Maneuver Techniques and
Judging PointersRudder Control
(Sportsman and Intermediate)
When you first start flying pattern you don’t even think about it. Once
you’ve had a little time in the sport, you start to notice some people never seem to
need to correct their line while others are constantly banking to reestablish their
heading. Well, those that are banking the model with aileron are noticed by the judges,
the other flyers, the spectators, the concession attendant, the horse standing out in the
field and anyone else 
who may be watching. That’s not the way to
correct your heading. Rest assured the pilot that always seems to be on heading
didn’t get there by just having a well trimmed plane and being lucky in his
maneuvers. I once commented to Glen Watson that he never seemed to make corrections. His
response was "I never quit making corrections." He was just doing it in a way
that was less obvious and almost stealth. Glenn won 7 of 8 Intermediate contest he
entered.
OK then, how do I go about making these less noticeable corrections to my heading. It’s that other control that you only use for takeoff and stall turns, the RUDDER. I competed a season without using the rudder to any real extent and placed in the middle of the pack in most contest. Once I started using it reasonably, I started to score much better. This is a necessary control if you want to compete effectively in Sportsman and Intermediate and essential in higher class if you want to keep your shinny pattern plane in one piece. The point is, learn this control when you start and you’ll be far ahead of your competition.
To learn to use rudder, you must have a starting point. The plane does manage to get into some reasonably strange positions sometimes and knowing what rudder to push isn’t always intuitive. Well, it’s almost never intuitive to a new pattern pilot. I’m going to give you a way to think about rudder. It’s not the only way and maybe not the best way, but you have to start somewhere.
Ideally, you want your model to have a pure response to rudder (when you push the rudder, the plane only yaws and does not roll). If you have a computer radio, the mixing functions will take care of this, otherwise you may (will) have to use some aileron to get the necessary response (harder!). Your position in the pilots box is also important. I strongly recommend you stand with your shoulders square to the flight line with the radio’s antennae pointed down the centerline. Assume this position and don’t move for the entire flight. If you move your shoulders during the flight you stand the chance of losing reference to the correct line. This position also gives you the best chance to develop a mental picture of the required corrections.
These suggestions may seem a little mechanical, and they are, but with practice they become easy. Rules:
- Rolling from upright to inverted, the sticks go in opposite direction. Right roll, left rudder; left roll, right rudder. This will always give you top rudder when you are knife edge.
- Rolling from inverted to upright, the sticks go in the same direction. Right roll, right rudder; left roll, left rudder.
- When the line needs to be corrected and the plane is upright, I find it easy to visualize myself in the cockpit and push the nose of the plane in the direction it needs to go. Standing square to the flight line makes this easy. If the plane needs to move the nose right, push right rudder.
- If the model is inverted and the line needs correcting, I again go mechanical (can’t seem to get myself in an inverted cockpit without going goofy). If you’re coming in toward center, inverted, push the nose in the direction it need to go. If the nose needs to move right, push right rudder. Use your eyes as the direction for the rudder. Your head is turned to the plane so push the rudder toward the eye that would put the nose where you want it. Think about it! Once past center, going away, push the tail in the direction it needs to move. If the tail needs to move left, push left rudder. Push it toward the required eye.
That’s it for the mechanical part. Pretty easy huh? Now let’s put these rules to use and talk about practicing.
- Correcting your line while upright; straight flight out, straight flight back, setting up for and exiting maneuvers, etc. Do a complete flight of just flying a straight line along the path you will use for your maneuvers. Use the rudder coming in and going out while visualizing yourself in the cockpit and note the aircraft movement. About a tank of fuel and you should have this down.
- Half Reverse Cuban Eight: You’re always looking at the tail of the airplane when you start this maneuver. As you pull up into the 45 degree climb note the position of the nose as if you are sitting in the plane and make any needed correction. Release the correction and roll inverted, note the tail position and go mechanical. Since you are going away from yourself inverted, push the tail in the direction it needs to move. Do this a couple of times and the correction becomes automatic. This is already getting easier.
- Loops: Starting loops can be visualized just like starting a take-off. When I start a pull up for any looping maneuver I push the nose in the direction it needs to go. As the plane comes inverted, I assume I’m looking at an inverted airplane coming toward me and push the nose the direction it needs to go. Use your eyes as suggested above.
- For Intermediate flyers rolling inverted and upright, try making the rolls a little slower and using the rudder going in and out of inverted. Do this for your straight inverted flight and reverse outside loop. Use the mechanical inputs suggested above for these rolls (don't use rudder for the 3 rolls).
Start all corrections very gently as soon as you notice the need and gently release as quickly as possible. Experience and practice will make a big difference. Burn the fuel and it will pay dividends!
Don Ramsey
Here's another easy method (with practice) to always have top rudder in knife-edge. When you are looking at the bottom of the model push the stick toward the nose; when looking at the top of the plane push the stick toward the tail.
The discussions on this page came from the web site nscra-list@eskimo.com
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Four of the Sportsman (soon to be Intermediate) center maneuvers can be readily adapted to rudder drills. The objective is to fly them one after another without leaving the maneuver and to be able to move the whole maneuver in and out a prescribed amount. If you have a caller, have her call the direction and the amount of the correction. The easiest is the three loops. Remember to keep your wings level and make the changes with the rudder. Don't forget to pay attention to centering too!
