Yamaha Apex internal gear reduction.

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Ally Wilke

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Joined
Jan 19, 2021
Messages
51
The Yamaha 3 cylinders as used in the Nytro snowmobiles and others. The link to the new engine I gave you above is it.
We are looking at a possible winner here.The 3 cylinder does not have a gear reduction in the engine like the Apex 4 cylinder. The triple spins at more belt friendly RPMs than the 4 cylinder, so it doesn't need it for the sleds. There is a gear reduction in the transmission before the clutch.
 

cblink.007

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Joined
Jul 7, 2014
Messages
632
Location
Maryland, USA
Almost all snomobiles are belt driven to the cementrifical clutch.
The centrifugal clutch is coupled up to a torque convertor, which is a belt drive.

The thing I am trying to do is get this reliable engine to be cost effective for home builders.
I'm 100% onboard with that, but we are trying to tell you the answer is already there. So what exactly do you bring to the table on this, except for brazenly discrediting us who have done alot of work on this plant already? Why such an attitude? There is no need for that here.

Until recently, my engineering group had a YG4i, converted and on the test stand and running, for under $7,000, including prop, extension shaft, exhaust, cooling, electronics and prototyped mount. Pretty difficult to get below that price point, and we got the sled (as Yamaha does not sell Apex crate motors, kart plants notwithstanding) for under $1,500 at an estate sale. Rebuilding, conversion parts and FWF accessories add up quick.

Yes, we are always trying to trim costs. However, doing a modification to an already proven dynamic component-laden system, such as a plant like this, can potentially become a convoluted & expensive endeavor in a hurry, and could have a seriously adverse impact to mechanical reliability, performance and or safety. We converted and prepared our YG4i precisely to the instructions, and, while capturing vibration spectrum data on the test stand, we experienced a catastrophic engine failure well below redline due to oil starvation, and we have a Yamaha factory-trained and certified master mechanic on our team who led the rebuild & conversion. Freak accident, but it happens. We are still performing an EI on the engine, but due to very limited future availability of the Apex, we are looking to another power solution for our project. I would advise looking at their 3 cylinder plants...

Also, @wsimpso1 is a HIGHLY experienced engineer, much like many of us here. This forum possesses hundreds of years of engineering, fabrication, operational and maintenance experience, and likely well over a hundred thousand flight hours experience at the controls. Some here hold advanced degrees and are fully trained experimental test pilots, while some are just getting started. We welcome all. Don't be quick to dismiss us. We state what we do for a reason. Airplanes are indiscriminant creatures that can and will maime & kill if something isn't right. Four close friends of mine bought the farm not of their own accord while operating aircraft, and I visit their markers annually.

Have a drink. Chill. Read. Learn. Have fun. We're only trying to lend you our experience and mentorship, as it will only have the effect of making your experience in the E-AB world a productive and memorable one.
 

Ally Wilke

Well-Known Member
Joined
Jan 19, 2021
Messages
51
The centrifugal clutch is coupled up to a torque convertor, which is a belt drive.


I'm 100% onboard with that, but we are trying to tell you the answer is already there. So what exactly do you bring to the table on this, except for brazenly discrediting us who have done alot of work on this plant already? Why such an attitude? There is no need for that here.

Until recently, my engineering group had a YG4i, converted and on the test stand and running, for under $7,000, including prop, extension shaft, exhaust, cooling, electronics and prototyped mount. Pretty difficult to get below that price point, and we got the sled (as Yamaha does not sell Apex crate motors, kart plants notwithstanding) for under $1,500 at an estate sale. Rebuilding, conversion parts and FWF accessories add up quick.

Yes, we are always trying to trim costs. However, doing a modification to an already proven dynamic component-laden system, such as a plant like this, can potentially become a convoluted & expensive endeavor in a hurry, and could have a seriously adverse impact to mechanical reliability, performance and or safety. We converted and prepared our YG4i precisely to the instructions, and, while capturing vibration spectrum data on the test stand, we experienced a catastrophic engine failure well below redline due to oil starvation, and we have a Yamaha factory-trained and certified master mechanic on our team who led the rebuild & conversion. Freak accident, but it happens. We are still performing an EI on the engine, but due to very limited future availability of the Apex, we are looking to another power solution for our project. I would advise looking at their 3 cylinder plants...

