Alternate engine expierences and builds

[scottessex]

That was another thing I was thinking, What is a realistic expected cost?
Most gearboxes belt reduction units etc sell for around 2k to $2500.
Then factor in the cost of the engine, exhaust, and all the parts needed to hook it up,
I think that the $5 to $10k is a very realistic number.
yes you can get away cheaper, but realistically, If I were to buy engines, supply a gearbox and parts for the entire pkg, I am sure it would be closer to the $10k.
Jan Eggenfelners new Honda 100hp engine pkg and gearbox is right under $10k.
What is a new rotax 582 these days? I would bet closer to 10 than 5.
Most of us gyro guys are cheap...er thrifty.
Even a Harley engine and tranny ain't going to be cheap if you are building custom motorcycles, and there are a whole lot more people buying them, than aircraft engines.

 

[Jason O]

Torque at the prop

Torque at the prop

Opsled

The torque I quoted is at the prop, so it is mutliplied by 3.47, the propeller RPM is engine RPM divided by 3.47

Jason

I have a dyno sheet for the 120 Yamaha Vector engine from Dynotech.
I wish I could upload it for you but when I try it says the file is to large for this forum. Dynotech must measure differently than what you have on the engines you decribe as they don't have TQ numbers as high.

Here is the HP and TQ highs.

It has max HP being at 8600rpm with 118.8 CHp and 72.5 Clb-ft of torque.

Max torque is at 6900rpms with 106.2 CHp and 80.8 Clb-ft of torque.

What's really interesting is that even down at 5000rpm it has 74.1 Clb-ft of torque which is still more than where it makes max HP. It shows these engines like to pull and pull hard. This makes me wonder if you need all that RPM or would you be better off lowering it down into the max torque range and giving it more work with the prop????

opsled

 

[Jason O]

least expensive options

least expensive options

Scott,

Unless you have the capabilities to manufacture intakes and rebuild carbs and/or make junk yard electronics work, I believe the best way to go for economy is use all the stock parts and electronics from the engine. When I built the BMW, the parts were fairly reasonable, but after I purchased the two aftermarket ignition modules, two coils, Voltage regulator, alternator the price started to creep on me. If you are going to go rock bottom on price, I believe you should find an engine that has the horsepower you want in its stock form and then try to get all parts from the doner vehicle. The Yamaha is bone stock except for the exhaust and I removed the intake airbox and put filters on each carb. After the redrive, my next most expensive item is the exhaust. I went cheap on the first exhaust system on the BMW and it lasted all of 10 hours. In the Yamaha, I went all out and had a custom exhaust and muffler made from 304 stainless and I expect it to outlast the engine.

Jason

That was another thing I was thinking, What is a realistic expected cost?
Most gearboxes belt reduction units etc sell for around 2k to $2500.
Then factor in the cost of the engine, exhaust, and all the parts needed to hook it up,
I think that the $5 to $10k is a very realistic number.
yes you can get away cheaper, but realistically, If I were to buy engines, supply a gearbox and parts for the entire pkg, I am sure it would be closer to the $10k.
Jan Eggenfelners new Honda 100hp engine pkg and gearbox is right under $10k.
What is a new rotax 582 these days? I would bet closer to 10 than 5.
Most of us gyro guys are cheap...er thrifty.
Even a Harley engine and tranny ain't going to be cheap if you are building custom motorcycles, and there are a whole lot more people buying them, than aircraft engines.

 

[opsled]

Phil, just be careful not to get caught in that "torque is what matters" misconception. Thrust comes from horsepower, and 74.1 lb/ft at 5,000 RPM is only 70.5 HP. Put a 2:1 reduction drive on it, and performance-wise you'd essentially have a much heavier 582 that burned less fuel.

I have been told this before but never with an explination as to why?

I know there is a relationship between HP and TQ but not all powerplants are the same when it comes to the numbers they are capable of producing. Torque must be relevant or why even measure it. I build big trucks for a living and torque is what matters there. Drivetrain components are rated by torque right in their model numbers. Pulling a load is work and I assume turning a prop is aswell. A 500hp big block Chevy engine wouldn't even come close to being able to do the same work as a 500hp Cat diesel. The Chevy would have torque numbers at what 450? maybe? The Cat diesel is in the 1200 to 1400 range or higher. In the majority of senarios I deal with when it comes to doing sustained hard work the engine with the highest torque numbers will outperform HP all day and live to do it again tomorrow. The applications I see where HP is king are when the work is light but must be done quickly (racing and such). I don't fly but do love my 2 strokes. To me they are more like a race engine. They are quick, have a narrow powerband and don't last long when given sustained hard work. I would think grinding a prop would be hard work. This work needs to be sustained and I would assume the ability to vary throttle without losing power would be nessessary. I would think an engine who's powerband is broad with strong torque numbers in a flat curve would be just the ticket.

