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Old Feb 05, 2006, 10:17 AM
Nick Radle
Bodywerks's Avatar
United States, AZ, Tucson
Joined May 2004
1,705 Posts
Quote:
Originally Posted by tIANcI
There is no way you can compare the KM with the new Extra 300, how can you? Both are designed so differently, one is a 40" plane whilst the other a 45". I have not flown the KM yet but I can tell you that the Extra is so different from my Prodigy. The Extra is very gentle, has a 'smooth' feeling, I must say that the landings are so gentle, like a Magic Extra.

The offered power combo is just right and its not expensive too. What you want is a power system that can turn a 12x6 at about 7,750 RPM at the least to really enjoy this plane for 3D. I used a 11x4.7 SF and it did not go down well. The 12x6E is spot on.
Dude, this guy was trying to compare this plane to a 16 ounce built-up wood kit with like a 35" wingspan and complaining about how heavy this 300 seemed compared to it.
I am, by NO MEANS, comparing flight characteristics between the two. I was just pointing out that, if Mr. Luv2fly wants to compare wingloadings, he needs to do it with more similar sized planes. To be honest, I hope and anticipate that this 300 will fly nothing like the KM: it is by no means a precision plane, IMO, and has tons of bad habbits, albeit still fun to fly.
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Old Feb 05, 2006, 11:09 AM
Xtreme Nut
Kuala Lumpur, Malaysia
Joined Oct 2005
2,046 Posts
Body - I did not mean YOU, I meant the manner of comparison. From what you say I think I should sell my KM now before it arrives!!! Hahahahaha ...

Okay .. as for wing loading I will say that I have flown the EF Extra 300 and I really do not care about the wing loading because I will tell you it is just so light in the sky. My first few landings were really difficult as the plane was floating, there was no head wind as I flew her early in the morning. The way it lifts off is like say a H9 Extra 260 taking off, it lands slower than my Prodigy, ICON and Hot Point.

The EF Extra is very precise to fly, when Chris says its great for IMAC he means it. I am not a real 3D nut, for me planes are about fun ... this one really is. I mean the KE has almost no coupling. I did not use any mix, only adjusted it by shifting the CG.

Its very true that a planes wing loading will tell us about how it flies but then design comes into play and I learnt this from the EF Extra 300.

I was with Chris a few days back and he showed me the video of the new 50cc gasser that we are starting to manufacture for him. I used to think planes will too light a wing loading will fly like a Magic and that's all it can do. Seeing the new gasser prototype video I was amazed. It may have a very light wing loading but it does not fly like a Magic. Food for though ..
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Old Feb 05, 2006, 12:34 PM
edible_engine's Avatar
Just south of Cambridge, UK
Joined Oct 2003
982 Posts
ok, all this comparison stuff is annoying me. How can you compare one plane to the EF extra when NOBODY (apart from tianci, and some of the atlanta hobbies people) have flown this plane??? it aint possible. Ive seen it, in the flesh, its light, large and looks beautiful, but i cant compare it to the KM or the prodigy as i havent seen those ones in real life. see what im getting at? Just wait till this plane comes out, buy it, fly it, then compare it!

Ian
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Old Feb 05, 2006, 12:54 PM
Nick Radle
Bodywerks's Avatar
United States, AZ, Tucson
Joined May 2004
1,705 Posts
Agreed.
Tianci, don't sell the KM. It has it's good points and is still fun to fly.
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Old Feb 05, 2006, 01:16 PM
Registered User
Essex, UK
Joined Dec 2003
579 Posts
I think all these comparisons are being made because no-one's got the planes yet...just chill out guys and be patient as edible engine said!!! Enjoy the video or something!! By the way, anyone know who they used for the music - its pretty good stuff!!?
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Old Feb 05, 2006, 07:04 PM
Xtreme Nut
Kuala Lumpur, Malaysia
Joined Oct 2005
2,046 Posts
Yeah let's not really compare planes, each plane is peculiar, also different people like different types of planes (we know the VMAR types don't we?). In as much as the EF Extra and the Prodigy are different I will say they are both fun to fly. Its like apples and oranges. All I will say is that you guys are going to have a ball with this plane, its a very likeable one. I call it a very neutral plane that most people will like.

