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lets hammer this out for once..

OutcastZeroOne

Fly, yes... Land, no
#1
We have all heard the debate over if a plane is heavier it will fly better in windy conditions. I fail to understand this. If a plane is heavier then a lighter version it still has the same wing area, same drag, but now the motor must work to move more weight against stronger wind. How is a heavier plane sopossed to help this? Do birds fly with coconuts to help fly in windy conditions?

Simple challange. Make 2 identicle planes, but have one be heavier and fly them at the same time and see if there is a noticable differance in flight performance in windy conditions.

My best guess is this all started when someone put a bigger motor on a plane and was able to fly in wind better, not because of the plane being heavier, but because of it having more power.
 

Tritium

Amateur Extra Class K5TWM
#2
If the force of the wind is constant then it works more on a light than a heavy object. The heavier object reacts slower to impulses of a fixed level than a lighter object will to the same force. That is why a 30 pound kid is easier to push over than a 300 lb adult.:p Basic Physics! :) (If anyone try's the above example be sure to get video ;))

I used to fly Frisbie's a lot and the Heavy one was always preferred in a windy situation because it would take more wind to upset it's course.

Thurmond
 

OutcastZeroOne

Fly, yes... Land, no
#3
If the force of the wind is constant then it works more on a light than a heavy object. The heavier object reacts slower to impulses of a fixed level than a lighter object will to the same force. That is why a 30 pound kid is easier to push over than a 300 lb adult.:p Basic Physics! :) (If anyone try's the above example be sure to get video ;))

I used to fly Frisbie's a lot and the Heavy one was always preferred in a windy situation because it would take more wind to upset it's course.

Thurmond
But by the same definition it will be harder to turn, and react slower to a change of direction.

Most of my planes are UNDER 200grams flying weight. I fly them in 4-8mph winds with 15 mph gusts with no problems. I've even gone up in 20mph winds with out too much dificulty, and I rate my skill level as somewhere above novice. My planes weigh less then some peoples batteries, yet I still punch through the wind with little problem.
 

Ak Flyer

Fly the wings off
Mentor
#4
That is true of an equal sized plane that's encumbered with extra weight.

Take a plane and scale it up though and it's different. The extra weight makes it ly bettering wind reacting less to impulses yet with the bigger control surfaces it flies with the same precision. Try it. Fly a foam cub and fly a big balsa cub. The difference is incredible. Take an edge or extra or any other plane and the bigger ones fly better.
 

OutcastZeroOne

Fly, yes... Land, no
#5
That is true of an equal sized plane that's encumbered with extra weight.

Take a plane and scale it up though and it's different. The extra weight makes it ly bettering wind reacting less to impulses yet with the bigger control surfaces it flies with the same precision. Try it. Fly a foam cub and fly a big balsa cub. The difference is incredible. Take an edge or extra or any other plane and the bigger ones fly better.
Comparing balsa to foam, kind of unfair. some of that performance could be due to a differance in stiffness of the materials.

Also, simply compairing a larger plane to a smaller one dosent mean much. Take 2 motors, one phisically smaller than the other but with the same Kv rateing. The larger one will have more torque to keep spinning closer to the Kv rating with trying to sling a BIGGER prop than the smaller one.

This is a very simple thing to do. Just make two planes the same, but give one some dead weight to make it weigh more and then see if there is any differance between the two aircraft in windy conditions.

Im still waiting to see birds flying with dead weight in their claws to fly through wind better. Coconuts, bricks, rocks, etc.
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#6
OZO,

I think the critical dimension that's being missed here is drag.

Penetration is greatly affected by weight, as Thurmond pointed out, but you are also correct to counter that a light plane can still penetrate. For a light plane to perform as well in the wind to a heavier similar classed airframe, the wind will need to have less grab on the airframe -- meaning lower drag.

Think flaps. You drop your flaps, suddenly you loose penetration. Haven't lost an gram of mass, but the plane slows and is buffeted more by the wind.

In the case of thermaling, it's exactly what you want: flaps up, slice through the air with little loss or affect. flaps down, drag skyrockets (as well as lift, hopefully) and the plane can now by dragged upward by the uprising wind.

Birds are a side issue as much as material here. They can dynamically change their airframe from sleek to draggy as easy as we can take a step, and will do so with the pilot literally feeling the wind on the wingtips -- not something even a full scale pilot can do. smaller lighter airframes are performing much better with stabilization modules which weakly mimic what that bird brain is doing. comparing airframe-to-airframe and tossing in a stabilizer or dynamically changing one of the airframes, means we're no longer comparing airframe to airframe to understand why the wind is affecting us.

Now if you can convince two European swallows to carry a coconut, that I want to see.
 
#7
Try slope soaring. Same plane, no wind take all the balast out. Windy, add balast or you won't penetrate. Sure, it takes more energy BUT you have more energy.

If you limit the power then lighter will be faster, however it will also be more fidgety.

Really this is a noob question. If you've got several airplanes of the same type under your belt you'll see the difference. Shoot, 20-30 and it's not really worth answering. As a combat pilot I went through that many in a year easy. Heavier planes on windy days, lighter on no wind. It's better to be able to control your plane and fly then to not control your plane. this is one reason why the flite test planes don't work so good round here. I have to wait till almost dead calm "Kansas style wind" to fly here. If your idea of a windy day is 10-15 mph, you don't want to move here.
 
#9
It is the same reason competitive sailplanes have water ballast in their wings. They can use it to help penetrate if the conditions (thermals and ridges) offer good lift but if the weight isn't needed, like before landing/finish line, they'll dump it.

 

pgerts

Old age member
Mentor
#10
One hot potato?
Like asking it Futaba is better than Hitec better than Spektrum......

