How to
Balance Models with a Calculator
Credit MAN May 2001 by Jef Raskin





INPUT R Root >>>9.5
INPUT S Sweep >>>3.0 'note...IF... sweep is forward…THEN… S is a negative number
INPUT T Tip >>>7.75


Q = (R^2 + RT + T^2) / (6 (R + T))
Q = 2.16

P = 1 - [(4Q - T) / (R - T)]
P = 0.48

D = Q + (SP)
D = 3.61
D = distance back from leading edge of wing [at fuselage centerline]

03nov14…

A large indoor fly sight may become available soon so the need to build fun stuff with a theme inspired this project


ROG Military FunScale >>>Preliminary<<<

Build from any plans, any material, any *power*, any covering

Give original model designer and paint scheme artist credit if credit is due.
If its your plan and/or paint please say so :>)

Model must ROG to include but not limited to a card table (ROCT) and/or catapult (ROAC) roll off aircraft carrier

Model must include a pilot figure and carry armament

Max wingspan 23.333 in
Max cord is undefined, as in …have fun!

Other than ‘scale-size’ and ‘aspect-ratio’ the original plan’s ‘by line’ and ‘trade mark’ and ‘MFG logo’ not altered

>>>notes <<<
any power* no liquid fuel at indoor site
any power* indoor CO2 tbd
>>> <<<


>>>models<<<
see PDFs below
How would Hanger Rat lQQk with an A-10 Warthog 50 cal Gatling gun on one strut?

Cadet Fighter lacks firepower, maybe an early deck cannon or cap and ball Colt?

How would GARAMI’S Gull Wing lQQk in Corsair paint and distinctive up-arrow fin and tail hook?
>>> <<<


>>> 06nov14>>>
Naked Baby Bipe in dollar store 1.25 mm foam dinner plate. Fuse to include fin is double for 2.5 mm, stab and wings are 1.25 mm. Image balanced for best glide with 00 buckshot weighs a tad less than one-half oz.

2014Oct23

Joker03-on-the-wings-of-a-Radian
Allup=(model-29.5oz)+(camera-8oz)=37.5oz

1)orange
CraftAir
Butterfly
99-inch/916-sqin
mfg-suggest-flying-weight=50oz
my-all-up-to-date=63

2)white
ParkZone
Radian
78.7-in(2-meter)/tbd-sqin
mfg-suggest-flying-weight=30oz
My-all-up-to-date=0
...
Edit…11sep10
Triple-boomer-on-2m-Radian-wings;
Allup-maiden=30.5oz
WOW!-Such-a-sweet-combo
Winds-apx-3-5-mph
STOL?
TO=Hand-launch
L=rather-tight-pancake-spiral..with..absolutely-NO-inboard-wing-stall
Conclusion…NO-aileron-mod-required-for-lite-air-tight-turns.
Three-flights-and-two-thermals-and-forty-five-minutes-later-final-landing-
with-75%-remaining-on-a-3-cell-1500mAh-lipo….a-keeper-for-sure!…:>))
...

3)gray
Multiplex
EasyStar
54-inch/372-sqin
mfg-suggest-fly-weight=24oz
my-all-up-to-date=40

Triple-boomer…
On-the-wings-of-an-EasyStar

Note-adjustable;
CG
Incidence
Down-thrust

Note-size-of
Tail-plane
Payload-bay

The-EasyStar-boomer-setup-has-worked-out-so-well
I-have-on-order
Wings-of-a-Radian-(2-meter)

My-motor-mod

20aug10
EasyStar
Removable-tail-plane-allows-no-glue-fuse-sides:>)
First-glue-fin-to-stab
Hot-glue-soda-straw-to-reinforce-holes-for-#64-rubbers

Like this... Ali/rud on same servo.

How to ...
Make a HIGH power shunt for box store DVMs and
Extend the range of most box store DVMs past 10 AMP max

This technique does not apply for AC power measurement

This technique allows different props to be expressed in terms of Watts;

From FIG 2...
First measure resistance and Volts
Second calculate current, I = E1 / R1
Third calculate power, P = E2 X I


CAUTION,
lipos exhibit a potential fire and or explosion hazard if output wires short (touch each other).

