Brainstorming next coil sync, Async RSGTC, duel mot, or NSTs.

[DownwithUmbrella]

Hello friends! it's nice to see the hV community expand in new directions.

I'd like to start this thread in the planning Phase for my next tesla coil.
so far under my belt I have built a SGTC, half & full bridge SSTC, and a  VTTC. I'm ready to step up the game.
Leftover from my various projects I have a large amount of capacitors, mots, NSTs, mosfets, and magnet wire. Time to build something with larger streamers.

I'd like to jump the power up of the coil and graduate to a rotary spark gap but haven't decide to use phased NSTs or build a multi mot bank. Has anyone tried using a high RPM brushless DC drone motor for an asynchronous gap?
Lately I've been inspired by Steve Lane's phase controlled synchronous rotery gap.
Can anyone who has built a Dual MOT TC suggest some of the pros and cons?

[Mads Barnkob]

I do unfortunately not have much to add as I never built anything but a very small SGTC.

But there is a large difference between dual MOTs and a NST, two MOTs in series would only be around 4000~VAC and depending on which NST you have it is 9000~15000 VAC.

The lower voltage, the higher current, so a rotating spark gap would get worn down much faster and the sparks would also be more difficult to quench with MOTs

Since you are thinking about "unlimited" RSG speeds, have you looked into DC resonant charging coils? That is without a doubt what I would build if when I will build a SGTC one day in the future

[Hydron]

"propeller" gaps, with just a spinning rod (maybe with tungsten tips) was a popular idea a while back, and could potentially work with a BLDC motor. Well before I actually built my first coil (a DRSSTC) I had planned to build a DC resonant spark gap coil with MOTs (probably 2x with primary phasing chosen so that both cores were grounded) and one of these gaps - bits are cheap and readily available.

Richie Burnett's site is very useful and informative about DC resonant coils, among other subjects: http://www.richieburnett.co.uk/dcreschg.html#resonant

[oneKone]

The only advice I can offer is about the bldc motor. Hobbyking and banggoood are two very good cheap sites you can get an outrunner, ESC, prop adaptors and a servo tester from. Another thing to keep in mind is that a 1100kv motor will do 1100rpm per volt.

[DownwithUmbrella]

Excellent responses. Apologies for my rather ambiguous topic but I'm moving in this directing:
I have 4 Large NST, I'm Leery to use them due to their physical size factor. I have decided to go with 2 large mots with their secondaries in series ground at the mid point. Fortunately there's a bit of information regarding this set up on the web. I.e loneocean built one as well as others.  Mot Capacitors and 3A diodes will essentially double my voltage to aproximently 9kV.
I have moved away from an asynchronous design and acquired one 3600rpm synchronous teletype 1/20hp motor.

 Mads Barncob, it's quite possible the high amperage will be a considering factor in my spark gap design. To midigate this I have sourced off Amazon copper tungsten alloy electrodes. $$$:(
I'm hoping this will be able to carry the current. My next concern is the larger heavier electrodes will lag the low horsepower motor. Due to this I might down size to 1/4in tungsten/Cu electrodes.

Also still to order are the Caps for the MMC. The quantity will be determined by my choice of Power supply.
Bonus fun, I'm designing a power control box with a keyhole switch, relays, breakers, line filters, amp/volt meters for power in/out. Could anyone provide me with links of some you've built in the past just for inspiration?  I'm sure you all have heh.
I'm in no rush but as I make progress I'll post some photos.
Thanks

[Mads Barnkob]

I only have a 3x13A variac that I put a safety stop on, start/stop with hold and drop on voltage loss/emergency stop.

I also added a 6 channel data monitor that draws graphs of 3 phased voltages/currents.

http://kaizerpowerelectronics.dk/power-supplies/3-phase-13a-variac/

[MRMILSTAR]

In the world of spark gap coils, long streamers require a big power transformer. I don't know your budget but have you considered a pole transformer? Yes, they are big and heavy but they are practically indestructible and can give you more voltage and current than you will ever use. I use a 10 KVA unit that puts out 14.4 KV. It weighs about 300 pounds but is on a nice cart for easy moving. If you look, you can find them on E-Bay for around $500 or less. Delivery can be expensive unless you can pick it up yourself, which I did. I get 9-foot streamers with 6.5 KVA from my 8.6" coil with this transformer. You can also make a pretty amazing Jacob's Ladder with it. When people see it connected to my tesla coil, nothing says "big power" like the look of a pole transformer.