LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently July 23, 2021, 12:19 pm

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 18 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Type 61 Birdcage Frame
PostPosted: May 11, 2009, 9:00 pm 
Offline
Locostering Information Liaison
User avatar

Joined: August 17, 2005, 1:30 am
Posts: 2403
Location: So CALIFORNIA
I have always loved the style of the Type 61 Birdcage spider.
Specifications
http://www.maserati.org.au/gallery/MASE ... _spec.html

With a dry weight of 600kg, rated at 250hp, rated at 285Kph-300Kph top speed it looked like it should be able to beat the Lotus seven on paper. (In fact it did race and beat two lotus 19's....but reliability issues had plagued it.)

The frame was something they called a "tubular Trellis". The design was criticized as being too elaborate having over 200 pieces ranging from 10mm to 15mm tube.
Found at ...
http://www.supercars.net/cars/2404.html


Attachments:
File comment: Scale model of frame and smaller model of car
maserati_rahmen.jpg
maserati_rahmen.jpg [ 112.43 KiB | Viewed 5026 times ]
File comment: Three view bare frame, naked, and side
cmc_maserati 61.jpg
cmc_maserati 61.jpg [ 172.26 KiB | Viewed 5013 times ]
Bare Frame typo 61 frame.jpg
Bare Frame typo 61 frame.jpg [ 42.85 KiB | Viewed 7115 times ]
Top
 Profile  
Reply with quote  
PostPosted: May 11, 2009, 9:48 pm 
Offline
User avatar

Joined: November 7, 2008, 4:48 am
Posts: 1097
Location: snow city - it's wet!
While I like the style of the car, I had always heard that chassis used as an example of how not to build a tube frame. One of the places I read that is the book "The Race Car Chassis" by Forbes Aird.

The book quote is:
"They must be kidding" department: The stupefying complexity of the chassis of the 1960s era Maserati Typo 60/61 is apparent (.. cutaway drawing reference..). Despite the multiplicity of tubes used, careful study reveals assorted redundant tubes and places where some should be but aren't. The performance of the chassis was no great shakes - breakages were common and the subsequent repair a nightmare. (..drawing credit..).

I'm a track junkie at heart so I would have a hard time building a chassis I knew was compromised (from a performance standpoint) before I even started. However if the car were being accurately recreated with that as the goal I think it would be a pretty amazing project.

_________________
.. in the world


Top
 Profile  
Reply with quote  
PostPosted: May 11, 2009, 10:12 pm 
Offline
User avatar

Joined: July 19, 2007, 4:09 pm
Posts: 550
Location: Austin, Tx
Good god that looks like a nightmare of tubes. I really like KISS.

Good looking car tho. And I love the spare hugging gas tank.


Top
 Profile  
Reply with quote  
PostPosted: May 11, 2009, 10:29 pm 
Offline

Joined: September 25, 2007, 9:33 pm
Posts: 134
Location: Cincinnati, Ohio
I talked to a freind of my uncle who is going to try and build one of these useing a toyota supra drive train. He wants to use my build table when he starts it.


Top
 Profile  
Reply with quote  
PostPosted: May 11, 2009, 11:17 pm 
Offline
Locostering Information Liaison
User avatar

Joined: August 17, 2005, 1:30 am
Posts: 2403
Location: So CALIFORNIA
erioshi
I agree with you on many aspects that you posted. I was reading that broken tubes were not uncommon. :shock:

Quote:
The highlight of the Camoradi season came when Stirling Moss and Dan Gurney won the Nurburgring in chassis 2461, despite bad weather and heavy competition from Porsche's 718 RS60, Ferrari's 250 TR59/60 and Aston Martin's DBR1. Moss described it as "my toughest victory ever in sports car racing." He had been soaked in oil at the begining at at the end multiple chassis tubed had broken.⁴

found at
http://www.supercars.net/cars/2404.html

I think a modern day recreation would be amazing. But as you said before the redundancy of tubes and fragility of the frame would have to be addressed. I think the frame would have to be modeled in and stress tested.

The original frame was 200 chro-molly steel 10 mm (3/8ths inch) through 15 mm (37/64th inch) tubes. Though the gauge wasn't listed. The total car weighed in at 1323lbs. I don't think that using the same diameter tubes or even the exact frame design would be advisable. I would love to see a "recreation in the spirit of" the birdcage. Though I do love some of the features of the original. The transmission tunnel, the thin lace like frame visible through the windshield and the symmetrical lines of the frame. (Crazy? Yes, I know but for some reason I like symmetry.)

http://en.wikipedia.org/wiki/Maserati_Birdcage


When they debuted the Type 61 sold for around $11,000 dollars.

