Re: Lift Reserve Indicator
Posted: Fri Feb 28, 2014 1:58 pm
fastj22 wrote:Here's my test plan. Take off and get at least 3000 AGL. Set my altitude bug to my altitude (virtual field elevation). Start a typical Vy climb simulating a power climb. 300 ft above the bug, pull the power (simulate engine failure) and execute a 180 turn keeping the plane in Vy using the LRI. How did it work? Low or high? Now do it again. This time increasing my turn rate to the point of stall/spin. Eventually spinning it. Repeat until I can just do the 180 turn without spinning. That will tell me the minimum altitude required to execute a 180 turn without an engine and without a spin.
This would be a perfect test with an LRI as well. LRI shouldn't lose any accuracy at higher airspeeds/accelerated turning stalls (though the reference point for the stall may shift.) With an LRI you could do this maneuver, and note the position of the LRI when the stall occurs in the steep-banked turn. Now you have an LRI reference that can tell you just how hard to pull to execute a safe, aggressive turnback.
We practice this maneuver in the PC12 (in the simulator) and use Angle of attack exclusively for the turn, it allows you to pull the maximum available g's for the fastest turnaround time. It usually involves dropping the nose a LOT in order to keep the airspeed up. As soon as the turn is complete, you ride the excess airspeed in a balloon upwards, putting you in a great position to dump the gear/flaps and land. We use a 45 degree bank, although we demonstrated that up to a 60 degree bank can actually get you the best results... but 60 degrees is an unusual maneuver and more likely to screw up. 1000' AGL is our turnaround minimum.
Just remember, if you're executing an aggressive turnback, best-glide speed isn't going to cut it. You need more speed to pull the plane through the steep bank. This means dropping the nose, sometimes by a lot. Once you're level, ride the extra airspeed back to best glide if you need to.