Effects of high alt on our little models.

[MakMov]

Anyone know?

I know it effects my powered planes and helicopters, but what effect does say 5300 ft alt has on a rubber powered plane?

I flew one of my electric helis at 10,400 ft, and it flew but was very lazy.

I think the air where I live is 20% thinner than at sea level.

The up side is the drag coefficent is slight lower.

[ADW 123]

I would suppose most if not all things that apply to a model will also apply to full scale aircraft in a proportionate mannar.

[MakMov]

I would suppose most if not all things that apply to a model will also apply to full scale aircraft in a proportionate mannar.

Put they don't. It is not exactly proportionate. It has to do with physics and molecules. The principle is sound, but when you shrink down something you can’t shrink down the atoms that make up everything include air.

Otherwise, a 1/48 scale Wildcat weight 166 pounds would fly!

So it is not as simple as just scaling everything down.

[MakMov]

no edit feature?

But they don't. It is not exactly proportionate. It has to do with physics and molecules. The principle is sound, but when you shrink down something you can’t shrink down the atoms that make up everything include air.

Otherwise, a 1/48 scale Wildcat weighing 166 pounds would fly!

So it is not as simple as just scaling everything down.

[Steve Blanchard]

MakMov,

Wow that was the best use of smileys ever! This guy right here Placed where you placed was priceless.

Thanks,

Steve

[rayd]

There are people here likely well versed or know more about such things. I know a bit and happen to be here now, so I'll throw in my 2 cents. Am sure others will help. For now, here are some things to consider.

Altitude affects people and things. Our breathing, biological system, things....cars, planes, devices of all sorts get sluggish higher up. Less oxygen, different pressure, colder temperatures, humidity, wind. This affects electronics of all kinds, liquids, gases, contraction. Higher altitudes often adversely affect and slow things down, eg oils turn thicker, ice forms on things, condensation is a factor, things can get heavier. etc. More well versed members can chime in, there are several with much expertise or can lead you..

Now, rubber....gee, as in rubber band power planes? Hmm...your mail carrier ever bundle junk mail in rubber bands? In the winter what happens, soon they snap....rubber does not like cold, whether rubber bands, seals, gaskets....also should condensation form and just a tad of frost perhaps, sluggishness for sure.....add this to thinner air, and the thing just doesn't fly as well as it does as sea level. Well, hope some help here. Note:awhile back, I posted a NASA/NACA site...kinda technical dealing from vintage planes to space shuttle. Check out Chap 2 about de-icing, may be some more info. But do a google or check Wikipedia about rubber.

[cliffm]

You can most likely find your answers under the effects of air density as applied to flight in any flight training instruction books at the library, maybe you can google it too.

[MakMov]

Oh... well... I have a Flight Trianing book from when I was getting my pilots license.

[cliffm]

So after your finished with the altitude anomally you can figure out the c.g. limits on that hellcat.

[MakMov]

yeah, right. I barely got past the c.g. limits of a 172

[goose]

So, where are you that you are 5300 feet ASL?

[MakMov]

Aurora Colorado

[goose]

Thought you might be around Denver. I'm over in Highlands Ranch

[MakMov]

Cool, I know where that is, I work over in Englewood.

[joecrouse]

IIRC back in the day you have to account for the scale when doing testing. Working with something called a Reynolds number.