Reflex wings for dummies (yes including you Dell)
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- čas přidán 27. 08. 2019
- Firstly... yes I know the audio is once again not the best... it’s not about being a great video maker it’s about the content! Adjust your volume settings both on the device hardware AND in the CZcams app. If you can’t work it out then don’t blame me!
This video is an initial attempt to get the message across about why a reflex wing is positively pitch stable and returns to its trimmed position when displaced by an outside influence as well as why a conventional wing is naturally unstable and therefore divergent if not actively flown. Ultimately the pendular effect tends to resolve things however conventional aerofoils are more inclined to collapse before the pendular action can restore matters in more active conditions.
For further information there is still some useful information that can be found on the Glenn Research Centre NASA pages although this is unfortunately rather dumbed down from the info that used to be available. Researching “reflex wing stability” via Google can still lead to some excellent theses giving good further reading.
One further thing... I mentioned incidence as being the angle between the chord line and the pilot. That really doesn’t say anything, my apologies as I was thinking on my feet as I went along! On an aircraft the incidence is the angle between the chord line and a suitable datum on the fuselage such as a line going from front to back. That datum line moves with the aircraft as it pitches. It just defines the angle the wing is set on the craft whereas angle of attack (alpha) is the angle between the chord line and the oncoming (relative) airflow. For our craft I would consider a suitable datum for the incidence of the wing to be measured is between the chord line and a line straight out in front of the pilot (that is reference to the pilot and not the ground!). In our airsport we have one unusual aspect in that our wing can pivot in flight around the wing attachment so the incidence of our wing is much more able to change in flight which then is usually followed by a change in angle of attack. - Auta a dopravní prostředky
I have been paragliding since 1998. In 2010 I decided to switch to a reflex paraglider and I bought OZONE Roadster I have flown with it in a variety of conditions (both free flying and with paramotor). In some very windy conditions I took advantage of it especially by avoiding being blown back the hill but in light wins I saw that the performance of standard paragliders was better in terms of staying in lift. Overall I can say that reflex wings have great speed and security performance however their trade-off is not generating enough lift in weak conditions. Overall, I am satisfied with this wing, still flying with it. You can watch some of my flights in my channel. Hope my comments are useful.
That was very helpful. I really appreciated this video. You made another video on the correct way to hold the throttle control s so the cable lays over your arm and so less likely to go back into prop. I flew 2 days ago and it's just part of my preflight setup , I allways meant to thank you
I recommend everyone who flies to have a watch of that vid !
Thanks Ian
Really good explanation! Thanks for sharing. I was hoping for graphics and your ‘old school’ method was spot on!
Excellent explanation. Clarified the mess for me beautifully.
Great video :-) thank you for taking the time to do this video
Could you cover ozone's sharknose tech?
Great explanation from an actual aeronautical engineer taking the "Super trainer" to task... well done sir! 👏
Patiently waiting fof Dells comment 😊 Superb video this, as is any coming from Ian.
You don’t have to wait for Dell’s comment. While you were waiting Dell was flying in the mountains at 1 pm in 100 degrees. Do you do that? Would you? Dell doesn’t use reflex and Dell outflys them all. If you have a video of yourself out piloting Dell I’ll watch and listen. Link please.
@@kcb5336 more like dell's off harassing wildlife and bring an altogether tool
Found this really helpful, great video thank you
I believe your the only person who can better explain how the Hadron XX flaps influenced the wing. I saw that somehow break the profile , but I would be very thankfu and appreciative for your explanation. I fly the wing quite often with flaps engaged.
With best regards!
Marius
Hi Andrei. With no flap deployed the Hadron XX effectively has the same amount of reflex at any trim setting. This is the same as Ozone wings and different to other Dudek wings which generally having largely increasing reflex the more released the trimmers are. Changing the trim setting on the Hadron XX consequently changes the incidence of the wing (relative to the pilot) which consequently impacts the angle of attack. Therefore on the Hadron XX trims in is the wing section at one angle of attack while trims out is the same shape wing at a lower angle of attack. On a Nucleon XX (for example) trims in is a wing section at a particular angle of attack while trims out is a different (even more reflexed shape) at a lower angle of attack. Do you see the difference? Most Dudek wings (other than the Hadron series) increase the negative curvature as the trims are let out but the Hadrons effectively don’t (same as Ozone wings). Now you asked specifically about flaps... the flaps on the Hadron XX are proper flaps like on a light aircraft. They operate purely on the trailing edge at the centre and change the airfoil to a much higher cambered one. On the Hadron XX we have gone from a negative camber (reflex) to a very highly positive camber which is why the wing goes all floaty when the flaps are deployed. The wing is now a regular paraglider and should now been flown actively as the relationship between angle of attack change and centre of pressure movement has reversed, ie it has become conventional. Hope that helps!
@@TogaSRS It helps, many thanks for taking the time to reply. I know about the constant reflex profile as also being the reason we could apply speed bar without releasing the trimmers. The flaps was a mystery for me, while I suspected that it change the wing in to a non reflex one, I still found it some how pitch stable with flaps engaged and this was the contradicted factor for me. Now it's clear. Many thanks again.
