Wing Loading
02-03-2011, 10:01 AM
#26
RE: Wing Loading
I'll try once more to prove that wing loading is the key to sucess. When I flew and fabricated aerial targets for the Unites States military we were tasked by the Army to provide a target to be used for aerial tracking and targeting. This target was to be used to redesign the computer software in the Apache helicopter fire control system. The target would have the same dimensions of a full scale Cessna 150 in 1/2 scale. I suggested that we copy the airfoils of the Golberg Falcom 56 and design it as a taildragger. We built the prototype using conventional carpentry methods using aircraft grade plywood and Stika spruce for all the stringers. It was powered by a Kawaski snowmobile engine. The plane weighed 110 lbs dry and 140 lbs wet. We test flew it off our dry lake sight and it proved to be a winner or so we thought. We took it to White Sands were the test were to be conducted. Upon arrival we were escorted to our airfield which turned out to be a unimproved dirt road. We had about 150 ft of useable road and all three of our targets crashed on takeoff. The reason came back to wing loading. The army was not pleased but they agreed to build us a useable runway. We ended up with a strip 800X100 ft in dimensions. Since we were working directly with Army aviation units they understood the wing loading dilema and asked if we could construct an airframe half the weight. Naturally we said yes and provided them with an airframe constucted totally from composite materials. Using this mean of construction we could now takeoff in less than 150 ft but the cost per airframe quaddroupled and the Army could not justify this increase.
02-03-2011, 11:00 AM
#27
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RE: Wing Loading
Hi,the P51 I showed in the landing thread flies a lot better when I added 5 Lps o led to it..It was a little bit "flimsy" when i tried it first without adding this weight..
The Sist FW190 is a very heavy bird to but has no trouble carrying its weight,roughly 25 Lbs..
As far as I can tell(i´m no pro though),smaller aircrafts are a lot more sensitive to high wingloadings than larger ones..
//Bokis
The Sist FW190 is a very heavy bird to but has no trouble carrying its weight,roughly 25 Lbs..
As far as I can tell(i´m no pro though),smaller aircrafts are a lot more sensitive to high wingloadings than larger ones..
//Bokis
02-03-2011, 11:28 AM
#28
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RE: Wing Loading
I'll try once more to prove that wing loading is the key to sucess. When I flew and fabricated aerial targets for the Unites States military we were tasked by the Army to provide a target to be used for aerial tracking and targeting. This target was to be used to redesign the computer software in the Apache helicopter fire control system. The target would have the same dimensions of a full scale Cessna 150 in 1/2 scale. I suggested that we copy the airfoils of the Golberg Falcom 56 and design it as a taildragger. We built the prototype using conventional carpentry methods using aircraft grade plywood and Stika spruce for all the stringers. It was powered by a Kawaski snowmobile engine. The plane weighed 110 lbs dry and 140 lbs wet. We test flew it off our dry lake sight and it proved to be a winner or so we thought. We took it to White Sands were the test were to be conducted. Upon arrival we were escorted to our airfield which turned out to be a unimproved dirt road. We had about 150 ft of useable road and all three of our targets crashed on takeoff. The reason came back to wing loading. The army was not pleased but they agreed to build us a useable runway. We ended up with a strip 800X100 ft in dimensions. Since we were working directly with Army aviation units they understood the wing loading dilema and asked if we could construct an airframe half the weight. Naturally we said yes and provided them with an airframe constucted totally from composite materials. Using this mean of construction we could now takeoff in less than 150 ft but the cost per airframe quaddroupled and the Army could not justify this increase.
Read more: http://www.rcuniverse.com/forum/m_10...#ixzz1CvQ8TnQQ
Read more: http://www.rcuniverse.com/forum/m_10...#ixzz1CvQ8TnQQ
That is what flaps are for anyway.
02-03-2011, 11:31 AM
#29
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RE: Wing Loading
quote:
ORIGINAL: dvs1
First why are you comparing warbirds to gliders. Unpowered flight vs powered flight and wing loading are two completely different fields. Of coarse you would want light wing loading with a glider for longer flight/ soaring times. With a large warbird it is in a way irrelevant to me, as a higher loaded wing actually flys better, it is more stable in the air, is less affected by turbulent air pockets, and also handles crosswinds better. Back to landing speeds, irrelevant as well. I have had 2 Top Flite ARF 84'' Mustangs for comparison, one just to get the feel for warbirds years ago, very light, no heavy retracts or extra gear, the more recent, fully fiberglassed, heavy retracts, extra gear, scale acceseries, ect, ect, difference in weight 6 lbs. As far as landing I really did not notice much of a difference, however flight characteristics and ease of flight was far better with the heavier plane.
