Wyvern Quick Start Video

The Wyvern ships in the same packaging as the Backdraft Phoenix. The seal on the box has some info about the engine and a QR code that links to this guide's video.

Inside you'll find:

Wyvern HPA engine

Fire control unit (FCU)

Trigger board

Inner grip line

Wire harness (internal, external, or both, depending on what you ordered)

Exclusive beta tester stickers

Heads up: the engine and grip line look different from the product photos. All good changes, in my opinion.

You might be wondering about the two holes on the side of the engine. Each hole has different spacing, which lets you shift the engine forward or backward in the gearbox. That means one nozzle works for both AKs and M4s.

12-pin connector → your FCU

Three wires → your trigger board

Solenoid output with the red wire → the front of your engine

Solenoid output with the white wire → your solenoid

Green and black wire → accessories (not used in this guide)

Battery connector → your battery (see below)

This version of the Wyvern needs a 3S LiPo. The nozzle pulls back with an electromagnet and extends with a spring, and on this prototype the electromagnet isn't quite strong enough to compress that spring on 2S.

Don't worry: the next version will have a stronger magnetic coil and run on a 2S LiPo like most other engines. For now, 3S LiPos are pretty cheap, and our fire control unit is more than robust enough to handle the voltage.

Another brand's fire control unit (which probably has fewer features than ours) might try to extend the nozzle instead of retracting it. Since the spring is already holding the nozzle forward, it'll look like your engine isn't doing anything.

That's what the small polarity adapter is for. It goes between your FCU and the engine and flips the polarity, so the FCU sends current in the right direction and retracts the nozzle when you fire.

The wire harnesses that come with the Wyvern already have the correct polarity, so if you're using our FCU, you shouldn't need the adapter.

1. Open the app and scan for devices, then pair with your wireless FCU.

2. If you haven't paired before, use the default PIN: 123456.

3. If the app offers a firmware update, run it. It only takes about a minute.

4. After updating, power cycle the FCU (unplug it and plug it back in), then scan and pair again.

5. If the app says your settings are mismatched, you can read the settings from the FCU, or switch to a saved profile and write it to the FCU.

The app lets you save multiple profiles, so you can keep separate settings for each of your guns.

From the side menu you can disconnect, rename your FCU, change your FCU PIN, or update firmware. You also get five classes you can rename however you want.

Manual upload: sends your settings to the FCU when you tap it.

Autosync: uploads settings as you change them, so you don't have to open the menu and tap upload every time.

Sync rate of fire: turn this off to set a different rate of fire for each mode. For example, a slow 3-round burst and a fast full auto.

Trigger: select the trigger board you're using (for example, M4).

Engine type: choose dual solenoid, since the Wyvern has two solenoids.

Fire modes: pick the modes you want. There are plenty to choose from, with more on the way.

There are four settings:

Poppet dwell: how long air is released. Lower is more air-efficient, but keep it high enough that your shots stay consistent. Start high and turn it down until you notice inconsistency.

Poppet delay: the time between releasing air and retracting the nozzle. This is usually low, because the BB has probably left the barrel by the time the air stops.

Nozzle dwell: how long the main solenoid turns on to fully retract the nozzle. Start around 15 ms and go as low as you can without feeding problems. Too low, and the nozzle won't pull back far enough to load a BB.

Nozzle delay: the time between retracting the nozzle and firing the next shot. Turn this up if you want a lower rate of fire.

Rule of thumb: set your dwells as low as they'll reliably go, then turn up your delays until you get the rate of fire you want.

Example: 7 ms poppet dwell, 2 ms poppet delay, 13 ms nozzle dwell, and 8 ms nozzle delay works out to about 33 rounds per second. You can push it faster, though the Wyvern won't quite match the Phoenix's top rate of fire. Once you're set, upload your settings and watch the nozzle do its thing.

Stuck on your build? Text us at +1 (920) 522-2157 or ask in the Discord. Real humans, fast answers.

Don't have a Wyvern yet? Beta kits are still available (for now), but there aren't many left: Get the Wyvern Beta Kit →

Thanks again for your support. I couldn't do this without you guys.