Kevin,
I answered this question not to long ago and for the life of me can't
find the really long and boring answer I gave to someone else. So I
made another one.
The AOA pitot from Dynon has a hole at 45 degrees or so to the normal
pitot hole. It also has a bleed hole on the bottom for the pitot. It
is a pressure differential indicator between the two forward holes. So
it works like the Europa stall indicator but with a pot to give
progressive indications rather than a single pole switch. It can be
purchased heated which is really nice. Watch the amps though.
Longer answer:
Dynon has specific instructions on mounting position which is from the
leading edge from 2-10 inches back and hanging from the Gretz mount.
The aileron access hole is too far aft. As the relative wind hits the
wing bottom it straightens out and the Dynon will not get a good enough
angle difference to work as well as it should. This parallel flow of
the air under the wing is what makes the Europa XS pitot so accurate but
will not allow the differential pressure of the angle of attack function
of the Dynon very accurate. I'm afraid I believe it best to make a hole
in the wing.
I install the mount by making a 5- 6 inch hole in the forward outer wing
panel. Make a flange of four layers of bid like an access panel flange
support. Make a thick mounting plate or reinforce the blank you cut out
and cut for the Gretz install. Make sure the tube is aligned properly.
Install the Gretz and screw it in. Run the new pitot tubes (use your
existing static as is) for the Dynon pitot and AOA inputs. Hook the
existing pitot from the Europa tube to your other airspeed indicator as
a backup. Just feed the new tubes through your wing tip light conduit
and rout them to the front of the spar at the tip to the Dynon pitot. I
installed it on a couple of aircraft. Not a great use for me as I don't
look at the Dynon on short final, but it works great in the pattern and
stall training for a low speed sensor type warning...
I prefer the long probe built into the wingtip sticking out two feet for
accuracy, (I built one for the LSA testing) but what a bugger to walk
around and fix when you bang into it. But it works really well until it
is time to take the wing off and store it. The the tube must come off.
The XS style pitot is very accurate and requires no calibration
normally. However, your electric EFIS may.
For others considering AOA advertised systems (read as long and boring):
I am opinionated on AOA so here goes. After flying century series swept
wing aircraft in the military, and then observing the AOA installed on
Navy propeller trainers and the US Airforce T-37B I have come to this
opinion.
An AOA is essential for the large range of angle of attack possible
(from zero lift to max lift at 19 degrees and maximum AOA of 30 degrees)
and the specific angles needed to fly a swept wing aircraft properly.
Most swept wing aircraft have little or no stall feel from max angle of
lift to stall and the drag increases dramatically above approach speed
and max lift angle. So if you get slow, these planes just sink faster
nose high. The lack of feel of the high angle condition lulls the
novice pilot into a slow speed approach at a steep angle of attack and
approach angle without a feel of being slow. So, to prevent the
horrible initial high sink rate low power approaches (remember the older
turbojets didn't spin up too fast) air brakes were used on approach to
keep the engine revs up and the AOA gave the pilot the indicator for his
aircraft approach angle of attack and coupled with proper glide path
control, and final approach airspeed calculations, all was well. In the
F-4, F-5, T-38 and F-106, we always computed the final approach airspeed
as well as flying the AOA. ( F-4E and T-38 were 155 Kts plus 2 knots
per 1000 of fuel and external payload if memory serves.) AOA
indications were our only alert if we were getting too slow from lack of
attention. However, that was not good enough, so a tone was added also
to bitch at us, sorry, alert us to the slow approach speed / higher than
standard AOA due to our inattention to airspeed control. For
maneuvering in combat the tone alerted the pilot to high drag and
airspeed bleed off due to excessive angle of attack (beyond max lift)
maneuvering. Hence the term on the tone or optimum turn was coined. At
the sound of the tone, the back seater in the F-4D would lock his knees
as aileron input from a new aggressive pilot caused a departure from
controlled flight above the tone, (followed by out of control bold face
actions and a deployed drag chute to recover if really done badly). The
plane flew quite well beyond the steady tone provided you rolled with
your feet. Hence we became skilled rudder pilots. The slatted E model
was much easier for the new guy and became the standard, but slower
solution.
