RunRyder RC
 5  Topic Subscribe
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 2240 views POST REPLY
03-31-2005 12:39 PM  13 years agoPost 1
darrens

rrKey Veteran

United Kingdom

My Posts: All  Forum  Topic

I am running a 15t pinion on the jazz/twist 37 set up with lipos and i was wondering if anyone had tried it on a 16t for higher head speed and with what results?
Alternatively, has anyone got experience of the Twist 33 on a 4s set up and can offer a power comparison to the 37 set up?

He who dies with the most toys is the winner!

PM  EMAIL  GALLERY  Attn:RR  Quote
03-31-2005 07:44 PM  13 years agoPost 2
Ben-T-Spindle

rrProfessor

Central Illinois

My Posts: All  Forum  Topic

A twist-37 is good for sport flying and learning basic 3D. If you use a larger pinion it will tend to overheat – some have even had magnet failure due to overheating.

The Twist-33 with a 14t pinion and the new TP4000-Pro Lite-4s2p is an incredible combination. Lots more head speed and power than the Twist-37/3s setup. Use a Kontronik Jazz ESC (it has a BEC that will handle up to 5s LiPo) and you will have a real winning combination.

This setup works best with a real good battery so if you get a cheap battery the performance will not be so good. The new 10-12C LiPo’s of about 4000 MAH is what you want.

... BTS

PM  EMAIL  GALLERY  Attn:RR  Quote
04-01-2005 12:56 AM  13 years agoPost 3
JoeR

rrApprentice

western NY

My Posts: All  Forum  Topic

B-T-S: isn't a 4000mah lipo a 2P pack not a 3P?

PM  EMAIL  GALLERY  Attn:RR  Quote
04-01-2005 08:44 AM  13 years agoPost 4
darrens

rrKey Veteran

United Kingdom

My Posts: All  Forum  Topic

Hi Ben,
Are you flying the 33 combo?

He who dies with the most toys is the winner!

PM  EMAIL  GALLERY  Attn:RR  Quote
04-01-2005 01:29 PM  13 years agoPost 5
Ben-T-Spindle

rrProfessor

Central Illinois

My Posts: All  Forum  Topic

Corrected the 2p/3p error!


I am flying a Twist-33, Phoenix 35, and SBEC. For the battery mount I am using a carbon rod and wood mount. But right now it’s down for a crash rebuild.


I have tried several battery packs over the past year and there is a big difference in performance – the smallest was an ET-2400 4s2p, which was lightweight but not 3D performance. There are a lot of battery combinations that work well for sport flying – I would not recommend anything smaller than 3000 MAH.

.

... BTS

PM  EMAIL  GALLERY  Attn:RR  Quote
04-05-2005 07:50 PM  13 years agoPost 6
sheva

rrNovice

West Harrison, N.Y.

My Posts: All  Forum  Topic

33 vs 37
The twist 37 w/ JAZZ 40-6-18 is a great combo and is recommended by robbe usa. I do not know how someone can can claim a lower head speed with a 37 vs a 33. This makes no sense. Unless you under power the 37 or the motor was burnt, and is now not putting out the power it used to, of course it will not give you the output you need. The batteries you are using should supply the current you need, and then some. This is just plain common sense. If you underpower a 3700kv motor, of course its head speed will be lower than a 3300kv motor. like all other power packages, the juice must be there for the motor, when it needs it. Otherwise it will get hot and struggle to do its job. I have checked with robbe on this issue, and they confirm my statements.
I have provided a link which go directly to the manufacturers website
One for the motors
kontronik
Second for the controller
jazz controller

The motor specifications state a minmum of 6-14 cells for this motor. If you don't provide the minimum requirements for cells, don't expect optimal performance.
Also the controller 40-6-18 will handle 40A continuous. The Twist 37 will draw max. continuous 40A. And surge 60A. If you are planning insane 3d then maybe you might want to think about a little more head room on the controller, for instance the jazz 55-10-32.
Its rating is 55A continous, 70A surge. Along with this you should keep in mind that the batteries must be able to file suit along with the controlller. Again, If your batteries can't keep up with the controller, then you will definately have problems. And possibly one big one called a crash.

