Blast Car Ideas

Anything related to CO2 powered racing, such as Blastcar, and event coordination.
Post Reply
quadad
Master Pine Head
Master Pine Head
Posts: 494
Joined: Wed Jan 23, 2008 12:51 pm
Location: SE, WI

Blast Car Ideas

Post by quadad » Tue May 06, 2014 8:14 am

I decided to take the plunge and build one of these for an upcoming Scouting event. I haven't learned much about what people are doing to make these fast yet though. So far I am planning on the following:
- 4 wheels all touching
- Canted rear axles
- Pointed nose
- Wide Profile
- Rear wing above the block
- Distributed weight front/back, just a hair over 5 oz total wt
- CO2 cartridge hole low to the ground
- PWD style axle and wheel bore prep
- Polish the eyelets
- Just over a 7 1/2" wheelbase

Comments ?? What am I missing ???

Not sure how you polish these axles. Might have to screw them into something that can go into my drill press. I see grooved axles for sale, which might be best for oil.

I am not looking to make this a whittling project. Will probably mostly use a table saw and band saw to cut on the block. I am thinking I can drill the starter (3/32") axle holes with my PWD setup.

I saw in the kit instructions that they would allowing relubing between heats. Is this typical ?? I was leaning toward oil rather than graphite. Once you do oil, you really don't ever want to see graphite again.

Thanks !!



quadad
Master Pine Head
Master Pine Head
Posts: 494
Joined: Wed Jan 23, 2008 12:51 pm
Location: SE, WI

Re: Blast Car Ideas

Post by quadad » Wed May 07, 2014 6:58 am

I had another thought on the wheels/cant.

Since there are no restrictions on what you can do to the wheels, I am wondering if using an old fashioned "H" pattern cut into the tread wouldn't be the sweet way to go along with flat "axles" (screws). This is almost always outlawed with PWD races, but I see no restrictions on wheel treatment in the BlastCar rules that come with the kit. The only thing holding one back, I would imagine, from narrowing the front wheels is that the bore is of limited length and the wheel is pretty hollow with BSA writing on the outside (which I am pretty sure inspectors would want to see).

As it is, my drilling block won't hold the BlastCar 2.25" wide body, making drilling a little more problematic. Flat axles holes will probably be easier to accomplish with my well-aligned drill press table, though I have another ace up my sleeve (using an old tool discussed elsewhere here) should I want to cant.



TXDerbyDad
Master Pine Head
Master Pine Head
Posts: 185
Joined: Wed Dec 12, 2012 4:04 pm
Location: Dallas, TX

Re: Blast Car Ideas

Post by TXDerbyDad » Thu May 08, 2014 3:04 pm

The Blast Car program was ended by BSA at the end of 2013. :shake:



quadad
Master Pine Head
Master Pine Head
Posts: 494
Joined: Wed Jan 23, 2008 12:51 pm
Location: SE, WI

Re: Blast Car Ideas

Post by quadad » Fri May 09, 2014 6:15 am

TXDerbyDad wrote:The Blast Car program was ended by BSA at the end of 2013. :shake:
I had heard something about that. It's a good reason to not 'invest' in stuff for continued racing, but it has absolutely no bearing on my plans or the upcoming race. We're still building and racing. There is a good chance that we will have two cars also ! It's cheap entertainment. :dance:

Any comments on my plans ????



User avatar
whodathunkit
Pine Head Legend
Pine Head Legend
Posts: 1921
Joined: Sat Apr 25, 2009 5:56 pm
Location: Forgan, OK

Re: Blast Car Ideas

Post by whodathunkit » Fri May 09, 2014 5:15 pm

What type of surface will the blast cars be racing on ?
would be first thing to look at for designing the car.

Dragster, rail car . Shell, platform or pod. Hybrid or novelty.

Sounds like your on the right track for the wheel prep.. the oils will work well!
(if not racing out side on pavement or on a dirt surface.)

For preping the axles you can try this tip:
try drilling a hole in a dowel rod and threading the axle into it
then chuck the dowel rod end in a drill press.

Eyelet placement on the car also has alot to do with how well the car will track down the string.

Make the car body and wheels as light as you can..
for getting the top speeds on a smooth surface.
And that it also tracks in a true line.. no drifting down the string.

And just because the Blast car program may have ended in 2013..
there are still kits to be had and to build the cars with.


What type of automobile can be spelled the same forwards & backwards?

User avatar
whodathunkit
Pine Head Legend
Pine Head Legend
Posts: 1921
Joined: Sat Apr 25, 2009 5:56 pm
Location: Forgan, OK

Re: Blast Car Ideas

Post by whodathunkit » Sat May 10, 2014 9:36 am

One I'v been working on.
Image

Have fun!
Whoda.