Not trying to argue just trying to get my head around what you are saying. I know these are apples and oranges but my experiance tells me that most mechanical principals apply consistantly, no matter the application.

opsled

 

[Not Yet]

Horsepower


T = Torque
N = Revolutions per Minute
P = Horsepower
C = 5252​

P = T N / C

T = P C / N

N = P C / T

100 HP at 5,000 RPM requires 105 ft lbs of torque
100 HP at 8,000 RPM requires 66 ft lbs of torque


As you can see, you can trade some torque for RPM and still have the same horse power.
In other words if you have 2 engine with the same horse power, the engine that has more torque will get its horsepower at a lower RPM, however work is done by horsepower.

 

[GyroRon]

Or put another way.....

The 500 HP big block chevy ( which would realistically make about 500+ lbs of torque ) might make that 500 HP at around 6000 rpms.

The 500 HP cummins in a big rig ( with 1200-1400 lbs of torque ) makes it's 500 HP at only 2000 rpms.

If you were able to rev the cummins to 6000 rpms, it would make well over 1500 hp...

 

[GyroRon]

And as for the alternative engine talk and talk of Yamaha, right now the gremlin is in the clutch drive between the engine and the gearbox. So far everyone who is flying these engines has had some kind of issue of one sort or another with their clutch. If we could get this issue worked out, I can't see why these engines won't go at the least a few hundred hours.... Jason, I would sure like to talk to you about your clutch again, gimme a ring

 

[PW_Plack]

...Torque must be relevant or why even measure it...

Torque is simply a measurement of a twisting force. Suppose the Chevy big-block makes 500 lb-ft of torque - I'll create that same amount of torque standing on the end of a 30-inch breaker bar trying to loosen a nut. (I weigh about 200 lb.) The Chevy can do more work because it can make that torque at 4,500 RPM...and torque at speed is horsepower.

Torque matters in a vehicle which couples power to wheels, because to get it moving, you need lots of twisting force at low RPM, even through a variable transmission. A propeller doesn't start to put significant load on an engine until it gets near its max operating RPM, so low-end torque is meaningless (except for turning accessories, prerotator, etc.)

Also, comparing two engines rated for a peak output of 500 HP is not the same as comparing two engines both making 500 HP. Put the 500 HP Chevy through a 3:1 reduction drive which lets it make its 500 HP at 6,000 RPM, and the output shaft will make the same torque as the Cat doing 500 HP at 2,000 RPM.

Measuring torque is also a requirement for measuring shaft horsepower. For example, a chassis dyno used to measure the rear-wheel horsepower of a car needs both the rate of acceleration (torque) and the speed of the drum (RPM) to calculate horsepower.

 

[Friendly]

And as for the alternative engine talk and talk of Yamaha, right now the gremlin is in the clutch drive between the engine and the gearbox. So far everyone who is flying these engines has had some kind of issue of one sort or another with their clutch. If we could get this issue worked out, I can't see why these engines won't go at the least a few hundred hours.... Jason, I would sure like to talk to you about your clutch again, gimme a ring

Why use the clutch at all if it is a source of problems? What problems are there with the direct drive?

 

[Passin' Thru]

Why use the clutch at all if it is a source of problems? What problems are there with the direct drive?

I had wondered why not just use the rubber coupling? There's probably a reason, I just don't know it.:noidea:

 

[GyroRon]

For whatever reason, when you start the engine with a rubber coupler instead of a clutch, the engine shakes and vibrates wildly. And in the case of my own engine, it would not accellerate to a higher rpm to get past the vibration. Think of a rotax 2 stroke started and idled at 1000 rpms.... Same kind of thing, except the yamaha for me anyway, it would start and idle but thats it, give it more throttle and it would just vibrate more.

With the clutch, it takes the load off the engine from the prop and it can start at the normal designed no load rpm. Once running you give it throttle and it increases rpms and at the normal rpms it would be loaded in a snowmobile, the clutch engages and the prop turns. It's is seemless and works great.

The rubber coupler might would work if there was a change to the carbs to allow it to be able to start cold with the idle at 2000+ rpms. But mine wouldn't start except at idle, and neither did Racers.

The problem we are facing with the clutch, is three fold....