Only person I pity is Freestyle-RC ... he has the plane but cannot get it up yet!!! Hehehehe ... torture!
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Old Feb 05, 2006, 07:09 PM
Nick Radle
Bodywerks's Avatar
United States, AZ, Tucson
Joined May 2004
1,705 Posts
I heard a rumor about Feb. 15th would be when they start shipping them out....Until then, I can make no promises as to my rantings on this forum!
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Old Feb 06, 2006, 01:09 AM
iumop ap!sdn w,I
G.P.'s Avatar
Joined May 2005
6,458 Posts
Quote:
Originally Posted by sukhoi26mx
Shawn,

It is called cubic loading and basically normalizes wing loading when scaling airplanes up and down. When airplanes size change, their ability to carry weight and retain similar feel also changes. For this reason, wing loading doesn't really tell the whole story. For instance, my 42% Extra has a wing loading of nearly 40 oz/sq.ft. and flies light as a feather. Try flying a foamy with that loading... but if you keep the cubic loading (and planform, incidences, area ratios, etc...) similar, they'll have a similar feel. Here is a page with a calculator on it. Doesn't take into account wing thickness or airfoil selection, but by the looks of it, EF has chosen a relatively thin section with a sharp leading edge, which in my opinion is a great decision (versus a thick section with a blunt LE). Anyway... here's the calc page.

http://www.ef-uk.net/data/wcl.htm

In my opinion, the EF Extra is going to fly very light. It looks to be a very appropriate loading for the design. Judging from the video, it looks to be exceptional.

Scott
Scott,

Thanks for your excellent explanation on how an airplane is affected by wing loading. I have always wondered why you could increase wing loading as an airplane increased in size and have it fly the same as a small one with lighter wing loading.

It makes sense that a 40% model would appear to be flying slow and floaty at a wing loading that is much higher then the average foamy. Due to it's size a 40% model would appear to be going pretty slow at an airspeed of 20 knts (just for example), while a foamy would appear to be doing mach 1 at 20 knts of airspeed. A 40% model with a wing loading as low as a foamy's would probably fly just as slow as a the foamy, but would appear as if it was hardly moving. It's all about perception.

From your explanation I concluded that a higher wing loading is actually required as a model increases in size, just to help it groove through tricks and to feel "right". Am I correct?

Thanks again,
Greg
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Old Feb 06, 2006, 05:09 AM
Nick Radle
Bodywerks's Avatar
United States, AZ, Tucson
Joined May 2004
1,705 Posts
Yes. To give you an idea, a full scale aerobatic plane has a wingloading of somewhere in the area of 50 pounds/sq.ft., yet still flies pretty light.
The basic reason wingloading gets heavier is because, for one, gravity affects things more as their mass and size increase. That's why you can drop a beetle off the top of a building and it will just hit and walk away, but if you follow it down, you'll be a splat on the ground.
The reason a larger plane flies as light as a foamy has to do with the fact that they both fly in the same air density, but the foamy doesn't move through the same amount of air as the larger plane. This is the basic key to a reynold's number. He found that, when you put a scaled down model in a wind tunnel, you had to increase the air density by the same factor that you scaled down the model to get accurate accounts of its aerodynamics - it's just one of those phenomina.
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Old Feb 06, 2006, 11:51 AM
Scott Stoops
sukhoi26mx's Avatar
United States, CO, Longmont
Joined Mar 2002
8,411 Posts
Quote:
Originally Posted by G.P.
Scott,

Thanks for your excellent explanation on how an airplane is affected by wing loading. I have always wondered why you could increase wing loading as an airplane increased in size and have it fly the same as a small one with lighter wing loading.

It makes sense that a 40% model would appear to be flying slow and floaty at a wing loading that is much higher then the average foamy. Due to it's size a 40% model would appear to be going pretty slow at an airspeed of 20 knts (just for example), while a foamy would appear to be doing mach 1 at 20 knts of airspeed. A 40% model with a wing loading as low as a foamy's would probably fly just as slow as a the foamy, but would appear as if it was hardly moving. It's all about perception.

From your explanation I concluded that a higher wing loading is actually required as a model increases in size, just to help it groove through tricks and to feel "right". Am I correct?

Thanks again,
Greg
Greg-

You bet. Your assumptions are correct. There is definately a minimum wing loading that I consider reasonable for each size airplane to retain energy and track well through aerobatics, as well as a maximum loading that is reasonable for high alpha performance and pitch response. I prefer to use cubic loading as it more accurately describes the performance you can expect when comparing one model to another.

As far as size distorting our perception of speed, it definately does. I talked to George Hicks about that at length, and while he can turn it into an equation explaining it precisely, I can only relate the basic idea. Basically, the human eye/brain use object length to measure speed. So, we measure the length of the object visually, then judge its rate of speed by the time it takes to travel a length or number of lengths (in most cases length of the fuselage). On a smaller model, at 20 mph, it will travel say 20 lengths in a certain time, while a bigger model may only travel 2 lengths in that same time. Same speed, different perception of speed. Makes the 40%'ers look like they are floating by, when in reality they are not only travelling the same speed as the smaller model, but in reality probably much faster...

