Slowin' Down

Guest Discussion
1

Interested to know how you early SR20 owners handle descents without shock-cooling the engine. Particularly if you have to lose altitude quickly.

I hold a SR22 position. My biggest concern — which makes me worry in the dark of night that I might be buying too much plane — is how you get from 180 ktas cruise to 120 pattern entry (or 110 or 100) without the use of landing gear brakes and with quite low flap extension speeds.

There is a growing body of experts who think shock-cooling is an overrated problem . . . an old wive’s tale. I hope they’re right. But assuming it is a real threat to engine integrity, how are y’all avoiding it during your descents?

Final thoughts: I hope Cirrus will work as hard to raise flap extension speeds as they are to raise useful loads. Mooney enjoys an active aftermarket in speed brakes . . . but STCs don’t happen overnight and installing them in composite wings may pose its own challenge.

2

Interested to know how you early SR20 owners handle descents without shock-cooling the engine. Particularly if you have to lose altitude quickly.

I’ve chosen not to believe in shock cooling, but even if you do I don’t think getting slowed down is much of an issue in the SR20, so long as you get an opportunity to level off for 20 seconds or so. If you want to pull the throttle back gradually, you’ll have to plan early, of course, but I don’t have any trouble slowing down even when careening down well into the yellow arc. I was doing almost 190 indicated into SJC last week (on a very calm evening) and didn’t start slowing down until I was at 1200 feet or so somewhere between the Pruneyards and the airport (less than five miles out.)

It doesn’t slow down so well when you’re descending, so you do want to get those flaps out before starting down the hill on an ILS, and watch your airspeed once you do.

3

180 knots to pattern speed ?.That is nuts. Not really a pilot with a high performance endorsement? I hope to god you get the proper training.If you are that behind maybe you need more flight instruction in a fast complex then asking for advice on the internet.Hands on bud.Don’t go and throw 300k on a bird and ram my butt with careless flight management.Please get proper training.

4

Interested to know how you early SR20 owners handle descents without shock-cooling the engine. Particularly if you have to lose altitude quickly.

…

Rich,

I don’t think you’ll have much of a problem. I made the transition to a similarly slippery and high performance single, a Bonanza, a little over a year ago w/ little problem. Here’s a relatively simple procedure: start pulling the power back about 1" every 30 seconds when you are way out. By the time you get to the pattern, if you’re being really conservative, you’re at 18". To drop speed to Vfe, if you’re not already there, pull up, level off, and you’ll soon be slow enough to add drag. As you get more comfortable, you can keep the power in longer. If you do find yourself too high and fast, something that often happens to Bonanza drivers (who often have more money to buy HP than time/energy to fly), ask ATC for a 360, they will usually accomodate you.

I also don’t know whether to buy the shock cooling argument, but to play it safe, I try to keep the cooling rate low. Also, when you plan ahead, your descents work out better. At this point, even if TCM and Lycoming said that shock cooling wasn’t a problem, I’d still pull power way out. Doing so makes it less likely that I’ll get behind the plane.

I think you’re question is a good one. I think the flame you got from someone calling themselves “757driver” was way out of line.

Robert Bedichek

PS. I’m sorry about the multiple posts that I made

a few days ago. It was some interaction between this site and my browser that I still don't understand. Hopefully, this post will only show up once!

PPS. An instructor of mine told me that he checked out cooling rates. He found that he could pull power in some A/C (sorry, I forgot which, but it was in the 300 HP range and was turbocharged). He found that he could keep the cooling rate well below the 60F/minute specified by the engine manufacturer and pull power at 1"per 20 seconds, which is a lot faster than the standard of 1" per minute. The unexpected (to him and me) thing that blew the cooling rate limit was when his copilot opened the cowl flaps before they had finished the landing roll. The sudden cooling from the additional air on roll-out was the worst thing he had done.

PPPS. I don’t claim to be an expert and welcome corrections.

5

I fly an A-36 now. Please help me understand something about shock cooling. Since the SR20 is water cooled and my Bonanza is air cooled, is the SR20 less prone to shock cooling?

Also, I have been using the gear extension as an air brake on approach in the A-36. Will have to learn a new protocol in the SR20 - and I can hardly wait!

6

Interested to know how you early SR20 owners handle descents without shock-cooling the engine. Particularly if you have to lose altitude quickly.

Firstly, remember that 180ktas is not 180 indicated, but the 120 flap speed limitation is an indicated speed limitation.

Having said that, the other comments about cruise descents are pretty much right - Kevin’s guess of 6 miles/1000 ft is right on the money. I use that and it works well. I don’t pull back the power for descent (seeing 180 knots on the GPS is fun) just bring the mixture up then ease the power back when levelling off or at some appropriate point in the descent. If you plan to level off about 5 miles from the circuit, then by the time you get to the circuit area you are rarely doing more than 140 indicated, and getting back to 120 from that is easy.