In a straight wing aircraft, stall occurs with a fairly sharp break
about 14-17 degrees AOA. The T-34 (Beechcraft Debonair like trainer)
AOA system was for pilot training for the Navy pilots transitioning to
swept wing aircraft and to standardize operations. The approach in the
Europa no flap on a 2.5 degree glide slope is a comfortable 65 Knots
based on a 1370 lb, 49 knot stall speed. For short field approaches, I
fly 5 knots slower with full flaps. With full flaps, (Kevin, you have a
mono if I recall), your stall is 45 Knots so final should be 1.3 times
that or about 60. The angle of approach with full flaps plus deck angle
is about 13 degrees AOA. (Yea, I did a lot of calcs for the LSA mod on
this.) However at 60 your view of the runway and touchdown area sucks
if you are not head pinned to the canopy. So 65 works well. Remember
to add 5 knots for wind shear, turbulence and or gusty conditions (1/2
gust factor) but plan for a longer float. Please calibrate your
airspeed indicator if you haven't. Take the time, it is worth it. Then
calibrate your Dynon or other stall warning system. All this speed
addition adds to the float distance so get used to slow flight down the
runway.
The problem with the under wing style probe is that the up-wash effect
of the air approaching the wing and the slow speeds we fly make the
Dynon style pitot AOA/speed sensor less accurate than the holes in the
wing style (Advanced Flight System type) stall or lift reserve sensor
type of installation. The Right Angle is a vane type which is not much
use to us, but pretty good for the canard guys and the systems that use
the 4 pound chunk of aluminum out of the bottom of the wing are OK too.
All these systems require you to test fly and calibrate the system.
They use a pressure pot to give progressive indications as the speed
changes rather than a switch like the on-off system like the Europa
stall indicator (really more of a speed sensor). The Dynon is not a
true AOA but is a speed sensor difference indicator which works pretty
well. Again, as long as the systems are installed properly and
extensively calibrated, they all work and will alert you to a slow speed
condition.
My feeling is this. With proper construction and rig, there are good
aerodynamic cues for an impending stall. The Europa does not have hard
banging from turbulence as some aircraft, but has all the cues. The
cues can be enhanced by a simple angle on the leading edge of the wing
just a foot out from the root rib. Buy a 1/2 (3/8 is enough) inch
aluminum or plastic angle (1/16 inch thick), about 9-12 inches long, and
tape it to the leading edge root of each wing to get your appropriate
feel. For the mono place the point of the angle level with ground and
go test. If you get above that touchdown angle, the strip will start to
rumble. Then glass it up final when satisfied. Check the Ops manual as
there is more info there. This little strip will jar you into checking
your airspeed as the shake is pronounced on final or at altitude. Not
so much in the landing flare if you set it to trip the air at landing
attitude, but it is there. Aggressive slow speed maneuvering in a
straight wing aircraft will not allow any system to give you timely
stall indications as the lift curve slope is straight up to near the
break. The stab on the Europa, like the Century Series fighters, is
very powerful and you will rapidly overshoot the stall and will result
in a violent break or snap. Fly smoothly at low speeds.
Notes on landing:
Personally, I profess to fly 80 Kts. on downwind, no slower than 70 in
the final turn, 65 on final until across the fence and bleed to 60 on
short final in a flare over the overrun, winds and obstacles permitting.
At 60 there isn't much runway view so I don't get below 65 on final
until I am close to the ground and have good peripheral visual cues.
Maintain glide path until approaching the ground effect (about 6 feet)
and begin round out to the slow flight attitude or touchdown attitude a
few inches off the runway and allow the bird to settle tail wheel first.
Just keep it straight and fly down the runway until that slow flight or
landing attitude and it will reward you by touching tail wheel first
then squish on the main. Keep the stick back. Note the nose wanders
during power reduction in the flare as the Europa's center of mass is
quite tight and it yaws quickly with P factor and of course cross winds.
Warm those feet up and keep it straight. I use the wing low method in
crosswinds in the conventional but in the mono I use a crab and just as
I feel the plane settle, I try my best to kick out the tail to get
runway alignment as I caught an outrigger one time and it took every bit
of the 914 and Airmaster to get me off the runway when the outrigger
touched first and I was not quick enough on the rudder. I work to touch
the tail wheel first and jump on the rudder to maintain direction,
holding the stick aft until it bends the tube. On a wide runway I do
land on the downwind side and then straighten it up as the tendency is
to turn into the wind. The Advanced Flight System AOA type indicator
works very well on the mono, but the under wing style probes such as the
Dynon get confused by the air cushion under the mono and are less
accurate in the pre-touchdown attitude than they are in free air, but
you aren't going to look at it in the flare anyway on a crosswind.
