I just got educated by private message on how Wren's work and have heard this argument over "autostart" before related to AMT engines which have "Autostart" even though they are airstart. So I believe the PM is important enough to share:


Hello Sean,

Just a note about your post re Autostart/Airstart.

Some people on RCU seem to think that if an engine isn't Autostart it must be air start. Not true! Wren are alone amongst the major manufacturers in offering an alternative to full Autostart, known as the ECO ECU.
With full Autostart, there are valves which operate the gas and fuel on start-up, and the glow plug and starter are operated automatically. With an ECO, you operate the gas, glow and starter. The starter can be either a wand or an onboard starter. Once the engine is running on gas, the ECU senses the heat via the thermocouple and starts the pump to set the fuel flowing. From there onwards the ECU takes over, you unplug your gas, glow plug and starter and go fly.

There are two main reasons for our use of the ECO rather than full Autostart. Most important is that our small engines are used to power smaller jets, where weight is a big consideration, and you can save over a pound in weight by not having valves, onboard gas, onboard starter battery etc. There are also fewer items to install in the fuselage. Over 80% of Wren jet fliers use the ECO for this reason.
The second reason is the cost - we aim to provide the lowest-cost jet flying, where people can not only build their own engines but also save money on maintenance because many fliers need to keep the cost as low as possible.

Regards
Sara Parish
Wren Turbines Ltd

For what it's worth, I personally refer to Autostart being a function of I flip a switch and everything automatically starts like how a Jetcat, or Ram with Autostart or most the new simjets work. I understand there are multiple uses of this word across turbine manufactureres so best to check with each one to figure out what you are getting.

In my opinion, the "full autostart" as in how a jetcat starts is the best option, but there are many many many (most AMT users come to mind) that like having full control over their starts ) and to those guys, I say, get a knee pad