Design Flaws in
General Aviation:
tiny windows, contradictory checklists, no
desk, nothing to
drink or eat, no place to go to the bathroom and
sadistic
instructors forcing me to fly in circles till I vomit on
them.
1. The roll controls reverse at the worst possible times on
extremely rare surprise occasions sending the craft spinning to its death.
example: banking out of a steep turn near the ground resulting in spin in death.
Downward deflection of an aileron (or any flap) can cause wingtip to
stall (it lowers the angle of attack for the stall by moving the lift curve of
the wing section to the left).
If the airleron is not allowed to go down but
only goes up, then this type of stall can be eliminated, a side effect is that
you cannot lift a down wing near the runway with just roll control, you have to
apply elevator control. Spoilers operate similarly but produce more drag and
loss of lift so should only be applied after the up only airleron is at maximum
travel to avoid los of lift during climbout turns as experienced with the
Mitsubishi M-2 spoiler controls.See Taifun.
Solutions known since the
1930's have not been implemented. (spoilers, inboard airlerons, slats and droop
noses and vortex generators,Split Tail feathers/Differential all moving tails)
Adverse Yaw of ailerons is the drag created by the lift of the up airleron
that rotates the aircraft in the opposite direction of the rotation that should
be associated with the turn. The only up airleron solution above, and spoilers
solve tis problem, resulting in better coordinated turns, and therefore reduced
stalls.
2. Burst into flames on
impact. Even new designs ignore costless fuel system design
guidelines from 1964. Here is how.
3. Flight is taught by
airspeed, but it the correct airspeed varies by 7 or 8 simultaneous
variables. Textbooks from the 1930's plead for some kind of AOA
indicator, almost nothing has been done.No functional Take off speed
indicator and Angle of Attack indicator is STC certified and standard
equipment on any General Aviation Aircraft. Not even the piece of
yarn on a stick that was the Wright Brothers sole instrument 100
years ago. There are virtually no angle of attack gauges installed in
General Aviation aircraft despite their manufacture and availability
under TSO.
Something called the Phugoid oscillation
http://www.av8n.com/how/htm/aoastab.html
causes the aircraft to
hunt around an airspeed when the main wing is held at a constant
angle of attack, The aircraft can theoretically fly at times below
the stalling airspeed because of energy exchange while the main wing
angle of attack remains the same. Pilots chasing to hold an exact
constant angle of attack by moving the elevator can exacerbate the
airspeed and altitude excursions change.. This occurs during low
speed landing approaches when it is most burdensome. This oscillation
complicates the otherwise simple angle of attack gauge as the primary
flight instrument, by creating the need for pilot or instrument
dampening. Still this problem could be overcome as most accidents
occur by getting far into the wrong angle of attack without any
feedback at all. Obsessively chasing feedback in great detail seems
the lesser of evils.
In the ideal aircraft there would be no
phugoid oscillation. It may be possible to use an all moving
zimmerman planform tail to increase dampening. More tail lever is
supposed to increase dampening but maybe not for the phugoid since it
is caused by the relative size and moment arm differences between the
main wing and the elevator? Certain solution is not clear to
me.
Someone said A true airspeed dependent fixed pitch
propellor has changing best climb speeds with altitude changes, so
the best climb speeds at high altitude would be a bit less than angle
of attack of lower altitude would indicate.
6. The AOPA says
in print(mountain flying handbook) that the POH handbook runway
lengths are dangerously stated as a sales tactic.
7. The POH
gives the climb in Feet per minute but not in feet per mile or per
thousand feet etc. or inverted. Which is what you need to calculate
object clearance.
8. A Decrease in density causes an increase
in Density .....Altitude. Too confusing, calcs don't get done
4.
No desk, or clip or place to hold the checklist or POH or maps or
anything, It as the same as if restaurants expected you to eat in
your lap without tables.
9. Books manuals and instructors
contradict each other, no one in charge or comprehensive reliable
authority.
11. Accident rate per flying hours is believed to
be poorly calculated , and has probably not improved significantly
since world war 2.
12. No place to go to the bathroom. No
place to hold drinking water.
13. Steer with your feet? it is
harder to taxi than to fly. Soap box derby steering?
14.
Spiral dive is not indicated by a yaw angle device? or maybe that
would help a little? As an aircraft enters a graveyard spiral dive,
there is not yet an aerodynamic design that prevents or fixes this
condition. Dihedral can actually fix the dive in some designs if the
pilot lets go of the controls, as it is his illusion that causes it
generally. Adding too much Dihedral can cause problematic Dutch Roll
and other misery. So how about a variable Dihedral, this could be
mechanical or aerodynamic or fluidic. As the down wing sideslips the
flow could cause extra lift on that wing, as the upwing could have
down force on it, of course this is what dihedral does, but as the
front of wings have high lift devices with only operate at certain
angles of flow, so the tips of a wing could have devices whose effect
is only felt or occurs at the extremes of flow, otherwise it is as if
it is not there. These could be lever operated wingtips, blown in
doors, and or static pipeing of side wind piped 90 degrees into
Coanda effect blown surfaces. There could be a shared functionality
with wingtip anti stall devices. The Bombardier Water Bomber wingtips
form all dihedral, for the wing is straight, and could be an avenue
to investigate.
15. Center of Gravity Calculations don't get
done, no effort to simplify the calculations by the manufacturers,
minimum information required by certification is in the Pilots
Operating Handbook
16. Anti Torque Rudder or "P"
Factor requirement can be designed out of aircraft.
