==============================As you know if you have a total of 50hp with two engines it is unlikely to maintain altitude on a single engine (with any appreciable weight) because of losses due to drag will make the effective power available closer to 37% than 50% so on single engine you will have effectively more like 18hp than 25hp. Also you likely don't cruise @ full power so being on one engine will be a judgement call, if in order to maintain some kind of glide path better than complete engine loss you decide to reduce power on the one remaining due to engine temps going up regards power setting and airspeed.
My crazy thinking is three engines are better. Usually with three engines one will be in the center and will not adversely affect yaw and therefor not be included to any appreciable degree in drag losses due to the failure of either engine mounted on the side. So worst case if you lose a side mounted engine on an aircraft with (3) 17hp engines (51hp total) then you would have effective power of 37% of the two side mounted engines plus the full power of the center engine so 37% of 34hp = 12.5hp effective + 17hp center engine equals 29.5hp effective which is over 10hp better than a twin with a engine loss and much more room to reduce some power a bit to maintain temps.
A response would require some significant requirements definition, but even for talking points :I am curious what the responses would be if a new cheaper design came out utilizing small twin 2 strokes....yea or nay?
If you want the most efficient airplane and don't care about anything else then single engine is the way to go.==============================
With a Triple, your Cost & Weight goes up. Even most Commerical made Small Twins aren't being produced today. I haven't seen a Triple made since WWII.
The Lazair is a unique Plane account it was really more of a Motor Glider than an Ultralight and flew on (1) 9.5hp Engine, originally used (2) 5.5hp = 11hp.
Most Twins ever made don't share that Power to Weight Ratio!
A 2 Stroke or 4 Stroke can be built to be more Durable. You Can't Fix Stupid people who run out of Gas, forget to put Oil in the Engine/Gas, use cheap Low Octane Gas, don't change the Plugs, Fuel Filter, etc.
Just like when upgrading these Honda/Clones Singles, 99% only do the $400 worth of upgrade Mods, but yet the weakest Point on a 4 Stroke is the Valve Train. I would spend the extra $180-$200 and use the HD Billet Needle Bearing Rocker Arms. I would also use these Engine Coatings. This adds to the total Engine Cost, but you can do them yourself fairly cheap.
Don't think "reliability" is the term you're looking for. Adding a second engine only doubles the chance of an engine failure.Well, most engine setups end up being upwards $7-10k so was just thinking about cost vs reliability.
===================If you want the most efficient airplane and don't care about anything else then single engine is the way to go.
Twins are not produced because "they are inefficient, so is a triple", but it is inefficiency of a bygone era's opinion. There is a different type of efficiency gained with a three engine arrangement and that is the ability to make it to a runway if you have a loss of engine power or much better odds of it. I often see in the evening news a ga airplane accident and most of them are single engine. It isn't just because there are more single engine aircraft it is because a single engine aircraft has much less chance of making it to a runway than a multi-engine when there are engine problems.
I argue that a triple isn't a lot more expensive than a twin because the engines can be smaller than the twins engines and their smaller size offsets part of the expense. I also argue that a engine out in a triple is much easier to deal with than an engine out in a twin, because (unless you go to extreme sizes of engine on the twin) you will have more remaining power available with an engine loss with the triple and also less adverse yaw to control.
Since engines and aircraft are created by humans, any failure is thus human-related. Humans designed them, humans built components, humans assemble them, and humans operate them. On that basis, 100% of all accidents, not just engine failures, are "human related." Guess I should just delete my databases and relax.Notice, Engine Failure isn't really a problem, it's Pilot/Human Error for not Maintaining their Engine. I would say 99% of all Engine Failures are Human related.