o-360-j2a downrating

[slick1537]

My instructor said that this engine in the Beta II is at 180 horse power but is down rated to 145 horse power. He said this was done to add to altitude ceiling and increase the time to be overhauled. However how exactly is an engine de-rated? Wouldn't it be through a gear system that adds more torque at the same time, and if this is the case, wouldn't the system no long be direct drive?

[Gerhardt]

The derating isn't done via gearing, but by reducing the acceptable operating range of the engine.

[Goldy]

If I asked you to run 100 laps and maintain 4 minute miles, you would be pretty tired. But if I asked you to walk the same 100 laps, you would still be rested at the end....there. I just de-rated you. Same goal accomplished, less wear and tear, you and the Lycoming engine can last longer.

 

One of the many very smart things that Frank does to his ships.

 

Goldy

Edited August 10, 2007 by Goldy

[james28]

is it not just a governor that limits the engine rpms?

[Goldy]

is it not just a governor that limits the engine rpms?

 

 

James- not really. If you loaded an R22 full of bricks, pulled full collective, the engine at sea level would give you the 180HP it can pump out. The drive train would then fall apart and you would fall out of the sky..but thats another topic.

 

Really, what limits the HP of the engine is you. You determine how much MP you are going to pull in any given situation. The real advantage is this. ...lets say the drivetrain can take 131 hp continuous and about 145 hp for short times. ( Just a rumor...not actual figures!). By putting in an 180 hp engine, when you are flying at 5000 feet altitude, you can still get 131 hp.

 

Any other ship uses its full hp rating at sea level, and as you gain altitude, you lose HP.....you just can fly higher in an R22 with less loss of HP due to the de-rating of the engine...no matter what, the drivetrain can still only take 131 HP continuous. The governor just looks at your Rotor RPM and gives the engine commands to keep it in the green.....when there is no more for the engine to give, your rotor rpm will start to slow down....also another topic.

 

Fly safe, Goldy

[james28]

so there's no real mechanical part or system that reduces or derates the engines horsepower other than the collective. so like in a car the speedometer reads up to 120mph but the car can really only go 100mph without damaging itself? is it just falsifying the true power that is available? and if you are the one who controls the main power and has the ability to adjust power based on the situation so as not to damage the internals, then why is there a need to derate the engine. i understand what you are saying, it just doesn't make sense.

[Goldy]

so there's no real mechanical part or system that reduces or derates the engines horsepower other than the collective. so like in a car the speedometer reads up to 120mph but the car can really only go 100mph without damaging itself? is it just falsifying the true power that is available? and if you are the one who controls the main power and has the ability to adjust power based on the situation so as not to damage the internals, then why is there a need to derate the engine. i understand what you are saying, it just doesn't make sense.

 

 

OK, let me plant a couple thoughts then maybe someone intellectual can chime in.

 

Yes, you control the power..absolutely. At sea level, the engine is capable of producing much more power than the transmission and rotors can handle. You can pull 180 hp to get it off the ground, but you are overstressing the aircraft and it will fail ( see multiple SN's or read the fatality portion of the NTSB website).

 

De rating just does two things.,1. It allows the engine to normally run at less than maximum HP, so the engine lasts longer, so its a cheaper ship to maintain. 2. Derating allows the engine to continue to put out 131HP at a wider range of altitudes.

 

Remember, it is important that you look at the performance charts in the POH in order to determine the max MP you can pull in any given situation....the whole reason for the charts is so you dont just get in, pull until the red line disappears and off you go. This will work for a period of time...kinda like Russian Roulette...you just never know who will be the pilot when that little crack becomes a big one.

 

Highly suggest the Robinson safety course to fully understand the advantages and limitations.

 

Goldy

 

OH- you dont have to derate the engine. Just fly a Schw.300, the engine works twice as hard, uses full power almost all the time taking off, and has to be completely rebuilt at a cost of about 40K every 1200 hours of use. Its basically the same engine the R22 uses lifting an aircraft that weighs 500 pounds more...The R22 gets 2200 hours for that same 40K...make sense now ?

Edited August 10, 2007 by Goldy

[james28]

gotcha, thanks goldy.

[brushfire21]

OH- you dont have to derate the engine. Just fly a Schw.300, the engine works twice as hard, uses full power almost all the time taking off, and has to be completely rebuilt at a cost of about 40K every 1200 hours of use. Its basically the same engine the R22 uses lifting an aircraft that weighs 500 pounds more...The R22 gets 2200 hours for that same 40K...make sense now ?

 

I believe its higher than 1200 hours (1600?) on the CB version, and 2200 on the Cbi version (back to the derared topic at hand). But I believe the CB version has a bigher OGE hover though, don't have a CBi manual handy though to confim.

[PhotoFlyer]

I'll check the HMI tomorrow, but I think the C is 1600, the CB is 2000, and the CBi is 2200. I'm not sure if those numbers are accurate, but they are the numbers that stuck out in my head.

[Goldy]

I'll check the HMI tomorrow, but I think the C is 1600, the CB is 2000, and the CBi is 2200. I'm not sure if those numbers are accurate, but they are the numbers that stuck out in my head.

 

 

I think the C model is 1500....but Im a robbie guy not a Schweizer guy...The older ships , 269 maybe? I think was at 1200 hrs...but none of that matters...I think James understands the point I was making. I wasnt trying to get the wrath of the 300 club down on me....I could just PM Roger to do that !!

