Leadville (KLXV) in an NA Mooney?

[BlueSky247]

Heh. This topic just came up in my ground school review. “At higher DA, expect higher angle of attack and higher induced drag.” 

[Ryan ORL]

4 hours ago, 0TreeLemur said:

I'm pretty sure I screwed up.  When I retract the gear in my J she quickly accelerates.   By the time I got off and she started to settle, I there wasn't enough runway left to land on.

This is also my experience.  Granted, I only have made like 5 or 6 takeoffs above 7000ft DA, but my memory of them is that the rotation is slow, and the initial burst of acceleration you normally get just isn’t there.  It feels like it takes forever to even get to gear retraction speed (which should be set at 65 KIAS I believe but I normally won’t command it until 70+), let alone Vy, but once you get them up, and get the flaps up, it starts feeling a lot more normal.

I agree that I probably wouldn’t pull them up over the actual runway because settling does happen, but you also use up pavement pretty quickly at those True Airspeeds so I’ve always been more concerned about the terrain that’s right off the runway end, which unsurprisingly feels a bit more immediate at those speeds and shallow climb angles, even for minor little hills and bluffs that don’t even show up on your charts.

[midlifeflyer]

8 hours ago, Ryan ORL said:

This is also my experience.  Granted, I only have made like 5 or 6 takeoffs above 7000ft DA,

That’s was a pretty average day in Denver. 

[Pinecone]

20 hours ago, Shadrach said:

You know, I’m not so sure your choice wasn’t the best. Unstable air and high DA…gear probably did not make that much of a difference and if you’d settled back on it would have been ugly.  Flying off the cliff with gear down seems like a reasonable strategy.

My thoughts also.

[Pinecone]

19 hours ago, 0TreeLemur said:

I'm pretty sure I screwed up.  When I retract the gear in my J she quickly accelerates.   By the time I got off and she started to settle, I there wasn't enough runway left to land on.

Not talking about enough to land and stop on, but the consequences of settling back to the runway with the gear up.  ie Prop Strike.

[donkaye]

My experience with ALL students has been that, even though they may want to, they just won't stay in ground effect.  In ground effect induced drag is reduced by an amazing 48%.  Everyone thinks they are going to hit the ground.  Why?  The Mooney wing is a little over 36 feet in length.  Ground effect is 10% of the wing length or about 3 feet.  But the landing gear extends about 3 feet.  So just as the wheels leave the ground you need to level the plane a few inches off the ground.  People just won't do that.  However, if you do, the plane will accelerate much more quickly to Vx, where you can then start your climb.

[M20C]

I flew in/out of Telluride in June to my cousin's wedding.  I figured just over 4000' ground roll and If I was not airborne (or close to it) by 4500' I would stop; 3 people, bags, 1/2 tanks, 180 hp (non-turbo) M20C.  Airborne by 4500' and she flew just fine.

[Ragsf15e]

27 minutes ago, donkaye said:

My experience with ALL students has been that, even though they may want to, they just won't stay in ground effect.  In ground effect induced drag is reduced by an amazing 48%.  Everyone thinks they are going to hit the ground.  Why?  The Mooney wing is a little over 36 feet in length.  Ground effect is 10% of the wing length or about 3 feet.  But the landing gear extends about 3 feet.  So just as the wheels leave the ground you need to level the plane a few inches off the ground.  People just won't do that.  However, if you do, the plane will accelerate much more quickly to Vx, where you can then start your climb.

I (and the FAA) agree that the reduction at 10% of airfoil length is about 50%, but 3’ is pretty low, especially for an inexperienced pilot.  It’s important to remember that the effect still reduces drag up to 1 wingspan, so maybe leveling off around 10’ and accepting a 25% reduction will be more comfortable and executable.  Additionally, just leveling off somewhere will let the speed build to Vx or Vy faster than trying to accelerate while climbing.

Edited July 12 by Ragsf15e

[donkaye]

2 hours ago, Ragsf15e said:

I (and the FAA) agree that the reduction at 10% of airfoil length is about 50%, but 3’ is pretty low, especially for an inexperienced pilot.  It’s important to remember that the effect still reduces drag up to 1 wingspan, so maybe leveling off around 10’ and accepting a 25% reduction will be more comfortable and executable.  Additionally, just leveling off somewhere will let the speed build to Vx or Vy faster than trying to accelerate while climbing.

Using a musical instrument as an example.  You'll never get anywhere without a lot of practice.  The same goes for flying.  Even a low time pilot should be capable of flying down the runway at no more than 1 foot.  It just takes practice.  For high DA the proficient pilot should be able to use ground effect to its maximum effectiveness and 25% reduction just doesn't cut it with me when it could be 50%.

