Cruise Speed Vs. Climb Rate

easik

easik

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easik
I'm going to do a video piece on this soon. I like to get your take on it. Since I've been flying or talking about airplanes, cruise speed is generally what people prioritize when it comes to the aircraft's performance. Everyone wants to go fast, but you have to get to your cruise altitude first right?
Anyway, the more I learn about different types of airplanes, the more this question comes to mind.

So which should you prioritize? better climb rate or better cruise speed?
Which is more important? and why?
Also what's been your personal experience?

Thank you.
 
Useful load and climb performance.
Where I fly, in the mountains, cruise speed won't get you out of trouble. Climb performance might.
 
Depends on the trip.

Recently went from central AL to the NC coast, 3 hours with a gentle tailwind. I spent about 10 minutes from crossing the Hold Short line to leveling off. Then 2:30+ in level cruise and just over 15 minutes descending power on.

Doubling the climb rate will save less than five minutes, while increasing cruise speed by 10 knots will save ten minutes; pop 25 knots on there and save more than 20 minutes.
 
Getting to altitude in shorter time is a good thing on a hot day. The cabin will cool. The engine will get more cool air. Typically less traffic to worry about.

That said, when climbing to, let's say, Eight Thousand Five Hundred you have to choose between Best Angle, Best Rate, Cruise Climb, or some combination of the above.

My opinion? Once I'm 1,000' above the highest obstacle I'm going with Vy or faster. I'd rather give up some vertical speed to get more air flowing over the engine.

Mind you, at gross weight I can see 1250ft/min so if I shallow that out to 750ft/min I'm adding, what, 2-3 minutes to the climb?

When I was flying the Cardinal I'd usually establish a cruise climb of about 500ft/min and take whatever speed I got. I'd have 3 or 4 up if I was flying that plane. So shallower climb made the passengers more comfortable. (And again, more air over the engine and we weren't in any hurry)

If the Cherokee Six could get more climb rate I'd have taken it in a heartbeat. [Kidding of course, but they don't exactly leap into the sky, even with 300HP]

So if nothing else... some thoughts... and my conclusion is "it depends."
 
Depends a lot on where you fly. DA doesn’t get over 3,000’ around here, so climb performance is pretty good all year. With that being said, climb performance is just as important as a fast cruise speed. I suppose you could double dip and get a turbo if you need both.
 
Ravioli said:
If the Cherokee Six could get more climb rate I'd have taken it in a heartbeat. [Kidding of course, but they don't exactly leap into the sky, even with 300HP]

So if nothing else... some thoughts... and my conclusion is "it depends."
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Uh yea.... I usually climb around 500 FPM at 110ish and still get hot in my T Lance. Step climbs are almost required in the summer.
 
I have both but the funny thing is I’m never in a hurry to get anywhere except to altitude in the summer months...:goofy:
 
I'll typically pitch for 1000 fpm at 100 knots...nice round numbers. It's enough forward speed to keep the cylinders cool, and an aggressive enough climb rate to get to that cooler air quicker.
 
How far are you going? It's all a trade off, but even at 500 fpm, getting to 8,000 feet will take only 16 minutes, which seems to be the sweet spot for the plane I fly, an SR 20, usually see 145 to 155 knots TAS there. I think I would opt for the faster cruise over faster climb.
 
Ryanb said:
Depends a lot on where you fly. DA doesn’t get over 3,000’ around here, so climb performance is pretty good all year. With that being said, climb performance is just as important as a fast cruise speed. I suppose you could double dip and get a turbo if you need both.
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This. Going from an NA SR22 to a Turbo SR22, I can cruise climb at 130 KIAS and 1000 fpm and when above 10,000 ft that translates to a similar true airspeed than I was when settled into cruise in my previous NA plane at 170 KTAS (LOP long range cruise). So I'm still climbing at 1000 fpm, heading towards my destination at the same speed as I would have been in cruise in the previous plane, and when I level off at 16,000-18,000 ft I get 200 KTAS instead of 170 KTAS. Longer climbs and not too crazy climb rate but it saves time overall.

At Vy and gross weight, I'd get about 1300-1600 fpm depending on temperature and altitude but I don't do that above 1500-2000 AGL lest the CHTs start getting hot.
 
Ryanb said:
Depends a lot on where you fly. DA doesn’t get over 3,000’ around here, so climb performance is pretty good all year. With that being said, climb performance is just as important as a fast cruise speed. I suppose you could double dip and get a turbo if you need both.
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That's crazy, just saw over 3000 this weekend in Indiana.
 
RudyP said:
This. Going from an NA SR22 to a Turbo SR22, I can cruise climb at 130 KIAS and 1000 fpm and when above 10,000 ft that translates to a similar true airspeed than I was when settled into cruise in my previous NA plane at 170 KTAS (LOP long range cruise). So I'm still climbing at 1000 fpm, heading towards my destination at the same speed as I would have been in cruise in the previous plane, and when I level off at 16,000-18,000 ft I get 200 KTAS instead of 170 KTAS. Longer climbs and not too crazy climb rate but it saves time overall.

At Vy and gross weight, I'd get about 1300-1600 fpm depending on temperature and altitude but I don't do that above 1500-2000 AGL lest the CHTs start getting hot.
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Rudy, what are you seeing for cruise speeds below 10,000 ?
 
@PaulS this is the G5 22T I did my transition course in. @RudyP plane is considerably faster. At 8K and about 3,500 lbs, maybe less, this is what we were showing, picture below, 154 IAS and 175 KTAS. The G3 is considerably faster.

upload_2018-8-27_12-39-13.png
 
Both are important. But if I didn’t have enough climb performance around the mountains here I would be circling to gain altitude before I can even cruise. That’s not good for saving time.
 
