Power settings and performance for rocket (Not cruise)

[wombat]

So as I'm getting used to my new plane, I'm trying to find the power settings I like for some of the parts of the flight, like the traffic pattern, and final approach.

I've got the "IFR By the Numbers" sheet for the rocket, and either my plane has issues or something, because at least one of the numbers doesn't match up at all.

It claims that 2200 RPM and 20" of manifold pressure  with gear down and flaps up will result in level flight at 105 Kts....   That's not even close for me.  In order to achieve 105 Kts level flight with the gear down, I've got to have about 27" of manifold pressure.

 

Does anyone else with a rocket have a list of these settings and performance numbers so I don't have to go out and figure them out for myself?   Also, if you *do* get level flight @ 105 Kts with the gear extended at 20" of manifold pressure, please let me know because there is obviously something VERY wrong with my plane.   Yikes!  The plane seems to perform fine in cruise, getting 190KTAS to 200KTAS at the lower power cruise settings from the Rocket table on the visor in the 8,000' to 17,000' range.

 

The power settings & airspeeds I would really like is for the traffic pattern downwind, base and final.

 

[SteveB]

I have 2,000+ hours in my Rocket over the last 21 years. I use it several times a week to commute between offices in the SF area over a distance of around 55 miles. The flights are all at 4500 and 5500 ft. and are affected by gusty winds over the Oakland Hills and the MAyacama Mountains. Thus, I am encouraged to keep the speed down and putter along. 

In the cruise portion of my flights I use 27MP and 2200RPM. I obtain 154kph indicated. I lean to 75deg. rich or around 17gph. I could go faster but the bumps would be more emphatic and I would be close to or in the yellow arc. I keep it leaned out on descent and landing (unless there are thoughts of a possible go-around) and religiously pull the power back in 2" increments per minute. 

The result of this operating procedure is that engine #1 went to 2400 hours and the mechanic on the last oil change noted from the oil analysis the engine looked like a teenager. It was still using a qt. every 10 hours.

This procedure is comfortable for me but I would appreciate any input - but forget the "you should fly a 201" comments. I like the Rocket. It is a wonderful plane. The extra power is always there when one needs it. It is a good instrument platform allowing me to do the ILS at anything between 100kt and 150kt to fit in with the commercial traffic at Oakland every morning. Pilots are commonly lusting over the next plane and I have felt guilty for not joining them but I have considered "moving up" and, as long as I am not compelled by ice protection or pressurization, there is no piston single to move up to and I have yet to convince my wife of the wisdom of a TBM.

Steve

[Fly Boomer]

18 minutes ago, SteveB said:

I have 2,000+ hours in my Rocket over the last 21 years. I use it several times a week to commute between offices in the SF area over a distance of around 55 miles. The flights are all at 4500 and 5500 ft. and are affected by gusty winds over the Oakland Hills and the MAyacama Mountains. Thus, I am encouraged to keep the speed down and putter along. 

In the cruise portion of my flights I use 27MP and 2200RPM. I obtain 154kph indicated. I lean to 75deg. rich or around 17gph. I could go faster but the bumps would be more emphatic and I would be close to or in the yellow arc. I keep it leaned out on descent and landing (unless there are thoughts of a possible go-around) and religiously pull the power back in 2" increments per minute. 

The result of this operating procedure is that engine #1 went to 2400 hours and the mechanic on the last oil change noted from the oil analysis the engine looked like a teenager. It was still using a qt. every 10 hours.

This procedure is comfortable for me but I would appreciate any input - but forget the "you should fly a 201" comments. I like the Rocket. It is a wonderful plane. The extra power is always there when one needs it. It is a good instrument platform allowing me to do the ILS at anything between 100kt and 150kt to fit in with the commercial traffic at Oakland every morning. Pilots are commonly lusting over the next plane and I have felt guilty for not joining them but I have considered "moving up" and, as long as I am not compelled by ice protection or pressurization, there is no piston single to move up to and I have yet to convince my wife of the wisdom of a TBM.

