WIRE DRIVES

[Charles Perdue]

The reason that I chimed in on this thread was to avoid misinformation being spread as fact. When I post it is from experience and fact, NOT OPINIONS.

The wire drive used behind nitro motors is a COMPLETELY different animal than when it is used behind an electric motor.

Charles

 

[hugh hargett]

How so charles? And im not speaking from opinion Im speaking from what I run. Im not here disproving or proving anyones theories im just stating what has worked for me. In actuality I think electrics have more instantaneous torque, but tell me how does the wire know the difference really? Nitro or electric all we are working with is rotational energy. The physics acting upon the wire should be the same nitro or electric. Im not sure I understand you :huh: . Also what "misinformation" are you talking about? I quoted you agreeing with you on the aspect that the cable jumps around if not kept in check by a support of some kind. if youre talking about the set screw thing... 1 you must understand we are not talking about the same thing 2 I have run a wire collet with 2 sets of oppossing set screws on .078 wire and it hasnt slipped once on 4.5 hp @ over 30k, but thats not even what I was speaking of when I addressed marty. Just because mine didnt slip doesnt mean that your didnt so for you and you experiences the pressure type collet would be the ticket. The end I was talking about was the motor end and I can tell you I know it wont slip. If youre not sure exactly what Im talking about I will show you a picture. Lastly like your motor analogy with the bearings Ive built several high performance 4 cylinder turbo motors and I know that motors that have wider bearings on the crank are more desireable for pressure playing. No harm no foul Charles I was only giving my experiences like everyone else.

Gil I dont like ceramic bearings as they are designed to deal with heat not side load and they never worked that good anyway at least in turbos they sucked. In a wire drive set up where side load is a concern i'd definately rather have a steel sealed bearing.Ball hardness is important when you have alot of side load

Here again just my opinion please dont be upset.

Charles this is a great thread if you have a concern please pm me. We cant hash it out here though. I dont really know what I did wrong.

Cheers

Hugh

 

[Charles Perdue]

I understand exactly what you are saying. What I am saying is that with an electric motor the power application is constant, with the nitro motors, the power application is applied to the wire in a VERY STRONG pulse (power stroke). What this does is, a twisting of the wire combined with the curve of the wire, the wire tries to straighten out, this sets up a harsh vibration (harmonics) that can be heard as the boat is running, on the table and on the water. If this characterestic is not compensated for in the design, it will cause the wire to break or come aloose. A support bearing or bushing located 1/2 way along the wire will effectively double the RPM at which this takes place therefore moving the harmonics out of the range in which the drive line is turning. This bushing/bearing has to have a very minimual clearance to accomplish this. Running a 3/32 wire in a 3/16 tube is not even close.

As for the drag of the center support, a bearing or bushing is a lot less than the wire contacting the stuffing tube over several inches. Another reason for using a large (1/4 id) stuffing tube is to allow the engine to move around on its flexible mount without the wire contacting the stuffing tube. ANY CONTACT builds up heat very quick to the point of removing the temper of the wire, when this happens, the wire will only want to flex at this point alone, causing almost instant breakage.

This is information that I learned in developing the wire drive used with the NITRO engines over a period of many months.

Charles

 

[hugh hargett]

I would say that an electric motor has a huge instantaneous pulse when you nail the trigger from dead stop and a nitro has a power band that for one its already spinning when it his the water and before it gets into the band so the change in acceleration is not as abrupt with the nitro. So on that note fundamentally I disagree. I dont run any nitros now other than cars but I have plenty of my own exposure to nitro motors. One thing I do know is our debate only encompasses a few things that are going on so its hard to have a head to head debate unless we disect it all with a microscope. I will concede that maybe the vibration of your nitro motor itself causes resonance in the wire but Ive run my way for two years, and my drivelines are quiet in and out of the water.If you look at the sites that sell wire they almost always offer you teflon to go with it. I bet you dont use teflon. You may say it melts then siezes everything. That has happened to some but has never once happened to me. I run flexes without teflon but I like to use them with wires. In no way am I any expert or anything I am only telling you what works for me.In that reguard alone its not misinformation; if I use it and it works. You or I have no way to know which way is really better without creating a test with controls so, no reason for anyone to get upset. Charles heres one other thing to consider if the races of the bearings arent snug on the wire bearing or not it will create some funky harmonics; the same thing applies if the bearings arent set snugly in place in the strut via pressesd fit, loctite or something.I do still believe that one can be "OVER-BEARINGED" lol.

Again charles not at all am I saying youre wrong. Fundamentally; I just think were looking at it in different ways.

im always willing to learn

Hugh

 

[Charles Perdue]

Like David said, you can lead a horse to water but you cannot make him drink.

You are still talking about an electric motor on a wire drive. I am not talking about an electric motor, I am talking about a NITRO motor on a wire drive.

I am thru with this thread. At least everyone that reads this can make up their on minds as to what is fact and what is speculation.

Opinions are not facts.

CLASS IS OVER.

Charles

PS Just curious, are you by chance a politician?

