Derby Talk

HEY GUYS:

IT APPEARS THAT A FEW OF YOU HAVE HAD SOME EXEPERIENCE WITH BUILDING AND RACING CUBMOBILES. OUR PACK IS PLANNING ON DOING THIS FOR THE FIRST TIME THIS YEAR. WE WOULD LIKE TO BUILD A CUBMOBILE TO RACE AT OUR DISTRICT RACE WHICH WILL BE HELD MARCH 31. I KNOW THAT'S SORT OF SHORT NOTICE, BUT I HAVE A FEW DADS WHO ARE WILLING TO WORK ON THIS PROJECT BUT NEED SOME DIRECTION AS NONE OF US HAVE ANY IDEA AS TO WHAT A CUBMOBILE EVEN IS!

THERE ARE A FEW GUIDELINES WE HAVE GOTTEN FROM :

CAR MUST BE SOLIDLY CONSTRUCTED OF WOOD, MASONITE, OR METAL, WITH SOLID BOTTOM, SIDES AND FRONT, AND MUST HAVE A STABLE SKIN. PUSH HANDLE MUST BE PERMANENTLY FASTENED TO CAR.

CAR MUST HAVE A SAFE STEERING MECHANISM. IF CABLE DRIVEN, MAKE SURE CABLE IS TIGHT.

SIDES OF COCKPIT MUST EXTEND MINIMUM OF 6" ABOVE SEAT.

FRONT AND BACK ENDS OF CAR MUST BE ENCLOSED.

EACH CAR MUST HAVE 4 WHEELS.

CAR SHOULD BE MINIMUM 72" OVERALL LENGTH AND BETWEEN 30" AND 42" WIDE (LENGTH MEASURED FROM HANDLE END TO NOSE END OF CAR, WIDTH MEASURED FROM WHEEL CENTER TO WHEEL CENTER).

MINIMUM RAOD CLEARANCE OF 3".

THIS WILL REQUIRE 2 SCOUTS -- 1 TO DRIVE, AND 1 TO PUSH, 150' LONG TRACK.

ANY SUGGESTIONS? ANY HELD ANYONE CAN OFFER WOULD BE GREATLY APPRECIATED! THANKS.

Pat, Cubmaster
Pack 434

Your post would be easier to read if it was in sentence case, not in all caps.

You may do some searches outside of this site for cubmobiles, and also Soapbox derby cars since your plans call for enclosed cars and possible cable steering. Is there any rule on the wheels/tires other than 4? Keep tread width narrow, and no grease in the bearings. I have a set of our packs rules, but they are different than yours. Use you imagination, be creative, keep the center of gravity low. Safety first for everything. If I can help more, let me know.

That sounds like very complex rules for a Cubmobile.
However, one hint I do have for you -- lauan doorskins.
They're essentially a 3-ply 1/8 inch plywood. Lowe's and Home Depot sell them for six or seven dollars for a 36 inch x 80 inch sheet.
One side is very nice, the other side may have some cosmetic flaws.
If you use a stressed skin type of construction, it can be very stiff and light.
Urethane glue ("Gorilla Glue" is one brand name) is a pretty forgiving way to fasten it together.
Also, see the Wheels thread for a discussion on wheels
http://www.comtech2000.com/index.htm will get you to a wheels website.
If you drop Richard Lemmon an email with "Cubmobile" in the subject, you can work with him to order small quantities of wheels at essentially his cost.
However, his spam filter ignores email without the "Cubmobile" subject line.

I don't have plans for you -- I tend to "just start building", and in any case, our rules are not as complex.

Check out the vids here... the yellow car and the orange car both are our "creative steering" designs.


The hand steered car is too hard to steer (wood and bolts don't work like metal and bushings/bearings... they bind due to side load from wood compression distortion of the basic geometry in the linkage).

http://derbytalk.com/viewtopic.php?t=1893


Our goals this year: Take the orange car (or unpainted in some of the videos) and simply revert back to foot steer.

These cars offer way more control (desensitized steering) and "pinewood speed secrets" in their design.
Raised right front wheel (also means no steering scrub)... heavy rearward CG... offset seating to keep the raised wheel raised... these are flexible compared to a Pinewood car.

Our only real "speed" improvement this year will be to spend the CMB budget on 4 new wheels... plan is to use them for summer time fun (no lube necessary)...

the current wheels will have the grease seals removed and be cleaned out, then re-lubed with WD-40 (fresh application per run at the race).


-Terry

Hi Pat, how did it go?

Sent 2-3 e-mails and no replies...


Hope he didn't give up and walk...


he missed a lot of fun if that happened.


-T