Leadville (KLXV) in an NA Mooney?

[Ragsf15e]

21 minutes ago, Shadrach said:

according to the NTSB the DA was 4100'.  The aircraft was TN'd and was making >90% horsepower throughout the sequence. He was 100lbs over gross. NTSB blamed it on a "wind shift" and the extra 100lbs.  Maybe...but to me it looked like his pitch attitude put him behind the power curve about a wingspan above the ground. 

Wasn’t his gear down for that whole video?  Seems like a lot of drag could be relatively quickly removed…

[PeteMc]

8 hours ago, N201MKTurbo said:

Why would anybody try to climb out of ground effects before you had enough airspeed?

Did not mean to imply not enough speed, but if I'm reading the discussion correctly, Don is saying to stay in Ground Effect and keep accelerating well after you've reached and acceptable Climb Speed. 

But if I remember my primary training, if you're at your expected speed and you're not climbing/accelerating, then something is wrong and you set down.  You did NOT keep flying down the runway hopping you'd eventually take off.   

Don's procedure is one for a more experienced pilot that sees what's happening and knows if continuing is a good thing or not.  Also, as he pointed out (or someone did) that in a Mooney you'd be right above the Rwy, so not something you just decide to do one day.

 

Edited July 15 by PeteMc

[PT20J]

On 7/13/2024 at 4:37 PM, kortopates said:

Excellent points and especially #4 but nothing wrong with pitching down till the you feel light in the seat. This is after all what the upset recovery schools teach these days and the ACS no longer makes any statements about minimizing altitude loss. Instead the emphasis is on "immediately recovering from the stall by reducing the angle of attack". 

No matter how bad a wing might be dropping off in the stall, an immediate push down that makes you light in the seat will very promptly recover back to flying speed with wings leveled and the pilot can transition back to climb attitude to return to the starting altitude. 

So personally I think its a big confidence booster for those fearful of power on stalls - which is required to the full break these day for private students and whichever the DPE calls for on the Commercial. 

The other reason for pushing till light in the seat is that folks where focusing on preserving altitude to only get into a secondary stall; usually more violent than the first.

Unloading until light in the seat is a good habit to form because it prevents the biggest spin risk which is a secondary stall from an ineffective recovery attempt. 

[PT20J]

2 hours ago, BlueSky247 said:

Funny timing. I just happened to catch an interesting YT last night where a Baron driver was making an excellent case for delaying rotation by five knots. His argument was that the extra speed not only dramatically improves the climb rate and subsequently, the engine out safety margin but also yields rudder authority should an engine die on rotation. 
 

I’m not suggesting we rotate at 90 knots at Leadville, but that certainly would be one way of staying in ground effect longer. 

Twins are a different beast. Because of Vmc considerations, they are designed to land and takeoff at higher speeds relative to Vs than singles. If you keep a Mooney on the ground too long on takeoff, it will wheelbarrow you into the weeds. The best sustained rate of climb is going to be at Vy. If you accelerate to a higher speed, you can zoom climb for a few hundred feet, but eventually the ROC will decrease.

Bob Hoover’s signature maneuver was a roll on takeoff. If you watch a video you’ll note that he would lift off as soon as possible, level off very close to the runway, retract the gear, accelerate in ground effect to a high speed, pitch up to a steep climb angle and have enough energy to complete an aileron roll.

[Pinecone]

You have to be careful to not take off into ground effect, but still being on the back side of the power curve.  If you do, then you have no choice but to touch down again to lower AoA to accelerate.

Delaying the rotation by 5 or 10 knots puts you on the front of the power curve and allows you to accelerate in ground effect, then climb out.

[Shadrach]

41 minutes ago, Ragsf15e said:

Wasn’t his gear down for that whole video?  Seems like a lot of drag could be relatively quickly removed…

it was. I would have raised the gear, but I don’t think it would have mattered much in his case.  Looked like he was at an above optimal AOA that was masked while in ground effect but became critically obvious as he tried to climb higher than about a wingspan above the ground. Looked like he kept pulling and decelerated mushing back into ground effect and ultimately, the ground. As you know hot and heavy operations require some finesse. 

[N201MKTurbo]

1 hour ago, PeteMc said:

Did not mean to imply not enough speed, but if I'm reading the discussion correctly, Don is saying to stay in Ground Effect and keep accelerating well after you've reached and acceptable Climb Speed. 

But if I remember my primary training, if you're at your expected speed and you're not climbing/accelerating, then something is wrong and you set down.  You did NOT keep flying down the runway hopping you'd eventually take off.   

Don's procedure is one for a more experienced pilot that sees what's happening and knows if continuing is a good thing or not.  Also, as he pointed out (or someone did) that in a Mooney you'd be right above the Rwy, so not something you just decide to do one day.

 

OK, but the Bonanza in the video did try to climb out of ground effects without enough airspeed. 

I think what Don is saying is to essentially do a soft field takeoff where you get the airplane off the ground as soon as you can, then accelerate in ground effects until you have climb speed, then start your climb. Once you are established in ground effects, it isn't an issue to wait a bit until you climb out. You will be accelerating, so the airplane will require continuously increasing forward pressure on the yoke to maintain altitude.