Also, @wsimpso1 is a HIGHLY experienced engineer, much like many of us here. This forum possesses hundreds of years of engineering, fabrication, operational and maintenance experience, and likely well over a hundred thousand flight hours experience at the controls. Some here hold advanced degrees and are fully trained experimental test pilots, while some are just getting started. We welcome all. Don't be quick to dismiss us. We state what we do for a reason. Airplanes are indiscriminant creatures that can and will maime & kill if something isn't right. Four close friends of mine bought the farm not of their own accord while operating aircraft, and I visit their markers annually.

Have a drink. Chill. Read. Learn. Have fun. We're only trying to lend you our experience and mentorship, as it will only have the effect of making your experience in the E-AB world a productive and memorable one.
There is a chain drive in that torque converter on snowmobiles.What I am saying is we may be able to eliminate the need to buy your $3,500 psru and save even more money or eliminate running 2 gear drive reduction units on an emgine for less mechanical drag and more reliability.
 

TFF

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Joined
Apr 28, 2010
Messages
14,518
Location
Memphis, TN
I think without casting a new block, the simple answer is no. The big gear would need to be even bigger than the skytrax box to slow to a prop speed if you wanted to get rid of intermediate gears. The ratio is pretty simple to figure out. If the output shaft gear is so big, the corresponding gear will be the ratio bigger. You know that. The next question is are they strong enough at that size? Eyeball engineering means it’s going to have to be at least as big as the next guy’s, if they got it right. Many times they underestimate it, being optimistic. It’s going to be pretty hard to beat something that works, because there is a reason it works.
 

slociviccoupe

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Joined
Apr 1, 2011
Messages
366
Location
Palm Bay Fl.
The newer 1.8 engines do not have any reduction drive. Also the 3 cylinder tr1 in the ex and vx line of watercraft that is similar to the 3 cylinder in the yzx side by side.

Also keep in mind with addition of a water pump and a new exhaust header the supercharged 1.8 ski engines make 230hp at 8400 rpm. But they are thirsty. Thats on 6# boost at sea level. The svho engine on 11# maes yamahas quoted 260hp. But been known to make more near 300hp on a dyno.
All out of 1812cc with supercharger.

Yamaha has yet to put this combo on a sled. But thry do have the turbo model i think. Not sure what engine though.
 

Ally Wilke

Well-Known Member
Joined
Jan 19, 2021
Messages
51
I am liking those HP numbers and the 8,500 rpm is getting closer.There are things we can do to engines to make HP at lower rpms.I was looking foreward to beating a sled like a red headed step child for a bit until I needed the engine.Looks like I will be having a little fun on the lake this summer ;-)
 

xjgary

Member
Joined
Sep 25, 2018
Messages
5
Location
Carpinteria
I am liking those HP numbers and the 8,500 rpm is getting closer.There are things we can do to engines to make HP at lower rpms.I was looking foreward to beating a sled like a red headed step child for a bit until I needed the engine.Looks like I will be having a little fun on the lake this summer ;-)
 

xjgary

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Joined
Sep 25, 2018
Messages
5
Location
Carpinteria
You guys need to join the Yamaha Engines for aviation facebook site. There are many reasons why a yammy jetski or Motorcycle engine won't work in an airplane. Search that site and you will find answers. And there is much more to a PSRU than simple gear reduction. One is that it serves as a Heavy Duty fifth bearing to overcome the gyroscopic forces of the propeller during turns. Look at any real aircraft engine and the front crank bearing is huge! Another is vibration dampening.
 

wsimpso1

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Messages
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Saline Michigan
There is a chain drive in that torque converter on snowmobiles.What I am saying is we may be able to eliminate the need to buy your $3,500 psru and save even more money or eliminate running 2 gear drive reduction units on an emgine for less mechanical drag and more reliability.
As an engineer with 23 years doing transmission design engineering, I suspect you are greatly underestimating the series of jobs in design, fabrication, and proveout of power transfer equipment suitable to man rated airplane propulsion.