The other three maneuvers useful for this drill are the cuban eight, the reverse outside and the square loop. Get real comfortable with the reverse outside before you use it in a rudder drill. A lot of good airplanes are lost on this maneuver, including one of mine!
It is tough to see the effects of rudder in the turnaround maneuvers, that is why the emphasis is on the center maneuvers.
In actual contest flying a measure of aileron is used to maintain track in both pushes & pulls. This seems to be a popular downgrade to the unschooled judge who takes points for "wings not being level". The only reference for downgrading "wings not level" that I have found is in the avalanche and I think there could be better wording on that. Sometimes getting it right is not enough, you have to be able to fly what the judges want!
John Ferrell
Horizontal
rudder exercise: We’ll apply this to learn how to use your
rudder. If you have a reasonablly well trimmed pattern plane it should be able to do flat
rudder turns without dropping or raising the nose or without much roll coupling. Just
start by flying level at a safe height and perform flat, big horizontal eight's in front
of you using rudder only, but relax the sticks to neutral in the crossovers so you will
need to think before inputs for the next half of the eight. Enter the eight's from all
directions and fly left to right and right to left. Then when you’re good and don't
make mistakes upright, do it all again inverted. Do this high in case you get confused.
Vertical Rudder exercise: The best way I found to practise vertical rudder control was to do a particular stall maneuver. Figure M with 3/4 rolls in the up and downward leg rolling in the same direction. Each pass gives you the chance to do a left or right stall turn with the plane facing you and one facing away from you( easy). Also there is a lot of chance for correction with rudder in the up and down legs of the M.( This maneuver is harder to perfect than it seems at first). The rolls in between help to confuse a bit and put you off tract especially in cross wind but skill at rudder control will keep you online even in the wind. In this figure M you have to do the stall turn under a bit of pressure and the rudder inputs soon become instinctive. This maneuver is not recommended for the raw beginner as it has a reasonable K factor and there is a bit of inverted pushout at the bottom of the middle on the M. Practise it from left to right and visa versa.
These two maneuvers are all that is need to get you use to rudder control. I have found the controls I use the most are the throttle and the rudder. I don't know what the others think but the rudder probably gets used the most.
Hanns Lim
So far you have received
alot great advice. Here is 2 more cents to throw on the heap. I like to think of my self
as a pilot that learns by engraining from practice/redundancy. If I have a particular
maneuver or discipline (rudder) I feel needs improvement, I like to step away from
practicing the whole pattern routine and burn several tanks doing just that one thing.
Then go back and apply lessons learned to flying either that section of the pattern or the
entire routine.
Glen Watson (Editor note: 1998 National Champion Advanced)
I did do an article on
that -- but it may have been in the sport mag I wrote for. The drill was mentioned here.
It is really a deceptively simple one - practice sliding the model - whilst holding the
wings level -- first - from end to end of the box - then reverse etc.- The results take
time and many sessions, for the mind to lock in -and -if you rely on "remember to
push to the Error side" method for selecting correct rudder -- you will surely err--
reason being that rudder must become as ingrained a response as elevator input -- IF you
really want to get proficient-you must learn to fly REGARDLESS the state of trim or
inherent couple in a model. An old friend once told me (and this guy really was good)
"just fly it" when I asked him how to trim for various maneuvers. He could fly
any mode and used no HI/Lo rates etc-- Tho this kind of skill is rare , The idea has merit
- for example - I still get questions concerning "how much right thrust is
correct". Once you get comfortable with constant rudder flying , you will find that
NO offset works very well-and , in fact you will not even notice it. Another drill that
helps is learning to fly using a tray - if only to find how much "English " you
put on the TX as you fly- A strap is very helpful - and is my own favorite - but I have
seen too many different approaches to holding/thumbing etc to say one method is superior-
Bottom line - A well practiced flyer will usually beat a flier who relies on special
models, trimming .etc--because he simply learns to deal with ANY situation.
Dick Hanson
When upright, the FAR
side of the plane goes the direction you push the rudder stick. e.g., going away the nose
(far side) goes to your right when stick goes to your right. Coming at you the tail
(again, the FAR side) goes to your right when stick goes to your right.
Inverted, going away from you the TAIL (near side) will go right when stick goes to your right. Inverted coming at yourself, the NOSE (again, the NEAR side) will go right when stick goes to your right.
So - When upright, steer the far side with the rudder. Inverted, steer the near side. (Also works on vertical lines.)
This short, simple "mantra" has kept my heli out of the dirt many, many times while working on nose-in landings and inverted hovering.
d'hawk
The key criteria in
the Double immelman w/ full rolls is that the rolls start immediately after the half
loops, and that the roll rates be equal. Unequal distance covered relative to the ground
due to differing upwind and downwind wind vectors is not considered a downgradable item.
The length of the straight horizontal legs should be equal to the diameter of the half
loops -- giving a centered "square" within the maneuver.
