Easy or hard to fly? How to define it?

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One of my high school teachers was in the Navy in WWII. He was assigned to the investigation board for an F4U crash.
It seems that it was at night and the pilot of the F4U was in the pattern with a large number of other aircraft, practicing touch and goes. They were flying slowly in a very large pattern in order to accommodate all the aircraft. Flying the whole way with the gear down was noisy and with unpleasant buffeting, so he retracted it. And he flew the F4U into the runway, gear up.

He explained to the board what he had done. They asked why the gear up warning system had not alerted him to the problem.

The pilot replied that the gear warning horn was sounding the whole time he was in the pattern, and that was annoying, so he turned it off. The warning light was still shining and could not be turned off; since it was night that was distracting so he put one of his gloves over it.

And apparently he had unfastened his harness to aid him in looking around for traffic with the canopy open, because when the airplane hit the runway he was valted out of the cockpit, landed in front of the airplane, followed by the engine breaking loose and chasing him down the runway.
 
So, the idea was that the pilot would be able to know what he could do with the plane at any time?

I'm still surprised that some kind of indicator that would widen or narrow to indicate what the maximum usable AoA would be, while displaying the correct AoA.
Can you post a picture of what a standardized aircraft set up versus an older plane so I can get a feel for what you're talking about?
 
I've never seen the AOA indicator the McD engineer was talking about but I believe the "advanced fighter" he was talking about was what we now know as the F15. (this was in 1974) Biff has years of experience in that bird, maybe he could enlighten us. Accurately sensing AOA, like sensing static pressure or ram air velocity in all attitudes and speed regimes is a near impossibility in practical terms. No matter how many sensors you install, or how cleverly you place them, they will always be subject to errors of varying magnitude. Genius comes in minimizing those errors to the greatest extent possible. In addition, an aircraft designed for high G, high AOA maneuvering performance will have certain circumstances under which the flyable AOA range is not the same as in S&L 1G flight. As I understand it the "cockpit AOA" indicates an electronically corrected reading to indicate the AOA range actually available at any given instant. Ask Biff.
Standardization: As our British friend PBehn suggested, USE GOOGLE!! That's what it's there for. There are plenty of good search terms in the original post you quoted. There's tons of information out there, including entire lessons from instrument flying textbooks. They can explain it much more clearly and better illustrated than I can. The internet has all kind of cockpit photographs of aircraft of all ages. Look them up. Better yet, install Microsoft Flight SIM X on your computer and try it out for yourself.
Cheers,
Wes
 
Wes,

The F-15A-D has a "Cockpit AoA Guage" located down on the instrument panel. The two external sensors for it are on each side of the nose, aft of the radome, and are checked to be clean and easy to move.

While I have just shy of 2700 hours in it, I don't know why MacD didn't use "real" AoA. The best AoA sensor in the Eagle was / is the stick actuator. The plane was not balanced between the left and right side, however it was almost not noticeable. However, it did NOT do well with fuel imbalances above a certain amount. I got to the point that i could feel imbalances, or notice them without looking at the fuel gauge. If I put aileron trim in while fighting, something was probably not matched and needed further investigation.

The AoA's we memorized were LRC (long range cruise - same AoA regardless of weight), Max Endurance (same AoA regardless of weight), wet landing AoA, normal pattern and landing AoA, and best acceleration AoA. Actually all those AoA's stayed the same regardless of weight, however speed would very up and down to follow actual aircraft weight. We would also memorize minimum fuel recoveries, which involved climbing to either half our gas was used, or to three times the distance we were out in thousands of feet, slow to Max Range, then do an idle slow speed decent when we hit our glide path.

I never understood why airliners didn't have AoA gauges, instead you have to look up the speeds in tab data for weight & altitude. Or just let the FMC figure it out...

As for standardized instruments, just google the T layout. That is for round dials, and with the advent of glass you can now get a better layout with all the functionality of a HUD on heads down glass. Way cool, way safer, longer between failures.

Wes I flew some T-37's at UPT that had the black ADI. Precessed like mad. Totally sucked. The T-38 had one that looked as big as a basketball after coming out of the Tweet. The Mighty F-4 had a heading scale on their ADI, however they had more switches, buttons, dials, and levers in that cockpit than any one man would know what to do with...

