Pre-rotator Challenge!

[KenSandyEggo]

I copied this over from one of the other threads as it seems more apropos here.


Hey, Mike B., what is the deal on your dad's prerotator? Will it work with Soobs and what are the numbers you guys see? It seems like the topic is not well discussed (all prerotators). It would be nice to get consistent runs close to 200 rpm. The guy that whacked his 2 sets of blades and let me try his Sportcopters can get up there in his RAF. I looked at his setup and it is absolutely no different than mine. I tried his for a few flights and some prerotations and there was no problem with getting them near 200 at just above idle without the aid of any wind. He said his secret was lubing the shaft with refrigeration oil. I tried it and it helps for awhile, but he hadn't re-lubed his in about a year and he was still showing those numbers. I don't get it. Mine starts slipping near 1400 rpm and I'm usually around 100 to 125 on the rotor tach and he's getting 190 or so.

It is way overdue for some ingenious person to come up with a prerotator system that will consistently achieve 200 rpm without burning up the battery or carrying an extra 100 pounds along; that is economical, reliable and consistent. It seems to me to be an area where we're really lagging. We're sporting all that horsepower on a lot of the machines and it shouldn't be that difficult to harness some for decent rotation speeds. We need some clever engineer type to make the breakthrough. Sales would probably be phenominal, even considering our relatively small numbers.

I was really impressed when John Potter took me for a ride in an Air & Space and spun those blades up. I believe they get up to around 450 for the jump take-off. Of course the blades are flattened to help out, but if some 2-time blade-whacker can get those 190 numbers on his RAF without really knowing why, someone should be able to push us over the hump. Couldn't someone slightly miniaturize a version of the A & S system for us poorer slobs?

I thought that if we could replace or modify the clutch face with some direct connection there that could be engaged and disengaged, we'd get those numbers easily. How about using the same clutch assembly and then when the blades get over 100 rpm, engage some sort of spring-loaded pin(s) device that would pass through both plates/faces of the clutch, engaging them solidly. Upon reaching 200 or whatever, the clutch-faces and pins could be easily dis-engaged. It wouldn't have to be pins passing through, just something that would grip the 2 metal clutch faces and prevent them from slipping and/or disengaging.

O.K. If no one wants to do it, I will get some design engineers to perfect something and you guys are going to pay me up the wazoo for one. If you don't want that, get cracking on figuring something out.

[TomCarlisle]

I have no problem getting 260 rrpm with the Dominator hydrolic pre-rotator. I can apply full power at that point and get airborn in a VERY short distance. Engine rpm is in the 3500-4000 range and the brakes just do hold. Wheels are starting to slip. If I could hold the 360 pound Dominator in one place, I feel I could easily get 300 rrpm. Torque is just too much to leave the pre-rotator engaged while rolling.

[TomCarlisle]

PS. I forgot to post that Ernie Boyette has fitted his pre-rotator to a sub4, so it should be easy to adapt to RAF or AAI.

[MikeBoyette]

Tom,
Thanks again for dinner Sir. I really enjoyed hangin out with you at BD's.
Hey Ken see my post in your threads other location.

[Dean_Dolph]

Hey, Ken, you can run but you can't hide so if you move your message then I move my reply!

Ken, there are two pre-rotator setups that I would want to try if building a new machine. The first (because I understand how it works!) is the setup that Richard Oxnam (better know as Mary Jane's husband!) has on his machine. It supposedly gets consistently more than 200 rpm. In fact, as I recall, there was a report on Norm's conference that he was able to get 300! If my memory is fuzzy wrong then in the famous words of K.J., 'never mind'.

If I'm correct, Dave DeWinter used this same setup and refined it but I don't recall if he ever reported what rpm he was able to get. The setup uses the typical rubber friction wheel that rotates against a drive plate. But in this case the drive plate is mounted on the front of the engine instead of the typical drive arrangement that you have. It uses a square tube sliding joint shaft with the requisite u-joints (as I recall, I can't find the pictures at the moment) to connect with the Bendix. Dave, jump in here and clarify.