Further, I also think that many folks are overestimating the losses in PSRU. I see frequent mention of large losses in systems while many references talk in terms of 1% losses per gear mesh set. My history in automatic transmissions, most recently with four planetaries, a transfer gear set, a final gear reduction, and half of the several multiplate wet clutches open typically are 97% efficient when the torque converter clutch is engaged. Gear sets and bearings, when warmed up, are very efficient things. When I see a show with a big difference between engine and wheel horsepower, I often wonder how many minutes they ran under power to bring the tranny and final drive up to temperature. Usually a few seconds at a time, which might be representative of the drag strip, but certainly not of our typical start, warmup and taxi at 8-10% power, runup check at +50% power, taxi some more, then take off. I would bet our PSRU get to temperature and low losses.

The high concern over efficiencies and low estimation of what it takes to make a light, sturdy, reliable drive both lead me to predict a steep learning curve ahead. A $3500 PSRU that works well is likely a major bargain compared to rolling your own machine. As a hobby, proceeding with your own scheme should prove interestiing, but i urge a thorough set of proveout runs over the range of rpm and torque available. Running with several Eiffel clubs and/or suitable props will be needed. Understand that a decent proveout usually requires multiple sets of hardware.

Even the application of established engine, PSRU, and prop are frequently not plug and play...

If you proceed with the project, good luck and we look forward to reports on the progress.

Billski
 

Ally Wilke

Well-Known Member
Joined
Jan 19, 2021
Messages
51
As an engineer with 23 years doing transmission design engineering, I suspect you are greatly underestimating the series of jobs in design, fabrication, and proveout of power transfer equipment suitable to man rated airplane propulsion.

Further, I also think that many folks are overestimating the losses in PSRU. I see frequent mention of large losses in systems while many references talk in terms of 1% losses per gear mesh set. My history in automatic transmissions, most recently with four planetaries, a transfer gear set, a final gear reduction, and half of the several multiplate wet clutches open typically are 97% efficient when the torque converter clutch is engaged. Gear sets and bearings, when warmed up, are very efficient things. When I see a show with a big difference between engine and wheel horsepower, I often wonder how many minutes they ran under power to bring the tranny and final drive up to temperature. Usually a few seconds at a time, which might be representative of the drag strip, but certainly not of our typical start, warmup and taxi at 8-10% power, runup check at +50% power, taxi some more, then take off. I would bet our PSRU get to temperature and low losses.

The high concern over efficiencies and low estimation of what it takes to make a light, sturdy, reliable drive both lead me to predict a steep learning curve ahead. A $3500 PSRU that works well is likely a major bargain compared to rolling your own machine. As a hobby, proceeding with your own scheme should prove interestiing, but i urge a thorough set of proveout runs over the range of rpm and torque available. Running with several Eiffel clubs and/or suitable props will be needed. Understand that a decent proveout usually requires multiple sets of hardware.

Even the application of established engine, PSRU, and prop are frequently not plug and play...

If you proceed with the project, good luck and we look forward to reports on the progress.

Billski
I removed one drive axel from my semi truck.I gained .5 mpg.4 grand in fuel savings a year is a lot of drag gone.
 

GTX_Engines

Active Member
Joined
May 17, 2013
Messages
42
Location
Columbia, SC
Yes, the built in rubber damper is not adequate to eliminate destructive torsional vibration. Three solutions available are the RK-400 centrifigal clutch, Skytrax uses a sprag clutch in the gearbox and some have been successful using a rubber guibo with the 4 cylinder RX-1 and props that have a low moment of inertia(light wood props).

I should add that these engines will not even idle well or accelerate without a clutch due to vibration.
The engine idles smooth w/o a clutch. It accelerates the same with or without a clutch. A clutch is used only to make initialy start-up smooth, or in the case of a centrifugal clutch to allow the engine to idle w/o prop thrust on the water. W/o a clutch, as you turn on the key you need to get a feel for opening the throttle in synch with revving the motor through the initial turns to get it to about about 1500 RPMS, then you can throttle back to normal idle just fine.