Cheers,
Biff
 
Particularly at high AoA...
In addition, an aircraft designed for high G, high AOA maneuvering performance will have certain circumstances under which the flyable AOA range is not the same as in S&L 1G flight.
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Technically, at different mach numbers the critical AoA will vary to an extent (from what I remember, it has to do with the pressure distribution across the wings). I do remember something about accelerated stalls having counter-intuitive effects owing to flexing of the wings (I think it was mentioned by drgondog)

BiffF15 said:
The F-15A-D has a "Cockpit AoA Guage" located down on the instrument panel. The two external sensors for it are on each side of the nose, aft of the radome, and are checked to be clean and easy to move.
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That layout actually seems fairly straight forward enough (a vane on a disc that can rotate): I still though the F-15 had an AoA indicator on the HUD, something like an alpha symbol with a number indicating degrees. If it's not the F-15, I'm surprised every high performance fighter doesn't have that (it's so elegantly displayed).
While I have just shy of 2700 hours in it, I don't know why MacD didn't use "real" AoA. The best AoA sensor in the Eagle was / is the stick actuator.
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That's good that the shaker's accurate!
The plane was not balanced between the left and right side, however it was almost not noticeable. However, it did NOT do well with fuel imbalances above a certain amount.
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Was the imbalance caused by the right LERX having a gun in it (I figure the airflow would be slightly different), or the fact that the aircraft had a lot of ammo (if I recall right, the F-15A had 940 rounds, and the F-15C had either 940 or 1250 rounds, the latter was stated by a F-15C pilot named Dan Delane who stated this in the following video at 16:45 to 17:00, if it's accurate, which would amount to something like 1126 to 1497 pounds a bit off center).
The AoA's we memorized were LRC (long range cruise - same AoA regardless of weight), Max Endurance (same AoA regardless of weight), wet landing AoA, normal pattern and landing AoA, and best acceleration AoA.
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Is a wet landing like a ditching?
We would also memorize minimum fuel recoveries, which involved climbing to either half our gas was used
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And you'd do this at maximum continuous thrust? This is like a cruise climb right? I remember hearing that this was even done with old commercial airliners (early 1960's before airspace began to clutter up).
or to three times the distance we were out in thousands of feet, slow to Max Range, then do an idle slow speed decent when we hit our glide path.
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So like 15 nm out to 45,000 feet?
I never understood why airliners didn't have AoA gauges, instead you have to look up the speeds in tab data for weight & altitude. Or just let the FMC figure it out...
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I'd figure it'd be more practical for that purpose as the quality for airline pilots vary from excellent (former military pilots, aerobatic pilots, ERAU graduates, crop-duster pilots in no specific order), to average, to less than average.
As for standardized instruments, just google the T layout.
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Oh, I know what you mean -- I thought they had that in the 1920's?
Wes I flew some T-37's at UPT that had the black ADI. Precessed like mad.
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The ADI gyro toppled when you rolled it aggressively? If that happened at night, that could get somebody killed!
That's a big human factors issue -- all the switches should be in places where they can easily be reached and quickly. At least some F-4E's had that later on...
 
Zipper,

The F-15A-D are still flying with their original HUD's circa 1974. They are limited by the symbology generator and are maxed out. If something is put in, something else must come out. We could get AoA in the HUD by selecting a switch that was rarely used, and designed for flying instruments (would bring the ILS or Tacan up into the HUD).

Yes the plane was imbalanced due to the gun, however the ammo was on the centerline (in a drum roughly the size of a 55 gallon barrel). 940 rounds, 3 or 6k rounds per minute selectable, or 100 rounds per second, or 9.5 seconds of continuous trigger. A manly weapon, used to put an exclamation point on the end of "kill", to show your adversary you out flew him and can now lay claim to his widow, dog and pick up... Airflow was different due to the gun port, however only under extreme instances did it rear it's noggin.

Wet landing means a wet runway (most military runways are un-grooved), or stopping distances were short. We could also raise the flaps on landing rollout to increase lift across the horizontal tail enabling an aerobrake to a slower speed (50-60 kias). Just don't let the nose slam down at the end as all your sensitive avionics are in front of the pilot.

If i remember right we could do it in AB, but most guys didn't as it made no difference and it's easier to control fuel flow in military power. As for altitudes we would climb to I think I explained it poorly. If we were a hundred miles out we would climb to 33k, start an idle descent at approx 33 miles no wind aligned with the landing runway (IIRC).

AoA gauges weren't in the toolbox of big airplane designers. I have flown airliners with guys from all backgrounds, and they are basically the same as it's in the interest of the corp to have a standardized group.

The T instrument layout came about after WW2. Look at the cockpits of any WW2 airplane and it's catch as catch can. Hell the early F-16's were laid out badly. Glass has improved it tremendously, plus they have an IFR HUD, something the A-D Eagle doesn't.

The T-37 was designed as a day VFR trainer and morphed into a primary instrument trainer and it's layout was terrible (not a T).

