aircraft polar model - RC Groups
 This thread is privately moderated by ciurpita, who may elect to delete unwanted replies.
May 15, 2012, 09:08 PM
greg
Discussion

# aircraft polar model

rough estimate of 2-33 polar
Code:
```function calcCdi (Cl, Ar, k)  {
return k * (Cl^2) / (Pi * Ar)
}

# ------------------------------------------------
function getAirspeed (cl, area, weight)  {
return sqrt(weight / (0.5 * Rho * area * cl))
}

function getCl    (airspeed, area, weight) {
return weight / (0.5 * Rho * area * airspeed^2)
}

# ------------------------------------------------
function getLift  (cl, airspeed, area)  {
return 0.5 * Rho * area * cl * airspeed^2
}

# ------------------------------------------------
function gen (Weight, Area, Ar, Cd, col)  {
v0     = int(getAirspeed(CLmax, Area, Weight))
v1     = int(getAirspeed(CLmin, Area, Weight))
N      = v1 - v0

printf "## airspeed  %8.4f - %8.4f\n", v0, v1

for (n = 0; n <= N; n++)  {
airspeed  [n]  = v0 + n
cl        [n]  = getCl(airspeed [n], Area, Weight)
cdi       [n]  = calcCdi(cl [n], Ar, 1)

induced   [n]  = getLift(cdi [n], airspeed [n], Area)
parasitic [n]  = getLift(Cd,  airspeed [n], Area)

lift      [n]  = getLift(cl [n], airspeed [n], Area)
drag      [n]  = induced [n] + parasitic [n]

Ld        [n]  = lift [n] / drag [n]
sink      [n]  = 4 * airspeed [n] / Ld [n]

airspeed  [n] /= 5280/3600
}
}

# ---------------------------------------------------------
BEGIN  {
Pi     = atan2(0, -1)
Rho    = 0.002378       # slugs / cu.ft.

# general
CLmax  = 1.5
CLmin  = 0.175

# 2-33 parameters
Empty  = 600            # lbs
Cargo  = 300
Weight = Empty + Cargo  # lbs
Span   = 51             # ft
Area   = 220            # sq.ft.
Ar     = 11.85

# estimates
Cd     = 0.007

gen(Weight, Area, Ar, Cd)
}```
a 2nd polar plot is added. It shows polars with weight increases equivalent to
lift increases necessitated by bank angle increases of 15, 30, 45 and 60.

It also shows AOA/Cl corresponding to min-sink speed in each plot.

### Images

View all Images in thread
Last edited by ciurpita; May 16, 2012 at 08:12 PM.
 Sign up now to remove ads between posts

 Thread Tools

 Similar Threads Category Thread Thread Starter Forum Replies Last Post Discussion Keswick Model Aircraft Club, Ont, CA Hexperience Club Talk 14 May 29, 2012 09:52 PM For Sale RC Model Aircraft LOT (TXs, RXs, servos, parts) MQ_FUN Non R/C Items (FS/W) 4 Apr 04, 2012 12:48 AM Discussion GPS Location System for RC Model Aircraft l.brisebois Electric Plane Talk 1 Mar 20, 2012 11:12 PM Discussion GPS Location System for RC Model Aircraft l.brisebois RC Flight Events 0 Mar 20, 2012 06:51 PM For Sale THE INCREDIBLE HULK Model Kit Polar Lights Aurora MIB! Mikey 68 Non R/C Items (FS/W) 0 Apr 19, 2011 06:10 PM