Calling all MEIs

B767Driver · May 7th, 2006, 19:22

In the Vmc discussion in multi engine training...do you teach that indicated stall speed increases with altitude or remains constant with altitude?

I see a lot of instructional notes that teach that the indicated stall speed increases. At speeds below 200 kias shouldn't it be taught that indicated stall speed is constant?

FlyingNole · May 7th, 2006, 19:45

Its not...Vmc is reduced with altitude.

FlyinTim · May 7th, 2006, 21:59

I teach that Stall speed remains constant... and VMC decreases with altitude.

He was talking about Critical Density altitude... where VMC and stall speed meet = BAD day.

FOD · May 7th, 2006, 23:28

calibrated/indicated stall speed should stay the same with an increase in altitude. True airspeed will be what will change.

jtrain609 · May 8th, 2006, 08:41

VMC and stall speed are pretty much the same number on a Piper Seminole, what's the problem?

SteveC · May 8th, 2006, 09:41

Quote:

Originally Posted by John Herreshoff

VMC and stall speed are pretty much the same number on a Piper Seminole, what's the problem?

I bet it's only a big oops if the pilot lets it get completely away while stalling and losing directional control all at the same time. Uh-Oh, cheerios! Time to play spin the twin!

jtrain609 · May 8th, 2006, 12:19

True, but if you stall BEFORE you reach VMC then VMC isn't an issue. I.E. With the Seminole, stall speed with flaps is 55, VMC is 56 and stall speed without flaps is 57. Realistically also the engines are probably not developing a full 180 HP and your CG is further forward than the after legal CG, so you'll probably stall before you lose directional control eh?

FlyingNole · May 8th, 2006, 13:58

Thats why with the Demo I show my students both ways. Loss of directional control, and to the stall/buffet/break. Also because some DEs down here wanna see both ways and that you understand why.

Just hold aeilerons neutral for the loss of control, and no explanation needed for the break/stall.

E_Dawg · May 8th, 2006, 15:58

I would not want to demo a buffet, stall, break on one engine (if that's what you meant).

FlyingNole · May 8th, 2006, 19:06

you do Vmc with criticle engine throttle at idle power. There is no problem doing it to the buffet as long as your feet are on the pedals to make sure the student doesnt slam the wrong rudder in. Its a gradual maneuver anyway, so its not like you're throwing the bird into a crazy situation in a short time.

jtrain609 · May 8th, 2006, 20:57

I don't trust students. One tried to turn off the wrong set of mags on me before.

FlyingNole · May 8th, 2006, 22:35

Thats why I just have them touch it, and say something to the affect of "Left Engine, Mags to off" and touch it, this way they cant mess up....Or supposed to not mess up.

jtrain609 · May 8th, 2006, 23:49

I have them shut the mags off and do a full shutdown and secure when we do an actual engine shutdown/feather. I just want them to be real, real, real specific about what they're doing. I had him say left but reach for the right. I jumped on his ass as he was reaching for the wrong ones (I'm still a pretty paranoid CFI)

meritflyer · May 9th, 2006, 18:33

"True, but if you stall BEFORE you reach VMC then VMC isn't an issue. I.E. With the Seminole, stall speed with flaps is 55, VMC is 56 and stall speed without flaps is 57. Realistically also the engines are probably not developing a full 180 HP and your CG is further forward than the after legal CG, so you'll probably stall before you lose directional control eh?"

Because Vmc and stall are relatively close in the Seminole, I would definately consider Vmc to still be an issue. But I can see your point. If you were at alitiude, less engine power, average weight, and forward CG you'd definately see a decrease in Vmc which would result in a stall before Vmc. Vmc is a Seminole is no big deal. I have flown with it right at Vmc and its like a wounded duck flying in a circle.

Matt777 · May 23rd, 2006, 04:55

Quote:

Originally Posted by FlyingNole

you do Vmc with criticle engine throttle at idle power. There is no problem doing it to the buffet as long as your feet are on the pedals to make sure the student doesnt slam the wrong rudder in. Its a gradual maneuver anyway, so its not like you're throwing the bird into a crazy situation in a short time.

What if lower than standard temperature (or low density altitude) causes Vmc to be reached a nanosecond after you feel that buffet? .... so that you hit Vmc just as you are about to begin dropping the nose?

Well... now that I think about it more, as long as you retard the Vmc handle (throttle of operating engine) you are instantly reducing Vmc so that you are no longer at Vmc- even if this did happen. So then you are just a glider that happens to have two engines at idle... making Vmc a non-issue. Interesting. But I still am too scared to try it!

Also, in response to the other poster, loss of directional control can definitely be reached in a seminole at below standard temperatures (I'm up in Washington State and flew a Vmc demo here back in March)... here's what I thought during the maneuver, " No stall horn or buffet yet, but it seems that I can't quite hold heading anymore and I have the rudder full down... time to recover".

May 7th, 2006, 19:22	#1
B767Driver Old Skool Join Date: Sep 2003 Posts: 1,859	Calling all MEIs In the Vmc discussion in multi engine training...do you teach that indicated stall speed increases with altitude or remains constant with altitude? I see a lot of instructional notes that teach that the indicated stall speed increases. At speeds below 200 kias shouldn't it be taught that indicated stall speed is constant?

