McLaren BRM M5a

[datto]

This will be my second time carving a car body pattern, and the first time with an open wheeled car


Bruce Mclaren's one-off M5a, powered by a BRM V-12 engine. I'e found some good side elevations, but dead-on front, rear, and top are proving elusive so
there may be some extrapolation involved. I see some of you gents are already at it with chisels and files. I'll need a bit more info before I start.



I think I have some basswood somewhere. That's a bit soft, but should work quickly if I don't get overly aggressive. The motor/transaxle will be done in the 'puter and printed, I think, and I have a Bruce McLaren ready to go.

[datto]

Revisions, additions.

[tomato007]

Hello Datto,
I like your way to generate a plan for carving first. This will help a lot to avoid mistakes.
Best regards,
The

[datto]

Thanks Tom. I hope the drawings are reasonably (well., accurate isn't the word...0 representative?

I transferred the drawing onto a piece of basswood today and made the first cut.

[Chris Wright]

Marc I hope this helps.




"Another F1 one-off, but purpose built for a BRM V-12 in full 3-litre capacity. The chassis followed M4 lines but the main fuel tanks were within the side pontoons so there were no extemporary bulges (additional fuel was carried above and below the driver's legs and the extensions from the monocoque that supported the V-12). Suspension followed existing lines. This car was competitive - McLaren challenged for the lead in the Candian and Italian GPs with it in 1967, but it was placed in the points only once, when Hulme was fifth in the 1968 South African GP. After that it was sold to Jo Bonnier who raced it late in 1968, and was sixth in the Italian GP. " From: 'A - Z of Formula Racing Cars 1945-1990' by David Hodges

Specifications: Chassis: Aluminium alloy panelled monocoque formed over mild steel bulkheads with long pontoons at the rear to support the V-12 engine
Suspension: Single top link with radius arm, lower wishbone, anti-roll bar and outboard coil spring/shock units in front, and outboard coil spring/shock units at rear. McLaren cast magnesium wheels, 13 x 8½ fronts and 15 x 12 rear.
Brakes: Lockheed discs and calipers all around.
Body: Formed by monocoque sides apart from fibreglass nose cone and cockpit surround.
Engine: 3 litre BRM V-12 with Borg & Beck clutch and Hewland DG 5 speed transaxle.
Dimensions: Wheelbase 96 inches, front track 58 inches, rear track 58 inches.

[datto]

I looked all over for a top view but came up empty. Thanks, Chris, this is very informative..... and back to the drawing board.

[old23]

Amazing! Chris, where do you find these blueprints? One quibble... I believe the plan details a wheelbase of 95 inches, not 96.

Stewart

[datto]

The blueprint drawing is interesting, but puzzling

If we scale it to a wheelbase of 96 inches the LOA is much shorter than the prototype scaling up to 3808mm as opposed to the prototype LOA of 4115mm
If the wheelbase is scaled to 95 inches as opposed to 96, it's even shorter (But the Bruce McLaren website puts the wheelbase at 96 in.

It's still very useful, so thanks again!

[Phil Kalbfell]

I have noted variations on drawings of LOA and believe it depends on where the measurement is taken, it appears that some drawings take into account the exhausts and some do not.
I usually try to find a known factor and scale up or down from that. Tyre or wheel diameter, length of intake manifold etc.
Chris must have a fantastic collection of F1 plans and drawings, can usually find most cars.

[Andrew Rowland]

LOA dimensions as well as heights are as has been pointed out above extremelly variable. When drawing the Policar models I have found that almost no published dimensions are correct and I have therefore completely disregarded them. Nose cowls in particular varied from race to race and this affects LOA.

Cheers
Andi

[datto]

Feb 9, 2017 2:59:43 GMT -5 Andrew Rowland said:

LOA dimensions as well as heights are as has been pointed out above extremelly variable. When drawing the Policar models I have found that almost no published dimensions are correct and I have therefore completely disregarded them. Nose cowls in particular varied from race to race and this affects LOA.

Cheers
Andi

Certainly seems to be the case. So it's down to photo interpretation.

[datto]

Made some changes to the top view, and took the plunge.




Main shapes smoothed out a bit. Poor light for the photo, sorry. The V-12 and transaxle will be done in the computer

[f143]

Lovely basic shape Marc.
Regards
Nigel

[David Mitcham]

Looking very good Marc. Captures the look of the real thing very well.

Best Regards

David

[datto]

Thanks guys!
Got the wood pretty much sealed. On to some detailing.