Price of Astro RC motors

[markz]

Just reading an artice
What a statement to make,

Astro motors are 80% motor and 20% toaster oven.

I will have to do a search and see if there is, or if anyone has done a liquid cooled version!
Maybe pouring water over some custom made fins.

I didnt realize they were so expensive.
What makes them so expensive?
I always thought it was the gear reduction that cost a lot, I figured the motors themselves were under a few bills ($200).
When I think of RC motors I think small motors. I didnt think that the Astro's were huge!!!

all considered industrial sized motors offering incredible power to weight ratios at a price:

3220 Astro - $695.00 8 lbs for racers and hotrodders 9-HP (6700-Watts) @ 95%
3215 Astro - $560.00 ?lbs
3210 Astro - $470.00 4lbs
3205 Astro - $415.00 2lbs

The smaller Astro 3205 is a safe and sane motor which will fit in the palm of your hand and keep you under the street-legal limit of 750 watts of power for your E-bike, while still having a reasonable speed of 25-mph without pedaling.

When you look at the Astro motors, these all have the same diameter of can, and the various power levels are achieved with additional length. The 3210 is twice as large as the 3205, and the 3220 is twice as large as the 3210.

I love the videos at the end of the article, burn outs on the 3220 motor on the trike is amazing.

The noise is still too loud for my liking. But what a powerful awesome motor those Astro's are!

 

[Thud]

I didnt realize they were so expensive.

these motors were developed for government contracts early in the unmanned aircraft days....before they were called drones.

The power-density & operational envelop are tough to argue with...samarium cobalt magnets keep turning out power long after reaching the curie temperature of a neo magnet. until you roast off the 200+c wire insulation the motor will perform. You can really abuse them if your willig to learn the limits & apply proper gearing practice.

why do they cost so much? american made parts from mill spec. materials....I don't know if all the stators are wound in mexico any longer...but I suspect most are. & I think they can sell all they make to their "big" customers....rc aircraft & e-bikes prolly don't create a tick on their annual sales graph.

I always loved their chargers & field equipment in my NiCad fueled rc days.

Recumpence has a direct relationship with the new & previous owners, doing some contract work for them when it is mutually beneficial. His builds really show the potential of these motors.

 

[recumpence]

I make fan cooled versions of astro motors. I also make liquid cooling sleeves for these motors.

They do not run very hot unless you beat the crap or of them. Not sure why the statement was made that they are 20% toaster oven. That is a statement born out of ignorance not reality.

Matt

 

[markz]

Where is most of the noise coming from, the gear reduction or the motor itself?

 

[Thud]

80% motor noise.

Trapazoidial comutation creates noise in the windings. Since coils are essentially speakers (without an amplification cone) the motors make ellectronic noise.
The controllers use this effect to create the arming signal tones you hear when you power up.

In my experiance, no rc set up is as loud as the video's would have you believe. Something about the resonate frequency seems to stimulate camera microphones. After that there is drive line generateted noise,

My outrunners also suffer from air-shear noise as they increase in rpms....adding a cooling fan amplifies the effect. Bolting the reduction to frame also turns the entire structure into a resonator at diferent frequncys. Noise is everywhere.

The worst offender to me is the tiny drive sprocket noise....a 10t #25 @ 8k rpms sounds like a tin can with a handfull of marbles being shaken. Thus the last few drives Ive built resorted back to toothed belts for primary reduction. They are the tool for the job.

In my experiance, the tires on pavment noise drowns out the motor noise @ 25 mph....for the rider at least.

 

[recumpence]

I completely aree with Thud.

There are a couple more items to mention;

Outrunners (orbital motors), also have can resonation. The can rotates and (in most cases) is cantelevered. This cantelevered can resonates at certain frequencies. All brushless motors running these standard square wave controllers whine when they run.

In my case, the drives I manufacture use 5mm pitch toothed belts. Those belts also whine a bit. It is a pleasing whine sound, however.

The sound these motors makes is truly not intrusive at all. You can hear it when you ride, but most of the time the wind noise drowns it out because the motor sound is really low.

Oh, lastly, as for the cost of Astro motors, one major contributing factor is that they are hand made. Literally hand made. The cans are made on a lathe, the rotors are made by one man at a work station, by hand, the winding is done by hand..... Everything is done by hand.

One other item to mention, even though the military used to buy a bunch of these, I am currently the largest buyer of the 3220 motors. I dictate much of the specs of these motors (shafts, bearings, can configuration, etc) for bicycle use. So, they are specifically made for our application when I order a batch of them.

