If you are going with a dual wheel shooter, you might want a bit more reduction. A hooded flywheel shooter acts like it’s own 2:1 reduction, since the ball rolls along the edge of the hood. If you are doing a dual wheel, I’d consider something more like 3:1 or 4:1.
I think the point is that there isn’t enough power there to launch at that speed with any regularity. 118 mph is 52.75m/s. As the PC weighs ~5oz (AndyMark product page), it masses about 0.14kg. At that speed, the PC has a translational kinetic energy of 194J, and probably another 100J in rotational kinetic energy. Operating at its advertised peak power (a great way to kill a motor fast!) of 279W, it would take over 1 second to recover the flywheel between shots.
Added a half hour later: Also, the NEO 550 is ~45% efficient at max power, so you’ll also be pushing your 40A breaker, even if you had a magic CVT that let you run at that condition throughout spinup. In reality, you’ll start out far to the left of peak power speed and either trip a breaker or smoke a motor. Looking back at the OP, it appears to be the latter.
We are going with a dual wheel shooter with timing belts.
Yeah, NEO 550s aren’t exactly the best choice for shooter motors, especially without reductions. For comparison, our shooter uses 4" wheels and is powered by a pair of Falcon 500s on a 1:2.5 (geared UP, rather than down). NEO 550s have roughly a third the power of a Falcon 500, and have a far smaller thermal mass, and thus will burn out much easier.
Now granted, if you’re not trying to shoot halfway across the field or anything crazy, then you could probably gear NEO 550s down far enough to use them for a shooter, but it definitely wouldn’t be my first choice.
We tried NEO 550’s on our shooter direct as well and they also smoked, which was due to us using mounting screws that were too long. When we took them out they looked burnt and when we replaced them with shorter ones the smoke went away.
I would disagree we have a 6" HiGrip Wheeled Set up with 9.5" between axles with a 3:1 reduction on each neo 550, and we have seen amazing results (accurate shots from distances greater than 30’ away).
We tried a 1:1 on a NEO550 with a 4” wheel, as was able to shoot pretty far back. It’s definitely doable. Not saying it’s a good idea…
At what cycle time for the second ball?
There’s nothing magical here it’s all just gear reduction, power and torque. You can make the shots with a 550 - assuming you’re willing to accept a reduction in time to subsequent shots to let it speed back up. So while a twin Falcon shooter might be unloading 5 balls over the course of a couple seconds, the 550’s will take much longer to cycle back to a shooter speed (it’s a simple ratio of power amounts).
Of course, you can add a flywheel to mitigate the power drop after each shot, but then the 550’s will take additional time to get to an acceptable speed initially- again based on the motor power / torque / gear reduction.
If you accept that the majority of competitive teams are going to be using falcons or NEOs to power their shooters, then it’s a reasonable argument to make that the 550’s are going to be subpar in comparison.
Do the math and argue the numbers. If 40 to 60% longer ball-shooting or spinup times are acceptable, then a couple 550’s might fit the bill rather than using a couple falcons.
That’s a pretty cool speed. Probably could get you to outer space.
I would like to mention we are not going a hooded shooter and rpm dropped about 200-300 after shot and would get back to speed quickly. The casing of the neo 550 acts as a fly wheel since it spins as well, but I think you are missing the compression aspect. These power cells can squeeze down to 1 inch and with the right grip on ball, greater energy can be transferred. Yes I understand that a falcon or neo would be faster and have more torque but with the wrong compression it will not matter as you are not transferring as much energy to the ball.
The mass of the outrunner casing on the 550 is nowhere close to providing enough rotating mass to serve as en energy storage flywheel. If you are getting the results you desire that’s great, but it’s not because of the casing.
Something to consider is the brushless motor itself. Brushed motors have more rotating mass internally, this acts as a flywheel to help preserve inertia when the ball is shot. We are using a direct drive CIM on each 6" AM Hi-Grip wheel and have no problems shooting as far as we need to, we actually posted a video to our YouTube channel here: https://www.youtube.com/watch?v=8Fdwi57x8js
So the question is why do you need to use a brushless motor in the first place?
Efficiency, Power, and consistency with all of our other motors are the main reasons.
Integrated encoder, increased efficiency, smaller package, all coming out to a lower price (encoder considered) is fairly compelling.
Having taken apart a CIM and looking at that rotor… I have a hard time imagining the rotor within them is a serious inertia contribution.
The rotor weighs a pound (at most) with a radius of 0.75"… 1lb x (0.75in)^2 = .56 lbm in^2.
A smoothgrip wheel is 0.6 lb with a radius of 3"… 0.6 x (3in)^2 = 5.4 lbm in^2.
There’s an order of magnitude there.
Gear ratio also plays a part - to the square of the gearing. If the CIM is geared down by a factor of about 3:1, they’re roughly equal. If it’s geared up, there’s an even greater difference.
Added: In inertia, it’s only linear, it’s to the square in energy stored.
The rotational kinetic energy that gives the “flywheel effect” is proportional to the mass and the radius of the location of the mass squared. Thus, a mass near the shaft has much less rotational kinetic energy than an equivalent mass further out. Most commonly, flywheels have the mass concentrated at the rim, as far as possible from the shaft to maximize the rotational kinetic energy.