7 replies to this topic

[Hionimi]

Hello, I'm looking to upgrade my Stryfe as my first upgrade project, picking the parts isn't the issue, except for the motors. It seems hard to tell what specifications are actually ideal. I read a lot of people saying the RPMs needs to be high, but I wonder, isn't torque more important? I imagine higher RPM would also eventually be pointless as it just makes the darts slip more and perhaps even wear them out faster rather than just shooting them faster.

I have my eye on the Tamiya Hyper 3, it features 1.9mN-m and 21,200 RPM at 3.0v, but also a draw of 3A... I guess this is multiplied with each motor added? (So in Flywheel Blasters it would end up drawing 6A?) I fear the high draw would not only mean replacing all the wires with lower gauge ones, but also replacing the switch(es). In another topic I read someone speculating the switches can only handle up to 2A...

Also, I hear some people saying Tamiya engines aren't any good, if this is true, what engines would be good then? I'm looking for just 130's as I'd rather not cut into the shell.

Another thing I need to add is that I live in the Netherlands, I could buy from e-Bay though I don't know what the taxes might do with some products, they taxes they tend to add are just not funny anymore and even make it more appealing to buy stuff from local hobby shops and actually get some decent warranty too while I'm at it. Of course that means brands like Tamiya are easier.

[MAV13]

There are better Tamiya motors than the Hyper 3 for Nerf applications. The Torque Tuned, Mach Dash, and Plasma Dash are the 3 I have seen used before, listed in increasing order of performance. You are correct in thinking you will need to replace the rev switch with something rated higher, as well as the wiring. If you do choose to use Tamiyas, your only choice for battery is a 1S Lipo (3.7V), alkalines and most other chemistries won't work unless you get a pack custom made. Tamiyas will get good performance in a Stryfe but they aren't the most durable motor, and they wouldn't be good in a blaster like the Rapidstrike.

If you want to go another route, these motors on eBay are well tested and reviewed by the community, in the absence of the out-of-stock Falcon 130 motor. They will net better durability and performance than a Tamiya in most cases; these will need a 2S Lipo, but will also work fine on IMR cell batteries, unlike high-end Tamiyas.

Edited by MAV13, 16 July 2015 - 05:56 PM.

[jwasko]

Hello, I'm looking to upgrade my Stryfe as my first upgrade project, picking the parts isn't the issue, except for the motors. It seems hard to tell what specifications are actually ideal. I read a lot of people saying the RPMs needs to be high, but I wonder, isn't torque more important? I imagine higher RPM would also eventually be pointless as it just makes the darts slip more and perhaps even wear them out faster rather than just shooting them faster.

I suggest reading the paper linked here.

You are correct that, eventually, higher RPM is meaningless. That being said, you want something spinning faster than 25,000RPM. Of course the more voltage you put on a motor the faster it spins...until the motor burns up. Tamiyas usually don't stand up to additional voltage.

You need a minimum torque I suppose to be able to spin up the flywheel and then launch a dart. I'm not sure what that minumum might be, but the higher the torque the faster "snap time" you will have (accelerating the flywheels from 0 RPM to full speed) and the faster you will be able to shoot ("rapid fire" more rapidly).

The motors that MAV13 linked are some of the best cost/benefit ratio on the market right now and, as he said, many people like them quite a bit.

You could also try buying Blade 180s or Extreme Pro 180s but those are about $10 per motor currently. They are regarded by many as just about the best motors ever with 32,000RPM and 42mN-m of torque at 7.4volts. They eat up about 3.8amps (just spinning at max speed).

When planning a power source/battery, note that any motor will draw a lot more current when the motors are stalled. For instance, the aforementioned 180s go up to 22amps!

Edited by jwasko, 16 July 2015 - 08:04 PM.

[Hionimi]

If you want to go another route, these motors on eBay are well tested and reviewed by the community, in the absence of the out-of-stock Falcon 130 motor. They will net better durability and performance than a Tamiya in most cases; these will need a 2S Lipo, but will also work fine on IMR cell batteries, unlike high-end Tamiyas.

You could also try buying Blade 180s or Extreme Pro 180s but those are about $10 per motor currently. They are regarded by many as just about the best motors ever with 32,000RPM and 42mN-m of torque at 7.4volts. They eat up about 3.8amps (just spinning at max speed).

