r0ckst4r Posted September 27, 2020 Report Posted September 27, 2020 I have noticed that in our POH they give a general take-off configuration of 10 degrees flaps for all take-offs, being regular or short or soft. I am comfortable with this on my usual luxurious paved runways of around 3000 ft and with my massive home base runway of 5000 ft. My question is more of a point of curiosity. Why do they not use a full flaps setting for a short or soft field take-off? When performing a go-around the flaps are already full down at 33 degrees when full power is applied then retracted later. Am I missing something? Quote
donkaye Posted September 28, 2020 Report Posted September 28, 2020 33 minutes ago, r0ckst4r said: I have noticed that in our POH they give a general take-off configuration of 10 degrees flaps for all take-offs, being regular or short or soft. I am comfortable with this on my usual luxurious paved runways of around 3000 ft and with my massive home base runway of 5000 ft. My question is more of a point of curiosity. Why do they not use a full flaps setting for a short or soft field take-off? When performing a go-around the flaps are already full down at 33 degrees when full power is applied then retracted later. Am I missing something? From my mentor instructor, an aeronautical engineer, many years ago. ⅔ as much lift as drag in the approach configuration, ⅔ as much drag as lift in the full flap configuration. 4 Quote
GeeBee Posted September 28, 2020 Report Posted September 28, 2020 It is a compromise. The best second segment climb comes with reduced to zero flaps. The shortest take-off run comes from increased flaps. Example 1. If you have the runway but you need the climb performance, use no flaps and come off the runway with extra speed and energy to quickly achieve Vx. Very commonly we would come off Guatemala City with Flaps 1 "Improved" which means we would accelerate to a higher than normal Vr speed to leave the runway with extra "smash" and reduced drag due to the low flap setting. The climb performance was spectacular but you needed intestinal fortitude to hold the airplane on the deck as the end of the runway came towards you fast. Example 2. Taking off of PHOG nonstop to KATL in a fully loaded 767. OGG was only 7000', same length as LGA. Solution? Roll with the highest flap setting possible other than landing flaps, Flaps 20. Even with a 5 knot tailwind Rwy 2 works better than 20, because 20 has rising terrain, but 2 shoots you out across the beach. over the ocean, no obstacles, so climb performance is not critical, runway performance is the need. Sure she climbs slow, but you got her off the deck quick With light airplanes it is similar but not quite so stark and in a Mooney, you may not have a lot of choices in flap settings, but suffice to say if you need climb performance, the cleaner you leave the ground, the better off you are if you got the runway. If you need to leave the ground quickly, higher flap settings, but be prepared for a slug in the climb due to as donkaye points out, high drag. Consider your climb performance in a aborted landing and that is what you would have at best with a full flap take off. If climb performance is not important, but the runway is really short it would help, but since you have no numbers in the POH you are really in test pilot territory and any mishap would be hard to justify the use of full flaps while sitting at the "big green table" assuming you survive. 4 Quote
r0ckst4r Posted September 28, 2020 Author Report Posted September 28, 2020 58 minutes ago, donkaye said: From my mentor instructor, an aeronautical engineer, many years ago. ⅔ as much lift as drag in the approach configuration, ⅔ as much drag as lift in the full flap configuration. Approach configuration is probably not a good term to use. Do you mean 10 degrees versus 33 degrees? Also I’m still not sure why 33 degrees flaps would not be useful to lift into ground effect earlier for soft field despite the drag. Quote
r0ckst4r Posted September 28, 2020 Author Report Posted September 28, 2020 GeeBee, that’s what I was thinking. A soft field or short runway that just needs you to get off the ground seems like it would call for more flaps but the writers of the POH decided they didn’t want to tread in those waters Quote
StevenL757 Posted September 28, 2020 Report Posted September 28, 2020 15 minutes ago, GeeBee said: Example 2. Taking off of PHOG nonstop to KATL in a fully loaded 767. OGG was only 7000', same length as LGA. Solution? Roll with the highest flap setting possible other than landing flaps, Flaps 20. Even with a 5 knot tailwind Rwy 2 works better than 20, because 20 has rising terrain, but 2 shoots you out across the beach. over the ocean, no obstacles, so climb performance is not critical, runway performance is the need. Sure she climbs slow, but you got her off the deck quick I remember the same takeoff from Kahalui in a United DC-10 before they were retired. The mains were barely off the runway when I saw the opposite end threshold bars flash by, and then a lethargic climb. Quite an experience. Quote