What type of automobile can be spelled the same forwards & backwards?

quadad
Master Pine Head
Master Pine Head
Posts: 494
Joined: Wed Jan 23, 2008 12:51 pm
Location: SE, WI

Re: Blast Car Ideas

Post by quadad » Sun May 11, 2014 11:31 am

Very cool ! :bigups: Thanks Whoda !

That's not a world from what I am thinking (and has given me a thought or two).

Where are your eyelets at and how far off the ground do you have the holes ?



User avatar
whodathunkit
Pine Head Legend
Pine Head Legend
Posts: 1921
Joined: Sat Apr 25, 2009 5:56 pm
Location: Forgan, OK

Re: Blast Car Ideas

Post by whodathunkit » Sun May 11, 2014 7:18 pm

quadad wrote: Where are your eyelets at and how far off the ground do you have the holes ?
quadad,
For the blast cars.
The axle hole locations should be between 1/8'' and 3/8" above the bottom of the car
if you will be racing the cars with the race line.

Any higher up then 3/8" on the axle hole locations on the car it will be to low
to fit on the race line with the eyelets.

With the 1/8" axle hole locations the eyelet hooks should be at 3/8" off the race surface.
And with the 3/8'' axle hole locations the eyelet hooks should be at 1/8" off the race surface.

The blast car seen in the photo above:
Is running with the 3/8'' axle hole locations and will be running on a smooth tile floor surface.
The eyelet spaceing on the car are at 1" off of each end.. with 8" in between the eyelets.

A good tip for playing around with the eyelet / guide spaceing on the car.
Is to drill several small holes down the center line of the car bottom at 1/2'' or 1" spaceings...
so the eyelet / guides can be changed up if needed.

Heres a photo:
Of 1947 Monogram Models CO2 car instruction sheet showing eyelet / guide spaceing.
Look for the eyelet / guides on the two photos seen on very bottom of the sheet.
Image

Hope this helps!
whoda.


What type of automobile can be spelled the same forwards & backwards?

quadad
Master Pine Head
Master Pine Head
Posts: 494
Joined: Wed Jan 23, 2008 12:51 pm
Location: SE, WI

Re: Blast Car Ideas

Post by quadad » Mon May 19, 2014 1:08 pm

Well it was a one-day (hour or two) build and I guess it was worth it since it was fun seeing it run and I had some success.

I had to keep it simple with the time crunch, but here are some design/build aspects (not sure any is the best advice, just documenting what I did):
- Wheelbase was 7 5/8" with the rear eyelet in front of the rear wheel (clearing the CO2 hole) and the front eyelet between the front axle and the back of the front wheel.
- I first drilled axle holes 9/16" off the bottom of the plank. After checking how square the block was and determining the best side for drilling, I laid the bare block on my shimmed plumb drill press table and drilled straight through the from one side to the next). and then cut 5/16" off of the top and the bottom. Yes - this axle height and the CO2 cartridge wall thickness is against the prescribed "rules/instruction" but it worked with their BSA launcher and got my car closer to the ground (thanks for the tip Sporty !).
- I drilled the holes with a #43 solid carbide bit (standard issue for adult PWD), but later opened the holes up further with a hand tool and larger bit.
- I then did normal weight hole work and car shaping. I went with a pointed front and pretty much straight slope down from the CO2 cartridge forward.
- My finished block was a little over 2 oz. yet, so I added a little more than 1 oz in the nose of the car. I would have liked less weight yet in the back, but the front did not raise during launch (best I could tell, it was Sooooo fast).
- My axles were polished and I prepped the wheels with modern day best practices (almost) as far as PWD wheel bore prep goes. I didn't have time to true the wheel tread or try to lighten the wheels.
- I used PWD car oil (krytox plus) as lubricant. Thought it would be at least as fast and quicker for me to do. I put more drops on than I would on a PWD car wheel because I was worried about the speed of rotation, length and number of heats being a lot more than for PWD.
- Because of my rush job build, I had to attach the axles/wheels to the car at the event. I had misplaced the included odd-ball allen wrench and couldn't get one there so I tried everything in our Troop tool box, including a set of English and Metric allen wrench's, driver bits, Torx, etc., and NOTHING fit. I think I learned later it's 2.7mm or something like that so I had to insert all axles, and severl for the first time, by using a pliers on the outside of the head !! :angry:
- The race was run on a not-so-clean concrete floor in essentially a large barn.
- I took first in the Open class over not too many other racers in that class (5-6 ?), though I think there was a faster Scout car there. To make it more exciting, I just barely lost (I think) the last heat and my car wrecked on the stop section with both front struts/wheels breaking off. :sweating: It really didn't matter as I am not likely to run it again.

It was fun ! Thanks to all for their help ! :dance:



Post Reply