DrZoos Posted October 30, 2015 Posted October 30, 2015 This was on facebook yesterday...imagine the power to weight ratio... A honda CR500 puts out 60HP So this may put out around 240HP ?? Interesting.... 1 1
DrZoos Posted October 30, 2015 Author Posted October 30, 2015 i dunno, most CR500's with a new ring every now and then would make it past 500 hours pretty easy.... and with 240hp, you wouldn't be running it very hard very often... the big issue here would be how it could handle a heavy fly wheel/prop and crank shaft strength... I reckon this would only cost $5,000...so if i was a home builder id be considering it or variations at some point... 4 cylinders of two stroke is a lot more reliable than two or one... This could become a first world suicide vest 1
Yenn Posted October 30, 2015 Posted October 30, 2015 To get that HP from a 2 litre 2 stroke you would need a very small diameter prop.
Deskpilot Posted October 30, 2015 Posted October 30, 2015 Hirth F30! See below. http://www.rotaryforum.com/forum/showthread.php?t=3500
DrZoos Posted October 30, 2015 Author Posted October 30, 2015 hirth is 80-110 who would fly behind a four cylinders of two stroke for that rubbish HP This new two stroke has possibly 240HP 1
bexrbetter Posted October 30, 2015 Posted October 30, 2015 Horizontal twin "Twingle", air cooled Yamaha IT 490 barrels and heads on common crankcase would be the go, 60hp direct drive light as .... Modular in 60hp increments.
DrZoos Posted October 30, 2015 Author Posted October 30, 2015 hey bex the CR500 is 60hp what your thoughts on this 4cly 4 x 500cc what sort of hp would it get at the prop
Guest ozzie Posted October 30, 2015 Posted October 30, 2015 Johnson Evinrude had V4 2lts decades ago. The Martin jetpack is similar. Problem with these is the woeful fuel burn at full giddyup.
Brett Posted October 31, 2015 Posted October 31, 2015 :roflmao:Still in the right airframe and at a climb rate of 4000 fpm prob wouldn't need full noise for long
fly_tornado Posted October 31, 2015 Posted October 31, 2015 hirth is 80-110who would fly behind a four cylinders of two stroke for that rubbish HP This new two stroke has possibly 240HP without the same reliability issues the Hirth has...
eightyknots Posted October 31, 2015 Posted October 31, 2015 Johnson Evinrude had V4 2lts decades ago. The Martin jetpack is similar. Problem with these is the woeful fuel burn at full giddyup. I think the airborne time with a Martin jetpack is only a little over 30 minutes because the fuel burn is so horrendous.
DrZoos Posted October 31, 2015 Author Posted October 31, 2015 Johnson Evinrude had V4 2lts decades ago. The Martin jetpack is similar. Problem with these is the woeful fuel burn at full giddyup. Just got to fly in torrential rain to keep it cool
DrZoos Posted October 31, 2015 Author Posted October 31, 2015 The two stroke diesel would be interesting, but once you include the turbo or supercharger and valves you basically back to the weight of a four stroke, with some extra power and heat.
eightyknots Posted October 31, 2015 Posted October 31, 2015 The two stroke diesel would be interesting, but once you include the turbo or supercharger and valves you basically back to the weight of a four stroke, with some extra power and heat. Another matter is that petrol and avgas is about 720 grams per litre. Diesel fuel starts to approach 1 kg per litre. For a good sized tank full of fuel, the difference may be significant for a light aircraft. 1 2
eightyknots Posted October 31, 2015 Posted October 31, 2015 Another matter is that petrol and avgas is about 720 grams per litre. Diesel fuel starts to approach 1 kg per litre. For a good sized tank full of fuel, the difference may be significant for a light aircraft. I just looked it up to confirm: There are different grades of diesel fuel but the weight range is somewhere between 875 and 960 grams per litre. This is quite a bit more than petrol or avgas.
bexrbetter Posted October 31, 2015 Posted October 31, 2015 hey bex the CR500 is 60hp what your thoughts on this 4cly 4 x 500ccwhat sort of hp would it get at the prop You would need a PSRU and you would be looking at 170-180hp at 5000 rpm all day long with 4 pipes that take up a lot of room, maybe 150 - 160hp with just 2 pipes (that are still bulky). People quickly forget about the pipes you critically need to make good power from a 2 stroke, they don't weigh much but can be bulky and awkward to fit in place ...