Some brushless motors can be torqier than others(good example some outrunner motors), and usually the higher kv the motor the more you move away from torq, but a motor can still compensate for this, by putting out insane revs, which in the end would lead you, too not be able to tell the difference on comparable motors. It all depends on how the motor is engineered and its individual specifications. There is no blanket statement which applies to every motor out there. If I were to say so, then I would be full of it.

PM  EMAIL  GALLERY  Attn:RR  Quote
04-05-2005 08:43 PM  13 years agoPost 7
Ben-T-Spindle

rrProfessor

Central Illinois

My Posts: All  Forum  Topic

We are discussing running a twist-37 on 11.1v (3s LiPo) vs a twist-33 on 14.8v (4s LiPo).

.

... BTS

PM  EMAIL  GALLERY  Attn:RR  Quote
04-05-2005 08:47 PM  13 years agoPost 8
darrens

rrKey Veteran

United Kingdom

My Posts: All  Forum  Topic

Sheva,
You kinda missed what everyone else picked up on. As you know, every man and his dog who runs a twist 37 does so on 3s. As my post said "has anyone got experience of a twist 33 on 4s?". Yes I understand the differences between motors and from what I have read and suggested by others, the 33 with 4s offers more power and higher head speed on the right gearing, as BTS confirmed through his experience.
I am waiting for a member of our club to get his machine sorted on this spec also so will be able to offer a first hand experience once I see it for myself.

He who dies with the most toys is the winner!

PM  EMAIL  GALLERY  Attn:RR  Quote
04-06-2005 05:52 AM  13 years agoPost 9
sheva

rrNovice

West Harrison, N.Y.

My Posts: All  Forum  Topic

higher output
Lets forget about the cell count. What I am questioning is this statement made by BTS in response to your post, that the 33 will put out more power than the 37. Irregardless of the cell count. Please explain to me how you get a higher output from a motor with a lower kv. Because Unless there is some hidden magic here. A motor's KV is its kv. And I am not understanding how you can get more kv from a motor that has less kv. I do not belive this to be true. That is the point I am making. All I am asking, is prove to me how you can get more power from a motor that's output is supposed to be less. Just explain how this can be??? I am willing to listen.
This is how I view this problem in simple terms: you have two motors:
motor 1 is a 1 hp motor(actual motor rating)
motor 2 is a 1.25 hp motor(actual motor rating)

You are stating that motor 1 can generate more power than motor 2.
And this can happen by changing batteries and gearing.
These two things do not change the physical characteristics of the motor.
It would be like saying I can make a honda into a ferrari by changing the 12v battery.
This counters the facts.!
BTW: I am not mocking BTS, I am simply asking the question why?

PM  EMAIL  GALLERY  Attn:RR  Quote
04-06-2005 12:18 PM  13 years agoPost 10
TheRickster

rrApprentice

Beaumont Texas

My Posts: All  Forum  Topic

When comparing two motors with different KV and Battery Cell count the higher cell count is used to bring the lower KV motor up to the needed RPM..Granted If you ran the Twist 37 and the 33 on 3S the 37 would have more power..Possibly not becasue the 33 has the lower KV but because of the pinion you would have to use on the 33 to get the same headspeed you would lose a lot of mechanical leverage advantage becasue of the higher pinion tooth count.. But , if you run the 37 on 3S and the 33 on 4S you are running more Voltage on the 33 and so it will have more power..Anytime you can increase the Voltage and Aperage you are increasing the Watt's that it can deliver... It would be impractical to try to run the 37 on 4S because the RPM would be too high and you could not get a small enough pinion.(plus you might exceed the RPM limit of the motor).