One area of concern is the clutch were using is mostly a RK-400 clutch made for rotax engines. But the drivebody part of the clutch ( the part that fits on the engines crankshaft and holds the clutch shoes ) has to be special made just for the yamaha. This drivebody has been a problem.... The RK400 drivebody is made of hardened and coated steel, and the drivebodys Todd has had made so far were made out of highgrade steel but not hardened or coated. We are learning now that without the hardening, the clutch shoes are putting accellerated wear and tear on the drivebodys arms that push the clutch shoes. The clutches retention springs are also eating into the drivebody, rapidly wearing out that area. And icing on the cake.... Todd had all of the drivebodys ( except mine which he hand made on his mill ) built by a outside contractor ( a person who posts here and is in the business of making aircraft parts and kits, so you would expect perfection right.....? ) And now he has learned that the drivebodys he had made are all flawed and were made out of round. So once installed on a engine, the entire drivebody will have several thousands of runout. Todd is now in the process of trying to get new drivebodys made, and made right, and then sent off for a hardening treatment.... hopefully this will fix this part of the clutch problems.


The next problem is the clutch shoes have a pair of springs that pull the shoes inwards, so that at low rpms it will disengage. Well all of us flying these clutches in our yamahas have experienced a busted spring. The springs have all broke where the two ends of the spring meet and hook to each other. I have friend who is running a RK-400 clutch on his Rotax 670, and he has had simular problems too, so this may be a issue with the clutch shoes / springs themselves instead of a yamaha problem. But eitherway it is a problem.

I am on my second set of shoes / springs. The first set lasted about 65 hours before any problems, when at about 65 hours the inside lip on the inside of the shoes ( the side of the shoes that rides on the non hardened drivebody ) broke off on 2 of the 4 shoes. without the inside lip, it was simular to a broken spring and the clutch still functioned but it would not disenage fully at idle. I flew it this way for another 20 hours before installing new shoes. The new shoes lasted about 40 minutes total before the spring broke....

The last issue is making sure the gearbox is centered over the engines crankshaft. On a Rotax engine, the crankcase has a boss on the end of the crankcase that the gearbox fits tight on and this automatically centers the gearbox. When Todd designed his conversion package, centering the gearbox was overlooked. It was assumed the bolts alone would center the box. But the bolts don't.... the bolts, even with precisely located and drilled and tapped holes, get it close to centered, but there is still some movement of the gearbox side to side and up and down and unless you luck out, you could tighten all the bolts up and have the gearbox to be off center by several thousands of a inch. Once we figured this out, Todd made a new provision on his back plate the gearbox mounts to that replicates the boss on the rotax crankcase to insure the gearbox is centered. I had to retro fit this provision, and hopefully it did center my gearbox. I have a feeling though that due to my dumb luck, my box was originally installed perfectly centered, and now with the provision I think I may be off center, as I am seeing rapid wear of the clutch drivebody in the last 25 hours, wear that was not there at all before installing the centering provision.


In the end, this clutch has been the sore point of this conversion. We have worked out the jetting issues.... the fuel delivery issues.... and all other bugs. Now we have to get the clutch to last us at least 200-300 hours minimum and we can call this conversion a success.

Here is what the RK-400 drivebody looks like https://www.air-techinc.com/prod_cat_item.asp?categoryID=atclutch&typ=Exclusives&ID=3046


And here is what the shoes look like https://www.air-techinc.com/prod_cat_item.asp?categoryID=atclutch&typ=Exclusives&ID=3048

 

[Jason O]

Yamaha 120 Update

Yamaha 120 Update

Hello All,

So far this flying season I have put about 33 hours on the yamaha and it continues to run strong. The total hours on the engine is now about 70, so I can say one thing for sure, it will run for 70 hours fairly trouble free, anything else is pure speculation.

Regards
Jason

 

[All_In]

So far I think we can agree it's a success! You guys will figure out the clutch problems.

 

[HobbyCAD]

Hi There Ron,

This drivebody has been a problem....not hardened or coated.

On another application of a near identical clutch, where this wear is not so apparent, the drivebody manufacturing instruction says "Harden part through to 35 - 40 Rockwell C Scale, after machining. Electolysis HARD Nickel Plate per MIL-C-26074 Class 2, 0.0005 to 0.001 Dychromate Seal.

The springs have all broke where the two ends of the spring meet and hook to each other.

Does your shoes have the spring retaining indents on them, prohibiting the spring from protruding out? I'm wondering why you are getting wear on the drivebody, from the spring touching it?

Is it simply the springs coming undone, or are the tangs on the end breaking off?

Unfortunate to hear you are having problems with that machining contractor. Seems you are not alone.

