Another useful idea from Bob Kromer at Summit

[Bob_Belville]

Using V speeds for take off and climb:

Vx, best angle of climb, initial climb, gear up

Vy, best rate of climb, accelerate to Vy and raise TO flaps

Vcc, cruise climb, not in POH but use difference between Vx and Vy.

E.g., my E has Vx (clean) is 82 kias, Vy (clean) is 91 kias, so Vcc is 100 kias. You might have to use a higher Vcc for a long climb on a hot day but Bob suggests his rule of thumb is most efficient. 

[MIm20c]

I came away with him saying it was most efficient to retract flaps at Vy and safest to put some extra distance from the ground as quickly as possible. However, I didn’t get the feeling he wanted everyone to use Vy all the way up. 

[Hank]

Personally, I've almost always used Vx until clear of obstacles, then Vy to altitude. When I'm heavy, the runway is short and / or the obstacles high, I use Takeoff Flaps, and retract them when I'm looking down at the obstacles. Gear goes up once I'm in the air and in good control (per the Owners Manual).  

Works well for my C . . . .

[201er]

47 minutes ago, Bob_Belville said:

E.g., my E has Vx (clean) is 82 kias, Vy (clean) is 91 kias, so Vcc is 100 kias. You might have to use a higher Vcc for a long climb on a hot day but Bob suggests his rule of thumb is most efficient. 

That Vx number sounds a bit off, you sure about that?

[Hank]

3 minutes ago, 201er said:

That Vx number sounds a bit off, you sure about that?

Bob's numbers for the E are significantly higher than for my C below:

     Vx = 80 mph = 70 KIAS

     Vy = 100 mph - Altitude in thousands = 87 KIAS - Altitude 

     Cruise Climb is to 115--120 mph = 100--104 KIAS.

But his E is heavier and has a little more power, about 10% or so.

[orionflt]

VX in the E is 80 MPH/70 KIAS  VY=105 MPH/91 KIAS

 

[skydvrboy]

I know each model is different, but for my F, Vx is 94 mph (82 kts) and Vy is 113 mph (98 kts) at sea level decreasing to 102 mph (89 kts).  So that would make my initial cruise climb be 132.  Seems a bit fast, so climb would be slow, but you'd cover a lot of ground getting there.

 

[tigers2007]

How do you guys account for airspeed indicator error while trying to maintain Vcc while climbing to high altitudes?


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[skydvrboy]

6 minutes ago, tigers2007 said:

How do you guys account for airspeed indicator error while trying to maintain Vcc while climbing to high altitudes?

I don't.  I use IAS and if I don't like the climb rate, CHT's, or Oil temps, I adjust accordingly.

[Bob_Belville]

Very few of these V speeds are shown in the 1966 Owners Manual. And I won't swear they are all correct:

Other, unmarked Airspeeds:	mph		kts
Vlg	120		104
Va mgw	132		115
Va 2200#	122		106
Vx (to flaps)	80		70
Vy (to flaps)	95		83
Vx clean	94		82
Vy clean	105		91
Vg mgw	105		91
Vg 2200#	97		84
V window	150		130
V autopilot	170		148
V spdbrk
1.3Vso	75		65
1.3Vs	87		76

[Bob_Belville]

22 minutes ago, bluehighwayflyer said:

So 92.5 MPH?  Sorry, but that is too slow for cruise climb. Not even close.  I used to use 120 MPH in the J.  With the C I’ll start out with 110 MPH and see how the temperatures behave.

Jim

Jim, 100 kias is 115 mias. That's pretty close to your 120 mias.

[Bob_Belville]

37 minutes ago, orionflt said:

VX in the E is 80 MPH/70 KIAS  VY=105 MPH/91 KIAS

 

Are you comparing TO flaps to clean? I show 70 kias as Vx TO flaps. 91 kias is clean. 

[DualRatedFlyer]

3 hours ago, bluehighwayflyer said:

Hi, Bob. I was basing my comment on @orionflt‘s quoted M20E IASs of 80 MPH for Vx and 105 MPH for Vy. The average between them would be 92.5 MPH IAS which is just too slow of a cruise climb speed in any four cylinder Lycoming powered Mooney for good cooling, and especially so for the older models with less efficient cowlings. Or perhaps I misunderstood either his or your posts?

EDIT. Yes, your 115 MIAS would be about right. 

Jim

You take the difference between the two, then add that number to Vy to get Vcc.  

According to Orionflt's numbers Vy 105 - Vx 80 = 25.  Take Vy and add 25 to it and you get a Vcc of 130mph

https://www.flyingmag.com/technique/tip-week/calculating-cruise-climb-speed

[bradp]

Seems like Vcc is close to Vz.  

[Danb]

105-85=20+105=125 therefore Vcc is 125. I’ve generally climbed at 120 depending on temps. Many times my cruise climb approximates 130 which is a nice tradeoff. Again temps are supreme. Especially when at a safe altitude.

I was totally enveloped in Bob K’s talk, a world of knowledge provided to us within an hour, clearly one of the best INO of all the speakers, although Dan’s recap of his venture with co2 was riveting I could listen to both of them all day.

[jetdriven]

3 hours ago, bradp said:

Seems like Vcc is close to Vz.  

@testwest wrote a whole Thesis paper about Vz climb.  That’s the speed to use. 

[mike_elliott]

Bob Kromer and I have talked a number of times about the best[1] way to climb in a Mooney. As others have said so eloquently, Temps are a limiting, but not necessarily THE governing factor. Obstacles are primary with Temps secondary. Get out of the kill zone quickly (below 800'), then set up for cruise climb. 160 of you saw this slide last Saturday.

