Discussion Crackerbox Racing Class Boats 1/10 Scale

[Hoghappy]

I did a search and read every letter typed here on this subject and think we a need a thread dedicated to this boat....so....

I think this is my first thread in this forum...I usually hang in sailboat and docktalk ....and my fast electric knowledge is very limited but here goes!

I started a boat club last fall and although it's mainly a sailboat club right now, some of us have a need for speed. My Batfisherman (see pics) has attracted interest and now I want to expand to an inexpensive, easy to build and fun, fun, fun boat to get a new FE Class going.

I'm looking at the vac-u-cracker http://www.vac-u-boat.com/Vac-U-Cracker.htm very hard. Anyone have this and is it a good choice? What are the in/outs? What rules would you have to keep things cheap and fun?

Capt. Crash

[n.h.schmidt]

Hi Capt Crash
The Cracker Box is indeed a fun class to race.Very competive too. It is a racing class with namba.They are jumpy little boats and usually run at about 20mph. They should stay submerged drive to keep them about the same. All should run with 27turn Roar Stock motors and six cells. As they are easy to flip ,a recovery means is a must. Others may suggest stronger motors but really the boat can't handle any more speed .
The Vac u boat looks to be a very good deal for this boat. n.h.schmidt

[gpzy]

There is a Yahoo group for the crackerbox. http://groups.yahoo.com/group/CrackerboxRC/
I believe Microglass makes a crackerbox.

[ROADTOAD]

by all means take a look at our yahoo Cracker group, we now have 24 members with plans on the site. Link in above post.

Also I have a bunch of Cracker links on it also.

[Hoghappy]

I think I have at least myself and 2 others, maybe 3, ready to go for the vac-u-cracker. I don't intend to join the National Organization, just start a local fun to run group within our club. Now that the Nirvana race yacht class is going good with our 12th boat joining today, I'm ready to expand the club to something more adrenalin producing. I think to get it up and going I will stick with my proven formula of fun, easy to buy/build, inexpensive and competitive without a lot of options or in other words “one design”.

I’m undecided about the motor/battery choice. The good R.O.A.R. legal motors are not cheap. The motor I use in my boats is the stock Bristol Bay motor by Hobbico used in a lot of Aquacraft boats. It runs pretty good on 7 cells but I don’t know if it will be up to the task on a 6 pack and how the boat will handle the extra weight of another cell…or if the motor will do ok in the heat dept. without air or water cooling. The one on my “Batfisherman” is running very cool on 7 cells after 15 minutes of run time, but it has both water jacketed cooling and air moving through the cover. I may just try the cheap $12.99 Bristol motor with both 6 and 7 cells and torture test the crackerbox to see if it is a viable option.

Here are some pics of the new paint scheme tested this weekend on the Batfisherman. The kids love it and want to touch it when it’s out of the water. I think I will be able to attract more people to the club with this class of boat (crackerbox) than another sailboat. The brushless boats like BJ -26 and SV-27 are too expensive and fast for the ponds we use to race in anyway.

Here is our Club website:http://www.orgsites.com/al/montgomer...lub/index.html

Capt. Crash

[Rex R]

iirc a 'stock'(27t 05 motor) motor ran me $40, the 19t motor was $5 cheaper(I wouldn't go with anything lower than a 19t in a c-box)

[Hoghappy]

I think I want to go ahead with the following for my first crackerbox:

Vac-u-cracker with stock hardware setup and 6 pack
Trinity Monster Horsepower Stock Pro Motor
Associated A.I. Quantum Runner Reverse (super light weight and waterproof)
DX6 receiver

The above should give me a very light boat.

1. If this sounds like a good combo...will I need water cooling? I noticed a lot of the boats on the websites have the cooling in their crackerboxes. That 540 can does not look like it will allow traditional wrap around cooling because of the air holes. Does it even require water cooling in this enclosed boat?

2. I have some 3000 and above NiMH 6 packs and wonder if these will overwork the setup.

3. How long can this boat run at full speed with this setup before it needs to be shutdown? 5 minutes? 10?

4. You guys fusing the boats? I like to use the inline flat 30 amp automotive ones in my other boats.

Ok…as soon as know what will work I can get my order in.