Cheers,
Biff
 
The A-7D had a problem that under some circumstances it could stall and then enter a "post-stall gyration" that was NOT a spin. If the pilot applied normal spin recovery techniques he would never recover.

A private company designed a piece of electronics that would measure both total (including ram) pressure and static pressure and automatically deploy a flap that would enable normal recovery. We were also considering a modified version of that device in the F-106A, where it would replace a device that sensed total versus static pressure and at a raito of about 1.14 automatically transferred fuel to retrim the airplane when it went supersonic. The older mechanical device used in the F-106A was wearing out in the late 70's and we lacked parts to repair it.
 
MIflyer,

The Eagle will spin but is usually easy to avoid (she telegraphs well). There are some rules about where you can't move the stick and when. Follow them and it will keep you out of trouble 96% of the time. Fuel imbalance, flight control problem, or ham fist. Those are the three ways to get into a spin.

We kept the CG aft on our A/B models and they flew very well. The B in particular felt squirrelly and most guys didn't like to fly it. I liked them (we had two) as it would do what i asked (and yes it felt different than the A's). The feel of the jet was affected by the size / shape of the larger canopy. Same fuel, same weapons load, same amount of bullets.

Cheers,
Biff
 
Okay, so the AoA indicator was there, but rarely used...
There is something about a hail of bullets that does spell "The end" particularly well...
Airflow was different due to the gun port, however only under extreme instances did it rear it's noggin.
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That's good
Wet landing means a wet runway (most military runways are un-grooved)
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I didn't know that actually...
We could also raise the flaps on landing rollout to increase lift across the horizontal tail enabling an aerobrake to a slower speed (50-60 kias). Just don't let the nose slam down at the end as all your sensitive avionics are in front of the pilot.
Click to expand...
So, the goal is to kind of know when to hold the nose up, and when to let it come gracefully down?
If i remember right we could do it in AB, but most guys didn't as it made no difference and it's easier to control fuel flow in military power.
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I'd have thought with A/B it'd end up turning into an interception profile (way faster, way higher, and way shorter in range).
As for altitudes we would climb to I think I explained it poorly. If we were a hundred miles out we would climb to 33k, start an idle descent at approx 33 miles no wind aligned with the landing runway (IIRC).
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Oh 1/3 instead of 3/1
AoA gauges weren't in the toolbox of big airplane designers.
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I guess that makes sense, though I've seen some commercial aircraft with HUDs...
I have flown airliners with guys from all backgrounds, and they are basically the same as it's in the interest of the corp to have a standardized group.
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Eh, wouldn't have been the first time I was wrong
The T instrument layout came about after WW2.
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Learn something new every day...
The T-37 was designed as a day VFR trainer and morphed into a primary instrument trainer and it's layout was terrible (not a T).
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Ok, I gotcha...
 
Zipper730 said:
The ADI gyro toppled when you rolled it aggressively? If that happened at night, that could get somebody killed!
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You've got your terms mixed up Zipper. The term is "tumbled" which is what happens when one of those old gyros hits its gimbal limits. They were never intended for use in acrobatic maneuvers, just upright 1G instrument flight. And yes they could and did get people killed. Almost got me. That's why pilots are taught to make "unusual attitude" recoveries using "needle, ball and airspeed", not depending on any attitude or directional gyros.
The precession Biff was talking about is something different. It's the gradual drift away from a correct indication caused by the friction in the gyro's bearings. Google "gyroscopic precession". All gyros are subject to it, but modern ones have correction mechanisms built in.
I almost got killed in the old T-34 by that very phenomenon. I wasn't instrument rated at the time and was flying night VFR over water. Flew right into a cloud I never saw and suddenly realized my rotating beacons were reflecting back at me. "What's this?" "Crap! I'm in a cloud! Where's the horizon? Okay, what did my instructors say? Hands off the stick, and trim it up until altitude and heading are constant. Okay, there's straight and level. Now cage and uncage the attitude gyro. There's your reference. Don't "iron fist" the stick; let the trim fly the airplane. Now once the mag compass settles down, cage the directional gyro, rotate it to the magnetic heading, then uncage it and you're good to go. Fly like you've got robin's eggs between your hands and the stick and between your feet and the rudders. Don't kill any baby robins!
My undoing was the aforementioned gyroscopic precession. As I kept the little "dash-dot-dash" airplane pinned to the horizon line and the wings level, my airspeed started to increase and I was losing altitude. "Huh?? Can't be a graveyard spiral; I'm still on heading." A little back pressure on the stick. "Wow, that feels like Gs! This is starting to get sticky!"
Long story short, I got totally disoriented, never thought to go back to "needle, ball, airspeed" and yanked that poor, long suffering airplane all over the inside of that cloud. We came out the bottom nosedown about 20 degrees, the lights of Marathon tilted across the windscreen at a near-vertical angle, the airspeed near red line and the altimeter unwinding through 800 feet. About the same as what probably happened to JFK Jr. I was flying a 9G airplane. He was not. Landed with 7 1/2 G on the meter. Never forget the reflection of my nav lights in the water.
Cheers,
Wes
 
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I've seen a lot of "these guys are super-human professionals so only absolute performance matters."

