252 Cruise Speed

[squeaky.stow]

According to this article by a former Mooney test pilot, the 231 is about 10-12 knots slower than the 252. If true, then you are right in the ballpark at 65%.

http://www.mooneypilots.com/mapalog/M20K252_evaluation_report.htm

By the way, I came very close to making an offer on C-FLQQ before you bought it. It looked like a great airplane for a steal of a price! I was not quite ready to commit at that time. Hope you are enjoying it.

Cheers,

Mark

[M016576]

On 10/12/2017 at 12:55 AM, milotron said:

More Canadians! Woo hoo eh!

 

I have a 1981 M20K with the 262 upgrades and TKS so very similar to yours but with 2 blade prop.

My last flight was that altitude out and back and was 160KTAS or so ( although flight aware says it was 173kts...IDK ) .  I also use LOP at 65% and see 10GPH. My GAMI spread is about 0.6GPH so you should have no issue doing that. I see 1600 TIT using 2400 and 25" or so.  I need about 1/3 open cowl to maintain below 380.

I added the fine wires and had better high altitude performance without a doubt. Expensive, but they last forever. Didn't really impact lower LOP ops though.

You noted TIT of 1650. What power setting was that at?

 

iain

Flight aware can only show GS, not KTAS: 173 makes sense for a light tailwind and some altitude

[milotron]

13 minutes ago, M016576 said:

Flight aware can only show GS, not KTAS: 173 makes sense for a light tailwind and some altitude

Understood, but I somehow had the same tail wind there and back, plus ground speed on the GPS was reading closer to KTAS. It was a pretty calm day.  I have noted some other recent optimistic Flightaware readings, similarly making me 20kts faster then reality. The tracklog in Foreflight was correct to my in flight observations though.

 

iain

[milotron]

21 hours ago, milotron said:

I have had some issue with the bolted splice connections between the leads and wiring harness.Sometimes tough to get a good connection with them. In the milli volt range that these run in, it doesn't take much resistance to cause inaccuracy.

I think I need to review my CHT 'issues' on this basis.

 

iain

Further to this, my EDM 700 shows the CHT / EGT as 40 / 41 when cold, with OAT at 6.  All of the cylinders and TIT were consistent at this, presumably JPI doesn't read anything below that range?  What does anybody else's read when cold? Matching OAT?

 

iain

[gsxrpilot]

Here are some of my numbers. I'm flying a 1987 252 with the TSIO 360 MB 210HP engine.  I'm reading TAS from the Aspen and the engine numbers from the JPI EDM-900. Most are ROP.  All are straight and level, on the autopilot, after some time given to settle in. I often take a picture of the Aspen/G5/JPI in flight which captures this data.

TAS - Altitude - OAT - MP - RPM - GPH - %Power
170TAS 10500 10C 28.8MP 2480RPM 14.2GPH 73%
166TAS 10500 13C 27.3MP 2440RPM 13.1GPH 67%
181TAS 16500 3C 29.3MP 2430RPM 14.0GPH 74%
176TAS 12000 13C 30.1MP 2450RPM 13.7GPH 74%
190TAS 21000 -8C 28.4MP 2480RPM 14.4GPH 75%
204TAS 25000 -14C 27.7MP 2490RPM 14.1GPH 74%
176TAS 17500 3C 25.7MP 2430RPM 13.0GPH 65%
159TAS 14000 8C 25.1MP 2480RPM 9.4GPH 61%
185TAS 20000 -6C 25.0MP 2500RPM 12.5GPH 67%

[jackn]

On 10/20/2017 at 2:09 PM, carusoam said:

12.3 gph is ROP for your bird, right?

 

That is correct. Lop would be at 10.4gph for 65%. 

[MIm20c]

@gsxrpilot Do you slightly adjust RPM to change how it leans out?  I’m doing some higher  speed runs all at 2400 or 2500. Not sure if changing the RPM slightly to fine tune for MP and altitude would make a difference. 

[gsxrpilot]

8 minutes ago, MIm20c said:

@gsxrpilot Do you slightly adjust RPM to change how it leans out?  I’m doing some higher  speed runs all at 2400 or 2500. Not sure if changing the RPM slightly to fine tune for MP and altitude would make a difference. 

Truthfully I haven't paid much attention to RPM. I'm typically trying for 2500 RPM as I understand that's where my prop is most efficient. Sometimes I'm a little lower, but I haven't specifically tried different RPM settings.

[Northern Mooniac]

On 10/21/2017 at 3:24 PM, squeaky.stow said:

According to this article by a former Mooney test pilot, the 231 is about 10-12 knots slower than the 252. If true, then you are right in the ballpark at 65%.

http://www.mooneypilots.com/mapalog/M20K252_evaluation_report.htm

By the way, I came very close to making an offer on C-FLQQ before you bought it. It looked like a great airplane for a steal of a price! I was not quite ready to commit at that time. Hope you are enjoying it.

Cheers,

Mark

It's been good! required alot of tweaking, honestly wasn't taken care of very well. Put in an aspen pro 1000, jpi 830, flight stream 210, jsut put on a turbo xp engine warmer, gami's, tempest plugs and had to get the autopilot rebuilt. now it runs pretty awesome. Just working on the kinks, however I still want a 252 with the 305hp mod lol

[N231BN]

How are you guys calculating your true air speed? I am running 33in 10.5gph and 2500 at 10000-12000 ft and getting about 145-150kts. I have intercooler, merlyn, tks and VGS. 
I feel like i’m Missing 10-15kts of speed compared to you guys?

