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All techie stuff here
User avatar
By waveview
#384129
Interesting how military spec aircraft have been using this technology for pilots to fly better/safer for quite a long time. Does an AoA indicator have any application in hang gliding?

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User avatar
By NMERider
#384130
waveview wrote:...Does an AoA indicator have any application in hang gliding?
Yes. It has a big effect on climbing ability and can also be used for a stall alarm or calibrated for optimum flare window. Right now all we have are Telltale yarns on our upper surface that are difficult to see but useful if you can see them. They are positioned to indicate best sink rate when the point sideways but not backwards.
User avatar
By NMERider
#384136
waveview wrote:This FAA document from April 2015 also talks about the advantages of Angle of Attack (AoA) indications over a simple air speed based stall warning for general aviation aircraft.
http://www.faa.gov/regulations_policies ... dendum.pdf
Belite makes an AoA indicator for ultralights. http://www.beliteaircraftstore.com/angle-of-attack/

For hang gliders the locations of airflow separation are important. If there was a way to look at or monitor strategically placed yarn tufts without having to roll sideways and look up that would be pretty cool. A camera mounted on a kingpost with a remote monitor on the control bar to view the tufts live might be fun to experiment with.
User avatar
By dave hopkins
#384137
This reminds me last spring I designed and bought the hardware to build a stall warning device. It would use the reversing air flow of the beginning of stall mush to activate a buzzer. Bought the stuff at radio shack.
It would use a tuff that is a conductor. Like a carbon yarn. When the reversing air flow flips it it would hit the other contact and sound the buzzer. FLARE! Or pull in a bit if you want efficient flight. It uses a Nine volt battery.The buzzer would be on the down tube. I thought it would help hit the flare window on my VR. It could save a pound in. I got distracted and didn't start testing it. But feel free?

Dave
User avatar
By waveview
#384138
NMERider wrote:Yes. It has a big effect on climbing ability and can also be used for a stall alarm or calibrated for optimum flare window. Right now all we have are Telltale yarns on our upper surface that are difficult to see but useful if you can see them. They are positioned to indicate best sink rate when the point sideways but not backwards.
I have a wing that makes quite a lot of noise and vibration as it gets close to stall sometimes. Would it be possible to build a simple devise that drums the top surface of the sail as the stall (air flow separation) at the centre section of the wing occurs? Sound or vibration feedback from the telltale may work.
User avatar
By waveview
#384139
dave hopkins wrote:This reminds me last spring I designed and bought the hardware to build a stall warning device. It would use the reversing air flow of the beginning of stall mush to activate a buzzer. Bought the stuff at radio shack.
It would use a tuff that is a conductor. Like a carbon yarn. When the reversing air flow flips it it would hit the other contact and sound the buzzer. FLARE! Or pull in a bit if you want efficient flight. It uses a Nine volt battery.The buzzer would be on the down tube. I thought it would help hit the flare window on my VR. It could save a pound in. I got distracted and didn't start testing it. But feel free?

Dave
Dave, great idea.
User avatar
By NMERider
#384142
waveview wrote:
NMERider wrote:Yes. It has a big effect on climbing ability and can also be used for a stall alarm or calibrated for optimum flare window. Right now all we have are Telltale yarns on our upper surface that are difficult to see but useful if you can see them. They are positioned to indicate best sink rate when the point sideways but not backwards.
I have a wing that makes quite a lot of noise and vibration as it gets close to stall sometimes. Would it be possible to build a simple devise that drums the top surface of the sail as the stall (air flow separation) at the centre section of the wing occurs? Sound or vibration feedback from the telltale may work.
I don't see why not. It may take a bit of experimenting to tune the system. Might even be able to create different pitched sounds for different airflow separation lotions too. Perhaps Mylar film or thin carbon fiber sheet. I really can't predict what would work well and still be practical. Latex sheet under tension might drum loudly on the sail. Hmmmmmmm.

I can hear the airflow separate on my T2C 144 but not so much on my Sport 2.
User avatar
By waveview
#384154
Looks like the short takeoff and landing STOL aircraft have been using these simple AoA (air pressure differential) instruments for a while now. They also go by the name of "lift reserve indicators" . Looks good - no batteries required.
http://www.stoneylake.org/pipcom/AOAr.htm
User avatar
By jj colorado
#384155
AoA indicators have been around and in use for more than a decade and stall indicators arent much different.

ez to setup for a hg BUT unless you plan to do high speed stalls, you already have one. Back pressure on the control frame.

our hgs have a lot of wash out in the wings so the wing doesnt stall all at one time. the root stalls long before the tips. so any stall indicator needs to be set for when part of the wing is stalled. but given the large amount of washout in the wing you can feel the bar pressure or lack thereof as the center stalls.

learn to hold the control frame lightly and feel the wing. it is a built in stall indicator. dont rely on a device to compensate for not learning to feel the feedback of the wing.
User avatar
By AIRTHUG
#384189
+1 to what JJ said ^

Also, don't forget the stall yarns on the top surface... strategically placed by the manufacturer (ever ask yourself why they are where they are?) You sure won't be using them to judge flare timing while landing... but you can get an idea of how close to stall "trim" is- or use them to tweak that- and you can get high and practice over and over feeling the glider's feedback right at the onset of stall.

Also also (LOL)- I can't speak for an ATOS, but for a flex wing hang glider... I'd suggest waiting to flare until right before stall is still too late. I've written in the past about how doing a slightly climbing flare, which I describe as "a quarter-loop" because that triggers the right mental image, is the best way to use physics to your advantage and get a full-stop no step landing (even in no wind).
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