Is there a table that shown engine size vs. weight of the model? i.e. the maximum weight of the model a specific engine size can handle.

Thank you.

While there probably is a table out there the real issue is, how does the pilot intend to fly the model? For example. I have a Sig Kadet Seniorita that calls for a .15-.25. I will be outfitting it with a .20 and teaching my kids to fly. Joe might want to make it a float plane so he puts a .32 SX or a .40 on it to handle the extra weight and drag. Then Bill Hemphil says I can hover that thing and puts a .50sx on it.

It depends...Does the real plane fly on the prop or on the wing? There are too many variables here to have an intelligent discussion on this without more information.

Bill, AMA 4720
WACO Brotherhood #1

I agree with you, but each engine should have been designed with certain power to lift particular weight; right?

From my experience:

.049 try to stay under 16 ounces
.15 try for around 28 ounces becomes a dog if more than 35 ounces
.46 a dog at six pounds, unlimited verticle at 4.5 pounds.
.60 7 to 10 pounds

The opinions of others may vary.

The plans/Manufacturers manuals have recommendations for engine sizes to go with the models. If you're trying to design a plane, its a whoe new game. To determine deterimine if a plane will fly, you need to look at wing loading and drag. A low wing loaded plane will be easier to keep aloft with less engine (sail planes typically fall into the 5-7 oz/sq-foot range). A higher wing loading, lower drag configuration, as seen in many sport planes (15-20 oz/sq foot) will need more speed. Planes with even higher wing loading (20-24 oz/sq foot) need even more. Planes will fly with thrust/weight ratios less than 1, as long as the engine has sufficient power to overcome the drag on the wing at the required velocity to create sufficient lift.

Thrust/weight ratio is what determines vertical performance. If you want the plane to hover, you need a thrust/weight ratio greater than 1. You can get a rough estimate of the approximate thrust by using a calculator such as Thrust HP and use the Manufacturers rated horsepower (estimate about 75% of what the mfg claims). Look at different prop combinations, adjust RPMs to approximate power, and you'll get an estimate of thrust.

Brad

Too many variables. Wing chord and thickness, surface area, wing loading, drag, etc. Then there's performance. A Tiger Moth will fly right with a .61 while a similar size and weight Ultimate biplane would need a 1.20 to meet the designed flight envelope. We lately tend to over power our models compared to 25 years ago. No one expected an airplane to torque roll or fly rolling harriers or have "unlimited vertical".

Some models fly on the wing and others on the prop. The thrust needed to actually lift off and fly is much lower than what is needed to hover or accelerate vertically. Most "peppy" sport models can take off and loop at 1/4 throttle, so the power needed depends on the type of flying you intend to attempt.