carusoam Posted September 28, 2020 Report Posted September 28, 2020 Rock, You are making great logical strides... But debating the danger in going full flaps... Doesn’t require any logic... If getting into ground effect was the only thing required... sure go full flaps during the T/O... If you decide to climb out... all the extra drag of full flaps begins working against you immediately... Most airplanes are designed to get to a safe altitude... before making configuration changes... The way to do this as quickly as possible, in the shortest distance possible... is to follow your plane’s POH... It’s not like your O had an owners manual written in 1965... If you want to take the discussion to a higher level beyond the POH... there was a great presentation given by another Knowledgable fellow (mr. Kromer) regarding the speed to use during the climb out... To prove this to yourself... get a WAAS device.... connected to your CloudAhoy app... and measure away... (stuff you probably have available to you) Expect that everything in the real world follows the laws of physics really well... If flaps are good... more flaps, doesn’t necessarily behave more gooder... there is real world drag in there that is increasing with the square of your kias... If more flaps was so good... why didn’t we get a 40° setting in our Mooneys? Why don’t they train for full flap T/Os in C152s... Resist doing things... because they sound good... You get extra credit for bringing a great question to discuss... much better than LOP vs. ROP... PP thoughts only, not a CFI... Best regards, -a- 2 1 Quote
carusoam Posted September 28, 2020 Report Posted September 28, 2020 On another topic... I Would think blaming the writers of the POH for not treading in certain waters would be way off base.... Except for one thing... O1 POHs got procedures for soft field T/Os... replete with performance charts... Later Os had these details redacted... as in check your POH and see if you have this data to follow! There could be blame for leaving out an important piece of data, but it wasn’t the writers... What version of the O do you have? Best regards, -a- Quote
r0ckst4r Posted September 28, 2020 Author Report Posted September 28, 2020 I do have the O1 POH and yes I do have the soft field T/O performance chart. All the speeds and configurations are the same just different performance data 1 Quote
r0ckst4r Posted September 28, 2020 Author Report Posted September 28, 2020 Also yes, just to be clear, I do follow the recommended T/O procedures to a "T" but did wonder about the one size fits all take-off configuration in our POH. Quote
kmyfm20s Posted September 28, 2020 Report Posted September 28, 2020 I have inadvertently taken off with full flaps in my screaming eagle and it was an eye opener. The plane literally lifts off the ground and the nose pitches down, I felt like I was going to have a prop strike. If trimmed for a full flaps takeoff the nose down tendency might not be as bad but your air speed is so slow you might not get enough elevator authority. Regardless when it happened I instantly knew what I did and take out a notch of flap immediately. The electric flaps retract slow enough it began to speed up in ground effect and transitioned nicely, everything went to normal. I was off the ground in no time! 1 Quote
carusoam Posted September 28, 2020 Report Posted September 28, 2020 For really fun ideas.... This illustrates what could be done to improve things... But the costs of getting them wrong will have to be paid... The following are incredibly not so safe ideas.... as in they could kill you.... Best acceleration from 0 to T/O speed is done with no flaps at all.... Have the trim set for climb out with full flaps... (you would have to know where that setting is before using it near the ground) With the O, You want to hold the elevator neutral during the run.... so it isn’t dangling and adding drag... Add flaps in time so they are in place right at rotation... some automation or SIC would be nice for this... At VR, climb into ground effect... no more, no less.... One thing for sure... the POH is written for an ordinary pilot to get really good everyday Mooney performance... Sure there are things that the PIC can experiment with... When executed really well... you might save a few feet of T/O run.... Its really cool when you have the tools to collect your own data... Don’t forget to include OAT and DA altitude when discussing the results... A good cold day, can out weigh some really good modified procedures... PP thoughts only, not a performance pilot... Best regards, -a- Quote
kmyfm20s Posted September 28, 2020 Report Posted September 28, 2020 I thought I read somewhere here on MS that @piperpainter set his flaps to match full aileron down deflection to get best short/soft field performance. Of course he had a short body and mechanical flaps so doesn’t necessarily apply to long bodies but it would be interesting to add to @carusoam experiment. 1 Quote