May 7th, 2006, 19:45	#2
FlyingNole Old Skool Join Date: Mar 2004 Location: Ft. Lauderdale Posts: 2,090	Re: Calling all MEIs Its not...Vmc is reduced with altitude. __________________ Don't call her a babe, ok? She is a Chechnyan prostitute, and you will address her as such! -ATHF

May 7th, 2006, 21:59	#3
FlyinTim Junior Member Join Date: Mar 2006 Location: Boston, MA Posts: 46	Re: Calling all MEIs I teach that Stall speed remains constant... and VMC decreases with altitude. He was talking about Critical Density altitude... where VMC and stall speed meet = BAD day.

May 7th, 2006, 23:28	#4
FOD Junior Member Join Date: Apr 2003 Posts: 213	Re: Calling all MEIs calibrated/indicated stall speed should stay the same with an increase in altitude. True airspeed will be what will change.

May 8th, 2006, 08:41	#5
jtrain609 Old Skool Join Date: Feb 2002 Location: Park City, UT Posts: 12,321	Re: Calling all MEIs VMC and stall speed are pretty much the same number on a Piper Seminole, what's the problem? __________________

May 8th, 2006, 12:19	#7
jtrain609 Old Skool Join Date: Feb 2002 Location: Park City, UT Posts: 12,321	Re: Calling all MEIs True, but if you stall BEFORE you reach VMC then VMC isn't an issue. I.E. With the Seminole, stall speed with flaps is 55, VMC is 56 and stall speed without flaps is 57. Realistically also the engines are probably not developing a full 180 HP and your CG is further forward than the after legal CG, so you'll probably stall before you lose directional control eh? __________________

May 8th, 2006, 13:58	#8
FlyingNole Old Skool Join Date: Mar 2004 Location: Ft. Lauderdale Posts: 2,090	Re: Calling all MEIs Thats why with the Demo I show my students both ways. Loss of directional control, and to the stall/buffet/break. Also because some DEs down here wanna see both ways and that you understand why. Just hold aeilerons neutral for the loss of control, and no explanation needed for the break/stall. __________________ Don't call her a babe, ok? She is a Chechnyan prostitute, and you will address her as such! -ATHF

May 8th, 2006, 15:58	#9
E_Dawg Moderator Join Date: Apr 2002 Location: chicago Posts: 4,170	Re: Calling all MEIs I would not want to demo a buffet, stall, break on one engine (if that's what you meant). __________________ Yeah, I just stare at my desk; but it looks like I'm working. I do that for probably another hour after lunch, too. I'd say in a given week I probably only do about fifteen minutes of real, actual, work.

May 8th, 2006, 19:06	#10
FlyingNole Old Skool Join Date: Mar 2004 Location: Ft. Lauderdale Posts: 2,090	Re: Calling all MEIs you do Vmc with criticle engine throttle at idle power. There is no problem doing it to the buffet as long as your feet are on the pedals to make sure the student doesnt slam the wrong rudder in. Its a gradual maneuver anyway, so its not like you're throwing the bird into a crazy situation in a short time. __________________ Don't call her a babe, ok? She is a Chechnyan prostitute, and you will address her as such! -ATHF

May 8th, 2006, 20:57	#11
jtrain609 Old Skool Join Date: Feb 2002 Location: Park City, UT Posts: 12,321	Re: Calling all MEIs I don't trust students. One tried to turn off the wrong set of mags on me before. __________________

May 8th, 2006, 22:35	#12
FlyingNole Old Skool Join Date: Mar 2004 Location: Ft. Lauderdale Posts: 2,090	Re: Calling all MEIs Thats why I just have them touch it, and say something to the affect of "Left Engine, Mags to off" and touch it, this way they cant mess up....Or supposed to not mess up. __________________ Don't call her a babe, ok? She is a Chechnyan prostitute, and you will address her as such! -ATHF

May 8th, 2006, 23:49	#13
jtrain609 Old Skool Join Date: Feb 2002 Location: Park City, UT Posts: 12,321	Re: Calling all MEIs I have them shut the mags off and do a full shutdown and secure when we do an actual engine shutdown/feather. I just want them to be real, real, real specific about what they're doing. I had him say left but reach for the right. I jumped on his ass as he was reaching for the wrong ones (I'm still a pretty paranoid CFI) __________________

May 9th, 2006, 18:33	#14
meritflyer Old Skool Join Date: Dec 2005 Location: Winchestertonfieldville Posts: 6,608	Re: Calling all MEIs "True, but if you stall BEFORE you reach VMC then VMC isn't an issue. I.E. With the Seminole, stall speed with flaps is 55, VMC is 56 and stall speed without flaps is 57. Realistically also the engines are probably not developing a full 180 HP and your CG is further forward than the after legal CG, so you'll probably stall before you lose directional control eh?" Because Vmc and stall are relatively close in the Seminole, I would definately consider Vmc to still be an issue. But I can see your point. If you were at alitiude, less engine power, average weight, and forward CG you'd definately see a decrease in Vmc which would result in a stall before Vmc. Vmc is a Seminole is no big deal. I have flown with it right at Vmc and its like a wounded duck flying in a circle. __________________ The simplest answer tends to be correct.

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