kistinie
04-03-2009, 04:59 AM
Electric propulsion and regeneration for under 10/12 Knts sailing boat is a rather simple thing as the close to square effect of speed for torque applied on the propeller remains acceptable.
But in the case of a well designed cat, tri or prao reaching 15 to 20 Knts the drag effect and vibrations will become a real problem. I do not speak of racer reaching 30 Knts, even 45 in case of Orange or IDEC where effect is dramatic !
Obvious solution would be a Variable Pitch propeller (we say in french), CPP in English (thanks m-saha for recall to order !), but this solution is expensive and it seems industrial products are missing for power range around 10Kw
Autoprop is a part of solution but above 12 Knts, i doubt it works
Other solution would be to have two distinct device
one big pitch to motor and regenerate low speed, then fold
second small pitch producing energy for high speeds
Of course in both cases the motor controller, playing on regenerating curent can also control the torque applied on propeller, but is this enough for very high speeds ?
Is there a distinction to be made between shaft drive and pods ?
Last thing to think about is that in case of surface propeller experience shows that you collect plastic bags, sea weeds and other net, that block the regeneration...
What inspire you these two solutions ?
Do you have others ideas ?
A gearbox ?
A reduced propeller diameter and increase Rpm to the cost of a reduced efficiency doesn't please me very much, but may be is this just a bad preconceived idea ?
But in the case of a well designed cat, tri or prao reaching 15 to 20 Knts the drag effect and vibrations will become a real problem. I do not speak of racer reaching 30 Knts, even 45 in case of Orange or IDEC where effect is dramatic !
Obvious solution would be a Variable Pitch propeller (we say in french), CPP in English (thanks m-saha for recall to order !), but this solution is expensive and it seems industrial products are missing for power range around 10Kw
Autoprop is a part of solution but above 12 Knts, i doubt it works
Other solution would be to have two distinct device
one big pitch to motor and regenerate low speed, then fold
second small pitch producing energy for high speeds
Of course in both cases the motor controller, playing on regenerating curent can also control the torque applied on propeller, but is this enough for very high speeds ?
Is there a distinction to be made between shaft drive and pods ?
Last thing to think about is that in case of surface propeller experience shows that you collect plastic bags, sea weeds and other net, that block the regeneration...
What inspire you these two solutions ?
Do you have others ideas ?
A gearbox ?
A reduced propeller diameter and increase Rpm to the cost of a reduced efficiency doesn't please me very much, but may be is this just a bad preconceived idea ?