Never ever allow lipo wires to touch, the lipo will dump MAX AMPs into zero Ohms, weld wires together, chemical avalanche, puff up and may burst into flame and explode.

Although I give two examples below,
DO NOT wire up these example.
DONOT wire up R LOAD equal to zero Ohms.
These examples are for other purpose.



For direct current only

>I< current, Ampere, AMPs
>E< Volt
>R< resistance in OHMs
>P< power in WATTs


I = E1 / R1 … “ / “ …. E is divided by R

P = E2 X I …. “ X ” …. E is multiplied by I

R1 is called a shunt resistor and RL the load resistor.
R1 is usually measured when the shunt is cold (FIG 1).
The shunt will get hot under test conditions and its value will change
This unknown change is critical with respect to repeatability so the shunt power handling character must be addressed.

DONOT wire this example. DONOT connect you lipo at this time.
This is an example only to define your...Continue Reading

“”Is it possible to run two motors at the same time at different speeds, or with one motor on and one motor off?”” Bob

https://www.rcgroups.com/forums/showthread.php?t=755466

>YES< can be done.

Two motors, two ESCs, different speed (delta yaw) or
one motor off, the other full on or in-between (adverse yaw, 4D and beyond ).

The good news, this can be accomplished with the ole BCR (Before Computer Radio).
The computer radios MIX / STICK potential add more functionality.

Connect ESC-1/motor-1 to THR CH3 (normal)
Connect ESC-2/motor-2 to RUD CH4 and cut ESC-2 red wire

AT THIS POINT, ‘normal’ rudder servo function is lost.
The GOOD NEWS lighten the model, remove rudder servo and cross couple rudder to aileron like we did back in the ole-days BCR.

AT THIS POINT, the old rudder stick, now NEW THR STICK is spring loaded at half throttle.
I suggest, disable spring / Phillips screwdriver / long nose pliers.

For the more adventurous than me … ...
Do not disable spring, SUB TRIM motor synchronization with ‘trim’ lever.

Computer radios MIX, STICK, EXPONENTIAL and SUBTRM only add sketty-eight more options.

Control Surface Differential

Control surface attuned...
Computer radios make this a cinch.

Life is a little more complex for some of us with BC radios (before computer).

Never could find my trig-table let alone remember how to use it. An analog computer is much less complex, no math mistakes to deal with, more fun to build and play with than a book of tables.

Pic-1
Top, the perfect set up, output is equal to input
Middle, several options
Bottom, mine usually lQQk like this

Pic-2
Scrap foam, stickpins for pivots and protractor required to build analog computer
I suggest keep linear measuring units the same (such as inches red tic marks), wheels seperated 10 inches

Pic-3
Pointer on right is output >and< side view of control surface
Output Equals Input

-4 es –5 output result for an initial input set to 45

To share an observation, some nickel knowledge
and first hand experiments with respect to
model airplane electric motors.

How I got more speed for less AMPs;

Volts equate to speed.
Amps equate to duration.
Watts equate to work accomplished (Watts per pound).

Watts equal Volts times AMPs
(10V X 15A = 150W)

Best investment I ever made…
Two box store digital multi-meters.
Picture and diagram below.

With respect to propellers;
Shorter and/or less pitch usually equate to fewer AMPs >at full throttle<
AND higher rpm, more speed.

Smaller props develop higher rpm for two reasons;
1) less mass accumulated on the motor
2) fewer AMPs mean more Volts (in the form of power) available to the motor due to less internal power waste building up nothing but heat inside the battery and ESC.

Empirical static test proof … different propellers;
https://www.rcgroups.com/forums/showthread.php?t=728162
post 7 in order to selected a prop that was most efficient AND not blow my motor or ESC or puff lipo at MAX throttle.

Battery discharge specification is based on its internal resistance and how much heat it can dissipate before smoke is generated.

The higher the AMP flow through ‘any’ resistance the more heat generated.
Power (in Watt) equals AMP [squared] multiplied by resistance.
IF a component (battery for this example) has an internal resistance of 0.2 Ohm then power waste at 15 A discharge is 15 X 15 X 0.2 = 45 Watts of nothing but heat.




Gramps :>)

Jim,
I can not figure how to post images to your PM
'text' was sent in PM to you.

Gramps

'myguys' credit G Larson

test