Steve

Excellent first post!  We have so few Rocket people on MooneySpace, we need all we can get.  Thanks.

[Fly Boomer]

On 7/14/2023 at 9:44 AM, wombat said:

The power settings & airspeeds I would really like is for the traffic pattern downwind, base and final.

Check the response to your query from @SteveB above.  Sounds like a great resource.

[Austintatious]

On 7/14/2023 at 9:44 AM, wombat said:

So as I'm getting used to my new plane, I'm trying to find the power settings I like for some of the parts of the flight, like the traffic pattern, and final approach.

I've got the "IFR By the Numbers" sheet for the rocket, and either my plane has issues or something, because at least one of the numbers doesn't match up at all.

It claims that 2200 RPM and 20" of manifold pressure  with gear down and flaps up will result in level flight at 105 Kts....   That's not even close for me.  In order to achieve 105 Kts level flight with the gear down, I've got to have about 27" of manifold pressure.

 

Does anyone else with a rocket have a list of these settings and performance numbers so I don't have to go out and figure them out for myself?   Also, if you *do* get level flight @ 105 Kts with the gear extended at 20" of manifold pressure, please let me know because there is obviously something VERY wrong with my plane.   Yikes!  The plane seems to perform fine in cruise, getting 190KTAS to 200KTAS at the lower power cruise settings from the Rocket table on the visor in the 8,000' to 17,000' range.

 

The power settings & airspeeds I would really like is for the traffic pattern downwind, base and final.

 

 

27 inches to indicate 105 sounds way off...  WAY off...  At 19 inches with my gear down I cant even stay on GS without flaps or speed brakes without blowing past gear speed.   It will be 2 weeks before I fly again, but when I do I will see what it takes for me to hold 105 with gear down in level flight and report back.

 

That being said, I do not have a list to give you, but I can tell you what I do... I climb at FULL POWER to cruise, then set 29/22 burning 17.5 an hour indicating about 143 knots.

I leave that power setting all through the descent until it is time to slow down to land.  The only exception is if I am really stretching fuel as I don't have ER tanks.  In that case, I do a 700 FPM descent and reduce power down to 18-19 inches and about 10 GPH.

I do not worry too much about timing my power reductions IE: 1 inch per min....  I am convinced shock cooling is not an issue for this engine if you are not being crazy.  One of my rockets has a JPI which will alert for too rapid cooling and I never see it even if I pull 3 inches or even more at a time.   I am more concerned with smoothly reducing power as I do so.

So I approach the pattern at 18-19 inches.  I used the boards to slow and get the gear out first, then get the flaps out when I can.  Dont be afraid to slip if you need to kill speed.  I then typically make small adjustments on the power, never going below 16 inches.  Mind you I have not touched the prop or the mixture since I set cruise power...  The only exception being preparing for a possible go around for some reason like reported windshear (this saved my booty once!)

 

from 30 feet down to the ground I smoothly and very slowly reduce the power to idle while trimming up... boards in or out makes little difference with a slight advantage to a nice landing being with boards out... after touchdown I typically suck up my flaps immediately so that the airplane settles and sticks to the ground and I can use the brakes if I need or want.

[dzeleski]

4 minutes ago, Austintatious said:

 

I do not worry too much about timing my power reductions IE: 1 inch per min....  I am convinced shock cooling is not an issue for this engine if you are not being crazy.  One of my rockets has a JPI which will alert for too rapid cooling and I never see it even if I pull 3 inches or even more at a time.   I am more concerned with smoothly reducing power as I do so.

Shock cooling is a myth all together. You can prove it to yourself. Pull the power as far back as you want and descend. Then shut the engine off but leave your engine monitor running. Pull the logs and look at how fast the engine cools when you shut it down.

https://www.avweb.com/ownership/shock-cooling-myth-or-reality/

https://www.avweb.com/ownership/shock-cooling-time-to-kill-the-myth/

[Austintatious]

21 minutes ago, dzeleski said:

Shock cooling is a myth all together. You can prove it to yourself. Pull the power as far back as you want and descend. Then shut the engine off but leave your engine monitor running. Pull the logs and look at how fast the engine cools when you shut it down.

https://www.avweb.com/ownership/shock-cooling-myth-or-reality/

https://www.avweb.com/ownership/shock-cooling-time-to-kill-the-myth/

I am aware, I just didnt want any controversy.