If you want to lean the bird down to each their own. to me, fact of the matter is that this is a warbird discussion forum and when it comes to warbirds lighter does not necessarily mean better.
Im not about to start throwing lead bars in my planes but I don't really worry about cutting corners or altering plans to cut the weight down either. I have never had any plane to date that I really thought to myself I wish I could land slower in fact the opposite. I like realistic flight, and it actually bothers me when flying my sport planes that some of them the plane has to be almost crawling before it will stall out and get on the ground. I don't like it when I am idling a plane 10 ft from the ground, make my final turn, and fly some 500 ft. to the runway and still need to slow more before the plane will be flying slow enough to flare to land.
I can't say this any better, so I won't try. You and I are perfectly parallel in our thinking on this.
I will add this additional point, and it about building. It is so nice to be able to build, and not agonies over ounces, then pounds, so you can hold a vertical line at will. Weight is just not my primary concern when building a scale war bird. Let me qualify that. I do think about it in the tail, for 1 once back there will cost you 4 in the nose, but overall, scale detail, strength, and life of service are way more important things to build into my war birds, and this makes building much more fun for me. That is just me. Not everyone's cup of tea, but those who haven't tried a scaled out war bird, might just find that this type of building does have a lot to offer.
We don't really 'set out to add weight', it just works out that way, and you don't worry about it. Till you build in strength, add scale detail (including the gear and supporting structures), install all the metal gear servos to work all the options (I even use JR 8611 servos on the tail wheels), and redundancy in batteries to power everything, it is what it is.
Read more: http://www.rcuniverse.com/forum/m_10...#ixzz1CvTY64m9
ORIGINAL: dvs1
First why are you comparing warbirds to gliders. Unpowered flight vs powered flight and wing loading are two completely different fields. Of coarse you would want light wing loading with a glider for longer flight/ soaring times. With a large warbird it is in a way irrelevant to me, as a higher loaded wing actually flys better, it is more stable in the air, is less affected by turbulent air pockets, and also handles crosswinds better. Back to landing speeds, irrelevant as well. I have had 2 Top Flite ARF 84'' Mustangs for comparison, one just to get the feel for warbirds years ago, very light, no heavy retracts or extra gear, the more recent, fully fiberglassed, heavy retracts, extra gear, scale acceseries, ect, ect, difference in weight 6 lbs. As far as landing I really did not notice much of a difference, however flight characteristics and ease of flight was far better with the heavier plane.
If you want to lean the bird down to each their own. to me, fact of the matter is that this is a warbird discussion forum and when it comes to warbirds lighter does not necessarily mean better.
Im not about to start throwing lead bars in my planes but I don't really worry about cutting corners or altering plans to cut the weight down either. I have never had any plane to date that I really thought to myself I wish I could land slower in fact the opposite. I like realistic flight, and it actually bothers me when flying my sport planes that some of them the plane has to be almost crawling before it will stall out and get on the ground. I don't like it when I am idling a plane 10 ft from the ground, make my final turn, and fly some 500 ft. to the runway and still need to slow more before the plane will be flying slow enough to flare to land.
I can't say this any better, so I won't try. You and I are perfectly parallel in our thinking on this.
I will add this additional point, and it about building. It is so nice to be able to build, and not agonies over ounces, then pounds, so you can hold a vertical line at will. Weight is just not my primary concern when building a scale war bird. Let me qualify that. I do think about it in the tail, for 1 once back there will cost you 4 in the nose, but overall, scale detail, strength, and life of service are way more important things to build into my war birds, and this makes building much more fun for me. That is just me. Not everyone's cup of tea, but those who haven't tried a scaled out war bird, might just find that this type of building does have a lot to offer.
We don't really 'set out to add weight', it just works out that way, and you don't worry about it. Till you build in strength, add scale detail (including the gear and supporting structures), install all the metal gear servos to work all the options (I even use JR 8611 servos on the tail wheels), and redundancy in batteries to power everything, it is what it is.
