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Miscellaneous Items

BMFA Safety Guidelines
(Just remember who is responsible for your models safety. )

BMFA Model Flying and the Law

BMFA Insurance Cover - First Time Inexperienced Flyer

Club liability insurance can be extended to cover first time visitors to your Club who have no previous experience of model flying but are seeking to try out model flying prior to joining your Club. However, in this case cover will only be in place when the flights are being personally supervised by a nominated Club member approved by the Club Committee. No charge will be made for this additional cover; however, cover will only be in place for a maximum of 3 days for any one first time flyer. After this initial 3 day period the first time flyer must arrange his/her own third party public liability insurance cover, by joining the BMFA, prior to undertaking any further flying activity at your Club site.

A i r c r a f t   S u p e r   C a l c u l a t o r    6 . 1
(Mean Aerodynamic Chord, Neutral Point, Center of Gravity, and Weight & Balance)

MAC And Neutral Point
If no changes are seen in results after updating an input field,
then click BOTH compute/refresh buttons.

use the same units of measure (inches or feet) for all entries!



Center of Gravity (CG) is the point where the WEIGHT of the aircraft is balanced.  Neutral Point (NP) is the point where the AERODYNAMIC FORCES generated by the wing and tail are balanced.

Placing CG 5% - 15% of MAC in front of NP creates a longitudinal (pitch) stability called Static Margin. A lower margin produces less stability and greater elevator authority, while a higher margin creates more stability and less elevator authority. Too much static margin results in elevator stall at take off and landing.

25% - 35% MAC is generally accepted as a good range for the CG of a conventional tailed aircraft where the AC of the wing is at 25% MAC.

The Equations

Wing Sweep, C =
(S * (A + 2B)) / (3 * (A + B))
MAC (length) =
A - (2 * (A - B) * (0.5 * A + B) / (3 * (A + B)))
MAC location, d =
Y * ((A - MAC) / (A - B))
wing area, WA =
Y * (A + B)
tail area, TA =
YY * (AA + BB)
wing aspect ratio, ARw =
((Y * 2) ^ 2) / WA
tail aspect ratio, ARt =
((YY * 2) ^ 2) / TA
Tail Arm =
 (D - wing AC) + tail AC
tail volume, Vbar =
(TA / WA) * (Tail Arm / MAC)
NP (%MAC) =
0.25 + (0.25 * sqr(sqr(ARw)) * Vbar
ideal CG (%MAC) =
 NP - Desired Static Margin
Moment (total) =
 (Lt wheel Wt * Lt Arm) + (Rt Wheel Wt * Rt Arm) + (Center Wheel Wt * Center Arm) + (Pilot Wt * Pilot Arm) + ( Psngr Wt * Psngr Arm) + (Fuel Wt * Fuel Arm)
actual CG (%MAC) =
 ((Moment / Total Wt) - (Datum2LE + C)) / MAC
actual static margin % =
 (NP - actual CG) / MAC * 100

 

NOTE:   This calculator can be distributed by permission only simply by copying the contents between the first and last <table> tags.  Javascript equations and functions are fully contained within it.  DO NOT REPURPOSE BY EDITING any html or javascript contained herein without permission.

email Dean A. Scott at dascott / at / southern / dot / edu to obtain distribution clearance and repurposing/reuse permission.

 

 

 

CG / MAC Calculator adapted from the Public Domain. Neutral Point and Weight & Balance Calculators developed by Dean A. Scott (c) 2005, all rights reserved.  Use with permission.

