1/8 scale cracker box cornering problems ?

[riggerman]

Hi all some years ago i built the Jerry Dunlap 1/8 scale cracker box from the plans in the Jan 1996 RCBM magazine .I set the hull up for brushless power with a Leopard 3650 3900 KV on 2s swinging a x432 prop . When i built the hull i made sure i had razor sharp edges between the transom and hull bottom and razor sharp edges between the chines and hull bottom . The boat chine walks and bounces down the straight aways at 35 mph just as a cracker box should the problem is the turns i slow down to less than 1/2 speed and set up to turn many times the hull just seems to grab and flip on its deck i have also tried turning down the steering rate.The only thing i deviated from the plans is my Dorsel fin is 1 1/2 inches deep instead of the 3/4 inch deep as shown on the drawing. Could this be the problem ? What else could i do to fix this issue ? Regards Andris Golts.

 

[rhomodel]

Chinewalk is inherent to any flat bottom V-hull. Because the underside is flat it will trap a lot of air and the boat becomes unstable, very susceptible to any disturbance.
What come to mind did you check the correct CG? Experiment: may be moving the battery pack around, of just add weigh to the front. Also left-right balance (starboard -portside).. Is your steering absolute wiggle free?

 

[Grimracer]

Rigger man.. do you have the prop out the transom? If so consider putting it under the boat.. Leading edge of the prop 15% from the transom..

 

[Rudy Formanek]

Pics of the bottom and pics of the strut setup would be very helpful.

 

[Mike Hughes]

Sounds about right on all the crackerboxes I have seen. Like stated before, they dont turn so well.
Mike

 

[riggerman]

Thanks to all for replying to my post . Regards Andris Golts.

 

[Grimracer]

They can be quite amazing IF.. you get the prop in the correct spot under the boat..

Grim

 

[RobertDoak]

I spoke to Mr.JD. about this boat in the past...I had a buddy give me the same boat all cut out just needed assembly...I talked to Jerry about the boat and he made sure I understood what this boat is...a fun crackerbox for a weedeater motor....so I wrapped up the boat and gave it back to the guy who gave it to me....then ordered a Zippkits Crackerbox...but back to your boat..you may not have enough physical weight in the boat....only a 2 cell battery and motor....try some dead weight just for ballast and a 3cell battery

 

[Wasted wages]

I have a glass crackerbox I bought off someone here on IW years ago. I don't know who built it,
I bought it without the motor, and bought a CC promod motor to put in it..

The thing is a blast to drive!! I have more fun with this boat than anything else I own.
With the fuel bag I have in it, I have gone out and made over 100 laps before bringing it in..

Whoever set it up did a great job as it corners perfectly and only gets flighty if I run it hard into the wind.. I'll try to post up a picture of it and maybe someone will recognize it or know who the previous owner was .

 

[Jerry Dunlap]

You might want to try a transom turn fin mounted to the right side of the transom.
JD

 

[LohringMiller]

The gas crackerboxes run a center fin, a transom fin and often a skeg. See below.

Lohring Miller

 

[riggerman]

Thanks again guys for your input . Jerry i do have a turn fin on the starboard side trim tab that is 5/8 of an inch deep and 7/8 of an inch wide. Regards Andris Golts.