longer & slower flight

[realtimerecon]

Were talking about (2) exact same planes w/ same power output .Plane #1 weighs 5 ozs.less than plane #2.........Plane #2 has 12" more wingspan than plane #1.......Which one will give the longer & slower flight ? RTR

[JetPlaneFlyer]

Were talking about (2) exact same planes w/ same power output .Plane #1 weighs 5 ozs.less than plane #2.........Plane #2 has 12" more wingspan than plane #1.......Which one will give the longer & slower flight ? RTR

Generally the plane with the lowest wing loading will be capable of flying slowest but it's impossible to say if that would be #1 or #2 because you dont give enough info.

[realtimerecon]

Generally the plane with the lowest wing loading will be capable of flying slowest but it's impossible to say if that would be #1 or #2 because you dont give enough info.
That would be plane # 2 then. But w/ increased wingspan also comes xtra Wt.ABOVE the 5 ozs. :confused:

[JetPlaneFlyer]

If #2 has the lowest wing loading (i.e. weight divided by wing area) then it will have the slowest minimum flying speed.. Also if it has longer wings (and the same chord) it must have a higher aspect ratio so will have less induced drag than model #1 and will make more efficient use of it's power... However it's hard to say if this would make up for the increased weight and give better duration (ie. longer flight)



Steve

[realtimerecon]

It seems like a catch 22 thing.Increasing the wing gives more lift(less power to stay in the air) ,but increases Wt. & drag.

[nmasters]

Both wing loading and span loading affect flight performance. As JP said the one with the lower wing loading will probably have the lowest minimum speed. However the sinking speed is proportional to weight/span^2 so both planes have an advantage in one respect or another. This web page explains them: http://chuckglider.blogspot.com/2007/09/get-load-of-this-what-are-wing-loading.html


I'll probably get into trouble for even mentioning this because I've been told that it has no theoretical basses but you could compare the volume loading: http://www.ef-uk.net/data/wcl.htm
The one with the lowest number will probably have the best combination of wing loading and span loading for long duration slow flight

--Norm

[realtimerecon]

OK,........so then -as a general rule of thumb- is it better to have more wingspan.OR to be lighter ?

[nmasters]

LOL it ain't an either/or thing. Decreasing the weight also decreases the span loading and so dose increasing the span.

[HerkS]

None of it means anything unless you state more about the plane's intended purpose.

It is the mission that first defines the configuration.

Also 12 inches more span on how much of a wing???? And five ounces on how much weight???

As "Multivac" once said: "insufficient data to provide a meaningful answer."

[realtimerecon]

Aerial photography,as sloooooooooooow as possible.And ya i know that's what the throttle is 4...RTR

[mnowell129]

RTR,
I think what is being gently being suggested is we need to know more details about the planes. An increase of 5 ounces on a 12 pound plane isn't as significant as 5 ounce on a 10 ounce plane.
What weight planes are you talking about?
What wingspan?
What wing area?

[realtimerecon]

RTR,
I think what is being gently being suggested is we need to know more details about the planes. An increase of 5 ounces on a 12 pound plane isn't as significant as 5 ounce on a 10 ounce plane.
What weight planes are you talking about?
What wingspan?
What wing area?
This plane. http://www.hobbyzone.com/rc_planes_hobbyzone_super_cub.htm

[DLC]

You also have to consider the airfoil characteristics. An airfoil with a high max lift coefficient (e.g. an undercambered airfoil) will, all else being equal, let the plane fly slower than an airfoil with a low max. lift coefficient (e.g. a symmetrical airfoil). I got experimental verification a while back that this is true even at the low RN's that models typically experience when flying with a friend. He flew a GWS Cub which has a very undercambered airfoil. I flew a plane with similar configuration and size and essentially the same wing loading but with a semi-symmetrical airfoil. His Cub would cruise markedly slower than my plane.

[JetPlaneFlyer]

This plane. http://www.hobbyzone.com/rc_planes_hobbyzone_super_cub.htm
Well if the real question is "is it worth grafting on an extra 12" of wingspan onto the Hobbyzone Cub".... The answer is "probably not".. Although (using your figures of a 5oz weight increase) the wing loading would be reduced slightly it could upset the handling of the model and the extra weight could leave it marginally powered and sluggish in the climb. I'd just leave it as it is.

A better option to improve overall performance and reduce minimum flying speed might be to substitute lighter lipo batteries for the supplied NiMh items? Or just find a model with a slightly higher spec?

Steve

[lincoln]

My back of the envelope calculations suggest that the longer wing would pay off, at least by a few percent. The power for level flight would be slightly reduced. If the power is marginal to start with, climb would be improved, but if it isn't, climb may be worse. However, if the tail isn't big enough to handle the bigger wing, forget it.

For relatively low aspect ratios, taking advantage of an undercambered airfoil isn't really taking advantage. Especially if the aircraft is relatively "clean". However, I think this one's wing may be just long enough, and the rest of the aircraft draggy enough, that a liftier wing might help.

Of course lighter weight is best. And I doubt that a foot more wing has to cost 5 ounces.