 

ok,ok, just kidding!!!! Stop throwing things !@

 

Goldy

[DonRow]

The C is 1500 TBO cause it runs at a higher RPM, CB is 2,000 TBO, CBi is 2,200 TBO I forgot what the RPM's were on both of um but you are pulling the guts out of the engine on the C something like 3,000 RPM. I've worked on both C and CBi's & Robbie's. I loved working on the Robbie's They will go 100 hr. to 100hr. with no problems. But flying wise my opinion the 300's, it just feels more solid, slow as sh1t but solid.

Edited August 10, 2007 by DonRow

[jet trash]

OH- you dont have to derate the engine. Just fly a Schw.300, the engine works twice as hard, uses full power almost all the time taking off, and has to be completely rebuilt at a cost of about 40K every 1200 hours of use. Its basically the same engine the R22 uses lifting an aircraft that weighs 500 pounds more...The R22 gets 2200 hours for that same 40K...make sense now ?

 

The 300C is derated, from 220hp to 190hp. And it doesn't always "use full power" at takeoff as you have suggested. On a standard day with 2 people and 30 gal fuel it will pick up at around 22-23 inches MP (well below a limit of 27). (the HIO-360-D1A turns 3000-3200 rpm)

 

The only simularity between the R22 engine and the 300C engine is they are made by Lycoming, after that it ends there. Part number for part number, neither engine shares any common parts.

 

The 300C is TBO'd at 1500 hours, and the last engine I rebuilt for one cost me $14,000 to do (add another $4500 for new cylinders)

 

The engines in the CB and CBi are also entirely different, and have a 2000 hour TBO (CB) and 2200 TBO (CBi)

[Collective Down!]

My instructor said that this engine in the Beta II is at 180 horse power but is down rated to 145 horse power.

 

If you compare the O-320 version that the Beta had (160 hp) to the O-360 that the Beta II has (145 hp) you'll probably be just as confused as I was before going to the safety course. How can they get less horsepower out of a larger displacement engine?? The reason is because Lycoming put the 145hp limitation on the O-360-J2A (on the Beta II) because the engine was manufactured with lightweight cylinders to save 6 pounds. That works to Robinson's advantage, because now they have a lighter engine, with a higher altitude capability (I believe full throttle doesn't occur until 9,000 feet), and the derating doesn't affect anything because the drivetrain and rotors etc. are all limited to 131 takeoff HP or 124(?) continuous HP.

 

The concept of derating the Robinson engine (or the Schweizer 300C's engine for that matter) isn't much different than the operation of a turbine engine. If you go wide-open on a turbine (non FADEC) you'll probably burn or break something. It's the pilot's responsibility to note the existing conditions such as temps and altitudes, check the placards, and operate the engine accordingly.

 

 

 

Now this question always gets people fired up (slight pun intended).... If you have the carb heat on in the R22, would you allow yourself to pull a liiittle bit more MP over the placarded limit? I've done a couple experiments by hovering with the carb heat on and off (not exceeding limits, mind you). When the carb heat is on it takes about 1/2 to 1 inch more MP to keep the same hover height. Obviously, you're providing the same amount of torque to the drive train in either case so you can't be hurting anything in the case of carb heat on and using slightly more MP, but some pilots are die-hard placard nazis and would rather settle into the ground than go over the "limit." The only real detriments that the carb heat might be causing are an enriched mixture (resulting in a higher fuel flow for any given operation) and you would lower your ceiling or top speed a little bit.

[PhotoFlyer]

Checked with our mechanic today, 1500 for the C, 2000 for the CB, and 2200 for the CBi is correct.

[Goldy]

Checked with our mechanic today, 1500 for the C, 2000 for the CB, and 2200 for the CBi is correct.

 

Wow- glad we got that settled.

 

How come every post regarding a Robbie turns into a discussion about the 300 ??? Hmmm..conspiracy me thinks.

[PhotoFlyer]

Wow- glad we got that settled.

 

How come every post regarding a Robbie turns into a discussion about the 300 ??? Hmmm..conspiracy me thinks.

 

We Schweizer folk are conspiring with the black helicopters to bring the world TO ITS KNEES!!!! MuHahahahahaha!!! (

Edited August 11, 2007 by PhotoFlyer

[FauxZ]

Now this question always gets people fired up (slight pun intended).... If you have the carb heat on in the R22, would you allow yourself to pull a liiittle bit more MP over the placarded limit? I've done a couple experiments by hovering with the carb heat on and off (not exceeding limits, mind you). When the carb heat is on it takes about 1/2 to 1 inch more MP to keep the same hover height. Obviously, you're providing the same amount of torque to the drive train in either case so you can't be hurting anything in the case of carb heat on and using slightly more MP, but some pilots are die-hard placard nazis and would rather settle into the ground than go over the "limit." The only real detriments that the carb heat might be causing are an enriched mixture (resulting in a higher fuel flow for any given operation) and you would lower your ceiling or top speed a little bit.

 

From the Robbie Course: Full carb heat will add approximately 2000 feet of DA to the performance of the engine.

 

There was no mention of charts or limits so you can make your own call on the legality of pulling more power. However the simple fact is yes, carb heat makes the engine see a higher DA and produce less power for a given MP setting.

[helidave]

but some pilots are die-hard placard nazis and would rather settle into the ground than go over the "limit."

 

 

Technically the limit would change when you added carb heat, because the air going into the engine is warmer.

 

example:

2000ft, 0*C= takeoff power would be 22.5

2000ft, 30*C= takeoff power would be 23.4

 

So you would be pulling more power, but not be over the limit, because the limit is higher due to the warmer air.

[GoodGrief]

edited

Edited August 11, 2007 by GoodGrief