Pilots have a lot of positive comments about airspeed and altitude. Obviously we have to start with airspeed but we get into strong discussions about which is more desirable in various situations. And Wolfgang considers them two means to arrive at the same thing, which is really what is desired : energy or zoom reserve.

John Boyd, in his fairly successful effort to design the perfect fighter, refined this quest for energy maneuverability even further.

While all this was going on, the FAA developed Practical Test Standards that emphasized maintenance of airspeed plus or minus ten knots and altitude plus or minus a hundred feet without ever really explaining the relationship and more safety conscious orientation. While the plus or minus business is very important IFR, the maintaining zoom reserve or energy maneuverability or flying the airplane all the way to the landing is the greater concern in VFR work, especially at low altitude.

So where should our hearts, our belief be? Should we desire and indoctrinate the plus and minus or should we desire and indoctrinate zoom reserve (either in airspeed or altitude), energy maneuverability?

Wolfgang asked us : "What does the airplane want to do:? When we pull back and then let go, when we stall or spin and let go, when we decrease power, When We TURN?
Is the airplane more concerned with the plus or minus numbers or with any attitude that will provide sufficient kinetic energy of pressure airspeed to continue flying?

Some days I like to fly slow over the river, below the trees with Proud Mary in the headsets. It reminds me of my college days when I had no money in the bank. I spent whatever I had very carefully! All pilots should know how to fly like a poor college student!! Extra money in the bank is nice BUT, you may not have it when you need it.
DENNY

Low and slow over the river listening to Proud Mary with no zoom energy is like when we used to have high school sex without a condom. It feels SOOOO good but if anything goes wrong it's going to be costly.

The Air Force is really into high and fast. I think Denny is taking about how poor people fly and enjoy it. Magnum is correct that all the speed we can develop, down low, gives us comfortable zoom reserve.

175 magnum wrote:Low and slow over the river listening to Proud Mary with no zoom energy is like when we used to have high school sex without a condom. It feels SOOOO good but if anything goes wrong it's going to be costly.

Mike

Reminds me of the time Dell flew me to town and back in my 18 for parts. Ex Army helio/prop fixed wing/jet/ and later ag pilot. I was along to sightsee and observe. Low over the braided river for 90 some miles never more than 50' agl and lower most of the time. He'd come to a sharp bend, elevate, skid around wings fairly level, and descend until the next turn. No intercom or Proud Mary to inspire just flying nap of the earth.

He taught a lesson.

Gary

The amount of either kinetic energy of pressure airspeed or potential gravity thrust of altitude necessary to keep the wings of the airplane happy are relative. Physically lift and weight and thrust and drag (man designed and natural ) but pilot orientation is a big factor. What he does with observation orientation mismatch is a big factor.

Contact-

I spent a very large part of my time very low and fast in the Air Force. I'd say 200-500' count as low, and 480 kts+ count as fast. I enjoyed 200', I spent some time at 100' and did not really enjoy that... your focus is a very narrow view right in front of the plane. In this regime there are seconds between good and oblivion. You ain't lived until you use the zoom reserve of 600 kts to climb to 17k' after you've done your low level.

FWIW John Boyd was mostly talking about the maneuverability of one airplane with respect to another. In the Fighter world that is critical. he codified it like NOONE has ever done before.

gunny

The amount of either kinetic energy of pressure airspeed or potential gravity thrust of altitude necessary to keep the wings of the airplane happy are relative. Physically lift and weight and thrust and drag (man designed and natural ) but pilot orientation is a big factor. What he does with observation orientation mismatch is a big factor.

Gunny.

I expect it was intense. I didn't even like the 160 kts of an Air Tractor in the field.

Sorry about the double post. I lose situational awareness often, using smartphone.

Contact-

No worries. I very much like your concept of energy maneuverability and think you are headed in the right direction. But if you would allow me, I think the way you use terminology is confusing. I have to work at it to understand what you are saying, and I am sure others do as well. May I offer some suggestions?

By way of constructive criticism. Kinetic energy is by definition a result of velocity: when you say pressure airspeed it is redundant and confusing. I believe you are referring to the fact in flying that there is True Airspeed, Indicated Airspeed (and CAS) as well as Ground Speed. Ground Speed is irrelevant to how much total energy the airplane actually possesses at any one time. True Airspeed is also nearly irrelevant for very different reasons. Indicated airspeed is the speed of the air over the wing and is totally relevant to kinetic energy. There really isn't a 'pressure' airspeed commonly used in flying. To be more accurate I think the term to be used is indicated airspeed, or just airspeed. Because that is the only speed the vast majority of airplanes can actually present to the pilot and it is a proxy for kinetic energy.