I agree with OutcastZeroOne. I want light planes and i am one of the few flying in almost every weather.
It is the speed and profile that is most important when it is windy in my opinion.

A heavy plane is a lot better on the ground when windy. It is impossible to taxi a light plane in wind (other than into).

There is of course a different case if you are on the slope when it is storm. A loaded glider is much faster than a plane that you have to dive in 30 degrees down all the time when flying. (but it shurely looks fun)
 

Ak Flyer

Fly the wings off
Mentor
#11
Comparing balsa to foam, kind of unfair. some of that performance could be due to a differance in stiffness of the materials.

Also, simply compairing a larger plane to a smaller one dosent mean much. Take 2 motors, one phisically smaller than the other but with the same Kv rateing. The larger one will have more torque to keep spinning closer to the Kv rating with trying to sling a BIGGER prop than the smaller one.

This is a very simple thing to do. Just make two planes the same, but give one some dead weight to make it weigh more and then see if there is any differance between the two aircraft in windy conditions.

Im still waiting to see birds flying with dead weight in their claws to fly through wind better. Coconuts, bricks, rocks, etc.
I think you missed the point I was making. I'm not going to argue this one, but I will say that I'm agreeing with you partly. A heavier plane of the same size will suffer in performance, yet be more stable in flight. A lighter plane will be more agile but will be moved around much more by every little change in the air. If you compare bigger heavier planes to smaller foam planes, they fly better. I'm also comparing smaller aerobatic planes to bigger aerobatic planes, to huge aerobatic planes. I have a friend who has a small yak with an electric motor, a big yak with a 50cc gas motor and a huge yak with a 100cc gas engine. He likes yaks. They are all extremely good performers and he's a great 3d pilot. He flies the huge 100cc yak in competition because its the smoothest and easiest to hold lines in windy conditions. They will all perform the same maneuvers just as easily but the bigger heavier model holds its lines better. The little ones get blown around more. Ask any large scale pilots how they like big planes in wind.

Bigger flies better, period. That's been my experience and ill stick to it.

Heavier isn't good, it's just a sie benefit that they are more resistant to wind. If you have a huge light plane it's going to get blown around too. A good outdoor windy day plane is going to have a higher wing loading than an indoor slow plane. I love 3d planes and I have an indoor plane that's great for flying slow and low and inside a gym. It can't handle windy days at all. I have a plane almost the exact same size that's much heavier and it is a serious handful to fly it inside because its weight requires more speed but it's my absolute favorite plane to take outside on windy days. I actually prefer to fly it in strong winds. It's weight is a hindrances one arena and a great benefit in another.
 

Ak Flyer

Fly the wings off
Mentor
#13
This is a very simple thing to do. Just make two planes the same, but give one some dead weight to make it weigh more and then see if there is any differance between the two aircraft in windy conditions.
Or you could fly your plane in the wind, then add weight to it and fly it again and tell us your results. Don't really need two planes do you?
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#15
Not to beat a dead horse . . . oh, it's dead and I'm enjoying beating it!

While it doesn't speak good or bad about the premise, I think the original test suggested is a bit flawed. It starts with a craft tuned to fly light weight and in high winds, then the test is to add weight to a tuned craft. It's been optimized to fly in that environment, of course it will fly degraded. If you had a way to magically reduce the weight of that craft, I think you'd see a similar drop in performance (in different parameters, though -- penetration being one).

I would completely agree, it doesn't have to be heavy to slice through the air -- arrows do that all the time -- but all things being equal and being in the middle of your flying envelope, a bit more weight dampens the wind's effects while a bit less improves performance in calmer air. Going away from the optimized peak of ANY individual airframe's envelope, will result in a performance drop in one way or another.
 
#18
I pretty much failed physics, so I have no idea what I'm talking about here, but in my early slope days, I was always told to add ballast on the windy days. They said it gave more "penetration" but the way I understood it, the wind resistance and potential speed was the same, it was just that the extra up draft allowed us to carry some more weight and give a lot more stability in the rough conditions. I'd love to hear the actual explanation on what the extra penetration into the wind meant.
 
#19
Its a terminal velocity thing. Terminal velocity is the speed you can achieve in free fall where your drag equals the force available by your mass. On the moon everything has the same terminal velocity. In the Atmosphere a feather flits while a hammer falls directly.

On the slope, if your planes Terminal Velocity unballasted is 20 mph and the wind speed is 30, you go backwards 10 mph. Ballasted and now your TV is 45, you go forward. You also can't turn as tight. You put more stress on the wings and it takes more effort to do everything because you have to move more mass around. Nice thing is, if you're plane is built right, it'll take the force and we have servos and batteries doing the work.

If instead you had a box on the floor and you wanted to move it AND it was empty, you could slide it quite easily. Add weight to the box and it becomes less easy. If you have an empty box and there is a strong wind, the box might blow around a bit. With weight the box gets the same forces as when it was empty BUT it just sits there un affected. It's easier to move an empty box, better one might say. If its too light however, it'll just get pushed all over the place by the wind.
 

pgerts

Old age member
Mentor
#20
This seems extremely hard to HAMMER out ;-)
Comparing motor models with slope gliders (please forgive me stealing the RCM&E august article) does not give so much as you will normally want to fly your motor planes when it is calm or low winds - BUT you want to get high winds when flying on the slope.
I do not think that theories of empty boxes does anything to planes.
I often hear that gyros help in winds and that Heavy planes are better.
I will always ask the "vice men" to show - but they never do for reasons i do not know ;-)
Speed is of importance when flying in high winds. Low weight helps my planes flying comfortable with the wind and the motor helps against the wind. The plane does not care anything for ground speed - only the speed against the wind.
I say that a heavy plane is harder to fly than a light plane - regardless if it is windy or not.