ALL of the Double Immelmanns are the same, except in Texas, where the length of the maneuver can be double to triple the height to allow for super slow rolls over all that open space. LOL!
Speaking as one who has written (and edited) his share of rules, if every rule we have in the book was clarified sufficiently so that there could be no possible misinterpretation, the RC Aerobatics section alone would out-weigh the NYC telephone directory -- and there would be endless calls for the the Contest Board to "simplify" the thing so normal (non-lawyer) people could read it.
Seriously:
Rick Allison
Glad to see your
response...accurate in my experience. The risks of too slow a roll rate FAR outweigh the
perceived advantages. A good judge, who is being accurately critical of LINES and LENGTHS
before and after such rolls will hesitate on that HIGH score unless it is a definite
line....that ooozzy, beautiful slow roll, while it may be PERFECTLY executed, COULD be
ruining the line definition, which is a significant downgrade criteria. The other point
John makes about roll rate is also true - they NEED TO BE THE SAME....HOWEVER, keep in
mind that the same RATE roll uses different amounts of the line, depending on airspeed.
Our challenging job is do BOTH. Regardless of wind. My method, FWIW, decide on a fixed
rate, count it to memorize it, then fly it consistently. Makes the Double Imm and other
things easier... Bob Pastorello
With any wind
blowing it would be impossible for the rolls to end in the same relative position. This is
because with the rolls having the same angular rate of rotation, ie. both rolls would take
the same amount of time to complete, the distance relative to the ground (our
persepective) traveled during that time will vary based on the aircraft's ground speed and
this is not a downgradable item. Dave von Linsowe
There are a couple
of interesting points raised in discussing the double I w/full rolls. The easiest
downgrades relate to the centering of the maneuver. The rules say the middle of the double
I must be a centered square. Any wind corrections you make to accomplish that do not
change this criteria. You need to go into the wind far enough so that you can do a 1/2
loop that ends in the same place as where you started you then do a full roll. On the
downwind side you have to start and end the 1/2 loop in the same place. This is where you
were seeing problems. In order to have sufficient speed coming back into the wind to do a
full roll the tendency is to make the 1/2 loop to tight. The result is no square and a
severe downgrade.
The maneuver also requires the full rolls to be at the same rate. A full roll downwind at a given rate and upwind at a given rate take up a different amount of space on the line. The total line length doesn't change. Herb Kurlan
Wow I hope it wasn't my answer that got this confused. The line segments including the roll must be of equal distance. The height of the maneuver must be approximately equal to the length of the line segments so that a square is formed in the center. The maneuver must be centered. As in all Immelmans the roll must start immediately after the 1/2 loop. The amount of space taken up on the line segment by the roll is not a judging criteria. The roll rates must be equal so in a strong wind it will look like one roll is shorter than the other on the line segment. You are not trying to make the rolls end equal distance from center. Hope this clears it up a little bit. Herb Kurlan
The Immelmann
family is the ONLY exception to the "roll must be centered on line" rule. NONE
of the Immelmanns allow this; in all cases the rolls start imediately after the half loops
and must have constant roll rate. The double immelmanns (DI) are flown with the MANEUVER
centered, so the roll COULD be centered if the roll rate took the full width of the
maneuver to complete. The shape of the DI with full rolls is described, must be a centered
square with half loops on the sides. DI w/half rolls only requires that min. 1 sec level
flight after half roll, so it's normally more oblong and the rolls can NOT be centered.
Even the Novice
class Immelmann has a roll that is not centered, either in the line or actually centered,
since it (the half roll) STARTS at center. Eric Hawkinson
Spins (Everything you ever wanted to know and then some)
Here is an email from Stephen Mitchell an aeronautical engineer friend about spins. He has read the emails and gives his learned opinion.
SUMMARY ABOUT SPINS: STEPHEN WROTE.Let me try to explain what is happening with the ailerons in a spin ....
First there are some fundamental things about spins that you need to understand.
A spin can never happen unless the wing of the aircraft is stalled asymmetrically. Just because the wing has stalled does not mean that the complete wing is stalled. In virtually all cases part of the wing will be stalled whilst the remainder is unstalled but flying at high AOA. The assymmetry results from one wing having a greater extent of the wing stalled than the other side. The plan form of the wing (ie rectangular or tapered), airfoil and wing twist etc will influence which parts of the wing stall and which parts remain unstalled.
When an airfoil stalls it continues to produce lift but less than just before the stall. In the stall the air is separated from the upper surface but typically remains attached to the lower surface. This means that the ailerons will continue to effect the pressure distibution around the stalled wing and thus continue to have power (allbeit reduced) to roll the aircraft.
When the aircraft is spinning it is both yawing and rolling ..... think about it. Basically the motion is a supperposition of these two motions. Now we can consider each of these motions separately. Increasing the speed of either the rolling motion or the yawing motion will increase the rate of the spin (with a corresponding change in the attitude of the aircraft in the spin).
The yaw rate can be increased by a number of means: 1. Reduce the mass moment of the aircraft in the yawing direction. 2. Reduce the side area of the fuselage. 3. Reduce the size of the rudder. 4. Apply rudder.
