peterzabriskie
Junior Member
"Did I make that part the best I possibly could have?" Unknown
Posts: 99
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Post by peterzabriskie on Jan 15, 2012 13:51:23 GMT -5
Hi 4trade....please accept my apologies, I do not want to shoot the messenger. You are giving my better specifics now with sq/ft vs weight but I am confused how can the Sonex be LSA when it so close in size and weight to the Sonerai?
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4trade
Junior Member
Posts: 51
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Post by 4trade on Jan 15, 2012 14:00:48 GMT -5
Sonex got 98 sq/ feet wing area and flaps. RV 3 got only 90 sq/feet but slightly better airfoil for lift, so Sonex really need that 8 sq/feet more wing to same stall speed. Both planes stall approx same speed.
Even with flaps Sonerai need lot more wing than 84 sq/feet to stall at LSA numbers. My guess is that 100 sq/feet and flaps will do the work with original airfoil.
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4trade
Junior Member
Posts: 51
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Post by 4trade on Jan 15, 2012 15:01:18 GMT -5
I must add some real Sonex numbers here, because we been talking that plane in this subject.....Sonex claims stall speed 46 mph clean, without flaps..... Not true. That may be done with very light plane and heavy headwind, measured on a ground, but not at gross and calm weather. That wing area (98 sq/feet) and gross (1100 lbs) coefficient lift should be 2.13.....and this airfoil (NACA 64-415) Cl is 1.5 at theory....so in a real word 0.85 X 1.5 = 1.275 When i put these real numbers at calculator....stall speed is really 60 mph clean. It must be only 625 lbs heavy to achieve 46 mph stall clean. Sonex numbers is just bull...advertiser´s one! That plane achieve LSA stall slightly...i mean barely...not with some margin. These kind of numbers is real eye opener....most people really trust those numbers what designer´s advertise. I think that´s really wrong to tell false numbers for client. Average client don´t have enough information to tell there is something wrong with it. Think that you choose design with wrong stall numbers, and build that plane years.....dreaming that one day it will land your own field at countryside....and when plane is done, find out that stall is 10-15 mph more than ad´s...so you need much more approach speed..and longer field to land that you own....argh! I use TOW (Theory of wing sections) for airfoil lift and drag numbers in here, those wing sections in that book are NASA wind tunnel tested, real and proof. If somebody want to check it, here: www.ajdesigner.com/phpwinglift/wing_lift_equation_force.php
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Post by dayflyer47 on Jan 15, 2012 21:49:35 GMT -5
If the new rule or exemption passes that the aopa and eaa introduces to the faa then it won't matter a bit, a sport pilot will be able to fly anything up to 180hp and 4 seats but still only allowed to take one passenger. We are waiting to see how it comes down. It basically does away with the need of the third class medical except for night flying and of course for payment.
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4trade
Junior Member
Posts: 51
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Post by 4trade on Jan 16, 2012 4:31:41 GMT -5
That sound great!
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hans
Full Member
Posts: 166
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Post by hans on Jan 16, 2012 5:17:28 GMT -5
If the new rule or exemption passes that the aopa and eaa introduces to the faa then it won't matter a bit, a sport pilot will be able to fly anything up to 180hp and 4 seats but still only allowed to take one passenger. We are waiting to see how it comes down. It basically does away with the need of the third class medical except for night flying and of course for payment. That will never make it into our European ELA (LSA counterpart) that is about to be launched... Hans
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4trade
Junior Member
Posts: 51
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Post by 4trade on Jan 16, 2012 5:47:27 GMT -5
Hans, it may happen, it just take another 15-20 years ;D
I think we are that much behind....
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hans
Full Member
Posts: 166
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Post by hans on Jan 16, 2012 7:35:30 GMT -5
Hans, it may happen, it just take another 15-20 years ;D I think we are that much behind.... I'll be dead, buried and decomposed by then.... btw. have you ever flown a Cassutt? How does it compare to a Sonerai? Hans
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4trade
Junior Member
Posts: 51
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Post by 4trade on Jan 16, 2012 7:53:25 GMT -5
No, this is my first homebuild. I haven´t fly Sonerai either. I was very close to build Sonerai but go with Cassutt at last. Both planes is so close structurally, that i spend time in here too...i might find something good ideas....