From my understanding and experience this is the theory that HV setups are derived from..Plus using the higher Voltage and lower Amps the setups tend to run cooler and more efficient...

Rick

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
04-06-2005 01:20 PM  13 years agoPost 11
HugeOne

rrKey Veteran

Quebec, Canada

My Posts: All  Forum  Topic

Sheva,
Kv does not mean power, power is exprimed in watts. 3300 Kv mean that when the motor turn at 3300 rpm it will produce 1 volt, so at 33000 rpm it will produce 10V. When the motor produce voltage it counteract the battery until there is a small difference between the two. This difference divided by the internal resistance of the coil will give the current drawn in amps. The harder the motor work (rpm goes down) the greater the voltage difference the higher the current, if you stop the motor the current inside will raise to very high level. This phenomena is called "force contre-electromotrice" in french, sorry I don't know the english translation. So a lower Kv motor will need less rpm to counteract the battery or will need a higher voltage battery to stay at the same rpm than a higher Kv motor.

Raptor e620 w/V-bar, Tango 45-06, Phoenix 85HV, TrueRC 12S1P 4000mAh

PM  EMAIL  GALLERY  Attn:RR  Quote
04-06-2005 06:43 PM  13 years agoPost 12
darrens

rrKey Veteran

United Kingdom

My Posts: All  Forum  Topic

HugeOne/Rickster.....well explained

He who dies with the most toys is the winner!

PM  EMAIL  GALLERY  Attn:RR  Quote
04-09-2005 04:13 AM  13 years agoPost 13
sheva

rrNovice

West Harrison, N.Y.

My Posts: All  Forum  Topic

POWER AND MOTORS
A motor does not create any more wattage in otherwords power than its rating. This seems to be the point that I am not getting across with regards to my posts. However I believe it is an important point to get across. Because it will help others understand what swapping motors will or won't do. Yes, by changing gearing and battery combinations, due to the close wattage ratings of these two motors one can come close to similiar wattage levels. However, this is where it ends. They will never be the same. Unless the manufacturer has built in extra leeway on the amount that they rated the motors. I personally would not be willing to risk an expensive motor on a test like that. Asumming this, Then they should never be able to give more power than they are rated. As per the manufacturers specifications they recommend a temperature rating not to be exceeded. As some have indicated on other threads, there is a point to which a brushless motor says uncle, and gives up.
Power is a mesurement of work done, in our application rotational speed is the work ,rpm. The loads are the gear train, tail drive if main gear driven, the main rotor blades, and of course the aerodynamic loads. Many full scale helicopter manufacturers setup test rigs that model the larger blades and other forces to determine loads on there prospective turbine powerplants. And now with the advent of computers I am sure they computer model there loads as well.
When someone pulls a high load maneuver and claims there head speed goes down, and because of it, the motor is claimed to have sucked. There are alot of other things that can be a factor in this problem. High pitch , battieries, the helicopter itself. Or plain and simple doing maneuvers that exceed the capabilities of the the whole package.
Putting a dragster motor in a car doesn't make it a great car. It is the whole package that counts.

PM  EMAIL  GALLERY  Attn:RR  Quote
04-09-2005 05:08 AM  13 years agoPost 14
CustomPC

rrVeteran

Sydney, NSW - Australia

My Posts: All  Forum  Topic

I'm not sure i understand what you're saying but i understand it as follows.

Power is measured in Watts. It's power/watts that turns the rotor blades.
A heli of a given size will need a certain amount of power/watts to turn the blades at a certain rpm at hover pitch. At full pitch the watts required to maintain the same rpm increases substantially.

It's the ability of the motor/battery combination to produce the watts required and maintain those rpms that we are looking at. It's also good to look at how much is in reserve when the motor is producing 500W. I class reserve as how much higher can you go without exceeding the max volts/Amps of the motor.

