Piloto Posted May 24, 2016 Report Posted May 24, 2016 The Spirit of St. Louis total fueled weight was 5000 pounds with a 220HP engine. With a 220HP the most it could lift was 6,600 pounds (level flight at sea level). Out of ground effect and thermals it takes 1HP to levitate 33 pounds. In planes you need the excess power to climb and turn. That is why you increase power when doing 60deg bank 2G turns. José
carusoam Posted May 24, 2016 Report Posted May 24, 2016 1) There isn't a pilot good enough to turn back time... 2) the stall horn would work as usual. 3) But, if you can't lower the nose enough to turn it off, flying in ground effect would be your next best choice. 4) The problems associated with flying in ground effect, farm equipment and trees. 5) knowing how to calculate Density Altitude is very helpful. Compare how it effects the plane's ability to get off the ground and climb. 6) Let's say we had an AOA installed and calibrated prior to loading up the plane and performing a T/O. - We generate maximum power. FF and MP are at book values. - We hold the nose on the ground as long as possible. The T/O run is extremely long - Altitude is increasing at an incredibly slow rate, lower the nose to gain speed to Vy - Going towards Vy, but the altitude starts to decrease... Balance AOA with airspeed. Try to milk out a positive climb rate. Each time AOA is increased the airspeed starts to decrease. - The subtle nature of the situation starts to seep in... lift costs drag. Lift is neccesary to maintain altitude. Excess power is needed to climb. - How much extra power is there? - If we don't have enough extra power to climb at Vy, we have started a bad situation. - your altitude indicator is telling you to climb. Your air speed indicator is telling you to speed up to Vy. You abide by the AOA and lower the nose, thus descending towards the ground... - turning towards the airport also causes additional drag. - the more you bank, the more lift you lose. The faster you descend. - High DA decreases performance. Lower power available from the engine and less lift available from the wings. - increasing AOA increases lift and drag. High AOA is a very high drag situation. - The lessons learned: it takes a fair amount of excess power to fly around with Marauder's Ladies. - The examples given of the three different Mooneys were not flights that ended in stalls. One ended in trees, another collided with agricultural equipment used to water farmland. I don't recall where the off-airport landing of the M20C five ended up... Can you generate your own performance numbers? (If not use the POH for this) - T/O distance and climb rate are great ways of measuring this critical info... - Collect data using an app like CloudAhoy. It measures T/O distance and records vertical speed. - Plan a few flights in the legal regime of your plane using your POH... - 500 # below MGTW (or landing weight if different) - 300 # below - 100 # below - At MGTW Plot weight vs T/O run in feet. Compare to POH data Plot weight vs climb rate in fpm. Compare to POH data You will find that there is not a straight line that connects all your data. As you add weight... the T/O run increases non-linearly and climb rate drops off similarly. A curve fitting mathematician could help you define what the rest of the curve looks like on the overweight end of the graph without having to actually go there. Adding more useful power is a method of increasing the comfort level of take off at short fields... a similar legal experiment could be run using power as a variable. plot T/O distance vs MP or RPM or %hp. Collect climb rate data at Vy as you pass through 1,000', 2,000’, 3,000'.... The important part of this run-on sentence is... Don't run out of excess power. If you run-out near the ground, a landing is in your near future... Make the best of it. Get slow... PP thoughts. Shared because I have run out of excess power once. (Stuck valve on departure) Best regard, -a-
ArtVandelay Posted May 24, 2016 Report Posted May 24, 2016 The J got a 160lb increase, so there is more than just horsepower to consider
carusoam Posted May 24, 2016 Report Posted May 24, 2016 Weight, weather and HP.... Lots of variables in the equation. Legal increases to MGTW are nice. Legal = pretty well proven and documented. In Mooney history, increases to MGTW have included stronger landing gear, changes to the tail feathers, wing tip updates(?), and more power. Carrying higher weights includes needing more AOA. To increase AOA, the tail needs to pull down more. When the tail pulls down more, there is increased drag. The high AOA comes with increased drag as well. Mooneys show their best performances with cold, dry air at sea level. Lightly weighted and balanced towards the back of the envelope... PP knowledge, not CFI level of thinking... Best regards, -a- -a-
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