It was a good evenings discussion. I hope others can finally understand the concept rather than going on myths, wives tales and incorrect publications of old wings.
Great explanation...thank you. Do you know if the reason the Nuc is less efficient than the Hadron is because of the chamber change? Then again, the Universal is very efficient using that same principle. Any ideas?
The only reason Dell hates reflex wings is because the wing he sells (rebranded Cima) and therefore has exclusive rights to, is old non-reflex technology, so naturally he hast to bash everything and anything that is NOT his equipment.
Even though he has some moderately decent training videos, I can’t watch more than a minute of them as his personality gives me cold chills.🥶🥶
Cheers Ian, great explanation which has given me a better understanding of how our wings perform. Have subbed.
So if a reflex is more stable but has longer recoveries, would that make it better or worse for flying
I really want to get into this sport, and I've been lurking on the sidelines for some time. However, I'm a bit skeptical to pull the trigger due to misleading or inconsistent information. This style of education is exactly what this sport needs. More intellect, and less 'bro science' explanations. Thank you!
Don't wait any longer, pull the trigger. This is an amazing sport and you'd never regret it.
Macpara has a Reflex wing called Charger. It has wingtip stearing which is supposed to be used when trimmers are all the way out, ( Reflex setting. You stow main brake toggle and use the wingtip stearing toggle). Anythoughts?
Thanks for the great explanation. It's all clear now.
hi ian yes brilliant..informative..as you said though to personally reply..what is your oppinion of non reflex vs reflex..i have just got a new universal 1.1. just curious amd always keen to learn more.thanks again
Honest question here... if the reflex wing is so stable in full trim out mode ... why does the certification not bear that out?? My understanding is the reflex swings are only certified in traditional mode not reflex mode. Am I wrong here??
Honest answer here. Certification involves testing recovery, not stability. Reflex wings don’t recover as well as most traditional airfoil wings and that increases if you let the trim out on a wing where the amount of reflex increases with trim extension. Therefore if they do bother to put them through a proper testing house then they will test them at the trim setting that is most likely to succeed. However the testing houses are testing for a flight regime they are designed to not get into in the first place which is the crux of the argument about the validity of using collapse recovery as the benchmark for wing testing.
This helps thank you very much
Love the "Dell". Great video
Thanks goodness, dell is an absolute cheese ball it’s disgusting that he uses scare tactics to makes sales. Thank you for explaining and calling him out on his bologna.
I'm not a hater but that Dell guy instantly made me feel strange. He will deny everything and anything.
ranman58635 aye making your rounds on the paramotor related content!!
It’s like a cult his followers are die hard fans, sometimes I wonder if the “people” that comment on his videos are just profiles he made lmao 😂 I don’t have enough words for how I feel about him. I just feel bad for anyone who believes all the bs he says, everyone needs to do their own research in this sport, your definitely doing your fare share of it on the tubes! It’s great preparation paramotor school!
ranman58635
Mitch G does a really good explanation of reflex too!
@@nedmacallen well, im definitely not here to stir things up. Im just a little bored but you are right about a person here. With that said, i would like a good wing that i can rely on and im learning that.
@@nedmacallen i saw that yesterday. Why is it that two different people can have two different explanations of the same wing? Who is right?
Very informative Ian well done, Thanks for clearing up the garbage going around about reflex.
So why do the B,C & D lines go slack on a Dudek reflex wing when fully trimmed out? (Mitch G's vid) Surly the loading on the lines should stay the same at all trim settings if the wing profile stays the same?
Most Dudek wings increase the negative camber as the trim is let out. The effect of that is that the max thickness of the wing shifts forward shifting the lift distribution forward. Once the trim position is set any a of a change due to lift or sink still has a positive stabilising effect but around a point even further forward.
Very well done Ian, thank you. However, you didn't mention the effects of the depth of the carpet nap on the AOA. NASA's working on it...
Thanks for the explanation Ian, it's certainly given me food for thought...
Can you “prove” somehow visually that the center of pressure moves back with a reflex wing?
www.mh-aerotools.de/airfoils/flywing1.htm
Hi, Ian. I'm trying to understand. I did not major in physics nor am I a mathematician so perhaps you can answer this line of question so that a layman can understand. I'll admit to having watched "SuperDell's" (uggh!) video and then watched yours. He used the expression, "You can't push a string", and I'm trying to understand how the trailing edge of a soft para-wing can hold that upturned shape when air is flowing over the top surface, exerting downward force on that upturned edge. In our discussion, a friend suggested it's possible that "You're not so much pushing up on the rear as you are letting the lines out so that the back of the wing becomes taught at a higher angle?" As I said to him, I understood his concept, but I don't see how releasing the pull of the rear lines would result in the rear of the wing holding that upturned shape unless there's significant pressure against the bottom that could cause it to hold that shape despite downward force from the airflow over the top of the wing. If that were the dependency for the reflex shape to work, that upward force would need to be consistently stronger than the downward force that is then causing the increased angle of attack. I hope my question is clear and that you can respond to his terms that don't include mathematical formulas. Thanks in advance!
