Hooknswoop

Ignorance is cure-able, stupidity is permanent. Derek

Right, the pilot perceives that a canopy dives longer on a windy day, but it doesn’t. Given the same input the canopy reacts exactly the same regardless if there is wind or not. The only difference is groundspeed. Derek

Ever gone by a toy balloon in free-fall or under canopy? Test of Toy Balloons Performed For Federal Department of Aviation Derek

I would try and limit the amount of sweat, etc that got on the canopy. Once the salt crystalizes, rinsing is the best way to get it out. Wiping it down may dissolve the salt but doesn't remove the dissolved salt from the fabric, so that once the fabric drys, the salt re-crystalizes. Completely rinsing a canopy is a time consuming process which also damages the canopy by increasing the porosity of the fabric. Wear a t-shirt when packing and maybe keep a towel nearby to wipe away sweat, etc as you go. Derek

Center cell from the bridle attachment point to the tail. Derek

An airspeed indicator works with a pitot tube and a static port. It compares the ram-air pressure coming into the pitot tube with ambient pressure from the static port to give airspeed. The ram-air pressure into the pitot tube begins immediately and increases with airspeed. The same thing with a canopy. It flys through the air and rams air into it, creating a higher pressure inside the canopy than outside the canopy. The low pressure (lifting force) is only above the canopy from the shape of the upper surface. One atmosphere is only 14.7 PSI. A few PSI is enough to make the canopy quite rigid, like a mylar helium balloon. Derek

Then explain how an airspeed indicator works at less than 40 mph.......... The air pressure inside a canopy is higher than the static air pressure near the canopy. Derek

LMAO!!!!! Derek

It is harder to stall with the higher airspeed, but will still stall. The problem with being lowin a dive is your reactions are to bury the toggles in order to pendulum back under the canopy before impacting the ground. Too much toggles also creates more "G" forces which raises the airspeed the canopy will stall at. There is a maximum recovery position of the toggles, not enough and it isn't recovering as fast as it could and too much and it isn't recovering as fast as it could. I think it is the round rushing up that can over ride what the pilot knows they should do and they pull too much toggle, stalling the canopy and 'mushing' into the ground. Ever see the video of the F-18 hitting the runway at the airshow? It is about 10-15 degrees nose up, descending into the runway as it hits. It stalled into the ground. Derek

My TX philosphy: TX reserves the right to leave the union. Fine, get out. We'll build a wall around TX and texans will need a passport to enter the U.S. We'll divide CA into NC and SC so we don't have to change the flag. Derek

[Quote]A cross braced 9-cell canopy does not have any advantage over cross braced canopies with respect to pulling out of a dive I meant a non cross braced canopy 9-cell canopy does not have any advantage over cross braced canopies with respect to pulling out of a dive. Typo. Cross braced canopies tend to have a longer recovery arc, but pull out of the dive better because they produce more lift and distort less than non-cross-braced canopies. I would rather be pulling out of a dive under a cross braced canopy than a non cross braced canopy, all others things being equal. From Icarus’s web page: “Bulge distortion is minimized to the point that the canopy is held so well into shape that any cross section of the canopy will show a maximum airfoil distortion of only 8.75% from the desired shape. (compared to 11.5% on 21 cell X-Braced designs and over 20% on conventional 9-cells).” Bulge distortion, or the amount the non load bearing ribs ‘rise’ relative to the loaded ribs and the amount the skin is allowed to bulge outward between ribs. With the extra rib per cell and the cross bracing, bulge distortion is reduced on tri-cell cross braced canopies. Nothing about “tail deflection”. The tail is deflected by the steering lines. You can pull the toggles farther down on a crss braced canopy without it stalling. Yanking the toggles too far will put the canopy into a stall by exceeding the critical angle of attack. The “G” forces produced by the maneuver. Stall speed increases to the square root of the load factor. For example with 4 “G’s”, you double the stall speed. Pulling down the toggles increases the lift and adds drag, both of which will return the canopy back over your head. Pulling them too far leads to an accelerated stall which will cause more altitude to be lost before the canopy is back overhead than having the toggles a bit higher and not stalling the canopy. The canopy doesn’t have to collapse for it to be stalled. Derek

--------------- Why would wind not affect a canopy in a steady state flight, but would affect it in a turn/dive? The wind hasn’t changed, it is still horizontal. It is the canopy’s attitude that has changed. It will not descend any faster if the air mass it happens to be flying through is moving over the ground or not. To clarify, you are saying wind does not affect a canopy in stead state flight, but it does affect a canopy that is turning hard? I don’t see the difference. The airspeed indicator reads zero regardless of the direction it is pointed. So if it changes attitude suddenly, there is still no wind acting on the helicopter. It is moving at the same speed as the air mass around it. There is no wind hitting the helicopter that would make the airspeed indicator read anything. Just because it changes attitudes does not change the fact that it is not moving relative to the air around it. Back to the fish bowl analogy. A fish in a bowl swims around at 1 mph. It can descend, rise, and swim around exactly the same regardless if the fish bowl is stationary relative to the ground, or if it is moving relative to the ground. Do you agree with this? Derek