 

[Friendly]

Ron,
That is a very good write up on the progress. As little hours as are these engines, they are still evolving into the finished product. It is good that you guys believe in your product. It helps over come frustration. I hope I persevere was well with the Weber when I start. I also hope I can give a good candid report as you have done.
Thanks
Jason,
I think your results are important, however, we all know that gyros harder on engines than fixed wing. Are you running a clutch?

 

[GyroRon]

Hi There Ron,



On another application of a near identical clutch, where this wear is not so apparent, the drivebody manufacturing instruction says "Harden part through to 35 - 40 Rockwell C Scale, after machining. Electolysis HARD Nickel Plate per MIL-C-26074 Class 2, 0.0005 to 0.001 Dychromate Seal.



Does your shoes have the spring retaining indents on them, prohibiting the spring from protruding out? I'm wondering why you are getting wear on the drivebody, from the spring touching it?

Is it simply the springs coming undone, or are the tangs on the end breaking off?

Unfortunate to hear you are having problems with that machining contractor. Seems you are not alone.

If you google search RK400 clutch, that is what my clutch is. The only difference is the drive body has to be custom made to fit the yamaha engine, the RK400 drivebody can not be used on the yamaha engine. Mine was made by hand, by Racer. It is made out of steel, not sure the grade, but was not hardened or coated with anything. The wear is on the drivebodys arms that push on the shoes. The shoes are wearing into these arms, eating away at the metal. As for the shoes breaking and the springs, I have no idea. My only guess is there may be too much of a gap between the drivebody the clutch and the outter cover, allowing for the clutch pack to move around too much and cause excessive wear. Were working on it though....

 

[HobbyCAD]

Hi There Ron,

Must sure be some force on the shoes there, to eat into the drivebody pillars. Does yours not have the fibreglass sheet wearpads on the load bearing sides of the shoes, to prevent exactly this metal to metal wear taking place? In the picture, you can see the greenish sides on my clutch shoes, they are the fibreglass wearpads. Correct sized fibreglass wearpads will also ensure a snug fit, allowing only centifugal movement, no radial play. Looking at the Air-Tech Inc website, the RK-400 shoes in the picture attached seem to not have any wearpads on the ends. Now that's a sure problem, the metal to metal contact, in a high vibration area.

Your clutch lining thickness should take care of the shoes not needing to "fly" out very far, thus straining the spring too much.

How about the 2 little "keepers" on the shoes, to stop the spring from popping out. In total, these should be 8 of those keeping the whole spring in. Again, looking at the website, the picture of the 4 shoes do not show the well defined punchmarks into the shoe, that produces the good spring retainer lips. The only hassle with my spring retainers, you STRUGGLE to assemble the 4 shoes together !!

 

[GyroRon]

Looks like your shoes are just like my shoes. But different. Where are you getting those shoes? That would solve both of my problems.

 

[Lee Scatt]

BMW R1100 rt

BMW R1100 rt

I just aquired a 1998 engine from subject motorcycle. It has 27,000 miles on the clock. It is rated 90 hp@7250, 70 ft/lb@ 5500, 10.7/1, 4 valve/cyl.
I am planning on using a Suzuki SPG-4 PSRU at 2.5/1, with clutch and rubber damper.
I will spin a 68 inch,3-bladed IVO initially, and possibly a 72 inch,2-blade Warp Drive down the road.
I am going to try and figure out the wiring, the stock harness is a nightmare. I think I can seperate the required connectors and get the motronic ECU to operate. I have seen an ECU modification that allows the use of a wide-band O2 sensor, and allows fuel mapping adjustments. I hope to get it to run closed loop at cruise power setting.
I have a Walbro in-line fuel pump that delivers 45 psi at 5.5 amps.
I am using the stock header, which is 2 into 1 at a 2 inch outlet. I will try and find a carbon fiber muffler for it.
I am estimating the engine wt. to be about 185 lbs. with all required appurtenances, less the prop.
I am waiting on a wiring diagram right now, to help with the mods.
I have attempted this once before, with an R100 airhead. I had too low of a PSRU ratio and couldn't spin my small prop fast enough without over heating the heads. I sold it to a fellow in Alaska.
I hope to have better luck this time, I think the oil-head engine might have better cooling if set up properly.
I am open to suggestions, I need all the help I can get.
I am also scrounging parts. I need a control stick assy, rotorhead, seat tank, asi, rod-ends, hardware, etc. Anything you have on the shelf you want to get rid of, drop me a note, I can put it to use.
I will start taking pics soon, when the assembly begins.

 

[Friendly]

Looks like your shoes are just like my shoes. But different. Where are you getting those shoes? That would solve both of my problems.

It looks like you have a very simple fix to your problem Ron.