I owe my life to my CFI.

[Richard]

I had a failry savvy sailplane pilot tell the that when clearance of an obstacle is in doubt I should aim at the top of the obstacle. If while doing so the airspeed climbs above Vx (or Vy) I have beau coup excess energy available. OTOH, if the airspeed bleeds below Vx the aircraft will not clear the obstacle, no how, no way, and it is time to make another plan--quickly.

What scenario would justify that?



Note: I highlighted the words that make me think Ed knows Japanese and French.

 

[Skip Miller]

I had a failry savvy sailplane pilot tell the that when clearance of an obstacle is in doubt I should aim at the top of the obstacle. If while doing so the airspeed climbs above Vx (or Vy) I have beau coup excess energy available.

Then the problem becomes when to start the zoom to clear the obstacle. That's not a maneuver most of us practice very often.... However, if you find yourself in that situation, it may be a better option than taking the forced landing/crash that is the alternative.

-Skip

 

[Dave Siciliano]

There's been a very interesting discussion of the on the Bonanza board at the same time. Great reading.
Last weekedn a Bo went down in Utah. Current thinking (while waiting for the accident report) is it was a high airport with high DA. A storm system was approaching and as he departed, there was a large wind shift. So, if the plane is climbing slowly to begin with, and there is a major shift in winds where are fairly high, what does one do!

Several stories have come out about high DA departures in heavy planes. What has become apparent, is some pilots had now idea how the AC performance was affected. One took off in a Debanair with a DA or 11,000 feet, full full (including tips) and passengers. The pilot was asking why performace was so poor!! The service ceiling on this plane was low teens before tips were added.

I'm thankful for turbos, but high DA still affects my plane.

Great discussion!

Best,

Dave

 

[Dave Siciliano]

I don't believe I mentioned that I took a lesson with a BPPP instructor before departing for my Summer trip to Cozumel, Mexico.

One of the first things he did was discuss pressure altitude and performance; how to calculate DA. I was perplexed as all my flying is to longer runways, but it was eye opening! We did several calculations of takeoff roll and climb. One airport I use in Wisconsin is 4,000 feet with power lines off the south departure. It clearly showed there wasn't much room for things to go wrong on a hot day if the plane is heavy (usually full fuel out of there for a long trip).

With the turbos, I can make full power higher, but it still takes a longer takeoff roll and climb is affected. When one starts to run lean of peak, temperature changes can make a big difference in the power setting if one is trying to keep CHTs at 380 or less.

Best,

Dave

 

[Dave Krall CFII]

There's been a very interesting discussion of the on the Bonanza board at the same time. Great reading.
Last weekedn a Bo went down in Utah. Current thinking (while waiting for the accident report) is it was a high airport with high DA. A storm system was approaching and as he departed, there was a large wind shift. So, if the plane is climbing slowly to begin with, and there is a major shift in winds where are fairly high, what does one do!

Several stories have come out about high DA departures in heavy planes. What has become apparent, is some pilots had now idea how the AC performance was affected. One took off in a Debanair with a DA or 11,000 feet, full full (including tips) and passengers. The pilot was asking why performace was so poor!! The service ceiling on this plane was low teens before tips were added.

I'm thankful for turbos, but high DA still affects my plane.

Great discussion!

Best,

Dave

Just curious, did anyone check the Debonair pilot to see if he'd ever taken the FAA private pilot tests ?

 

[Ed Guthrie]

Then the problem becomes when to start the zoom to clear the obstacle.

I believe you mis-read the description. Aim at the very top of the obstacle. IOW, aim to just barely clear it. No zoom needed. You either achieve a suitable climb speed with that aim point or you need another plan.

 

[Dave Siciliano]

Just curious, did anyone check the Debonair pilot to see if he'd ever taken the FAA private pilot tests ?

Actually Dave, the tone is much gentler on that board. It leads to many more folks admitting they don't know something and provides a better learning environment. Sounds pretty basic to me, but was a flat land pilot that just hadn't encountered that set of conditions before. (Seems to occur a lot when Osh Kosh beckons!!).

Several folks pointed out the same issues we've been discussing. Good refresher for all; awakening for him.

Best,

Dave

 

[Dave Krall CFII]

Actually Dave, the tone is much gentler on that board. It leads to many more folks admitting they don't know something and provides a better learning environment. Sounds pretty basic to me, but was a flat land pilot that just hadn't encountered that set of conditions before. (Seems to occur a lot when Osh Kosh beckons!!).

