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24 volt?

Posted: Sat Apr 01, 2023 1:25 am
by daverumph
I put in a deposit on a HW last fall, so it will be a while before I can actually start building, but I'm thinking/dreaming about the myriad choices to be made.
Here's one I haven't seen discussed: I've seen that the Rotax 915is and newly announced 916iS are available with either a 12v or 24v electrical system (starter motor, and generators). I've never seen anyone discuss building at 24v Sling, but I wonder why not. The Cessna 172 I learned to fly on has a 24v electrical system. It looks like the 24v version's generators produce 800w, compared to 400w for the 12v system (which is the same current at double the voltage). If I understand that correctly, I think it would be pretty valuable.
For sure the battery would need to be 24v rather than 12v. What would be the implications on things like trim and flap motors, lighting, avionics, etc.? I still have a lot to learn about how it all works!

Re: 24 volt?

Posted: Sat Apr 01, 2023 9:34 am
by BG8473
Good question. It's one of the questions I have as I contemplate a future build. There may be more 12 volt gadgets available for homebuilt (especially those who use the automotive components). The 12 volt batteries and chargers are likely cheaper. A couple of benefits of 24 volt systems include lower gauge wires due to less current, and some air conditioning systems (which I may consider) are only available in 24 volts.

Different topic, but I see you ordered a High Wing. That's what I am eying. Did they provide lead time? Are they delivering the full kit at one time, or piece by piece (empennage first, followed by wing, etc.)?

Re: 24 volt?

Posted: Sat Apr 01, 2023 1:32 pm
by daverumph
When I put in my deposit last fall, they were only giving a rough estimate of "2 and a half-3 years", and that there were at that time 200+ potential customers ahead of me. (Since the deposits for reserving a place in line are fully refundable or convertible into a TSi, they don't know how many HWs the list actually represents.)

My understanding is that the kits will be available piecemeal or all at once, like the other kits. There is a discount for buying them all at once. The listed kits are Empenage, Wings, Fuselage, Undercarriage and Canopy/Dash/Final Assembly/Finishing, same as for the TSi. It's best to get in touch with Barry Jay at TAF for current info.

Re: 24 volt?

Posted: Sat Apr 01, 2023 10:31 pm
by daverumph
I see that someone asked the equivalent to my 24 volt question in the Firewall Forward section of this forum. TAF replied that they are not currently planning to support the 915iS C24 engine because of some 12 volt components used, including flap and trip actuator motors and lighting. They may support 24 volt at some point in the future, but it sounds like not soon.