RCU Forums - New Composite F3A. "NUANCE"

I received this from the designer Mr. Park about his design ideas that went into the Nuance.

Designer's Report about Nuance 170

# competition Nuance.
In all competition a subtle difference of performance, as Nuance stands for, determines to win or
to lose. The Nuance was designed for flyers to feel the delicate difference in flight. I did my best
to design Nuance aming at middle class pattern manias who are able to feel the very delicacy.
The important thing I considered for most well known pattern flyers was to improve stability of flight and
to be accustomed to their flight even if their flight time is relatively little and sporadic.
The stability that I gave weight is weather, especially wind, this stability will give you to help
keep your flight performance constant despite the infrequent practice.
Most of top class flyers fly frequently and their skill is very high too, even if the stability of
the flight is low, they can come over it with their special skill so they tend to design the plane
to modify their demerit such as snap roll. The plane they designed is good and has special merits in
their demerit. The middle class flyers know that expert designed plane is not best suitable for them
and has some difficult parts they are formiddable to overcome.
The Nuance is the plane for most well known pattern flyers who occupy most part of flyers and the point of
design is focused onto them. The flight performance of Nuance is best suitable for them too.
BJ CRAFT will show you specialized new model for top flyers whose philosophy and requirement are
reflected in near future. In addition to it BJ CRAFT will make custom made plane for individual
customer service.

# The flight character and feeling
The flight character of pattern plane is represented by 2 kinds.

The plane which has character of straight flight(straight) : the plane which has strong character to go straight
if the course of flight is directed and power is increased, and has smilar character of the plane which
have accuted swept back wing.

The plane which react positively to control(maneuver): the plane which positively react to the control like
Extra acrobatic plane if pilot add control to the stick of transmitter.
The plane for top class flyers has character of straight vs maneuver 70% to 30%, in this case the
middle class flyers feel that the reaction of plane is somewhat dull because it does not react sensitively
though they put correction control. Most well known pattern flyers tend to prefer the plane which has better
sence of maneuver to dull one because they cann't control accurate direction as well as top class flyers do.

The Nuance's character of straight vs maneuver is 50% to 50%, but designed manwuver of Nuance was
60%, which is the result of giving more weight to the stability. You may know the meaning of straight vs maneuver
is 50% to 50% means what if you feel the character of Nuance and compare it with that of others, even though
individual feeling is different from each other. Straight vs maneuver of Monolog and Prolog is 40% to 60%.

The flight feeling of pattern plane is represented by 2 kinds

Light feeling(backward C/G type) : whatever thing you do, the plane is float in the sky like flight feeling of micro
indoor pattern flight or flight feeling that center of gravity is placed on the aft.

Grace feeling(forward C/G type) : The flight feeling that the plane is cling to the sky as if center of gravity
is placed on the forward, feeling is heavy but stable.

* The terms 'forward C/G type' and 'backward C/G type' is not generally known terms but I named it.
The Nuance was set with the light feeling which most well known pattern flyers are favorite. I think that slow roll is
possible without any control. Flight feeling of Nuance is light but it endures against strong wind if you fly it,
you can feel it better.

# Flight character against strong cross wind.

In the pattern flight stability is essential for all class flyers if so which plane is best suitable for them?
More study is needed to this issue for designers.
Nuance was designed to meet this stability, for this I compouted the ratio of tail volume, side area and front area of fuse in detail to
maintain the pattern track when flyers try to slow pattern flight in strong wind, and also adjusted all three dimensional geometry of
this plane not to be flown by wind or not to be oriented to the direction of wind in all speed.
As a result of this design the balance of Nuance was accomplished successfully to the level most flyers are satisfy even though it is not
perfect level, you may know that the plane is well balanced if you fly Nuance in slow speed in the strong wind.

# Stability of all setting.

The viscosity of air flow in the wing of Nuance is very high compare to that in others, ie I weighed stability
in the sellection of main wing, and designed that the main wing which is the flying base of plane is realized its
presence in the air. The recent trend in design of pattern plane give special weight on the function of snap roll
reducing wing area and viscosity in order to enable snap roll by stall at any flight attitude, which decreases somewhat of the stability of main wing.
Because of this trend flight setting becomes too sensitive to change it every season.
But Nuance enables flight without change of flight setting every season if you set it carefully in the beginning because its stability was improved
significantly compare to the others.
How's the fuction of snap roll of Nuance? The only answer is to fly Nuance.