Scott
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Old Feb 06, 2006, 04:39 PM
Registered User
Joined Jan 2005
69 Posts
Quote:
Originally Posted by Bodywerks
Dude, this guy was trying to compare this plane to a 16 ounce built-up wood kit with like a 35" wingspan and complaining about how heavy this 300 seemed compared to it.
I am, by NO MEANS, comparing flight characteristics between the two. I was just pointing out that, if Mr. Luv2fly wants to compare wingloadings, he needs to do it with more similar sized planes. To be honest, I hope and anticipate that this 300 will fly nothing like the KM: it is by no means a precision plane, IMO, and has tons of bad habbits, albeit still fun to fly.
OK, I was with you all the way, my mini is also about 26 oz., until the "tons" of bad habits. While no plane will satisfy every flying style, I think my mini is (IMO) one of the best flying planes out there. I wish it had a little larger rudder and I have heard about it wanting to wing rock in harrier but in general I think it flies great. Am I missing something? And by the way (Luv2fly) it slows down really nice, you can flare over and over again on landings with no power on.
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Old Feb 06, 2006, 07:41 PM
iumop ap!sdn w,I
G.P.'s Avatar
Joined May 2005
6,458 Posts
Quote:
Originally Posted by sukhoi26mx

As far as size distorting our perception of speed, it definately does. I talked to George Hicks about that at length, and while he can turn it into an equation explaining it precisely, I can only relate the basic idea. Basically, the human eye/brain use object length to measure speed. So, we measure the length of the object visually, then judge its rate of speed by the time it takes to travel a length or number of lengths (in most cases length of the fuselage). On a smaller model, at 20 mph, it will travel say 20 lengths in a certain time, while a bigger model may only travel 2 lengths in that same time. Same speed, different perception of speed. Makes the 40%'ers look like they are floating by, when in reality they are not only travelling the same speed as the smaller model, but in reality probably much faster...

Scott
That's what I was trying to say! No wonder you write the articles and I don't!
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Old Feb 07, 2006, 09:54 AM
Registered User
W. Bloomfield, Mi
Joined Oct 2002
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subscribing.
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Old Feb 09, 2006, 08:49 AM
Truss-Loc Monkey
Stevens AeroModel's Avatar
Colorado Springs, CO
Joined Feb 2002
4,402 Posts
I sense an over simplification. I have it on good authority that SA has never shipped a box of sticks to a customer; precision crafted interlocking cut parts produced in short runs on US soil from hand sorted and grade selected balsa yes. Box of sticks?.... far from that

Both kit makers and ARF mfg's alike MUST ensure the structural integrity of the product they sell or import. Shipping someone a kit or an ARF to assemble doesn't immune you from disappointments that might arise from an improperly assembled or poorly engineered structure.

As for the topic at hand - I think it's fantastic that we are seeing so many high quality ARF's dedicated to e-flight. This one, in particular, I'm very fond of as I have great respect for the designer... Now let's pop the lid on that container and go fly eh?

-Bill Stevens

Quote:
Originally Posted by Bodywerks
I was just saying that the SA planes are a different animal altogether. They are a kit that you have to build, for one, and the fuse is a bunch of sticks that you glue together to get a fuselage-looking shape - not nearly as smooth and nice looking as this plane, IMO. Also, part of why they are lighter, too, is because they are not an ARF, and SA will not be held liable for any of the structural integrity of the plane. With ARF's the manufacturer has a reputation to uphold and doesn't want stories of his planes flying apart, therefore weight is sacrificed, slightly, to ensure a more durable setup.
I'm not knocking SA - they are a hometown manufacturer that is literally just down the street for me, but you can't come on here and compare them to this or any other ARF plane, since the ARF market is an entirely different venue than the kit market. Most people in the market for this plane are WAY more willing to spend $170 for this relatively light and very scale looking plane, already built and covered, than they are to spend $130 for a similarly sized box of sticks that they need to build, buy covering, glue, and paint and tools, and building board, etc. Building is a lost art. I even used to build GS planes professionally and use to build pretty nice planes for myself. But given the decent quality of ARF's and the fact that I spend more time flying, less time building, and the only thing I have wrapped up into the plane is money - not my heart and soul, I am a better flyer for it.
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Old Feb 09, 2006, 08:52 AM
Scott Stoops
sukhoi26mx's Avatar
United States, CO, Longmont
Joined Mar 2002
8,411 Posts
Quote:
Originally Posted by arenablimp
I sense an over simplification. I have it on good authority that SA has never shipped a box of sticks to a customer; precision crafted interlocking cut parts produced in short runs on US soil from hand sorted and grade selected balsa yes. Box of sticks?.... far from that

-Bill Stevens
Nicely put.

Scott
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