PaulS said:
Rudy, what are you seeing for cruise speeds below 10,000 ?
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LOP at 75-78% power I true at ~180 at 8000 or ~176 at 6000. I gain ~2 KTAS for every 1000 ft higher at the same power setting. So basically it’s 170 down low (<4k) all the way to 200 ktas at FL180. I get 219 KTAS at FL250 but I don’t go that high with very rare exceptions (no pressurization).

The sweet spot is the high teens.
 
Just thinking about it from an energy standpoint. Vy is about the most efficient (least drag speed). You will usually notice that the maximum range speed usually pretty close to Vy. So climbing at Vy you are losing the least amount of energy to drag and theoretically, should get you to your destination in the least amount of time using a Vy climb. I don't know if the actual numbers line up very well with the theory. But once you speed up to cruise speed you are now higher drag and trading efficiency for speed. The penalty for flying bit over Vy is probably pretty small so climbing a bit faster for cooling probably has minimal effect on the en route time. Your descent can also affect then enroute time, using a mild descent of about 250ft/min reduces the losses to parasitic drag over faster descents.

Brian
CFIIG/ASEL
 
I wish there was a quick sea level, flatland GA rule of thumb like: "For trips over XXXnm, cruise climb at V?, otherwise do..."

Then there's that darned headwind during the climb. Climbing near Vx or Vy almost feels like going backwards and takes forever in a respectable headwind.

And if you're doing a video maybe something about leaning during climb. A lot of fuel goes into that climb, unless you lean. But if lean aggressively during the climb your reducing cooling from the fuel. I've never been sure how aggressively to lean during climb.

A 500fpm cruise climb in the 182 makes for a nice deck angle for passengers and pretty decent ground speed. But the 182 can climb way better than that for the first 4000 or 5000ft.

In my rather limited experience, I generally prefer to climb around 100-110mph IAS. Still respectable climb rate and nice speed over the ground. But lower DA snd no obstacles to clear here so it can be done straight line enroute.
 
Not sure if it matters in some airplanes. Normal takeoff 70 to 80 knots, enroute climb is 75 to 85 knots. Just do 80 for both.
 
I like the ones with a positive climb rate with an engine inoperative. Usually solves the other two problems.
 
In the club 182 230hp I like ~100mph climb. Gives me good performance. She’ll climb the ladder fast until you hit about 5000-6000’ then you gotta just accept it’s going to be slower climb. Never took it above 10k. If I got stable air will make up the time on a nice power on decent.
 
easik said:
So which should you prioritize? better climb rate or better cruise speed?
Which is more important? and why?
Also what's been your personal experience?[/QUOTE

Prioritize: depends on mission. Are you a tail dragger trying to get out of a short unimproved strip or a 300hp 4 to 6 passenger plane on a long cross country.
Important: Get the tail wheel plane off the ground quick over the obstacles and out of harms way, 300hp 4 to 6 passenger plane leaving out of a field with a long runway take your time.
Personally: I have neither, my Sport is 150hp on a good day 750fpm @90mph, bad day 300fpm @ 90mp
Just saying...:)
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benyflyguy said:
In the club 182 230hp I like ~100mph climb. Gives me good performance. She’ll climb the ladder fast until you hit about 5000-6000’ then you gotta just accept it’s going to be slower climb. Never took it above 10k. If I got stable air will make up the time on a nice power on decent.
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I’ve not flown a 182 yet, but around here pattern altitudes are 5000+.

In a 172 I flew XC typically at 9500 or 10500 to stay out of the rocks.
 
woodchucker said:
Well, currently I’m flying a C150. Climbing at 60 kts gives maybe 150 fpm, cruise is maybe 80. Sometimes I think it would be faster if I got out and pushed.
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Gave me a good laugh :D
 
In the G5 I was flying it was right around 18. The TN will be lower. I did run the G5 down towards 16 a couple times to save fuel, but the engine didn't seem as happy
 
benyflyguy said:
In the club 182 230hp I like ~100mph climb. Gives me good performance. She’ll climb the ladder fast until you hit about 5000-6000’ then you gotta just accept it’s going to be slower climb. Never took it above 10k. If I got stable air will make up the time on a nice power on decent.
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I had mine to 13500 with 3 (larger) people on the way to Oshkosh. Probably had 45 gallons (half fuel) on board at that point....it would climb, but it definitely wasn't a brisk ordeal.
 
Depends on the airplane.

In the MU-2 I'm basically always doing best rate of climb up to altitude. That's the most efficient with the turbine since it burns so much fuel down low. Plus it's pressurized so the rate of climb/descent doesn't hurt anyone's ears. Max power (whatever the max power is that it can do at that altitude) the whole way up.

In the piston birds, I normally did a "cruise climb" to keep CHTs reasonable, especially in the 414. Sometimes I'd do a full power/max performance climb if there was a reason for it that benefitted me (such as "Are you above 1,000 FPM in the climb? If so I can get you up now").

There's no single answer. It depends on the plane and the pilot. Some people will just do max performance climb all the time period, some will do cruise climb all the time period. Usually it depends on what you're doing that day.
 
Climb, cruise, or fuel economy. Pick any two...

Airplanes are full of compromises, and what the most important priorities are depend on location and mission. Fortunately, there are many choices!
 
I don't see the problem. We just slow climb at 250 because of the speed limit. At 10K transition to .75M
 
chemgeek said:
Climb, cruise, or fuel economy. Pick any two...

Airplanes are full of compromises, and what the most important priorities are depend on location and mission. Fortunately, there are many choices!
Click to expand...

I can climb 2500+ fpm all day long, cruise 250kts, or do 170 knots on 8.5 gph. I chose all 3 ;)
 
Takeoff distance. Landing distance. To make those shorter makes the trip in between slower.
 
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