Frankly, my max crosswind is 5 knots in a mono or conventional as my
proficiency is not enough to do initial flights with a crosswind in a
mono... It is not worth the risk until I get really proficient. (Read
as never.)
I use the same landing technique in the trigear. I touchdown at a very
nose high attitude (higher than the mono) and hold the nose off until
the nose wheel settles. Please do not round out high and mush it to
contact like Cherokee pilots land. Fly the plane to the ground effect
cushion and fly it as you were doing slow flight to the landing
attitude, as speed bleeds off the plane is only inches high and it will
settle to a slow speed well controlled touchdown... With the springs on
the nose gear, the nose gear can get bouncy if the touchdown occurs at
55 Knots and the stick is immediately relaxed (or just dumped as novice
pilots or us lazy old forgetful pilots do) and the new pilot will get
into a pilot induced oscillation, dribbling the nose wheel down the
runway. Simply hold the nose off until it wants to fall and relax the
back pressure. Don't yank on the stick to get the nose up at or above
50 because you will come off the runway at a very high nose attitude and
the results may be alarming. Normal touchdown speed is about 45-50 in
ground effect. On rough strips, hold the stick back always. High speed
nose wheel touchdowns will result in shimmy of the nose wheel
eventually. This is eliminated by setting the nose wheel breakout to
17-21 pounds and hold the nose off. 17 for grass operations or you will
never turn on wet grass. However on asphalt, 21 is recommended, as per
the manual, and make for smoother operations if you insist on high speed
touchdowns of the nose gear. (Readjust the dampener after 25 hours and
never over grease the nose gear pivot shaft via the grease fitting. ( I
hand lube it.) Grease on the shimmy dampener renders it useless. Make
sure the O ring is secure also as it prevents grease from getting on the
black plate.) As I said, I normally touch about 45-50 and hold the nose
up until it just won't stay up or I want to turn off. In crosswinds
exceeding 5 knots, you may decide to do less than a full flap or no flap
approach, so add 5 knots and after a wing low touchdown on one main,
when the other main touches, allow the trigear to weather vane a bit as
it is going to happen nose high or low anyway, but keep it on centerline
and lower the nose as you approach full rudder deflection or if you get
scared and have to grab the brake to keep it straight. Especially if
you didn't kill your drift...
For those with a fixed pitch props, or poor idle stop, you may find you
have residual thrust issues which prolong the float distance. Do not
get lulled into a lower approach speed as a moments inattention or a
wind shear or down draft will end up in a stall. Plan you approach
well. (Lower your IQ to a 2 and concentrate on aim point and airspeed.)
Try to avoid a steep approach, conditions permitting. Fly 65 with full
flaps stabilized on short final. The key is the stable approach. Once
clear of trees and fences adjust your aim point to short of your
touchdown point and pull your power a bit earlier slowing a bit to 60
after beginning the round out. Practice by doing low approaches to the
flare until you get the feel for what is necessary. Smacking the
aircraft into the ground is counter productive, fly the plane inches
above the runway until at the landing attitude and add power to hold,
then go around. Get the landing attitude picture in your head. The
work must be done in the approach and round out to the slow flight or
touchdown attitude until your proficiency makes it automatic. If you
don't know what the landing attitude is or need a refresher, go up at
altitude and slow flight a while at low power. The horizon to cowl
attitude or picture is worth a thousand words. That is your touchdown
attitude. (Mono guys just need to stare out the front just prior to
takeoff and memorize that picture for landing.) I preach not doing
touch and goes but to do very low approaches to gain proficiency in
handling close to the runway. It saves tires and wear and makes you a
more proficient pilot. If you are afraid of the ground, you can't land
well. Develop your skills and feel for where the runway is. Find the
instructor who says you just bring the plane in and chop power, pull
back and hold it until it stalls just as you touch down and shoot him,
as it is justifiable homicide. No control is possible in a stall. You
fly the plane to the runway and fly it until it is at the landing
attitude and allow it to settle in to a touchdown (since with no power
it will begin a slight sink or settling which will be very near the
stall). As proficiency increases, so does the amount of backpressure
you will need to maintain flight and you can, in ground effect, actually
drag the trigear tail before the Europa will stop flying. Not
recommended as paint and touchup will be required. Always account for
the wind and payload when approaching the field. Practicing at 1100
lbs. vs. 1370 lbs. is a big difference. If I recall my calculations, it
is about 2 knots per hundred pounds, so a light Europa may do fine at 60
Knots approach full flap, but be a short, hard landing at 1400 lbs. when
it runs out of lift early... which can be embarrassing and costly.