[Shadrach]

25 minutes ago, Ragsf15e said:

I (and the FAA) agree that the reduction at 10% of airfoil length is about 50%, but 3’ is pretty low, especially for an inexperienced pilot.  It’s important to remember that the effect still reduces drag up to 1 wingspan, so maybe leveling off around 10’ and accepting a 25% reduction will be more comfortable and executable.  Additionally, just leveling off somewhere will let the speed build to Vx or Vy faster than trying to accelerate while climbing.

51 minutes ago, donkaye said:

My experience with ALL students has been that, even though they may want to, they just won't stay in ground effect.  In ground effect induced drag is reduced by an amazing 48%.  Everyone thinks they are going to hit the ground.  Why?  The Mooney wing is a little over 36 feet in length.  Ground effect is 10% of the wing length or about 3 feet.  But the landing gear extends about 3 feet.  So just as the wheels leave the ground you need to level the plane a few inches off the ground.  People just won't do that.  However, if you do, the plane will accelerate much more quickly to Vx, where you can then start your climb.

Beat me to it. If 10% were needed, no Cessna high wing would ever experience gound effect.  

[donkaye]

2 hours ago, Shadrach said:

Beat me to it. If 10% were needed, no Cessna high wing would ever experience gound effect.  

All the more reason to stay close to the ground and be grateful to own a Mooney.

[Ragsf15e]

28 minutes ago, donkaye said:

Using a musical instrument as an example.  You'll never get anywhere without a lot of practice.  The same goes for flying.  Even a low time pilot should be capable of flying down the runway at no more than 1 foot.  It just takes practice.  For high DA the proficient pilot should be able to use ground effect to it maximum effectiveness and 25% reduction just doesn't cut it with me when it could be 50%.

Fair enough.  Im sure you’re right, but we might be able to get 75% at 1’, no?  I guess I’m just being snarky, but I personally don’t think the juice is worth the squeeze if you need to maintain exactly 3’ above a high DA runway with the gear up in order to do it right.

[MikeOH]

13 minutes ago, Ragsf15e said:

... might be able to get 75% at 1’, no?  I guess I’m just being snarky, but I personally don’t think the juice is worth the squeeze if you need to maintain exactly 3’ above a high DA runway with the gear up in order to do it right.

EXACTLY!

I guess I'm okay with knowing that I'm not good enough to fly three feet off the ground down the runway, because I have the judgement to know I should just relax in the lounge if I need that kind of performance to depart at that DA

[Shadrach]

4 hours ago, Ragsf15e said:

Fair enough.  Im sure you’re right, but we might be able to get 75% at 1’, no?  I guess I’m just being snarky, but I personally don’t think the juice is worth the squeeze if you need to maintain exactly 3’ above a high DA runway with the gear up in order to do it right.

In my 20s, I might have made a few  passes that were low enough to net a 50% reduction in induced drag.  Of course, I wasn’t doing it to build energy; I brought plenty of that to the party.  I don’t think any of my instructors would have complimented me on my ability hold it in ground effect. My 25 year old self now feels vindicated by this thread!

[donkaye]

1 hour ago, MikeOH said:

EXACTLY!

I guess I'm okay with knowing that I'm not good enough to fly three feet off the ground down the runway, because I have the judgement to know I should just relax in the lounge if I need that kind of performance to depart at that DA

Sorry, call me crazy for thinking we should aim for a higher level of proficiency.  Of course you should use your superior knowledge so you don' have to use your superior skill, but you should have the superior skill in reserve in my opinion.   The greater the margin of safety the better in high altitude operations.

[N201MKTurbo]

18 minutes ago, donkaye said:

Sorry, call me crazy for thinking we should aim for a higher level of proficiency.  Of course you should use your superior knowledge so you don' have to use your superior skill, but you should have the superior skill in reserve in my opinion.   The greater the margin of safety the better in high altitude operations.

The last time I did that was about a year ago. I was departing 57AZ and there was a T storm about a mile off the end of the runway. It was pretty gusty and I wanted to get as much airspeed as I could before dealing with that beast. I got it off the ground and retracted the wheels and flew down the runway till I got 100 KTS. My cohort who dropped me off took a pic at midfield. I was eye to eye with him. It was pretty sporty down the runway and for the first minute of flight. 

[MikeOH]

1 hour ago, donkaye said:

Sorry, call me crazy for thinking we should aim for a higher level of proficiency.

Certainly that's a pithy and trite aphorism with which I would not argue.

But, we're discussing a pretty specific circumstance: departing at a high DA under conditions that REQUIRE flying at 3 feet off deck to perform a take off with an adequate(???) margin of safety.  I.e., when staying within a wingspan of the ground would be insufficient.