Matt

 

[motomoto]

Not sure why the statement was made that they are 20% toaster oven. That is a statement born out of ignorance not reality.

That was me making that statement. And yes, I am ignorant and I don't believe in reality. So there we are.

 

[jk1]

Astro motors are 80% motor and 20% toaster oven.

I think the reason for that 20% toaster oven is a valid point because yes its a good thing the motor and internal can handle 200c , but the question is why would you run it that hot as it significantly reduce the efficiency of the motor.

All motors have copper winding so every degree of heat causes the temps to increase and hence resistance to go up which reduce efficiency. Compared to a normal bigger motor that runs average winding temps of 80 deg to one that has 160 deg avg temps i.ce astro that's a few 2-3% points less efficiency.

Instead you could use a normal style motor that is a bit bigger and yes heavier or vent a normal motor with air cooling.

The other main negative of Atro motors for ebikes is that their RPM is a lot higher then needed and in most cases for a mid drive you would need 1 extra stage of reduction which add 3-5% efficiency losses of the drievtrain.

So combine these two things and its not such a good motor for an ebike after all, you can see it discussed in this thread that the 1680w cyclone motor probably has the same or more efficient on an ebike with similar weight... I guess this makes sense as the astro was optimised for ultra light weight in a plane use which is not what an abike is....

https://endless-sphere.com/forums/viewtopic.php?f=30&t=65757&start=350

 

[recumpence]

Astro motors are 80% motor and 20% toaster oven.

I think the reason for that 20% toaster oven is a valid point because yes its a good thing the motor and internal can handle 200c , but the question is why would you run it that hot as it significantly reduce the efficiency of the motor.

All motors have copper winding so every degree of heat causes the temps to increase and hence resistance to go up which reduce efficiency. Compared to a normal bigger motor that runs average winding temps of 80 deg to one that has 160 deg avg temps i.ce astro that's a few 2-3% points less efficiency.

Instead you could use a normal style motor that is a bit bigger and yes heavier or vent a normal motor with air cooling.

The other main negative of Atro motors for ebikes is that their RPM is a lot higher then needed and in most cases for a mid drive you would need 1 extra stage of reduction which add 3-5% efficiency losses of the drievtrain.

So combine these two things and its not such a good motor for an ebike after all, you can see it discussed in this thread that the 1680w cyclone motor probably has the same or more efficient on an ebike with similar weight... I guess this makes sense as the astro was optimised for ultra light weight in a plane use which is not what an abike is....

https://endless-sphere.com/forums/viewtopic.php?f=30&t=65757&start=350

So many "Facts" are thrown around, but the truth is found in the specific setup and application.

For instance, a 3220 can be wound to run at 14,000 RPM (or a touch higher) and peak at well over 90% efficiency at 8,000 watts continuous with a peak output of over 16,000 watts (at lower efficiency and only for brief periods). However, at that RPM, reduction losses do build up. Also, if you want to run that super high RPM motor at a lower RPM (lower throttle setting) for cruising, you will lose efficiency because you are running the motor so far below its efficiency peak. Now, you can also setup a 3220 with higher turn count (lower KV) and see extremely high efficiency. But, with such a low KV, peak power is sacrificed. So, you need to balance your need for power with your need for efficiency.

Asking what motor is perfect for a bicycle is like asking "What is the perfect house?". Well, is a basement important to you? What about a garage (got to have a garage). A gated community? What about a split level? Cape cod? Hmm, maybe a ranch with an attached garage would be great....... It all depends on your family's needs and your preferences. It is the same with our project bikes. Are you looking for ultra light weight? What about huge horsepower? Hmm, long range? What about cost, ease if installation, reliability, etc, etc, etc.

There is no "Perfect" (or ideal) E-bike motor. One motor choice or another may best suit a given task. Astros might be good for one person, a Bafang would be good for another, and a Cyclone for another person. It all depends on your specific requirements and goals.

Matt

 

[tangentdave]

They do not run very hot unless you beat the crap or of them

Truth.

These are nice motors. They are doing so much work in such a small space I'm amazed they only get hot to touch with how I ride them. They can take a lot of abuse, without damage.


-dave

 

[Punx0r]

A motor designed to cope with high temperatures doesn't necessarily mean it will be run at those temperatures. It make it more reliable when run at more normal temperatures (greater safety margin) and more resistant to abuse.

Also, despite the reduced efficiency at high winding temperatures, continuous power output might still be higher because while the motor is creating more heat from greater copper loss it can also shed more heat because of the greater difference between motor temperature and its environment (effect of delta-T on rate of cooling).

I've never heard Astroflight motors called anything other than high quality, high performance motors