The ram air profile in modern wings forward section (sharknose in ozone as an example) when moving forwards, creates a positive pressure internally. With all gliders "falling" at a sink rate (dependant upon the wing) the wings shape loads the top surface which again creates a 'pulling force' which is pulling the upper and lower sections apart slightly. These two forces combined make the wing stable up beyond any lift vector point in any angle of attack. In reality the pressure differential in level flight between the internal section and the lift forces of any wing only needs to be 1% higher to maintain internal pressure but in reality a EN A wing can have up to 40% a B around 30% and then C and D vary greatly depending upon the wing.
You didn`t explain why the chord line on a reflex wing ends part-way along the top surface of the wing rather than at the trailing edge as in a conventional glider?
And in your diagrams, the CoG (the pilot) is always depicted directly underneath the wing. This isn`t exactly the case during powered flight is it - the pilot (under power at least) is always slightly forward?
Does it still remain true that the centre of pressure moves forward within the wing when trimmed fully out compared to trims in (and this theory of self-stabilisation due to the centre of pressure moving fore and aft according to the AoA is in addition to the trim setting related CoP movement)?
The chord line doesn’t end if it should happen to be above the upper surface of the wing! It is a theoretical line between the leading edge and the trailing edge. That is the same for any wing section whether reflexed or conventional. With regard to the suspended mass being directly underneath... as I mention there are some simplifications that need to be accepted to make a point that can be understood by anyone coming at this afresh. There are many more however the need is to keep it simple so the basic concept is understood. I am a little concerned when you mention the centre of pressure “within the wing”... the internal pressure and the centre of pressure are completely different things that should not be confused. I am not quite sure what you are asking in the last question. Are you assuming a wing that increases the amount of reflex profile with trim release as well as changing incidence (and therefore alpha)? I presume it’s that you mean rather than a constant profile reflexed wing?
Well done
This was excellent. Glad I came across this video. Thank you!
Thinking of getting into the sport can you point in the direction of a good EN-A certified reflex wing. Thank you in advance.
Dudek Universal. 1.1 is arguably the best on the market
Instant thumbs up for the dell comment 🤣😂
Nice. Check out the Yank version on Mitch G channel. Great you guys making these videos
nice level headed excellent how it works video .. No name calling .. Just good solid presentation of how it works . No screaming ,yelling rolling eyes . just the presentation of FACTS . Brilliant well done . top man . Such a shame that a certain group of instructors are seemingly unable to put their personal aims to one side and present the facts as you have done . I have followed your presentation closely and can glean that the reflex wing will automatically adjust for some levels of turbulence . Whereas any non reflex design will need to be actively flown through sketchy / undesirable conditions . . The question with pops up in my logic filter .WHICH ONE is more likely to end in tears . IE which one will return to a flying wing rather than a bag of twisted up shroud.. all things being equal . dramatic statements like face down , plant etc are not very constructive . I have dabbled in Lawn darts( hang Gliders ) and flown as passenger on a paraglider and flown [passenger in a trike hang glider .. The Hang glider trike was the most controllable with excellent feedback .
A lot of paraglider wings these days "bite" into thermals... Does that mean they're reflex? How about pitch stable wings..
Great explanation. I was watching this video czcams.com/video/HV9BNn47Ejw/video.html where at 9:30 the author explains how he got a collapse on a reflex wing. He was accelerated and he went off the speed bar just before the collapse. This is the right behavior on conventional profile wings. I was wondering if on reflex wings, the reaction of releasing the speed bar while encountering turbulence is the right thing to do. Maybe you can help me understand this?
It could be that the combined angle-of-attack increase of entering lift and dumping speedbar caused the wing to surge forward (centre-of-pressure moves back) enough for the angle of attack to go negative? If at low altitude, could also be that by the time the wing surges, it hits sink at the "far side" of the thermal. Depending on the glider design, it's either best to stay fully accelerated through turbulence, or go trims in and fly "actively" like a normal paraglider.
But but Dell said, oh, wait🤤.
Dell won't understand this.
@@sexonlegs666
There are multiple videos of him at that time of day and temperature. Several of them with his own children and nephew flying those conditions as young as 12 years old.
You didn’t answer, just tried to turn it on me and add more accusations of Dell. Dell is plainly the man, not only does he say but he does. It doesn’t matter what I do or do not do. I’m not trying to insult Dell the way you did. Your lack of answer is all the answer I need. You don’t have the skills, Dell does. Post a video of yourself flying a reflex in those conditions. Until then you have no place to criticize.
Dell is a clown and very bad for the sport
Super job Ian. If I didn't know any better I would think you read the test results. Here is a link for the actual NASA test on the reflex design, I think back in 2003 or something. The test speak for themselves and rightly show ignorance in aerodynamic theory, especially surrounding reflex glider wings. ntrs.nasa.gov/api/citations/20040161133/downloads/20040161133.pdf