Several folks pointed out the same issues we've been discussing. Good refresher for all; awakening for him.

Best,

Dave

Yes Dave, I was being purposefully gentler of tone as well...

Flatlander or not, experienced or not, encountered that set of conditions before or not, I wish that type of pilot that either ignores or forgets about the very basics of flying that he was tested on could be either suitably re-trained or stripped of his license. He is a big part of the mood of public and governmental discrimination agaist all pilots that we're all paying for and enduring.

DJK

 

[Dave Siciliano]

I am sometimes very surprised by what some long time pilots don't know; yet, as I gain in experience, I realize there is sooo much to know. To you this is fundamental and the pilot should be punished. We are all frustrated with those that bring flying a bad name unnecessarily.

I wonder how knowledgeable an expert pilot would seem to an expert mechanic when digging into engine details; How expert the mechanic would seem to the engineer that designed and produced the engine; the engineer to the physicist that understands the theory behind how it works.

We all strive to be experts; we can only do that within a very narrowly defined band of knowledge. Sometimes it's pretty overwhelming to me when I think about it.

I do completely understand your point; this is pretty fundamental. Yet, to a farmer, common sense and basic knowledge is something completely different than to a urbanite.

I'm pretty direct most of the time, but sometimes the directness and criticism don't assist someone else in learning.

While I'm at it, a toast to the teachers--David; Ron, Bruce and Terry (and the other CFIs on here along with those that teach our children):

To the teacher!! One who gives up a life of means for one of meaning

Best,

Dave

 

[Dave Krall CFII]

I am sometimes very surprised by what some long time pilots don't know; yet, as I gain in experience, I realize there is sooo much to know. To you this is fundamental and the pilot should be punished. We are all frustrated with those that bring flying a bad name unnecessarily.

I wonder how knowledgeable an expert pilot would seem to an expert mechanic when digging into engine details; How expert the mechanic would seem to the engineer that designed and produced the engine; the engineer to the physicist that understands the theory behind how it works.

We all strive to be experts; we can only do that within a very narrowly defined band of knowledge. Sometimes it's pretty overwhelming to me when I think about it.

I do completely understand your point; this is pretty fundamental. Yet, to a farmer, common sense and basic knowledge is something completely different than to a urbanite.

I'm pretty direct most of the time, but sometimes the directness and criticism don't assist someone else in learning.

While I'm at it, a toast to the teachers--David; Ron, Bruce and Terry (and the other CFIs on herea long with those that teach our children):

To the teacher!! One who gives up a life of means for one of meaning

Best,

Dave

This particular issue is so simple that expert ability is not required ( passing FAA testing also shows basic knowledge was imparted ) and becomes therefore more a matter of deficiencies in basic judgements of decision making which is perhaps even more dangerous than ignorance or lack of ability.

First offense: hopefully the costs of damages inflicted to the PIC and other losses will be punishment enough.

Second offense: throw the book at them and get them out of the sky, for everybody's good.

 

[bbchien]

This particular issue is so simple that expert ability is not required

What is needed here is not technical expertise. The test pilots gave that to us. The PTS gives us a base level.

What is needed is judgement. That ephemeral thing that distinguishes Aviatiors from pilots.

"Sorry folks, here's the keys to the Ford, meet me over at the BIG airport six miles down the road...."

 

[Dave Siciliano]

I don't know this pilot well. It is apparent he's been flying a long time from his posts. He had a B-33 Bonanza and in this case was flying a Debonair with the 225 HP engine (which is not a great performer when full to begin with). It's also apparent, he didn't fly in the mountains a lot. On the way to OSH, he hit headwinds and did determine that he needed to stop for full before he had planned. When he did stop, it was at a higher elevation airport in the afternoon. He had planned to stop at a lower elevation airport with a longer runway.

He now freely admits to making several errors: When he refueled, he filled the tanks--including tips. He now states, he shouldn't have put full fuel in on that airport with that DA. When he departed, he did not consult the POH regarding the effect of DA on the departure. When he did depart, he did not lean as much as he could have (his words). Also, he did not fly at Vy, he did about 15 knots faster (according to him).
His bringing this out has lead to a lot of very positive discussion and he has quickly grasped the error of his ways. I think it's also caused a lot of others folks to focus on this. Folks have made many suggestions to him including attending a mountain flying course. He has dug into the books and freely admitted his error. As a matter of fact, he brought each of the above out.

