Rocket Cowl Flaps

[Captain Bash]

Howdy!

So, I've always wondered, is that as far as my cowl flaps will go? 

In the Rocket manual it states that the cowl flaps have been adjusted and you will still have about an inch of lever left in the full closed position. That's all well and good but...even with them "fully" closed...they still seem like they are massive doors hanging down. 

As a speed freak, any ideas? Is the trailing position adjustable on these bad boys? I'm sure I could get an extra knot or 2!

Open:

 

Closed:

[Captain Bash]

1 hour ago, philip_g said:

When closed I liked about a quarter inch of trail. Helped cooling. If those photos are supposed to be of them closed, something is amiss. We had a linkage of some sort go bad and cause that, easy fix at the msc

Do you have a Rocket modified 20K? Mine is a '79 so it doesn't have electronic cowl flaps. 

I don't think I could get a 1/4" of trail with my big exhaust pipe.

[aviatoreb]

Your closed pics look a lot like my cowl flaps closed.

[carusoam]

To get more valid feed back...

When discussing how open or closed their cowl flaps are...

Some MSers have put a measuring device at the open end of the flap...

Your choice... inches or centimeters...

Keep in mind...somebody with your answer, may be looking at your pictures with an iPhone.... and can’t tell if your closed picture is the right picture...

Have no fear... there aren’t any Rocket owners that are slow-freaks...

 

Best regards,

-a-

[Captain Bash]

35 minutes ago, carusoam said:

Have no fear... there aren’t any Rocket owners that are slow-freaks...

 

Best regards,

-a-

Hah! 

I feel the need....I'm so pumped for the new Top Gun!

[Captain Bash]

1 hour ago, philip_g said:

hard to find a pic where the lighting is good and the flaps are closed. those were our summer settings, usually adjusted a little more closed for winter.

 

Awesome looking paint job!

I love the setting your cowl flaps are at...I'd love to get mine to that setting. Maybe my AP can figure out how to get it done. 

While I love my AP to death (Local, ex-military, metalhead), he wasnt so sure on how to adjust them when I had him look at them last year

[MIm20c]

I’m not lucky enough to own a rocket but they look like they are adjusted pretty wide. How are the cyl temps?  Any pics of them open...do they look like this

[Captain Bash]

7 minutes ago, MIm20c said:

I’m not lucky enough to own a rocket but they look like they are adjusted pretty wide. How are the cyl temps?  Any pics of them open...do they look like this

Bahahaha!! 

Temps are not an issue. If I'm in "casual" mode (26"MP/2300RPM) they are between 310-325. If I'm at 31"/2400RPM they are 335-360. I am always running my TIT 1575-1600. Cruise speed is 175TAS in casual, 195TAS in normal cruise.

[aviatoreb]

2 hours ago, philip_g said:

hard to find a pic where the lighting is good and the flaps are closed. those were our summer settings, usually adjusted a little more closed for winter.

Now I want to work on my cowl flaps.

[Yooper Rocketman]

As an 18 year Rocket owner I’ve never seen any close as much as @philip_g’s do.   Not saying they’re  wrong.   If your temps work I say great.    Nice paint job too!

I found a common problem was the scissors lineage going over center and then they didn’t work properly (down by the last link rod to the flaps).   I tried several different “stops” on the motor mount tube before getting a good enough one to effectively stop the pull length of the control from pulling past the over center point. Worked very well the last 5+ years.  I also spotted a couple other Rockets with the same issue (unresolved as well).   

Again, I like the closure @philip_g is getting, think it’s great if you can keep cylinder temps under 400, but mine had trouble in the summer avoiding step climbs in the Flight Levels as it was.  The larger open gap in the closed position would be more typical.  

Tom

[Captain Bash]

Awesome, thanks Philip!

Now the mission begins. My annual is in a couple weeks.

Any other Rocket owners intrigued? 

[aviatoreb]

This discussion is making me rethink my cowl flap rigging - if maybe I could tighten it up a bit generally, for speed, but also if maybe I should tighten it up a good bit in the winter not only for speed but also for temps.

The rocket engine, at least mine, runs exceedingly cool.  I never have to worry about step climbs - in the warmest summer flying (ok I live in the far north of the USA and rarely head south of say DC in the summer - I mean who can survive in the seep south in the summer without AC?!) - in the summer I do need to pay attention to temps but with cowl flaps open for climb and controlling pitch/climb speed I can keep even climb temps in the 380's in the summer.  

In the winter, I worry my temps are too cool.  I climb to moderate altitudes even with cowl flaps closed and even at steep climb angles - the joys of life flying when it is 5F ground temps.  And I even tape of a large fraction of the oil cooler to keep some heat in it.  I don't run LOP or low power settings in the winter since I worry the engine is too cold - low 300's or high 200's.  So the last thing I am worrying about is more cooling.  If maybe I can close up my cowl flap rigging a bit and both keep it warmer in the engine area, and get a bit more aerodynamic speed - that's win win.  Who knows, maybe I could skip the oil cooler taping in the winter.  I doubt it - I bet I still need to do that.