The roll rate can be increased by the following means: 1. Reduce the mass moment of inertia about the longitudinal (rolling) axis. 2. Increase the size of the ailerons. 3. Apply ailerons. 4. Reduce the span (which reduces the aerodynamic damping resulting from the asymmetric lift distribution that developes when the plane rolls).
If you think now about the motion of the coupled yaw/roll that we call a spin if we apply ailerons into the spin (ie stick towards the centre of the spin) then the rate of roll will be increased and the spin rate will increase. The spin will also become more upright (ie nose down).
The converse is true with out of spin aileron (ie reduced spin rate and a flatter spin).
QED Steve.
Point 2.
Spins have three phases, incipient, fully developed, and recovery. The following are excerpts from the Cessna Manual of Flight: The spin is the most complex of all flight maneuvers. There are actually hundreds of factors that contribute to the spinning of an airplane. In a light, training airplane a spin may be defined as an aggravated stall which results in autoration. During the spin, the airplane descends in a helical, or corkscrew, path while the angle of attack is greater than the critical angle of attack. PRIMARY CAUSES a stall must occur before a spin can develop. However, a stall is an essentially a coordinated maneuver where both wings are equally or almost equally stalled. In contrast, a spin is an uncoordinated maneuver with the wings unequally stalled. In this case, the wing that is more completely stalled will often drop before the other, and the nose of the aircraft will yaw in the direction of the low wing. Typically, the cause of an inadvertent spin is exceeding the critical angle of attack while performing an uncoordinated maneuver. The lack of coordination is normally caused by either too much or not enough rudder control for the amount of aileron being used. The result is a cross-controlled condition. If you do not initiate the stall recovery promptly, the airplane is more likely to enter a full stall that may develop into a spin. The spin that occurs from cross controlling usually results in rotation in the direction of the rudder being applied, regardless of which wing is raised. In a skidding turn, where both aileron and rudder are applied in the same direction, rotation will be in that direction. However, in a slipping turn, where opposite aileron is held against the rudder, the resultant spin will usually occur in the direction opposite the aileron that is being applied.
Point 3
My point is...if a pattern plane will spin with "in-direction" aileron, it
should also spin without it, assuming there is enough elevator authority dialed in.
Yes it will spin but at a slower rate......therefore may not look as pleasing to the
judges.
This is an important point about the elevator .. the amount of up elevator available has a significant influence on the spinability.
I have only come a cross a few pattern planes that will do a rudder-elevator only spin. Our current plane designs are too "stable" to remain stalled thoughout the spin using elevator and rudder only.(tend to become unstalled and fly out of the spin as speed increases...or?? not stalled in the first place on entry.). This is because of the problem I mentioned yesterday ... the long rear fuse tends to stabilize and stop the autorotation. That is why your pattern planes don't spin well.
The rudder and elevator power may not be great enough in our usual setups. Yes
The aileron makes the spin look more tighter/narrower and visually reduces any chance of the axis of rotation looking like it will circumscribing a circular path--zero (insipient spin) instead of a vertical line downward. True ....
Point4
I always start the spin rotation with aileron and after 1 turn I remove the aileron and just keep rudder/elevator as the primary inputs. My spin entry is initiated by leading with rudder and then adding elevator/aileron. Keeping aileron in makes the spin accelerate too much. Yes this makes a lot of sence as it is during the initial transient phase of the spin that you need to accelerate the mass of the aircraft.
Point5
Late last year (before winter) I experimented entering a spin by coupling the elevator with upward going ailerons (I call this reflexing the ailerons). Consequently I made two observations, (1) the nose of the aircraft pitched upwards with less elevator than if the ailerons were not reflexed (should add that use of the throttle allowed the perceived altitude of the plane to be maintained even though the nose was pointing upwards) I would expect this in most situations .... (2) because the airplane had a relatively high angle of attack, speed for entering the spin could be controlled better, i.e. center was not over shot before the plane had sufficiently slowed down to it's stall speed. Yes the elevator had more power due to the reduction in wing pitching moment.
Hanns Limm
Next thing is the inverted spin issue...Are you spinning with lots of aileron? When inverted most planes need very little if any aileron...perhaps some to help start the spin but then come out of all but maybe less than 10% of the stick. This will work on the elevator also....As the plane stalls you need all the elevator it has to make the stall and start the spin. Then as its stalled and spinning you can come out of some of the that elevator. This will still keep the plane stalled and help you hit the rotations properly.....inverted spins are a little more tricky than upright ones.
Its all a timing issue on snaps and spins. You can't just slam the sticks into a corner and then let them go and expect the plane to snap and exit properly.
A buddy and I were talking the other day. He noticed that I was hitting my snaps pretty well and also noticed that he never heard my sticks snap back to center with the spring loaded sticks. We then thought about that function....and he came up with the evolution that an Advanced flyer they always spring back to center...In Masters sometimes they do and sometimes they don't its a transition depending on what snap is being done....And then comes the FAI guy and you almost never hear his sticks doing the twaaaang back to center on their own power.
Its a learning curve and it can be a very rewarding lesson to learn. Its the difference between making a controlled snap that is still very violent and stalled and has a controlled exit, and a bang the sticks and hope for the best response from the plane.
