Power and couple with several motors

[h-g-t]

I don't think building a dragster which will wheelie is impossible - http://www.youtube.com/watch?v=cMz2sZLy81s - but using a sensor to keep it at a constant angle might be.

An alternative might be have a touch switch connected to the 'tail' which stops it flipping over backwards.

The power could be cut when the switch is activated by hitting the ground then re-applied when the switch is off again, but I suspect that it would 'kangaroo', like a learner driving a car for the first time! Especially on rough surfaces where the bumps, rather than the angle, could trigger the switch.

Why not just apply plenty of power to keep the nose up, possibly by gearing up instead of down?

Using 'power function' motors would give more power, but that would mean another battery box (more weight) unless you drive them from the NXT using convertor cables. Mindsensors are bringing out a device which will allow a NXT to control these motors as if they were NXT units (one per motor).

If you want even more power, one of these will run a single motor at up to 18V - http://www.mindsensors.com/index.php?mo ... AGE_id=140 and gives proportional speed control. You would need one for each motor.

I think that the angle will be self-correcting once the 'tail' hits the ground because any increase in angle will start to lift the wheels off the ground, so power will be lost and the angle reduced automatically.

The biggest problem would probably be keeping it straight since the front wheels will be off the ground and any imbalance in weight will mean that one wheel is likely to lift before the other, sending it off course. As are any differences in wheel diameter, grip, axle friction, etc.

You could try making the 'tail' steerable and put a small wheel on it but then you have the problem of monitoring and changing it fast enough, just as for the angle.

You could try separate motors for each wheel to give some steering that way but how do you measure what corrections are needed (and apply them) quickly enough? And no two motors give exactly the same power at the same setting, just to make things worse.

If you have fast reactions you might be able to leave the NXT off and direct it using a proportional radio control set to vary the wheel powers (or a small rudder at the very front?).

Dexter ( http://www.dexterindustries.com/ ) have some very sophisticated sensors but I don't know if even they can operate fast enough to keep the dragster running straight. They are fast enough to run a Segway so it might be possible.

You have picked a very demanding type of model and I will be following your progress with interest.

[floppi]

My idea is just to use a basic NXT 2.0 Kit, I do not want to buy other stuff.


And about the dragster, the idea was to build a dragster, when it runs the nose is on the air ! Not a balancing nose who stay in the stair when the car is forwarding/reversing !