For the sake of easy maths i'll use the eolo and round the figures at 200W for hovering and 500W for 3D aerobatics. In reallity they are a little lower.

Watt's is a product of Volts x Amps.

A high kv motor like the Twist37 running off 3 Lipo cells (11.1V)will use 21A current to produce 200W for a hover. To reach the required 500W for 3D the motor would draw 55A current and the rotor speed would drop by 10%. 55A is way over the Twist37's limits and would be punishing the batteries too. It can't safely deliver the required power without destroying itself and it has no power in reserve.

Next we have the Twist33 on 4S LiPo (14.8V). To maintain a hover at 200W it draws 15A and to produce 500W it draws 40A. The head speed is 400rpm higher overall and only loses 6% between hover and 3D work. 40A is just within the limitations of the motor and cells. The extra 400rpm of headspeed makes advanced aerobatics possible that you just can't do with the Twist37. The twist 33 could produce up to 570W so it has about 70W in reserve.

On to the HV setups running off 6S Lipo (22.2V). I'll use my current motor as an example, the Medusa 28mmx56mmx1900rpm. At 200W hover it draws just 10A and at 500W just 24A. Thats well within the limitations of the motor and Cells. Headspeed is as high or higher than the twist33 combo with only a 5% drop as the watts increases. There is ample power in reserve.

So, it is more efficient to have a lower kv motor running off higher voltage. The higher voltage produces more power and torque.

PM  EMAIL  Attn:RR  Quote
04-10-2005 01:01 AM  13 years agoPost 15
sheva

rrNovice

West Harrison, N.Y.

My Posts: All  Forum  Topic

Motor Specs.
Assuming a voltage of 11.1V for instance, lets take the twist 33 with its 35A constant current draw and round it off to 40A for Constant draw. Using P=I*V we calculate 40A*11.1V=444Watts

Then take the Twist 37 which can handle approximately 5A more constant current and 5A more surge.
Using P=I*V we calculate 45A*11.1V=499.5Watts

However if you were to leave the Ampere values the same, then the only difference would be 400rpm*11.1v=4,440rpm(that is motor rpm, not head speed) more on the twist 37 vs the 33.

Please prove to me how you can claim more power on a motor, that if you use same number calculations you get the same results, these are using the laws of electronics, which haven't changed in like 100 years. Assuming that the 37 won't choke at higher rpm, the head speed should be the opposite. It should be higher not lower. Forgetting about using various voltage battery combos. A base line should be established to compare these motors, not changing specs for one to obtain similar results from the others, for in fact if there is a difference in base line numbers then it will be the same for increase in values. This is how a hypothesis is drawn not random numbers plucked from nowhere.
Another thing to think about, is that a motor capable of handling more ampere would (assuming all things are equal) have more "head room","lee-way" than one which has a lower rating.(This is again assuming all things are equal).

In raw form the definition of Watts, is "A measure of power consumed or dissipated by an electrical component.".DEFINITION LINK , since the rpm difference is there between the 33 and 37 then the work being done, albeit a small difference,is more than the 33. Therefore the work being done by the 37 will always be more than the 33 at equal levels of current supplied and voltage. This is validated by the math.
No one has yet to be able to validate what they are saying, aside from if you do this, then this will be the result. The numbers don't add up to what is being said. If I am wrong, then please prove that I am wrong, don't guess or suggest. People have posted that the 33 will produce more power that the 37, please prove it, so I can go off and buy a lower powered motor, and expect more power than a highered powered motor. The facts just don't add up.

Also, brushless motors are more efficient at higher rpm levels rather than lower. You may ask why, well when the controllers have to actuate phase changes in the motor, there transistors or fets are on less of the time, less time on, means less heat, less heat means less loss of power, hence more efficient. And yes, higher voltage less current is going to be more efficent, since less heat will be produced and dissipated through the brushless controller.

