Why not more motorcycle engines?

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

Jay Kempf

Curmudgeon in Training (CIT)
Supporting Member
Joined
Apr 13, 2009
Messages
4,592
Location
Warren, VT USA
jay...what if you took two of the four props and put two of them in tractor at the wing tips for full time normal cruise, but the power level is tied to the joystick roll. now you have a roll control system that is effective at very low airspeed...lack of low speed roll control is the number one killer of pilots and lo demas, as i understand it. put the other two props wherever, for max thrust applications. it took a second look to see that i hijacked this thread from motorbikles to liteweight diesels. unless the bike was a series hybrid it wouldn't work for a bike, but it would work for a car(or better yet,an airplane). hence the hijack. the diesel thought is ideal in converting fuel weight into thrust, hence a lower gross weight aircraft at takeoff. also, spin the tip props counter to the rotation of the tip vortex and you reduce vortex drag for a higher apparent aspect ratio. a whole lotta stuff converging around this hybrid concept. daveed'

Blown tip vortex. You should run for a patent on that. I think you have something. Asymmetric thrust on the other hand and hanging on thrust at low speeds sounds like a guaranteed opportunity to be behind the power curve at all times when slow with the potential for thrust whiplashing of sorts.
 

Daveed'

Active Member
Joined
Apr 25, 2010
Messages
43
Location
cincinnati, ohio, ohio
jay...it's how the flying pancake worked. it is a device for when you're already behind the power curve, ie,

when you're flaring for landing and you get gusted. it beats a blank, as they say. this system would be asymetric when the authority vanishes with your ailerons. whiplashing pio is possible no doubt. the question of control needs to be explored before going into the math. you patent it and we'll split the bullion. daveed'
 

StarJar

Well-Known Member
Joined
Sep 6, 2011
Messages
1,723
Location
El Centro, California, USA
May I suggest that we start a new thread based on Karoliina's concept of an engine/s turning an alternator/s which power an electic motor/s. I think with some research we could at least theorize some workable setups.

These could then be expanded on, with other applications, if someone wanted to use the idea, in other threads.
 

PTAirco

Well-Known Member
Joined
Sep 20, 2003
Messages
3,733
Location
Corona CA
jay...what about the jumo diesel concept? daveed'
Not sure what exactly you're driving at with the Jumo-type of engine. The Jumo, by the way, does not have piston like a barbell. They are quite conventional. You're talking about a crosshead type of piston/cylinder arrangement like you find in many ship engines. All of these engines have some great advantages in their particular application, but in my opinion are the wrong choice for a hybrid concept like discussed here. The whole point of using the motorcycle engines is that they have such an exterme power to weight ratio and relatively low cost, it might just completely negate the extra complexity and reduced efficiency of using such a drive train. The Jumo-type opposed piston engines are large, heavy, slow turning engines and best suited for large, long range aircraft. Although there is a vast amount of room for improving these, I believe they are best suited to driving propellers directly, not through generators and electric motors.
 

Attachments

  • fm engine.jpg
    fm engine.jpg
    82.3 KB · Views: 816
  • jumo internals.jpg
    jumo internals.jpg
    23.8 KB · Views: 1,640

karoliina.t.salminen

Well-Known Member
Joined
Oct 7, 2008
Messages
407
Location
Finland
Starjar: it is not alternator though. The alternator word comes from alternating current. I was talking about brushless DC generator.
Splitting the hairs maybe?
Can you please post link to the new thread so I can find it.
I have to admit in the beginning that there is downside for the generator + electric motor drive: even if the brushless DC motors are fairly lightweight for their power output,
it will add many tens of kilograms when we are talking about power in the realms of 200 hp. So it comes into question comparing the electric drive system weight
and reliability (and cost) to gearbox and shaft and couplings -weight and reliability (and cost). This will determine how good idea or bad idea it is.
What we are talking realistically here is that the generator needs to be custom brushless DC motor with custom brushless DC controller. There is no such thing available from shelf.
The generator-motor in Toyota Prius (that is the biggest this kind of of the shelf part I know of) is not for this many horsepowers. Similarly the motors driving props will require custom
controller (ESC) that will have much more sophistication than RC-planes commonly have. Also if batteries are used, there needs to be electronics to monitor per cell voltage.
Hundred cells in series would mean hundred cells to be monitored (and shut down if cutoff voltage is reached). It is very easy to ruin lipo so that the ESC does not know per cell voltage, but knows
the whole battery voltage, and it results exploding/broken battery. Destroyed one 6S battery (22.2 volts in 6 cells series) for my RC plane last weekend this way. All seemed good until I landed it.
One cell had dropped to 1 volts which is so low that it possibly can never work again (next discharge cycle may even explode it).
 

timberwolf8199

Well-Known Member
Joined
Sep 3, 2011
Messages
281
Location
Grand Rapids area, MI, USA
Karolina, Orion's post has a link in it. If it doesn't work look for the new thread under the title "Hybrid Power: IC engine to generator to motor" it is in the same discussion group as this thread (General Auto Conversion).
 

