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Old 08-23-2013, 09:48 AM   #11 (permalink)
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I love those performance projections from an RC or computer modeling. So phony
with fixed wing aircraft, you get pitch stability 3 ways:
1: Downforce from a conventional tail. This by far is the most stable arrangement through the whole speed range.
2: A second lifting surface out front, a canard. This is the most efficient. It is also prone to really nasty behavior. Deep stalls you cannot recover from, annoying pitching action from simple rain, etc.
3: computer generated stability via fly by wire. Very nice for high maneuverability, very pricy, and deadly when it fails.

Here is a classic example of positive pitch stability. During my CFI training, we were out spinning the cessna 150. My instructor showed me a neat trick. Trim the aircraft for 65 MPH, then pull it up to stall. hammer a rudder and get it into a nice spin. Close the throttle.
Let go of all the controls!
It will nose down and recover from the spin immediately. Then it continues pointed down as the airspeed builds. It will then pitch up due to the trim being set for 65 MPH, and not exceed the yellow arc in the recovery. Still no pilot input whatsoever. Maximum airspeed was about 115 MPH.
Of course, you have to capture the plane as it pitches through level flight or it will go up and stall again

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Old 08-23-2013, 12:01 PM   #12 (permalink)
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Quote:
Originally Posted by skyking View Post
Of course, you have to capture the plane as it pitches through level flight or it will go up and stall again
Remember you had to hold it into the initial stall after you set your trim.
It is important to note the plane will be naturally seeking the 65 you trimmed it at. It will only stall again if it has so much speed and energy that it exceeds the stall angle while trying to maintain the 65. Oscillations would be expected to reduce until the stability has returned.

I would be interested in the stall and stability characteristics of this Synergy plane and so would the designers. I cant wait to see the proto fly and hear about its performance.
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Old 08-23-2013, 12:04 PM   #13 (permalink)
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Quote:
Originally Posted by doviatt View Post
Remember you had to hold it into the initial stall after you set your trim.
It is important to note the plane will be naturally seeking the 65 you trimmed it at. It will only stall again if it has so much speed and energy that it exceeds the stall angle while trying to maintain the 65. Oscillations would be expected to reduce until the stability has returned.

I would be interested in the stall and stability characteristics of this Synergy plane and so would the designers. I cant wait to see the proto fly and hear about its performance.
It does pitch up enough on the first one to stall, or at least an abrupt drop through. After that it "falling leafs" to a stable condition after successive smaller oscillations.
You can see how the diesel engine is doing in other airframes. That is the exciting part for me, the diesel. I got my hopes up when Zoche was in development and testing, only to have it all evaporate.
I kept seeing a pair of those 300 HP beauties on the wings of the 310.
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Old 08-23-2013, 06:34 PM   #14 (permalink)
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Yeah, the radical (for aircraft) engine is the big part of these performance projections.

I wonder about this layout because of the short couple (distance along the centerline) between the front and rear lifting surfaces. What would conventional aircraft behave like if the empennages were shortened five feet? Everything still works according to flight theory, but the leverage is so short that I would think constant correction would be necessary to maintain level flight and keep oscillating to a tolerable level. So does the Synergy require computer controlled guidance? Is it capable of not only flat spins but tumbling spins? Scary.
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Old 08-24-2013, 12:24 AM   #15 (permalink)
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Frank, google this Synergy thing and read more about it. Engine is going to be a big part, yes. But no conventional aircraft design today will be capable of what I'm guessing too be 5 passengers in pressurized flight at 30,000 feet going 250-300MPH burning 5 gph doing so. I've come to understand that the higher and faster Synergy goes, the better it gets. The Cd is crazy low, this design really is unique.

The upper air foil is acting to create a venturi effect between the 2 wings, in addition, there will be no "Spinning Clouds" behind the Synergy as it flies because the placement and effect of the upper wing counteracts the vortex formation.

This is an amazing design, they've been playing with the 1/4 scale model for years without it stacking in or flipping out of control in mid-air.

Maybe something will go sideways with this design and project, I'm puzzled that it has been over a year since they thought they could get a full scale prototype flying. I'd think they'd want to get the first plane in the air as proof of concept and gathering data, then work out all the production stuff later. I also question why Boeing, Piper, or Beechcraft et al does not look at this and go Kazam and make a similar model.

Time will tell I guess, if it works as dreamed about, at least some of you can say you saw it here first.
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Old 08-24-2013, 12:49 AM   #16 (permalink)
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There have been tons of joined wing/box wing proposals over the years; Synergy claims to be different in that the others are all about upward lift while his upper surface acts as a conventional downward-pushing tail. I'll get excited when someone gets to fly in one and report awesome advances in the state-of-the-art.

That said, I don't believe it belongs in the category of the Ram Implosion Wing!



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Old 08-24-2013, 01:11 AM   #17 (permalink)
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Your Google searches make for a very important point, Frank. I don't see one picture of a real aircraft. Lots of models and computer renderings.
I started to think of modern design and realized that even the most celebrated modern designer, Burt Rutan, has/had not one certified production aircraft to his name (exception being influence of the beautiful but failed Beech Starship). This means a lot for design advancement but something big is missing for mass production certified aircraft. Physics, materials, and money probably have something to do with it.
I hate being a skeptic on this topic since aviation is my main passion but reality rules. I do hope some one breaks the trend.
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Old 08-24-2013, 01:25 AM   #18 (permalink)
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One of my most memorable childhood experiences was flying stick and paper box kites while others were flying plastic/vinyl bat kites. Something cool about the box kites. Synergy meets this cool factor (all of its plastic included).
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Old 08-24-2013, 01:34 AM   #19 (permalink)
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I got my first small plane ride from my uncle when I was a wee sprig; I used that opportunity to do an aero experiment, which was to make a parachute for an old differential gear I found out on the farm and throw that out the window of the plane. Surprisingly enough, he went along with it but the chute was a fail and I was very fortunate to not put that gear through the stained glass window of a nearby church.

Anyhoo, that's what really got my interest in aviation going. I eventually got pilot licenses up through commercial, multi-engine, instrument instructor, where aviation then took a back seat to my burgeoning ground vehicle design career.
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Old 08-24-2013, 10:30 AM   #20 (permalink)
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A Lot of the pictures you show are "Box Wing" configurations which the Synergy is not. Also, the 1/4 scale Synergy model flies, it isn't just a display.



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