Hub Bars and Starter Motors

[asra]

I have no idea about torque and so on but when starting my rotors I always start by hand up to about 20 to 30 rpm leap into my seat and then engage the pre rotator starter motor, surely this should dramacticaly reduce the forces on the hub barDavid Skett

[asra]

I tend to agree that a hot resister could be dangerous, and it certainly is wasted electricity/energy.Aussie Paul. []www.firebirdgyros.com

[NiqueNaque]

Here's a way to think of it....Torque is like a see saw or beam scales. The bolts have to oppose the torque, so they are the balancing side of the see saw to what the starter motor puts in as a pre rotator.In this instance the starter motor input is 260 ft lbs at a 10:1 ratio, so on the fly wheel rim it multiplies the torque to 2600 ft lbs on the rotor, from 260 x 10 = 2600.The bolts have to resist this, however, they are 1/10 of the distance in, so they suffer 10 times more force, see the image below:Image Insert: 9.44

[NiqueNaque]

Paul,Is it any differnt to a hot exhaust?The energy losses through heat will only occur on soft start being activated, but the savings in lives and damage to rotors would be well worth the minor cost of a couple of watts of energy.Cheers,Nick.

[Greg Mitchell]

Took the words right out of my mouth. I think I'm takin a big RISK agreeing with you Nick.Mitch.www.thebutterfly.info

[Greg Mitchell]

We should have the complete wiring diagram for Monarch Soft Start soon, along with a detailed description of Function/Operation. I'll post relevant info as it comes to hand.Regards,Mitch.www.thebutterfly.info

[NiqueNaque]

John.To your knowledge has anyone tried an a/c motor with a variable speed controller on it?Greg,Thank you. Hope you are enjoying your balancing act.Cheers.Nick.

[asra]

[asra]

What about trying the motor out of one of those granny-scooters. Surely the donk in those things must have some torque, and the speed control bit is already built for you.L.Magner

[asra]

John,Have you measured the amps drawn by your motor bike starter under load and with no load? Dick Smith sells kits for speed controllers that will handle 20 amps. I once tried winding up a set of blades with a cordless drill. I had a ring gear and pinion with 13 -1 reduction, the drill had 1100rpm no-load speed which turned the head to 75 rpm. With the blades on, and feeding the power gradually via the trigger, the max speed obtained was 45rpm due to the battery contacts overheating. In a cordless drill the motor goes like hell and the gearing does the rest. As a consequence, the wireing is light and the current to be controlled is less than slower, more powerful motors.One way you may be able to control your starter speed is by cutting into one of the field coil leads and inserting a variable resistance.This will change the magnetic field which alters the speed.What is the final drive ratio of your chain and sproket reduction to the head?With a controlled wind up, you can keep the pre-rotator on the whole time you are taxiing, until the blades exceed the the motor and disengage the pinion.Rats.

[Greg Mitchell]

John,I'm sure Nick and I can find common ground on many issues, we seemed to be over the worst of it But HOLDING HANDS!.......Went to Launie today located a solenoid same dimensions as Larrys, only thing is instead of one lug connector (apart from the two on side which coil attaches to), there are two mounted on top in a V shape. How would this affect the wiring process, given you helped Allan with his.It's an ST80 Solenoid cost $63. Generic Brand has slightly longer casing and is 841157 cost $40.24The soft start is engaged at the same time as the main starter solenoid and robs it of power allowing for a slow initial wind up. It is engaged for approx 4 seconds. The starters Larry sent he says are rated at 1.4 hp and should give 140-150 rrpm.I sourced some starters today range from 1.4 to 1.7 kw prices ranging from $156 -$320 all these starters fit our pre-rotator plates perfectly. Can anyone help with comparisons for me and give me an idea as to rrpms expected from these kw ranges? Appreciated.Mitch.www.thebutterfly.info

[asra]

[Brian]

I'm not a technical person but I reckon because there are a lot of gyro's out there that have a fair few hours up with electrical starter motors as pre rotators and havent caused any problems, I just think that there's no where the force on bolts that you guys reckon. Now, this might be because most of us give the rotors a big shove to start them, and when the starter motor is engaged, a lot of the "kick" is disappated. If there was as much force as its been said, then surely the aluminium rivets on the flywheel would surely let go first!While you are doing these tests John, it might be a good time to test batteries as well.I only used to get about a year out of a battery before changing to a sealed battery.

[asra]

You can't do much about a hot exhaust. I would just like to be able to do it without heat and loss of power!!!!!!I wonder how Jeff Hunt from the US does his commercial "soft start" electronicaly? I know John Potter uses it on the 30'Raf blades on the Twinstar.The non geared starters can apparently be modified inside as in an earlier post.One way you may be able to control your starter speed is by cutting into one of the field coil leads and inserting a variable resistance.This will change the magnetic field which alters the speed.Aussie Paul. []www.firebirdgyros.com

[asra]