PM  EMAIL  GALLERY  Attn:RR  Quote
04-10-2005 02:40 AM  13 years agoPost 16
CustomPC

rrVeteran

Sydney, NSW - Australia

My Posts: All  Forum  Topic

You are not seeing our point.

We have never claimed the Twist33 to be better than the Twist37 when both motors are on the same voltage (3S LiPo)

We are saying simply that a lower kv motor on a higher voltage equals the same rpms at less Amp draw and is more likely to be within the limits of the batteries and motors due to the higher efficiency.

The motors are doing roughly the same RPM's so the ESC is running just as efficiently.

Just look at larger helis that run large low kv motors on high voltages like 24-32 nickel cells and only require a 40A ESC.

Have you seen the KC spreadsheet. You can download it from the Electric Heli forums at RCGroups. It's an invaluable tool and will demonstrate what we are saying.

PM  EMAIL  Attn:RR  Quote
04-10-2005 02:47 AM  13 years agoPost 17
TheRickster

rrApprentice

Beaumont Texas

My Posts: All  Forum  Topic

"The Twist-33 with a 14t pinion and the new TP4000-Pro Lite-4s2p is an incredible combination. Lots more head speed and power than the Twist-37/3s setup. Use a Kontronik Jazz ESC (it has a BEC that will handle up to 5s LiPo) and you will have a real winning combination."


In the original post Ben compared the power of the 37 to the 33 with the 37/3S and the 33/4S.. Yes the cell counts where different between the two motors but the motors are different also.. As was stated the theory is to use a lower KV motor and use a higher Voltage to get the required headspeed and so with a higher Voltage more power will follow.. I have no scientific data to prove or disprove any of your theories but know what works and doesn't work..

Granted if we run BOTH motors on a 3S3P pack the 37 is the better choice BUT we are not talking about running them on the same pack..

The Aveox 27/39/1.5 is an excellent example of a motor that really would not even be considered for an Eolo but throw a 5S or 6S pack into the equation and you have a Rocket that most Nitro's would be jealous of power wise...Put the same motor on 3S and it would be a pooch....

Rick

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
04-17-2005 06:39 PM  13 years agoPost 18
darrens

rrKey Veteran

United Kingdom

My Posts: All  Forum  Topic

Seen my friend fly his Eolo today and he has just converted to a twist 33 and 4s. Wow, lots more "power" (I use this term for the want of a better term that would satisfy Sheva) and head speed when compared to a 37 with 3s. This thing flew and would compete with most 50 size machines. Following a 13 min or so flight the motor was just warm to the touch. I'm getting me one of these!!!!

He who dies with the most toys is the winner!

PM  EMAIL  GALLERY  Attn:RR  Quote
04-17-2005 08:51 PM  13 years agoPost 19
Ben-T-Spindle

rrProfessor

Central Illinois

My Posts: All  Forum  Topic

Glad to see that the Twist-33/4s is finally catching on. If I haven’t flow it for a while it still amazes me at awesome power of this setup. The best part is that the flight time is a lot longer than the Aveox/6s setup.

I really think that it’s inappropriate for anyone to comment unless they have actually seen it fly. This is one of those things in life that you have to experience yourself – it’s impossible to describe.

Don’t forget that the Hacker C40-9L has the same performance. This is a good alternative for all you that are burning out those Aveox motors.

.

... BTS

PM  EMAIL  GALLERY  Attn:RR  Quote
04-17-2005 09:17 PM  13 years agoPost 20
Lollo

rrApprentice

switzerland

My Posts: All  Forum  Topic

Just mounted a Hacker C40 14t 13s 4s2p pro lite , Hacker ESC and Helitronik 3A bec.
Great result, 2320 rpm, more power than 37, less RPM drop.
No heat
C40 13s has 3231 rpm/V

Hallo Darrens

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 2240 views POST REPLY
 Print TOPIC  Make Suggestion 

 5  Topic Subscribe

Friday, April 27 - 6:01 am - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online