The setup that really intrigues me is the one that Dick DeGraw had on his dominator hybrid at Bensen Days '03. As it has been described to me, it uses a cone clutch. It should be capable of cranking up the rpm with little or no slippage if mated someway to the output arrangement like Dave has. It would probably require a right angle drive of some sort. Presently Dick has it direct driving a hydraulic pump. No belts, no rubber wheel and no slippage!

Here is a link that shows an animated cone clutch for those that need a visual (I do!) explanation. http://discover.edventures.com/functions/termlib.php?action=&termid=415&alpha=c&searchString=

If someone could talk Dick into designing and developing a unit that incorporated the cone clutch and right angle drive into one unit then I believe we would be in for a quantum leap in pre-rotation. Also, the rubber wheel, the flex shaft, belts and the hydraulic pumps would be eliminated.

Dick doesn't toot his own horn and for some reason no one reports on all the little ingenious things he develops. A person will miss a lot of them unless you look very closely at his machines and even then it is likely they will get overlooked unless you get in a discussion with Dick and they get mentioned in passing. It is obvious that he creates these devices to satisfy his personal needs and apparently gets satisfaction from doing so without the accolades. The accolades naturally follow and can't be avoided when the Sychrocopter, the award winning jump take off machine and Carol's De Bird among other stuff, are displayed. It is not fair that one guy has all this talent!
__________________

[Mike Hook]

Just a thought on a drive for a prerotor, at the mines we used a drive called a CST ( constant drive transmission). It had a input shaft and a output shaft and also a brake shaft. The brake shaft had a brake rotor on it with a rotor brake. When power was applied to the input shaft there was rotation out the brake shaft and none out the output shaft. As the brake was applied the output shaft started rotation till the point that the brake rotor locked up then it was a direct drive unit. This unit is also used in pulling tractors so instead of braking one side of the tractor to make it steer right or left you just left off the cst brake on the side to want to slow. This makes no lose of power as on a conventional brake as you know a steering brake on a tractor.
Any way if you build a small CST unit you would be able to lock your drive up and hold the power on to the prerotor without slippage. The gear box on one could be quite small. Just something to think about as a different means of drive output .


Mike Hook

[Mike Hook]

Correction:
I had called the CST unit a constant drive transmission it is a constant speed transmission. We rand200 hp dual drive motors on 48" wide 2 mile long convair belts load with coal and mud so they are tough. Just think of them as a car rear end and the brake rotor goes on one side of the axle and the output on the other. The more I think of it this just may work well.You could use a hydralic caliper off a motor cycle and rotor too. light and efficient. The biggest problem to a CST is constant trys to restarting due to heat on the rotor brake.This sould not be a problem with the prerotor because your not restarting over and over.

Mike

Mike

[Mike Hook]

More thoughts,

If you used a CST you would not need a right angle drive you already have one and it could stay on all the time. When you wind up your rotor and start takeoff, just let off the cst brake and the drive will no longer out-put power the brake rotor will just spin.

Damn this may work yet,,, let see what is the patent office number????


Mike Hook

[Mike Hook]

On a roll here now should be working here in office.

The CST drive could be mounted on the front of the engine and use a toothed belt to drive it, better power transmission. Now all you have to do is run a shaft up to a bendix drive on the rotor head. I am sure this will give you all the prerotation you want and more.


Anyone for a jump start :D :D :D :D


Mike

[Mike Hook]

Now for all you pilots , if you had prerotation to the point of torque being a problem as you start your take off would not opposite rudder in the prop thrust line offset the torque??

Just something to think about.

Mike

[KenSandyEggo]

Here's another thought for the RAF and AAI that turn the clutch face off a pulley-belt behind the prop (on the crank)......or ahead of the belt, depending on your choice and which way you're facing. I started talking to someone about this awhile back, and we thought that since we don't have a rubber wheel against the prop belt, the main slippage comes at the faces of the plates. I believe some get slippage at the wheel against the belt. Instead of the simple wire cable, we thought that a hydraulically operated cable may put enough force to the plates where slippage would be nil. Does this sound feasible? If I could keep my clutch faces from slipping with hydraulic pressure pushing the moveable clutch disk, I can imagine the rpm I'd get when I crank her up to about 4500 engine rpm. Yikes! I'd be happy with around 200 though.