Read more: http://www.rcuniverse.com/forum/m_10...#ixzz1CvTY64m9
There is just two totally different views here and neither side aggrees with the other.
02-03-2011, 01:06 PM
#30
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RE: Wing Loading
thanks...
and becouse there is a billion inches of snow on the ground, I'm gonna test some wing loading...
IL2 style.. man I love IL2.
and becouse there is a billion inches of snow on the ground, I'm gonna test some wing loading...
IL2 style.. man I love IL2.
02-03-2011, 05:30 PM
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RE: Wing Loading
Usually scale aircrafts are heavier due to airframe structures and scale operational equipments onboard... Try to increase camber on landing by increasing flaps... Also raise angle of attack depending on your airfloil, flaps would make your AoA a little lower but gives you a lot of lift and drag... And use throttle to control rate of descend.
02-03-2011, 05:53 PM
#32
RE: Wing Loading
ORIGINAL: GerKonig
Interesting discussion, but if this ''theory'' would hold true, everybody would be adding weight to their warplanes. So, how many pouds of lead did you add to make your model fly better 10 pounds, 20? A 82'' model with 55 poulds will fly really nice? The Space Shuttle looks pretty solid on the landing pattern...
Again, very interesting discussion...
Gerry
Interesting discussion, but if this ''theory'' would hold true, everybody would be adding weight to their warplanes. So, how many pouds of lead did you add to make your model fly better 10 pounds, 20? A 82'' model with 55 poulds will fly really nice? The Space Shuttle looks pretty solid on the landing pattern...
Again, very interesting discussion...
Gerry
Kyosho 56" ws BF-109. Mfgr suggests 4.5-5.6 lbs all-up wieght. I assembled this one and flew it right out of the box with no extras at 6.5 lbs on a Saito .62 4c. Decided later to add struts, flaps, radiators, new paint job and other details and came up with 11.25 lbs on the same motor. (Almost 2 lbs more weight in the nose as penalty for stuff done at the tail and a larger battery pack)
The plane was squirrely and unpredictable in marginal winds and tracked like a drunken sailor at 6.5 lbs. It was quite prone to ballooning on the landing flair as well, more so even than my J3 Cub.
After the kit bash, and the near doubling of weight, it flies like it's on rails and heavy cross wind landings are a pleasure. "Feels" like a comfortable landing speed as well...not like I have to "rocket" the approach.
I have found that adding a bit of "ballast" has helped the flight characteristics of most of my planes. In fact the 40 size GP Cub flewso much better with the floats that I made up a 2.75 slug of lead and a mount for it right at the CG for when I'm flying it with the wheels on.
Here's the slug next to a 4" wheel for reference and a bad video complete with a botched landing of the 109. but it does show that the approach speed is actually pretty slow with a 7 mph direct X-wind.
http://www.youtube.com/watch?v=74oRv...eature=channel
P.S. The guy who shot this vid is also named Lee. All other references to "Lee" in his other vids refer to him, not me!
02-04-2011, 04:24 AM
#34
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RE: Wing Loading
Hey guys
Since I am a flyer of 1:1 scale aircraft I will try to analyse with simple words what is happening so all of the guys who are missing some points will be able to understand a broad subject like this.
The flight of a wing configuration is affected by a whole set of different parameters. One of them is the wing loading. Some other are Reynolds, static weight, centre of pressure (dynamic weight), angle of incidence, angle of attack, wing type, airfoil type etc. Different airfoils are giving different results the same happens with different wing types. Some of them are high lift; some others are more penetrating so they are faster. There is always the compromise of lift in order to give it back for speed. So either we have wings that in their envelope fly faster; or they create greater lift in compromise with speed. Both situations give to our airplane energy to fly. As pilots
we must understand that in subsonic flights we have to weight first of all our wings in a correct manner (to keep the dynamic center of pressure always in balance with the static point of pressure. The angle of incidence is another factor that affects flight. It must be always according to the envelope. The high lift devices (flaps, slats etc) are increasing the lift. So they give the wing the ability to fly in lower speeds. In order not to be tiring, I will go dirrectly to the point that is:
Wing loading by itself is one of the points that affect the flight if it is not with accordance with the envelope. To be more specific it will prove us the flaws of our building experteese and specific our lack of picking the right airfoil, or wing type, reynolds, or missing flaps, slats etc.