[redbaron1982]

On 7/14/2023 at 9:44 AM, wombat said:

So as I'm getting used to my new plane, I'm trying to find the power settings I like for some of the parts of the flight, like the traffic pattern, and final approach.

I've got the "IFR By the Numbers" sheet for the rocket, and either my plane has issues or something, because at least one of the numbers doesn't match up at all.

It claims that 2200 RPM and 20" of manifold pressure  with gear down and flaps up will result in level flight at 105 Kts....   That's not even close for me.  In order to achieve 105 Kts level flight with the gear down, I've got to have about 27" of manifold pressure.

 

Does anyone else with a rocket have a list of these settings and performance numbers so I don't have to go out and figure them out for myself?   Also, if you *do* get level flight @ 105 Kts with the gear extended at 20" of manifold pressure, please let me know because there is obviously something VERY wrong with my plane.   Yikes!  The plane seems to perform fine in cruise, getting 190KTAS to 200KTAS at the lower power cruise settings from the Rocket table on the visor in the 8,000' to 17,000' range.

 

The power settings & airspeeds I would really like is for the traffic pattern downwind, base and final.

 

Most likely y'all have this document already, but I was not aware of it and I find very it interesting: https://www.clubcherokee.com/wp-content/uploads/2015/07/Mooney.pdf

It has loads of information, including "the IFR numbers" for many, if not all, Mooney's. 

Edited August 22, 2023 by redbaron1982

[wombat]

Thanks, @redbaron1982 that doc and @Austintatious for your info and to @SteveB for joining in!

The climb and cruise numbers match for me fairly well, but that IFR/MDA Level number is just way off.     20" MP with flaps and gear down will probably result in a stall if I try to maintain level flight.

 

Do any of you have a power setting you use for a downwind  traffic pattern leg with the gear out?  Or the descent portion of the traffic pattern?   I personally like having a number I try to use consistently so that way if I'm off on performance I can tell it immediately.

 

So far I'm obeying all of the instructions from the Mooney performance chart  like the 1" per minute reduction, minimum 25" on descent, cruise power and fuel flow settings and temps.   And while the last time I flew I didn't quite get the climb performance in the chart, the ambient temperatures were quite high.   The cruise performance is within what I would consider a normal range (about 190KTAS to 205KTAS at 31" 2,300 RPM at 12,500 to 17,500)

When I get more time available, I'll test out the other performance numbers.    

 

The chart I am talking about is the one from @Jsavage3 here.  

 

Edited August 22, 2023 by wombat

[mgtrevor]

I agree 27 inches sounds too high.  I find the IFR by the numbers chart pretty close.  

Pattern-wise: If I drop the gear at about 138, it will slow to around 112 level pretty quickly.  I fly the pattern using 18-20 inches, using the lower-end to get to flap speed.  That might be fast depending on who else is in the pattern with you.   15 inches down final modulating for glideslope as needed.

And if you need to go around, start trimming down quickly and aggressively.

 

 

[kortopates]

[mention=12280]wombat[/mention] If you need 27” for the traffic pattern down wind you probably have a leak in your manifold pressure sensing line; especially when high manifold setting are fine but but low ones aren’t. To be sure check what your idle manifold pressure is at idle rpm.


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[Fly Boomer]

17 hours ago, wombat said:

Thanks, @redbaron1982 that doc and @Austintatious for your info and to @SteveB for joining in!

The climb and cruise numbers match for me fairly well, but that IFR/MDA Level number is just way off.     20" MP with flaps and gear down will probably result in a stall if I try to maintain level flight.

