Plane Performance Predictor
This is a fairly simple attempt at a program to help design/analyze (electric) planes.
It will open its own window.
If you have less then an 800 x 600 display, then you may want to try the
JDK 1.0 version.
Please be patient as This may take a little while to load, up to
Java must be enabled to use the program on this page.
Java 1.1 is required, but if this does not work for you,
try the JDK 1.0 version.
Feel free to bookmark this page.
This page and this program are very preliminary.
All suggestions and comments welcome. Complaints will be ignored.
This program was not ment to replace
but as a programming excersise and to allow more
people access to some form of the performance calculations so
necessary for successful electric flight.
This program compiles several formulas that I have taken from
the net (such as
(link currently down),
and the articles on the Aveox site.),
from Bob Kress's article Electric Flight Model Design in Flying Models,
and Model Aircraft Aerodynamics by Martin Simons.
All formula are approximations - some are better than others.
The current, voltages, powers, and RPM are all fairly accurate.
Others less so.
- There are a limited number of choices in each section so far.
Feel free to type in your own values. However, there is no way
at present for you to save values you have entered.
- Battery and Prop names are the Garrison Aerodrome
- Cell mass does not include the extra weight required to make
them into a battery - please include such in the Wire mass entry.
- Resc should include such things as connector, wire, and fusing
losses, if known.
- ballast is a placeholder for things like payload or nose (tail?)
- Prop weight should include the spinner/prop adapter.
- Kprop is normally 1.31, but APC props use 1.11, and MA Wood (not electric) should use 1.7.
- All masses for everything except the cells are very approximate.
Any 'zeros' are probably due to my not having any information.
- BCS stands for Best Climb Speed and is the speed which produces
the best climb angle.
Climb angle is from the Kress article and seems a bit optimistic.
The article claims the formula is only valid for less than about
30 degrees, so it grays out over that number. Also, it will
change to orange
at a value which feels low for my own plane -
your milage may vary. At very low values, it will turn to
indicating a plane which is probably painful to fly, if it's
CPF stands for Climb Performance Factor and is defined by Kress
as a factor that indicates "the best steady climbing ability
of the model." He gives the example of a good model having CPF=6.38
and a poor model having CPF=2.10. You might use CPF as an indicator
of how well matched the model, prop, motor, and battery are.
- Pitch speed will change color if it is less than the recommended
3x stall speed.
- Watts/pound is based on motor input power. It will change to
for less than the rule-of-thumb 50 watts/pound and
for less than about 30 watts/pound.
Run time simply takes the capacity of the cells and divides it
by the current. This is overly simplistic, but I do not have
a better way of doing this yet.
- Level Flight is the power required to maintain flight.
L/D max is the maximum Lift to Drag ratio.
CL(BCS) is the required Lift constant at the best climb speed
in order for the plane to support it's own weight.
All suggestions are quite welcome. A source for a good approximation formula
for climb angle, climb rate, and drag and/or max speed would be
I do take requests for items to add to the menus.
All decisions as to what to include are entirely mine.
This page brought to you by William Sears
Please address all questions or suggestions to me.
This program is free to use, but you may not copy it, modify it, or sell it in any
way. Feel free to link to this page from your own site.
If you wish to support this program, I do web pages, or you can buy
Garrison Aerodrome kits (I help make them),
or donate any models or modeling items you wish.
I mostly do this stuff to support my R/C hobby anyway.