[kortopates]

Careful guys, you appear to be comparing cowl flaps between the M20K 231 airframe used by [mention=18503]Captain Bash[/mention] and [mention=8059]aviatoreb[/mention] to the 252 airframe used by [mention=19109]philip_g[/mention] (at least that single pict sure looks like it has the single cowl flap in the middle like an '86 or newer airframe, plus Philip's white panel is clue #2 its a 252 airframe). The 231 has two separate left and right cowl flaps that only has 3 positions: Closed, Trail and Open while the 252 has a single larger one in the middle that is infinitely adjustable between Open and Closed with an electric motor. These are very different style cowl flaps.

Secondly, follow your Mooney Maintenance manual to the T for adjusting cowl flaps; especially the 231 style since Mooney did a lot of testing on these and found the early 231's lost a lot of speed when they overly closed the cowl flaps due to additional turbulence created in front of the inlets. So their rigging instructions are very important about not overly closing them. Not so much an issue with the 252 style but since they are infinitely adjustable there is really no point in making an seasonal adjustments IMO.

 

Edited February 2, 2020 by kortopates

[kortopates]

Ours was a 1983 231.... As I said above. Also obvious in the pics where you can clearly see it's a 12v electrical system.

Ah, my apologies then. Missed that. I sure couldn’t tell that from the photo and was misled by the white panel. Didn’t think to look at voltage.
But second point about importance of following the service manual on rigging so as not to get overly closed still applies.


Sent from my iPhone using Tapatalk

[aviatoreb]

3 hours ago, kortopates said:

Careful guys, you appear to be comparing cowl flaps between the M20K 231 airframe used by [mention=18503]Captain Bash[/mention] and [mention=8059]aviatoreb[/mention] to the 252 airframe used by [mention=19109]philip_g[/mention] (at least that single pict sure looks like it has the single cowl flap in the middle like an '86 or newer airframe, plus Philip's white panel is clue #2 its a 252 airframe). The 231 has two separate left and right cowl flaps that only has 3 positions: Closed, Trail and Open while the 252 has a single larger one in the middle that is infinitely adjustable between Open and Closed with an electric motor. These are very different style cowl flaps.

Secondly, follow your Mooney Maintenance manual to the T for adjusting cowl flaps; especially the 231 style since Mooney did a lot of testing on these and found the early 231's lost a lot of speed when they overly closed the cowl flaps due to additional turbulence created in front of the inlets. So their rigging instructions are very important about not overly closing them. Not so much an issue with the 252 style but since they are infinitely adjustable there is really no point in making an seasonal adjustments IMO.

 

Well that's a disappointing post.  I was kinda getting excited to find 5 kts more of free speed with a minor cowl flap adjustment.  We are always excited if we can discover something that reveals free speed like that.  Truly free if you don't need to buy some speed mod, or whatever.

[Austintatious]

On 2/1/2020 at 11:12 PM, philip_g said:

Never a problem with temps. The rocket baffles are pretty good but I ran rop and fairly conservative tit imo. Ours wouldn't run lop. I can't find any closer to 75 percent at the moment 

Phillip,

Your temps look amazing... In climb my #5 gets hotter than the rest by about 30 degrees.  I am wondering if you have any additional baffles/modifications to airflow to get yours so even?

 

 

[aviatoreb]

3 minutes ago, Austintatious said:

Phillip,

Your temps look amazing... In climb my #5 gets hotter than the rest by about 30 degrees.  I am wondering if you have any additional baffles/modifications to airflow to get yours so even?

Notice the OAT is 12F.

[Austintatious]

15 hours ago, aviatoreb said:

Well that's a disappointing post.  I was kinda getting excited to find 5 kts more of free speed with a minor cowl flap adjustment.  We are always excited if we can discover something that reveals free speed like that.  Truly free if you don't need to buy some speed mod, or whatever.

Well, I think there is a lot of disappointing news for people who are trying to speed mod their aircraft.  

I own half of 2 rockets Two days ago myself and the other owner did some formation flying to directly compare the performance of the two aircraft.

Rocket 1 has a blade antenna, 1 piece belly, no Static wicks, brand new paint and the entry step

Rocket 2 has a towel bar antenna, stock belly, Static wicks, older paint and NO entry step

At 8500 feet the performance was identical.  Both of us running 33/2200 we were spot on speed wise.

[Austintatious]

Just now, aviatoreb said:

Notice the OAT is 12F.

I know, but no matter the temp, #5 is still hot.

[aviatoreb]

19 minutes ago, Austintatious said:

I know, but no matter the temp, #5 is still hot.

Right - but I was pointing out how the question of how well cooled an airplane is may be different in terms of acting on it when it is 12F vs 98F OAT.

