The CalAir A-9b, for instance...

On 10/16/2020 8:50 PM, 2G wrote:
On Friday, October 16, 2020 at 4:53:50 PM UTC-7, John Foster wrote:
On Friday, October 16, 2020 at 8:11:13 AM UTC-6, waremark wrote:
Take-off performance looks impressive. I was surprised by the amount of noise - sounded not unlike a petrol engined aircraft as it passed the camera, although presumably it is actually much less loud.

Any idea what the endurance is of that aircraft?

As the owner of a petrol self-launcher, I like to know that I have enough endurance for a launch to 2,100 feet (700 m), a relight if necessary, and a reasonable self-retrieve later if necessary. I will stick to petrol until batteries can cope with at least that.
Much of the noise you hear from any propeller-driven aircraft comes from the tips of the propeller breaking the sound barrier. That won't change between an electric vs petrol engine. The longer the propeller, the faster the tips move.
My ASH31Mi has a 1.55m diameter propeller that has a max rpm of 2500. If you do the math, this works out to 454 mph, well below the speed of sound. Few GA aircraft have props that go supersonic, and you can really tell those few that can.

Tom

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Dan, 5J