alberto1980

In Aviation they call it the drift towards failure. It is well known in aircraft maintenance. Even the FAA knows about it

When is next attempt? if you land it you are my superhero. Respect :)

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> Any canopy that successfully inflates can take air from very steep AOA's since that's where it comes from during opening.

Well the slider here plays a big role since it makes the canopy 'arch' a lot when it is up there close to the fabric (extreme camber during deployment, see attached pic) so this is not true and canopy collapse beyond stall angle of attack proves it. Note though, canopy stall is not related to its failure to get air through the nose. I am pretty sure that NOVA issue was in fact related to airfoil / planform shape or a combination of the two more than air intake design.

Great posts as always This is a really interesting thread.

PS everyone: DZ.com has a 'Check spelling' button, let's use it

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I think you need to be very clear in your definition of laminar and trubulent, Organized, uni-directional flow is not necessarily laminar. It can be highly turbulent.
Flow in a wind tunnel is wall-bounded. Even though it is organized and conditioned to be straight, it is still highly turbulent. It may be small scale turbulence, not visible to the naked eye, but still turbulent. Reynolds numbers for this flow are very large.
Flow over a skydiver in the clear blue sky will also be turbulent.
True laminar flow is actually very difficult to produce, even in a lab setting.
The burble above a skydiver is the region where the flow has separated. If you ever see a video of a bag lock malfunction, you will see the bag getting buffetted around abover the jumper. The bag is being pushed around by the vortices in the vortex street that is formed when the flow separates around the sides of the jumper.
It is also the reason why most ratty student jumpsuits are torn at the sides of the arms and legs. They are in the region where the flow separates and they whipped around in the vortices!
!

I am always in awe when realizing that aerodynamics is such a widespread and enjoyable hobby

Correct me if I am wrong but loaded above 1.4 or not, this is definitely a drawback of a partially open ram air canopy nose. if it collapses there's less intake area to restore its shape. On the other side there's also less intake area to let the air out. But what I really think is that the intake is designed to be at the stagnation point on the wing, and if you load it light this stagnation point is above it (flying at lower angle of attack), therefore the intake is less effective.

Best of luck man, this is great, I can't wait to know how this goes.

do you think those two little white loops hold your weight? 3 ring system = triple mechanical advantage

Hi I think it is pretty clear why beyond a certain optimum wing loading there is a performance penalty.
That's because every wing has an optimum glide ratio at a certain lift coefficient (see pdf attached). Let's say you are doing a distance competition. your speed is given by the trim angle of the canopy and your weight mainly. so you can imagine now to change the size of your canopy to get at the maximum glide ratio: you are now at the best loading for your wing in terms of aerodynamic efficiency. Load it more, performance degrades.
That is why an airline plane climbs higher and higher during a flight, to compensate the weight decrease with density decrease (and therefore fly at the same CL with different weights): they want to fly at the best efficiency, set speed and save gas.
if you take the same canopy now, let's say a vengeance and you plot the figure I sent for different sizes, the curves will shift to the right as you decrease the size (square feet of the canopy), therefore the best glide ratio will be at a slightly higher CL. This is because of Reynolds number effects: but remember the graph is for the drag coefficient! There will be also an optimum size for the minimum drag when the CD is multiplied by the area to obtain the drag. Decrease the size even more (at constant wing loading) and you decrease performance. So for a pure distance performance, there is an optimum wing loading and an optimum size.

LEGAL
leagle sounds like a french eagle

yes but you still have the mesh holding the pilot chute fabric right? well then wouldn't it inflate? A rigger please step in

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If the kill line AND apex support tapes ALL broke, then the P/C would indeed streamer.

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Could you please explain this?

I do not suggest you trying that, but giving in spin ailerons make the spin steeper and steeper until the aircraft gets out of the spin. personally tried on a pc21. I am not sure it works on a twin like an Otter though..

I think the only way to get out of a back spin without thinking too much about it, is to give 'in spin' ailerons and getting the spin steeper and steeper until the aircraft gets out naturally. From the video though the spin seems pretty steep, definetly not a flat one. that is also why they experienced hi g forces. there's another video like this with a Britten Norman Islander stalling and then going into a spin while on jump run. It's on youtube somewhere, but they recover the aircraft after a few turns .
If it was a certified aircraft, it would have gone through a stall characteristics certification, which includes spin demonstration unless an artificial stall is set with a stick pusher or something, but I do not think this is the case. That vertical tail is tiny, I am not surprised this happened. everybody seemed to walk away and for the aircraft who cares

I also had similar experiences with people from Caserta - Naples area in Itlay. A lot of scumbags. Maybe the sticky post on the gear classified should include Southern Italy as well as Nigeria for scam warning.
Sorry dude to hear this. Yeah ok now you can bash me because I am generalizing and this is not fair, since "I'm sure there also honest people from there". True, but that' s not the majority and this is a fact.

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I am an engineer.

I am really sorry for you dude

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So it doesn't flip over when you land in water silly.

Opie, the question was related to the fact that there are extra fins on the tail, I was asking why they put floats on the aircraft they use for parachuting. But I shouldn't spend more time to explain these subtle aerodynamic things, I mean you have lots of jumps so you probably know more than anybody else. It's always amazing to see how aerodynamics is such a widespread and enjoyable hobby

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WEIRD!! I jump out of those.

The Tail number is even correct. but the tail doesn't have the extra fins like the real ones do.

why they use floats sometimes on that plane?

I wouldn't seek advice on the internet for this, even if you find qualified people here. Just stick to what the experienced and qualified people you know (i.e. your instructors) suggest to you, and you will be fine.
Enjoy your skydives, have fun and be safe

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Because the big cargo door is structural, meaning it is an integral part of the airpfame and can't be removed for flight.

HW

Howardwhite won this. This is the exact reason. Although there is a (now shelved) project at Pilatus for a jump plane version featuring a doubler reinforced door to allow it opening in flight and a fixed landing gear.

It would seem like the perfect jump plane, single engine, T-tail, big CG envelope, big door. Why nobody operates it in the civil activity?

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Clean wings are MORE susceptible to flow separation. That's why you see VGs on 737s, 767s, learjets, and the White Knight II, all of which have very clean wings.

Everything you mention is transonic aircrafts. There VGs serve the purpose to reposition shock waves, but this is another story, I don't want to get into nerdy aerodynamic discussions here, just wondering about VGs and wingsuits, and LouDiamond gave me the answers. Thanks for the discussion guys.

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...few wingsuit arm wings are as aerodynamically clean as planes

That's why they may be beneficial. If a wing is superclean and well designed, no need for VGs

Ummm... no. I don't think you understand what VGs do.

Can you explain then?

Ok, so they did try already. So basically they were beneficial from wind tunnel tests but too sensitive to position/dimension, therefore not used anymore?

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...few wingsuit arm wings are as aerodynamically clean as planes

That's why they may be beneficial. If a wing is superclean and well designed, no need for VGs