[1] Everyone has their idea of best way, this is the way I subscribe as does a number of Mooney CFI's and engineering test pilots. The POH should govern the operation of your aircraft.

[L. Trotter]

I would really like to have Bob Kromer back next year to provide further enlightenment.

[orionflt]

10 hours ago, Bob_Belville said:

Are you comparing TO flaps to clean? I show 70 kias as Vx TO flaps. 91 kias is clean. 

I just pulled the numbers out of the "66 E poh, the info was limited but the Vx number is TO flaps because if you are doing a Vx climb over an obstacle you would not retract your flap and would not use a clean configuration for take off.

Brian

[jlunseth]

I do my climb out the same way, but came at it through different calculations.  Vx is 71 kts, and Vy is 96, so my theoretical “Vz” is 83.5.  That’s approximately the number I use but my number is based on an article in AOPA magazine a few years ago.  The author actually ran a series of tests of what would happen in the event of engine loss on departure.  Vx was not best for two reasons.  First, they concluded that on average, a pilot does nothing for at least three seconds after engine failure, and in the attitude required to make Vx, the loss of airspeed is too high, the aircraft gets too close to Vs.  Vy was not best because it took too much time and distance to get to turn-back altitude.  You could make the necessary 270 turn without screwing it into the ground, but could not make the airport.  They found best glide was best.  So that is what I use, best glide.  

Best glide varies in my aircraft with gross weight from 81 to 85, I just use 85.  The plane accelerates to best glide pretty quickly once I get the gear and flaps up, I don’t wait with that any longer than necessary to get a positive climb rate.  

Turns out best glide is useful for all kinds of things.  It provides a good deal of margin from stall, so during takeoff and climb out, in the event of some kind of weather anamoly that causes airspeed to instantaneously drop, I am still a good 10 kts. above stall.  Base, and base to final, it gives me a buffer from a steep bank stall in the event of a too tight turn.  I would stall at 60 degrees, but not at anything reasonable.

So far, it has worked good.

[Bob_Belville]

1 minute ago, orionflt said:

I just pulled the numbers out of the "66 E poh, the info was limited but the Vx number is TO flaps because if you are doing a Vx climb over an obstacle you would not retract your flap and would not use a clean configuration for take off.

Brian

Brian, I agree with that operating procedure. But I suppose when we're looking for a delta airspeed between Vx and Vy to calculate Vcc we need to compare clean to clean which is 9 kts instead of 21 kts. So... Vcc is 100 kts instead of 113 kts. 

Actually, I usually climb at 115 to 120 kts but that results in 400 +/- ft/min climb. I'm going to try the 100 kts for a better climb rate and see if I can live with the temps.  

Of course Kromer is suggesting this as a rule of thumb to be rounded off and tweaked based on experimentation.

[orionflt]

1 minute ago, Bob_Belville said:

Brian, I agree with that operating procedure. But I suppose when we're looking for a delta airspeed between Vx and Vy to calculate Vcc we need to compare clean to clean which is 9 kts instead of 21 kts. So... Vcc is 100 kts instead of 113 kts. 

Actually, I usually climb at 115 to 120 kts but that results in 400 +/- ft/min climb. I'm going to try the 100 kts for a better climb rate and see if I can live with the temps.  

Of course Kromer is suggesting this as a rule of thumb to be rounded off and tweaked based on experimentation.

I am flying a '61 C and my numbers are similar to your E but my flight manual has a lot less information on  airspeed and performance, the one thing mine does state is to use 95 MPH on climb out. that actually works well for me and is what I use initially before transitioning to 120 MPH after i'm around 1000ft AGL. I also know the Early E's were using the same numbers but if memory serves me correctly, later models were using 105 MPH (also best glide speed) as the target number. 

[mike_elliott]

Bob is a board member of the Mooney Summit, Inc. and work permitting, will be in attendance. Bob's passion is Mooney. We are so fortunate to have him, Ken Yale, Ron Dubin, Seth Meyers and Lee Drumheller as board members. I am honored to have these fine gents as colleagues to help better the breed. Of all the board of directors I have served on over the years, this is without a doubt, the finest.

[Bob_Belville]

6 minutes ago, jlunseth said:

I do my climb out the same way, but came at it through different calculations.  Vx is 71 kts, and Vy is 96, so my theoretical “Vz” is 83.5.  That’s approximately the number I use but my number is based on an article in AOPA magazine a few years ago.  The author actually ran a series of tests of what would happen in the event of engine loss on departure.  Vx was not best for two reasons.  First, they concluded that on average, a pilot does nothing for at least three seconds after engine failure, and in the attitude required to make Vx, the loss of airspeed is too high, the aircraft gets too close to Vs.  Vy was not best because it took too much time and distance to get to turn-back altitude.  You could make the necessary 270 turn without screwing it into the ground, but could not make the airport.  They found best glide was best.  So that is what I use, best glide.  

Best glide varies in my aircraft with gross weight from 81 to 85, I just use 85.  The plane accelerates to best glide pretty quickly once I get the gear and flaps up, I don’t wait with that any longer than necessary to get a positive climb rate.  

Turns out best glide is useful for all kinds of things.  It provides a good deal of margin from stall, so during takeoff and climb out, in the event of some kind of weather anamoly that causes airspeed to instantaneously drop, I am still a good 10 kts. above stall.  Base, and base to final, it gives me a buffer from a steep bank stall in the event of a too tight turn.  I would stall at 60 degrees, but not at anything reasonable.

So far, it has worked good.

For my E, Vy and Vg (at gross) are both 91 kts.  I round to 90 kts as my best climb or descent ias. (If i'm alone Vg is closer to 85.)  

[jlunseth]

Amazing.  Mass agreement in the forum. 

Now, are you climbing leaned out or full rich.....