Troy Newman
This has certainly
been a good discussion. I suppose that the only way not to have judges with differing
opinions is to not have spins in the pattern. One thing that hasn't been mentioned that
might be useful. When training judges, I demonstrate to them what elements flown
improperly look like. First grossly, then more softly. For spins the gross errors
demonstrated are a snap into, a spiral dive, a down elevator "stall" with
vertical barrel roll, and improper number of turns. The softer error demonstrations
involve an "impatient entry" where aileron is applied early in the stall and
flips the wing over the top, an entry where the stall occurs but the aircraft unstalls due
to late rudder input then spirals for some rotation before breaking into a spin initiated
by the retreating wing again stalling, early spin termination with roll to heading. And
finally a demonstration of how the spin appearance may vary with different amounts of
control inputs, both with and without aileron, and yet meet the definition of a spin. I
disagree with the participants who've argued that certain control inputs negate any
possibility of a spin being a spin. If it looks like a duck -- you know the rest. Would
the same folks zero a roll that demonstrated improper aileron differential or mistimed
rudder application? The role of the judge is to provide a critical review of the way the
aircraft performs a maneuver basis the rule book description, deducting points for
transgressions. The dynamic nature of pattern ensures will always be some differences in
judgment and interpretation, however, participation in these type discussions and formal
judging forums go a long way toward agreement. Thanks for the participation.
Earl Haury
To add a bit to
this thread, IMHO. Forgive me for the rambling in advance - several items/comments in this
thread have sparked my interest - R. Ames wrote: > Coming out of the spin a half turn
or so early and doing a "wobbly roll" to > finish > it off sure makes for
a precise exit and is hard to discern; so does doing > a > "wobbly roll"
the whole way down. Are we going to ask judges to learn to > distinguish between spins
and "wobbly rolls?" Same applies for snaps.... Agreed. It can often be hard to
discern between a true spin and a wobbly roll. However, there are primarily two things to
look for to see if the exit of the spin is being "cheated" 1. IF the plane is
flown out of the spin to make the exit easier, it will transition from a stalled
conditioned to a non-stalled condition - which means the angle of attack will become
reduced - the change in pitch is a giveaway that the plane is no longer stalled and no
longer spinning. The applicable downgrade would be 1 point per 15 degrees of rotation that
the plane was not stalled. A half roll exit from the spin would equate to a 12 point
downgrade (and IMHO, I see this fairly often). 2. If the plane is flown out of the spin,
the rotation rate generally changes - it usually slows down a little bit and is then
constant again until the rotation is stopped. Planes that are borderline on the CG
location and have borderline amounts of elev and rud throw will often oscillate between
stalled/non stalled conditions during the "spin" - often easy to spot as the
rotation rate changes. Items 1 and 2 are useless criteria in the instance that the plane
was never stalled and never actually entered a true spin (and IMHO, I see this fairly
often). FWIW - as a judge and a pilot, I am very strict on spins (and snaps). The three
most recent pattern planes I have flown in competition were a Prophecy, an Ariel, and an
Elan. All three would stall with the application of elevator only. All three would spin
upright and inverted with elev/rud only. All three maintained a constant rate of rotation
during the spin. All three used 45 degrees of rudder throw. The Ariel and Prophecy needed
(IMHO) a full 30 degrees of elevator throw to consistently stall on entry and stay in a
true spin. The Elan used 35 degrees of elev. IMHO, the Prophecy was the hardest to
consistently get into a nice spin entry - and not coincidentally, it also has the longest
tail moment - which gives the plane extremely good lock in pitch (no surprise, just a
design compromise). I believe that any conventional configuration plane (I haven't flown
all of them) will stall and enter a true spin with the application of elevator and then
rudder - given enough control throw, and a CG that is far enough aft. The well designed
and setup planes will do this without overly compromising pitch and yaw stability in
normal flight regimes. The application of aileron during a stall entry, a stall, or a spin
may or may not have an effect on the plane - depends on many of the design aspects and
setup of the plane. It is certainly possible to force a plane into a true spin with the
use of aileron, and, I have seen some planes that transition from a true spin to a tight
spiralling roll when aileron is introduced. A hypothetical situation to think about
(because I would never advocate standing underneath a spinning plane) - If a
"spin" were viewed from directly underneath or above the plane, would it be easy
to tell if the plane were in a true spin?? I think so. If the rotation of the plane is
about the spinner (or roll axis), then the plane is not stalled, it is rolling about the
roll axis. If the rotation of the plane is about the yaw axis (should be very close to the
CG), then the plane is in a true spin. Regards, Dave Lockhart
An input of aileron
in the direction of the rotation will change the spin to a vertical roll. Bill, I am sure
you are well intentioned but the above statement is just WRONG. Control position is NOT a
criteria for judging - maneuver performance is. I have never seen an airplane that can
recover from a spin by adding aileron INTO the spin. You won't find it recommended in any
full-size aircraft manual that I've seen. It may be possible to overpower a spin with
ailerons but I've never owned a pattern plane where this is the case. At any rate it is
100% wrong to state that "any input of aileron will turn a spin into a vertical
roll." Control position is NOT a criteria for judging - maneuver performance is. My
Oly spun best with about 20% aileron into the spin at onset, then completely released. My
Desafio will UNSTALL if the ailerons are released entirely, but does beautiful spins with
about 30% aileron (in the direction of the spin) held throughout. Now, in either case I'm
sure that I could increase the elevator thro to spin without any aileron input, but I
don't use switches or rates and see no need to since the added drag from the ailerons does
the trick just fine. Just FYI, the Desafio will not go into a flat spin upright, no matter
how slowly I cross the ailerons nor what I do with elevator/throttle. (It just stops
spinning and falls into a spiral dive). The Oly, OTOH, did great flat spins as long as I
crossed the ailerons very slowly and left full up-elevator in. If using ailerons helps
initiate or maintain a spin then USE it. Control position is NOT a criteria for judging -
maneuver performance is. Likewise, if whatever you are doing allows the plane to unstall
during the maneuver, quit doing it! d'hawk
Judging Spins
One point of contention is that of zeroing the maneuver if a wing comes up rather than the fuselage dropping away from the horizontal plane.
