Alternate Roll Hoop configuration

[LJennings]

Has anyone recently applied for chassis homologation with an alternate design rear roll hoop?

How much of a pita was it? Any thing that I should watch out for?

[ghickman]

Has anyone recently applied for chassis homologation with an alternate design rear roll hoop?

How much of a pita was it? Any thing that I should watch out for?

I built my own Formula B with an alternate roll hoop design. I had it homologated a year ago last September.

We did all the design in Solidworks. We had a P.E. sign off the FEA on the roll hoop that it met or exceeded the SCCA "G" Loading requirements. The entire process was actually fairly simple as long as your design is solid.

This cost us around $750 to hire a PE to sign it off. I'm more than likely one of just a few people on this forum that has done this. You're more than welcome to PM or email me for guidance.

Regards
Gary Hickman
FB #76

[rickb99]

..... We had a P.E. sign off the FEA on the roll hoop that it met or exceeded the SCCA "G" Loading requirements. The entire process was actually fairly simple as long as your design is solid.

This cost us around $750 to hire a PE to sign it off. I'm more than likely one of just a few people on this forum that has done this. You're more than welcome to PM or email me for guidance.

Regards
Gary Hickman
FB #76

That is the key. Find a P.E. to do the analysis and sign off that the design meets the load factors.

[EACIII]

I went through this on the Bowman, the SCCA part is easy, the calculation not too bad for any engineer to do with FEA software. Finding a P.E. to sign off on it was the hard part. First one I went to said it met all requirements but would not sign offf on it. He also did consulting work for us when we needed a structrual engineer. "Did" is the word to note there. And he wonders why I will not use him anymore.

Ed

[Steve Demeter]

Everyone, Just remember that when the PE signs off on the design, they are taking liability for anything bad that might happen. Even if the design is good, said PE has no control over the construction and materials used.

Given today's litigious society, they really have to be very very careful.

We build water treatment systems (think for refineries, mines and power plants) and most always we have to have a PE sign off on various things that is l;icensed in the state where it is going. Particularly Californis for seismic calculations. And getting that done can be difficult.

Imagine the fear that strikes in the heart when someone wants you to sign off on a race car roll hoop.

So take it easy on them and ask nice.

[R. Pare]

If a PE is hesitant to sign off, offer him/her an indemnification.

[ghickman]

If a PE is hesitant to sign off, offer him/her an indemnification.

Richard is correct, I had my attorney draft a Hold Harmless Indemnification agreement for the PE that did the sign off. Before I went into looking for a PE I had this drafted up. I would almost expect this to be requested by any PE signing off on something like this.

Gary Hickman

[Art Smith]

what does the request for approval of an alternate roll hoop design submittal package consist of besides the check?

is there a specified calculation or list of calculations with loading conditions provided by the Club that must be submitted or will a signed/stamped written note from a professional engineer that the alternate roll hoop design meets/or exceeds the specified requirements do??

if finite element analysis (FEA) result(s) are required, is there a list of approved software packages??

finding a professional engineer probably wouldn't be the hard part here (even thou I only worked there 3 months while going to school, there's a large number of retired engineers from the Naval Weapons Center), knowing what to ask for to get it approved the first time probably a bigger challenge.

Art
artesmith@earthlink.net

[Wren]

what does the request for approval of an alternate roll hoop design submittal package consist of besides the check?

is there a specified calculation or list of calculations with loading conditions provided by the Club that must be submitted or will a signed/stamped written note from a professional engineer that the alternate roll hoop design meets/or exceeds the specified requirements do??

if finite element analysis (FEA) result(s) are required, is there a list of approved software packages??

finding a professional engineer probably wouldn't be the hard part here (even thou I only worked there 3 months while going to school, there's a large number of retired engineers from the Naval Weapons Center), knowing what to ask for to get it approved the first time probably a bigger challenge.

Art
artesmith@earthlink.net

spelled out pretty clearly in the gcr

F. Exceptions for Formula Cars and Sports Racers
Any roll hoop design which does not comply with the specifications in
9.4.5., will only be considered if it is accompanied by engineering specifications
signed by a registered engineer. No alternate roll hoop will
be considered unless it contains a main hoop having a minimum tubing
size of 1.375” x .080” wall thickness. The roll bar must be capable of
withstanding the following stress loading applied simultaneously to the
top of the roll bar: 1.5 (X) laterally, 5.5 (X) longitudinally in both the
fore and aft directions, and 7.5 (X) vertically, where (X) = the minimum
weight of the car

That hasn't prevented some pretty dangerous stuff from hitting the track

[Art Smith]

spelled out pretty clearly in the gcr

if you were a registered Professional Engineer it might not be as clear; mine doesn't think so. no mention of FEA or calculations or how the applied load is to be reacted in the calculation(s) if required.

did a signed construction drawing constitute the submittal packages that have been approved??

given what I've seen, troll dectection isn't nearly as demanding a calling.............

