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Flaps to aid climbing - truth or fiction


Ed Cesnalis

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I prefer clearing takeoff altitude in a shorter distance vs time. I may get to 500' faster in time in zero flaps, but I'm way out off the end of the runway and too low at the end of the runway to turn. I couldn't make it back in the 180 turn plus I'm in zero flaps and would prefer 15 in an emergency.  In 15 all I have to do is lower the nose, turn and concentrate on landing and not worry about adding landing flaps or trying to slow down or being closer to stall speed. I prefer a steeper shorter easier to recover climb to 500' and less complex in an emergency. Using 15 flaps also allows me good altitude halfway down the runway with ample time to lower the nose and land at a relatively slow speed and usually well above stall. 15 flaps has me off the runway sooner, gets altitude quicker in a shorter distance and all I have to do if the engine quits is lower the nose and with 15 flaps and  I'll have better speed above stall to save my butt. I see no redeeming qualities to takeoff in zero flaps unless I just want to race someone out off the end of the runway or just past.

 

You're right zero gets you there faster, but 15 gets you there in a shorter distance and closer to the end of the runway. 

 

For me, using 15 flaps is setting yourself up for an easier successful emergency resolution if one pops up out of the blue and zero flaps by the end of the runway leaves me no options other than the mesquite trees at the end.

 

 

Here is the other variable which none are mentioning. Weight at takeoff. If you are solo and 175 lbs things are good in either flap setting. If you are two up and close to max weight or more then zero flaps becomes a handicap over 15. 

No one here has mentioned prop pitch for takeoff help or hinderance.

 

So some or many of our comparable numbers aren't really that comparable. Then some of these comparisons become apples and oranges. I fly fairly heavy all the time where many here are fairly light in comparison. The heavy aircraft flying at gross weight+ with a high DA is handicapped at zero over 15.

 

Comparing a flight like I did the other day close to 1420 vs maybe Andy at solo (I think he's around 180) will have very different results. Takeoff rolls at max weight, in zero flaps with a high DA carries with it a lot of speed to get off the ground and keeps you in a shallow climb.

 

I prefer altitude first and speed second. With enough altitude I can get speed back. If I don't have the altitude I can't get speed back without an engine.

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Went out today to do my 15 vs zero flaps takeoff climb challenge. :)  Walked into the hangar to a flat front tire. :bad_day-3329: So after installing a new tube off I went. :)

 

My field is 2420' elev. I set my altimeter to an even 2400'. The OAT was 92F and DA at 4950". Take off weight 1250 lbs. take off rpm is 4975 and runway length is 5500'.  Winds 300 @ 8 on runway 6. Both takeoffs from dead stops at exactly the same place. Rotated as soon as possible in both settings and 15 leaves the runway much sooner and at a slower speed. Climbed at 60 knots in 15 and 75 knots  in zero. Never saw oil temps over 204F :clap-3332: , but I only climbed maybe a total of 600'  each time before reducing throttle to come back to land.

 

First was 15 flaps and at the end of the runway I was 500'. :clap-3332:    ​If it had been colder outside like the winter that altitude would increase and so would your safety margin.

Then I did zero flaps and at the end of the runway I was 400' which is 100' lower than the 15 flaps. :o

It has always been this way since I bought my 2006 CTSW. At 500' at the end of the runway I can make a 180 degree turn back any day of the week :) and I have practiced so it's very doable. At 400' in zero may be iffy :fainting-1344:  if you delayed even for a split second. I'm pretty sure I can make it, but would prefer that extra 100 ft. in altitude.

 

These results were repeatable a second time. 

 

So 15 flaps gets you higher by the end of the runway versus zero flaps, still. ;)

Which in  my mind is safer with the extra altitude which also gave me more altitude during the entire climb over the runway in a landing configuration in case the engine quit. Lower the nose and land. Nothing more to do.  ;)

 

p.s.

I'll give you that zero flaps in a race would get to the end of the runway faster, but the turtle won that race, too. :giggle-3307:

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I flew a route that I normally fly at 12,500 today with a passenger and I ended up flying a bit lower so I could keep my speed up.

 

I needed to go from the -6 setting to the zero setting a number of times in order to clear terrain.  We were operating even in box canyon's with minimal room to turn around and no way out but the way in.

 

So now that I know clean climbs best, why use more flaps?  With the reflex setting I was indicating 80-90kts and climb was intermittently available.  When I used the zero setting to clear the terrain I would suddenly have 500-1000fpm climb and obviously be in a very good energy state but my IAS goes into the 70-80kt range.  Bottom line is when at high altitude and maximum performance the 0* option results in instant steep climb.  

 

In a CTSW more flaps to get you over terrain works really well but only at 2 settings.  -6 to 0, in most cases.  0 to 15, for last chance cases.

 

It might not be 'by the book' but in the High Sierra where the air is in motion its a common and useful tool.  If like most people you cross with thousands of feet of extra altitude there is little need to ever add flaps.  Perhaps big sink that your cruise setting is too fast for and you want to have a more positve energy state and a steeper angle.

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Roger, I don't doubt your numbers one bit. The question is did you time how long it took to get to 500 feet? Could you make the 180 to the runway from 500 feet with 0° flaps, even thought you are just beyond the end? Likely by only about 2500 feet. Even with our short 3,600 foot runway I think I could have made the turn back, and even had time to switch to 15° flaps for landing. My test showed from a standing stop that both 15° and 0° got to 500 feet in the same amount of time, and from lift off 0° got there quicker. What you are getting with 0° flaps is best rate of climb, and it will always get you altitude quicker. With 15° you get best angle. You won't get to altitude as quick, but the ratio of climb to distance traveled allows you to be higher in a shorter distance.

You still haven't provided any numbers backing your claim that the CT will climb faster with 15° flaps. If you do I will have a hard time believing those numbers.

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Hi Tom,

 

"Roger, I don't doubt your numbers one bit. The question is did you time how long it took to get to 500 feet?"

 

 

We're saying the same thing. Read your second to last sentence.

 

This is what I have been saying all along. It isn't a race or about speed for me. It's altitude in the shortest distance over the runway and at the end where I would still have a very good chance to save myself if things go south when I make flap and throttle changes. Zero isn't bad except I'm out past the runway and it could be the difference between an easy 180 and safe landing or not. If I had to clear trees at the end and then had an issue with zero flaps I'd be farther out from the runway and probably couldn't clear the trees on the 180.

I only care about my altitude at the end of the runway. Zero gets me to the end of the runway a tad faster, but I have to go out farther off the end of the runway to get to 500'.

I have more altitude over the runway while climbing than zero does. For me it isn't a race it's all about the shortest distance and proximity to the runway.

 

I think Newton was helping today. :eyebrow-1057:

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Roger, I'm not dogging how you make your take offs, in fact I do them the same way. The problem is what you do and what you are saying are 2 different things. Here is a quote from you earlier in this thread. "What I want is faster climb to have the most altitude by the time I reach the end of the runway." The whole point is a faster climb doesn't give you more altitude at the end of the runway, because of the longer ground roll and additional acceleration. What is giving you more altitude at the end of the runway is a slower climb at a steeper angle, with the added benefit of getting off the ground quicker so you have more time to climb. So yes, you do have more altitude over the runway than with 0° flaps, but you are not climbing faster.

 

For me it is a race. Not to the end of the runway, but rather to a safe altitude in the shortest period of time. Based on the testing I think it is a wash from a standing stop to 500 feet. Anything beyond 500 feet and 0° flaps will get you more altitude in a shorter period of time. BTW we have shorter runways around here, so I am beyond the end of the runway when I reach 500 feet regardless of which method I use.

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