gsxrpilot Posted September 28, 2020 Report Posted September 28, 2020 2 minutes ago, kmyfm20s said: I thought I read somewhere here on MS that @piperpainter set his flaps to match full aileron down deflection to get best short/soft field performance. Of course he had a short body and mechanical flaps so doesn’t necessarily apply to long bodies but it would be interesting to add to @carusoam experiment. I'm pretty sure if you test this... go set your flaps to match full aileron down deflection... you'll notice you're lined up with the take-off flaps mark. Quote
kmyfm20s Posted September 28, 2020 Report Posted September 28, 2020 (edited) 7 minutes ago, gsxrpilot said: I'm pretty sure if you test this... go set your flaps to match full aileron down deflection... you'll notice you're lined up with the take-off flaps mark. Not in my Eagle. Take off flaps are about 2 to 3 inches below no flaps. Full deflection of ailerons are about 2/3 to 3/4 of full flaps. I often wonder why there are not 3 flap position because a middle position would be my favorite when landing light. Edited September 28, 2020 by kmyfm20s 1 Quote
carusoam Posted September 28, 2020 Report Posted September 28, 2020 Then all the POHs would have Hank’s favorite words in them.... Flaps as required... Best regards, -a- Quote
kmyfm20s Posted September 28, 2020 Report Posted September 28, 2020 Maybe my flaps aren’t rigged properly also? Quote
donkaye Posted September 28, 2020 Report Posted September 28, 2020 2 hours ago, r0ckst4r said: Approach configuration is probably not a good term to use. Do you mean 10 degrees versus 33 degrees? Also I’m still not sure why 33 degrees flaps would not be useful to lift into ground effect earlier for soft field despite the drag. The later model Mooneys only have 2 flap settings: 15° and 33°. At takeoff you could say "takeoff flaps"; on landing the same setting would be "approach flaps". The A Model Mooney actually does say to put in full flaps near the end of the takeoff run on a short field takeoff. This won't work on the later model Mooneys with electric flaps. M20A 001.pdf 1 Quote
MooneyMitch Posted September 28, 2020 Report Posted September 28, 2020 My Ovation experience...... and my strong recommendation...... DON’T perform t/o with full flap deflection....... you won’t ever want to do it again!!! 4 Quote
r0ckst4r Posted September 28, 2020 Author Report Posted September 28, 2020 3 hours ago, donkaye said: The later model Mooneys only have 2 flap settings: 15° and 33°. At takeoff you could say "takeoff flaps"; on landing the same setting would be "approach flaps". The A Model Mooney actually does say to put in full flaps near the end of the takeoff run on a short field takeoff. This won't work on the later model Mooneys with electric flaps. M20A 001.pdf 1.3 MB · 1 download Which later model Mooneys? Later model Ovations? Mine is definitely is 10 degrees and 33 degrees. For the sake of clarity the POH does specify a standard "take-off" flaps of 10 degrees but for "approach" it says set to take-off flaps then full flaps below 110 KIAS which I've always found a little confusing. Probably best to refer to the degrees of flaps as those terms don't appear to be standard. Quote
midlifeflyer Posted September 28, 2020 Report Posted September 28, 2020 12 hours ago, r0ckst4r said: When performing a go-around the flaps are already full down at 33 degrees when full power is applied then retracted later It's sequence based on priority in the go-around, Full power applied first is standard for every single-engine airplane I have ever flown. It's necessary to arrest the descent and initiate a (weak) climb. Try retracting flaps and raising gear before adding power on a last second go-around and see what happenes. Better yet, DON'T! ! Retracting flaps from its highest drag configuration to one which enhances the ability to climb out is immediately after, not "later." In most retracts, including the Ovation manual I am looking at, the initial flap adjustment is even before the gear is raised. Quote
mike_elliott Posted September 28, 2020 Report Posted September 28, 2020 10 hours ago, r0ckst4r said: GeeBee, that’s what I was thinking. A soft field or short runway that just needs you to get off the ground seems like it would call for more flaps but the writers of the POH decided they didn’t want to tread in those waters Sometimes legal dept has a way of interpreting factory test pilot notes that doesnt encourage maximum performance 2 Quote
donkaye Posted September 28, 2020 Report Posted September 28, 2020 8 hours ago, r0ckst4r said: Forgot to attach Poorly written in the POH. NO FLAP EXTENSION above 110 Knots. That has been discussed numerous times in the past 20 years. At one point Mooney considered raising the approach flaps airspeed to 140 knots, but testing showed, if I recall correctly, wing torsion issues possibly related to CG position. I don't remember exactly, but I do know it was never implemented. Bottom line to repeat: NO FLAPS ABOVE 110 KNOTS. 1 1 Quote
Hank Posted September 28, 2020 Report Posted September 28, 2020 14 hours ago, carusoam said: Then all the POHs would have Hank’s favorite words in them.... Flaps as required... Best regards, -a- That's what my Owner's Manual says . . . . But my C is a long way from an Ovation . . . . . 1 Quote
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