As a judge, I admit to being a little generous here. If I am not certain, I cannot take a point for that fault. If the judge beside me calls it a zero because of the entry, we are only guilty of "best effort".
Personally, I think a zero for an entry flaw is too harsh for any maneuver. If it cannot be judged constantly the maneuver is too subjective to be scored at all!
I think a point of
contention is whether the track should be maintained entering and exiting the spin. An
example would be holding a 15 degree entry angle and exits on a parallel heading to flight
line. Did he do 360 degrees of rotation? Should he have entered straight or should he have
exited at the same angle to the flight line? I think that the stall is very hard to tell
unless you have a lot of experience watching that plane, whether or not someone forced it
in. Though I think it is very easy to tell if it is not spinning or comes out of the spin.
This is my two cents worth. :) Nemesis
I think these items need to be addressed: 1. Nose High -- I've heard several folks say that they can't make their plane stall decently without climbing. What is the downgrade criteria if it does climb? Gene Maurice made another excellent point in his post. See #3 below.
2. Wind correction during the spin. NemesisRC@aol.com (what's your name, friend??) raised this point in his post this morning. I want to see something put in writing so that everyone had the same understanding.
2A. What is the correct judging if it is necessary to hold a large crab angle for wind correction while approaching the stall? Do we stall at the crabbed angle, or rotate the plane back to parallel with the flight line just before the stall?
2B. Based on the answer to 2A, what are the downgrades? Do you start counting the number of turns from the the crabbed angle, or do you start from parallel to the flight path?
I think counting from the flight path is correct since the number of turns should represent the number of rotations _*relative to the flight path*_. My personal judging criteria has always been that a correct spin is one that _*Maintains Wind Correction*_ throughout the entry and exit, regardless of the crab angle. It impossible to maintain wind correction during the actual spin, since by definition the plane must be stalled. Wind correction on the down line after the spin is done with rudder (just like a stall turn), then a crab angle established on the horizontal exit leg to maintain wind correction.
I would propose the following:
Number of turns is relative to the flight path. Crabbing during the spin entry for wind correction is not a downgrade. Rotation must stop with wings perpendicular to the flight path after the required number of rotations relative to the flight path. Over or under rotation - 1 point per 15 degrees.
3. What actually constitutes a stall? Gene Maurice made a good point in his post - planes stall differently, and most judges do not have experience with every type of plane. I was told by one contestant judge that he wants to see the plane "quiver" before the stall. Sorry, but my middle-aged eyes don't see that well any more, especially at 150 meters. Clarification is also needed concerning whether forward ground speed during the stall constitutes lack of a proper stall. Anybody out there ever done a stall in a full-size airplane? Stall speed is NOT zero airspeed. In a Cessna 150 for example, it's about 50 knots. Unless there is a corresponding headwind of equal velocity, there WILL be forward motion of the plane relative to the ground during the stall. 4. Snap Entry: I like Mike Dunphy's definition. It's easy to remember and apply: "If the wing passes through vertical before the fuselage passes through horizontal, it's a Snap Entry -- zero. Write it down.
5. Push over entries: I've seem many folks (including several big "names") do this at the Nats and Team Selection, among other places. Seems they are concentrating so hard on centering that they blip in down elevator to simulate the stall break exactly on center. They fly a straight down line for a short distance, then commence the spin. Sorry, but that is a zero in my eyes, because if the plane is flying a straight down line, it can't possibly be stalled. The only way to get it to spin from this attitude is to SNAP it in.