[Mike Hook]

Good thought Ken

If you used a slave cylinder like a clutch slave cylinder to push your clutch brake together with a master cylinder like on a front motorcycle with a reserve tank built in with operating handle you could get much more pressure.
Just figure the out put of the master cylinder and the out put of the slave cylinder as the forumla ( Force = pressure times cylinder area ) Figure the area of the master cylinder and the applied pressure and then the appliied pressure to the slave cylinder times the area and you will have the force on the slave cylinder. The larger the dia. of the slave the more pressure, to a point that you dont have enough travel as compaired to the flow from the master cylinder to offset the voulume difference.

Mike

[gyrodude]

I have a 503 Dominator which is David Seasce's first machine. It has a Wunderlich prerotator. It is driven by a flat plate mounted between the gearbox and the prop instead of the usual drum.
I use 22' DW's and 250rpm is easy. It will turn over 300rpm but holding it in one place is limited by the brakes. In a little wind the nosewheel will come off the ground spinning up.

[Neil Hintz]

We get 290 on 28' dragon wings here in NZ, Have a look at the unit on the NZ Dominator, mechanical. This is not to be use by the faint harted, there is a LOT going on at this rotor speed. rotor drive torque is signifigant and makes the stick heavy, brakes are hard on ( foot slips off one brake and your in trouble ) hard rudder, as you release the drive everything tries to go the other way. Lots of skill required!
I have a new unit underway similar but different, 6kg, softer engagement, same top speed. You will see on the web how short the takeoff can be, downloadable video.

www.autoflight.co.nz

[KenSandyEggo]

Visited Hammerhead today and Robert had already rigged up a crude prototype, just to test the basic premise out. It worked great! Check out the photo. ;)

[Neil Hintz]

It would seem you win!

[Aussie_Paul]

I give up, all that rrpm with the engine stopped. Ken, you are the man!!!!! LOL.

Aussie Paul.

[KenSandyEggo]

Paul, remember that I have 2 tachs and you're only seeing one. I figured one ignition was enough for the test. The blades spun up so fast that the water didn't even get a chance to warm up.

I'm hearing that having to rev up the engine is a problem as the brakes start giving. The thing with my setup is that I've seen close to 200 rpm on the "Blade-Whacker's" gyro with only about 1400-1600 engine rpm. My crappy brakes will hold a lot higher than that, well over 2,000 rpm, so I'm looking to attain higher rrpms without excess engine rpm. We'll see. We're going to try a hydraulic system first. I have the master and slave cylinders ordered and the install has already been figured out by Robert. He'll design the bracket for the slave and the actuation. In what we have in mind, it should be a very simple install, using only screwdrivers and wrenches, with no drilling or cutting. The hardest job will be running the tubing from the stick to the prerotator lower unit, and even I should be able to handle that.

[rehler]

Sure -flying at 130 MPH!

[KenSandyEggo]

Hey, Ken II...it's only around 8:30 a.m. here and I haven't even finsished my first cup of coffee. I can't figure out what your 130 m.p.h. is referring to. Give this poor boy a hint. My brain hasn't totally kicked in yet.

Aaaaaack! Never mind. I just looked at my photo again. I get it.

[KenSandyEggo]

Here's a pic of the stick-unit. I plan to take the slave to Hammerhead this week and see what we come up with.

[KenSandyEggo]

Took the slave over and it sucked, but I got a catalogue from a manufacturer and believe I found just what I need. Robert figured out the displacements of the master and slave and theoretically it should work great. I ordered one and should have it in a couple days. I'll then have to have a mount/bracket designed and machined. I have a rough idea, but need some advice on stress and pressures against the mount before I try one.

[Brent_Brown]

Steven that is what hte A/S 18 would do and do the rotorblades the same at a push of botton it all went back like auto pilot. I got to fly one with John Potter many moons ago.

[Neil Hintz]

The Airmaster can go to no pitch, but not my model. You want some thrust over the tail to counter torque from the drive to the rotor, this can be significant.