 

Do any of you have a power setting you use for a downwind  traffic pattern leg with the gear out?  Or the descent portion of the traffic pattern?   I personally like having a number I try to use consistently so that way if I'm off on performance I can tell it immediately.

 

So far I'm obeying all of the instructions from the Mooney performance chart  like the 1" per minute reduction, minimum 25" on descent, cruise power and fuel flow settings and temps.   And while the last time I flew I didn't quite get the climb performance in the chart, the ambient temperatures were quite high.   The cruise performance is within what I would consider a normal range (about 190KTAS to 205KTAS at 31" 2,300 RPM at 12,500 to 17,500)

When I get more time available, I'll test out the other performance numbers.    

 

The chart I am talking about is the one from @Jsavage3 here.  

 

Where did the "IFR By The Numbers" document come from?  The title (231, 252, and Rocket) seems to include all pre-Encore M20K models, but the 200+ kts at cruise could only apply to the Rocket.  Was this single page extracted from a larger document and, if so, do you have the entire document?

[redbaron1982]

3 hours ago, Fly Boomer said:

Where did the "IFR By The Numbers" document come from?  The title (231, 252, and Rocket) seems to include all pre-Encore M20K models, but the 200+ kts at cruise could only apply to the Rocket.  Was this single page extracted from a larger document and, if so, do you have the entire document?

It's an extract from this:  https://www.clubcherokee.com/wp-content/uploads/2015/07/Mooney.pdf

I have added that link already in this thread.

[wombat]

When I'm at idle on the ground it's showing about 13" to 15" MP.   

I got some advice to double-check my fuel flow at the 27" MP level flight, to make sure it's really producing the expected power.  So next time I go fly solo I'll check that out.

 

@Fly Boomer The title on that page is misleading, on the previous page they have M20K 231, and the next page is M20K 252 so I think they should have titled this page "M20K 305 Rocket (Converted from either 231 or 252)" or something like that.

[kortopates]

Where did the "IFR By The Numbers" document come from?  The title (231, 252, and Rocket) seems to include all pre-Encore M20K models, but the 200+ kts at cruise could only apply to the Rocket.  Was this single page extracted from a larger document and, if so, do you have the entire document?

It comes from the MAPA Safety Foundation PPP’s - all participants get a copy.


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[Fly Boomer]

2 hours ago, redbaron1982 said:

It's an extract from this:  https://www.clubcherokee.com/wp-content/uploads/2015/07/Mooney.pdf

I have added that link already in this thread.

Thanks.  I have some reading to do!

[FloridaMan]

I've got around 900 hours in my Rocket over 5 years. A couple operational things really stand out with those numbers. Firstly, I don't fly with gear down and less than prop full forward. If my gear's down, it means I'm on approach to landing, which means I need to be ready for a go around so my prop will be full forward. I also fly my instrument approaches at around 120kts. If it's a GPS approach, MDAs are generally a bit higher and if it's an ILS, I'll have at least a couple thousand feet of runway as airports with ILS approaches tend to have at least 5000ft of runway and I can get rid of that airspeed once I've got the runway in sight. 

My approach power configuration is prop full forward and 15" of mp. I usually land with the speed brakes extended. Home airport is 2800ft runway with high DA and I have single piston brake calipers and she likes to roll a few hundred feet after touching down. I often will use a little rudder before the touch so I can set one wheel down first to cushion the landing and if it feels like I'm about to plop down, I'll take the rudder out and/or add a touch of power for a smooth touch. 

When coming in to land with four people and bags from a short flight, when she gets below around 100kts, it sometimes requires full power to arrest a descent with the gear down in a banked turn. Don't be afraid to add as much power as it takes. I climb at 100% power until I reach altitude, even if it's FL240; it needs low boost at around FL180 and I need to climb at over 120kias around that altitude for cooling. The book for the TSIO520-NB variant has the performance shown as rated at 100% power continuous; other variants of the engine are limited to 5 minutes or so. https://www.n57825.com/docs/TCM_TSIO520NB.pdf . I do have an EDM900 that shows all CHTs and I climb to keep them under 400 and I keep TIT under 1600. 