For the no kidding min run landing over an obstacle, a US Navy style AOA
on speed to touchdown may be required. This is a power on 60 Knot
approach slowing to 55 nose high until right before touchdown and
pulling the nose up (even adding power a bit) to the landing attitude
and an aggressive power reduction to touchdown, or, if misjudged,
impact. It works, is hard on the plane, requires nerves of steel and
repair skills if done repeatedly or poorly. Soft field landings
require no special skill, just a normal landing carrying a bit of power
at the end will slow the rate of sink, but so will a proper normal
landing with full flaps.
Regards to all. I have been flying a lot lately doing transition
training for clients so I'm dumping on you all what I have been harping
our new owners on. All of which are doing excellent landings in the
conventional (three point) and trigear.
Back to work. I haven't hit 70 hours of work this week so I must get to
it. Much paperwork for taxes.
Regards,
Bud Yerly
Europa Tech Support
Custom Flight Creations, Inc.
www.customflightcreations.com<http://www.customflightcreations.com/>
(813) 653-4989
----- Original Message -----
From: klinefelter.kevin@gmail.com<mailto:klinefelter.kevin@gmail.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Friday, April 13, 2012 12:08 PM
Subject: Re: Europa-List: Re: Pitot Static
Hi All,
I'm thinking about adding Angle of Attack function to my Dynon D10a
unit. This requires the Dynon aoa pitot to be installed on my completed
wing. I think that could be done easily by mounting the pitot on the
bellcrank access cover. Has anyone done this successfully?
thanks, Kevin
Mono 914, 400hrs
On Mar 31, 2012, at 1:09 PM,
jimpuglise@comcast.net<mailto:jimpuglise@comcast.net> wrote:
Paul-
I mounted my Dynon on the same wing as the Europa probe. It mounts
a little more toward the leading edge as I recall. I think I mounted
mine just behind the spar. If you have closed your wings, you would
need to put a hole in your skin to mount it, and do as Bud said and use
the Gretz mount. I backed my Gretz mount with 1/16 plywood and BID. I
put them in the same wing to avoid putting a run of irrigation tubing in
the other wing also. The four tubes share a length of tubing to the
wing root. I actually had to change the tubing and was able to get to
it through the inspection port and do it in only an hour or so. I used
a "T" connector to use the Europa static port for the Dynon also. Works
fine. I have photos of it all if you need them.
Jim Puglise
N283JL -- 15 hrs and fighting cooling devils
-------------------------------------------------------------------------
---
From: "Bud Yerly" <budyerly@msn.com<mailto:budyerly@msn.com>>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Thursday, March 29, 2012 9:39:28 PM
Subject: Re: Europa-List: Re: Pitot Static
Paul,
I always put the standard pitot / static on my aircraft. It hooks
to the normal A/S and Altimeter. The Dynon probe is added to the other
wing normally and feeds the Dynon pitot/aoa. I make a 5 inch access
hole and build in a flange then mount the probe and its Gretz mount to
the wing about 10 inches back from the leading edge as that is what
Dynon recommends I believe for its AOA function. Should icing be a
consideration, I mount a cockpit static valve to use the cockpit air
which is accurate to about 2 knots and 50 feet at all speeds and
altitudes to 10,000 ft.
Do not mount the Dynon where the standard pitot is.
Regards,
Bud
----- Original Message -----
From: Europaul383<mailto:europaul383@hotmail.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Wednesday, March 28, 2012 2:47 PM
Subject: Europa-List: Re: Pitot Static
<europaul383@hotmail.com<mailto:europaul383@hotmail.com>>
Hi Bud (or anyone else who has an answer),
I read your post while looking for info on the Dynon AoA. I was
thinking of installing this AoA, but their probe has just 2 holes -
pitot and AoA - I'd then have to find another source for the static air
- can you recall what George Reed did for static?
Thanks in advance.
Paul
XS Mono 383
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