Earlier someone posted the picture of the "Dio" a kit car of the birdcage and I almost cried at how ugly it was in comparison.
http://www.kitcars.com/Classifieds/AdDe ... d_id=21525
(Please don't click unless you want to be saddened)


Attachments:
File comment: Cutaway chaos to illustrate point made
m_ouchi_maserati_birdcage.jpeg
m_ouchi_maserati_birdcage.jpeg [ 292.67 KiB | Viewed 5009 times ]

_________________
I'll keep an eye out for you!

To err is human...
I am more human than most.
Top
 Profile  
Reply with quote  
PostPosted: May 11, 2009, 11:33 pm 
Offline
User avatar

Joined: July 19, 2007, 4:09 pm
Posts: 550
Location: Austin, Tx
Sheesh, is that birdcage built around the engine? Looks almost impossible to remove.


Top
 Profile  
Reply with quote  
PostPosted: May 12, 2009, 12:15 am 
Offline

Joined: July 23, 2007, 1:46 am
Posts: 268
Location: Santa Clara, CA
mr.peabody.d wrote:
(In fact it did race and beat two lotus 19's....but reliability issues had plagued it.)


Don't get me wrong, I love the Birdcage. In its day, the Birdcage was indeed a force to be reckoned with and may have even beaten the 19's a few times, but overall, the 19 OWNED the Tipo 61. http://vintageracecar.com/pages/thismon ... magiid=137 :wink:

BTW, I recently hung out with the owner of the Camoradi car. I had no idea he owned it, until we got to talking about cars of the period...

I was actually there to see his "other" car:
Image

_________________
http://www.pbase.com/ninerjoe/lotus_19_build


Top
 Profile  
Reply with quote  
PostPosted: May 12, 2009, 5:05 am 
Offline
Locostering Information Liaison
User avatar

Joined: August 17, 2005, 1:30 am
Posts: 2403
Location: So CALIFORNIA
Lotus19
Loved reading that story about the birdcage cleaner. Great little article About the Lotus 19....
Quote:
It was, therefore, essential that this new car ran trouble-free and was quick straight out of the box

The more I read, the more it seems that anything that ran reliabliy could beat the birdcage half the time, and then even more after that if it was competetive. I don't mean to discard or discount the Lotus 19....sounds like Colin Chapman and Mike Costin were patient and took their time doing it right with the 19.


(apologies to everyone for the 4 pictures I posted /attached are so HUGE!)

_________________
I'll keep an eye out for you!

To err is human...
I am more human than most.


Top
 Profile  
Reply with quote  
PostPosted: May 12, 2009, 10:20 am 
Offline

Joined: July 23, 2007, 1:46 am
Posts: 268
Location: Santa Clara, CA
mr.peabody.d wrote:
Lotus19
I don't mean to discard or discount the Lotus 19....sounds like Colin Chapman and Mike Costin were patient and took their time doing it right with the 19.


I knew you weren't bad-mouthing my 19 8) ... Actually the 19's weren't that reliable either. Their Achilles heel was the infamous "queerbox" that would break with regularity...

Carl, the owner of the Camoradi 'cage, told me he had the car at Pebble Beach a few years ago and had dinner with Moss and Gurney for 2 nights. They were talking about the Maser and the 19. Even though he was very successful with Lotus, I was surprised to learn that Moss wasn't a big fan of Chapman's approach to racing: Whereas Maserati used purpose-built, beautifully machined hardware, Chapman was notorious for using parts of old Austins, MG's, etc. to piece together his cars...

Here's a bit of trivia: After his near-fatal crash in '62, Moss drove his first practice laps in a Lotus 19.

_________________
http://www.pbase.com/ninerjoe/lotus_19_build


Top
 Profile  
Reply with quote  
PostPosted: May 12, 2009, 2:17 pm 
Offline

Joined: August 13, 2008, 10:36 am
Posts: 352
Location: Lynchburg, VA
Birdcage - tiny tubes ["10 mm (3/8ths inch) through 15 mm (37/64th inch) tubes."] - "breakages were common"...