Here in Florida, I cannot comfortably fly at 105kts in cruise. It feels like slow flight, efficiency drops and temps go up. I'm running a SureFly emag and fine wires, but no gamijectors yet, and it's tough to run LOP smoothly at higher power settings. The SureFly gives what amounts to an effective timing advance by not having the condenser delay and running at lower RPM helps to facility LOP ops, but I don't really have the discipline to go slow. I typically cruise at 2400/32" except in cases where it can mean avoiding a fuel stop, and I'll go 2300/29" or 2200/26" if I absolutely have to. Down low, I get around 16gph at 2300/29 and that goes closer to 19/20gph up high because of the additional work the turbo has to do, which means higher IAT, which translates to higher EGT/TIT. 

[FloridaMan]

Just another thing to add, TIT seems to reflect in CHTs; my guess is that higher TIT means higher turbo housing temp, which means higher discharge temp and higher IAT from the air that gets BTUs added to it from the turbocharger. And likely why the rocket manual says to climb at 1450 TIT at 100% power and you can cruise at 1600-1650 at low power settings. I’ve heard that the redline temp limitation is about the cast housing of the turbo, but without adequate cooling airflow from slower speeds in the climb, CHTs can’t be maintained — and I suspect it’s a combination of cooling air over the jugs and airflow through the intercoolers. 

[wombat]

I went flying solo yesterday and tried to match the "IFR by the Numbers" performance.

The "Approach Level" was about right and with the gear and flaps up I achieved about 120KT at 20" with 2200 RPM, burning 12.9 GPH.

The "IFR/ILS Descent" was about right and with gear down and flaps up I achieved about 105KT at 15" with 2200 RPM burning about 11 GPH.

The "IFR/MDA Level" was not anywhere close to right, and with the gear down and flaps up, in order to maintain 105KT in level flight I had to have about 27 " of manifold pressure burning about 17 GPH.   See the pictures below.  (Ignore the 200 FPM climb, that was just a gust of wind.)  If you are REALLY curious, you can verify this by looking at my position on the G500 and comparing that to the ADS-B data from Flightaware, that section was in the 13 min to 14 min time frame on the ADS-B track.

 

  The clean level flight and clean climb performance numbers I see very closely match the POH and the IFR sheet.  Since the IFR sheet's descent with gear extended performance numbers match my plane I conclude that the gear is not causing significant additional drag compared to how much it should produce.  My conclusion on this is that the sheet is likely wrong.

[Austintatious]

Does your gear have the hubcaps?  Do you have the under wing fairings for the main gear?

I am about to head to the field to do some work, will probably fly afterwords... I'll report what MP I need to be at 105 with gear down flaps up.

[Austintatious]

On 8/24/2023 at 5:24 PM, FloridaMan said:

I've got around 900 hours in my Rocket over 5 years. A couple operational things really stand out with those numbers. Firstly, I don't fly with gear down and less than prop full forward. If my gear's down, it means I'm on approach to landing, which means I need to be ready for a go around so my prop will be full forward. I also fly my instrument approaches at around 120kts. If it's a GPS approach, MDAs are generally a bit higher and if it's an ILS, I'll have at least a couple thousand feet of runway as airports with ILS approaches tend to have at least 5000ft of runway and I can get rid of that airspeed once I've got the runway in sight. 

My approach power configuration is prop full forward and 15" of mp. I usually land with the speed brakes extended. Home airport is 2800ft runway with high DA and I have single piston brake calipers and she likes to roll a few hundred feet after touching down. I often will use a little rudder before the touch so I can set one wheel down first to cushion the landing and if it feels like I'm about to plop down, I'll take the rudder out and/or add a touch of power for a smooth touch. 

