EB29R Flutter speed

[Kailee71]

Hi all,

I'm just noticing that the EB29R seems to flutter at slower IAS at higher altitudes than at lower altitudes. At 3000m+ it'll start to flutter as low as 240kmh indicated, which means Vne is not even reachable... Lower down I can easily reach 250+ kph. This is with full water. Is this intended/expected behaviour? I hadn't noticed this in other planes...

Also - is there a reason why this plane doesn't have a artificial horizon? Long wings too fragile in clouds?

Many many thnx for the excellent plane though!

Kailee.

[wickid]

The flutterspeed of a plane depends on the TAS (true air speed). IAS (indicated airspeed, what you see on you airspeed indicator) decreases for a given TAS when the altitude increases.

So at sea level:
Vne is 270 kph TAS, which is 270 kph IAS in a standard atmosphere.

At 3000 meters:
Vne is still 270 TAS, but your IAS will be around 240 kph (IAS decreases by approximately 1 kph per 100 meters altitude at a constant TAS)

So your experience is completely correct and expected. It is the same on all planes. There is some randomness in the exact speed flutter starts.

[Kailee71]

OMG good to learn this in the safety of a comfy chair with a cup of tea next to me . Thanks for the quick reply - so wave flying quickly reduces your flight envelope then?


Kailee.

[BHudson]

That's correct, most gliders will have a placard in the cockpit with maximum indicated airspeeds for different altitudes. It will also be listed in the manual. You can see actually read them in some Condor gliders (like the Ventus) if you have VR or a head tracker!

[congo]

Also - is there a reason why this plane doesn't have a artificial horizon?
Kailee.

Well, mine does.

[janjansen]

so wave flying quickly reduces your flight envelope then?

Yep. Stall speed goes up, VNE goes down (at least when you consider indicated air speed). Theoretically (for a glider), at some altitude the two meet and your minimum and maximum speeds become the same. This is actually what determines the aerodynamic ceiling for planes and is called Coffin corner. The U2 spy plane would have only a few knots margin between stalling and overspeeding