DangerZone

Well-Known Member
Joined
Sep 5, 2011
Messages
2,183
Location
Zagreb HR
Some out of the box thinking using some little imagination: the BiPod-way (or the way I blogged about it some years ago already):

I have been thinking also about motorcycle engines since I started driving motorcycles, and got sort of immersed into how light and powerful they can be.
It seems consensus is that gearbox is not gonna work very well. Gyroscopic loads et cetera.

...

So lets take an example. Suzuki Hayabusa engine or maybe engine from Kawasaki ZX10R. Hayabusa has around 180 hp power output and weights about the same as Rotax 912.

...

I would estimate that the longevity at 27% power would be good enough for airplane use, especially considering that there is an enormous price difference between airplane engine and such motorcycle engine. I have seen (a bit used from broken bike) engines sold for 2000 euros. If Rotax 912 costs almost 20000 euros and Lycoming something 40000 and bigger models reaching up to 100000, if we take that kind of budget and buy 2000 euro engines, the lower TBO does not matter so much if the engines are just changed more frequently before they wear out enough to stop for catastrophic failure.

Etsuo Yokouchi was inspired by WWII aircraft fighters when designing the GSXR 1100, the precessor of the Hayabusa. He resolved the problems of heat and reliability and some GSXR 1100 machines made more than a million kilometers with regular service and changing the parts according to the service and repair manual. The Hayabusa has a larger bore and added water cooling for continuous high rpm usage and is somewhat 'beefed up' for turbo conversion use. Yet the GSXR 1100 engine cases ('86 - '92 oil cooled) are a better choice for an aircraft engine conversion. Someone mentioned the French ViJa engines which are an exact copy of the Suzuki GSXR 1100 and Bandit 1200 engines.

An oil GSXR engine can be turbocharged and some run up to 260HP peak and at 200HP even in continuous use. Yokouchi designed the SACS oil cooling system to be 5 times more efficient than actually needed for the engines at 150HP and some 10000rpm continuous use. That is the reason why these engines still run after so much heavy abuse by those who converted to turbos. But, the price of such a conversion is quite high. New stronger pistons, cylinders, piston rods, cams, a whole bunch of reengineering has to be done so the engine could run reliably at such high power. Add a turbo with all the air and exhaust pipes and you come to the price of more than €10k for the basic model without the dry sump. Want the dry sump too? Sure, add another €5k. Wanna get rid of the gearbox and have a reductor for aircraft use? No problem, just add another €5k. Sum it all up and your 200HP continuous GSXR engine is €22k.

And on top of all that add 2 years of development, engineering, machining and all other fun stuff when rebuilding such an engine. So yes, it is feasible, but who is gonna have the time, money, will and guts to do it? Just a few enthusiasts, if you search the internet you will see a whole bunch of people converting these good ole engines for some high power use. At first people say 'wow' and then after a few months they start talking and talking, questioning if they are not 'kept upo to date' about the project. They start questioning reliability, performance, everything. Just like in Mad Max's Road Warrior movie, people talk and talk, without any specific goal until some flame wars start on the net and the beautiful idea turns to mud after a few bad words. Then those who have done the conversion realize it is wiser to enjoy moments with the engine than to take part in such useless debates. Maybe that is the reason why we do not see more of motorcycle engine conversions for aircraft use?
 

girodreamer

Active Member
Joined
Nov 25, 2020
Messages
43
A 1000cc sport bike engine weighs 150lbs dry and produces 170hp. Why not reduce rpms to bring it down to ~125hp and have a package that weighs under 200lbs?

A suzuki 1300cc weighs 20lbs more an gets another 20hp running at a lower rpm for an extra 20lbs. And people modify those to over 500hp, seem like 150hp and ~220 lbs would be doable.

Is it the rpm or packaging issues? Stock motors are used for racing, so they should be fairly durable. Maybe not 2000 hours durable, but they are also cheap to replace. the built in transmission could even be used as a psru.