# The total balance of flight performance
I did not mention the each fuction of Nuance such as snap roll, knife edge, spin, etc, each function can be appreciated by comparing it with
corresponding function of other plane. The other plane which was specialized one function may be best in that specialized, but nobody says about
all other functions not compared. ie a certain function of Nuance is on/above 90% of the best specialized one function. If you specialize
function of snap roll, stability of plane shall be damaged, it is issue of trade-off.If you ask me to design specialized one fuction it is easy
job for me. I gave special weight to improve the balance of overall performance of Nuance applying the ways I mentioned above. I do not know whether
my design concept can be well accepted or not as I launched it right now.

But I will do my best to meet your favor and hope that all users of Nuance will talk about the specialized function based on their experience
and want to hear from them that the total performance of Nuance is much better than that of other plane specialized to only one function.
Also hope you will agree that Nuance has excellent flight performance compare to its price and you will know that Nuance has a couple of differentiated
good characters that other plane does not have.

# About landing gear
Landing gear of Nuance excluded cannard fashion which is a recent trend, because it does not give any aerodynamic effect to Nuance as Nuance has
largest side area out of 2*2 pattern planes.
The shape of canopy was designed with forward position having its smooth curve line. which adjusts prop wash too, as a result of that, Nuance does not
need cannard type landing gear, which not only shows its demerit but shows little adjusting role of prop wash.
Landing gear for Nuance reflcted B.J. CRAFT's technology is very light and elastic one, which is proper to all 2*2 pattern plane.
# Fix of servo for horizental stabilizer
Use mini servo, whose enough torque is on/above 3kg. As Nuance is backward C/G type, It is better for you to move elevater with small control throw.
When you set linkage do as shown in the picture, horn and servo torque palte must be paralleled and the angle between push rod and servo torque plate
must be over right angle as shown on the picture. This setting is a mechnical device to give down throw instead of electronic device, which is easily
influenced by its circumstance. In maiden flight if you set it on the picture, set control throw at 80% in transmitter without any special setting and then
fly it.
# Fix of servo for rudder
The torque of servo must be on/above 8kg and be good neutrality,the speed of it must be slow on/under 0.19 sec. If you use servo faster than this speed, you
may better to reduce the servo speed in transmitter rather than use of Exp. When you find your proper control throw, if you see fish tail, put sponge double
side tape between servo and side pannel like gyro setting of hellicopter. All of these measures substitute long wire linkage.
But my prototype Nuance was no trouble at all, to achieve these I used JR DS8425 servo having speed of 0.19 sec. and 14MZ transmitter.
If you remake rudder servo with long wire linkage do it as you like on your own responsibility. In this case you must check C/G again, you may know that
location of battery mount shall be changed and be hard to put battery in/out.
In maiden flight if you set it on the picture, set control throw at 80% and 60% 0f EXP.

# Fix of servo for aileron
You can use aileron servo with your favorite style. The point of setting is to set rate of snap roll in your style and length of torque plate can be
used by 17mm- 25mm. Recommended length is around 20mm.
If you want faster rate of snap roll, only you have to do is to extend the length of torque plate and stopping is obtained as soon as you release stick.
You may better to set enlarged degree of throw for exclusive use of snap roll as Nuance was designed to give weight on stability of plane.
In maiden flight if you set it on the picture (20mm) set control throw at 80% and 20% of EXP / Snap control throw at 100% or 120% and above 40% EXP.
# Fix of motor mount
Front fixing type of mount was adopted for Nuance, but you can change it depending upon your motor.
The nose side of fuse is strong enough for inrunner type motor, if you need stronger one depending upon your motor, reinforce it on your responsibility.
# Confirmation of center of gravity
You may start at 260mm from the rear corner of canopy (33% MAC) as Nuance was designed with backward C/G type. You can move C/G aft by 20mm and forward by 10mm.
# Assembly of battery mount
After your confirmation of C/G you should assemble the battery mount in trial, put battery in the fuse and confirm C/G again, then fix the mount.
# Flight setting
Basic incidence of Nuance is 0 dgr in horizental stab, 0.2 dgr angle of attack in main wing, 2.5 dgr in right-thrust, 0 - 1.5 dgr in up-thrust.
-Setting center of gravity
Start your flight with designated C/G.
As Nuance was designed with backward C/G type, you may see that tail of plane is a little lowered (that is perfect level or slight float in level flight)
when you make deep bank turn.
If you move C/G toward front, the maneuver of flight becomes dull. if move it further to the front, dull phenomenon is accellerated.
Zhuhai Guang China where designer performs test flight is located about tropic of cancer, and temprature and humidity are very high.
If you are located northern place from my place or southern place from tropic of capreconus, the C/G may be moved to a little front as aerodynamic lift force
becomes larger.
The C/G recommended by designer is 33%-35% of MAC, but you may find out C/G point which is most suitable for your circumstance. I also recommend that you may
be better to move C/G toward aft/front untill you see the facts I described in the above deep bank tern because Nuance was originally designed backward C/G type,
Nuance keeps directed pattern line without being blown by wind even if the C/G moves to relatively rearward.
If Nuance is not suitable for you because the flight feeling is too light due to its aft C/G design, you can sellect Prolog or Monolog designed and manufactured
by BJ CRAFT, whose designed C/G is forward type so it shall show you better performance if you move C/G toward front as much as suitable for you.
- Choice of propeller
You should chose the propeller of Nuance whose diameter is long and pitch is low because its lift force of main wing is very strong, it changes extra power
into speed so I partly adopted recent design trend which give drag to the plane so reduce the speed of plane.
Thanks to high efficiency of Nuance it consumes 2,200-2,500mah in F3A P-13 while others consume 3,000mah in the same. It is better for your control of down
speed to use propeller, for this purpose 20*10-12/ 21*11-13/ or 22*12, relatively long and low pitch, are good, and if you chose lighter one, it
is possible for slow down speed to use dive brake using idle rotation without using brake function of esc.
The propeller of my prototype Nuance is 21*12 wood, its weight is 70g.
The limited design flight speed of Nuance is 120 km/h, so you must chose the porpeller not over the limited speed.
Motor I used is Neumotor f3a , max 68amp, it is over powered for Nuance so used 58amp in my flight, I didn't use brake and flyed with idle setting at the
slowest rotation. My flying style is slow pattern and its distance is 160m, power consumed 2,100mah in no wind and 2,500mah in very strong wind at P-11/P-13.
As a result sometimes I use 3,700mah 10s battery whose weight is only 800g. In this case total weight of Nuance is about 4.4kg.