[TommyRust]

I have an Ivo in flight adjustable pitch prop on my Windryder. I feather the prop, stand on the brakes and the rotor goes to 230rpm. Add a little pitch and were are ready to go.

[KenSandyEggo]

Tommy, give us some more info on your prop! How do you like it and does it meet your specs? If you can give us some numbers through the adjustment range, that'd be great also.

[TommyRust]

Ken, I have only taxied and run up the rotors. As soon as I get checked-off. Which should be very soon I can give you some data. What type of info are you looking for?

[KenSandyEggo]

I was wondering how smoothly the pitch change worked and was wondering if you had the "constant-speed" module they offer. If you have a Subaru 2.2, the cruise RPM would be interesting. If not, I don't know how meaningful it would be to others with Soobs. I was hoping that you had another prop on there, flew with it and then changed to the IVO.

[TommyRust]

Ken, I have a 532. The change is very smooth. I have a button on my stick that I push for increased pitch and pull down to remove pitch. I have a wooden prop I'll try later this summer then I'll have a comparison. I'm still a neophyte in the gyro world.

[KenSandyEggo]

Thanks, Tommy. Looking forward to your future posts. Anyone else ever try the IVO in-flight adjustable prop?

[PW_Plack]

Ken,

Jim Vanek's tandem trainer has the NSI adjustable prop and a Soob 2.2. He says that after climbout, he can pitch it back to cruise at 3800 RPM with the throttle still at the climbout setting, and it runs much more fuel efficiently, and quiet enough to hear the rotorblades. This would only work on an engine with lots of low-end torque, but the NSI Soob is hopped up to 160 HP, so a milder Soob should have an even wider torque band.

The NSI prop uses two metal contacts against a commutator ring to get DC to the prop pitch motor, and they make an irritating, intermittent, high-pitched squeaking. Other than that, it seems to be a really nice setup, although probably considerably pricier than Ivo.

[Brent_Brown]

http://www.peroxidepropulsion.com/article/22
go to this web site and see what they have and this is with the blades at 4 degrees. I would like to see them do it at 1.5 degrees. I have e-mail them but no reply.

[KenSandyEggo]

Took the hydraulic slave to a machine shop that does R&D and he's going to make a mounting bracket for it. It's a little tricky, as I want to only use the one bolt that the spring is attached to for securing it. I came up with a pretty good idea for the mount that he liked. He said he'd call me next week to check it out.

[StanFoster]

Ken: Are you going to be marketing this pre-rotator if it works out? It would be nice to be able to pre-rotate to 200 .

Stan

[KenSandyEggo]

Those are my intentions if everything works out. I'd supply everything. I won't actually know if it works properly until the mount is made and all is assembled and tested. I have no clue as to price yet. Too many variables still up in the air. I bought all the components in "onesies" at retail. Once I have it tested and perfected, I'll post a little poll to see how many are interested and take it from there to see how much of a discount I can get on quantity.

The first bracket is going to cost around $200 for the prototype. The slave was around $100 with shipping. I haven't even priced the braided hydraulic cable yet, except for the 18"-er I bought to test the concept, because I haven't measured the full length needed yet. There are 2 AN fittings involved also. The hand lever with master cylinder was about $140 with shipping. So I have a lot to whittle down and some shopping to do for prices once I'm convinced it works well. Time will tell.

[PeroxidePropuls]

Hi Brent,
I did not recieve your e-mail.
I apreciate any comments and advice

[Brent_Brown]

I was thinking that this type of set up would win the PRA jump takeoff contest back in the 90s. From what I read you have the blades set at 4 degress is what right? If so way? You don't fly them like that do you? Iike I said above I would like to see the test done with the blades at 1.5 degress or at 0. If it is on a jumping gyro the blades would be at 0 for the spin up and them pulled to jump pitch and back to flight pitch. If used as a fix hub then set the blades at flight pitch and see what happens. I have to go back and read your work again but what PSI is used in the tank? 10 pounds for the system is not that much at all for over 300 RRPM.

My e-mail just said great work and some of the question I put in here.