Imagine that. Inevitably, I mean no matter how elegant the design, the very purpose of all those little tubes - rigidity - is the cause of their failure. No give, no spring, no flexibility. Even if the forces are supposed to be distributed among several tubes at once, in reality one tube or weldment will take too much stress, and fatigue. Pow. Then more stress on the next tube...

Too much like building a car with tinkertoys. I am surprised those builders didn't figure this out ahead of time. :shock:


Top
 Profile  
Reply with quote  
PostPosted: May 14, 2009, 2:05 am 
Offline
Locostering Information Liaison
User avatar

Joined: August 17, 2005, 1:30 am
Posts: 2403
Location: So CALIFORNIA
Smiles, I would love to see it modeled in FEA (or similar) to see where the weaknesses really lay and what was redundant. {Love to see a comparison between the Mercedes "Gullwing", Maserati "Birdcage", and a lotus or two.}

I have read varying facts on the internet about the frame... One source claimed they were aluminum tubes, another site steel, and another site cro-molly steel, but no comment about the gauge of the tubes.

The internet is sprinkled with truths, saturated with opinions, and spiked with lies.

_________________
I'll keep an eye out for you!

To err is human...
I am more human than most.


Top
 Profile  
Reply with quote  
PostPosted: May 14, 2009, 10:56 am 
Offline
User avatar

Joined: January 14, 2009, 11:25 pm
Posts: 163
Location: Cleveland, Ohio
I'd like to see an FEA done on it as well.. Thats going to be a tall order though, having to get dimensions by scale, guessing tube materials, cross sections..
I think the Birdcage was well intentioned, but it would have to have certain areas of stress concentrations thru the roof (given that any fea would have been done on paper, yikes!), leading to breakages and accelerated fatigue.

I guess my frame design does look just as guilty, now that I'm looking at both at the same time.. :shock: Back to the drawing board.. 8)


Attachments:
File comment: I know, too many tubes..
frame final1.JPG
frame final1.JPG [ 130.24 KiB | Viewed 5001 times ]

_________________
http://www.spartanv8.com/
Top
 Profile  
Reply with quote  
PostPosted: May 14, 2009, 9:45 pm 
Offline
User avatar

Joined: November 7, 2008, 4:48 am
Posts: 1097
Location: snow city - it's wet!
mr.peabody.d wrote:
I would love to see it modeled in FEA (or similar) to see where the weaknesses really lay and what was redundant. {Love to see a comparison between the Mercedes "Gullwing", Maserati "Birdcage", and a lotus or two.}

From what I've been able to glean, the Mercedes in question used a more conventional spaceframe design to triangulate the passenger area and transfer loads between the cars different sections. That's why the chassis has such high door sills and the gullwing doors were developed. From what I've read those areas of the chassis were better than the Type 60/61, but overall the MB was not exactly perfect either, just very good for it's day.

Based on what I can see above, it looks like one of the largest potential points of failure for the Birdcage might be where loads are passed from the rear suspension "box" to the passenger compartment. It doesn't look like there's much support either laterally or for passing fore/aft loads. But as you said without any real analysis I am pretty much just guessing.

_________________
.. in the world


Last edited by erioshi on May 24, 2009, 10:50 am, edited 1 time in total.

Top
 Profile  
Reply with quote  
PostPosted: May 24, 2009, 8:55 am 
Offline

Joined: March 26, 2006, 6:03 pm
Posts: 216
holy hell! Your right the only sections that handle those loads are not even triangulated.
Attachment:
cmc_maserati 61.jpg
cmc_maserati 61.jpg [ 61.07 KiB | Viewed 4989 times ]


The bars in red plus the floor pan take all the force from the back of the car.... with all that tubing you would think they would throw one or two into that area.


Top
 Profile  
Reply with quote  
PostPosted: May 24, 2009, 11:22 am 
Offline
User avatar

Joined: November 7, 2008, 4:48 am
Posts: 1097
Location: snow city - it's wet!
In one of the model pictures above it looks like the original car may have used a very sturdy firewall across the back portion of the passenger area including the sections you highlighted. Even if that is the case, while that firewall section would help with torsional stiffness, the fore-aft bending load paths through the rear of the passenger area would still be less than ideal.

The reproduced frame below looks to have tried to addressed those areas:
Image

_________________
.. in the world


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 18 posts ]  Go to page 1, 2  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 5 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
POWERED_BY