Not taking his side or stating he wasn't in error to begin with, but the outcome to his making this post has been very positive IMHO. He continues to dialouge. In many cases, when folks become confrontational or accusatory, the poster becomes emotional or quits posting. I'm pleased to see things evolve in this manner.

I've done some things I'm not proud of and had some folks jump all over me when I brought them up. Guess I just look at this differently. If it's wrong, on not good technique, I sure try to point it out; just try to coach instead of confront.

Dave

 

[mgkdrgn]

As my CFI told me "You can trade airspeed for altitude, but you must first have something to trade. If you want to clear something tall and nasty at the end of the runway, the first step is to point the airplane directly at it ..."

As you do, I hear that in the back of my head every takeoff I make. Of course, the fact that the "home" field is 2300' with 50' trees on all 4 sides might have something to do with that too ... (think reverse mohawk haircut into the trees). ;-)

 

[Dave Krall CFII]

I don't know this pilot well. It is apparent he's been flying a long time from his posts. He had a B-33 Bonanza and in this case was flying a Debonair with the 225 HP engine (which is not a great performer when full to begin with). It's also apparent, he didn't fly in the mountains a lot. On the way to OSH, he hit headwinds and did determine that he needed to stop for full before he had planned. When he did stop, it was at a higher elevation airport in the afternoon. He had planned to stop at a lower elevation airport with a longer runway.

He now freely admits to making several errors: When he refueled, he filled the tanks--including tips. He now states, he shouldn't have put full fuel in on that airport with that DA. When he departed, he did not consult the POH regarding the effect of DA on the departure. When he did depart, he did not lean as much as he could have (his words). Also, he did not fly at Vy, he did about 15 knots faster (according to him).
His bringing this out has lead to a lot of very positive discussion and he has quickly grasped the error of his ways. I think it's also caused a lot of others folks to focus on this. Folks have made many suggestions to him including attending a mountain flying course. He has dug into the books and freely admitted his error. As a matter of fact, he brought each of the above out.

Not taking his side or stating he wasn't in error to begin with, but the outcome to his making this post has been very positive IMHO. He continues to dialouge. In many cases, when folks become confrontational or accusatory, the poster becomes emotional or quits posting. I'm pleased to see things evolve in this manner.

I've done some things I'm not proud of and had some folks jump all over me when I brought them up. Guess I just look at this differently. If it's wrong, on not good technique, I sure try to point it out; just try to coach instead of confront.

Dave

In this case he MAY have subsequently RE-learned some things sufficiently for future, safe application in flight due to his very lucky, expensive, and dangerous accident caused by a lackadaisical attitude, combined liberally with poor judgement and stupidity and ultimately paid for by most of us other pilots in many ways we can ill afford at this time.

All of it is academic.

 

[pete177]

Hmm..lets see, where's that manual.

5000ft, 80degrees f, gross 2575lb (3 adults, 5 hours fuel, 50lb baggage), ground roll 1330ft, 2270 over 50ft, roc 720fpm.

sea level, 59 dg, 2200 lb, ground roll 575, 1000ft over 50ft, roc 1400fpm
150 knots at reasonable cruise setting
Mooney M20E 200HP
Why would anyone buy a cherokee?
Hershey bars are for eating, not flying

 

[gismo]

Keep in mind that lowering the nose to pick up speed above Vy while maintaining a flight path that clears the obstacle actually increases your total energy budget with a fixed pitch prop. Remember that total energy equals potential (weight times height) plus kinetic (1/2 mass times velocity squared). Extra speed lowers prop drag, allowing the engine to spin up to a higher RPM and generate more power. Even with a CS prop, the increased airspeed at full power allows the prop to take a deeper bite of the air at the same RPM.

True, you won't clear the obstacle by as much as if you flew Vy all the way, but your TOTAL energy (kinetic plus potential) will be higher when you get to that point over the ground, leaving you more options if the engine quits at that point, the extra kinetic energy being convertible into more potential energy by zooming for altitude.