Art
artesmith@earthlink.net

[Wren]

if you were a registered Professional Engineer it might not be as clear; mine doesn't think so. no mention of FEA or calculations or how the applied load is to be reacted in the calculation(s) if required.

did a signed construction drawing constitute the submittal packages that have been approved??

given what I've seen, troll dectection isn't nearly as demanding a calling.............

Art
artesmith@earthlink.net

No mention of FEA because they don't require it. If you really don't understand what they want, pick up the phone and call Topeka.

You may want to look for a new engineer. No matter how many different ways I read that section of the gcr, I keep coming up with enough information to draw a free body diagram.

As for the last comment...WTF? I'm not sure what troll dectection(sic) is or what it possibly has to do with anything I wrote. Can you explain?

[Art Smith]

[quote=Wren;238874] You may want to look for a new engineer. No matter how many different ways I read that section of the gcr, I keep coming up with enough information to draw a free body diagram. quote]

so you are or are not a registered Professional Engineer ??

have you submitted and/or signed one or more requests for approval of alternate roll hoop design approval or just offering an "opinion" ??

my post was intended for members of the community with applicable and direct experience getting requests for approval of alternate roll hoop design(s) approved.

Art
artesmith@earthlink.net

[Wren]

so you are or are not a registered Professional Engineer ??

have you submitted and/or signed one or more requests for approval of alternate roll hoop design approval or just offering an "opinion" ??

my post was intended for members of the community with applicable and direct experience getting requests for approval of alternate roll hoop design(s) approved.

Art
artesmith@earthlink.net

I am not a PE, it doesn't apply to what I do and is less common for mechanical engineers than for other groups. Fortunately, that doesn't keep me from being able to read the applicable section of the GCR. If you had truly wanted the correct answer in the least time possible, why wouldn't you just pick up the phone and call Topeka?


My first post answered your question, if you only wanted an answer from a PE, please specify next time. Otherwise, how would anyone know?

[Art Smith]

I am not a PE, it doesn't apply to what I do and is less common for mechanical engineers than for other groups. Fortunately, that doesn't keep me from being able to read the applicable section of the GCR. If you had truly wanted the correct answer in the least time possible, why wouldn't you just pick up the phone and call Topeka?


My first post answered your question, if you only wanted an answer from a PE, please specify next time. Otherwise, how would anyone know?

so you're not a PE. lots of people who attended engineering school or even graduated from an accreditted engineering school don't make the time to get licensed for one reason or the other...................

after working with a PE, have you submitted one or more requests for approval of alternate roll hoop design approval or just offering a "helpful opinion" ??

I'm guessing that there's more members of the community with applicable and direct experience getting requests for approval of alternate roll hoop design(s) approved than PE's that have signed designs used in requests. if Johnny Carson was still alive, it might be interesting to see what "Carnack, The Magnificent" thought the question in the envelope was given the provided "answer".

one of my FF frames would benefit from a taller main roll hoop for taller drivers and I'm wondering about the amount of time and effort to get something approved............... I've never done well or had much patience for the game called "fetch a rock"; showing up with everything required and everything done correctly is easier for everyone involved.

Art
artesmith@earthlink.net

[ghickman]

Art and anyone else asking this question. There's already someone on this forum that has experience with this; his name is Billy Wight. His company is here in San Diego and you can look up his profile on apexspeed to get his contact info.

He helped Jerry Freeman get his home built FB Alt. Roll Hoop approved.

All the SCCA cares about is making sure you got the proper structural analysis done and signed by a PE...and of course the $200 they charge for homologation. Modern FEA software makes this pretty painless.

Gary Hickman

[Art Smith]

Gary-

thanks for the recommendation!! Billy Wight is outstanding to work with; he's done the FEA work on my light weight wheel centers.

Art
artesmith@earthlink.net

[ghickman]

Gary-

thanks for the recommendation!! Billy Wight is outstanding to work with; he's done the FEA work on my light weight wheel centers.

Art
artesmith@earthlink.net

Yep, he's a great resource to have. Anyone that's following this thread needs to keep this guys contact info. on file. This guy can flat crank on FEA, he has software that us mortals can't get.

Gary