Mast/Frame mounted pre-totors

[WHY]

Well have been doing a lot of snooping around the web for info on electric automobile starters and have come up with some interesting info and some questions. First, the info, found a unlikely source for information on starters and controllers, the guy's making the "battlebots" robots use a lot of starter motors for drive motors and do a lot of mods to them and have a lot of info on controllers and the many types there of, so here is another source of possible useful info.

Now for the questions, have come up with some ideas but do not want to re-invent the wheel so will post these question for all to read and reply to, maybe you can save me a lot of work and frustration, otherwise this is something I am going to have to find out because it sounds like it may have some good potential, and that is---mast or frame mounted starter motor pre-rotor.

This would require some extensive mods to the starter, but not unreasonable and could be made with out a lot of exotic machine work.

Looking at the Toyota/Subaru variety of starters that we presently use when head mounting the unit, it appeaars that the typical starter may be rated anywhere from 1.4 kw to 1.8 kw and gear reduced. Now upon looking around at some of the starters available from the speed shops it looks like you can get up to a 2.0 (or maybe higher ) kw units. I am not sure but I think a kw is about 1hp ??? if so this then is about 2 hp and with the torque from a 1 hp electric motor about equal to power of a 2.5 hp gas engine, this woud seem to be about the equivalent of a 5 hp engine------------maybe?

Now if all of these figures are some where near correct it would look like one of these HEAVIER and larger starters could really produce some rpm on the rotor "IF" it can be mounted somewhere other than on the head due to it's size and weight. It looks like all of the "super starters" are gear reduced with a solenoid engagement operating a oneway bendix and gear. If a bendix drive such as is presently used on the head is left there and the starter motor is connected via a flex shaft/ tubular shaft arrangement to the bendix at the head, then the solenoid engagement mechanisim, the starter bendix and starter gear could be removed and a direct coupling to the shaft(what ever kind you choose) and up to the head and the starter mounted somewhere on the mast or down lower on the frame. A soft start would be absolutely necessary for this arrangement since the torque from the motor is full power on contact and would snap,twist, or break any system used, perhaps even some form of centrifugal clutch could be installed at the motor.

I see two down sides to this, one is the starter weight and two is the battery size that will be needed, if you want power out, you going to have to put power in, ain't no free lunch. What say you ?????????

Tony

[Minnesota_Mike]

I like the idea of mounting the unit on the mast rather than the head. It allows easier balancing framewise of the weight issues (since you can move it to wherever).
I like a solid shaft drive using 2 u-joints
(per Chuck B. Lovejoy with needle bearing joints...not Pin Blocks). Install a Bendix similar to those used on the Wunderlich's on the Torque Tube (at the rear).
No gear reduction is how I would go (for max top speed) and utilize the slow start gizmo design thingy (seen on the forum somewhere that Dirtydog was working with) to spin it up without shock.

Correct...the weight of all this is heavy stuff...but if you have room in your "weight budget" for the battery and all...I say why not.

That thing would really torque around once completed.

[WHY]

Thanks for the comment Mike, can't help but think somone else has already thought or tried this and there is a big pit fall somewhere, that's why I made the post, hate to do it all over again if it's been tried and did not work out.

Tony

[Minnesota_Mike]

Hi Tony...
For most...they just have an issue with all the added weight...the battery being the stickler I'm sure. For some guys I've talked to it was the slow start gizmo...it sucks a lot of amp's since it's basically a resistor. My issue was wimpy u-joints...Chuck B. turned me onto the Lovejoy's.
I'm planning on using an old RAF shaft drive off a platter mounted on the redrive shaft- which is located above my EA-82.


M-M

[WHY]

Mike , on this thing I don't think I would use anything but a PWM controller it doesn't waste so much in heat and is more controlable but it eats the dollars.

Tony

PS i''m looking at this set up for my tractor ( although I already have a $650 single cyl 2 stroke that I bought for this purpose)

[WHY]

While looking around for info on real powerful starter motors I came across this site at www.jegs.com and found some really interesting stuff. First they have starters for hot rods and souped up engines and for diesels. The specs on the starters are not always given in the same way so it's a little hard to do a comparison, they have a starter for a deisel that produces 260 ft/lbs !!!!!!!!!!!!! and is rated at 2.5 KW for power and compression ratios of up to 18:1 but do not give a weight. Over in the gas engine department they have the Promaxi for the chevy #555-10040 and it is rated at 3 hp instead of in KW but gives a weight of 8.5 lbs and is rated for compression of up to 18:1 which would "seem" to be close to the diesel ratings although they do not give the torque rating like the diesel starter. At any rate these unit would have to use a excellent PWM controller or a centrifagul clutch in the system or they would make garbage out of shaft system and maybe torque the mast or check plates, for sure they are going to spin the HELL out of the blades.