When planning a power source/battery, note that any motor will draw a lot more current when the motors are stalled. For instance, the aforementioned 180s go up to 22amps!

IMR's and Ultrafires aren't easily available where I live, but I also prefer to use Li-Po's. I know they can deliver seeing as I also worked with model airplanes and multirotors. (I actually wish I could use Brushless outrunners but that appears to be really tricky, but I read you could use their bell as flywheel though!) And 42mN-m for 180!? That's quite a different story! 180 Are more powerful, though again, I hope to stick with engines that fit inside the blaster without needing to saw into the shell. I'm still curious what the torque specs are on these motors MAV13 linked or the 130 Falcon's.

Also, reason why I picked that one Tamiya is that it actually states it has Carbon brushes, picked up somewhere that Metal brushes are generally not a good pick, that correct?

[MAV13]

Lipos are miles better than Ultrafires or IMRs so definitely stick with that. And yeah, carbon brushes will last many times longer than metal brushes. Both Falcons and the motors I linked are carbon brushed, as are the 180s mentioned.

I know Falcons are 240 g*cm stall torque, which is roughly 24 mN*m; more than adequate for basically instant startup but obviously less than a 180. The Falcon motor is great but it is currently sold out EVERYWHERE online. Some aussie nerfers are putting in an order direct from the chinese manufacturers for new ones, so those should begin to spread soon.

[Hionimi]

Wasn't that the MTB group or something?

This one? (Links to Youtube.)

Edit: I actually noticed another engine in the post jwasko made, in the guide by rhino-aus, the NSR 3005 Shark, crazy specs that one has! My only concern is with engines that reach such a high RPM (40,000), do get that torque of 210g/cm over a wide range or only at that RPM? If the latter is true, wouldn't an engine achieving 30K-35K RPM and 210g/cm torque be better suited than one that does 210g/cm torque at 40K RPM?

Lastly, these airing holes, they're there to cool the engine, but they're likely covered by the flywheel case, wouldn't this give issues like melting or at least warping the plastic?

Edit 2: Checked some videos on the NSR Sharks in a Rapidstrike... Those things are scary at 11.1v... Think I'll stick with 2S1P, found a nice pack (links to Hobbyking) too that can be fitted inside the Stryfe's original battery compartment with some modding, it's almost 1,000A and delivers 25C, 50C in bursts, so moooore than enough.

Edited by Hionimi, 17 July 2015 - 03:03 AM.

[rhino-aus]

Wasn't that the MTB group or something?

This one? (Links to Youtube.)

Edit: I actually noticed another engine in the post jwasko made, in the guide by rhino-aus, the NSR 3005 Shark, crazy specs that one has! My only concern is with engines that reach such a high RPM (40,000), do get that torque of 210g/cm over a wide range or only at that RPM? If the latter is true, wouldn't an engine achieving 30K-35K RPM and 210g/cm torque be better suited than one that does 210g/cm torque at 40K RPM?

Ohi! It's me; that flywheel obsessed guy from MTB!

The trade off between RPM and torque is the stored energy and the stored energy recovery rate. The difference between Shark 40Ks and the MTB Rhino motors we are about to start distributing is practically minimal. The MTB Falcons are designed to handle 15 darts per second which is way more than any pusher motor can possible fire out of a Rapidstrike. The higher RPM of Sharks could allow for a sustained ROF of 18 darts per second but even the old ultra high RPM Ranson motors in the pusher only get about 12.

Using the maths and simulation i developed for that paper you get the following results:

A Shark will spool up to its stable 18 DPS RPM in 0.21 seconds
A MTB Rhino will spool up its stable 15 DPS RPM in about 0.22 seconds

The soonest you can fire a 120fps dart out of a Shark is 0.19 seconds
The soonest you can fire a 120fps dart out of a MTB Rhino is 0.2 seconds

tl;dr Sharks are "better" but the performance gain is absolutely minimal; particularly for motors that will cost about 4-5x as much.

[jwasko]

I've heard of durability issues with Sharks. The Falcons (aka the upcoming Rhinos) don't seem to have that issue.

As to heat, I've seen Duke Wintermaul put computer cooling fans on the side of blasters but I thought that was more to cool the motors. Never heard of melting plastic from motors.

Edited by jwasko, 17 July 2015 - 10:50 PM.