Thanks for the work you have done so far I think it is time for this type of system.
Brent

[PeroxidePropuls]

Hi Brent,
The pitch is fixed at 4 degrees. It is supposed to fly like that. The tip rockets are powerfull enough to spin up the rotor without reducing the pitch. I am not trying to do a jump start, because the idea with a jump start is to spin up the rotor at 0-pitch (to reduce the need of power) and than return to a flying pitch of 3 to 4 degrees right at take off before the rotor slows down too much-is it not?
My idea is to keep the rockets going until you have enough forward speed from the propeller to keep the gyro up in the air. I think I can do a vertical start with the fixed pitch rotor in this way. Please advice if you believe I will kill myself (-just joking, I will be carefull)

The fuel pressure after the hand controll valve was 500 psi at maximum power output.

[Brent_Brown]

Erik you said, It can also be propelled with lower concentrated HP and an organic fuel.
What is the organic fuel can it be store bought? or do we have to make it?

[PeroxidePropuls]

Brent,
I have been running the rockets with a mixture of lower concentrated hydrogen peroxide and methanol (also called methyl alcohole). They worked fine for 20 seconds. This way of propulsion needs further development. The system also get a bit more complicated, because you need a glow plugg.
I strongly recommend not experiment with this fuel mixture if you dont know exactly what you are doing, because if you do it the wrong way the mixture may be explosive!
Monopropellant HP is safer and simpler. When the time commes I will do my best to supply you with the high concentrated hydrogen peroxide you need. I need some help from people that can help me with transport, distrubution and other things. I hope to find these people on this forum

[Brent_Brown]

So the glow pluggs are not needed and you have them on yours just to test the lower HP?

[PeroxidePropuls]

Yes, That is correct Brent. The glow-pluggs are not needed when use 81% HP as I do at this time.

[Brent_Brown]

What are the next test going to be. Was the 4 degree in the blade pitch just to see if it would left?

[PeroxidePropuls]

The next step is a real flight test. I do not plan to change the blade pitch. It is fixed at 4 degrees and it is supposed to be like that when flying the conventional way with small autogyros like the swedish Bumble Bee (Humlan in Swedish). What pitch angle are you used to see?

I started a new thread about this this morning, under "engines". I explain a little more about my thinking there. Shold we switch our communication to that thread?

[KenSandyEggo]

http://www.rotaryforum.com/forum/showthread.php?t=1404&page=1&pp=15

Go to this link in case you missed the info and pics that somehow wound up in the "Propeller" thread.

[KenSandyEggo]

Got my shortened cable back today and should hook it up and try the first spinup tomorrow. I won't do too much, because we have our annual hangar inspections on Thursday and I might have to do a little "house-cleaning." I should get done by 4 a.m. or so. :o

[Aussie_Paul]

WOW!!!!! Ken that is very keen. Hanger cleaning throughout the night until 4 a.m.!!!!!!!!!

Aussie Paul.

[KenSandyEggo]

Working on it until 4 a.m. would probably only get me to a "light dusting." It's a mess.

[StanFoster]

Ken: I am really following your pre-rotator progress. My single biggest complaint about my RAF is a less than satisfactory rotor spinup. Its not bad..but could 200 rpm ever shorten the takeoff roll.

When can I write the check to you? :D

Stan

[KenSandyEggo]

Write a check!!?? For what? If I get 200+ tomorrow, I don't have a darn thing to sell. All one will have to do is epoxy a good quality brake/clutch material to the bare plate and shorten the prerotator cable as much as possible.

Should it not quite make it, then the answer may be the hydraulic prerotator activation for added pressure between the 3 pucks and the clutch facing. I stopped in today to buy a new bearing for the lower prerotator housing and it's being worked on......or at least talked about.

[lanichol]

Pics of Ken's prerotator.

[LARRYEBOYER]

kENNY J, What was the final outcome of your hydrolic pre-rotor tests?

[lanichol]

240 rpm. He posted a pic of the tach somewhere in previous post.

[Timchick]

Is that a standard hydraulic brake master cylinder? What type of actuating cylinder did Ken use on the prerotator end?

[lanichol]

I am not sure. Need to ask Ken. I noticed he has not posted recently.

[Harry_S.]