That's all I can think of for now, Bob. -- Exiting the Box! Jim Johns,
To add a bit to
this thread, IMHO. Forgive me for the rambling in advance - several items/comments in this
thread have sparked my interest - R. Ames wrote: > Coming out of the spin a half turn
or so early and doing a "wobbly roll" to > finish > it off sure makes for
a precise exit and is hard to discern; so does doing > a > "wobbly roll"
the whole way down. Are we going to ask judges to learn to > distinguish between spins
and "wobbly rolls?" Same applies for snaps.... Agreed. It can often be hard to
discern between a true spin and a wobbly roll. However, there are primarily two things to
look for to see if the exit of the spin is being "cheated" 1. IF the plane is
flown out of the spin to make the exit easier, it will transition from a stalled
conditioned to a non-stalled condition - which means the angle of attack will become
reduced - the change in pitch is a giveaway that the plane is no longer stalled and no
longer spinning. The applicable downgrade would be 1 point per 15 degrees of rotation that
the plane was not stalled. A half roll exit from the spin would equate to a 12 point
downgrade (and IMHO, I see this fairly often). 2. If the plane is flown out of the spin,
the rotation rate generally changes - it usually slows down a little bit and is then
constant again until the rotation is stopped. Planes that are borderline on the CG
location and have borderline amounts of elev and rud throw will often oscillate between
stalled/non stalled conditions during the "spin" - often easy to spot as the
rotation rate changes. Items 1 and 2 are useless criteria in the instance that the plane
was never stalled and never actually entered a true spin (and IMHO, I see this fairly
often). FWIW - as a judge and a pilot, I am very strict on spins (and snaps). The three
most recent pattern planes I have flown in competition were a Prophecy, an Ariel, and an
Elan. All three would stall with the application of elevator only. All three would spin
upright and inverted with elev/rud only. All three maintained a constant rate of rotation
during the spin. All three used 45 degrees of rudder throw. The Ariel and Prophecy needed
(IMHO) a full 30 degrees of elevator throw to consistently stall on entry and stay in a
true spin. The Elan used 35 degrees of elev. IMHO, the Prophecy was the hardest to
consistently get into a nice spin entry - and not coincidentally, it also has the longest
tail moment - which gives the plane extremely good lock in pitch (no surprise, just a
design compromise). I believe that any conventional configuration plane (I haven't flown
all of them) will stall and enter a true spin with the application of elevator and then
rudder - given enough control throw, and a CG that is far enough aft. The well designed
and setup planes will do this without overly compromising pitch and yaw stability in
normal flight regimes. The application of aileron during a stall entry, a stall, or a spin
may or may not have an effect on the plane - depends on many of the design aspects and
setup of the plane. It is certainly possible to force a plane into a true spin with the
use of aileron, and, I have seen some planes that transition from a true spin to a tight
spiralling roll when aileron is introduced. A hypothetical situation to think about
(because I would never advocate standing underneath a spinning plane) - If a
"spin" were viewed from directly underneath or above the plane, would it be easy
to tell if the plane were in a true spin?? I think so. If the rotation of the plane is
about the spinner (or roll axis), then the plane is not stalled, it is rolling about the
roll axis. If the rotation of the plane is about the yaw axis (should be very close to the
CG), then the plane is in a true spin. Regards, Dave Lockhart
I would certainly
buy the "rotations relative to flight path" concept. As I mentionned before, I
have always been asked to "straighten up" before the break, which looks stupid,
but it's what judges wanted. As for the defintion of a stall, yes I agree. Having been
signed off for full-scale aerobatics in my tender years, I can vouch for your observation
about forward speed. On the other point, I would challenge anybody to see the
"quiver" or stall buffet on a pattern plane. Even when you are INSIDE the plane,
you can feel it more than actually SEE the buffet on the wings. The only time I ever
"saw" the buffet was in a full-scale sailplane that had metal wings and at the
buffet you could see the metal "shimmer" out near the tips. But on a pattern
plane at 150 meters? Gimme a break...(no pun intended) John Ford
a)All planes(except Burt Rutan's stuff) will have a pitch down break. The speed(or angle of attack) required for that to happen will vary from plane to plane. Also, the elevator deflection required to achieve that angle of attack is a factor. Most of the time one or the other of these factors is missed by the control setup, or the pilot's technique. I haven't seen an instance where this couldn't be fixed. Sometimes, a faster rate of deceleration can do it, but with the appearance that the plane is climbing, which isn't good(at least to my eyes). b)Even though there is a crosswind, I was raised to believe that the plane must be tracking straight at the moment of the nose-down break, otherwise the "one point for 15-degree rule" kicks in. The nose MUST fall BEFORE the wing raises one way or the other. c)Attitude and track while in the spin doesn't count, but the spin recovery must be executed so the plane is tracking STRAIGHT down for a visible line. This is sometime dicey for planes that tend to spin flatter than others. Obviously, I downgrade "1 for 15" if the wings aren't on correct heading at the moment of recovery. Good topic! John Ford
I have a couple
cents to send in here Jim. 1. Nose high.....Well it states near horizontal track, and
after the spin Near vertical track. This says to me yes it can climb and yes the line
after recovery does not need to be straight down (90 deg to terra firma). 3. Stall speed
and zero ground speed I totally agree this also means that from physics the spin may not
be vertical. it can and will drift with wind or forward momentum. This would have to be
the case cause the plane ain't flyin' only one wing panel is lifting. The big question
then comes on center. Is center the break (YES-always--editor) and then the spin can drift left or right, in or
out. The picture in the rule book show a bam straight down 3 turns and the straight
vertical then recover. I think a note should be put in the rules under the downgrades to
clarify this. 4. I also like Mike's definition easy to understand. Some airplanes stall by
dropping a wing but the other wing does not come, merely the right wing falls as does the
entire plane. I think the key is that the other wing in this case the left doesn't go up
and over. Mike's description explains it very well. Just my thoughts on the spins enough
discussion last year at the NATS I know. Troy Newman
Some things to try
are: o Move CG forward o Pull nose up higher o Believe it or not, it can help to pull up
the nose less. o Switch in aileron flap prior to stall and disengage at stall point to get
a stall. (Allows you to lift nose higher without climbing or using more power. o Last but
not least the famous Canadian down elevator stall. Hope one of these works for you .
