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Further Rapidstrike Developments

After getting the chance to use my Rapidstrike at the last Saturday Skermish, I was able to identify some problems with it. First of all, the main issue that I encountered at the end of the day was the flywheel popping off during full auto. I was using the RS to empty some spare mags when this happened. I put this down to inconsistent darts or different varieties. When serviced, nothing seemed out of place other than the flywheel, nothing was noticeably to fault. The second problem that I noticed was the rate of fire. Upon completing the build I was quick to notice the rather slow ROF, this became an issue when I was in a game and needed a player tagged. Both triggers were held with a full mag, but all darts failed to hit the target. Yes I'm aware my aim is a little off (a lot) but the circumstances would have benefited from a higher ROF.

This leads me onto the improvements that I have made to this RS. Firstly, I PLAN to acquire some Worker Wheels to swap for the stock ones. This should hopefully result in cleaner sound from the blaster along with more consistent shots. The second issue was resolved using an XP 180 and a couple of diodes. I quarrelled with the idea of a purely 3S XP, but then saw sense and dropped the voltage a tad. I used two Diodes in series in the power line from the rev switch to the trigger switch. These diodes hide next to the MOSFET in the base of the grip. They are covered with a long sleeve of hearshrink.

I am pleased with the pusher upgrade as I am now getting the ROF that my arsenal was lacking. I believe that this setup could be brought down even more for a more user friendly experience. I chose to put the diodes where I did as the splice near the motors feeds the power to my voltmeter and LED. The ROF is very satisfying and has the reliability of the XP. Single shot is of course still very possible with a steady finger.

Comments and Criticisms are always very welcome.


Small Clip -

XP180's over rev on 3s and their short shafts which are slightly smaller than other motors pound out the flywheel centres. You should also take the worm gear in the pusher and reverse it on the shaft. Mine destroyed one end of the wormgear even on 2s.
Run that on 2s if you want any kind of reliability or put Hellcats in, they have much longer shafts that retain the wheels much better. Worker wheels on 3s hellcats is better than the same in XP's as you are not doing 50k rpm.

The Flywheels are already Hellcats, it was originally a triple Hellcat build but I used the XP instead on the pusher.

Well I haven't seen Hellcats pound out a flywheel yet. If you fit and remove them hot (hairdryer) they should stay on. Workers will fit that set up much better though.
I would put a third hellcat back on the pusher, they are much better. Overkill RoF gains nothing, reliability is much more important. the pusher wiorm gear is already vulnerable to damage, running short, slippery shaft XP's on it won't help.

OldNoob wrote:
Overkill RoF gains nothing, reliability is much more important.

Speaking as someone who maxes out at 7dps, you really don't need more than SA. I'm trialling FA suppression for situational moments like room clearance and the like but if you really need a player gone, close and keep firing.

That said, I wonder if you have a technical problem deep somewhere in the build. I've never had an ROF problem at FA on Rhinos let alone Hellcats. How long was it taking you to dump an 18 magazine?

That's why I think the worm gear is spinning on the motor shaft.

Are you referring to the Flywheel incident or the ROF concern? The pusher was working fine, equal to similar builds.

Another development that I was considering was switchable diodes. A MOSFET would be useful in this application as I could hide a small slide switch at the back of the jam door.

How would you use the Mosfet to switch in the Diodes?

That's what I need help with, ideally just so I can use a smaller switch.

I think you need a double throw switching device whereas a Mosfet will is effectively only single throw. You could use a double throw relay but I think you should be able to use a nice micro switch to do the job and cut out the middle man for the one motor.

I mean.. Maybe you could use a small double throw on the gates of two P-channel or N-channels.. But that sounds like something I'd consider so is very likely daft. And you'd have to protect each circuit from back EMF so your blaster would be lousy with diodes.

Edit: sorry I implied that you'd need more than one fly back diode but you wouldn't. Just been staring at a RS circuit.

If you're only switching in/out one set of diodes (i.e. you just want a "high" and "low" RoF setting) you can just use a single FET to bypass the diode(s) you want to switch out. You'd have to use a P-FET if you wanted to put the diodes on the +ve side of the motor but there's no issue with putting them on the -ve side if you really want to use an N-FET as long as they are located outside of the braking loop.

EDIT: You could do the same with a simple SPST switch with a high enough rating - you don't need to select between banks of diodes you just need to bypass the ones you aren't using at the time.

I am not a fan of throttling ROF, but in this instance a FET is overkill. A decent 10A two or three position switch with no fet required will easily handle the current in the pusher circuit. See the switch in my Krinkov.

I has not thought that through.. So you could use a 'single throw switching device' and just short circuit the diodes.. Interesting. I could use that.

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