Our Administrator Schmleff (Jeff) is building Cassutt and i think he is best to tell us when it´s ready. I wait what he say it too....
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Post by raceair on Jan 16, 2012 8:54:39 GMT -5
I have hundreds of hours of Cassutt 111M and Sonerai 1 flying time. A Stock 111M Cassutt has 66 sq. ft. of wing, and they 'average' 560 lbs. empty weight with Continental power. A Sonerai 1 has 75 sq. ft. of wing, and they 'average' about 510 lbs. empty weight with VW power. Don't let the Marketing info on the Sonerai 1 let you believe that you can build a 1 at 440 lbs. empty weight........ There are many, many close comparisons between the two, but the big differences are stall speed due to gross weight and wing area differences, and climb rate differences because of the Cassutt having 40% more horsepower, and approach speeds, once again, due to wing area and gross weight. Routinely, My Cassutt with half fuel, and myself, stalled at 75 to 80 mph indicated. My Sonerai 1, 62 to 66 mph...... One interesting comparison, is that the Cassutt is easier to land, once on the ground and rolling. This is due to the Landing gear placement/ground C.G. position between the two airplanes. A stock Sonerai one 'rolls out' more like a Pitts, and the Cassutt by comparison is a lady on the ground......Just be light on the brakes with a Cassutt, it can be up on its nose much easier than the Sonerai 1....Ed Fisher
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hans
Full Member
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Post by hans on Jan 16, 2012 9:54:13 GMT -5
Hi Ed, as I only have a few hours of Sonerai-II under my belt, and no other powered taildragger (but many hundreds of flights in gliders some decades ago) unfortunately I cannot relate to any of the other aircraft types you mention, other than understanding the logic between wing area / power / stallspeed differences. It does make for an interesting read! Thanks! Hans P.S. so I gather from all this that as soon as I really feel confident and am consistent in my S-II, a Pitts would make for an easy transition? That makes me scratching my head... Roadmap towards P51, yes please ?
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Post by raceair on Jan 16, 2012 21:51:41 GMT -5
Hans....Actually, the ground handling characteristics of the Sonerai that I was comparing to a Pitts was a Sonerai 1....The Sonerai -II airframes are much easier to land an roll-out than the Sonerai 1. But, yes, the Sonerai -II will better prepare you for a Pitts than a Cub will....Ed F.
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Post by paul57 on Jan 17, 2012 20:51:14 GMT -5
Can anyone answer my question? Does the fuselage contribute to lift? Wing equations are great, but I'm more interested in the plane as a whole.
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hans
Full Member
Posts: 166
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Post by hans on Jan 18, 2012 2:59:25 GMT -5
Can anyone answer my question? Does the fuselage contribute to lift? Wing equations are great, but I'm more interested in the plane as a whole. according to slender body theory, any longish body at an angle of attack will create some lift, but that may not all be good if you stick wings on it. The flow pattern around that body (also put into a slightly circular motion by the propeller slipstream) may negatively interfere with the flow pattern around the wing, negating its own lift. Do what 4Trade showed us: take a real measured stall speed and calculate whether the Cl needed for that speed is still realistic for the wing section in use (of course at the correct Reynolds-number and reduced for the actual wing aspect ratio). If Cl seems a bit too high, fuselage lift might just have entered the equation after all... Hans
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4trade
Junior Member
Posts: 51
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Post by 4trade on Jan 18, 2012 6:56:26 GMT -5
Yes, i remind that previous example just show very simply way to have some kind of clue of wing lift/ stall speeds. There is lot of more things to considered when actually design or calculate a wing. These examples is actually "best case scenario" type, and usually lift of wing is smaller....if there is twist or "not so perfect" surface of low aspect ratio or.... Looks like with those numbers (stall/ lift) that Sonerai frame don´t generate lift....and most of airplanes fuselage don´t generate noticeable amount of lift, unless it is design like it....like flying wing. Hans is absolutely right, you should use data with correct reynolds number for airfoil when calculate wing. You find what Re is and calculator for it here, NASA site: www.grc.nasa.gov/WWW/BGH/reynolds.html
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