What issue am I missing?

I know some smaller engines (eg BMW) have been used in lower power applications, but haven't seen the newer high power ones used.

Hi,
there are, this french gyro built by Michel Cros, has flown for 20 years at least with a suzuki,

 

Jimboagogo

Well-Known Member
Joined
Jan 24, 2021
Messages
50
Etsuo Yokouchi was inspired by WWII aircraft fighters when designing the GSXR 1100, the precessor of the Hayabusa. He resolved the problems of heat and reliability and some GSXR 1100 machines made more than a million kilometers with regular service and changing the parts according to the service and repair manual. The Hayabusa has a larger bore and added water cooling for continuous high rpm usage and is somewhat 'beefed up' for turbo conversion use. Yet the GSXR 1100 engine cases ('86 - '92 oil cooled) are a better choice for an aircraft engine conversion. Someone mentioned the French ViJa engines which are an exact copy of the Suzuki GSXR 1100 and Bandit 1200 engines.

An oil GSXR engine can be turbocharged and some run up to 260HP peak and at 200HP even in continuous use. Yokouchi designed the SACS oil cooling system to be 5 times more efficient than actually needed for the engines at 150HP and some 10000rpm continuous use. That is the reason why these engines still run after so much heavy abuse by those who converted to turbos. But, the price of such a conversion is quite high. New stronger pistons, cylinders, piston rods, cams, a whole bunch of reengineering has to be done so the engine could run reliably at such high power. Add a turbo with all the air and exhaust pipes and you come to the price of more than €10k for the basic model without the dry sump. Want the dry sump too? Sure, add another €5k. Wanna get rid of the gearbox and have a reductor for aircraft use? No problem, just add another €5k. Sum it all up and your 200HP continuous GSXR engine is €22k.

And on top of all that add 2 years of development, engineering, machining and all other fun stuff when rebuilding such an engine. So yes, it is feasible, but who is gonna have the time, money, will and guts to do it? Just a few enthusiasts, if you search the internet you will see a whole bunch of people converting these good ole engines for some high power use. At first people say 'wow' and then after a few months they start talking and talking, questioning if they are not 'kept upo to date' about the project. They start questioning reliability, performance, everything. Just like in Mad Max's Road Warrior movie, people talk and talk, without any specific goal until some flame wars start on the net and the beautiful idea turns to mud after a few bad words. Then those who have done the conversion realize it is wiser to enjoy moments with the engine than to take part in such useless debates. Maybe that is the reason why we do not see more of motorcycle engine conversions for aircraft use?
Engine technology and reliability have certainly come a very long way in the last 20 years and that alone makes bikes, and snowmobiles even more viable as engine sources. That brings it down to the psru design which is often left to the builder. If you are confident in your engineering skills, go for it.
 

pfarber

Well-Known Member
Joined
Feb 21, 2019
Messages
1,054
Location
Dollywood
Motorcycle engines (high power ones) have high piston speed at high hp area. You can build aircraft engine for those ones, but engine wear much faster than conventional aircraft engines. Piston speed add piston travel (miles/ hour),friction and G forces and that will reduce your TBO.

Average piston speed that exceed 15/m/sec (50/feet/sec) start to be unreliable for long time use. Here is piston sped calculator, run some rpm level/ stroke and you know that speed:

Piston Speed Calculator - Universal Entry

...and engines like Speedway bikes have close to 30/m /sec piston speed...those will last approx one hour running time at that speed because fatigue of piston and overall stress....
Stop using airplane metrics on auto conversion.

I couldn't give a rip if I have to rebuild an engine every 500 hours as for most people thats over 10 years to fly that much.

You have to spend about a grand PER MAG every 500 hours and no one bats an eye. Yet rebuild an engine in 500 at a cost of 2-4k is somehow inconvenient.

Make it inexpensive and people will do it
 

Dan Thomas

Well-Known Member
Joined
Sep 17, 2008
Messages
7,498
Stop using airplane metrics on auto conversion.

I couldn't give a rip if I have to rebuild an engine every 500 hours as for most people thats over 10 years to fly that much.

You have to spend about a grand PER MAG every 500 hours and no one bats an eye. Yet rebuild an engine in 500 at a cost of 2-4k is somehow inconvenient.

Make it inexpensive and people will do it
I did mag inspections in a bit over an hour. The 500-hour interval is an INSPECTION, not an overhaul, which happens at engine overhaul.
 
Top