2-33 landing speed

General Club Information in the last 180 days - Posts open to Club members only
Kenneth Voort
Posts: 29
Joined: Mon May 24, 2021 8:15 am

2-33 landing speed

Post by Kenneth Voort »

As you may know, I've recently re-soloed in the 2-33, after a good long pause of 25 years or so.

From my retraining, assuming I recall correctly, I was taught to flare at 55mph. Now, while 55 seems like a fine speed to fly an approach, it hasn't seemed to me to be a fine speed to land at. On my recent flights, I felt like I was screaming to touchdown at 55. I feel like there's too much energy at that speed; I can best compare it to flaring at 80kts instead of 70 in the Grob I'm doing my power training in - it just feels too fast. I can't back that up with much experience, but it just feels too fast to me. Is it possible I misunderstood, and that while a circuit should be flown at 55, a landing should be executed slower?

Here's the pertinent section from the 2-33 PoH:
Touch down:

Can be done with dive brakes open or closed, although it is preferable to land with them open. With dive brakes open, the glide path is quite steep, therefore, a flare-out must be executed at 43-46 mph.
Emphasis mine.

So have I missed or misunderstood something? I thought the idea was to approach and flare at 55mph - but dagnabit that feels too fast to me, and the PoH seems to agree...
With grace and beauty, Strength and cunning She’ll stay aloft — until; Inevitably — she loses. And must glide earthward. And lie there helpless, Lovesick for the sky.
Eitan Rotbart
Posts: 6
Joined: Tue Apr 27, 2021 11:14 am

Re: 2-33 landing speed

Post by Eitan Rotbart »

Wayne tought me that the landing is speed is ~1.5 * Vstall + 1/3*wind speed (Vstall for the the 2-33 is 35 mph, so your minimum approach speed should be 51 mph if there's no wind), meaning that in most cases it will around 55-60 mph.
The I understand it from my point of view (as an aerospace engineer [kind of]) - If you come to slow, your sink rate will be higher and therefor you will land harder, so if you come faster you can land smoother but your landing will be longer until full stop, furthermore, if you come in faster you have more air flow on the control surfaces and hence will allow you to clear the runway using the rudder (meaning, you can use your rudder more effectively to turn away from the runway)

EItan
Doug Carman
Posts: 15
Joined: Wed Jul 01, 2020 12:10 pm

Re: 2-33 landing speed

Post by Doug Carman »

The approach speed should be stall plus a half, plus 1/3 of the wind. So 51 no wind, 55 at 12 mph, 60 at 27 mph and so on. Do the calculation on the ground before you launch, so if you run out of time on downwind to calculate, you have the speed ready. Our approach speed is designed for safety, control, and also gives us maximum penetration into a headwind. You can use the same speed for flying upwind, keeping in mind that the upper winds are higher than on the ground.

The last landing you made, Ken was with NO headwind, so your ground speed was higher. If you flare with about 1/3 - 1/2 spoilers and get the nose up during the actual landing, your airspeed and ground speed will be less than approach speed, quite close to what the book says. But be sure to keep the approach speed until the flare.
Kenneth Voort
Posts: 29
Joined: Mon May 24, 2021 8:15 am

Re: 2-33 landing speed

Post by Kenneth Voort »

Upon further reading, the feedback I'm getting is mostly correct - the manual does say to add the wind speed to your landing speed in "strong winds", although it doesn't define "strong winds". Interestingly, though, it recommends calculating a landing speed based on best lift/drag ratio, not stall speed - that's something I've never encountered before.

Best L/D is about 52mph dual, and 46mph solo, if I'm reading the performance curves right. That's enough to make a bit of a difference, whereas the stall speed only differs by about 2mph dual vs. solo.
Eitan Rotbart wrote: Mon Jun 21, 2021 11:46 pm Vstall for the the 2-33 is 35 mph
The PoH tells me it's actually 31mph solo, or 33mph dual (which then will obviously depend on the exact weights of the occupants). 35 vs 33 wouldn't make much difference to me, but 35 vs 31 would. It would mean flaring at 50 instead of 55, if I base my touchdown speed on stall speed.
Doug Carman wrote: Tue Jun 22, 2021 8:01 am The approach speed should be stall plus a half, plus 1/3 of the wind. So 51 no wind, 55 at 12 mph, 60 at 27 mph and so on. Do the calculation on the ground before you launch, so if you run out of time on downwind to calculate, you have the speed ready. Our approach speed is designed for safety, control, and also gives us maximum penetration into a headwind. You can use the same speed for flying upwind, keeping in mind that the upper winds are higher than on the ground.

The last landing you made, Ken was with NO headwind, so your ground speed was higher. If you flare with about 1/3 - 1/2 spoilers and get the nose up during the actual landing, your airspeed and ground speed will be less than approach speed, quite close to what the book says. But be sure to keep the approach speed until the flare.
Sorry for repeating, but the PoH tells me to base my landing speed on best L/D, not on stall speed. That is contrary to every other plane I've ever flown, but hey - that's what the people who designed, built, and tested the airplane say... so who am I to argue with that?

If I land at best L/D solo, that's 45mph. If I assume a 10kt headwind, then, yes, it's 55 (ignoring the mph to kts conversion). If I do that dual, that's, let's say, 50mph dual with no wind, plus the wind factor. 55 makes sense in that case.

So yeah, I still think that 55 is a bit fast to land these boats solo, barring at least a 20km/h headwind.