I can see the possibility to gain total energy by going faster than Vy with a fixed pitch prop (as you say, the power output of the engine will increase with the RPM), but it seems at least as likely to decrease the total energy gain with a C/S prop. As one exceeds Vy, parasite (and to a slightly lesser extent total) drag builds rapidly with speed and since drag * velocity = power lost to overcoming the drag, the power required for level flight is eating up a lot of what woujld otherwise become part of the total energy.

It would be interesting to compute and plot TE after flying a couple miles at different airspeeds vs the speed flown to see what speed would give the moximum TE for a few different planes (some C/S and some fixed pitch).

 

[gismo]

That would explain why you often saw underpowered planes fly straight for the trees, pull up, and drop back down to disappear, only to reappear above the next row. Repeat as required until adequate climb speed can be maintained. "Hedge hopping", I think they called it.

Actually (IMO) the idea behind that techniqe is to use the more efficient flight in ground effect between the hedges to gain enough total energy to clear the next hedge.

 

[Richard]

I can see the possibility to gain total energy by going faster than Vy with a fixed pitch prop (as you say, the power output of the engine will increase with the RPM), but it seems at least as likely to decrease the total energy gain with a C/S prop. As one exceeds Vy, parasite (and to a slightly lesser extent total) drag builds rapidly with speed and since drag * velocity = power lost to overcoming the drag, the power required for level flight is eating up a lot of what woujld otherwise become part of the total energy.

It would be interesting to compute and plot TE after flying a couple miles at different airspeeds vs the speed flown to see what speed would give the moximum TE for a few different planes (some C/S and some fixed pitch).

Well, I'll tell you one thing, a high G pitch up would likely result in looking up at the bushes. That is, unless you have adequate clearance to descend after clearing the obstacle. It would be interesting to plot how much clearance is adequate clearance vis a vis G load in the pitch.

 

[Richard]

Actually (IMO) the idea behind that techniqe is to use the more efficient flight in ground effect between the hedges to gain enough total energy to clear the next hedge.

None other than Lindbergh used this technique to successfully launch his flight into history. It wasn't his desire to descend after barely clearing the trees. In fact, most observers thought he had crashed and were greatly relieved to see him clear the next row of trees.

Other than being severely over gross for a record attempt I cannot see a good reason why a pilot would knowingly put himself in this corner of the box.

 

[Dave Krall CFII]

Well, I'll tell you one thing, a high G pitch up would likely result in looking up at the bushes. That is, unless you have adequate clearance to descend after clearing the obstacle. It would be interesting to plot how much clearance is adequate clearance vis a vis G load in the pitch.

It was part of the first few lessons my Dad took in a Cub in the 1950s to pitch-up over a hedge row or row of 50 foot+ tall trees & stall/mush down to the ground, bounce a bit with power on off the springy main gear and do the same in succession through the fields and hedgerows.

 

[Ed Guthrie]

Actually (IMO) the idea behind that techniqe is to use the more efficient flight in ground effect between the hedges to gain enough total energy to clear the next hedge.

Yep. BTDT. Chiloquin State Park airport and a Taylorcraft BC12D after a sudden wind shift left me with zip for options. Popped the trees and power line and dropped to the river for ground effect.

 

[Richard]

It was part of the first few lessons my Dad took in a Cub in the 1950s to pitch-up over a hedge row or row of 50 foot+ tall trees & stall/mush down to the ground, bounce a bit with power on off the springy main gear and do the same in succession through the fields and hedgerows.

Reading that gives me the heebie jeebies. But you remind me of watching my friend's father do just that very thing, except not as high as FAA-approved trees. It was the funniest damn thing you ever saw, even though you just 'knew' he was gonna' ball it up. Unplowed cow field cross fenced every coupla' hundred feet with a ditch crossing right down the middle at the start of his roll. He's in his lil 'ol Airknocker with an engine block and associated parts as cargo. He lights it up and about mid way he pitches up--as my stomach sinks like a stone--clears the 1st fence, mushes in, bounces into ground effect, pitches up to clear the 2nd fence never really flying, just mushing along....and so on over 2 more fences until he drops out of sight off the 50' bluff at the ocean's edge. So help me God, there's 'ol Bob skimming the watery deck until he gets enough juice to carry him up and away. He comes back over us and yells out he's good to go and heads off for his destination.