- Setting power thrust
Nuance was designed that nose moment of Nuance is relatively long so it carrys out straight flight at low throttle. Thanks to the long nose moment, rudder servo should
be located in fuse under stab and fish tail tendency is relatively scarce in spite of direct rudder servo linkage and tend to react quickly to thrust setting.
You carefully consider two points when you set thrust of Nuance.
Point one is thing concerning prop wash. You shall increase right side thrust if the plane goes to left in your vertical upline flight. This way is generally adopted
in thrust setting.
Point two is gyro effect caused by enlarged diameter of propeller and long nose moment. This is one tendency of the gyro effects caused by large rotating object,
it develops at 90 dgr passed the intended direction.
In case of Nuance if the Nuance goes to the left in vertical upline flight, put up-thrust.

If you increase right side thrust to correct the tendency that the plane goes to left in your vertical upline flight, the plane goes to vertical upline flight.
but simulteneously increasing throttle in level flight, develops new tendency of nose going down.
This tendency develops by influence of gyro effect, in this case reduce side thrust that you increased before and increase up-thrust.
If you reduce side thrust, nose down trend disapears, instead of that, tendency of going left in vertical upline flight develops again, to correct left going tendency, put
up-thrust, then the tendency of going left also disappears.
This tendency may not develop when you use different prop and power source. In this case, as gyro effect is weaker than swirl wash, you can correct it putting right thrust
without up-thrust with the same way as general trim chart.
When you sellect prop its diameter is over 21 inches and weight is over 80g, recommended thrust in right side is 2.5 dgr and that in up-thrust is 1 dgr.
At any case side thrust cann't be over 3dgr in order to protect from sudden gyro effect. Swirl wash of prop and gyro effect give influence mutually.
If you use prop which has short length(diameter) and light weight, gyro effect cann't be developed.
Thanks to the test flight of Nuance in thrust setting, even if you do not use counter rotating system, preformance of flight and straight flight of Nuance is much better
than those of other planes.
The tendencies described above are the special character of B.J. Park's design, which is related with nose moment and tail volume. These are shown in the
design of Monolog, Nuance and Prolog, These can be shown in the other designs but they are verified by BJ PARK but not accepted theory in general.

# Usual flight setting
General flight setting includes C/G, control throw and data setting of transmitter and receiver, which are most flyers carry out when they set flight.
# Setting in the strong cross wind
Almost all flyers finish flight setting in the above but Nuance selected one more model of on/above 10m/sec of wind speed from transmitter, and set it to
enable flight in the strong cross wind, this setting significantly improves your performance in your competition.
After sellecting one more setting from transmitter, first, move C/G forward to the front than usual, second, install prop which is proper to strong cross wind
having high pitch. Chose the strong windy day, carry out trial flight on that day, reconfirm the location of battery and determine the size of prop.
After being moved C/G and being changed prop on no windy day, fly plane with the same setting, retermine the control throw and trim, change throttle curve for windy day.
The control throw of Nuance should be set bigger than general setting, Exp remained as unchanged to harmonize with general setting. If you set these in your spare time,
you can be helped very much. If you apply this setting to Nuance, it shows you much improved performance in competition.