The mounting blocks are machined from billet alluminum which means they are removable and therefore could be replaced with a custome machined unit since you would not be using the pinion gear and the spraque clutch, just the end bearing and a new arrangement to connect a drive system up to the bendix in the head. It looks like you will still use the solenoid on the side for the high current contactor in it but would discard the engagement lever for the bendix. These unit go for around 250 to 270 bucks depending on model and make. If a centrifagul clutch can be added to these starters with out a great deal of machining, this is looking VERY good.

Tony

[Friendly]

Thanks for the comment Mike, can't help but think somone else has already thought or tried this and there is a big pit fall somewhere, that's why I made the post, hate to do it all over again if it's been tried and did not work out.

Tony

I did this with the KB4 to get it in the air right away. The electric starter is just a fast set up. I ran the wonderlich Bendix to 3/4 chromoly square tube for a telescoping drive shaft to the starter. I welded impact socket universals to the two ends for u joints. and a fast way to connect the shaft to the starter with out machining any parts. The system worked well as I already had electric start so it was just the weight of the starter. The disadvantage is soft start is a big drain on a battery and second the starter only revs a certain amount of rpm no matter what the hp. so the rotors only get up to about 125 to 140. This is plenty of rpm if you have an asphalt runway. But for grass you want your takeoffs to be as soon as possible due to the roughness of the field. Also for my gyro I was flying short rotors and I had to taxi a lot to get them to flying speed.
The transition to flex shaft was easy since I already had the flywheel and Bendix in place. I just had to make a drive drum for the prop and a bracket to hold the lower drive unit. Now 240 plus is easy to get from the rotors and I have increased the rotors from 22 to 23 footers

[WHY]

Hi Mark

You have made a good point about the starter"peaking out " before the blades get to a high rpm, I noticed that these starters posted they have reduction drives of around 4.4:1 instead of the typical 3.5:1 ratio, so it may be necessary to have a larger pinion gear at the rotorhead. As for the "soft start" using a lot of power, this would only be true if you are using the chrome wire resistor arrangement, a PWM will waste very little energy but cost quite a bit.

Hopefully someone here on the forum has some knowledge of these "hot rod" starters and can give some in depth infor on them. One other thing for sure, you are not going to power these starters with the generic garden tractor battery.

Tony

[Friendly]

Tony,
Those starters require lots of torque to turn over high compression engines with wild cams. The high ratios give them added torque over the standard starter. If you go with a larger pinion you loose the torque gained by the high ratio. The normal 12 starter with the addition of some extra volts will spin the rotors at a higher rpm. But if you are going to do that, then the ultralight electric starter that Georgi uses is a better setup than the brute power of static rotor rpm.

[Resasi]

Tony I have an electric start that was made for me by Nicolas/Aviomania. It is small light and compact.

As you say you don't re-invent the wheel but read this thread
http://www.rotaryforum.com/forum/showthread.php?t=19125&highlight=Worlds+lightest+prerotator

By the time you have a battery in my case two 12V batteries I had added 10 lbs however the batteries are very small and compact, in fact lighter than the single 13lb Oddessy they replaced.

It spins up the 23' DW's to about 125 static but then assists and accelerates them throughout the ground roll.

Have only just got the gyro flying so only two hours experience with it but it seemed to work very well indeed and I am very happy with it.

Nicolas was great to deal with and always extremely helpful.

[Dirtydog]

Resasi :
I have yet to see a price tag on the small prerotators that Nicolas/Aviomania are building. :noidea: I have asked but never got an answer......:tape:

I hope to get the rotor tach hooked up this week end to see just how fast mine will spin up to.