As reckless as he seemed to be the man was an honest to God seat of your pants engineer. You can bet he calculated his minimum required performance. He had over 50 patents, he hand built 11 planes, his engines are spread throughout the 5 western states, among many other things, he designed and built race engines, no use for blueprints. Barney Oldfield won many of his races with Bob's engines.

He passed away two weeks ago an old man. He'd have lived another 400 years in it weren't for the cancer.

He also taught me a trick for getting a tail wheel out of a too short field. Years later Sparky Imeson mentioned the same technique. Start your roll heading about 135* opposite to your intended departure path. Get up some speed and start to circle 'round through 180* all the while gaining speed and once aligned with your departure raise the tail and up an away you go. No, I haven't tried it.

Okay, I'm finished with my thread creep.

 

[Dave Krall CFII]

Reading that gives me the heebie jeebies. But you remind me of watching my friend's father do just that very thing, except not as high as FAA-approved trees. It was the funniest damn thing you ever saw, even though you just 'knew' he was gonna' ball it up. Unplowed cow field cross fenced every coupla' hundred feet with a ditch crossing right down the middle at the start of his roll. He's in his lil 'ol Airknocker with an engine block and associated parts as cargo. He lights it up and about mid way he pitches up--as my stomach sinks like a stone--clears the 1st fence, mushes in, bounces into ground effect, pitches up to clear the 2nd fence never really flying, just mushing along....and so on over 2 more fences until he drops out of sight off the 50' bluff at the ocean's edge. So help me God, there's 'ol Bob skimming the watery deck until he gets enough juice to carry him up and away. He comes back over us and yells out he's good to go and heads off for his destination.

As reckless as he seemed to be the man was an honest to God seat of your pants engineer. You can bet he calculated his minimum required performance. He had over 50 patents, he hand built 11 planes, his engines are spread throughout the 5 western states, among many other things, he designed and built race engines, no use for blueprints. Barney Oldfield won many of his races with Bob's engines.

He passed away two weeks ago an old man. He'd have lived another 400 years in it weren't for the cancer.

He also taught me a trick for getting a tail wheel out of a too short field. Years later Sparky Imeson mentioned the same technique. Start your roll heading about 135* opposite to your intended departure path. Get up some speed and start to circle 'round through 180* all the while gaining speed and once aligned with your departure raise the tail and up an away you go. No, I haven't tried it.

Okay, I'm finished with my thread creep.

Thread creep ? Perhaps not...

These aircraft performance anecdotes show what keeping the nose of the airplane in the right attitude at the right time can accomplish in the hands of a skilled pilot that's on top of the game (throughout a long lifetime) and what can happen otherwise.

 

[Ande Elkins]

Wow, and to think, I've been avoiding flying my C-150 out of my 2000' turf field at DA 2000+ because the trees at the end looked plane-hungry.
I'm at near SL (093') but, I noticed that with me, and my son, aboard 'Eleanor', she tends to be less than spunky on hot days.
Taking of short-field, I always rotate ASAP, and hold ground-effect till 65-70
By-the-way..when I got that plane, he said we should name it.. I was thinking 'Bullet, Speedy, or some other sporty name.. He suggested 'Eleanor'.. I said "that sounds like an old slow woman".. He said "My point exactly"..
So, Eleanor became part of the family..

 

[Richard]

Wow, and to think, I've been avoiding flying my C-150 out of my 2000' turf field at DA 2000+ because the trees at the end looked plane-hungry.
I'm at near SL (093') but, I noticed that with me, and my son, aboard 'Eleanor', she tends to be less than spunky on hot days.
Taking of short-field, I always rotate ASAP, and hold ground-effect till 65-70
By-the-way..when I got that plane, he said we should name it.. I was thinking 'Bullet, Speedy, or some other sporty name.. He suggested 'Eleanor'.. I said "that sounds like an old slow woman".. He said "My point exactly"..
So, Eleanor became part of the family..

A -150 named Eleanor. For some esoteric reason that sounds just so perfect.

Ande, rest assured, most pilots prefer not push their luck on a regular basis. That applies even when their equpment is capable. If you've decided not to do it, the decision has been made. That decision may change further down the road but it's only up to you.

 

[Toby]

This is an incredibly good thread. I've put a lot of time into understanding the points you are all making about DA and AOA, horsepower and airspeed. Thank you, Bruce, Ron, Ed, Dave K., Lance, etc.