When i started doing this in 2010-2011 we all thought a clutch was necessary, but it turned out that if you build in the intake and exhaust correctly (using the stock intake plenum, and stock length for the headers, e.g., ) and after 2015 and extensive testing I started making and selling YG4 and YG4i power plants abd conversion kits without clutches - which my customers loved, since it eliminated the single-point-of-failure that is the clutch.

The internal rubber damper is thought to be sufficient for damping torsional vibration when a prop is hard coupled to the PTO countershaft through a conventional gearbox such as the AK7 Mohawk sells, Rotax C, and the Hy-Vo chain Mohawk "Silent Drive" - all of which have been extensively tested and flown for many years with no soft start clutch. But I still use a BMW flex shaft coupler with M10x 78mm on-center steel sleeved holes. You can't use the Rotax donut, it will shred in under ten hours of normal flying.

If anyone is considering re-gearing the countershaft internally, it simply cannot be done within the confines of the stock block, and any changes to the casting will significantly compromise the integrity of the crankcase leading to imminent and catastrophic failure. You would have to start from scratch and make your own block. It aint' worth it.

Skytrax "All-In-One" with sprag clutch is $3500.00, Mohawk Aero adapter with conventional gearbox (there are several choices) costs $2995.00 and comes with either an RK400 clutch (especially desired by float planes and air boat guys) or a PTO flange coupling with a BMW heavy-duty rubber flex shaft coupling (a much beefier "rubber donut"). Gearbox can be mounted upright, or down.

Someone once built a successful belt drive Apex on a FW tractor before the options that are available today were on the market. It is actually the first successful Apex, but it was never replicated after i started making gearbox adapters for the Apex, as it is impractical. Matter-of-fact, he provided Steve Henry with the first wiring info to successfully run the Apex, and Steve gave that info to me in 2017, then to others starting around early 2019. That was a one-off that no one to my knowledge has ever done since. These days a belt-drive PSRU on a YG4 makes about much sense as sticking a Ferrari engine in a VW bus. It is heavy, it creates a lot of harmonic vibration, and belts wear out quickly. Most belt systems are only good for about 6800 RPM, hence they work well on say a Subaru or a 351 c.i. Ford airboat, but not so great for a Yamaha Genesis 4-cylinder aircraft. Or a 3 cylinder, though this has been several times with limited success by individual builders (none for repeat general sales). Both the YG3 and the YG4 turn the same relative PTO shaft speeds, up to 8700 RPMs+, well beyond reasonable cog belt speeds.

If you desire to re-invent the wheel, be aware that it will cost you a ton of money more than either Skytrax or Mohawk, and set you back at least another year - and that's if you already know what you are doing, have excellent CAD skills and software, and know where to get gears, hobs, castings, CNC work, raw materials, all the hardware bits and pieces...then there's the testing.

If anyone is curious to see the Silent Drive, go to: Mohawk Aero Silent Drive Video,

and also this one: Silent Drive Flight Demo

it has about 50 hours on it, no soft-start clutch, and does have a prop-strike protection "slipper" (break-away) clutch integral to the new 49-tooth Arctic Cat sled top gear. That part only cost me $400, whereas the same **** thing from Rotax in their 912 series gearbox is $1200. That is exactly the same slipper clutch Bambardier uses on their Ski Doos, folks. Why do they charge 3x as much as they are actually worth? Because it is Rotax, that's all.

Talk to ya later, have a good day. Time to get out to the shop and finish cutting the keyway for the sprag clutch drum that's on the mill for a YG2 customer.
 
Last edited:

Ally Wilke

Well-Known Member
Joined
Jan 19, 2021
Messages
51
The engine idles smooth w/o a clutch. It accelerates the same with or without a clutch. A clutch is used only to make initialy start-up smooth, or in the case of a centrifugal clutch to allow the engine to idle w/o prop thrust on the water. W/o a clutch, as you turn on the key you need to get a feel for opening the throttle in synch with revving the motor through the initial turns to get it to about about 1500 RPMS, then you can throttle back to normal idle just fine.

