Advice on climbing to FL240

[RocketAviator]

Never heard of that AD?  Been running mine in cruise at 2300 / 30" for 1870 hours?  Hard to believe three different shops and  three IA's missed that.  Do you have the AD number?

 

I just went on the FAA's website  with the AD listings and nothing for the TSIO520NB or for the M20K in regards to RPM limitations.

Last year at Oshkosh I spent an extraordinary amount of time with the Continental Motor Master they told me.

The 520 is yo be run at full RPM at take off and There is no 2300 RPM limit on the Rocket 520.

[jlunseth]

The fuel flow system is set up to provide extra fuel at full power.  If you do not climb at full rich, full throttle, full RPM, you will not get that extra fuel. If you back any of those three parameters off, the fuel system will not put out the max flow the engine needs. There is nothing wrong with a cruise climb at reduced power and leaned a little provided the temps stay low, but if the temps go up the cure is to go to full throttle, full fuel, full RPM's, which is sort of counterintuitive.  It is intuitive to think of that as producing more power and therefore more heat.  However, the rich fuel flow does not "wash" heat out of the cylinders.  It slows the rate of combustion in the cylinder by providing a mixture that is richer than a stoichiometric mixture, and by slowing the rate of combustion it reduces the internal cylinder pressure and thus the heat. 

 

Unfortunately, normally aspirated procedures do not translate to a turbo aircraft, and we all learn in normally aspirated aircraft so we need to learn something different for turbo ops.

 

I would check your baffling and the fuel nozzle though, if changing the temp probe does not solve the difference of the higher temp in #6.  That would be one of the two forward cylinders, exposed to the most airflow, and should be as cool as or cooler than that back cylinders.

[Houman]

Last year at Oshkosh I spent an extraordinary amount of time with the Continental Motor Master they told me.

The 520 is yo be run at full RPM at take off and There is no 2300 RPM limit on the Rocket 520.

I think it was on the prep, I will take a look later, I usually run the prop at 2400 RPM according to the following :

http://www.rocketengineering.com/sites/all/docs/305Rocket.pdf

[Houman]

The fuel flow system is set up to provide extra fuel at full power.  If you do not climb at full rich, full throttle, full RPM, you will not get that extra fuel. If you back any of those three parameters off, the fuel system will not put out the max flow the engine needs. There is nothing wrong with a cruise climb at reduced power and leaned a little provided the temps stay low, but if the temps go up the cure is to go to full throttle, full throttle, full RPM's, which is sort of counterintuitive.  It is intuitive to think of that as producing more power and therefore more heat.  However, the rich fuel flow does not "wash" heat out of the cylinders.  It slows the rate of combustion in the cylinder by providing a mixture that is richer than a stoichiometric mixture, and by slowing the rate of combustion it reduces the internal cylinder pressure and thus the heat. 

 

Unfortunately, normally aspirated procedures do not translate to a turbo aircraft, and we all learn in normally aspirated aircraft so we need to learn something different for turbo ops.

 

I would check your baffling and the fuel nozzle though, if changing the temp probe does not solve the difference of the higher temp in #6.  That would be one of the two forward cylinders, exposed to the most airflow, and should be as cool as or cooler than that back cylinders.

You are absolutely right, I was waging a losing war on trying to reduce the MP but staying full rich and the temp just keep going up until the EDM flashed at a CHT of 425 for #6, at that point, I decided to call it quits, stabilized and came back home with a shallow decent to cool things off slowly.

I will have a look at #6 soon !

Thanks !

[RocketAviator]

Would be very surprised if anything is wrong with #6. Because of this thread I'm going to fly at FL23 or FL25 from 5T6 to Houston next week I'll let you know the results.

I would recommend you take off and climb at full MP 2700 full RPM full rich, cowl flaps full open all the way to FL24 or if you prefer dial back to 2500 or 2500, after that don't adjust your power settings. I'm betting you go all way with no heating issues. Do make sure you put on and check your mask on the ground it takes me less than 20 min to hit FL20 on cool spring days.

[Yooper Rocketman]

2700 RPM?  Max certified RPM for the Rocket is 2650.  I asked my IA if we could adjust to 2700 and he said that would violate the STC.