The Corsair is a poster child for pilots overcoming design flaws that could have easily been avoided:
  • An cockpit designed so that pilots under about 6 ft tall have to overcome poor visibility control placement, this when average height for white males in the US -- the design demographic -- was about 5 ft 8 in
  • Difficult visibility on approach coupled with poor landing gear dynamics made carrier landings unnecessarily difficult.
  • There was little warning of a stall, especially accelerated stalls; this meant that pilots, especially pilots with little experience in type, could lose control in combat, which was likely to be a lethal error.
Other aircraft had their own flaws, like the fuel tank behind the c/g in some models of P-51, to poor high speed dive behavior of the P-38, to excessive control forces at high speed in the Zero.

Test pilots are supposed to evaluate flying qualities; there's even a scale, but many of the pilots who do the evaluation are employees of the manufacturer, and have some level of conflict of interest. The customer pilots don't have that conflict, but they're also evaluating aircraft just before this expensive, high-profile project is going into production, so there is pressure to pass things that probably shouldn't be accepted.
 
XBe02Drvr said:
You've got your terms mixed up Zipper. The term is "tumbled"
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Okay
They were never intended for use in acrobatic maneuvers, just upright 1G instrument flight. And yes they could and did get people killed. Almost got me.
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Well, I'm glad you lived to tell the tale!
That's why pilots are taught to make "unusual attitude" recoveries using "needle, ball and airspeed", not depending on any attitude or directional gyros.
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Is that using the sideslip/turn indicator, heading and airspeed to orient yourself?
The precession Biff was talking about is something different. It's the gradual drift away from a correct indication caused by the friction in the gyro's bearings.
Click to expand...
How does that get fixed?
Google "gyroscopic precession".
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Basically the gyro is moved 90-degrees in an angle to the direction of force applied to it.
All gyros are subject to it, but modern ones have correction mechanisms built in.
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How does a correction mechanism basically work?
Almost dying does tend to leave an impression!
 

I'm glad, too.

"Needle, ball, and airspeed"= Rate of turn needle, slip/skid ball(part of the same instrument), and your indicated airspeed. In an unusual attitude situation, neither of your heading instruments is reliable. Your magnetic compass is swinging wildly back and forth, and since you're not sure of your attitude, you have to assume your Directional Gyro is tumbled. Besides, you don't care what your heading is at the moment, you just want to stop turning and find straight and level. Your rate of turn needle is your only reliable indication. Likewise, your unusual attitude has probably had you whipsawing the airplane up and down and the lag in your altimeter and vertical speed indicator leave you with stabilizing at cruise speed for your power setting as the best strategy for taming the beast.

Reread my post. The answer is there. It gets fixed by you going to Google or YouTube and exploring a little further. The answer you quoted is straight out of a physics book and doesn't explain what a pilot has to look out for or what to do about it. Dig a little deeper.

There's a Navy training video from the 60's on YouTube that explains gyro precession correction mechanisms way better than I can.

As I flew my trusty T-34 "straight and level" by the attitude and directional gyros, I didn't realize that precession of the attitude gyro was leading me into a very shallow bank with my nose ever so slightly down. Looked like straight and level to me. On top of that my directional gyro was precessing at a similar rate, so as I gradually drifted off heading my gyro was drifting in the opposite direction, so it looked like I was on course. If I had crosschecked with my magnetic compass, I would have realized what was up. I was easing into the dreaded graveyard spiral. Old tired airplane, old tired gyros that were being frequently aerobaticaly abused and not maintained to IFR standards.(it was officially a VFR airplane.) Eventually the spiral got steeper, the airspeed kept increasing, the Gs built up, and I realized something was amiss. Panicked and confused as to the true nature of my problem, I yanked that poor airplane all over the inside of that cloud. Thanks to a solid 9+G airframe, I didn't break it. JFK Jr wasn't so lucky.
Cheers,
Wes
 