You see judging by using one of the criteria of flight which is wing loading our result will be incorrect. Otherwise the 1:1 Boeing 747 would not fly right because it has a bigger wing loading than a Cessna 150 Skycatcher.......
These are my 2 cents.
Since I am a flyer of 1:1 scale aircraft I will try to analyse with simple words what is happening so all of the guys who are missing some points will be able to understand a broad subject like this.
The flight of a wing configuration is affected by a whole set of different parameters. One of them is the wing loading. Some other are Reynolds, static weight, centre of pressure (dynamic weight), angle of incidence, angle of attack, wing type, airfoil type etc. Different airfoils are giving different results the same happens with different wing types. Some of them are high lift; some others are more penetrating so they are faster. There is always the compromise of lift in order to give it back for speed. So either we have wings that in their envelope fly faster; or they create greater lift in compromise with speed. Both situations give to our airplane energy to fly. As pilots
we must understand that in subsonic flights we have to weight first of all our wings in a correct manner (to keep the dynamic center of pressure always in balance with the static point of pressure. The angle of incidence is another factor that affects flight. It must be always according to the envelope. The high lift devices (flaps, slats etc) are increasing the lift. So they give the wing the ability to fly in lower speeds. In order not to be tiring, I will go dirrectly to the point that is:
Wing loading by itself is one of the points that affect the flight if it is not with accordance with the envelope. To be more specific it will prove us the flaws of our building experteese and specific our lack of picking the right airfoil, or wing type, reynolds, or missing flaps, slats etc.
You see judging by using one of the criteria of flight which is wing loading our result will be incorrect. Otherwise the 1:1 Boeing 747 would not fly right because it has a bigger wing loading than a Cessna 150 Skycatcher.......
These are my 2 cents.
02-04-2011, 06:33 AM
#35
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RE: Wing Loading
well an F4 has a glide slope of a brick. engines make that thing fly. the wings are there purley
for stabillity & directional control. they produce very low lift. & speaking of bricks, put a big enough
engine on a brick and it'll fly too. so in this case anyways, its not about the wings.
for stabillity & directional control. they produce very low lift. & speaking of bricks, put a big enough
engine on a brick and it'll fly too. so in this case anyways, its not about the wings.
02-04-2011, 07:30 AM
#36
RE: Wing Loading
ORIGINAL: Experten109/40
well an F4 has a glide slope of a brick. engines make that thing fly. the wings are there purley
for stabillity & directional control. they produce very low lift. & speaking of bricks, put a big enough
engine on a brick and it'll fly too. so in this case anyways, its not about the wings.
well an F4 has a glide slope of a brick. engines make that thing fly. the wings are there purley
for stabillity & directional control. they produce very low lift. & speaking of bricks, put a big enough
engine on a brick and it'll fly too. so in this case anyways, its not about the wings.
with the addition of the flaps and slats.
02-04-2011, 10:27 AM
#39
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RE: Wing Loading
ORIGINAL: Experten109/40
well an F4 has a glide slope of a brick. engines make that thing fly. the wings are there purley
for stabillity & directional control. they produce very low lift. & speaking of bricks, put a big enough
engine on a brick and it'll fly too. so in this case anyways, its not about the wings.
well an F4 has a glide slope of a brick. engines make that thing fly. the wings are there purley
for stabillity & directional control. they produce very low lift. & speaking of bricks, put a big enough
engine on a brick and it'll fly too. so in this case anyways, its not about the wings.
02-04-2011, 11:08 AM
#40
RE: Wing Loading
ORIGINAL: Experten109/40
well look at windtunnel tests, mostly every plane, car, truch, train, boat, building, etc that they put in
there is a much scaled down version of whatever there testing. even today with computer sims
they still use the windtunnel. there not to concerned about air molicule sizes, and it produces
accurate results.
well look at windtunnel tests, mostly every plane, car, truch, train, boat, building, etc that they put in
there is a much scaled down version of whatever there testing. even today with computer sims
they still use the windtunnel. there not to concerned about air molicule sizes, and it produces
accurate results.
I'm no areonuatical engineer though.. I just play one on the internet
Tom a real aero engineer.
