How strong is the M20 wing?

[Shadrach]

Did you read the full narrative on the M20K break up? Mooney said they predicted the onset of flutter at ~240 knots for that airframe. I suspect that 300 mph dive is just an OWT.

Suspect what you want, I believe that the statement was made by Bill Wheat (I believe his signature is in my POH)

There's a huge difference between a test pilot gathering data on an ideal day and terrified XC pilot yanking and pushing through turbulence and or icing conditions.

[Shadrach]

Who suggested that Vne reflected TAS?

Peter for one seemed to when he said:

"If you look at Vne as a limiting speed for flutter then need to look at TAS."

One of bluhighwayflyer also made a post that read like it was implying the same.

[mooniac15u]

Suspect what you want, I believe that the statement was made by Bill Wheat

 

Believe what you want...

[mooniac15u]

Peter for one seemed to when he said:

"If you look at Vne as a limiting speed for flutter then need to look at TAS."

One of bluhighwayflyer also made a post that read like it was implying the same.

 

I think you are finding arguments where none exist.  Everyone is agreeing with you that Vne is IAS and flutter is related to TAS.

[MyNameIsNobody]

After reading all the comments I am trying to interpret what is being said. My understanding from what I have read is that if you are decending and are below VNE...regardless of what ground speed is reading (in smooth air) you are O.K. regarding flutter onset with neutral/reasonable control inputs. EVEN if up high in a turbo...because they designed the airframe considering factors and established the VNE based on airframe remaining intact regardless of groundspeed/altitude up to certified altitude for airframe.

Throw in turbulence or aggressive control inputs and you become a test pilot. Reduce speed get out of yellow. Is this correct?

I descent at full throttle and trim for 500FPM decent in clear air. I will shallow my decent if and when I approach 180MPH indicated. I don't mess around in rough air. I slow down. You are getting beaten up anyway. I NEVER exceed VNE...EVER.

[PTK]

Just to set the record straight, Peter meant what Peter said!

Therefore if anyone has any questions about what Peter meant, all they need to to is go back and reread Peter's posts.

[PTK]

DA is not relevant to Vne for the purposes of this discussion. One can safely descend from 25000 ft to see level within the speed envelope with noting more than an ASI. DA need not be known.

If you're going to look at Vne as a limiting speed for flutter protection and you wish to operate the airplane within its envelope, then you must consider TAS. Therefore DA is very relevant as it pertains to TAS.

That's what Peter said!

[Shadrach]

DA is a relevant parameter to operate the airplane inside its envelope, as it pertains to TAS.

That's what Peter said!

Ok, what TAS numbers define the envelope of your aircraft Peter?

[PTK]

I don't know Ross and I don't care.

I operate a cerificated airplane inside its envelope.

[Shadrach]

bluehighwayflyer implied nothing of the sort, Ross.  bluehighwayflyer simply said that flutter is a function of TAS, which it absolutely is and which you seem to acknowledge.  

 

My reference to turbo drivers alluded to the fact that turbo charged Mooneys and especially big bore turbo charged Mooneys typically experience higher TAS than do their NA counterparts, so their flutter margins, assuming identical airframes, are presumably cut closer.  I, for one, would want to understand all of this before too aggressively pushing the nose over to descend from the M20TN's maximum operating altitude of 25,000 feet at it's maximum (75%) cruise speed of 237 KTAS, for instance.  That was all that I meant to imply.  

 

I spoke not of Vne but agree staying under it should keep all of us safe.

 

Jim

My apologies Jim if I mischaracterized your statement. It was not intentional.

[dlmorris]

I have searched but haven't been able to find data specific to Mooney inflight breakups. I remember some years ago there was mention of the only Mooney breakup was a Missile or Rocket. I don't remember which.

It was a rocket. The tail came off after entering a tstorm and diving to escape it. A close look at the rocket and you'll know why that happened. Don't blame Mooney engineers.

Sent from my SGH-T999L using Tapatalk

[DXB]

Vne varies by model and year. For my 1970 C, Yellow starts at 175 mph, and Vne=200 mph.

Makes me wonder about my '68 with a Vno of 150 and Vne of 189. Vfe/Vfo went from 100 to 125 in '68, but Vno/Vne didn't change to Hank's numbers until '69, with no associated structural change I'm aware of other than the full length rudder. I think Va is the same throughout the C model years. I largely ignore my low Vno (it usually wants to cruise in the 150's) and view 175 as a limit on descent, particularly if it gets a little bumpy. I don't if this is smart or dumb.  

[MyNameIsNobody]

I didn't know the 70's saw a major increase in yellow. My bottom is 150MPH. Interesting. I cruise in yellow ALL THE TIME. 175 or 180, not a big difference. I use 180 as max in decent and pitch to keep below. I use 180 only because it is last clear number before VNE 189.

