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Engines to replace the dominance of Rotax

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GTX_Engines

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It is my understanding the inverted cylinder engines were popularly abandoned nearly 100 years ago for good reason...there's a better way to do it. The only good reason in the first place to do it was to lower the cowling height from the thrust line on tail draggers during ground ops. If that was such a big deal, then what was the problem with the radials? Seems enough of them made it to WWII and beyond.

It's really not that big a deal to give up a few inches of sight line over the hood in order to have a well-designed engine - especially in a trike gear FW.

Musing about starting from scratch to build a motor one would be otherwise well advised to stay away from what we have known for many decades to be a bad idea.

Just sayin'...
 

Pilot-34

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Hasn’t anything happened in the last hundred years to solve the problems with these engines?
Does a In-line have to be inverted ?
 

cluttonfred

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In-lines started upright and were inverted to improve visibility and aerodynamics, here are two variants of the DH.60 Moth series, one with the early upright engine and one with the later inverted engine. It did make a significant difference in both aspects.
De_Havilland_DH_60GIII_Moth_Major_img_0507.jpg
De_Havilland_DH-60_Moth_Melton_Vabre.jpg
 

PMD

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Six cylinder air cooled inverted with a selectable Mechanical supercharger
One of my close friends built a bushplane around that engine, and enjoyed it immensely. It was quite reliable and effective - but now a bear to support (he did a complete overhaul for second owner a few years ago, but was not a simple affair). BTW: that engine is set up not only for normal aspiration or forced induction, there is (was?) and aerobatic version and one could easily switch from normal propellor control to beta pitch version quickly and cheaply. Quite handy on floats to have reverse thrust!

IMHO: it was one of the best engines in its power class ever made.
 

Pops

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In-lines started upright and were inverted to improve visibility and aerodynamics, here are two variants of the DH.60 Moth series, one with the early upright engine and one with the later inverted engine. It did make a significant difference in both aspects.
View attachment 97353
View attachment 97352



Try hand propping the blue one after losing all the air.
 

cluttonfred

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Pops, I’m not sure what you mean by “losing all the air.” Quick tangent...I believe that the moth insignia on the side of the Swiss DH.60G III means it was actually built in the USA under license by the Moth Aircraft Corporation of Lowell, Massachusetts. Here’s another, the kids and me at the Nanyuki, Kenya airport with the actual 1929 DH.60GM Gipsy Moth featured in the film "Out of Africa.” It had just been reimported to Kenya and rolled out of the hangar after assembly and the mechanic and pilot were awaiting CAA permission for a test flight. That old plane had been around the world and back again! PS—I’m about 5’ 10” and both of my sons are now about 6’ 1” and my daughter 5’ 6” or so at 14. Time flies....

041D4FB7-5C95-4266-B4CF-7F69C639EF79.jpeg
 

PMD

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It is my understanding the inverted cylinder engines were popularly abandoned nearly 100 years ago for good reason...there's a better way to do it.

Musing about starting from scratch to build a motor one would be otherwise well advised to stay away from what we have known for many decades to be a bad idea.
You mean for instance with poppet valves, gasoline fuel and all of that stuff? Couldn't agree more: far, far better ways to do internal combustion.
 

Pilot-34

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It seems like a straight 6 built with all the internals of the in-line Ford 300 might be a good place to start.
Cast a new block out of aluminum with internal liquid cooling and a finned aluminum case And you might be on your way to a good direct drive aero motor.
 

EzyBuildWing

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Sydney NSW Australia
Solo Aircraft Engines produces Certificated, water-cooled 2-strokes. They're twin-cylinder, with belt-reduction.
Approx specs: 600cc, 60hp continuous, 6000rpm, 60lbs.
That's about 10cc/hp.....which is a pretty good "rule-of-thumb".
ArcticCat 800cc twin-cylinder water-cooled 2-stroke motor in Mosquito heli is good for about 80hp continuous.... = 10cc/hp.
So around 10cc/hp is OK for water-cooled 2-strokes in aircraft applications.
Of course spinning them faster increases fuel-burn and thus increases "energy-out", but at the cost of reliability and longevity.
ArcticCat produces a smooth 400cc single-cylinder 2-stroke with balance-shaft etc, which at 10cc/hp is good for 40hp continuous.
 

Pops

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I think he's referring to air starters, and running out of high pressure air. With the high thrust line of the blue Moth, it would indeed be a full bother trying to start it.
Exactly.
Very hard to hand prop. With the high pressure low volume air storage tank it just takes a very small leak to deplete the air for a start. Engine has a small air pump to keep the air tank pressure up when running.
Neighbors 1947 Stampe SV.4C with the Renault 140 HP engine. I have had to hand prop it due to an air leak.
 

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erkki67

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Vigilant1

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The need to get their story straight. The spec table says "up to 17 kW (23 HP) at 6500 rpm", but the graph shows a max ("100% TPS") of about 14.6 kw (19.5 HP) at 6500 rpm.
 

cluttonfred

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For the record, my interest in inline engines has absolutely nothing to do with mechanical superiority, just that so many of the great old planes I like had inverted, air-cooled, inline engines and it's pretty much impossible to replicate that look with anything else. Here are a few, I can come up with many, many more. :)

pt-19.jpgzaunkoenig.jpgf-380.jpgsi 202 hungary.jpgswift & comet.jpegmew gull.jpgC-684 Rafale.jpgike.jpg
 

Yellowhammer

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Like many, I’m not (psychologically) a Rotax fan; but they’ve stuck with the aviation hobbyist for decades now -- arguably refining the product and moving along as the application moves; usually to heavier, more-complex aircraft. The notion of the better motorcycle engines is appealing to me and power like the R-1 (I liked the Z11 series – Kawasaki) seem attractive, but unless you own a small machine shop and a modicum of skills to match, it isn’t something most of us can safely tackle from an airworthiness standpoint – it is one thing to chuckle through a power-out at 103 speeds, yet another to white-knuckle at LSA speeds and can be a whole lot more breathtaking when the stall speeds approach 60mph or so… and as Jab and UL (etc.) have shown, it is difficult to knock the Rotax cowboy off the saddle… I think about the only engine that has come close is the VW-Beetle in years gone by… but that was from an era when at least one shade-tree wrench in five actually has VW experience – not the case any longer, so while skilled folks may get an R-1, or such, nicely assembled, I don’t see enough interest/abilities/skills/passion to reach critical mass…

Poetry!
 

Yellowhammer

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For the record, my interest in inline engines has absolutely nothing to do with mechanical superiority, just that so many of the great old planes I like had inverted, air-cooled, inline engines and it's pretty much impossible to replicate that look with anything else. Here are a few, I can come up with many, many more. :)

View attachment 97428View attachment 97423View attachment 97427View attachment 97424View attachment 97426View attachment 97425View attachment 97429View attachment 97430
I too like the inline engine. I wish I could find an inline 2 or 3 cylinder four stroke about the same weight as the Rotax 582.
 

Yellowhammer

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The 582UL Engine is $5000 today plus you need the Cooling. I have never seen a 582UL used in Direct Drive though. Those Airframe manufactures have the Rotax 582, 192/914, Hirth's, Simonini's, MKZ, etc., to pick from. They also have some of the 4 Strokes to pick from today.

What four strokes are out there with the same weight as the 582? Or does such an animal exist?
Thanks for you're help!
 
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