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Old Jan 31, 2009, 05:22 PM
the guy
Joined Mar 2007
192 Posts
Discussion
How much load can rc planes take?

Hi,

I've never known how much load can you put on some rc planes, no one has ever really said anything about it, just gone out and done it. I mean say, a f3a 32" ws 560g cap 232 aerobatic model could haul how much weight. I'm looking to do lots of things with my planes, fpv, retracts, balloon drops all that fun stuff but I don't know how much weight I can put on some planes. Obviously I can test it but I've been searching for a plane that can specifically take a good amount of weight. How much could a Graupner Wilga 2000 41" ws take? Its a high wing beginner type plane but has some power. Is there a way of predicting how much weight a plane can take through specifications only?


Sorry this is quite abrupt, thanks
Edd
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Old Feb 01, 2009, 06:11 AM
the guy
Joined Mar 2007
192 Posts
anyone?
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Old Feb 01, 2009, 07:13 AM
An itch?. Scratch build.
eflightray's Avatar
South Wales U.K.
Joined Mar 2003
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There are 'heavy lift competitions' for model aircraft where the load carried runs to many pounds. But they are designed to those loads.

I don't think there is a calculation for the max load a model can carry, there are so many variables, (that said someone is sure to come up with an on line calculator).

The limit for a conventional RTF foamie is likely to be the wing strength before it just folds. Also what type of maneuvers are required will also control the safe weight to be carried.

Quite a few of the Aerial Photography forum models are carrying quite heavy cameras, but again they are designed for the job and are unlikely to do loops etc, (intentionally ), that could stress the wings and put the camera at risk.

For most conventional models, the only thing is to try extra weight a little at a time, (obviously mounted on the CG, or distributed to maintain the CG).

For extra heavy loads, then wing strengthening is needed and more motor power as well.

Sorry, but I don't think there is a - 'if it's this big, it can carry this much load', sort of calculation.

It's down to trial and error, though just one 'error' can mean building/buying another model, but a stronger one.
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Old Feb 28, 2009, 09:42 AM
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Atlanta, GA
Joined Dec 2007
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Telemasters are great for carrying a payload. We've got a Senior Telemaster that we got a bigger motor and battery for (Picked using the Axi Motor Selector Tool), and we're currently flying almost 3 lbs worth of computer, cameras, and sensors on board. And that's not counting the extra weight of the bigger battery and motor. Telemasters and similar trainer-type aircraft are commonly used by AUVSI competition entries because, straight out of the box with a scaled up motor/prop/battery, you can safely add several lbs worth of weight.





Axi motor selector tool is here:
http://www.modelmotors.cz/axisetuphobby-lobby/
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Old Feb 28, 2009, 09:56 AM
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Atlanta, GA
Joined Dec 2007
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P.S. If you've got money to spare, buy an extra wing for your airplane, and do a "static wing loading test" until it breaks. That is, distribute weight evenly across the wing until it can't take it any more. If you're just planning on flying straight and level with mild turns, you need to be able to take maybe 2G's - your wing should be able to stand up to 2x the weight of your plane. If you want to fly aerobatics, you need more like 3-5G's.

The only other factor is motor power. For that you can use the axi motor selector tool, or Electricalc, or motocalc.
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Old Aug 06, 2009, 01:18 PM
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Joined May 2008
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No I think model airplanes goes threw a lot more G than 2 and 3-5. From what i heard you could almost kill a man with the amount of G a model airplane goes threw. But most of my planes are gas and they are probably more capable than most foamy.

The Spare wing test thing is a waste Because right after you find out something you already knew you are going put you bomb drop or what ever and then try to fly it and it will crash and you will kick you self for busting that other brand new wing that you now need.

I think you should go with a Tele-master or...... this next one is great A Butterfly 99' powered glider.
I have a unfinished on laying around and let me tell you it is huge for its wing load. I have heard that some people have loaded it op with 5 LB but you need to reinforce the wing.

If you want i could take pictures of my butterfly. Like of the cargo bay
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Old Aug 15, 2009, 01:30 AM
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Southern California
Joined Jul 2009
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Trial and error is probably the best way to go,

but for estimating:
only for steady level flight
you should be able to set gross weight equal to the lift force

Lift force = Gross Weight = (0.5)ρV2CLS

air density - ρ = .002377 slugs/ft3
depends on airfoil (?), usually CL ~ .8 1.0
V = Velocity
S = Wing Area
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Old Aug 15, 2009, 04:17 PM
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What a model "can" lift is also a different matter to what mass a model can lift and still retain anything like decent flying manners.

That will, of course, depend on the design. As an example, a constant chord wing, with a thick section is a lot more forgiving of high wing loading than a thinner, highly tapered wing, even though both may have the same area and the same "lift force" as in the equation above.

Remember, that with the equation above, this is the maximum weight in level flight. You've got to be able to get the model off the ground somehow, and as mass increases, so does take off distance, and stall speed. You may have a model which is technically capable of supporting a mass of X in level flight, but the stall speed may be only a fraction below that level flight speed, so any attempt to climb/turn may be a disaster, especially if ANY G is pulled, as 1.5G increases wing loading by 1.5x, and stall speed may actually be higher than the level flight speed of the model.
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Old Oct 12, 2012, 07:15 PM
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Joined Apr 2011
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The Old Thread, but still have the same problem.

I do have the similiar problem. The wing can hold the weight. But unfortunately, the engine/prop (im not sure yet) is not powerful enough. This weight problem makes my plane very difficult to fly to higher level. (like the level when my plane has no equipment attached)

For example, the plane will be able to achive 100m in a few second, if she doesnt carry the equipment. But the plane will only able to go 50m in a longer time when the euipment attached to her.

How to resolve this kind of problem.

Thanks before
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Old Oct 20, 2012, 08:07 PM
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My Queen Bee is capable of carrying several pounds of batts, camera gear or whatever...
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Old Nov 06, 2012, 01:00 AM
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United States, MD, Annapolis
Joined Jan 2008
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Sounds like you are power limited. A different prop might help but more likely you need a bigger motor. Using a bigger wing or flaps might buy you a bit more lift but from your description, it's more likely power would pay bigger dividends.

Regards,
John
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Old Nov 06, 2012, 08:14 AM
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+1

CC~ What airframe and power system are you using? How much payload are you carrying?
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