17.An
Ideal aircraft would not have different elevator angle to main wing
angle of attack with changes in thrust or changes in flaps.
18.
Stick Force: the design of the aircraft requires enough elevator
authority at forward Centers of Gravity with flaps and power, Then at
aft centers of gravity and no flaps it takes little elevator
authority to stall.
19. Stick Angle: With power and flaps the
aircraft will stall at a more forward (or less back) position of the
control than it would stall in a flapless power off glide.
20.Installed "Indicated Airspeed" does not equal
Actual "Calibrated Airspeed". Especially at slow speeds
near the stall. This adds a non linear calculation step that varies
with aircraft and installation. This limits easy instrument marking
and ring calculators and in head calculations that could be standard
equipment across all aircraft. Test pilots use instruments that are
Actual airspeed, then they take them off and leave us with the lousy
ones.
21. Ambiguity and inadequate information and difficulty
of removing flaps and adding power while initiating a go around on
landing.. here's a classic recent accident:
The pilot of the
Piper said his sink rate was faster than he expected on the approach,
so he added power and retracted some flap. It was noted in the report
that retracting flap in that flight condition would increase the sink
rate. At any rate, as he did so an SUV occupied by a man and his
14-year-old daughter crossed from the left and the aircraft hit the
vehicle, killing its occupants. The pilot and his two passengers
survived, and the pilot later told investigators he thought he would
clear the vehicle, which was on a public road less than 18 feet from
the beginning of the runway. The NTSB says the FAA would normally
require at least 300 feet between a road and the end of a
runway.
23.Another Control Reversal Nightmare,,
Elevator/Canard stall and Tailplane Icing etc.
If your
tailplane or elevator stalls for some reason you have to pull the
stick backwards to get the nose down. The exact opposite of what you
normally do. This is actually part of the POH for aircraft like the
Q400 Colgan air crash. But maybe your main wing is already stalled
and you are out of luck, or maybe you don't know whether the tail is
stalled or not and you guess wrong and stall the main wing, or dive
to fast.
How could this unreasonable situation occur? In the
early days of aviation, some tail surfaces had low aspect ratios and
semi circular rears, which delays or eliminates stalls. In newer days
the emphasis is on cruise efficiency so high aspect ratio
tails are used to minimize
the necessary angle of attack tip vortex losses needed to trim the
aircraft against the forward center of gravity. Some aircraft even
move the fuel around to maintain minimum forward center of gravity.
Then if your tailplane get ice on it and or you get into some unusual
airplane attitude, you may not be able to get out of it since the
tailplane is past its stall angle.
Another way of avoiding
control surface stalls was seen on the tail fin of the WW1 triple
decker which had a pure circle tail fin which was all moving. An all
moving surface can assume large angles to the flow to maintain its
effectiveness, whereas the fixed tail with rear movable surface is
limited in the angles of its effectiveness. The movement of the
movable surface (flap) away from the center position lowers the angle
of attack at which it stalls which exacerbating the limitation of the
angles of effectivness of the tail relative the attitude of the
aircraft to the airflow.
Building all moving tails is more
difficult, hinging and trim and mass balancing and control forces
present challenges to the designer. The beneficial extra control
force available can be a detriment if misused at the wrong time by
the pilot so means do discourage this kind of mistake should be at
their utmost, see above for Angle of attack indicators and stall
limitations on wings etcetera.
24. Artificial Horizons Tumble
at extreme angles and become useless.Except the Russians have had an
artificial horizon that does not tumble all along! but we don't want
it because it is Russian!
It seems to be poorly publicized
information that the instrument that is supposed to keep you under
control in the clouds stops working at precisely the moment that you
need it most, at that moment you are supposed to realize this
occurring and switch to the turn and bank indicator and indirect cues
and rote recovery schemes. Good Luck! Variations in the angle and
propensity to tumble varies across models and has never been
disclosed to me. The simple rate gyro of the turn and bank indicator
apparently does not tumble. Apparently the Russians use an artificial
horizon display that spits the two axis of mechanical artificial
horizon display into two separate components, this display apparently
does not tumble. There is some evidence that it is also more
intuitive to first users. The horizontal is like a separate turn
indicator which tilts relative to the instrument NOT to relative to
the panel. So it is like you are flying the the airplane in a
separate world by remote control. The The Russians have rotten
weather and maybe know what they are doing. Our Type of Artificial
Horizons are apparently have become standard though horrible and
likely a cause of much death. I do not know if the new electronic
displays tumble or not, I do know they fail for lack of electricity
and other reasons. In particular engine failure is a threat to
aircraft systems. For myself I would like a wind driven venturi
artificial horizon of the non tumbling type. Here are some
photographs of Russian types. Some of the Russian types have inverted
coloring to our expectations.The model number of the newer on seems
to be AGB-3. I have not found a source although US YAK operators do
have them. Presumably India,China and Russia would be potential
sources. If they are not certified in the US for non experimentals,
They could be placed next to a certified unit of the other display
tumbling certified type.
25.
Instrument (Blind) landing systems antenna project a glide path for
the plane to land at on the runway... but … the antennas also
project a more incorrect beams above and below the correct beams
which will guide the plane to an unaturally steep or flat glide that
will probably confuse the pilots into not bieng able to maintain on
the beam and hopefully go around or in some cases crashing into the
ground. Autopilot
systems that attempt to help the pilot by extrapolating a from a lost
signal may guide the plane into the ground base on a brief exposure
to the wrong signal.