[RocketAviator]

2700 RPM?  Max certified RPM for the Rocket is 2650.  I asked my IA if we could adjust to 2700 and he said that would violate the STC.

I believe your right my bad...

Assuming your plane governor is setup correctly simply firewall all three knobs!

I have all but MP set before I pull onto active runway, then ease throttle in gradually all the way to 33GPH at take off.

I've flown multiple times up to FL21 22 & 23 no issues. Don't recall ever hitting FL24.

Fly safe all

[Yooper Rocketman]

I did see 44 inches once on takeoff  about a year after I bought the plane.  It had been creeping over 38" a few times, and usually when cold.  Ended up sending the waste gate out for overhaul.  It was easy to tell, as the engine didn't like the high MP at all (stumbled a bit). A few AMU's fixed that problem (did the turbo at the same time).

[RocketAviator]

I flew 1st leg from 5T6 to KBAZ at FL23

Climbed at 1200ft/min all the way full fuel 2 people & ample luggage

TAS 240

GS reached a high of 288 GS during decent.

But really at level flight a GS of 245 to 260kts.

No CHT issues climbed at 31gph 140ish 1200ftm 36mp 2500 rpm

Cursing at 15.8 LOP 348 highest CHT

That's all folks

For those that don't trust me check out flight aware!

Fly safe!

[carusoam]

L,

Any challenges with O2 throughout the flight?

Those numbers are spectacular!

Best regards,

-a-

[aviatoreb]

I flew 1st leg from 5T6 to KBAZ at FL23

Climbed at 1200ft/min all the way full fuel 2 people & ample luggage

TAS 240

GS reached a high of 288 GS during decent.

But really at level flight a GS of 245 to 260kts.

No CHT issues climbed at 31gph 140ish 1200ftm 36mp 2500 rpm

Cursing at 15.8 LOP 348 highest CHT

That's all folks

For those that don't trust me check out flight aware!

Fly safe!

 

Wow - you got 240TAS on 15.8LOP?  What was the MAP, and rpm, and TIT?

[Houman]

Wow - you got 240TAS on 15.8LOP?  What was the MAP, and rpm, and TIT?

He must mean GS not TAS... I would imagine...

[aviatoreb]

He must mean GS not TAS... I would imagine...

 

A balloon can do 250GS if there is enough tailwind wind. 

[RocketAviator]

My bad it was 210kts TAS @ 15.8 gph.

The GS you can ck on flight aware.

MP 35

2400 RPM

[RocketAviator]

L,

Any challenges with O2 throughout the flight?

Those numbers are spectacular!

Best regards,

-a-

No problem at all, we had standby O2 wore masks as you can see. Constant O2 meter checks, never either of us below 98%

[RocketAviator]

Check out flight aware for the flight GS & flight profile.

Enjoyed it, bought another mask today at SnF so can get High with my wife...LOL

[Danb]

What mask did you get..I hate wearing mine, use cannulas as much as possible..a pirep would be handy..

[Danb]

I'm bad I see the mask in the picture same as mine..does your speaker and mike work ok

[M20F]

I'm bad I see the mask in the picture same as mine..does your speaker and mike work ok

Have the same one and it works great and prefer it over a cannula, though generally if I am going to be on O2 I am going be around FL190 so need the mask anyways.

[aviatoreb]

No problem at all, we had standby O2 wore masks as you can see. Constant O2 meter checks, never either of us below 98%

 

I have the same blue masks with nice built in mikes, but mine have some kind of diffuser, so there is no bag hanging down from the chin.  Over all I like the masks pretty well, and they give that fighter pilot look.

 

To anyone using cannulas up to 18k, I highly recommend you look at the oxyarm that attaches to your headset - much more comfortable in my opinion that what is standard and goes around your neck.

[aviatoreb]

My bad it was 210kts TAS @ 15.8 gph.

The GS you can ck on flight aware.

MP 35

2400 RPM

 

Aha - I figured your MP was pretty high - My engine is well balanced and runs nicely and smoothly LOP, but I can't seem to push that much fuel through the system (and remembering when you are LOP that fuel translates proportionally directly to HP) without my TiT getting hotter than I would like.  SO I usually am looking at more like no more than 13 or 13gph LOP trying to keep my TiT below 1600 (an arbitrary line in the sand I placed) which sometimes means I am deep in the LOP so giving up some power.