When i started doing this in 2010-2011 we all thought a clutch was necessary, but it turned out that if you build in the intake and exhaust correctly (using the stock intake plenum, and stock length for the headers, e.g., ) and after 2015 and extensive testing I started making and selling YG4 and YG4i power plants abd conversion kits without clutches - which my customers loved, since it eliminated the single-point-of-failure that is the clutch.

The internal rubber damper is thought to be sufficient for damping torsional vibration when a prop is hard coupled to the PTO countershaft through a conventional gearbox such as the AK7 Mohawk sells, Rotax C, and the Hy-Vo chain Mohawk "Silent Drive" - all of which have been extensively tested and flown for many years with no soft start clutch. But I still use a BMW flex shaft coupler with M10x 78mm on-center steel sleeved holes. You can't use the Rotax donut, it will shred in under ten hours of normal flying.

If anyone is considering re-gearing the countershaft internally, it simply cannot be done within the confines of the stock block, and any changes to the casting will significantly compromise the integrity of the crankcase leading to imminent and catastrophic failure. You would have to start from scratch and make your own block. It aint' worth it.

Skytrax "All-In-One" with sprag clutch is $3500.00, Mohawk Aero adapter with conventional gearbox (there are several choices) costs $2995.00 and comes with either an RK400 clutch (especially desired by float planes and air boat guys) or a PTO flange coupling with a BMW heavy-duty rubber flex shaft coupling (a much beefier "rubber donut"). Gearbox can be mounted upright, or down.

Someone once built a successful belt drive Apex on a FW tractor before the options that are available today were on the market. It is actually the first successful Apex, but it was never replicated after i started making gearbox adapters for the Apex, as it is impractical. Matter-of-fact, he provided Steve Henry with the first wiring info to successfully run the Apex, and Steve gave that info to me in 2017, then to others starting around early 2019. That was a one-off that no one to my knowledge has ever done since. These days a belt-drive PSRU on a YG4 makes about much sense as sticking a Ferrari engine in a VW bus. It is heavy, it creates a lot of harmonic vibration, and belts wear out quickly. Most belt systems are only good for about 6800 RPM, hence they work well on say a Subaru or a 351 c.i. Ford airboat, but not so great for a Yamaha Genesis 4-cylinder aircraft. Or a 3 cylinder, though this has been several times with limited success by individual builders (none for repeat general sales). Both the YG3 and the YG4 turn the same relative PTO shaft speeds, up to 8700 RPMs+, well beyond reasonable cog belt speeds.

If you desire to re-invent the wheel, be aware that it will cost you a ton of money more than either Skytrax or Mohawk, and set you back at least another year - and that's if you already know what you are doing, have excellent CAD skills and software, and know where to get gears, hobs, castings, CNC work, raw materials, all the hardware bits and pieces...then there's the testing.

If anyone is curious to see the Silent Drive, go to: Mohawk Aero Silent Drive Video,

and also this one: Silent Drive Flight Demo

it has about 50 hours on it, no soft-start clutch, and does have a prop-strike protection "slipper" (break-away) clutch integral to the new 49-tooth Arctic Cat sled top gear. That part only cost me $400, whereas the same **** thing from Rotax in their 912 series gearbox is $1200. That is exactly the same slipper clutch Bambardier uses on their Ski Doos, folks. Why do they charge 3x as much as they are actually worth? Because it is Rotax, that's all.

Talk to ya later, have a good day. Time to get out to the shop and finish cutting the keyway for the sprag clutch drum that's on the mill for a YG2 customer.
There are companies that already make the internal gears for these engines as after market performance parts.Aftwr talking to people who know these engines and studying every imagebof them that I can get my hands on.There is not enough room.One of the best stories in Super Bike racing was about a man who cast his own engine blocks and beat the big companies on the track out of his shop.We can do better than what we have for engines.The engine is what has been the problem since long befor the Wright bros.An engine costing as much as my plane build can take a flying leap.An engine tht is not in the ball park of 1to1 HO to weight ratio can fly a kite too.I believe the engine is the part holding back home builders and I believe we can change that even if I have to do it alone.Thank you for your input.People responding to this post help me learn.I love it!
 

