Ryan NYP

[Prosper]

Very interestin'. Re. my previous post about getting an urge to model NX211 every summer, the tiny tailplane is one of the off-putting factors. Bill Dennis has said that he has few qualms about small tailplanes (my interpretation of Bill's words), and I agree with him - I've flown rubber scale models with tailplanes 14% of wing area without problems - but I don't remember if NX211 even attains 14%.

Stephen.

[TheLurker]

Bit of arithmetic and redrawing this evening. 

Running DeLoach's approximation over various permutations of tail plane size and it looks as though a 9% oversized (by area) tail plane will be about right for stability and won't look stupidly large.

I've increased the span rather than chord as I read somewhere (no, I really can't remember where), but it was years and years ago that a span-wise increase was more effective than a chord-wise increase.  Whether that's true or not I think a span-wise increase is less jarring to the eye

For those who need to know these things.

A 9% increase in area increases Vh (TVo) from 0.6 to 0.74 and gives an approx. CG position at 42% root chord.

A 4.5% increase in area increases Vh (TVo) to 0.66 and gives an approx. CG of 40% root chord.

DeLoach advises that for FF scale models that 0.66 <= Vh <= 0.75 is likely to give best results.

Of course this is all "wet finger in the air" with a large dash of haruspexy thrown in, but it's a bit better than wild guesses.

[Jmk89]

I haven't seen 'haruspex' since high school Latin classes (when it was not unusual for me to be thinking about something I'd read in the latest AeroModeller rather than the third declension).