Overspeed. What is it really?

[MongooseMike]

We've all had this warning before, usually right before we crash and burn! In the prop jobs, it means your aircraft is going too fast. Same with the jets.
But when I first started flying flight sim that I would get an overspeed warning during take off and initial ascent. I certainly wasn't going to fast, under 200knts and under 1000ft. So what is that overspeed? The only thing I can think is that it's the overspeed of the turbine.

[Michael E.]

Vne speed is the Never Exceed speed of the airframe.

Engines don't generally care how fast you fly.

Jets can experience an aerodynamic phenomena called Mach tuck which is too involved to get into in a forum. But generally, it's arerodynamic regime that leads to uncontrollability after exceeding a published speed, usually with a percentage of margin.

Flying through atmosphere creates several kinds of drag on an airframe, some which can be exceeded to the point of uncontrollability or failure. It's up to the manufacturer to determine those values. Unfortunately, if the speed is exceeded, the failure is not often published in the POH, whether aerodynamic or structural. You are expected to operate the aircraft within the published limits to avoid the problem.

Engines have an overspeed factor but you usually monitor that through the EPR or N1 & EGT temp on the engine stack. The POH has what the engine limits are for different flight conditions during take-off and cruise. Those include temperature and density altitude at standard conditions and at altitude. Some include certain equipment conditions aboard the aircraft.

[harleyman52]

Dang...I always thought the jets blared when the flaps were configured wrong for your airspeed to keep the airframe together...

[tatest]

With all damage and warnings turned on, I've seen overspeed warnings at less than Vne, for flaps and gear; in FS2004 these warnings are specific about what is subject to damage.

Propliners particularly have configuration adjustments required at critical speeds during takeoff. I don't fly jets much, but presume most use flaps on takeoff, and there must be a maximum speed for each flap setting, and easy to accelerate through it.

[jwenting]

Dang...I always thought the jets blared when the flaps were configured wrong for your airspeed to keep the airframe together...

some aircraft do that, not all.

[Kurtvw]

We've all had this warning before, usually right before we crash and burn! In the prop jobs, it means your aircraft is going too fast. Same with the jets.
But when I first started flying flight sim that I would get an overspeed warning during take off and initial ascent. I certainly wasn't going to fast, under 200knts and under 1000ft. So what is that overspeed? The only thing I can think is that it's the overspeed of the turbine.

You might also get unexpected warnings using anything other than Indicated speed for reference.

Aircraft V numbers are based on Indicated speed generally. So if you're using any other reference it could be that your Indicated is factually outside the safe range.

However I agree that it seems more likely in your example that the sim was complaining about a flap or gear condition. Did you actually get the 'Overspeed' text message or were you just getting an audio warning, such as a horn or siren?

[MongooseMike]

You might also get unexpected warnings using anything other than Indicated speed for reference.

Aircraft V numbers are based on Indicated speed generally. So if you're using any other reference it could be that your Indicated is factually outside the safe range.

However I agree that it seems more likely in your example that the sim was complaining about a flap or gear condition. Did you actually get the 'Overspeed' text message or were you just getting an audio warning, such as a horn or siren?

I actually got the "overspeed" message and warning lights. The scenario; I'm at between 300 and 600ft, 180-200knts, gear up, flaps extended at 10-15% or more and ascending from the runway. Like I say, this happened to me very consistently when I first started using the flight sim. Certainly not going to fast for the flaps or aircraft. But I did have the engines in the red at around 99-100% which is what I'm assuming was in "overspeed" condition. I finally learned from reading the Learning Center documentation about the proper turbine speed for the aircraft your flying. Since then I haven't experienced the problem.

[alexm]

Sounds like you're on the right track. You want take-off thrust (which does not mean firewalling the throttles) to get off the runway, and also to get to 1,000 agl or so. Then pull back to climb thrust, lower the nose and accelerate to 250kts before pitching to hold speed. Once above transition level, your speed restriction is gone and you can accelerate once again.

[tailwindflyer]

I do not know much about jet engines but with a prop you can easily overspeed the prop if it turns faster than its limit, generally in an attitude that causes the propeller to add a windmilling effect. I would imagine that a jet engine also has limits to it's RPMs where the gyroscopic forces will cause it to break up.

I get these warnings as well and they are usually under Vne and many times on the low end of Vno in jet aircraft and rarely when I fly a propeller aircraft.

Mike

[ascot2054]

In real life going through VNE can lead to wing failure...!!
then

Big crash n burn