Regards, Eric Henderson
As we all know (no trolls, please <BG>), a wing may be made to stall in any attitude. All that is required is for the AOA to increase to a point where there is boundary layer seperation on the lifting surface. If you fly a Hangar 9 Cap 232, setup per stock plans, you KNOW this....
So snap rolling on a downline is very easy. Keeping from entering it with too much SPEED can be the challenge. Different weight airplanes, with different airfoils and moments, require different entry speeds for the snap to be able to recover "on line (track)"...
Generally, you should snap at the LOWEST airspeed that permits a clean break into the snap, and the best recovery line. Unfortunately, since it is a downline snap, you have to anticipate the speed gain, and lead with elevator in the recovery phase to stay on the line. Line drift down (and downwind) is exacerbated by slow speeds, and high headwinds, as during the snap, the airplane really slows and tends to be profoundly effected by any wind.
The reason to have a lower entry speed into the snap, is that less elevator is required to get a good break. This means less loss of airspeed, and greater ease to stay on line.
My technique has been to throttle down on the line preceding the 45 down, to just slightly above spin entry speed....then push onto the 45. If a lot of wind, the radius shouldn't be over pushed, as you'll get too steep a vertical. The snap itself is a very abrupt application of elev, rud, ailerons in that order, and released in reverse order. Releasing elevator last (assuming a one roll Snap) helps with the line. Of course, you must be able to come in with a touch of power IMMEDIATELY after the snap to straighten the line, then get off the power before pulling level for the exit, so that radius doesn't get distorted. It has to match the push down radius, remember.
Techniques will vary quite a bit...and depend dramatically on the airplane....mine works for me.
Bob Pastorello
45 down 1-1/2 snaps: If all that is happening is a heading change and your not still stalled or falling after the snap then its a simple case of inertia. Start your inertia right and snap left. This is easy to do in cross wing conditions rudder slightly with the wind then snap into it. So its ruddering the opposite direction to hold the line wind corrected. Then hit the snap into the wind. On a normal or calm condition it shows a bit more...but lead it with rudder right and snap left or vice versa. If you start the planes inertia in an opposite direction of the snap when you do snap it will come back on line. On a 45 deg line its tough to see the little "cheat" to the left....just hold a little left rudder the entire top half of the 45 and then snap it right and the plane will come out on heading or very close to being right on....
Now this is a secret as a flyer...you have to hide it from the judge. So don't make it obvious. Then to make it a clean stall lots of elevator to start it and in most cases elevator first then rudder and aileron. But lots of elevator and once it starts you can back off the elevator to a moderate amount. And as its coming around inverted on the last half go to a neutral or even down elevator to catch the nose. Its all timing and if done right works like a charm...This method also makes it easier to "hit" the rotations.
As a judge if you see a deviation in the heading of the line its a downgrade. So as a pilot be smooth and subtle and the guy in the chair will have a tough time seeing the correction.
Its almost like cocking a gun or winding up to throw a pitch to Barry Bonds.....the wind up and snap...just make the wind up and snap seamless.
Now if your coming out way too stalled and or the tail is wagging afterward Look at entry speed. Try it slower try it faster try it with a little less elevator and or rudder throw. If it translates or jumps up just as the snap starts your going too fast at entry and have too much energy...If you finish the snap and the planes is sluggish and wallowing your coming in too slow. if your coming in fast enough but the plane just dies and wallows reduce the rudder travel and try again. Perhaps even reduce the elevator.....But personally I find the sticks just don't go to the corners,
its up elevator.......then right and reduce the up.....then neutral elevator or even reversed elevator and dial in the right rotation.
Its all a fluid motion.
On the 1-1/2 snap carry a bit more energy in with you.....Remember a snap is a stalled action....If the plane is falling after the snap more energy will help....Also you going from upright to inverted....what happens when inverted and pulling up elevator? The nose comes down. Its a timing issue you are in the up elevator too long and perhaps too heavy....The snap needs it to start all the plane has got...then ease it out of the snap and when completing the last 1/8-1/4 rotation perhaps you may need a little down elevator.
Troy Newman
Try getting off of the rudder after one rotation, and just let the plane autorotate the second half of snap. You also might want to try some snaps using less than full elevator and rudder. I have a flight condition in my xmitter set up just for snaps. Full up elevator alone will not stall the aircraft, and the rudder throw is too small for point rolls. The reason for this is to not "bury" the snap, but to just get the autorotation started.
Bryan Klein
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