Ally Wilke

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Joined
Jan 19, 2021
Messages
51
I am a long haul trucker.I own my own semi and lease to an all owner operator carrier.I love my freedom to be incontrol of when where and how I work.I booked a load Friday picking up at a Briggs and Stratton plant.I think I am going to show up a bit early and knock on some engineer doors and explain the home builders engine problems to some people.The lawn mower people you ask?How fast is that metal blade spinning and pulling on that thrust bearing😆
 

Ally Wilke

Well-Known Member
Joined
Jan 19, 2021
Messages
51
The engine idles smooth w/o a clutch. It accelerates the same with or without a clutch. A clutch is used only to make initialy start-up smooth, or in the case of a centrifugal clutch to allow the engine to idle w/o prop thrust on the water. W/o a clutch, as you turn on the key you need to get a feel for opening the throttle in synch with revving the motor through the initial turns to get it to about about 1500 RPMS, then you can throttle back to normal idle just fine.

When i started doing this in 2010-2011 we all thought a clutch was necessary, but it turned out that if you build in the intake and exhaust correctly (using the stock intake plenum, and stock length for the headers, e.g., ) and after 2015 and extensive testing I started making and selling YG4 and YG4i power plants abd conversion kits without clutches - which my customers loved, since it eliminated the single-point-of-failure that is the clutch.

The internal rubber damper is thought to be sufficient for damping torsional vibration when a prop is hard coupled to the PTO countershaft through a conventional gearbox such as the AK7 Mohawk sells, Rotax C, and the Hy-Vo chain Mohawk "Silent Drive" - all of which have been extensively tested and flown for many years with no soft start clutch. But I still use a BMW flex shaft coupler with M10x 78mm on-center steel sleeved holes. You can't use the Rotax donut, it will shred in under ten hours of normal flying.

If anyone is considering re-gearing the countershaft internally, it simply cannot be done within the confines of the stock block, and any changes to the casting will significantly compromise the integrity of the crankcase leading to imminent and catastrophic failure. You would have to start from scratch and make your own block. It aint' worth it.

Skytrax "All-In-One" with sprag clutch is $3500.00, Mohawk Aero adapter with conventional gearbox (there are several choices) costs $2995.00 and comes with either an RK400 clutch (especially desired by float planes and air boat guys) or a PTO flange coupling with a BMW heavy-duty rubber flex shaft coupling (a much beefier "rubber donut"). Gearbox can be mounted upright, or down.

Someone once built a successful belt drive Apex on a FW tractor before the options that are available today were on the market. It is actually the first successful Apex, but it was never replicated after i started making gearbox adapters for the Apex, as it is impractical. Matter-of-fact, he provided Steve Henry with the first wiring info to successfully run the Apex, and Steve gave that info to me in 2017, then to others starting around early 2019. That was a one-off that no one to my knowledge has ever done since. These days a belt-drive PSRU on a YG4 makes about much sense as sticking a Ferrari engine in a VW bus. It is heavy, it creates a lot of harmonic vibration, and belts wear out quickly. Most belt systems are only good for about 6800 RPM, hence they work well on say a Subaru or a 351 c.i. Ford airboat, but not so great for a Yamaha Genesis 4-cylinder aircraft. Or a 3 cylinder, though this has been several times with limited success by individual builders (none for repeat general sales). Both the YG3 and the YG4 turn the same relative PTO shaft speeds, up to 8700 RPMs+, well beyond reasonable cog belt speeds.

If you desire to re-invent the wheel, be aware that it will cost you a ton of money more than either Skytrax or Mohawk, and set you back at least another year - and that's if you already know what you are doing, have excellent CAD skills and software, and know where to get gears, hobs, castings, CNC work, raw materials, all the hardware bits and pieces...then there's the testing.