Guest ozzie Posted October 31, 2015 Posted October 31, 2015 Just got to fly in torrential rain to keep it cool Problem is with cooling, the outboards have thin water jackets as they normally use fresh cold water all the time. Had a friend years ago that tried one in a racing sidecar and it never finished a race due to overheating and no amount of glycol on board fixed it. Went like a cut snake until it made tea tho.
RDavies Posted November 30, 2015 Posted November 30, 2015 What a great use for CR500 engines for those of us who are no longer able to ride one (in my case too many injuries by CR500). A great reliable engine. With long tapered expansion chambers, hanging outside the cowl, they will have a great torque curve. You would only need a CR1000 twin, or CR1500 triple for something the weight of most ultra lights.
Oscar Posted November 30, 2015 Posted November 30, 2015 The Suzuki F750 motor developed from the 'Water-bottle', (that shredded Barry Sheene at Daytona..) developed, from memory, about 145 HP. I have the porting dimensions tucked away somewhere; almost the only other change was the titanium Mikuni flat-slide carbies, for weight purposes, and very trick pipes.. A bog-standard Squeeky 750 was a stone-axe reliable tourer, with no nasty 'on-the-pipe' characteristics (unlike the Kwacka Mach III 500 triple!). The Kwacka engine was stuffed into a frame that was called 'benign, when parked with the engine turned off' but was generally accepted as being psychotically homicidal if moving. A water-cooled, twin-spark 750 - 1000cc two-stroke, with porting and exhaust tuned for the limited rev range required of an aircraft, could well be a viable concept. However, I suspect that by the time you have added the PSRU, the cooling set-up, and taken allowance for the higher fuel consumption in terms of MTOW/endurance, the advantages become very slim. Of all the manufacturers on the planet, Rotax has probably the greatest depth of data for both 2-stroke and 4-stroke engines across its range. Had it been a lay-down misere for 2-strokes, the 912 series (and derivatives) would not have been created. As it is, the 91X has many design characteristics common with lawn mower engines... but not the lack of valves. 1
Nobody Posted November 30, 2015 Posted November 30, 2015 The two stroke diesel would be interesting, but once you include the turbo or supercharger and valves you basically back to the weight of a four stroke, with some extra power and heat. That is the way that Wilksh Airmotive have gone with their engine: http://wilksch.net/ A very good write up of the engine in an RV-9 is here: http://www.kitplanes.com/issues/27_4/flight_reports/Wilksch_diesel-powered_RV9_9177-1.html Compared to a lycoming RV-9 it is Lighter and less fuel is used but with less power the speeds are slower.... 1
bexrbetter Posted November 30, 2015 Posted November 30, 2015 You would only need a CR1000 twin, I have long thought about a flat twin "Twingle" (twingle means that both cylinders fire at the same time, i.e. twin single) the flat twin layout for compactness and balance. Allows you to use one exhaust chamber, one carby or injector, etc. I would do it a little different though, direct drive with a whopping long stroke because as DrZoos says, by the time you add a PSRU the weight percentage difference gets smaller compared to a 4 stroke so keep the obvious weight advantage on your side.
Oscar Posted November 30, 2015 Posted November 30, 2015 The WAM 3-cylinder is pretty comparable with the Jab. 3300 for output. But it weighs 131 kgs installed, vs 83.5 for the 3300. ( prop hub forward excluded for both.)
Downunder Posted November 30, 2015 Posted November 30, 2015 Reed intake bex?...easiest I guess... I haven't looked too hard at the Rotax 582 but I guess it fires 180 degrees apart? (2 carbs) Separate crankcases but one rotary valve. Is that right? Going to get one heck of a pulse firing together but the stroke would smooth it out somewhat?
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