Aircraft design in a nutshell

[Manu DM]

Hi to all home-made model enthusiasts.

Here is a new webpage I built to easily design any fixed-wing model aircraft; it's called "Sweet Purple Planes" :

http://img111.imageshack.us/img111/8073/sppqq5.gif (http://imageshack.us)

Computation includes MAC, CG, stability, flight speed and Power input.

Moreover, a sketch of your project is drawn automatically :D .

It should work well on most common browsers (IE6, FF1.5 and Safari).
However, if you detect any bug, let me know !! :rolleyes:

The page is here :
http://zzmanu.club.fr/spp/spp.html

If you like it, don't forget to send pictures of models designed with SPP !

Bye,

Manu :)

[LiveInAutoPilot]

Haha, awesome. Now I'll never sleep. :-p

[dustn]

That was actually me posting there.^

If you get this moved to the slope or HL forum, it would get a bit more attention I think.

Bryan

[Manu DM]

Indeed, "Modelling Science" does not seem to bring much people ... too bad :rolleyes:

Ok to move to glider forums, but airplane folks might be intersted, too, don't you think ?

Multiple posting isn't alowed, is it ? :rolleyes:

Or maybe I could just put a short topic linking to here in some potentially interested forums ? :confused:

Manu.

[JetPlaneFlyer]

I see that there is no input for wing section, decalage angles, CG position etc.... I'm wondering how it can predict stuff like glide ratio and min flying speed without this info (esp. wing section) :confused: . plus parasitic drag would have a major influence on glide ratio too.

Still a lot of fun to play with though :D

[Manu DM]

There is obviously an input for CG position, and par. drag is considered in computations (using common Fuse drag coefficients).

Concerning airfoil section, SPP uses polar curves averaged for usual airfoils (SD 7037, RG 15, Se 4083, E387 for gliders, Clarck Y, NACA 2415, E 168 for planes).
It was a deliberate decision to simplify inputs, as airfoil input will usually only slightly modify output performances figures.

I will place some details on those issues in "formulae" as soon as possible.
Consider reading the Manual and FAQ pages as you will already find some useful informations on implemented computations.

Have a nice time with SPP ! :)

Manu

[danfield]

Hi Manu

Having a bit of fun with your program. Looking through your FAQ's under Planks, you make the following statement, can you offer some details and or where do get this information? I have been looking and have not found guidelines on A/R for Planks just yet. It's the below 8 that's in question, namely around 3 meter Span. Maybe you are just referring to say 60" models?

Regards
Dan

***
As rules of thumb, plank (unswept) FWs usually need a significantly reflex-cambered airfoil (positive Cm0), as well as a relatively low wing aspect ratio (usually below 8).

[Manu DM]

Hi Dan,

Glad to have messages from SPP users. Send pictures of models for the gallery, too !

These rules of thumbs come from old pragmatic papers on FW design in the french RC litterature, and are not deep-theory-based. However even at higher wing areas, planks tend to have lower AR, as not only Reynolds number, but also stability issues are involved, compared to regular gliders. Namely there can be pitch oscillation problems with some airfoils at high AR. As a side effect, electric plank models, which have higher inertia around pitch axis due to higher fuse mass, seem to tolerate higher AR without problems.
Probably the best source for info on that is B2Streamlines and aerodesign.de websites.

Cheers,

Manu

[The.Timinator]

Hi Manu

A fellow Slope addict pointed me at this thread.

Thats a cool tool, and, it agrees with my own (relatively crude) attempts to do CG calcs etc.

I'm into Flying Wings too at the moment and have been playing a little this evening - too much really, should have been fitting the servos into my Acacia...........

Don't lose faith mate - go to the Slope edge and feel the Force!

Cheers and thanks for the work

Tim