I think when Peter gets done with = his, it’s gonna be around mach 2 (give or take)

Kevin

From: = Lancair Mailing List = [mailto:lml@lancaironline.net] On Behalf Of Douglas Brunner
Sent: Tuesday, December = 08, 2009 8:14 PM
To: lml
Subject: [LML] Re: Vne = discussion

Any idea of the Maximum Mach for a Legacy?

-----Original Message-----
From: Frederick Moreno
Sent: Dec 8, 2009 11:16 AM
To: lml
Subject: [LML] Vne discussion

“Can someone give the = criteria and procedure that is used to derive a Vne speed = ?”

There are lots of issues = affecting Vne as noted in previous posts.

But as I recall there is one = test requirement for FAR 23 certified aircraft: Whatever the = manufacturer sets for Vne ( which setting could arise from many = factors), the aircraft must be flight tested to 1.1 times Vne (sometimes = called Vd for dive speed) successfully before it can be = certificated.

So an aircraft may be able to = fly, say, 1.2 times Vne before something terrible happens, but only the = territory up to 1.1 times Vne is explored in the certification = test.

Thus flying beyond this speed = would suggest serious test flying as you are well and truly in = unexplored territory, and best have helmet and parachute on. =

Whether or not a stick or = rudder rap is required at 1.1 times Vne, I do not know. Perhaps = someone closer to the current version of FAR 23 can confirm or deny this = requirement. In any event, a stick rap at 1.1 times Vne would be = require lots of preparation and some enlarged cojones. Not = recommended.

When Brent Regan and I were = racing his Lancair IV Denver to Oshkosh (1996, 97 as I recall), the = descent profile was Mach limited initially starting at 27,000 feet using = a hard limit of Mach 0.58. This was chosen because the factory = aircraft was test flown to Mach 0.6 and we did not want to enter the = unknown. This Mach number (I had to compute it in those early days = – no Mach displays then) was held until the IAS built to Vne (274 = knots IAS) and this IAS was held to the bottom of descent, all occurring = at 90-100% power. The maximum cruise speed at 27,000 was about 320 = knots TAS (corrected for temperature and compressibility effects) and = Mach 0.52. As I recall, it only required 200-300 feet per minute initial = descent at the high power setting to drive the Mach number up to 0.58, = so the descent started out very flat, and the built up as the air got = thicker. I think we hit Vne at about 12-14,000 feet and the = maximum descent rate near the bottom of descent was off scale on the = VSI. It sounded quite different from cruise and caused the hair on = the back of the neck to stand up a bit particularly since much of the = descent was in IMC.

Key point for you IVP guys: = It does not take much nose down high altitudes and high power settings = to push you up to Mmo, the maximum allowable Mach number.

Y’all be careful out = there.

Fred

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