"Grindintosecond" (Grindintosecond)
04/30/2015 at 11:50 • Filed to: planelopnik
4
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"Grindintosecond" (Grindintosecond)
04/30/2015 at 11:50 • Filed to: planelopnik | 4
| 19 |
This is a 1/2 VW engine. That’s right, they cut the engine in half, cutting out the back cylinders and welded the case back together so only two cylinders exist. The purpose of such an engine is for ultralight or very very light aircraft, without spending twice as much money on expensive Austrian two-stroke power. “But, why?” you may ask. “Aren’t there other options already out there?” You may also ask that. Well, not without spending lots of money there isn’t, and the weight isn’t all that bad in the end!
This is basically an air-cooled VW beetle engine. Once the job is finished, the whole engine ready to fly weighs about 85 pounds. For those efforts, you have about 35hp@3,500 rpm. But, that’s not all. That’s the basic engine. We can build this up to 1200cc and 45hp with reliability, for about the same weight. It’s all displacement. This engine is in the same class as a Austrian Rotax engine that weights slightly less but also costs quite a bit more to run. It burns more fuel per horsepower, consumes added oil, has an overhaul recommended every 300 hours, (The VW hasn’t discovered how long it can run, some of them have gone 1,500 hours and run strong.) And has widely available parts for not much money at all.
Now there are less complex ways to do this without cutting and welding the case. It’s actually a magnesium case so cutting it and all of that work only saves you five pounds more. the true weight of a VW is the cylinders and heads and pistons, etc. Cutting those out of the equation take lots of weight off but what you’re left with is just two cylinders of a flat-four and it is balanced. they truly work in boxer fashion, out together-in together. any case pressure changes from that are taken care of by a pressure check valve so oil is never pumped out of the seals. Have a good look around one on a test stand. sounds buttery smooth.
So what’s it used for? Well, ultralights and small single-place planes. All single place planes really. Let’s start REALLY small with the Legal Eagle. Weighs 244 pounds. Talk about cheap flying.
Then the Hummel bird. All aluminum kit built plane. The same company makes quality versions of this engine as well in several power levels. this looks much better. (takeoff in 50s)
The Fisher Avenger is long the same lines of the Hummel Bird,
Have a nice long evening flight in an Avenger with a camera mounted on the pilot’s helmet. (in this vid he did loose the oil pressure due to overfilling it and the oil foamed up.)
TEAM mini-max, again very similar to the previous few.
You see, if you do the work, for $2,000 or quite a bit less and with a few hand tools and some friends (or connections with labor and beer) you can have some good reliable power for your small inexpensive kitplane. (The bigger power options start costing more because of some aftermarket parts, such as that 1200cc 45hp model you can but direct ready to fly for $4500.)
this is seriously cheap flying, especially if it’s an actual ultralight where you don’t need a pilot’s license, just a few lessons.
ttyymmnn
> Grindintosecond
04/30/2015 at 11:59 |
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Fascinating. Thanks for the write up.
McMike
> Grindintosecond
04/30/2015 at 12:02 |
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I love it.
E. Julius
> Grindintosecond
04/30/2015 at 12:03 |
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Very cool. I could definitely see myself getting into ultra lights when I’m older. I always see tons of them over the country by my parents house over the summer, saw a bunch of them growing up too. Very inspiring.
BobintheMtns
> Grindintosecond
04/30/2015 at 13:08 |
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Pretty cool... although I’m curious as to why they don’t just source an engine from a bmw motorbike, versus cutting a vw motor in half....
And fun-fact, bmw boxer motors originally started as the motor for bmw airplanes. But after WWI, Germany wasn’t allowed to build airplanes (and other potential war-machines). So after some head-scratching, instead of closing down, bmw decided to try their hand a building motorcycles......
Frank Grimes
> Grindintosecond
04/30/2015 at 13:18 |
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so i dont get it why is two more cylinders with much more hp bad?
PilotMan
> Grindintosecond
04/30/2015 at 13:28 |
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Belite would be my favorite, folding wings for easy trailering.
And a four stroke sounds a whole lot better than a 2 cycle Rotax.
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Grindintosecond
> Frank Grimes
04/30/2015 at 14:26 |
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Because a full four-cylinder 80hp VW installed weighs 150 pounds. For these ultralight or very light planes, 150 pounds is too much engine and for an ultralight, makes the plane illegal as there are performance and weight limits to classify a plane as that. So, doing a half version saves 60+ pounds and that’s important on a plane that only needs 35-45hp.
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Frank Grimes
> Grindintosecond
04/30/2015 at 14:40 |
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nope more hp is better even if the wings fall off.
edu-petrolhead
> Grindintosecond
04/30/2015 at 16:12 |
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Fun fact: The Brazilian Gurgel BR800 used half a VW engine, called the Enerton engine :)
BoxerFanatic, troublesome iconoclast.
> Grindintosecond
04/30/2015 at 18:18 |
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Ummm....
BMW air-cooled boxer twin, or Moto Guzzi air-cooled V-twin.
Those seem like other options than chopping a VW flat four into a flat twin..
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Grindintosecond
> BoxerFanatic, troublesome iconoclast.
04/30/2015 at 20:11 |
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The BMW opposed engine at that RPM range has the same power if not slightly less torque in direct drive, it also weighs quite a bit more. Running the transmission reduction drive gives you 90hp but also weighs twice as much as this half-VW (160+ pounds) The Moto Guzzi has one disadvantage to it-that being it’s V-twin configuration being upright and vertically a visual blockage to the pilot’s line of sight. this means if it’s mounted lower so the pilot can see, the prop line is now lower and closer to the ground increasing prop strike chances or making a modification to the landing gear a whole other issue that upsets the ground visibility.