02-04-2011, 11:12 AM
#41
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RE: Wing Loading
yeppers. and a pencil & paper, & grade school math, one can factor in the reynolds equation
and compensate. however I'm convinced is you scale down a warbird along with scale weight
the reynolds factor will be less of an concern. notice I said less lol
and compensate. however I'm convinced is you scale down a warbird along with scale weight
the reynolds factor will be less of an concern. notice I said less lol
02-04-2011, 12:24 PM
#42
RE: Wing Loading
ORIGINAL: MajorTomski
Me thinks ye should looketh more into the magic of the tunnel. Someone previous mentioned Reynolds number, that IS the factoring in of the differences in air molecule size and scale behavior. That is why THEY'RE accurate.
And not a very good one at that.
Tom a real aero engineer.
ORIGINAL: Experten109/40
well look at windtunnel tests, mostly every plane, car, truch, train, boat, building, etc that they put in
there is a much scaled down version of whatever there testing. even today with computer sims
they still use the windtunnel. there not to concerned about air molicule sizes, and it produces
accurate results.
well look at windtunnel tests, mostly every plane, car, truch, train, boat, building, etc that they put in
there is a much scaled down version of whatever there testing. even today with computer sims
they still use the windtunnel. there not to concerned about air molicule sizes, and it produces
accurate results.
I'm no areonuatical engineer though.. I just play one on the internet
Tom a real aero engineer.
I can build houses from the ground up, do design and some engineering in that field, am an expert at interior trim and wood work, including bending handrail and curved staircases, are you? So what. I have just as much admiration and respect for the modeler who can fly (and or build) circles around me, but sits behind a desk selling cars all day.
Let us share what we know in the spirit of mutual respect.
I'll now step down off the soap box.
02-04-2011, 01:26 PM
#43
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RE: Wing Loading
hey no worries Gary. I took physics too. its not too hard to figure out the true intentions
of employing the fabled " reynolds" theorium. lol. D
of employing the fabled " reynolds" theorium. lol. D
02-04-2011, 02:45 PM
#45
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RE: Wing Loading
Johnnie Red - Good interesting information, I saw you mentioned center of pressure. Do you know how to get that? Anybody knows that equation? If I move the CG close to that point, I know I would have lesser elevator force that contribute to the wing loading and stall speed but I'm worried about the plane's stability. Do you have info to what limit distance of CG with respect to that point?
02-04-2011, 08:42 PM
#48
RE: Wing Loading
ORIGINAL: Experten109/40
yeppers. and a pencil & paper, & grade school math, one can factor in the reynolds equation
and compensate. however I'm convinced is you scale down a warbird along with scale weight
the reynolds factor will be less of an concern. notice I said less lol
yeppers. and a pencil & paper, & grade school math, one can factor in the reynolds equation
and compensate. however I'm convinced is you scale down a warbird along with scale weight
the reynolds factor will be less of an concern. notice I said less lol
I looked at your original post about the P-40 and all the other posts, would you please give us your definition of "scale weight"? Are you simply dividing the weight of the 1:1 scale plane by the scale factor of the model?
02-04-2011, 08:54 PM
#49
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RE: Wing Loading
yah.. i want my 1:7 P-40 to weight 1142lbs.. please. 23lbs is about the scale weight.
so tell me, what else am I not good at? as you said to me.
02-04-2011, 08:57 PM
#50
RE: Wing Loading
Explaining what "scale weight" is. What did you do to come up with this number?
And if you'll take that chip off your shoulder, and read what I said, in context, about wind tunnels, my one statement concerned your rather flippant disreguard of why wind tunnels do what they do so well.
It isn't a SWAG, all the factors that you are telling us in your ONE comment are unimportant in the tunnel are the very reason the tunnel is used, not just throw a model in there and you get direct correllation. You have to know the effects of the 1:1 scale air, accounting for local pressure, humidity, temperature, density to make that time in the tunnel result in success.
And if you'll take that chip off your shoulder, and read what I said, in context, about wind tunnels, my one statement concerned your rather flippant disreguard of why wind tunnels do what they do so well.
It isn't a SWAG, all the factors that you are telling us in your ONE comment are unimportant in the tunnel are the very reason the tunnel is used, not just throw a model in there and you get direct correllation. You have to know the effects of the 1:1 scale air, accounting for local pressure, humidity, temperature, density to make that time in the tunnel result in success.