Scale question - "%" does it really mean anything?

[SleepyC]

Hey guys...

This may seem dumb, but I couldn't sleep last night and started thinking about some things.

The thought I got stuck on was the concept of scale... and the weights.

Snap and others are building the 50% edge.
They are saying it should weigh around 50 lbs... and use a motor that has 24 hp.

A real Edge weighs 1527 lbs and has a 327 hp motor.

So doing the math... the size may be 50% in inches,
but in weight and power the scales are Insanly in our model's favor.

The weight is around 3% of the REAL edge. (just 47% short of being scale)
And the models motor would have 7.5% of the real aircraft power.(just 42.5% off scale)

But with the models lite weight, we have redculas power to weight ratios come paired to the real deal.

Its no wonder we can do the things we do with our models...

Just something to think about.

(Also the math was done in my head... so I'm sure if someone wants to pull out a calculator, exact numbers could be had)

[Vic3D]

I think we should go scale on the power side as well. fg57

[rodman]

	Quote: Originally Posted by SleepyC
	A real Edge weighs 1527 lbs and has a 327 hp motor.

Wow you did the %'s in your head?
I had to use a calculator to figure out that the plane would weigh
763lbs and need a 163hp engine.

I dont think it would roll on a grass runway at that weight. lol
Not to mention you would need 5 guys to help you load, and unload the thing.

So the question should be how would the real plane fly at 3% of its current weight?
Hmmm

[Colonel Klank]

Sleepy: You have simply proven that you are one of the worlds great thinkers. When Samuel P. Langley designed his "Langley Aerodrome" in 1897, he built the test model approximately 1/4" scale and it flew successfully along the Potomac river that borders Virginia and Washington D.C.
His largest mistake was simply taking the model and sizing it up four times to get one that would carry a man. The problem with scale is, that there are sets of numbers called 'Reynolds Factors" that govern different sizes of the same model.
Simply put, if you scale up a model 4 times and use the same structure, it will fall apart, which is what the man carrying Aerodrome did.
Steve, you ought to hook up with that Schlermy Beckerman dude and exchange e-mail addresses.

[SleepyC]

	Quote:
	Steve, you ought to hook up with that Schlermy Beckerman dude and exchange e-mail addresses.

Schlermy Beckerman is truly a class act. But I'm sure his intelligence surly surpasses my understanding of most things.

Even with the reyonolds factor, our models are still WAY over powered...

Not saying thats a Bad thing... At ALL... just saying...

Hey man... when you have an bad addiction, there are no boundries of what part of the hobby your brain will fixate on.

So come on all you engineers and such.. lets drop the math, and calculations... someone teach me!! That way I can say I IS EDGE-A ma Kated!

[Vic3D]

Also remember that air density is way bigger related to the plane when it's a full-scale aircraft, so the lift factor is greater by area than on our models.

This is actually a very interesting topic. Notice how a 50% aircraft uses a 36 inch propeller and it is over-powered compared to the full-size, BUT if we were to scale the prop to 100% it would be a 72 inch prop. I think full scale airplanes have bigger props than this.

[SleepyC]

YEa MAN!! I love it.. we are using our GRAY MATTER!!

[JimC-MD]

Here is a test for you sleepy. Let's figure out the average weight of a pilot and put the scale amount in one of these planes. I bet they would fall apart. That is one of the areas that allows us to build them so light. We do not need to carry the same payload.

Now take this scale discussion to a line of thinking I had the other day. What about the size of the figures flown at a typical IMAC contest? Are they drawn to the scale of the airplane flying them as compared to the full scale? It appears that they are flown much larger than a full scale bird as this makes it easier to hide corrections. If a full-scale flew them at that size, they would likely run out of power and a loop would be a mile in diameter. Should we give a presentation bonus to pilots that can actually fly the figure accurately in scale dimensions? Perhaps this would make it more interesting for spectators to view. Any full-scale pilots out there that can give us average numbers for the size of figures and how they would compare?

BTW, I am glad I am not the only one that has these crazy thoughts running through their mind

[wizard]

The scale weight of the pilot would be more than the AUW of the plane.

[Ion01]

I am sure there is some sort of equation for making a truely scale aircraft as far as all things are related but I do understand that, at least when drag racers are involved, that if all things are equal, if the weight is double then the amount of horsepower needed to produce the same acceleration must be squared. So if it takes 5 horsepower to move a 25 pound model 0-60 in 6 sec. it will take 25 hp to do the same to a 50 pound model, and then it will take 625 hp to move a 100pound model at the same acceleration. These are just made up figures but you get the idea of how it works. I am sure all other factors regarding scale work in a similar fasion but may take a more complicated equation. I am also sure that even if the correct equations were applied that the 50% edge and all other 3d craft are insanely overpowered.

[WOODisGOOD]

Sleepy stop thinking and get your plane finished.

[JeeUm]

	Quote: Originally Posted by WOODisGOOD
	Sleepy stop thinking and get your plane finished.

Hahahaha. Yeah, what he said!