Topic changed so I changed the subject.

 

Generally, a Lancair 320 equipped with a 360 can easily push "cruise" into the yellow arc (> 180 KIAS) and stay there all day..  But to the point, I want to know how many have slowed their 320/360 to Va (143 KIAS) in turbulence?  Come on, raise your hands if you do that.... OK, I only see 2 or 3 hands.

 

I have difficulty slowing down to 143 KIAS and I would use a few degrees of flaps to keep the nose down.  I have slowed in nasty turbulence - to about 160 KIAS from 180.  For me, nasty is my guess of moderate turbulence as evaluated in a 320. 

 

So, for those of us frequently flying in the yellow arc and not slowing to Va in turbulence, how are we different than Stuart's controlled expansion of the flight envelope beyond Vne?  OK, that is from a structural aspect, not control surface flutter.

 

Well, let's see.  Below Va is the speed at which no combination of maneuver and gust load (<30 fps) at max gross weight cannot produce a positive air load that would create damage.

 

Va can be computed as Vs * SQRT(Limit load factor)

 

As originally set up, the stated limit was 4.5 Gs at 1685 pounds.  And let's say we use 68 KIAS as cruise configuration Vs (stall speed).

 

Then Va = 68* SQRT (4.5) = 68* 2.1 = 142.8 KIAS

 

 

Grayhawk

 

 

 

In a message dated 12/20/2009 6:35:13 P.M. Central Standard Time, sltroutman@hotmail.com writes:

It would seem to me that the maneuvering speed would be more of a concern than VNE but no mention of it yet. I bet that most have exceeded Va and never thought twice about it ??

----- Original Message -----

From: farnsworth

To: lml@lancaironline.net

Sent: Sunday, December 20, 2009 6:51 AM

Subject: [LML] Re: Tone on list

 

 

“On August 09, 2005 N750F, a Lancair IV-P disintegrated in flight in a dive at Mach 0.62. It is not in your list as it happened in Canada (Transport Canada Report A05W0160).

In June of 2003 N29ME, a Lancair IV-P, disintegrated in flight after exceeding 253KTAS (274KIAS). (NTSB Report ATL03LA094)”

It appears that both accident aircraft were being flow in thunderstorms at the time they disintegrated.

Do you suppose that the turbulence associated with thunderstorms may have been a factor in these in-flight breakups?

Just wondering.

 

Lynn Farnsworth