So, there’s the reduction drive option to correct any of these prop location issues. It’s more maintenance, more complexity, and debatable reliability as any auto conversion engine used typically has serious reduction drive issues in the long term. Besides, reduction drives make more weight. Here is a Guzzi powered ultralight for your time.
It sounds glorious, I do give you that. The Guzzi has really two displacement options, about the same as a half-VW, or really big 1400+ sizes and those are heavier. However when it comes down to power/weight ratio and simplicity, there is a reason the half VW is orders of magnitude more popular. The goal is parts availability and cost, weight, and power required for that price. Ultralights don’t need big fat power because the law limits their maximum speed.
full flat-4 VW engine as an airplane engine is 150 pounds installed.
Half-VW is 85 pounds.
This is just a popular and simple and cost effective option people can do themselves. the engineering has been done already and it’s reliable. Doing it with a Guzzi would mean you have to do quite a bit of engineering yourself. It’s been done but not with as wide range of enthusiasm. I personally would LOVE to run a big guzzi direct drive and inverted for the prop line. It would be a good engine once the oiling issues witht that are solved.
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Grindintosecond
> edu-petrolhead
04/30/2015 at 20:13 |
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I was not aware of that engine... water cooled at that!
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Grindintosecond
> BobintheMtns
04/30/2015 at 20:15 |
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the BMW motorbike engine is heavier by quite a bit. Parts cost more by quite a bit as well. the whole point is cheap and effective power for planes that are speed limited by law.
Zipppy, Mazdurp builder, Probeski owner and former ricerboy
> Grindintosecond
04/30/2015 at 22:03 |
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I remember visiting a factory that made the Quasar Lite, a lightweight plane that could run on cane sugar ethanol. runs on a flat-twin HKS 700E with 60 HP, it is the same idea pretty much. HKS made a turbo engine too.
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BoxerFanatic, troublesome iconoclast.
> Grindintosecond
05/01/2015 at 10:43 |
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Interesting. I didn’t realize that the half-VW was that light, and I would have figured the BMW boxer to have been lighter without the gearbox involved.
A moto guzzi’s splash-oil-bath cooling in the cylinder heads would be quite a challenge in an inverted position, or even for any sort of acrobatic flight, come to think about it. I get the issue with prop axis height above the ground to prevent prop strikes, but I wonder if perhaps a pusher-prop behind the pilot might be helpful, to have a proper height, with lack of visibility impedance.
However, I have to say... despite my user-name, I think I would prefer a Wankel Rotary over either of those boxer engines, for constant high-speed, high-power use.
An ultralight might be able to use the 450cc, 80lb, 65 horsepower version... and a slightly larger experimental or light sport aircraft might do well with the 1300cc 2-rotor, 12olb, 150hp engine.
I have been interested in rotary powered small aircraft since reading some of the material that Paul Lamar published on his website. http://www.rotaryeng.net
His theories on turbine compounding are quite interesting.... A rotary with a blow-down turbine compounded into the output shaft, and also driving a CVT-driven variable supercharger like a Rotrex unit matched well to the pressure and volume characteristics of the rotary’s intake, would be very interesting, and about as close as it would get to a small turboshaft, without actually being one.
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Grindintosecond
> BoxerFanatic, troublesome iconoclast.
05/01/2015 at 12:20 |
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The wankel aircraft dream is alive and well and constantly pursued. The issues are reduction drive reliability, and engine reliability. that’s fine. they spin at higher rpm and are smooth about it. They simply don’t last as long as a piston four-stroke. they need more frequent overhaul times and they run hot. The engine itself requires quite a bit of exhaust tubing for scavenging of the gasses, something the engine was built to do. The cooling system and gearbox and exhaust plumbing and heat shielding all add up to weight to a point where a simple aircooled direct drive engine weighs the same or less. If weight isn’t an issue, then sure go rotary.
Turbos in aircraft. They run HOT! A typical aircrat turbo engine is turbo-normalized to a point. Where it maintains sea level power all the way up to 15-25k feet. So the turbo has to work harder and harder the higher it is as the intake air is thinner (50% density or less at 18k feet) so the turbo will be pumping a pressure ratio of around 3:1....which at sea level would be like pumping 35-45 psi. We have seen pictures of dyno engines glowing their cherry red turbos on boost like that....and at that altitude they are running that way sustained for hours. So the theory is sound for turbo-compounding. the engineering to make it work temperature wise and exhaust wise is massive especially on an engine that runs crazy hot exhaust temperatures to begin with. There are stories of Jim Downing’s Kudzu Mazda cars at Daytona spitting out a foot or two of blowtorch out the exhaust while on the high banks. I can’t find any pictures of that yet.
It’s hard to make the Mazda work on a power-weight ratio better than a regular certified engine, and be just as efficient. Besides, the Mazda is robust and created 400hp per rotor at LeMans but that wasnt for two hours straight, it was for 30 seconds at a time absolute maximum. Look up the pond racer’s engine problems when they tried to make a racing engine do that for fifteen minutes at a time.
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BobintheMtns
> Grindintosecond
05/01/2015 at 12:20 |
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Yeah, after I posted that I was thinking about how heavy my airhead’s motor is.....
JPerry
> Frank Grimes
05/05/2015 at 13:15 |
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I know a guy who put a full VW in his legal eagle. He basically redesigned every part of the airframe. Kind of a chain effect thing.
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JPerry
> JPerry
05/05/2015 at 13:34 |
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Correction: Affordaplane