[PeteMc]

39 minutes ago, N201MKTurbo said:

I think what Don is saying is to essentially do a soft field takeoff where you get the airplane off the ground as soon as you can, then accelerate in ground effects until you have climb speed, then start your climb.

Right, that's how I understood it.  And for me from the normal Rotation (64) to Vx (68) would be nothing.  But I can get the plane up into Ground Effect a little earlier.  And it's more of a feel than it is a fixed number.  But once up, I could see acceleration to Vy over a long runway without any obstacles.  I haven't done the math, but my guess at Leadville I'd start the climb in the 88 KIAS range (83 @ 15K).  And assuming I'm meeting all the climb requirements (again, haven't done the math), I'd rather climb at Vy with the nose down a bit more for cooling. 

[Pinecone]

14 hours ago, N201MKTurbo said:

OK, but the Bonanza in the video did try to climb out of ground effects without enough airspeed. 

I think what Don is saying is to essentially do a soft field takeoff where you get the airplane off the ground as soon as you can, then accelerate in ground effects until you have climb speed, then start your climb. Once you are established in ground effects, it isn't an issue to wait a bit until you climb out. You will be accelerating, so the airplane will require continuously increasing forward pressure on the yoke to maintain altitude.

The problem with off as soon as you can is, you can be off the ground, but once you climb a few feet, the lower ground effect is just enough to keep you flying, but high drag keeps you from accelerating.

[Shadrach]

2 hours ago, Pinecone said:

The problem with off as soon as you can is, you can be off the ground, but once you climb a few feet, the lower ground effect is just enough to keep you flying, but high drag keeps you from accelerating

 

If by a few feet you mean 30 to 40, then I agree. If you mean 3 to 5 feet then I disagree. The whole point of staying in ground effect is to benefit from the increase in lift and the muting of induced drag when flying near the runway. This corresponds to a reduction in the AOA  required for level flight while in ground effect and allows more of the aircraft’s energy to be devoted to accelerating. It’s pretty clear that the Bonanza in the video attains an AOA that was adequate for liftoff in ground effect but was increasingly inadequate with every foot of additional altitude. Rather than lower the nose, he ignores the first rule of holes and elects to keep shoveling.

[MikeOH]

No, he ignored the FIRST rule: Take offs are optional

[Shadrach]

40 minutes ago, MikeOH said:

No, he ignored the FIRST rule: Take offs are optional.

indeed and two unsuspecting passenger lost their lives because of it. NTSB made no mention of the uphill takeoff. The departure end of the runway is 20’ higher than the approach end. The report says film showed the wind sock was totally limp when he departed.

the only reason this wasn’t worse was because the stall was muted by ground effect. If it had happened at 300ft agl, the break would have been much more violent.

[MikeOH]

22 minutes ago, Shadrach said:

the only reason this wasn’t worse ...

Two DEAD passengers!  How much worse could it have been?

[Shadrach]

33 minutes ago, MikeOH said:

Two DEAD passengers!  How much worse could it have been?

Much…Full power, stall break, left wing drop and impact near full nose down…4 dead on board, explosion, fire and potential for ground injuries. 

[Pinecone]

3 hours ago, Shadrach said:

If by a few feet you mean 30 to 40, then I agree. If you mean 3 to 5 feet then I disagree. The whole point of staying in ground effect is to benefit from the increase in lift and the muting of induced drag when flying near the runway. This corresponds to a reduction in the AOA  required for level flight while in ground effect and allows more of the aircraft’s energy to be devoted to accelerating. It’s pretty clear that the Bonanza in the video attains an AOA that was adequate for liftoff in ground effect but was increasingly inadequate with every foot of additional altitude. Rather than lower the nose, he ignores the first rule of holes and elects to keep shoveling.

The problem is, if you try to lift off at minimum airspeed that you can, you are back side of the power curve and depending on the extra lift of ground effect.  So, at that point the only way to accelerate is to go down, and touch down again.

I think it would be better to stay on the ground and accelerate, like a short field take off.  At least to get to the proper side of the drag/power curve.

[donkaye]

To be clear, I never advocated doing a soft field takeoff from a high density altitude airport.  In fact I don't advocate landing on grass fields, although a number of people live on airparks and do land on them with Mooneys.  The risk level goes up due to minimal prop clearance.  I'd actually recommend doing a short field takeoff from a place like Leadville.  Achieve full power for the altitude before brake release.   Still, I'd recommend staying in ground effect until Vx before climbing out.

Practicing soft field technique is used to better understand the aircraft envelope to help prevent LOC accidents on the ground or on a go around.

[Shadrach]

33 minutes ago, Pinecone said:

The problem is, if you try to lift off at minimum airspeed that you can, you are back side of the power curve and depending on the extra lift of ground effect.  So, at that point the only way to accelerate is to go down, and touch down again.

I think it would be better to stay on the ground and accelerate, like a short field take off.  At least to get to the proper side of the drag/power curve.

I have never heard or read any one advocate for yanking the aircraft off the ground at the ragged edge. I was taught to  raise the nose enough to take the weight off the nose wheel when the airplane lifted off, level to neutral pitch and accelerate.