TKS and VGs are going to take that last 10 knots you are missing.

[Northern Mooniac]

Yeah so I’ve heard. Been thinking about taking those vg’s off.... not seeing any benefit really

[aviatoreb]

1 hour ago, Northern Mooniac said:

Yeah so I’ve heard. Been thinking about taking those vg’s off.... not seeing any benefit really

I’ve got vgs and tks also. If you take the vgs off please do before and after speed tests - I’m curious.

my feeling is that tks does damage to the speed but then the damage is mostly done and vg s don’t make it worse.

[squeaky.stow]

I’ve got vgs and tks also. If you take the vgs off please do before and after speed tests - I’m curious.
my feeling is that tks does damage to the speed but then the damage is mostly done and vg s don’t make it worse.

If TKS does cost speed (the company claims it doesn't) I'm certainly not seeing it.
I am seeing POH speeds pretty consistently.
On the other hand, while I certainly don't go out seeking ice in a piston single, it sure is nice to know you can climb out of it or get down safely if you get caught. I couldn't see paying the retrofit costs, but since it came with the airplane for not much of a premium it was a big bonus.
Mark


Sent from my iPhone using Tapatalk

[One Whiskey Hotel]

On 10/21/2017 at 7:58 AM, Northern Mooniac said:

How are you guys calculating your true air speed? I am running 33in 10.5gph and 2500 at 10000-12000 ft and getting about 145-150kts. I have intercooler, merlyn, tks and VGS. 

I feel like i’m Missing 10-15kts of speed compared to you guys?

Perhaps I’m shooting from the hip here, but I’d speculate your VG’s are killing your speed. Anyone here know exactly how much they drag on a laminar flow M20 wing?

[exM20K]

before you go tearing things off... have you done a 3 way gps speed check?  Perhaps your p/s system isn't working just right.

I grabbed an excel spreadsheet off another forum, but I can't find the source.  I do have the spreadsheet - pm me for a copy.

-de

[Jsavage3]

[carusoam]

Is that artwork for the hangar or the den?

Best regards,

-a-

[gsxrpilot]

13 hours ago, Jsavage3 said:

I'd love to have that in a 6x4 banner for the hangar.

[mike_elliott]

On 10/23/2017 at 11:29 PM, Northern Mooniac said:

Yeah so I’ve heard. Been thinking about taking those vg’s off.... not seeing any benefit really

What is your stall speed? I saw a reduction of 7 kts on a M20V with VG strips. Same wing, results should be similar if installed correctly.

[aviatoreb]

14 minutes ago, gsxrpilot said:

I'd love to have that in a 6x4 banner for the hangar.

That looks like a Porsche style font.

[aviatoreb]

10 minutes ago, mike_elliott said:

What is your stall speed? I saw a reduction of 7 kts on a M20V with VG strips. Same wing, results should be similar if installed correctly.

Mike was that on same airplane before and after install?  Or between two different airplanes?  I ask because I wonder how much variance there may be between airframes.

[mike_elliott]

34 minutes ago, aviatoreb said:

Mike was that on same airplane before and after install?  Or between two different airplanes?  I ask because I wonder how much variance there may be between airframes.

Erik, I didnt stall the plane before the VG's were added, as they were added prior to the owner taking delivery. I stalled the plane at 52 kts about 100 # under gross. I trust the engineering data of the original stall speed was accurate.

 

[aviatoreb]

1 hour ago, mike_elliott said:

Erik, I didnt stall the plane before the VG's were added, as they were added prior to the owner taking delivery. I stalled the plane at 52 kts about 100 # under gross. I trust the engineering data of the original stall speed was accurate.

 

Ah I missed that you were talking about reduction in stall speed.  I thought you were talking reduction of cruise speed.  Any thoughts on that?

vs book speeds I would say my airplane with vgs also stalls about 7 kts below book but it’s also maybe 10+ below book for cruise - but I have vgs Tks and it’s a 231 rocket vs a 252 and no smooth belly either.

[mike_elliott]

1 minute ago, aviatoreb said:

Ah I missed that you were talking about reduction in stall speed.  I thought you were talking reduction of cruise speed.  Any thoughts on that?

vs book speeds I would say my airplane with vgs also stalls about 7 kts below book but it’s also maybe 10+ below book for cruise - but I have vgs Tks and it’s a 231 rocket vs a 252 and no smooth belly either.

No, I dont, Erik. This one also has TKS and I have heard it is about 10kts slower than book by the owner.

[ArtVandelay]

No, I dont, Erik. This one also has TKS and I have heard it is about 10kts slower than book by the owner.

Anytime you put something on the front of an airfoil is going to cause drag, including the landing lights and dirt.From your picture they seem to recess the tks panels which should improve the airflow.

If it’s 10 knots slower I would say that is part tks, part VGs, and the extra antennas that wasn’t on the plane when measuring speed.

I assume if own a nice plane like that you keep it clean.

 

BTW, what’s the strip just in front of the windshield? Seems like that would cause drag.

 

Also, for those that didn’t look closely, the VGs span the entire wing...that’s like drawing a mustache on the Mona Lisa.

 

Tom