or less for a 4x8 sheet.
I bet you get 90% there with alumilite. But 90% isn't gonna win vs carbon tubs.
I, however, would be really interested to see what could be built with alumilite and a day on a rented cad machine.
Just to be clear... y'all are talking about Aluma-Lite? because "alumilite" is taking me to some mold/cast making product
this is an example of what I was thinking. Commonly used for business signs. probably in stock at your local print shop.
https://www.laminatorsinc.com/sign-panels/products/alumalite
sorry for the poor spelling!
All of the Alumalite I can find is extremely thin- both at the core and the inner and outer sheet faces. 1/4" of honeycomb with .016" Aluminum on both sides is probably not up to what we're asking for in a chassis.
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