Sorry, call me crazy for thinking that developing the ability to fly 3 feet off the deck is NOT a proficiency I feel the need to gather.  In my opinion take off from a high DA airport is optional; you can wait for more favorable conditions, and/or offload weight.  To put yourself in a situation that demands that level of performance requiring such proficiency would be a stupid way to 'need' superior skill.  IOW, it would be a classic demonstration of a LACK of superior knowledge and judgement.

[donkaye]

55 minutes ago, MikeOH said:

 

Sorry, call me crazy for thinking that developing the ability to fly 3 feet off the deck is NOT a proficiency I feel the need to gather.  

OK, from this 30 year flight instructor, I will.  But who said you should take off in marginal conditions as determined by doing a proper preflight including a review of the POH?  If you are going to takeoff from a high DA airport you want the greatest margin of safety, and that means flying in ground effect as close to the ground as possible to get the maximum reduction in induced drag to get the maximum performance from the plane, especially a non turbocharged airplane.

[MikeOH]

Well, golly gee. I guess as a child of a lesser god I should just bow down to a 30 year master CFI. Never question authority, right?

Not a chance I’m going to just for being more conservative in my approach at a high DA airport. I put a buffer on the POH numbers, operate well below gross and stay within a wingspan. I am not going to check my prop clearance by flying 3 feet down a runway!

Your argument is bit specious as it hinges on what is high DA…otherwise you’d have us all flying at 3 feet to achieve “the greatest margin of safety” on all take offs.

[cliffy]

IF the numbers the OP wants are not readily available one can always  look at a Koch Chart and estimate

what the runway length and climb rate might be to a high degree of accuracy (working from sea level numbers) (Google it)

As one who was required to fly the length of T&T runway (west of MIA) at less than 10 feet! (gear and flaps 30) when I checked out in the 727-

Yes it can be done even at less than 10 feet but to what avail is it REALLY NECESSARY for the average pilot? 

As for me - after more than 60 years in this flying business I find my NEED to push the limits just ain't there anymore. 

Trust when I say if you haven't been to the edge you REALLY don't want to go there. It ain't fun by any means!

Machismo has no place in flying- period! End of sermon.  

A  truism- ALL accidents are investigated the next day when the weather is usually ALWAYS better!

 

[donkaye]

49 minutes ago, MikeOH said:

Well, golly gee. I guess as a child of a lesser god I should just bow down to a 30 year master CFI. Never question authority, right?

I don't know, I try to keep and open mind and learn from others, especially those who might have more experience that I do. 

 

[donkaye]

1 hour ago, MikeOH said:

Your argument is bit specious as it hinges on what is high DA…otherwise you’d have us all flying at 3 feet to achieve “the greatest margin of safety” on all take offs.

Personally, I do accelerate to 5 knots below Vx on most takeoffs before I climb out.  It happens rapidly in the M20M.  I hit Vx on the climb.

[MikeOH]

14 minutes ago, donkaye said:

I don't know, I try to keep and open mind and learn from others, especially those who might have more experience that I do. 

 

You might practice what you preach and read the post above yours, from Cliffy.

[MikeOH]

9 minutes ago, donkaye said:

Personally, I do accelerate to 5 knots below Vx on most takeoffs before I climb out.  It happens rapidly in the M20M.  I hit Vx on the climb.

As do I, .... just not 3 feet above the runway!

[donkaye]

1 hour ago, cliffy said:

IF the numbers the OP wants are not readily available one can always  look at a Koch Chart and estimate

what the runway length and climb rate might be to a high degree of accuracy (working from sea level numbers) (Google it)

As one who was required to fly the length of T&T runway (west of MIA) at less than 10 feet! (gear and flaps 30) when I checked out in the 727-

Yes it can be done even at less than 10 feet but to what avail is it REALLY NECESSARY for the average pilot? 

As for me - after more than 60 years in this flying business I find my NEED to push the limits just ain't there anymore. 

Trust when I say if you haven't been to the edge you REALLY don't want to go there. It ain't fun by any means!

Machismo has no place in flying- period! End of sermon.  

A  truism- ALL accidents are investigated the next day when the weather is usually ALWAYS better!

 

Well, I bow to Cliffy with 60 years of flying.  I only have 56 years, having gotten my Private in 1968.  I agree with most of what he says.  I don't advocate flying on the edge, just using good piloting technique as conditions demand.  Using ground effect to your benefit is one of them, both in takeoff AND landing.  While it's of real benefit in takeoff, when it comes to landing the Mooney it can create problems in judging rate of energy dissipation.