Thanks

Capt. Crash

[Rex R]

usual race length is 1/2 mile(1.5-2minutes), you might not need to add water cooling for a 2 min run. however the standard coil will work(tho you might consider spacing the turns out a bit).
fusing. er not that I've heard.
runtime; only one sure fire method is to run for a bit check temps(allow to cool) run a bit longer etc.( tedious yes but, hey its research ), I suspect that 5 minutes might be pushing it. remember to; use a min of 14ga wire soldered to the motor(not push on connectors...they 'burn', btdt), don't use tamiya connectors. hth
rex

[Hoghappy]

I converted to "Deans" connectors in about everything I float and a fuse is my friend when wrapping the stuff around the prop.

A couple minutes run time is not good!

Capt. Crash

Edited to ask...does anyone have pics of how cooling is being added to the vac.u.cracker...especially the pickup tube?

Does this slow the boat with the extra drag and weight?

[ROADTOAD]

If your looking for a fast build Crackerbox, get the Vac-u Cracker. The guys here run them as listed on Vac-U-Boats website. The price is right. I live about a hour and 15 minutes away from Vac-U-Boat.

You can pick up the Trinity Monster off ebay cheap in new condition.

Any esc rated 30 amps or more is fine, most guys don't watercool but, we did years ago, it was easy enough to do.

As for juice, a 6 cell 3800 NiMH battery will do the trick.

The class was ment to be a "fun class" where you don't have to spend big bucks to be competitive. Driver skill and a boat that keeps running upright will win.

If you want to see the real Crackers run check out these videos:

cracker box racing (0 min 58 sec)

[ROADTOAD]

Here's some more:
http://www.youtube.com/watch?v=b-2Cn...eature=related

[Rex R]

the factor that limits run time most is how hot the motor & esc(not to mention batteries) get, 150F should be considered the upper limit on all of them. I haven't had any experience running either a c-box or a 'stock' motor. so I'm just guessing about run times. my 19t boat has enough mah to run for more than 4 min...but the esc will thermal after about 3. the vac-u-cracker has a larger internal volume of air availible to help cool things than my boat. so they should be able to run longer before getting close to meltdown(if they get that hot) hence the reason for tracking temps for the 1st few runs. once you know the run charateristics, you can adjust the race lengths so that you won't destroy your electronics. two minutes of trying to avoid hitting course markers and other boats is a long time

[ROADTOAD]

If I recall correctly, back in 1997-98 I raced the Cracker up in Canada it was 10 laps and the races lasted about 5 minutes. And that's before they had nimh 3800mah batteries.

[pompebled]

Originally Posted by Hoghappy

A couple minutes run time is not good!

I agree, the runtime in our Mono-1 class is 8 minutes, racing around a triangular course (30 x 30 x 30m), great fun!

We use 600 closed can motors, 7 cells and a 36 or 37,5 prop in surface piering drive.
A cracker with a 19T car motor on 6 cells should be able to run at least that long on a modern racing pack (3000-4200mAh).

As mentioned above, the long runtime causes a formidable heat build up in the motor, resulting in jammed brushed and melted endbells...
Watercooling is mandatory if you want to run that long; a coil around the can helps, but adding brushcooling does the trick, transferring the heat from where it's generated, at the commutor.
Also a motormount that doesn't obstruct the cooling slots in the motor, ensuring airflow through the armature, is vital.

In our monohulls we have the intake directly next to the motor, a brass/alu tube glued in the hull, facing forward and sanded flush with the hull for minimal drag.
The outlet is also in the bottom, but facing towards the transom, sanded flush like the intake.
This creates sucktion and assures the flow in the system.

Don't worry about not being able to see a 'fountain' at the outlet, this cooling system allways works flawlessly.

The added drag is minimal, my son was European champion with his boat with this cooling system, beating other 'speeding fountains'....

If you need some pics, let me know, I can add them later today (I'm currently at 'work').

Regards, Jan.

[Hoghappy]

Originally Posted by pompebled

If you need some pics, let me know, I can add them later today (I'm currently at 'work').

Regards, Jan.

Thanks Jan...I would like some pics if it isn't too much trouble. I think this would be a good alternative to the transom or rudder mounted pick up tube. I would still like to see some pics of those setups too. What about ESC cooling?

Capt. Crash