When coming in to land with four people and bags from a short flight, when she gets below around 100kts, it sometimes requires full power to arrest a descent with the gear down in a banked turn. Don't be afraid to add as much power as it takes. I climb at 100% power until I reach altitude, even if it's FL240; it needs low boost at around FL180 and I need to climb at over 120kias around that altitude for cooling. The book for the TSIO520-NB variant has the performance shown as rated at 100% power continuous; other variants of the engine are limited to 5 minutes or so. https://www.n57825.com/docs/TCM_TSIO520NB.pdf . I do have an EDM900 that shows all CHTs and I climb to keep them under 400 and I keep TIT under 1600. 

Here in Florida, I cannot comfortably fly at 105kts in cruise. It feels like slow flight, efficiency drops and temps go up. I'm running a SureFly emag and fine wires, but no gamijectors yet, and it's tough to run LOP smoothly at higher power settings. The SureFly gives what amounts to an effective timing advance by not having the condenser delay and running at lower RPM helps to facility LOP ops, but I don't really have the discipline to go slow. I typically cruise at 2400/32" except in cases where it can mean avoiding a fuel stop, and I'll go 2300/29" or 2200/26" if I absolutely have to. Down low, I get around 16gph at 2300/29 and that goes closer to 19/20gph up high because of the additional work the turbo has to do, which means higher IAT, which translates to higher EGT/TIT. 

Some good info here and I see similar numbers but I more typically climb at 130 KIAS and try to stay at 380 CHT or less.

I am confused about the bold however.  I don't think the higher TIT at higher altitudes is because of the increased IAT but rather because the wastegate progressively closes sending more and more exhaust gas to the turbine side of the turbocharger.   

As I understand it, the IAT indication  is  a remnant from before the rocket mod.  The temp is taken before the inter-coolers (which did not exist prior to rocket mod) and is a useless indication because of the inter-coolers.

[wombat]

18 minutes ago, Austintatious said:

Does your gear have the hubcaps?  Do you have the under wing fairings for the main gear?

I am about to head to the field to do some work, will probably fly afterwords... I'll report what MP I need to be at 105 with gear down flaps up.

No hubcaps, but yes to under-wing fairing.

 

As an aside, I have not had an autopilot at all for 6+ years, and the one I had before this was an S-Tec system 30 that didn't have electric trim for its altitude hold, and I'm super happy with having a full autopilot.   I can just hit the altitude hold button and adjust power for the airspeed I want.   Amazing!!!

[Fly Boomer]

How would I know if I had the "under wing fairings for the main gear"?  Got a picture?  Mine was a 252 before Rocket.  BTW, these are great numbers you guys are providing.

[Stetson20]

Another data point (take it for what it's worth):

I've only had a few flights recently and I climbed out using the autopilot. I set 500fpm climb and use 35/2500. Fuel flow is (if I recall correctly) about 28 GPH. Every flight is a learning experience. I'm finally getting to fly my plane more often.

Recent flight was HEG-ILM for about 2.0 enroute. I cruise about 65% power at 1500 TIT. 28/2300 or thereabouts, between 8k and 10k, resulting in about 18gph ff. I haven't worked my way up to using O2 and flying above 11k yet. 

[JoshK]

Another data point (take it for what it's worth):
I've only had a few flights recently and I climbed out using the autopilot. I set 500fpm climb and use 35/2500. Fuel flow is (if I recall correctly) about 28 GPH. Every flight is a learning experience. I'm finally getting to fly my plane more often.
Recent flight was HEG-ILM for about 2.0 enroute. I cruise about 65% power at 1500 TIT. 28/2300 or thereabouts, between 8k and 10k, resulting in about 18gph ff. I haven't worked my way up to using O2 and flying above 11k yet. 

Good datapoint, thank you.

Here’s another you might try that I have been really liking lately for just cruising along in no particular hurry… though in a Rocket it’s still ~40kt faster than the Arrow I came out of

It’s LOP for sure, and this is at 11,500 with the cowl flap closed completely. True at 171/172kt

I was sent a photo from a friend recently that makes me think my main gear doors need to be re-rigged which I suspect will improve speed several knots from talking to Marauder. If his estimates from his F model experience are anything to go off then deriving the gear doors might push me closer to 180 than 175.




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