Angle of Attack

Any DA40 related topics

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rwtucker
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Re: Angle of Attack

Post by rwtucker »

Erik,

I am far from an expert but the CFI/Sales person who I bought mine had worked with the company for years. He said the test pilots had a hard time getting one to spin and that it would not spin at all under certain load and CG configurations. This belief was confirmed at my visit to the factory. I was also told that while a normal spin recovery procedure would not hurt, all that was necessary was to reduce power to idle and let go of the controls. The aircraft appears to be pretty spin resistant.

Important to note: all of this is verbal report. I suppose there is someplace that we could read about the certification runs. I know there was a lot of press when Cessna's new Light Sport went into a flat spin and the test pilot had to bail.

P.S. I just viewed the U-tube video that was posted while I was writing this. Assuming it is real, it would be interesting to see what modifications were made to the test aircraft.
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Re: Angle of Attack

Post by Gnomad »

Was running out the door earlier and didn't have time to find the more detailed DA40 spin testing video from Diamond. This one details entry and recovery info along with split screens of PFD and stick/rudder inputs. ...again don't try this at home! ;)

p.s. Oh and I love the final RTB maneuver at the end!

http://m.youtube.com/watch?v=GQXLUaA3yo ... QXLUaA3yo4

[youtube]http://m.youtube.com/watch?v=GQXLUaA3yo ... QXLUaA3yo4[/youtube]
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Re: Angle of Attack

Post by CFIDave »

I'm guessing the DA40 NG model shown in the video doesn't have 50 gal fuel tanks and hence has less polar moment of inertia out in the wings, which is why it passed spin certification tests despite having winglets.

I seem to recall that for a short time Diamond Canada was planning to offer retrofit winglets for 2007 DA40 XL owners who wanted to reduce the DA40's wingspan and better fit their aircraft into tight hangar door openings.

However when Diamond conducted flight tests, they discovered that when flying with CG at the rear limit, the weight of extra fuel in the 50 gal extended fuel tanks (extra weight placed outboard on the wings) -- combined with winglets -- delayed spin recovery beyond the 1.5-2 turns needed to pass spin certification tests. The result was that winglets were never approved for any DA40-180 models (particularly with extended range fuel tanks) and some 2007 DA40 XL buyers were provided with small refunds to compensate them for the lack of promised winglets.

Just a reminder: Unlike the DA20, the DA40 has never been certified for intentional spins. However, certification testing requires the aircraft manufacturer to demonstrate spin recovery (or an equivalent level of safety provided by a ballistic recovery parachute in the case of Cirrus) -- hence the video shown above.

So it's certainly possible to spin a DA40 (and to get back to the original thread topic); an AoA indicator would provide additional indication to the pilot that he/she might stall the aircraft. And as everyone knows, unless an aircraft stalls, it can't spin. :-D
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Jeff
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Re: Angle of Attack

Post by Jeff »

CFIDave wrote:

Just a reminder: Unlike the DA20, the DA40 has never been certified for intentional spins. However, certification testing requires the aircraft manufacturer to demonstrate spin recovery (or an equivalent level of safety provided by a ballistic recovery parachute in the case of Cirrus) -- hence the video shown above.
Just a slight correction this one. In fact, there is a model of the DA 40 that is approved for intentional spinning. That is the DA 40 F model (with carb IO-360). The approval requires a jettisonable canopy as well. As I recall it there were only a couple of these configurations that were actually sold and both of them are in China.
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rwtucker
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Re: Angle of Attack

Post by rwtucker »

Jeff -- Do you recall the wing configuration of these few spin-approved DA40's?

Eric -- All of these videos seem to be the NG and winglets. Is there any spin data out there on the "standard" DA40 wing?
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Re: Angle of Attack

Post by Gnomad »

rwtucker wrote:Eric -- All of these videos seem to be the NG and winglets. Is there any spin data out there on the "standard" DA40 wing?
It's just one video, really. The other one just has clips of the test "with music" ;) I'm not aware of any other spin data/videos, although there is some other interesting stuff Diamond has put on YouTube. Their two accounts, that I'm aware of, are: DiamondAircraftMedia and DiamondFlightTest

I had been following this AoA thread and when the discussion turned to how hard the DA40 was to spin, thought I'd throw it out there.
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Re: Angle of Attack

Post by Lance Murray »

I just watched a video of General Chuck Yeager saying that an angle-of-attack indicator is a "stupid instrument. If you don't know what the angle-of-attack is on an airplane you shouldn't be flying". He isn't a shy one.
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Re: Angle of Attack

Post by Moonshine »

rwtucker wrote:Jeff -- Do you recall the wing configuration of these few spin-approved DA40's?

Eric -- All of these videos seem to be the NG and winglets. Is there any spin data out there on the "standard" DA40 wing?
I'm not Jeff, but read up on those, since mine is FC.027, and the "China spinners" are FC.028 and FC.029

It's a regular DA40F wing (same as DA40), 40gal fuel. The only thing they did to the 40F was to make the front canopy jettisonable (regular non-XLS canopy) and bolted on a lighter MT fixed pitch prop (as opposed to my chunk of metal Sensenich)
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Re: Angle of Attack

Post by rwtucker »

Max, So are your wings 39-1/2 ft. or so without winglets but with the slight winglet-like up-curve on the tip trailing edge (sorry, don't recall the name of that tip)?
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Re: Angle of Attack

Post by Moonshine »

rwtucker wrote:Max, So are your wings 39-1/2 ft. or so without winglets but with the slight winglet-like up-curve on the tip trailing edge (sorry, don't recall the name of that tip)?
See photo here http://www.diamondaviators.net/forum/po ... tml#p48650 - just a regular DA40 wing
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