NP equations courtesy Alasdair Sutherland (see C.G. Position article on Bloobird Radio Flyers)

 

 

Enter the following data:
Wing
Tail
Root Chord (A, AA) :
Tip Chord (B, BB) :
Sweep Distance (S, SS) :
Half Span (Y, YY) :
Distance between wing & tail root LE's (D) :
Desired Static Margin
(5% = twitchy  20% = mushy  10% - 15% recommended) :


Weight And Balance
 
Weight
Arm
Left Main Wheel :
Right Main Wheel :
Nose or Tail Wheel :
Pilot :
Passenger :
Fuel Tank (gallons of gas) :
Datum Point from Wing Root LE :
Wing Root Chord (A) :
Sweep length at MAC :
MAC length :
For more accurate results, enter the values for Sweep Length and MAC
computed from the "MAC and NP" calculator above (shown below in yellow).
Calculated Results
Mean Aerodynamic Chord (MAC) =
MAC distance from root chord (d) =
Wing Aerodynamic Center aft of root LE =
Ideal Center of Gravity %MAC =
Actual Center of Gravity %MAC =
Ideal CG aft of root LE =
Actual CG aft of root LE =
Actual CG from main axle (neg. is aft) =
Neutral Point %MAC (NP) =
Neutral Point aft of Wing's root LE (NP) =
Distance between Ideal CG and NP (E) =
Distance between Actual CG and NP =
Desired Static Margin % =
Actual Static Margin % =
Gross Takeoff Weight of Aircraft =
Empty Weight of Aircraft =

Other useful results
Wing Area = 
Tail Area = 
Wing Apsect = 
Tail Aspect = 
Wing Taper = 
Tail Taper = 
W sweep C = 
T sweep CC = 
Tail MAC = 
T MAC dist = 
Tail Arm = 
Vbar = 
Lt wheel mnt = 
Rt wheel mnt = 
Center wheel mnt = 
Pilot mnt = 
Passngr mnt = 
Tank mnt =  
       
       

35MHz Frequency Allocation Chart

UK Airborne Frequency Allocations 35MHz
35 MHz. Freq. Pennant No. 35 MHz Freq. Pennant No.
34.950 55 35.130 73
34.960 56 35.140 74
34.970 57 35.150 75
34.980 58 35.160 76
34.990 59 35.170 77
35.000 60 35.180 78
35.010 61 35.190 79
35.020 62 35.200 80
35.030 63 35.210 81
35.040 64 35.220 82
35.050 65 35.230 83
35.060 66 35.240 84
35.070 67 35.250 85
35.080 68 35.260 86
35.090 69 35.270 87
35.100 70 35.280 88
35.110 71 35.290 89
35.120 72 35.300 90

Propellor Selection Chart

Propeller Selection Guide

cu.in

2-stroke

4-stroke

.10

 7"x4" - 7"x6" -
.15 7"x4" - 8"x4" -
.21 8"x6" - 9"x5" -
.25 9"x5" - 9"x8" 9"x6" - 10"x6"
.28 9"x5" - 9"x8" -
.30 - 10"x6" - 11"x4"
.32 9"x6" - 10"x6" -
.36 9"x6" - 10"x6" -
.40 9"x6" - 11"x6" 10"x7½" - 12"x6"
.45 10"x6" - 11"x7" 11"x6" - 13"x4½"
.51 10"x6" - 12"x6" 10½"x8" - 12½"x6"
.60 11"x7" - 12"x8" 11"x8" - 13"x6"
.75 12"x8" - 13"x6" -
.90 13"x6" - 14"x6" 13"x6" - 15"x6"
1.20 16"x6" - 18"x10" 14"x11" - 18"x6"
These figures  are for guidance only.
Please refer to the engine manufacturers recommended prop. sizes

RC Flight Unlimited - Helps, Hints and Tips

A very useful website covering many aspects of modelling e.g. Model Design, Engine Break-in Preocedures etc.

Setting up tuned pipes.

A comprehensive guide to tuned pipes by Andy Ellison.

Getting Started in Radio Control Model Aircraft.

If you wish to feature a website, or have useful information please feel free to email us.
Drop us an e-mail, if you wish to be notified of the next site update.

General Selection of RC Videos

Just a small selection of the many RC videos that are available on the internet.

The effects of G-force on Steve Beatty whilst experiencing a flight with the Blue Angels.
(Not a RC video as such but great fun to watch)

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