These guys are all leadng you correct...

However, also important is wingloading... you can put a DA100 on your bird and have tremendous power-to-weight ratio... but it'll fly like a rock (if at all).

Truth is... in order to get the VERY best power to weight in an ARF... you need to buy an ARF known to be light and install the higher end powerplant.

A great case in point was the Extreme Flight Yak... 15.5 lbs with a DA50 was aaesome... Maybe around 2:1 or a little over. It's just not feasible to expect more.

In reality, 3D is more about a combination of features. Like in computer games when you develop a character... you get "100 points" to distribute among 4 or 5 attributes.

Well let's do that with an aircraft and set maybe 4 attributes:

Weight
Thrust
Wingarea
Stability


You have 100 points to distribute among these 4 things to get your plane...

Imagine setting them all to 25%... a nice even balance. No one attribute is more important than the other.

But let's say you want MORE power to weight... you might set:

Weight :30
Thrust :30
Wingloading :20
Stability :20

Since you only have 100%, you notice to get a better power to weight ratio, that you need to lower the weight (increase importance) and thrust... BUT wingloading and stability suffer. These are all inter-related... and increaseing/decreasin one attribute will effect the other to some degree.

For instance you want the weight to be lower... Well either it accepts a smaller engine that puts out less thrust, or the airframe is smaller and the wingloading suffers or it's too heavy and the plane want's to snap more.

Let's go for wingloading and stability:

Weight :20
Thrust :20
Wingloading :30
Stability :30

Here we want wingloading and stability higher priority. So we get a larger plane and smaller engine... but now we don't have 3D power.


But occasionally there are airframes that offer good weight and engine ability.

Like the new 74" Yak from Extreme Flight (or like the 68" and 87" were) or Quique 73" Yak. Other options might be the Giant U Can Do, Chip Hyde Tunnel Vision, Fliton Extra, Funtanas, etc.

Planes that are designed ultra light for their size... These planes get "bonus points" like weight and wingloading +10 so you effectively have 120 points total.

An engine can offer bonus points too... like the "who knows when it will ever get here" BME 55 that weghs a good bit less than other 50cc engines. Or the Saito 82 that weighs the same as the 72. Thrust +10


Then there are $$$ points... points you can BUY like lipos, CF gear & spinner, titanium pushrods. that add say +5 to +10 to weight.

I hope this analogy is clear...

Basically the BEST starting point is to select an airframe KNOWN to be lighter than the others. 1/4 scale is an odd size... a little heavy for glow (sometimes) and a little small for gas (sometimes) 50cc gas is awesome 3D in a 15-16 lb airplane in 1300-1400 sq in.

Then select a good balance powerplant of P:W.

Finally determine the $$$ items you can put on it to drop weight...

Do these 3 things and you'll have a more satisfying 3D aircraft.

Hope this helps...

J. David