Climb Performance- POH Also Optimistic?

[Ragsf15e]

3 minutes ago, 802flyer said:

Ok so I may have been seeing some overly gloomy data based on factors that a number of you have pointed out, for which I'm super grateful. I went out flying after work today, right around sunset. OAT was 73F on the ground, winds calm with smooth air, density altitude 2400 when I started flying and 1900 when I put it in the hanger. Weight right around 2300lbs.

First takeoff I got the gear up, climb at 95 with flaps 15deg all the way to pattern altitude, climbing at 95mph and seeing between 1000-1200fpm with WOT and RPM around 2680-2700.

Second takeoff was same power settings and gear retract point, however I retracted flaps pretty much as soon as I cleared the trees and then pitched for 110mph (pretty close approximation of Vy at my DA tonight). Definitely sat in the 500-600fpm zone for maybe 10-15seconds while accelerating to Vy as the flaps came up, and eventually crept back up to back over 1000fpm. This is pretty much the workflow I've been using lately.

My home airport sits in a bowl between two lines of mountains (or "mountains" for those of you out west... my peaks are around 4-5k above runway elevation). In scenario #2, I definitely notice that period of time during climbout where flaps have just come up and I'm wallowing at only 500fpm for what feels like quite a while as I look at the hills. This is probably where I had spent most of my recent time glancing at the VSI and wondering if my performance was up to spec.

I had also tried looking at my track log data recently to extrapolate some average FPM numbers for my recent cruise climbs. It seemed like those were also showing around the 650fpm I had quoted previously. That said, my Savvy data shows that those days were definitely warmer/bumpier which would hurt performance a bit, especially if I lower the nose to 120mph for cooling/cruise climb. And things will fall off as I get up above 5k, bringing the overall average lower.

This evening I made a climb up to 6500 feet while holding 110-105mph, and was seeing around 1000fpm for the first half and not less than 750 for the rest. Turning power boost on at 5000ft brought me right back up near 1000fpm. Again, cooler and smoother air probably helped as well.

So in summary, things seem better than I had thought and much closer to book values. Everyone's input was super valuable in coming up with some real-world expectations and then getting out and testing. I think a huge contributing factor was the perceived/real loss of climb performance at relatively low altitude as I retract flaps. For my home airport and those with surrounding hills, I'm going to keep flaps in longer for a better angle-of-climb until I'm in downwind pointed down the valley. Seems I still get a reasonable rate-of-climb in that configuration to make it worthwhile....At least as a preliminary plan; I'll probably do some more testing with flap settings a few degrees more/less than 15deg to see if I can optimize a bit. And repeat testing with more loading and weather variation. Plenty of reasons to go flying, it seems.

Was feeling a bit despondent about potentially being limited to the Yankee versions of the approaches due to inadequate ft/nm performance on the missed, but seems there's hope for the Zulu minimums at this point (pending testing in hotter weather, of course).

Again, big thanks to everyone that chimed in with their own observations, as well as those that pushed me to be a bit more deliberate about assessing my performance data.

 

Full rich and 2700rpm you can likely climb a few thousand feet at Vx or Vy, but watch the CHTs.  Do you have an engine monitor with 4xegt and 4xcht?  At Vx and Vy on warm days cooling becomes a problem.  120mph works better but obviously avoiding your “mountains” is your priority.  Best angle is at Vx with flaps and gear up.  Lots of folks do not use flaps on takeoff, so that’s worth trying too.

[Marauder]

Mine has modded gaps, windshield, and cowl as well. With a density altitude in the 3000ft range, do you have a guess as to what you expect to see for the first few thousand AGL? I'll certainly do more testing of my own plane since they're all going to be a bit different after 50+ years of varying upgrades/upkeep, but I'm just trying to understand if I'm near par or not.

Density altitude was around 5400’ on this part of the climb today. Down lower I was seeing mid 700s.




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[802flyer]

8 minutes ago, Ragsf15e said:

Full rich and 2700rpm you can likely climb a few thousand feet at Vx or Vy, but watch the CHTs.  Do you have an engine monitor with 4xegt and 4xcht?  At Vx and Vy on warm days cooling becomes a problem.  120mph works better but obviously avoiding your “mountains” is your priority.  Best angle is at Vx with flaps and gear up.  Lots of folks do not use flaps on takeoff, so that’s worth trying too.

Thankfully I do have a good engine monitor with full instrumentation, so will be watching this closely. I'll definitely try a few variations. The local ODPs require a decent climb (430-470 ft/nm) to 3000-3300ft from an airport elevation around 800ft, so thankfully I should be able to transition to cruise climb after just a couple minutes.

Edited August 4, 2022 by 802flyer

[802flyer]

2 minutes ago, Marauder said:

Density altitude was around 5400’ on this part of the climb today. Down lower I was seeing mid 700s.




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Awesome pirep, (and panel)!

[Ragsf15e]

18 minutes ago, Marauder said:

Density altitude was around 5400’ on this part of the climb today. Down lower I was seeing mid 700s.




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Did you have any “special friends” on board?  Weight is a big factor, but middle weight, mine would be about the same.

[Ragsf15e]

21 minutes ago, 802flyer said:

Thankfully I do have a good engine monitor with full instrumentation, so will be watching this closely. I'll definitely try a few variations. The local ODPs require a decent climb (430-470 ft/nm) to 3000-3300ft from an airport elevation around 800ft, so thankfully I should be able to transition to cruise climb after just a couple minutes.

Yeah that could be close on a warm day with a heavy airplane, but doable light and cool.  If you are having to use Vx climb for ~2000’ ifr though, that brings up some additional thoughts…

[802flyer]

Yeah that could be close on a warm day with a heavy airplane, but doable light and cool.  If you are having to use Vx climb for ~2000’ ifr though, that brings up some additional thoughts…

Haha, yes very good point. My thought process here is wanting the performance to be able to confidently fly the ODP as-published. However I probably would not choose to launch into LIFR in a hot, heavy, Vx climb for the reasons you alluded to. Just want to make sure the limitation comes from my personal minimums rather than the plane’s performance.


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[Marauder]

Did you have any “special friends” on board?  Weight is a big factor, but middle weight, mine would be about the same.

No fatties sans one on this flight.


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