Is there any legal way to fly an inline twin-engine aircraft with only a single-engine endorsement? For example, if it's an ultralight or amateur built?

I understand Rutan's Defiant was an inline twin that could take off, fly and land with either the front engine, rear engine, or both.

I assume you can do this in a twin inline ultralight as there is no twin engine ultralight endorsement in USA or Canada.

I'm asking about the ultralight or amateur built categories in the USA or Canada, not the US LSA category as I understand they are single engine only.

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    $\begingroup$ You should specify what aviation jurisdiction you're in, because rules for ultralight or microlight aircraft vary between USA, EU, and various other places. $\endgroup$ – Zeiss Ikon Aug 28 '19 at 16:18
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    $\begingroup$ Long before Defiant, the Cessna Skymaster was demonstrated with either engine running (and the second at idle, for safety) on takeoff and routine flight. Before that, a P-38 could do it, and it wasn't even an inline design. $\endgroup$ – Zeiss Ikon Aug 28 '19 at 16:20
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    $\begingroup$ I just noticed, you have two distinct questions here -- one concerning Defiant (and applicable to other inline GA aircraft like the Skymaster) and the other relative to microlight/ultralight. You should ask only one question here, then ask the other separately. $\endgroup$ – Zeiss Ikon Aug 29 '19 at 14:19
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    $\begingroup$ the question is what categories is this legal, if any $\endgroup$ – Fred Aug 29 '19 at 14:46
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    $\begingroup$ Okay, I see tags for FAA and Transport Canada -- which have significantly different ultralight regs. Which is it? And you only want the ultralight/microlight question answered? $\endgroup$ – Zeiss Ikon Aug 29 '19 at 14:50

Under United States Part 103 ultralight category, with no license or aircraft certification requirements as long as the the limitations of the category are met (dry weight, fuel capacity, single seat, and level flight maximum speed, permitted flight locations), you can do anything you like. Whether it's safe or a good idea is up to the pilot.

Last time I checked, Part 103 requires a dry weight (with engine, no fuel, no pilot) under 254 lb, no more than 5 US gallons (though actually called out in liters) fuel capacity, and level flight speed limit of 55 kt (about 62 mph).

I can't answer relative to Canada, as their regulations concerning ultralight/microlight aircraft differ from those in the USA.

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    $\begingroup$ What is the fuel capacity.... when the fuel is electricity? :) $\endgroup$ – Fred Aug 29 '19 at 16:34
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    $\begingroup$ USA Part 103 specifies a maximum capacity because electric flight wasn't a reality when the regulation was written. I presume they'll get around to electric endurance limits eventually, but in the meantime, your capacity is less than ten gallons of gasoline. $\endgroup$ – Zeiss Ikon Aug 29 '19 at 16:36
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    $\begingroup$ So is there no electric endurance limit? I thought the maximum fuel capacity was 5 gallons. Has this increased? I also understand the maximum weight is 250lbs, not including safety equipment. Is a small sustainer engine safety equipment? In an emergency I'd rather have a controlled flight onto a road or clearing, or the next airport, than using a ballistic parachute to fly uncontrolled into terrain. No better safety equipment than an extra inline engine ..... $\endgroup$ – Fred Aug 29 '19 at 16:41
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    $\begingroup$ Yep, you're right on the fuel capacity. I haven't looked at Part 103 in detail since I determined I'd never be able to afford a ultralight combined with storing/living anywhere I could fly it (no flight over populated areas like towns). These things do glide, after all -- you won't just fall if the engine quits. Same situation as a Cessna 150. The parachute is for structural failure or unrecoverable attitude. $\endgroup$ – Zeiss Ikon Aug 29 '19 at 16:46
  • $\begingroup$ Glide like a brick, more like it. lol. like 10:1 ratio. So if you're at 2,000 ft and your dropping at 500ft/min, you've got 4 minutes to find a spot, fly to your field of choice ( basically the one beneath you) and do a final approach (with no go around).... $\endgroup$ – Fred Aug 29 '19 at 18:21

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