[Shadrach]

I descend at 195MIAS in smooth air (Vne is 200). What's interesting is that the factory had E's and F's coming off the line together at the same time, sharing identical components and yet same year E model has a Vno 25mph less and a Vne that's 11mph less the F made right next to it.

[AndyFromCB]

It was a rocket. The tail came off after entering a tstorm and diving to escape it. A close look at the rocket and you'll know why that happened. Don't blame Mooney engineers.

Sent from my SGH-T999L using Tapatalk

 

Why did it happen? I took a close look at the Ovation, Bravo and/or Acclaim and they don't look much different than the Rocket. What are you trying to say? Mooney was also categorically opposed to more than 280hp in the long body until of course they bought the STC for 310hp which happens to be the same number as the Rocket. There is nothing wrong with the Rocket and quite frankly there is more talent at Rocket Engineering than there ever was last Mooney other than maybe Al or Roy but those days are long, long gone...

[PTK]

I descend at 195MIAS in smooth air (Vne is 200). What's interesting is that the factory had E's and F's coming off the line together at the same time, sharing identical components and yet same year E model has a Vno 25mph less and a Vne that's 11mph less the F made right next to it.

So hypothetically if you're at say 13000' on an ISO standard day and are flying 195MIAS with a Vne of 200, you're at 241 TAS. 40 MPH above Vne!

[Shadrach]

The Rocket is not a long body, why are you making that comparison? Are you a Rocket owner? I've no experience with them, but I'm told the nose is quite heavy compared to any other Mooney.

[Shadrach]

I think you are finding arguments where none exist.  Everyone is agreeing with you that Vne is IAS and flutter is related to TAS.

See below...

So hypothetically if you're at say 13000' on an ISO standard day and are flying 195MIAS with a Vne of 200, you're at 241 TAS. 40 MPH above Vne.

[Shadrach]

So hypothetically if you're at say 13000' on an ISO standard day and are flying 195MIAS with a Vne of 200, you're at 241 TAS. 40 MPH above Vne!

Ok Peter, I'll bite.

Vne is listed as MIAS for my airframe, so no I would not be 40 MPH above Vne, I'd be 5mph under it.

[PTK]

Red line is IAS and changes with altitude. Vne is TAS and doen't change with altitude. The IAS that yields that TAS, does. Red line IAS decreases with altitude.

(Ross, maybe nit picking here but this is the kind of stuff we don't need to worry about in our certificated aircraft. It's all engineered for us giving us plenty of buffer.)

[Shadrach]

Red line is IAS and changes with altitude. Vne is TAS and doen't change with altitude. The IAS that yields that TAS, does. Red line IAS decreases with altitude.

(Ross, maybe nit picking here but this is the kind of stuff we don't need to worry about in our certificated aircraft. It's all engineered for us giving us plenty of buffer.)

You are mistaken and the documents illustrating said mistake are posted here. I have to assume that you're just trolling at this point.

[PTK]

I don't think so Ross!

But please explain to me your reasoning how you feel I'm mistaken. I consider this a discussion not an argument.

[Shadrach]

I don't think so Ross!

But please explain to me your reasoning how you feel I'm mistaken. I consider this a discussion not an argument.

Per the TCDS, all Vspeeds are in IAS. Reread the thread. It's all been articulated succinctly with screen shots of the TCDS included.

[PTK]

We cannot confuse things and need to take it to a higher level than what's in the POH. In our case Mooney makes it easy for us to glance at the ASI and quickly know our safe limits at any altitude. Without needing to pull our a slide rule.

But in reality Vne is indeed a TAS. The red line we look at is an IAS and limits in the POH may be IAS, but that doesn't change the fact that flutter is dependent on TAS. The IAS red line limit has a built in safety margin that takes into consideration TAS exceeding IAS as altitude increases.

[mooniac15u]

We cannot confuse things and need to take it to a higher level than what's in the POH. In our case Mooney makes it easy for us to glance at the ASI and quockly know our safe limits. Without needing to pull our a slide rule.

But in reality Vne is indeed a TAS. The red line we look at is an IAS and limits in the POH may be IAS, but that doesn't change the fact that flutter is dependent on TAS. The IAS red line limit has a built in safety margin that takes into consideration TAS exceeding IAS as altitude increases.

 

Sorry Peter, but you are wrong about this.  There is a speed not to be exceeded that is related to TAS.  However, Vne is a precisely defined term in aviation.  It is defined by the FAA.  The means of determining it can be found in Part 23 (and the old CAR 3).  It is a marking on the airspeed indicator and as such is legally defined to be IAS per Part 23.