I would expect that with the SR22, much the same procedures would apply, except that you might want to reduce power earlier, and perhaps allow a little more distance for descent.

But really, now that the flap speed is 120, it’s not a big problem - just requires a little planning. I don’t see any need to have the flap speed increased further.

7

To post this kind of slam, anonymously, to someone (a) who is using his real name and (b) about whom you know nothing contradicts the professionalism you are claiming to represent. If this is the way “757 drivers” react, my respect for professional pilots goes down.

You could have started by asking Rich Karlgaard if he’s getting extensive flight training, which he definitely is. His question is a genuine question, not a shortcut for experience or proper training. J Fallows

8

Actually, I soloed in an A36.

Peace, brother.

180 knots to pattern speed ?.That is nuts. Not really a pilot with a high performance endorsement? I hope to god you get the proper training.If you are that behind maybe you need more flight instruction in a fast complex then asking for advice on the internet.Hands on bud.Don’t go and throw 300k on a bird and ram my butt with careless flight management.Please get proper training.

9

To post this kind of slam, anonymously, to someone (a) who is using his real name and (b) about whom you know nothing contradicts the professionalism you are claiming to represent. If this is the way “757 drivers” react, my respect for professional pilots goes down.

You could have started by asking Rich Karlgaard if he’s getting extensive flight training, which he definitely is. His question is a genuine question, not a shortcut for experience or proper training. J Fallows

Not enough guts to say how you are. Go ahead and hide behind 757driver.

I guess you were born driving a 757. Well most of us don’t. I remember when I first got my Mooney 231, it did take some time getting used to, it is not hard but we are not as lucky as this rude 757driver. These are the same people that makes tons of money, work very few days a month and yet make companies go broke because they are not willing to work an extra hour or their meals were not like a meal for a King. I am sorry but I just don’t have room for those guys. Get out of the seat and give room for someone that wants to work for a living…

Woor

10

I don’t think you’ll have much of a problem. I made the transition to a similarly slippery and high performance single, a Bonanza, a little over a year ago w/ little problem. Here’s a relatively simple procedure: start pulling the power back about 1" every 30 seconds when you are way out. By the time you get to the pattern, if you’re being really conservative, you’re at 18". To drop speed to Vfe, if you’re not already there, pull up, level off, and you’ll soon be slow enough to add drag. As you get more comfortable, you can keep the power in longer. If you do find yourself too high and fast, something that often happens to Bonanza drivers (who often have more money to buy HP than time/energy to fly), ask ATC for a 360, they will usually accomodate you.

Rich

Mr. Bedichek’s comments make good sense to me in light of my own experience. Whether it’s the 260se (quite a slippery plane compared to a stock 182), 182RG, or the SR20 on the Kansas trip, gradual power reduction while still some distance away works well, especially for IFR when you’re anticipating having to do an approach.

For VFR descents @500 fpm to a VFR landing in my 260se, I allow five miles for every 1000 feet of altitude to lose (in the SR20, more like 6 miles), then add 3-4 miles as a cushion. This allows some time in level flight approaching the pattern to slow down. So for example if I’m cruising at 6500 feet at 22" MP and pattern altitude is 2500 feet, I’ll start the descent (20 + 4) miles out by reducing power to 20" and trimming for 500 fpm down. I adjust power to maintain 18"-19" during the descent; at level-off, the plane slows readily to 120 KIAS where the first notch of flaps comes out, after which it’s a piece of cake.

As for 757 driver, “Illegitimi non-carborundum”

11

I fly an A-36 now. Please help me understand something about shock cooling. Since the SR20 is water cooled and my Bonanza is air cooled, is the SR20 less prone to shock cooling?

Also, I have been using the gear extension as an air brake on approach in the A-36. Will have to learn a new protocol in the SR20 - and I can hardly wait!

Mike, the SR20 (SR22, also) is an air cooled engine. That’s the whole reason for this discussion.

Pete

12

I fly an A-36 now. Please help me understand something about shock cooling. Since the SR20 is water cooled and my Bonanza is air cooled, is the SR20 less prone to shock cooling?

Also, I have been using the gear extension as an air brake on approach in the A-36. Will have to learn a new protocol in the SR20 - and I can hardly wait!

The SR20 is powered by an air cooled Continental IO-360-ES 6 cylinder engine. Nothing water cooled in either the SR20 or the SR22. The Cirrus product does not offer cowl flaps and so operator control of engine cooling is limited to airspeed and power setting. Apart from this, any shock-cooling concerns are wholly conventional.

George