If anyone is curious to see the Silent Drive, go to: Mohawk Aero Silent Drive Video,

and also this one: Silent Drive Flight Demo

it has about 50 hours on it, no soft-start clutch, and does have a prop-strike protection "slipper" (break-away) clutch integral to the new 49-tooth Arctic Cat sled top gear. That part only cost me $400, whereas the same **** thing from Rotax in their 912 series gearbox is $1200. That is exactly the same slipper clutch Bambardier uses on their Ski Doos, folks. Why do they charge 3x as much as they are actually worth? Because it is Rotax, that's all.

Talk to ya later, have a good day. Time to get out to the shop and finish cutting the keyway for the sprag clutch drum that's on the mill for a YG2 customer.
Yup.We are getting hosed from all angles.They feed us old tech as new and charge is premium prices while brainwashing us that we have the newest and best.My delivery truck in 1900 would have been electric.125 years later Telsa is all the rage lols.Keep doing what you do.You are the people thay change the world.
 

Marc Bourget

Well-Known Member
Joined
Feb 28, 2011
Messages
379
Location
Stockton, California
I am a long haul trucker.I own my own semi and lease to an all owner operator carrier.I love my freedom to be incontrol of when where and how I work.I booked a load Friday picking up at a Briggs and Stratton plant.I think I am going to show up a bit early and knock on some engineer doors and explain the home builders engine problems to some people.The lawn mower people you ask?How fast is that metal blade spinning and pulling on that thrust bearing😆
Diameter of a lawnmower blade is less than optimum. Get to a larger diameter then you have gyroscopic forces that lawnmower engineers do not have to deal with.
 

TFF

Well-Known Member
Joined
Apr 28, 2010
Messages
14,518
Location
Memphis, TN
You are thinking about problems, which is good. Throwing every idea out there at something, does not work. Of the thousands out there, only a small number really apply.
The idea of internal gear change is worthy to consider, but the evidence says no; time for next idea. Do you drive a five speed rig or a nineteen, or something in between? I doubt it’s five and you are not going to give up the performance of the other gears. That is what you are asking for with your proposal. I know three CDL people who drove while getting their helicopter pilots licenses. One was stuck delivering pipe in Denver with a five speed being low in seniority. He said that sucked.

$3500 for an off the shelf gearbox is cheap. Not free, but cheap. If you did all the work yourself and billed it for just one, it would be $25-50k. Why? Well you didn’t make money making anything else for other people. Got to pay yourself, and can’t spread it out piggy backing on other setups. Space and machinery payments with utilities is costing, and high grade materials are very expensive. Then the design has to be good. Paying yourself for that just like you would pay someone else. You don’t deliver for free do you? You got to pay for stuff and you to make it worth it, right? At $3500, profit is only going to be a couple of hundred dollars all said and done with a huge liability hanging over your head. Everything in that box is custom. Those gears are not off the shelf turned out in the thousands. They are one at a time. Casting a case, one at a time. And no there are not thousands with money to buy at $500, just lots of dreamers. If it got to $50, they would still say too expensive. The non dreamers will work a little harder to make an extra $3500 to get what they want.

There is a local that casts top fuel drag blocks behind his trailer house. He is kind of a legend. He doesn’t ask if someone else can solve his problems. I would love to do something like that, but I would have to give up my life as is, make a sharp 180 and forget family and friends to make it happen, or something like that. That is why $3500 is cheap. If you have the tools and knowledge right now, start whittling it out. If you don’t, it will take ten years to work your way through how to do it.
You haven’t even built the plane yet.
 

Ally Wilke

Well-Known Member
Joined
Jan 19, 2021
Messages
51
Good stuff I love it.For me the engine is the hard part.I am confident I can build a plane of my choice from plans.The Model A of experimental engines I beleive would make more dreams come true for people wanting to fly.My Freight Shaker is a 10 speed although I wosh it was a 13 speed.The jump from 9 to 10th is to big.When it is time for a rebuild I will swap it out to a 13.
 
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