Monday, June 19, 2017

Combat Tested: Hooligan Flywheels

(Disclaimer: I was sent free samples.)

This is Hooligan Blaster Company's first flywheel product.

This is a CNC machined, Delrin, smooth, mild-concave (Artifactoid profile) superstock-standard flywheel in the 35mmOD class.

It is essentially a product-improved and higher quality replacement for the old Artifact V1 truncated smooth flywheel and is a nice universal option that supports a variety of cages.

Comparison to the Artifact V1 truncated (right):

Dimensions: 33.83mm root diameter, 34.88mm OD, 14.3mm rim width, 29.92mm ID

Machining quality is excellent and noise/vibration/harshness levels are approximately where the bar is currently for a machined SSS wheel. Some, such as DRS Performance (proprietary geometry non-SSS) and Containmentcrew may have this wheel beat for dynamic balance, but not by much.

Shaft fits are quite tight. This is a high-reliability feature and is desirable in this type of press-fit flywheel if you want it to stay on the shaft under modern motor torque curves and crush ratios. I did not find installation to be difficult. To recap a bit of proper tech practice, support the outboard motor shaft end (or on FK motors, the end surface of the bearing housing as per Mabuchi instructions, if the bearing housing is closed on your particular motor model) when press-fitting driven attachments to motor shafts.

I have been running these wheels on 20mm brushless inrunners:

...for a good while now, and fired several thousand rounds on this cage without any issue with walking or shaft fit durability. Other flywheel products such as Artifact nylons are not up to this task.

Chrono session on the same cage (stock 43.5mm AR, GWS 4600kv on 2S) using Gen3 koosh and Raytheon waffle tip

Some of you may not understand, but my huge motors are not an extraneous variable. Rather there is a case for them being good science - because as long as you are 100% sure about never getting forced to subcritical regime, motors don't matter a damn bit. There are motors that have sufficient torque and get the same velocity as all others that have sufficient torque, and there are motors that don't have sufficient torque, and are an extraneous variable because they don't have sufficient torque. This holds at least for similar speeds (so thermal effects of the slip speed on friction behavior aren't an issue), and my 4600kv lands these right in the same realm as any normal FK130/180 at 34,040rpm.

My sole nitpicks on this wheel are as follows:

One, the adherence to the 35mmOD class (same as Worker, Bighammer and Artifact truncated). This is fine for universality and retrofitting oddball Hasbro and older generation cages that lack clearance for 36mmOD class SSS concaves, but these days, most/many cages have 36mmOD clearance designed in. The tad less envelopment is one possible reason why these are a bit under the weather versus the Artifact fullprofiles.

Two, the material and/or surface finish result in poor development of transfer layer. The engineering plastics that a polymer flywheel is made of are themselves universally not good for friction against anything. The traction merits of a polymer flywheel come about because they develop a transfer layer, or buildup layer, from high-temperature dynamic friction contact with darts (which are composed of polyethylene and thermoplastic elastomers). This is much like the transfer from automotive brake and clutch frictions onto their steel mating surface. That transfer modifies the resulting friction behavior. In smooth flywheels a large empirically known factor is that rougher surface finishes do not build up as well and perform worse than a mirror polished surface. The Hooligan FAW's surface finish is good, but still has a lot of concentric tool marks and is matte. The true Delrin is something that has been thrown around as well; there is suspicion that acetal copolymer (i.e. Quadrant EPP Acetron described here and many others) is a superior flywheel material than Delrin (acetal homopolymer).

Three, it is heavy at 7.0g-ish and has a lot of inertia. The rim wall thickness is slightly greater than Artifact V1 truncated, which has a 30.14mm ID at very similar root diameter, OD and groove radius:

It dulls startups if the motors are not up to the task. Fitted to old Tacmod on 3240s:

These are not recommended on 130 motors for sure. Not that I recommend 130 motors anyway - but for sidearm builds, lighter flywheels are of benefit. At the same time, I would rather have a reliable and structurally sound wheel, and there are no other Western-made good quality machined wheels for generic SSS cage application but the similarly-heavy CC Cyclone, and the crush/velocity-reducing BlasterParts. Overall, it is a minor issue.

Now this one could go either way: The profile is straight-up old school Artifact and is a mild-concave. If the radius were decreased, it could theoretically result in greater and more uniform grip as per my last post. However, given the low degree of envelopment that is possible in classical SSS formats and ~34mm root diameter (especially with 35mm OD flywheels), this may be a necessary aspect of design to prevent the groove from being a tiny width and leading to problems with rim-pinch. Similarly the competing CC Cyclone flywheel runs a very large groove radius to similar results (a few fps higher in correlation with visibly better transfer behavior, copoly acetal, and smoother finish). It may be that hydrostatic contact is worth approximately nothing at this near-cylindrical level.

In the end, do I recommend this product? Absolutely. For what it is and what niche it seeks to fill, it is an excellent product. I cannot overstate the significance of having a default basic flywheel to buy that doesn't suck. Prior to this offering and its competitor from CC, there were no wheels that entirely fit that description. There were only serrated 32.8mm Workers, low crush BlasterParts, roughly machined and constantly-sold-out Artifact nylons, and some aluminum also-rans that just can't get a grip.

Finally, I'll link this Tampa Bay Nerf Club video again in which I am running these wheels, on the brushless AR cage shown above:

Solid as a rock.

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