Anyone :
I have wondered about the uses of the small 12, 14, 24, and 36volt battery pack like what DeWalt makes it could be used some how? :noidea:

If you could hook 2 to 3 together and still keep it to the voltage you require, would the batteries hold to full rpm? :noidea:

I have seen the small 2 cycle weedeater engines on gyro's for a prerotator and wondered why you could not use a roller type wheel on a the flywheel? I don't like the idea of a chain or belt driving the system up there and coming loose to lock up in flight.:twitch:

I have one of the small engine that came with my sons scooter, the engine has a gear box built on it to give it more torque to start.


This what I have right now!
Don't know if i am going to happy with or not until i start flying.

[Alan_Cheatham]

..........I am going to have to find out because it sounds like it may have some good potential, and that is---mast or frame mounted starter motor pre-rotor.

Been done before and by Ron Herron on the LW-2, at least I assume there is an electric starter motor in the fuselage as I doubt it's hand-crank.

Keep in mind that what the prerotator is doing is feeding the rotor the horsepower it needs to get to a certain rpm so HP is the name of the game, torque alone is really irrelevant as anything can be geared to give the proper torque, even a mouse running in a cage. From experience you will need about 4.5 hp to get 23 foot Dragonwings to around 230-240 rpm.
.

[WHY]

Hi Alan

You mention 4.5 hp to get 23 foot Dragon Wings up to about 230-240 rpm, but here is where I wonder if the electric motor vs gas engine factor comes into play, I know you say that hp is what is necessary but I have seen the proof where a 3 hp gas engine was needed to do the work that a 1 hp electric motor did before. This may be due to the fact that a 4 cycle engine only produces power in 1 cycle out of every 4 cycles, the other cycles being exhaust, intake and compression. BTW could those be hydrualic lines up to a hydrualic motor on the head ?

Tony

[Friendly]

here is an old picture I had

[Resasi]

Chris I know that Nicolas has been extremely busy recently. The price I got was for a prototype under development, and I do not think he has finalized that yet.

He had been trying to give me a 12V system but I eventually went with the 24V though I believe he will continue experimenting with the 12V.

Your looks very compact, a big improvement over the one you began with.

If you read the thread you will see that the use of small power drill batteries was discussed.

[Alan_Cheatham]

Hi Alan

You mention 4.5 hp to get 23 foot Dragon Wings up to about 230-240 rpm, but here is where I wonder if the electric motor vs gas engine factor comes into play, I know you say that hp is what is necessary but I have seen the proof where a 3 hp gas engine was needed to do the work that a 1 hp electric motor did before. This may be due to the fact that a 4 cycle engine only produces power in 1 cycle out of every 4 cycles, the other cycles being exhaust, intake and compression. BTW could those be hydrualic lines up to a hydrualic motor on the head ?

Tony

HP is a measurement of doing work and is defined as 1 horsepower = 33,000 foot-pounds/minute and if tested on a dyno an electric motor with 1 shaft HP would equal a gas engine of 1 shaft HP, and visa versa. In both cases the electric motor and the gas engine are converting energy input into energy output but in a different form, the motor electrical to mechanical and the engine chemical to mechanical, and there is a loss in that conversion process. I can easily see how an electric motor can best a gas engine in HP when looking at energy-in vs. energy-out, but in the case of a prerotator application the main factor is going to be shaft HP.

The downside to any electric prerotator is the power source, the battery, and it itself is an energy converter of chemical to electrical, and not very efficient when looking at power output per weight.

I have the Littlewing video and Ron Herron does a walk-around showing the details of the LW2, it definitely is not a hydraulic prerotator but a flex shaft going to the head and looks to have a starter motor to me. (Note: the black tube on top of the fuselage is part of the rotor head roll control.)
.

[WHY]

Mark

That is one really sweet set up and vrey very close to what I am lookg for, I will just try to add a centrifigal clutch at the motor and using a 3 hp motor and what ever gearing is necessary to get the match I want along with a PWM controller.

Tony

[WHY]

Alan, you are for sure right that is a flex shaft and a starter motor mounted in the fuselage, again close to what I want to try on my tractor.

Tony

[freebird]

Just as a side note. 750 watts is approximately 1HP. Of course that can vary depending on the efficiency of the motor etc...

This is 550 lbf/s.

[Friendly]

Mark

That is one really sweet set up and very very close to what I am lookg for, I will just try to add a centrifigal clutch at the motor and using a 3 hp motor and what ever gearing is necessary to get the match I want along with a PWM controller.