I don't know nor understand why, one would go to the expense of trying hydraulics, electric, bungee cords or whatever, to get an additional 20-30 rrpm when pre-rotating. Takeoff still requires air speed and ground roll to get airbourne. If you only have a 500 ft. strip, for example, you're pushing the envelope as it is.

I have no problem at all with my stock pre-rotator. I would not fly into a strip that I thought I would have, maybe, a problem getting out of. ;)

You know...years back, there were no pre-rotators...other than your right arm. :D


Cheers :)

[Aussie_Paul]

I am not sure. Need to ask Ken. I noticed he has not posted recently.
....probably still getting settled in to his new location and has not been able to work out how to plug in the computor and turn it on!! lol :rolleyes:

Aussie Paul. :)

[lanichol]

Ken had posted his computer was cratered. So he is probably checking the conference at the nearest city library or some other temporary machine.

His post are very complete and probably doesn't have the time to write on the temporary machine.

As for pre-rotator, does not having a high pre-rotation speed decrease the drag to help accelerate on ground speed? It is very true you need the ground/air speed to get off the ground. I am only guessing as to the higher rotation in aiding acceleration on ground speed.

[Harry_S.]

As for pre-rotator, does not having a high pre-rotation speed decrease the drag to help accelerate on ground speed? It is very true you need the ground/air speed to get off the ground. I am only guessing as to the higher rotation in aiding acceleration on ground speed.

Your in the ballpark, Larry. My point tho, is the expense, weight, complexity etc. worth it?! For someone who is really hurting for want of a longer strip, the few extra rrpm for takeoff may indeed help him. But, you know...to each his own.


Cheers
:)

[Aussie_Paul]

.....Now don't be afraid!!! :eek:

The simplest and cheapest way, to have a reasonably short take of run, is to be able to pre rotate to 10 or 15 rrpm past the full power application without flapping the blades rrpm.

Regardless of the pre rotator rpm you still have to accelerate the mass of the gyro to lift off speed.

In my 130 hp Hybrid that rrpm is 170. With the 160 hp ej-25 it would be approx. 180 rrpm.

The question is!!!!! How much shorter, if any, will a pre rotated rrpm of 220 make take of run????

Aussie Paul. :)

[Coen]

If one can get enough RRPM so that full power can be given and then brakes released it will be good enough. So the principle being that any gyro being designed needs to have a prerotation system that can take the RRPM high enough that the pilot wont need to worry about flapping to much.

[Aussie_Paul]

Spot on Coen. With the stick full back the rotor thrust vector will help the braking scenario. You must have the stick all the way back by the time you get to 120 rrpm.

I see so many people pre rotate with the stick forward, then they release the pre rotator, bring the stick full back, and then apply power!!!

Coen, my thoughts are exactly the same as yours. As a minimum, you must have a pre rotator capable of comfortably attaining the minimum rrpm needed to allow a full power start to the take off run, just like a normal 2 seat fixed wing.

My aim is to achieve this with a soft start electric pre rotator.

Aussie Paul. :)

[Terry_Smith]

I think I remember an article in PRA mag quite some time ago (back when Air & Space America was still in Business) that they were coming out with a rotor head that would allow changing the pitch of the blades for jump takeoff like the 18A, but for 2 bladed rotors. Does anyone know what ever happened to that idea? I know all of the A&S plans etc were purchased, but I never heard anymore about the rotorhead. I think that a simplified version of the 18A jump ability would be a great addition to gyros. Just my 2 cents.

[Terry_Smith]

Oops - double posted.

[Chopper Reid]

Paul, I'm not sure that an electric pre rotator is going to spin fast enough .

[Aussie_Paul]

Paul, I'm not sure that an electric pre rotator is going to spin fast enough .
.......not sure? I am.

Doesn't your electric pre rotator get 170 rrpm in calm conditions!!!!:rolleyes:

Mine does!!:D

Aussie Paul. :)

[ahancock]

Is 170 rpm enough to prevent blade flap if you immediatesly go to full power?
Alan

[Aussie_Paul]

Is 170 rpm enough to prevent blade flap if you immediatesly go to full power?
Alan
....yes it is in a Raf 2000, or my Hybrid with 30' blades and 130 h/power. Actually in my Hybrid with 130 hp, 155 rrpm is ok when I am at MTOW.

