From my online research and limited experience [...] it seems like everyone wants higher FPS darts coming out of their ...blasters. Based on my limited testing and observations, if the dart moves too fast, the darts are inaccurate and have no precision (imagine using old school Nerf streamline darts in a singled Titan). Using the same setup, slower moving darts have higher accuracy and better precision, although generally get less range. Therefore, I have concluded that there is a "sweet spot" between FPS/range and accuracy/precision when using standard Nerf Elite darts of Koosh darts (Gen 3). However, I've never see anyone reference this idea. QED: I'm missing something here.
Does anyone know what I'm missing or can shed some light on my ignorance?
You aren't missing much in terms of stability and velocity for the majority of superstock darts, especially the older and less favored types like Streamline and Elite. All I would consider you to be overlooking, and this does get partially into personal preference and situational factors, is that maximizing precision (minimizing spread) is definitely not equivalent to maximizing combat effectiveness
of the superstock blaster system. Targets don't sit still in the open 30 feet away. Trajectory flatness, maximum and effective range, retained velocity, and time on target are considerations that favor the use of the highest legal/safe velocity available. Coming up with an effective solution means balancing those with accuracy issues, similarly to the selection of ammunition to balance aerodynamic efficiency and velocity retention with stability.
Nowadays with the much improved darts in .50 cal (such as koosh, ZS Elite, USD, USC, FVJ, FVN/Hardball, ACC, Kforce, and even standard Hasbro Elite to a large extent) which are much more suited to the 100-130fps band, if you ask me, the accuracy problems are dead and gone, and the best bet is to milk those safety limits for every last joule you can put on darts. Velocity gets hits. What would you rather have, a 70fps stock rampage, or a 120fps RS build? Who can take a quick aimed shot across a 45 foot clearing and hit the enemy as they pass a doorway without tons of unintuitive elevation and lead? If both of these players engage each other simultaneously, who is advantaged? Who can reach a horde at 30 yards for area effect? Who is least likely to have a dispute with a zombie? (But who is best at plinking cans off the fence in the backyard?)
This opens a whole other can of worms due to the physics of these beasts. There is a proper document by rhino_aus (the Rhino motor guy) describing what I cover below out there but I forget where.
Those Stryfes and such (i.e. "Nerf-design flywheel systems") you see shooting 100-130fps are operating in dynamic friction. The flywheels turn at a surface speed significantly in excess of the maximum velocity a dart can obtain during its contact with them ("critical velocity" which is first reached at "critical speed", approximately 25,000 rpm for the 1.25" 10mm gap system and a typical dart). This mode of operation i.e. "supercritical" is key to flywheel launchers, in my opinion, being viable
in the nerf hobby as anything more than a niche or high-priced product.
The reason behind that is simple: As long as flywheels maintain at least critical speed, velocity and flywheel speed have no relation. Since the dart is always skidding on the flywheel surface, the difference of speed between the two is largely insignificant to the force applied on the dart, and so as you shoot and the motors (which are PMDC with linear torque curves) operate under variable loads and hence vary in speed, the velocity of darts doesn't change in response. Supercritical flywheel guns have a definite capability to support ROF, corresponding to the maximum load under which the motors can maintain critical speed; for instance one can calculate 15rps for the Rhino/3S lipo system and 35rps for the FK180SH-3240/2S lipo system both with Nerf geometry and standard ~1.2g darts. Exceed that, which for these setups is not easy, and velocity starts drooping.
Supercriticality also moves the critical speed far enough down in the torque curve that the torque at that speed is high and the total time to accelerate from rest to that speed is only a small fraction of the time to reach full speed - hence quick response. You need not rev one to full speed to get a 100+ fps shot off.
By contrast, i.e. a stock Nerf flywheel gun operates in static friction mode i.e. rolling contact and hence has a supportable ROF of zero
rps and a theoretical full-velocity response time of either infinity or 5 time constants (depending on who you ask) - in other words. equating flywheel speed directly to dart velocity is not good. Well, enough theory. Grab a stock Stryfe and rip on it, watch the darts fall shorter and shorter. That is subcritical operation and it is bad. M'kay?
And what that means? You CAN'T, properly speaking, "turn down" a flywheel blaster's velocity without a major tradeoff to other aspects of performance. And that is part of why they all shoot full velocity - because they can do it consistently, and consistency is practical accuracy.
As a small update, I modified a Stryfe with MTB Rhinos. I tested them with a 6 cell and 8 cell NiMH AA eneloop pack. The 8 cell pack shot the darts noticeably faster, but the darts were MUCH more inaccurate. You could compared the performance of my darts (Gen 4 Koosh) to stock nerf Elites...ok, not that bad, but comparable.
The 6 cell pack shot the darts well, although not as well as fast as the 8 cell pack. However, the darts were MUCH more consistent. My current Stryfe setup uses a 6 cell NiMH pack instead of the 8 cell pack.
The 6 cell is subcritical. The 8 is super. That is the major difference. The 6 should get about 90 fps. The 8, 100-120.
Fortunately, Rhinos and a 6 cell nimh pack will give plenty of torque and since it's a semi-auto and probably doesn't see major ROF you should be able to get away with that. The question is whether it really serves your needs. Can you make it start drooping by shooting as fast as in a game? Can you get a ~80% velocity response shot off from standstill?
I still think you should take the 8 cell into combat, as the 120fps is where it's at. Again, it IS personal preference and situational. Some people (see: BURN and their AR equipped rampages) prefer about 90 fps for better accuracy. I find it lacking reach and hitting power.
Also, does anyone know if the Stryfe and Rapidstrike use the same flywheel motors?
They both accept 20.4mm flat can motors.
They both come stock with FA130 motors.
The stock FA130 motors are not the same motor. The Stryfe motor is the common Nerf semi-auto motor (Demolisher, Rapidred, Cam, Stryfe, E-Ray, blah blah blah). You usually run it on a 3S lipo for superstock. The RS motor is a lower turn (hotter) wind. You usually use 2S for similar speed to the former, and it does make more torque, 3S blows them up, and they don't last but a year with stock metal brushes.