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XBe02Drvr,

You are correct that the civilian method of recovering from a unusual attitude is "needle, ball, airspeed", however, the USAF teaches it very differently. I was a T-37 instructor for 4 years and the primary instrument for an unusual attitude recovery was the attitude indicator. The T-37 attitude indicator (ADI) was good for 360 degrees of pitch and roll and although yes, it suffered from precession, it was still accurate enough to perform the recoveries. In fact, as part of their instrument training, students performed Lazy 8's and even an aileron roll while under the hood! This was done to teach the students to rely on their instruments, particularly the ADI. I have been through some pretty wild maneuvers in theT-37 and I've never seen the ADI just lock up- it recovered very fast from spins and other "student maneuvers". For unusual attitudes, we had had the students close their eyes while under the hood (yes, they had a hood that wrapped around their helmet) while we put the aircraft in an unusual attitude. We would then say "recover!" at which point they would open their eyes and perform the recovery. Nose high unusual attitudes required them to increase bank angle up to 90 degrees in order to get the nose down and then roll wings level as they approached the horizon. I also instructed in the T-1 and the same method was used although the students did not wear a hood.

In drifting back to the OP, I would like to add my $.02 if I may. The T-37 was considered to be "easy to fly" and it was. It was very predictable, even at the limit, and had no real vices except that is was underpowered and had slow engine response time. It was very forgiving, even when flying in the buffet near the stall, and you could fly in the pre-stall buffet at will-only using small corrections- to keep the airplane pointed where you wanted to. The airplane talked to you all the time and you could abuse it without worry. However, the T-37 was very difficult to fly precisely. The nose, even in perfectly calm air, yawed constantly back and forth a degree or two. The ADI processed. Engine response time was poor. The airspeed indicator wandered constantly. The instrument panel layout was horrible (Biff is correct that it was originally designed as a VFR-only airplane). The low wing loading meant that every single bump in the hot Texas air was felt. In short, it was a very poor instrument airplane and hard to fly "right on the numbers".

In contrast, the T-38 was very easy to fly precisely. Whatever heading you put it on, it stayed. Whatever pitch attitude you set, it stayed. Great big ADI, nice panel layout, near instantaneous engine response, and very low wing loading meant a very stable platform. But the T-38 required respect near the limits of its operation. At very high altitudes, you had to be very careful with the throttles because you could flame the engines out. It could develop very high sink rates in the landing pattern if you weren't paying attention. It had to be landed on speed in the first 1500 feet of the runway lest you go off the end due to its tiny wheels and tiny brakes. And flying it in the moderate to heavy stall buffet required relatively large and aggressive control inputs to point the airplane where you wanted it. Great airplane, but it required constant diligence.

In short, I think that "handling at the limit" is a big factor (but certainly not the only one) in answering the question of easy or hard to fly.
 
And keeping the person flying it breathing...
I'll take a look: I'm mostly fascinated how later ADI's for aerobatic use became so much more reliable and why bomb-sights designed for jet-powered aircraft seemed to have so many limits (often less than the plane), such as the B-58...
 
DogMD11 said:
very low wing loading meant a very stable platform. But the T-38 required respect near the limits of its operation.
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Huh? How can a fast heavy airplane with '59 Cadillac tail fins for wings have a low wing loading?? Was that supposed to be low wing area? Or high wing loading?
Ah, for the joys of an all-axis 360° no-limits AI! That Korean War vintage T34B had a black and white H-6 style Artificial Horizon with gimbal limits like the blinders on a draft horse. Don't look at it cross-eyed; it'll tumble.
As it was intended as a primary trainer for students who would eventually fly first generation centrifugal compressor jets, it was underpowered and had it's thrustline offset to minimize torque and P-factor effects. It did nice coordinated low energy aerobatics, was intuitive and well balanced on the controls; a joy to fly, but don't try a lomcevak! And it didn't like snap rolls.
Cheers
Wes
 
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Wes,

Rats! I thought I proof-read that better! Yes of course I meant to write "very high wing loading"-- good catch!
Always wanted to fly a T-34; looks like such a fun airplane!

Graeme,

Don't know what the current accident rate for the T-38 is, I'd have to do some research on it. Unfortunately, a T-38 crashed just last week at Laughlin AFB, Texas. One person got out okay but the other was killed. I don't have any more info that that. Sad.

Dog
 
Graeme said:
Does the T-38 safety record from 1972 still stand - or is there a new champion in the USAF?

View attachment 474825
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Graeme,

Interesting report of a 1971 accident rate for the T-38. According to Wiki it was introduced in 1961. They have had inlet mods, two different sets of wings, new ejection seats and a glass cockpit installed w/HUD. Regardless, it flies on today as the advanced trainer for the USAF and several other countries. I would think it's approaching it's mid 50's it would be time for a new trainer...

Cheers,
Biff
 
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