The other suggestion I have concerns Potential Energy. PE is a result of altitude and for sure gravity plays a big part in that. But there is no such thing as gravity thrust. Thrust is a reaction force, felt opposite from, in our case, pushing air behind the airplane via a propeller. Thrust is a result of work. Gravity cannot produce thrust (or at least as we understand and use gravity today, in Star Trek it is different). Gravity plays a part in Potential Energy. Potential Energy derived from altitude is what concerns us in flying and can keep us alive. Total energy on the airplane is the sum of KE+PE.

As for John Boyd's Observe, Orient, Decide, Act loop.... you are spot on about a pilot's orientation being mismatched with reality being the main cause of pilot induced accidents. Reality always eludes us and we have to pursue a truer picture all the time. In other words, Situational Awareness is a transitory state... we are losing SA all the time and it takes WORK to get it back.

Please forgive me, my background required a strict usage of terminology and it is hard for me to do otherwise. I hope I have not offended you.

gunny

Thanks for your post and helpful additions to terminology. I beg to differ however on gravity not producing thrust. Thrust is simply a force; there need not be an opposing reaction as in a jet engine. If gravity did not produce thrust, gliders could never go forward. If you look at the gravity vector, it can be resolved into a force along the flight path and one normal to it. The first of these is thrust and keeps the glider flying forward.

Blue skies,

Tom

Not at all, gunny. I appreciate the clarification and never considered myself an engineer. My only complaint with airspeed is that it has become too much just a number on a gauge. I am trying to get the relative wind makes lift idea.

I avoid talking about the envelope and the edge, etc., because I am actually very conservative. I want my students to understand and use all energy available. Limiting ourselves to just engine power (I think you said was all our thrust ) leaves natural energy under the table. I am not enough physicist to name them correctly but I want my students to understand and use ground effect, gravity, slope, thermal lift, hydraulic lift, and any other I missed. I don't want them on the razors edge. I want them to always be able to find energy sufficient to not just overcome weight and drag but to be able to maneuver.

Keep correcting. Together we can get the idea across. I need an engineering staff. All I have is experience, data, soo much data.

Jim-

I agree.

For me Airspeed is a proxy for energy. Since we don't actually have a gage that can shows us Total Energy we use instruments that measure things we can measure fairly easily. Airspeed and Altitude. Both of those are an approximate of the actual 'thing' we are talking about. For PE, altitude, our height above ground can give us the glide distance (if we remember the glide ratio)... if our engine quit. The difference between stall speed and our cruise speed can define a short list of options if our engine quit. To me the term 'proxy' means a stand in... not 'approximate'. It is a number that is representative of Kinetic or Potential Energy... a stand in for the 'reality' of the airplane energy state.

Folks often blow off the true meaning behind that number. When I was getting my private I made typical wide Cessna patterns. My IP cured me of that by pulling the throttle to idle on downwind and saying my engine quit... he asked me 'Can we make it to the runway?' And the answer was no. I didn't have the kinetic or potential energy to make the glide happen to coincide with the runway. A lesson that has stuck with me.

gunny

In response to low and slow over the river

That's why I have a vesectamy

Over our flight lives most of us spend a relatively small proportion near the ground. Some's because we're concerned about potential component failure, and some's because T/O and landings can be a brief event soon forgotten in the scheme of things.

But how do we practice and perfect those events and especially the sensory inputs that go with each while in or near ground effect?

A long time ago an instructor told me not to land but try to stay close above the runway for several G's but no T's. He then had me fly a river low for a few hours. The point was to get experienced in that realm of flight and learn control and (I see now) some energy maneuverability.

Gary

Magnet wrote:In response to low and slow over the river

That's why I have a vesectamy

Geeeeeese, if you had one, ya oughta be able to spell it.......

MTV

Ha to MTV

Good reason to start out on something like "Word" - weth - spillchacker

Thin cupy hund pasta eet. 2 Bickcuntriepielaughts.hohohum

Also allows you to save the document for further reference etc.


Wawnabrie

Gary, the advantage of spraying is lots of time in ground effect with max airspeed for maneuverability. Crops are generally obstacle free. Short final to touchdown is at constantly changing airspeed and maneuverability. That is why late go around is usually less safe than finding a place to put it down. Rivers are generally crooked with various radius turns making level banked turns problematic. Small radius rudder turns or energy management banked turns don't hit energy maneuverability overload as do regular turns.

Magnet, don't sweat the spelling. I either spell wrong or fail to notice when autospell picks a nonword neither mine nor George Bush's.

wannabe wrote:Thin cupy hund pasta eet. 2 Bickcuntriepielaughts.hohohum


Wawnabrie

You sure you're from Palo Alto bro? Your spelling makes you sound like a Kiwi... https://youtu.be/ZdVHZwI8pcA