I have no problem with enough cooling as I said.  Cowl flaps open and perhaps a cruise climb speed can cure any summer time heat issue. In winter I'm taping off the oil cooler and often climbing with cowl flaps closed.

[aviatoreb]

23 minutes ago, Austintatious said:

Well, I think there is a lot of disappointing news for people who are trying to speed mod their aircraft.  

I own half of 2 rockets Two days ago myself and the other owner did some formation flying to directly compare the performance of the two aircraft.

Rocket 1 has a blade antenna, 1 piece belly, no Static wicks, brand new paint and the entry step

Rocket 2 has a towel bar antenna, stock belly, Static wicks, older paint and NO entry step

At 8500 feet the performance was identical.  Both of us running 33/2200 we were spot on speed wise.

That is very interesting.  Thanks.  I was sort of wishing for blade antenna, but maybe I will stop wishing.  The only thing that has stopped me in the past from getting blade antenna - or worse! hiding the VOR antenna in the wing tips - is that I figure at some point the VOR infrastructure gets decommissioned.  I don't want to be that guy who buys the best most modern LORAN receiver 2 weeks before LORAN got decommissioned.

Did you mean 30/2200?  since 33/2200 is not a book setting and seems like pretty high pressure for that lower rpm, or is that a LOP setting?

But then - why are you co-owning 2 half rockets?  Why not own one full rocket?

[Captain Bash]

Well boys, there's only one way to solve this mystery...

MS Rocket Race! 

[Captain Bash]

Eh, I cant really complain. It's still a quick airplane for sure. Gotta love a 13 knot tailwind.

https://flightaware.com/live/flight/N513SB/history/20200202/2045Z/KUDD/KFFZ/tracklog

I just wish i could get the TAS that rocket said is possible at that altitude...i wish they were honest lol. I'll always be yearning for that extra 10 knots. 

[Austintatious]

7 hours ago, aviatoreb said:

That is very interesting.  Thanks.  I was sort of wishing for blade antenna, but maybe I will stop wishing.  The only thing that has stopped me in the past from getting blade antenna - or worse! hiding the VOR antenna in the wing tips - is that I figure at some point the VOR infrastructure gets decommissioned.  I don't want to be that guy who buys the best most modern LORAN receiver 2 weeks before LORAN got decommissioned.

Did you mean 30/2200?  since 33/2200 is not a book setting and seems like pretty high pressure for that lower rpm, or is that a LOP setting?

But then - why are you co-owning 2 half rockets?  Why not own one full rocket?

It isn't a rocket book number true... however in the manual for the TSIO520NB, it is an acceptable MP/RPM combination.  It seems to work well and is below the 78% (240hp) max cruise power setting.   About  215 HP.  according to the book chart.  TIT at about 1600 around 17.5-18 GPH.  This results in a solid 200 knots at FL180 and about 2 more knots per 1000 feet above that.  CHT's in cruise at those altitudes around 360 (380 on #5)

I wish I could get her to run LOP... no luck so far.  Only at very low (55%) power am I able to achieve LOP.   I have Gami's, but with the crummy engine monitor I have, I have been unable to get a gami spread reading that I would trust, so they have not been fine tuned.

 

I was going to do an EDM900, but I am holding off for now.  I am keeping an eye on Dynon as they will soon have their AP approved for mooney... I may end up just putting their entire package in the aircraft.  I am fed up with garmin.

[aviatoreb]

2 hours ago, Austintatious said:

It isn't a rocket book number true... however in the manual for the TSIO520NB, it is an acceptable MP/RPM combination.  It seems to work well and is below the 78% (240hp) max cruise power setting.   About  215 HP.  according to the book chart.  TIT at about 1600 around 17.5-18 GPH.  This results in a solid 200 knots at FL180 and about 2 more knots per 1000 feet above that.  CHT's in cruise at those altitudes around 360 (380 on #5)

I wish I could get her to run LOP... no luck so far.  Only at very low (55%) power am I able to achieve LOP.   I have Gami's, but with the crummy engine monitor I have, I have been unable to get a gami spread reading that I would trust, so they have not been fine tuned.

 

I was going to do an EDM900, but I am holding off for now.  I am keeping an eye on Dynon as they will soon have their AP approved for mooney... I may end up just putting their entire package in the aircraft.  I am fed up with garmin.

I am a little worried about that setting since Continental came out with a SB a few years ago warning against the rpm settings formerly part of their years of performance charts, including 2200 rpm.  But I presume the issue is worse at higher MP pressures.  I have converted my practices since several years that Im only running 2200 at very low settings like the 26'' 55% setting but I no longer bother with the 2200-30'' setting 65% but I skip straight to 2300-30''.  And on up from there.  Anyway not critiquing you but just FYI in case you never saw this SB.

http://www.tcmlink.com/pdf2/CSB09-11A.pdf