Tony

Tony,
Thank you, it served its purpose well, I wanted to keep all the components as close to the center of mass as possible and I had intentions of changing to a mechanical drive at a later date, which I did.

I also think this is a good setup for an ultralight gyro. Extend the chromemoly to the keel and join it to a small gear box such as used on gas powered garden tools. A 90 degree, then attach a nice rubber drive wheel that can be retracted up from below the keel. When you want to prerotate, lower the wheel and allow the gyro to creep forward engaging the Bendix and starting the rotors to turn. As you increase the forward speed the friction wheel increases its speed and rotor speed. Just a thought, I just don't have the time to work on it with the rest of my projects and taking care of my mother.

[WHY]

Mark, Freebird, Alan

Thanks to all for your info input, Freebird,I was going to ask if someone could give a KW conversion to hp ( I could look it up but I get lazy sometimes) Alan did you ever know why Ron quite that arrangement on the starter drive? Alan on that set up you had on the mast, would you remember the kw rating on that starter and maybe the make and model of it, also how did you attach the "U" joint to the starter shaft ? This information is getting close enough to consider some investment to find out what I can do.

Tony

[WHY]

Well I guess I will call the post "CALLING ALL HOT RODDERS" past and present. The info I am now seeking is as follows, on the JEGs webb site they show a hi torque starter for a Chevy sb/lb, it is #555-10040 they rate it at 3 hp but give no ft/lb torque rating, I would like to know this spec. I would also like to know who makes this starter and where it is made, foriegn or USA and finally is the actual motor larger than the "standard" starter, that is to say is the armature larger in diameter, or longer or both. I am really interested in a increase in diameter size on the armature..

Surely out here in the vast world of gyro's there are some hot rod types also who could shed some light here.

Tony

[Aviomania]

Chris and others....

You may have emailed me before i finalized the price... i don't remember.... but since then i have emailed the price to people that were interested and we have 5 prototypes beeing installed.

The prototype is the manual model which will not be available when the production model will be released. The production model will be completely self diagnostic/ controlled for optimum performance. the manual needs some practice to operate for the best performance but its not hard.

Car starter prerotators are not very efficient and needs heavy batteries ( to be able to deliver at least 200A). A car starter with its battery weigh 2.5-3 times more than my system. add anything more on them.. like a clutch or bigger than 3 HP motor and is 4 times heavier... add an extended flex or solid shaft to mount it anywhere else than the head and is 5-6 times heavier.

My system is 3HP (2.85 to be exact) weighs 16 lbs with the cheap batteries ($40-60) or just 9 lbs with the expensive batteries.
The batteries are charged in flight and can be used to start your engine if it has electric starter and /or power your instruments/ radio.

the price for the prototype is 650 euro ($920) shipping is 65 euro anywhere in the world ($92 and its a 5 days delivery with insurance).
The Production model will be 950 Euro ($1330). an upgrade from prototype to production will be available for 200 Euro ( $280).

If you check the prices for motors, controllers, ring gears, Bendix etc. it will cost you more to make it your self.
The only way we offer these prices is because we make everything in house (ring gears, electronics, and all other components and get bulk quantities in motors which we convert and assemble here.)

I have a 5.5 HP model but it only gives 25 static RRPM more than the 3HP model, Accelerates the blades faster and the take off run is 5-6 meters (16-20 feet) shorter. the cost is 400euros more (~$550).... which i thing it does not worth it since you can take off easily from 70-80 meters (230-270 feet) with the 3HP and no wind (the distance can by as short as 55 meters depending on set up and pilot skill).

This is as an information for people that think they can get 250 RRPM with 4-5 HP.......You can not!!!!.

I have to run..... i am very buisy..... to many thinks to do!!!!!

[John Stahl]

Thanks for the update Nicolas. I have been checking your web page looking for your prerotator. I for one am looking forward to getting one or two for my gyros.

[Dirtydog]

Aviomania :
Thanks for the update I have been wondering for a while now how much you would charge for them and what the top RPM's were going to be.;)

I didn't have a chance to install the Schwinn tach to my bird yet I was changing out bolts to make sure I have at least 3 threads :wacko: showing last night trying to get ready for my inspection. I am wondering just how fast my Elect. prerotator is going to turn mine up..... I will have it done tonight.......:D

[Resasi]

Look forward to seeing how it works out Chris.