 

[hugh hargett]

Yes sir. Have a good one fellas.Again Charles sorry we couldnt meet at a more nuetral point on this topic. The reason I felt I could speak is because this thread started with gil making references to the wire being run by fe guys, which I am. From reading it was quite clear that some of the nitro guys have never run wires .Luckily you have. I do believe that some of the info I gave was useful for those who choose to accept it. Those that dont like my way of thinking thats fine too. I hope the next time we talk no one has to get mad or anything. I also learned alot from you to admittedly and if you go back and read you will see where I supprted your way of doing things. We only disagreed on a few aspects so again Mr Purdue Im very sorry you took it the wrong way.

sincerely

hugh

 

[hugh hargett]

Marty, I dont see any reason why this wont hold:

Have a good one .

Hugh

 

[hugh hargett]

Gil did everything work for you?

 

[gil sonsino]

Hugh haven't had too much time for these tests but I see no reasons to not work.....will let you know in a few days.The only problem now is that I changed the motor for a big one the Turnigy PRO COMP 1700kv with 8mm shaft so probably I wll have to change the wire to 5 or more milimeters.This motor is used for 1/5 scale boat or car and is a monster one!

Thanks

Gill

 

[hugh hargett]

Gil I'm trying charles's method of three bearings and silver solder insted of loctite and I have to admit it virtually removed all end play and is very quiet and smooth sounding. I will get it wet sometime this week and post some video.

hugh

 

[hugh hargett]

Hugh haven't had too much time for these tests but I see no reasons to not work.....will let you know in a few days.The only problem now is that I changed the motor for a big one the Turnigy PRO COMP 1700kv with 8mm shaft so probably I wll have to change the wire to 5 or more milimeters.This motor is used for 1/5 scale boat or car and is a monster one!

Thanks

Gill

Gil 2mm wire should survive it though .092 might be better there also .125 no ones tried that that I know of . I eld some and to my surprise it wasflexible. Id like to weight a segment of it as compared to flex cable.

 

[hugh hargett]

Hey gil read this article fully http://www.fastelect....net/drives.php . talks about the drag of bearings under water and about high heat solder on a wire. Tried all those bearings and as I originally thought that isnt the way to go in a strut. That extra support is at the cost of rpm. In lead the shaft floats underwater.

 

[gil sonsino]

Nice article.

Thanks

Gill.

 

[tnrcboatracer]

ON a nitro motor, you need to consider the variation in angular velocity. The electric motors have instantaneous torque, but once running the power pulses are several per revolution based on the number of poles on the rotor. In nitro it is one pulse per revolution, period, The variation in angular velocity on a single cylinder nitro motor is quite large. The velocity is highest just past TDC, and starts to slow by 135 degrees or so. After 180 degrees, the velocity is slowing a bunch. until the next ignition cycle. Kind of like a jackhammer on the shaft. The nitro is much more severe than an electric, just look at the bearings in a nitro motor, and how nong (or short) they last.

 

[hugh hargett]

Yes but that jackhammer force your talking about isnt placed on the shaft in the strut its placed on the crankshaft in the nitro motor.

 

[Charles Perdue]

Jon, you have just wasted your energy typing. I do not believe that you can lower yourself down far enough to his level to make him understand that he does not have a clue as to what he is talking about.

Charles

 

[tnrcboatracer]

Charles, I'll try one more time because I don't like to give up. I need to call you to ask you a question about your strut BB's

Hugh, The jackhammering I am talking about is due the to angular acelleration of the crank shaft during the firing cycle. It is torsionally applide down the length of the shaft. The electric motor applies torque relatively smoothly in torsion, The torque power pulse of a nitro motor is only a fraction of each revolution. This torsional vibration is what sets the nitro motor apart from the electric motor.

 

[Norm Doerr]

Charles, I'll try one more time because I don't like to give up. I need to call you to ask you a question about your strut BB's

Hugh, The jackhammering I am talking about is due the to angular acelleration of the crank shaft during the firing cycle. It is torsionally applide down the length of the shaft. The electric motor applies torque relatively smoothly in torsion, The torque power pulse of a nitro motor is only a fraction of each revolution. This torsional vibration is what sets the nitro motor apart from the electric motor.

Yup....this is very true.

Also the prop is loading an unloading numerous times per engine stroke less with more blade more with just two blades.this is why a lot of very technical boaters would index the prop with the stroke of the engine, (back in the old days).

Lots of stuff going on with a single cylender two stroke internal combustion engine hooked directly to the prop via some sort of shaft. Even more complcated with a wire or flex cable.

 

[Michael Caruso]

Thanks guys it's time to roll over the sleeves and start new things.

Gill

Gil,

Nice website I wish it was in English. I too have raced RC boats since 1972. I am not racing so much as learning about everything all over again. I love your White rigger. I started last year with a little Aquacraft Revolt stock motor, ESC and Grim 4s battery trimmed and an Octura X-637 it goes 52 mph and a ton of fun. Really want to run SAW but have much it learn.

Mike

 

[gil sonsino]

Thanks Mike for the nice words and I'm in process to get my FE rigger now with a Neu motor ready for tests in one week...will post a video.sorry to not have the page in english but you can use a good translator too. Gill