[aaronk25]

Why operate at less than 1650 max tit? I see I instructors teaching this but is there any real proven results that operating at under max tit prolongs the life of the exhaust components?

[carusoam]

Aaron,

There is a temperature that will start to erode the vanes of the turbine wheel...

The challenge is knowing what the actual turbine temperature is. TIT is as close of a measurement that is available.

Picking a TIT that works reliably to protect all exhaust parts is helpful.

It is probably best to use the specific recommendation of people with the same engine, turbo, and exhaust...

Modern POH and STCs are pretty helpful.

The costs of going very fast....

Is that in line with what you are asking?

Best regards,

-a-

[aviatoreb]

Why operate at less than 1650 max tit? I see I instructors teaching this but is there any real proven results that operating at under max tit prolongs the life of the exhaust components?

 

I just don't know what is actually a good idea.  So I figure adding a conservative safety margin is a good idea.

 

According to Deakins  - he says that turbine operations are what counts when it comes to turbo's TIT and that there is nothing wrong with operating at TiT max all day long.  But I just can't bring myself to do it.

 

At 15.8gph that works out to 65% of 305hp.  According to POH I run 65% ROP at 18gph - and Tit is a lot closer to 1500.  Although CHTs are cooler at the same power setting LOP vs ROP even though power is the same - and likewise as we see fuel consumption is lower.  Cooler CHTs are apparently due to lower ICPs (pressure).  So even though the ROP setting (30'' and 2200rpm, 18gph) for 65% power (200hp) is the same power as 65% LOP you are getting (35'' 24000rpm, 15.8gph) the pressure of the combustion event is lower since they say that the combustion event is slower.  Less of a hammer hit.  If I could only be convinced that there is no problem running 1650 day in and day out, then all other indicators is that this is a better way.

 

Then again - for the same power - if you are saving 2.2gph per hour, that's $11 per hour.  Lets say (making stuff up now) you need exhaust work and turbo work at 500 hours instead of 1000 hours - so you loose 500 hours - then that's 5500 saved in gas and that's probably ball park the cost of the work.  Of course no one really knows the delta here.  And you can argue that what's lost in exhaust life is gained in engine life - cylinders etc.  ...I just don't know.

 

Mostly I only run LOP when I want to extend range, and it especially extends range since I usually only do it at very low power settings. 

[aaronk25]

I just don't know what is actually a good idea. So I figure adding a conservative safety margin is a good idea.

According to Deakins - he says that turbine operations are what counts when it comes to turbo's TIT and that there is nothing wrong with operating at TiT max all day long. But I just can't bring myself to do it.

At 15.8gph that works out to 65% of 305hp. According to POH I run 65% ROP at 18gph - and Tit is a lot closer to 1500. Although CHTs are cooler at the same power setting LOP vs ROP even though power is the same - and likewise as we see fuel consumption is lower. Cooler CHTs are apparently due to lower ICPs (pressure). So even though the ROP setting (30'' and 2200rpm, 18gph) for 65% power (200hp) is the same power as 65% LOP you are getting (35'' 24000rpm, 15.8gph) the pressure of the combustion event is lower since they say that the combustion event is slower. Less of a hammer hit. If I could only be convinced that there is no problem running 1650 day in and day out, then all other indicators is that this is a better way.

Then again - for the same power - if you are saving 2.2gph per hour, that's $11 per hour. Lets say (making stuff up now) you need exhaust work and turbo work at 500 hours instead of 1000 hours - so you loose 500 hours - then that's 5500 saved in gas and that's probably ball park the cost of the work. Of course no one really knows the delta here. And you can argue that what's lost in exhaust life is gained in engine life - cylinders etc. ...I just don't know.

Mostly I only run LOP when I want to extend range, and it especially extends range since I usually only do it at very low power settings.

Thanks for the info...exactly what I was asking for. My next mooney will be a tks rocket, so that's why I ask/ challenge some ideas.

I can't find any other plane that is as fast at that fuel flow, without major sacrifices.