Vortex Generators for M 20 C

[Oscar Avalle]

I have been looking at installing Vortex Generators on my M 20 C. My field is at 5000 feet altitude.  I read that while these improve climb and take off performance, they also may have an impact on cruise speed.  I was wondering if somebody had had experience with this mod and if it is something worth doing.

Thanks

Oscar

[WardHolbrook]

Quote: oavalle

I have been looking at installing Vortex Generators on my M 20 C. My field is at 5000 feet altitude.  I read that while these improve climb and take off performance, they also may have an impact on cruise speed.  I was wondering if somebody had had experience with this mod and if it is something worth doing.

Thanks

Oscar

[Lood]

I was under the impression that the main benefits of VG's are that they lower the stall speed and provide more effective control at lower airspeeds, instead. Theoretically, you should be able to rotate at a lower airspeed which might cut a bit off the take off run. However, one of the things that Mooney wings don't like, is flying at low speed.

[aviatoreb]

Quote: Lood

I was under the impression that the main benefits of VG's are that they lower the stall speed and provide more effective control at lower airspeeds, instead. Theoretically, you should be able to rotate at a lower airspeed which might cut a bit off the take off run. However, one of the things that Mooney wings don't like, is flying at low speed.

[Piloto]

My hangar neighbor had them installed on his Baron. But had them removed after his 5yr old grandaugther was cut on her thighs while helping granpa washing the plane. He said they were not worth it.

José 

[jetdriven]

If you read enough, VG's lower stall speed by a few knots.  But when you stall it (and it will), the warning is less and the airflow separation is much more suddent and complete. If this happens near the ground, well, you know. 

 

[aviatoreb]

Quote: jetdriven

If you read enough, VG's lower stall speed by a few knots.  But when you stall it (and it will), the warning is less and the airflow separation is much more suddent and complete. If this happens near the ground, well, you know. 

 

[jetdriven]

Did you notice a loss in cruise speed?  Rumor is 3-5 KTAS.  I would think so, seeing how the Mooney wing is laminar flow.

[Bennett]

I do not have vortex generators on my Mooney, not do I ever plan to install them.  I did have them on my Cessna 120, and they did work exactly as advertised - shorter take-offs, (and landings), lower stall speed, better aileron control approaching a stall, and they did cost a few knots, which in a Cessna 120 doesn't mean very much. I do not want to give up any speed on my M20J, and I don't fly into the very short strips that I did with the Cessna 120.  I have seen a few Mooneys with them, and I always have wanted to ask about the owner's experiences. The installation itself is not difficult - the kit come with templates with cut-outs for the VGs, which are glued to the wings, horizontal stabilizer, and vertical stabilizer. Can be a bit messy, and the VGs should be painted before gluing them down. 

[aviatoreb]

Quote: jetdriven

Did you notice a loss in cruise speed?  Rumor is 3-5 KTAS.  I would think so, seeing how the Mooney wing is laminar flow.

[richardheitzman]

I see you painting yourself into as box that you will not be able to get out of. The original design of that wing and the flight performance especially TO and Landing is a critical design. If you are hot, heavy and high, and your aircraft charts do not show you capable of taking off with the available runway in front of you, PLUS a added 50% margin of safety, then dont launch. If you are having performance issues with the M20C why dont you move into a M20J or at least a M20E. The fuel injected engine and increased horsepower is what you need. Not some perceived performance enhancements of VG's. Better yet, find you a M20F with a turbo and really see a increased margin of Safety. TO and Landings are the leading cause of injury and death in aircraft accidents. So be carefull PLEASE!

[Oscar Avalle]

Thank you for all your valuable comments and suggestions... unfortunately at this point upgrade to an M 20 E or J is not an option...

 

Oscar

[jetdriven]

Oscar, what is your leaning technique? Takeoff technique?  Field length? Obstructions?

[aviatoreb]

Quote: aviatoreb

No I do not see any FURTHER loss in cruise speed - but let me qualify - as I said my rocket seems to be 5-8kts slower than book but I have a TKS install dating to 1994 and it is a bit rougher than the latest TKS installs I have seen.  I have read that TKS can rob you 5-10 kts if the install is not smooth on a Mooney and I can confirm that.  I do not notice any further loss of speed due to the VGs.  But if I am loosing speed due to the TKS then the flow is already tripped and then it can be argued that it is more likely that the VGs reside inside the boundary layer than in a clean Mooney wing without TKS where the boundary layer is more likely thinner.  So I would not be surprised if VGs rob me of no further speed, or at least minimal further penalty, but they may rob a clean Mooney of a few kts.

I had them installed shortly after I first started flying this Mooney just over a year ago and I noticed no speed difference after the install but I was not carefully book keeping at that stage yet.  General impression was that cruise seemed pretty much before as after install.  The slow speed crisp handling benefits thought were pronounced.

[Oscar Avalle]

Thank you for asking about my technique. To be frank, until about three month ago I was a low land flyier, Washington DC area... So 4000 and 6000 feet were my normal cruising altitudes... Now I moved to Guatemala City, were the airport is at 5000 feet, with a 9800 feef long runway.

Thus I have to consider many other aspect much more seriously than I did before. For example density altitude, leaning before take off... etc. So whatever recommendation somebody on the list may have for me to get used to this new universe will be more than welcomed... (short of selling N9341V...)

 

Oscaar

[M016576]

Quote: oavalle

Thank you for asking about my technique. To be frank, until about three month ago I was a low land flyier, Washington DC area... So 4000 and 6000 feet were my normal cruising altitudes... Now I moved to Guatemala City, were the airport is at 5000 feet, with a 9800 feef long runway.

Thus I have to consider many other aspect much more seriously than I did before. For example density altitude, leaning before take off... etc. So whatever recommendation somebody on the list may have for me to get used to this new universe will be more than welcomed... (short of selling N9341V...)

 

Oscaar

[jetdriven]

Quote: oavalle

Thank you for asking about my technique. To be frank, until about three month ago I was a low land flyier, Washington DC area... So 4000 and 6000 feet were my normal cruising altitudes... Now I moved to Guatemala City, were the airport is at 5000 feet, with a 9800 feef long runway.

Thus I have to consider many other aspect much more seriously than I did before. For example density altitude, leaning before take off... etc. So whatever recommendation somebody on the list may have for me to get used to this new universe will be more than welcomed... (short of selling N9341V...)

 

Oscaar

[Lood]

If you have an engine analyzer, the target EGT for take off is normally around 1250 deg. My runway is at 4000' and I seldom need more than 1500' for any take off - even when fully loaded.

[Oscar Avalle]

Thank you will do so!

[KSMooniac]

Go here: http://advancedpilot.com/tech.html and read the "Target EGT" method for takeoff and climb leaning... it is simple, and efficient.

[jetdriven]

Scott, if he is at 8K density altitude, he can probably go 50-100 degrees higher than target. We do.