Over the years I’ve done a lot of soft field practice in a variety of aircraft including some very low powered machines.  Never has it resulted in a situation where I’m mushing down the runway, hanging on the prop, not accelerating. 

[PeteMc]

33 minutes ago, donkaye said:

In fact I don't advocate landing on grass fields

I've landed a few times at Basin Harbor, VT (B06).  But then the Runway was maintained by the Golf Course Grounds Keeper.  So you did get to land basically on a fairway.  

I've also landed at Cavanaugh Bay, ID (66S).  That Apt is also well known to me and generally in excellent condition.  BUT the grass is kept fairly long and is a tougher type of grass that B06's fairway.  So I had the inner gear doors removed at a shop in Spokane before I flew up there for a few days.  On a side note, that Rwy is also on a slope and I don't know the elevation change, but I only landed 15 and departed 33.

[PeteMc]

44 minutes ago, Shadrach said:

I have never heard or read any one advocate for yanking the aircraft off the ground at the ragged edge.

I was never taught to YANK the aircraft off.  But I was taught that sometimes you can get some suction/stiction on a wet wet grass/soft field and you'll be at flying speed, but not lifting off.  So a quick smooth pop with the yoke and then getting the nose back down will break that bond a little quicker.  Sure, if the field is long enough you will eventually accelerate to where you break free, but this got you in the air and then more like Don was describing, accelerating even more and then you'd start your climb. 

 

[Shadrach]

4 minutes ago, PeteMc said:

I was never taught to YANK the aircraft off.  But I was taught that sometimes you can get some suction/stiction on a wet wet grass/soft field and you'll be at flying speed, but not lifting off.  So a quick smooth pop with the yoke and then getting the nose back down will break that bond a little quicker.  Sure, if the field is long enough you will eventually accelerate to where you break free, but this got you in the air and then more like Don was describing, accelerating even more and then you'd start your climb. 

 

my point was I was never taught to lift off at a speed in which I could not level off in Ground effect

[dkkim73]

Well, so let's take this conversation in a natural direction. What determines Vr? I'm having good results with Vr=55 and aim for liftoff at 77 KIAS. 

[PT20J]

35 minutes ago, dkkim73 said:

Well, so let's take this conversation in a natural direction. What determines Vr? I'm having good results with Vr=55 and aim for liftoff at 77 KIAS. 

Well, now you've opened a can of worms  Technically, VR is a jet thing: VR is the speed at which rotation can be initiated at the appropriate rate of about 3° per second. VR ensures that V2 is reached at 35 feet above the runway surface at the latest, including in the event of an engine failure.

The term has crept into piston ops. The FAA defines it in Part 23 simply as: VR is the speed at which the pilot makes a control input, with the intention of lifting the airplane out of contact with the runway or water surface.

In reality, it is superfluous. If you really wanted to use a VR, it would need to be calculated based on weight. But, the best way to take off in a piston airplane (that has less thrust and accelerates much more slowly than a jet) is to apply some back elevator at the beginning of the takeoff roll and let the airplane fly off naturally when it's ready.

[PT20J]

It is certainly possible to attempt a takeoff at a density altitude so high that the airplane will not have enough power to climb out of ground effect.

But, I don't believe it's because the airplane is on the backside of the power curve and holding it on the runway for a few extra knots won't help. As Ross @Shadrach pointed out, the induced drag is much lower in ground effect because the upwash, downwash and tip vortices are reduced by the ground's effect on airflow around the wing. The so called back side of the power curve exists where induced drag predominates. But in ground effect, the induced drag is lowered and thus the region of reverse command, or back side of the power curve, occurs at so low an airspeed that it may be negligible. Once airborne, the airplane will accelerate in the low drag region of ground effect until attaining Vy, and if there is enough excess power to permit a climb at Vy, it can climb. 

[Shadrach]

8 hours ago, dkkim73 said:

Well, so let's take this conversation in a natural direction. What determines Vr? I'm having good results with Vr=55 and aim for liftoff at 77 KIAS. 

I don’t use a speed. I (more or less) use a constant pitch input. The airplane lifts off when the airflow is sufficient for flight at the current weight.

[dkkim73]

3 hours ago, Shadrach said:

I don’t use a speed. I (more or less) use a constant pitch input. The airplane lifts off when the airflow is sufficient for flight at the current weight.

Hi Ross, 

Do you mean a constant pitch attitude? (more elevator early, then less later, maintain attitude to lift-off)

Or constant subjective amount of elevator, which would resulting in progressive lightening of the nosewheel and eventual rotation and lift-off? 

I suppose there is more drag at higher AOA, though @PT20J pointed out that induced drag is dominant here, and greatly reduced by ground effect (which we are in while rolling). And having the nosewheel off, or at least light, reduces wheelbarrowing. 

David

PS. Coincidentally, the scenario discussion for the Pilot Workshops newsletter (received just this morning) touches on several of these topics (Leadville, how to manage potentially not enough energy for climb-out, etc): https://pilotworkshop.com/tips/calculating-takeoff-and-landing-distance/