It's entirely possible though that flaring at 55 with no wind, solo, is too fast, because it assumes a wind correction that I haven't needed to apply on my more recent landings. But it's not just my groundspeed that feels too fast at 55 - my airspeed feels a bit too fast, the controls feel a little tight to be landing with, etcetera... sorry, it's hard to communicate this effectively.
With grace and beauty, Strength and cunning She’ll stay aloft — until; Inevitably — she loses. And must glide earthward. And lie there helpless, Lovesick for the sky.
User avatar
Jock Proudfoot
Posts: 13
Joined: Sun Jul 05, 2020 11:21 am

Re: 2-33 landing speed

Post by Jock Proudfoot »

.
FAA Glider Handbook, Chapter 7
The FAA wrote:The approach should be made using spoilers/dive brakes as necessary to dissipate excess altitude. Use the elevator to
maintain the recommended approach airspeed established by the manufacturer.
If no approach speed is recommended by the manufacturer, use 1.5 VSO
...Strong crosswinds, tailwinds, or high sink rates that are encountered in the traffic pattern require the pilot to modify
the individual pattern leg (downwind, base, or final) and to adjust the approach speed as appropriate.
It is recommended that half of the gust factor be added to the normal approach speed to compensate for wind gusts and sink.
LINK - See page 7-23
.
Kenneth Voort
Posts: 29
Joined: Mon May 24, 2021 8:15 am

Re: 2-33 landing speed

Post by Kenneth Voort »

Well, it's not the approach speed I'm rattling my brain about, it's the touchdown speed. The manual actually doesn't recommend a specific approach speed, so I'll take that 1.5 Vso. It only recommends a flare speed.

But the link you provided recommends half the gust factor - which is what I've always done, before taking up soaring again. Sometimes a bit more, as I'm training out of YTZ, which is not friendly to crosswind landings and has three times the runway I need, so rounding out a bit hot is not too much of a concern. We're not doing that, though. We're recommending adding the entire wind speed, and I've seen no mention of the gust factor prior to yours.

So on one hand, I have the manual, that says to touch down at 45mph solo + all the wind, then I have the FAA glider handbook, which says to touch down at 1.5Vso + half the gust, then I have my power training that tells me 1.3Vso + half the gust, then I have my York Soaring training that tells me "flare at 55". Which one is correct? If I have to pick one based on feel, then I can't ignore my "this feels too fast" voice.

Wow. I didn't realize I'd be exploring the minutiae of this so much. But hey, I haven't crashed yet, so I must be doing something right.
With grace and beauty, Strength and cunning She’ll stay aloft — until; Inevitably — she loses. And must glide earthward. And lie there helpless, Lovesick for the sky.
Kenneth Voort
Posts: 29
Joined: Mon May 24, 2021 8:15 am

Re: 2-33 landing speed

Post by Kenneth Voort »

Then again, today was a high crosswind day, I'd estimate 12G20kt. On a solo flight, I flew my approach at 55 as recommended, on a right circuit for 32. Even that felt too slow on base. I cut my base short enough that I flew right over Tom's head and still felt like I needed more airspeed on final - it was a kickin' crosswind. It was very gusty, and even with that speed, I had a wing drop while turning downwind to base.

Tom rightfully chided me for overflying the flight line on final (I was wondering if anyone noticed it - but he doesn't miss much). It was a harrowing approach through what I felt was some pretty good wind shear and so was antsy about turning too tight to final, so a nice gentle turn to final seemed right, but that put me a bit too far right. Even considering that I was intending to start from the trailer side and land towards the field side, to take 20° or so out of my crosswind, it was a bit much. I was quite happy to fly that approach faster than I've previously been arguing, though.

The point being - I was wrong on this count. Had I been flying for a 45mph flare, I very likely would have spun.
With grace and beauty, Strength and cunning She’ll stay aloft — until; Inevitably — she loses. And must glide earthward. And lie there helpless, Lovesick for the sky.
Stan Martin
Posts: 18
Joined: Wed Jul 01, 2020 12:12 pm

Re: 2-33 landing speed

Post by Stan Martin »

Interesting discussion. Vso + .33 Vso = as close as does not mater, best L/D. That is on any aircraft I fly. I will leave it there.

The question that trips many pilots up is approach speed on down wind landings.

Another good question is, do you know the max cross wind component for your aircraft? That is good to know for many reasons.
Last edited by Stan Martin on Thu Jun 24, 2021 3:01 pm, edited 4 times in total.
Doug Carman
Posts: 15
Joined: Wed Jul 01, 2020 12:10 pm

Re: 2-33 landing speed

Post by Doug Carman »

Stall plus one third, as Stan points out is close to L/D for high performance gliders and power planes. However, with 2-33s, the performance is not as high, and often flown by low time pilots. Therefore the extra speed is good, in that a draggy aircraft can lose speed quite fast. Our procedure gets that speed set early in downwind and leaves it there, until you begin to level out over the runway, and flare into touchdown. Again, that speed in a 2-33 gives you the best ground speed into a headwind. Even in the towplanes, we are flying at least stall plus a half on short final.

As you know, Transport Canada suggests stall plus a third plus all of the wind. You need to know that for the exam, but in real life the York formula is more practical.
Stan Martin
Posts: 18
Joined: Wed Jul 01, 2020 12:12 pm

Re: 2-33 landing speed

Post by Stan Martin »

I would agree. A (little) extra speed in a 2-33 is not a problem on normal approaches because of the huge amount of drag. It looses speed quickly after the flair.

A held off landing is not a bad thing either, if you know how to handle the aircraft and unless you are not running out of runway. The concern is, do you know how to do a held off landings? It is easy to get into PIO's with too much speed. We see that often in new pilots. So high speed approaches need to be measured carefully. It is not a matter of a number that is pulled out of the air, so to speak. That is why we ask each time in training why the approach speed was chosen?
Post Reply