I've been trying to nail the new Iceland landing challenge in the C152 and I'm really struggling with vertical speed at touchdown. I can place the aeroplane within 5 feet of the landing spot if I ignore the force of the touchdown but no matter how I try to flare, it seems like coming in at the usual 60kts over the threshold means I'm carrying too much speed to bleed off quickly.

By 500ft on finals I'm aiming to be trimmed for 60kts with 20 degrees of flap. Engine's somewhere between 1200-1400rpm depending on the approach profile - I have no fixed setting because power = rate of descent. My flare usually leaves me floating at 2-3ft for about 6-8 seconds while I steadily increase the yoke backpressure to keep the nosewheel high so my touchdown is mains first. Either that or I slam it on like a ton of bricks falling off a skyscraper.

What am I doing wrong here? I'm using the JPLogistics C152 mod.

Latest version?  V0.99?  It can float a bit, but no worse than the default C172 for me.

Maybe trying too hard Ian. 

Why not use 30 degrees of flaps that will shorten your float time. 

Well 60 kts is the best glide speed for the 152 so optimum for floating 😄

The book approach speeds for the 152 seem to assume a student pilot and are quite high, presumably to make allowances for inexperienced pilots and errors.  Basically they seem to assume the 152 pilot is a student on first solo and give them a bit of leeway for possible errors and missed approaches.

Using the "rule of thumb" of 1.3 times stall speed you will find 60 kts is about the correct speed for a flapless landing.  With 30 degree flaps out your stall speed is actually down around 35 to 40  knots (depending on airframe) giving an approach speed down around 50 knots rather than the 60 kts book speed. ( It is worth noting that the old 40 degree flap 152's did not actually acquire a noticeably lower stall speed with 40 degree flaps out, 40 degrees of flaps acted more like air brakes allowing a crazy steep descent.)

Even an approach speed of 55 kts will make a big difference. 

Approach speed in the sheet below is 55 to 65 kts:

https://www.purdueaviationllc.com/storage/app/media/Data Sheets/C152 Data Sheet.pdf

Here is an example where the recommended approach speed is listed as "55 to 65"  knots and  the recommended c152 short field approach is 55 kts:

http://www.bemoair.com/oldpages/postupy/checklist-c152t.pdf

TLDR - an experienced pilot familiar with the aircraft (in other words has tested the actual landing configuration stall speed at a safe altitude) doing a short field landing with no crosswind should be fine crossing the threshold at 50 to 55 knots (55 is definitely safe) - though do not try that as a student with your instructor sitting next to you, you will give them a heart attack.

Edited June 28, 20214 yr by Glenn Fitzpatrick

Thanks for the advice, Glenn. 55kts on final does help quite a bit. Now my flare only lasts for 2-3 seconds before I plonk it on like a sack of spuds!

Gees gives me an average of -83fps at touchdown with G forces averaging around 1.3G. I feel like that's excessive and I should be around 1.1-1.2G from a properly judged flare. So far I've only smashed it in once (2G!) from flaring too low. Work still to be done.

I wonder if I might need to extend my downwind leg a bit so the descent on final isn't quite as steep?

Yes, v0.99 of the JPLogistics mod

Edited June 28, 20214 yr by lambourne
mod version

If your approach is steep the traditional Cessna "lazy" landing method of cut the throttle and gradually pull the yoke all the way back as she slows will work, but may not give the most elegant landing.

It is possible with the lower approach speed and a steep descent you may need to apply a tiny touch of power (1200 to 1500) in early flare to arrest the descent. Just experiment and see what works.

As a student pilot, we were taught 60 kts for full flaps,  65 kts for 2 notches if flap and 70 kts for a nil flap landing in the 152 and I believe the 172 was about 5kts faster (didn't fly the 172 very often).

That certainly includes a pretty good margin for safety and error, but when learning to glide many years before, if I recall correctly, we were taught to use a given approach speed plus half the wind speed which makes sense for any low speed flying in my experience.

I have to say that I would always add a little extra speed in the C152 when the wind was a bit strong or gusty, but of course that will mean a slightly longer flare which is fine normally, but not for a short field landing (I would use 55 kts for those).

 

I tweaked my technique a bit to drop straight to flaps 20 after passing the downwind threshold. Previously I was dropping flaps 10 there and selecting 20 straight after rolling out on final. What a difference! Combining that with the 55kt approach was almost like flying a different aeroplane. Having less energy put me much lower on base and final than before.

The touchdowns are much easier to control as a result. All 1.0G - 1.1G with one very late flare slamming it in at 1.87G. In terms of fps, -37 was the best and -72 the worst of five (not counting the -175fps for the bad landing!)

Next I'll try the 60kts approach with the straight-to-flaps-20 technique. I'm determined to master this!