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pre-68 short body VNo/VNe

Ashe

By Ashe
in Vintage Mooneys (pre-J models)

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Ashe Contributor

Ashe

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I'm currently shopping older Mooneys.  From reading a few articles and the forums hear, I understand that the pre-1969 M20 C and E models had lower VNO & VNE than later yearss (as well as all long-bodied M20's).  However, with the '65-'67 M20E being the hot rod darling that it is, it seems to me that a nicely modded mid '60s E-model wouldn't have much trouble busting the 189mph VNE in level flight at full power.  From what I've read, there may be a couple very heavily modded C's that might do this, too.


I've read that the V-speed change in 1969 was merely a paperwork affair, and that the '65-'68 short bodies are just as structurally strong as the 1969-1978's are.  Do owners of more highly modded mid-60s birds just get comfortable flying into the yellow and occasionally above redline?  Is there an STC that officially can change this...perhaps allowing a later model ASI installation?

Ashe

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Gone Grand Master

Gone

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Ashe:



I own a 65 E model and I fly in the yellow arc all the time. 



I heard that the 189 mph VNE was based on the fact that the FAA inspector did not want the test pilot to go any faster than that speed during the certification flight (process??) and that is where it was marked.  Not certain about the veracity of that story, but it is a cool story.

The other story is that the engineers ran the tests and they figured out the flutter conditions and set the VNE somewhat below that speed.  In later models some changes were made to some parts of the structure which modified the expected flutter conditions, upping the VNE. Again, not certain about the veracity but it is a cool story too.


I have had mine cross VNE twice in level flight near 5500' at WOT and 2500 RPM, before I caught it and pulled the MP back a little.  During 500 fpm descents in calm conditions, I am pulling about 20 inches MP and the airspeed indicator shows between 175 and 180 mph - indicated, not true airspeed.


I am not certain I would cross VNE on purpose - just not wanting to push things, but my airframe can easily approach VNE in level flight at given altitudes.  If I had the financial wherewithall, I would mod like stink (including the Lopresti cowl etc) and it would be even easier to do.


Remember, we are Mooney drivers.   Speed is not an important consideration for us - it is the ONLY consideration Wink


OK, maybe not, but going fast does give us bragging rights....


 

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Comatose Collaborator

Comatose

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My modified 66 C model cruises in the low yellow arc at about 155mph indicated at 6k or so. You get used to it. Its really more of a problem descending than it is in level flight because you'll typically be higher on a flight where you need that extra bit of speed. Flying higher also gets you above the bumps where you'd want to be in the green anyway. Descending takes some advanced planning. As long as it isn't excessively bumpy I just try to keep it below 170mph indicated on the way down. No particularly scientific reason for that, but I like to leave a little margin. Redline is redline as far as I'm concerned.


As neat as the mooney speed is, its really not much of an advantage for a 15 minute hop between airports, so why firewall the throttle and suck down gas at low altitudes?


What you'll really get tired of fast is the 100mph flap extension speed. That's also a much more "real" issue in that you can get cracks your rear spar if you routinely overspeed it.


 


 


 


 

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Hank Grand Master

Hank

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I've heard some people complain of their low 105 mph flap speed. My 70-model flap speed is 125, and gear is 120 mph. When transitioning from my training aircraft, a large part of  my transition time was spent learning how to slow down to pattern speed; I still often drop initial flaps while rolling into the downwind, decelerating through 120 heading towards 90 mph.


Mooneys of all models and years are slippery little buggers, and just pulling the throttle back will do very little to change your speed. Pull the throttle, watch the altimeter, inch the yoke back, and finally the airspeed needle starts to crawl. It can take some distance to slow from descent [~160 mph] down to flap speed . . .

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Hank Grand Master

Hank

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I've had to do 360's to get into our uncontrolled field just because the nearby Class D controller wouldn't let me descend below 4000 msl until less than 4 nm away. That just won't do--1000 feet per mile is an ungodly foot-per-minute rate, and great for acceleration! So I swing wide to the right, do a 360 and head back in. OK, maybe it's just a 320, but it lets me get down and get slow.

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