The rrpm that you can go to full power will depend on type of rotor blades (heavy or light etc), the gross weight of the machine, and the HP/thrust available.

Aussie Paul. :)

[Adam H]

Paul,

I am also interested in using an electric prerotator for a gyro I'm working on, you say you get 170 rpm!? What set up are you using, what type of motor, ring gear and battery(s)? I'm used to getting 160-180 on my Wunderlich set up, I would be happy with 170 out of an electric.

[ahancock]

I'm using a Wunderlich with a 9" Air Command Drive drum. I get 160 at a throttle setting just above idle and can get 300 if I want it. I'm flying 22' dragon wings on a Butterfly with a Rotax 503. I have been prerotating to 250 and am curious as to how low I can go and still go to full throttle immediately. At 300 rpm, the nose comes up within 5 feet. At 250 it takes about a 75 ft run before the nose wheel lifts off.
Alan

[Adam H]

Paul, did you stop reading this thread!? You can't post those results with an electric set up and then leave me hanging without any details! C'mon, were living in a society here!

[Aussie_Paul]

Paul, did you stop reading this thread!? You can't post those results with an electric set up and then leave me hanging without any details! C'mon, were living in a society here!

Sorry Adam. I will reply in more detail later as I am running late.

The starter motoer is one designed for Custom cars withy big engines in smaller bodys. nThe starter motor is 50% more powerfull than the normal starter that we mostly use. The main hurdle is the soft start is the start up shocks will aklmost sheer the rivets off the ring gear.

'til later.

Aussie Paul. :)

[OzyRuss]

Hydraulic.........stay tuned

[Chopper Reid]

Paul, I only spin up to 100 revs due to battery longetivity .I do have a Odyssy battery and while they do a fantastic job, they are fairly pricey.

Russ, there's no doubt hydraulic is the way to go but keep weight and complex bits in mind !! The reason I like the electric stater motor is its so simple, only battery or starter motor can fail.

[Coen]

But i would be scared of using a electric prerotator since most engines nowdays r EFI and a elecric mulfunction will be bad, specialy if plane is to be used in the bush or outback.

[Adam H]

OK, Paul, you're not getting off that easy, I'm still waiting on the details of your set up. BTW, as for a soft start, what about using 2 6v batteries instead of 1 12v? You could start out with the 1 6v, just to get the blades moving, then kick in the other 6v. I don't know if this would work, any thoughts?

[Chopper Reid]

But i would be scared of using a electric prerotator since most engines nowdays r EFI and a elecric mulfunction will be bad, specialy if plane is to be used in the bush or outback.

Coen, I run an EFI motor and a electric pre rotator is all I have used !! My gyro lives and works in the bush. Along as you set it up correctly, you wont have any problems with it and my gyro has 3800 hours up approx!! I do carry a spare electric starter motor but thats it !!

[Aussie_Paul]

OK, Paul, you're not getting off that easy, I'm still waiting on the details of your set up. BTW, as for a soft start, what about using 2 6v batteries instead of 1 12v? You could start out with the 1 6v, just to get the blades moving, then kick in the other 6v. I don't know if this would work, any thoughts?

Adam, that is something I investigated. 6 Volt batteries are quite heavy and expensive, and if you always use one to initiate the soft start, that battery will end up well down on charge. They don't self level in series I am told.

One Oz gyro pilot has use a 6 volt 10 amp hour motorcycle battery for the soft start and then charged it with a 6 volt regulator from the main 12 volt battery. One problem with that is if you need to soft start again before the 6 volt battery is re charged.

I am going to try a slightly larger, 20 amp hour motorcycle battery, and see how that goes. I have several soft start systems I want to test. The main problem of sufficient rrpm with the electric pre rotator, I believe is solved.

Eventually we will have an option of a shaft drive to the bendix, but that is down the track a bit.

Aussie Paul. :)

[Timchick]

Adam, Do a search for "soft start" or "soft prerotator" and you'll find some threads talking about soft start systems for electric prerotators.