what happens first ?

A

aerosmith

Well-Known Member
Hey - clearly I dont have too much multi time however I was wondering - when doing things in the Seminole like stalls what happens first - buffet, horn or break ? Also in doing the VMC demo the main issue is doing the recovery correctly however how close are you to stall speed when this occurs ?

just thinking about these things - thanks
 
When performing a power off stall, I see the horn sound either just before or at the same time as the buffet. This depends on altitude, temp, CG, etc. We never stall a Seminole to the break. With the power on stall, I almost always hear the horn first.

There are several variables that affect Vmc, and because of this the exact airspeed at which you recover is never the same. Altitude is also a consideration: at low density altitudes, I might expect to lose directional control first while at high density altitudes I expect to hear a stall warning first. Also, some students either level the wings when slowing down or don't apply the 5 degrees bank to begin with, both of which will raise Vmc considerably. But to answer your question, you are extremely close to the stall speed. According to the POH, in the configuration for the Vmc demo stall occurs at 57 while Vmc is 56, thus making Vmc a stalled condition under the specified conditions. (POH page 4-26, someone's going to ask)
 
great explanation paul! you'll usually get the sign to recover a from a vmc demo a few knots above the stall speed. i.e. loss of directional control, horn, buffet. paul is right.about the 2-5 degrees of bank. easy to forget but it's probably one of the most important parts of that manuever. adding bank makes it's difficult to actually vmc the airplane. i remember on one of my training flights doing vmc i had no horn or loss of directional control and i wasn't at the stall speed yet but you could feel the airplane start to rotate. and yes i had the rudder to the floor. i think i could have been in the guiness book of world records for the fastest recovery.
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Great answers. Just wanted to add a point relating to your question.

The main issue for the VMC is getting the throttle off as soon as you lose directional control (no power, no Vmc). It doesn't require much technique. Getting airspeed back and adding throttle back is where practice comes in.

Also, I do Vmc's with as little bank as possible (barely 2 degrees) because the less the bank, the higher the Vmc. Not sure why the FAA want to see the bank when demonstrating Vmc (it's counter to the goal)
 
i don't think the faa wants applicants to "push the envelop" when doing the manuever. nor do the dpe's. it's kind of hard to get the feel for what vmc really is in my opinion in the seminole anyway. or any under powered light twin for that matter. you need to be a lot more careful when you get into something with some power.
 
[ QUOTE ]
i don't think the faa wants applicants to "push the envelop" when doing the manuever. nor do the dpe's. it's kind of hard to get the feel for what vmc really is in my opinion in the seminole anyway. or any under powered light twin for that matter. you need to be a lot more careful when you get into something with some power.

[/ QUOTE ] Removing the bank doesn't "push the envelope". It make it Vmc at a slightly higher speed (like limiting the rudder). It makes the maneuver easier to do, easier to recover, and farther from the stall speed -- which makes it a safer maneuver.
The loss of directional control is the same, and the recover is the same, except you have more rudder authority on the recovery because you have more speed.
Often in training, I'll have the student hold the wings level during Vmc. Once proficient, I'll have them add the 2 degrees of bank like the PTS calls for.

You're right about the power in the Seminole. However, the counter-rotating engines are a big factor in making the plane better mannered during Vmc demos. If you're flying something else, try doing Vmc with the right engine out and see how much better it behaves.
 
what i meant by push the envelop was by not adding the bank, it is possible to actually vmc the airplane. by adding bank, the airplane will stall before it vmc's which is obviously much more desirable. at least that's the way i understood it in training.
 
Actually, for the training, we want the student to see a Vmc. This way they learn to recognize one, and can learn how to recover from it.

I very much avoid stalls during Vmc. If your wing stalls at the same time you have Vmc, you will have your hands full.
STALL + YAW = SPIN (potential)
You don't want to spin a twin. They don't recover like a 172.

(By the way. A two degree bank is almost nothing. It's equivilalent to rasing the left wing tip 6 to 8 inches. Most students tend to bank about 5-7 degrees on their first attempts)
 
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