154hp microlight engine

[Colibri49]

https://www.youtube.com/watch?v=UqZLsHa2XSE


Never mind the 450kg limit and fuel vs passenger load considerations. Just think of the climb rate and cruising at FL 100 at Vne !!

[733driver]

Impressive. Makes you wonder why stock Rotax engines are so expensive even though their technology is so simple. These guys offer a much improved Rotax with higher quality components at a comparable price to the closest comparable factory equivalent.

[Jan Olieslagers]

While the original design may be all too conservative, squeezing almost the double power out of the same engine block is imho itching for trouble.

Also: who says this is a microlight engine? My 450 kg craft is (slightly) overpowered with the stock 80 HP Rotax, 154 genuine real hp would be total overkill. OTOH in a 4-seater it might come in useful.

[Silvaire1]

The welded up built-up crankshaft made me smile - that's late 1970s to 1980s racing motorcycle technology. Often used where they were similarly getting high percentage power increases. Those types of crankshafts were superceded on four stroke motorcycles not long after.

Prediction of increased climb rate in this case is interesting, especially with a fixed pitch propeller. More peak power in conjunction with a different cam generally means less mid-range rpm power. When climbing a high speed plane with a fixed pitch prop you may be well below peak rpm with throttle fully open. Higher displacement can offset this effect, not all planes have such a large difference between cruise and climb speed, and some have constant speed propellers. So it depends.

[xrayalpha]

What were these type of crankshafts superseded by?

[Colibri49]

As instigator of this thread this will be my final statement. Does anyone here understand the expression "tongue in cheek"?

[Jan Olieslagers]

Negative. No such term in the PPL ground class neither in the ELP preparation training. ;)

[B2N2]

Just waiting for somebody to put a Hayabusa engine in a Light Sport.

[733driver]

As instigator of this thread this will be my final statement. Does anyone here understand the expression "tongue in cheek"?

I think your tongue in cheek comment could have been understood at least two different ways.

1. What a useless engine as any ultralight would be way overpowered.

or

2. Great engine but perhaps a bit over the top for an ultralight.

Perhaps it's just me but I wasn't sure which one you meant.

The guy in the video explains that the engine is used on auto gyros and even helicopters in addition to obvious applications such as home built/experimental airplanes.

I think its primary intended application is probably not your run off the mill ultralight/LSA.

[Silvaire1]

What were these type of crankshafts superseded by?

Multi-piece pressed-together needle bearing crankshafts were superseded by plain bearing one piece crankshafts on four stroke motorcycles, e.g. Japanese liter displacement inline fours. Prior to that, the technique of welding up multi piece cranks was used to make them more rigid for racing engines, emulating a one piece crankshaft, although it prevented them being disassembled for bearing replacement.

[gasax]

To add to Silvaire comments it also lead to a healthy after market in bespoke crankshaft manufacture. These days with so many turbo and supercharged engines you can buy 'off the shelf' high spec crankshafts and conrods for a wide variety of performance cars and bikes.

Built up cranks are a cheap and easy way to make them but obviously as you increase the power you approach their ability to withstand the forces. Get any sort of malfunction and things tend to slip, typically writing off the whole engine.