Discussion in 'GEO / Suzuki' started by divad_strebor, Jun 12, 2008.
There you go then. Many of the early Franklins were designed for use in helicopters.
I have both a Hayabusa and Kawasaki ZX-14 motorcycles. The Kawasaki is a much smoother engine than the Hayabusa. The Hayabusa has much better mid range torque and considerably better fuel efficiency.
I would think that a choice worth considering is a engine from the Kawasaki ZX-14 Concours motorcycle. It has variable cam timing and is tuned to have more mid range torque. Otherwise I might consider the ZX-14 if vibration is an issue and have a special set of cams ground to shift the power curve downwards. If vibration is not an issue the Hayabusa engine is an extremely solid one (I have a turbocharger on mine that makes 300 hp and it's rock solid). I can't see paying $8500 though.
The Kawasaki ZX-10R could also be a good engine to convert for flying, it is light (less than 60kg) and with RAM air has some 200HP. Add a turbocharger, it goes up to 250HP and then, the sky is the limit. The only problem is the turbo chargers aren't cheap and the used ZX-10R engines aren't easily found...
Just wondering how a CVT (a light one) could do the PSRU job...
I did a math exercise on the CVT, somewhere in this forum before,
The CVT will keep the engine RPM up so it deliver 100% power, it is about 90% efficient or was it 85%?, so it loose or lose? 10%-15% but can run the propeller up to say 95-96% of max at climb, a fixed pitch-fixed gear set-up will have 80-95% rpm and power, the gearbox rob 2-5%
So at climb, the CVT can have a + but at cruise the fixed gear wins, on a light fast plane with a small (relative) engine I honestly think the CVT can be useful.
Question is if it is up to continous power of 60-80%
At cruise the fixed gear version will save 10% fuel. = a-lot
For the few minutes (if it's not seconds) before the engine will desintegrate, yes it is...
What about weight penalty ? (if any)
Cost will be higher for sure!
And do you have an specific CVT in mind?
There is a guy making tests, he is on this forum too, look for it in this forum. I forgot his name right now.
If I remember correctly it was safe for a few seconds (less than 10) at 250HP, around a minute at 220HP but it could endure quite a long time at something just below 200HP.
There is also a turbo ViJa engine (same as the ole GSX-R 1100 engine) that is 200HP but limited and reduced to 160HP for safe continuous use. It is a bit heavier though, at some 88kilos.
it will be good for this aircraft
View attachment 20135
Well that depends on your perspective of 'flying for hours' as opposed to riding for hours...
There are 2 bikes that have made more than 1 million kilometers in my country, the Yamaha FJ 1100 and the Suzuki GSXR 1100. Their owners rode them for many years to achieve that and documented the repairs and service they made, which we others find very informative and offer a different perspective to the one you wrote. The FJ1100 develops a maximum of 125HP at 9000rpm and the GSXR1100 150HP at 10000rpm at the crankshaft IF they are well tuned. At around 80% power, the FJ1100 is at 7200rpm with a bit more than 100HP while the GSXR1100 provides a bit more than 140HP at 8000rpm. They can both run for hours and years at 80% power if they are maintained well. Service is needed according to the specs and maintenance, service and repair manual, and only some models (year and design dependent) are the most appropriate for long runs. The Suzuki GSXR1100 engine and it's Bandit 1200 variant are being converted for aircraft use by a French company called VIJA engines. With the right reduction ratio these engines are more fuel efficient, have more power and endurance than most Rotax engines put in a motorcycle frame.
The problem is that these engines are not cheap to manufacture, when they were sold in the late '80s and the beginning of the '90s the Japanese motorcycle manufacturers were struggling to compete and sold the engines at almost 00% profit. The GSXR1100 crankcases sold at salvage yards are limited and once the parts are gone it will not be cheap to buy such engines. The VIJA 120HP engines are sold at €15k + VAT which makes this engine a bit expensive compared to the cheaper and less efficient Rotax engines. It all comes down to price, there are even more powerful engines developed on the same GSXR/Bandit/Hayabusa engines and some produce 400HP continuous as the H1 of Hartley or the V8 RPE of Radical Performance Engines with weight around 90 kilograms (a bit less than 200LBS). The standard Hayabusa or GSXR engine bored to a larger diameter (1300-1600ccm) develops 200HP without the turbocharger and from 250HP to 400HP with one at the weight of around 60kilograms. Will it ever be cheap? No. The new parts needed are expensive and work that has to be done is quite sophisticated. That is why we do not see many of them motorcycle conversions.
Converting a GSXR1100 engine to PERFORMANCE aircraft use needs five different segments to be done. One, removal of the gearbox which is adjacent to the crankcase by either machine cutting it or machining a completely new crankcase. Second, making a dry sump system with additional oil pathways for inverted and knife edge sustained flight so oil could keep constant flow (even though there are some amazing cases of riding a GSXR without oil for half an hour without damage) for lubrication. Third, boring the cylinders to a larger bore and adding different pistons so the compression ratio would be lower for adding the turbocharger and having more efficient fuel burn. Fourth, adding the turbocharger and fuel injection system with a Power Commander with great care about airflow lines into the system and exhaust. Last, making a reduction power drive for the transmission of power from the crankshaft to the propeller axis. In other words, at least 2 years of work and dedication to produce a 200HP constant and 250HP peak engine. The good part is that such an engine has around 150Nm torque and around 125HP at 6300rpm (70% rpm) with a fuel burn of around 8 liters per hour (and almost double that consumption at 80% rpm). The bad part is you need lots of dedication, sacrifice and money to make such a conversion.
To conclude, there are SOME motorcycle engines which are worth converting to aircraft use, specially the GSXR1100 oil cooled '89-'92 model. But if performance is not needed it is more affordable to either buy a VIJA engine or see if some of those producing the conversions like RPE (Powertec GSX-R Series 4 | Powertec Engineering - race-winning engines) does models that would be suitable for aircraft use in your area. But if time and money are issues, skip the idea entirely and go for the cheaper engines. In the end, it all comes down to how much time you can afford, if you know what I mean...
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