Thanks, the FAA updated the document as of October 15, 2003. It is much better than it was. If anyone finds a broken link, something wrong, or smothing that has been updated or changed, let me know so I can fix it. Thanks! Derek

If it were true that a canopy descends more in a turn when there is wind, then it would descend lees if the maneuver was done the exact opposite, so that the canopy was landed downwind. This is not the case. If it were true that a canopy descends more in a turn when there is wind, then aircraft would descend and even climb faster (fpm) dependant on the wind, they don’t. Have you seen the video of the porter flying next to the free-flyer? The porter descends at the same rate, regardless of the wind, as it circles the free-flyer. A helicopter hovering next to a hot air balloon that is moving 20 mph over the ground will show zero airspeed, regardless of the direction it is pointed. Do you agree that wind has no affect on a canopy's airspeed? Derek

I use the terms 'flare turn' and 'flat turn' interchangably. Some may call a turn with rear risers flat a turn and a turn from half brakes a flare turn though. Kinda confusing. To clarify, step one after a too low turn is to stop turning. This stops things from getting worse. Step two, is to get the toggles to the maximum recovery position as quickly as possible to get back under the canopy as soon as posible. so wherever the toggles are at, regardles if one has to go up and the other down or both down, stop turning and put the toggles in the max recovery position as quickly as possible. Prepare to PLR and don't give up. Derek

Correct me if I am wrong, but can't a pre- A license student do solos w/o a Coach or Instructor after they are cleared to self-jumpmaster? Therein lies the crack they can fall through. Also, the ISP isn't mandatory. Derek

You are thinking in terms of relative to the ground and not relative to the air mass. First, define wind. Def n. a large body of air in rapid natural motion. Second, how do we measure wind? With a wind meter that is fixed, usually in mph or knots. This tells us how fast the air mass is moving in relation to the ground. Third, define airspeed, the speed at which a body moves through the air. Airspeed is irreverent of wind speed. An aircraft, glider, or canopy flys exactly the same regardless if the air mass it is flying through is moving across the ground or not. A perfect loop as viewed from a hot air balloon will look exactly the same to the observer in the basket in zero wind as it would in a 50 mph wind, because the balloon is staying at the same fixed point within the moving air mass, even though it is moving over the ground at 50 mph. To an observer on the ground, the loops would look different because the air mass is moving relative to the observer on the ground. The loops would be identical to the pilot of the aircraft. The wind doesn’t affect how the aircraft flys, lift vectors, or anything else, only its ground speed. Derek

Then how does the wind hit the top skin? If it hit the top skin in a dive, it would hit the nose if you were flying into it, slowing your airspeed, but it doesn’t. If it were true, an airplane would descend faster (fpm) with a head wind than wind a tail wind, all other things being equal. They don’t. Not true. If it hit the top skin, it would collapse your canopy. No it doesn’t, for the same reasons it doesn’t affect airspeed. No, it won’t, it will only affect your ground speed. It really doesn’t make a difference. Yes. I have jumped in very high winds and no wind. The wind never caused my canopy to dive more. Derek

All inputs with toggles. Rear risers will cause a stall faster than toggles. Similar to why an airplane will stall at a higher speed with no flaps, a canopy will stall at a higher speed on rear risers than on toggles. You may not realize that a canopy has stalled because stalling a canopy by burying the toggles after a low turn and slowly burying the toggles from full flight until it stalls feels completely different and the canopy reacts differently. Either way, the canopy is stalled and the recovery arc is longer than if it wasn't stalled, which means it will take more altitude to get back under the canopy. Derek

LOL, yep. It would be a good idea to double, then triple check that it is hooked up correctly. Derek

Of course not turning low is the best solution, but it does happen. “Be more careful packing” is not how to answer, “What do I do if I get a bag-lock?” “Cutaway and pull your reserve” is the answer. I haven’t seen low turn recovery techniques covered in first jump courses. I have seen (and taught) no low turns. I think the original poster was asking for himself and hoping that others may benefit from the answers as well. A fair question with some good answers. Derek

Not bad. The canopy may have a small built in turn if the toggles are not set far enough down the steering lines caused by the slight difference in length and pulling down the tail slightly unevenly. I prefer to either finger trap a loop and sew it, or use the ‘no-sew’ finger trap method for attaching toggles. I don’t like having knots which can hang up on the guide ring, or the excess line flapping about. Canopies come with links up, not including PC and D-0bag. Containers come with rises, toggles, D-bag and PC. Derek

Correct. If your canopy flys at 30-mph airspeed, then regardless if you are backing up over the ground or doing 65-mph, you’ll only feel 30-mph wind. Imagine if you are over a solid cloud layer, you wouldn’t know if you were backing up or zooming across the ground. You could only feel the 30-mph of wind, regardless of your ground speed. With only the cloud as a reference (and the air mass you are flying in) you could only sense your airspeed, not your ground speed. We determine wind direction by our drift over the ground. If we are going very fast, we have a tailwind, slow and we have a head wind, drifting sideways, a crosswind. We need the ground as a reference for determining our ground speed. Without it, we do not have enough information to determine which direction the mass of air we are flying in is moving over the ground. Derek

Huh? The amount of tail deflection is determined by how much the toggles are pulled down. A cross braced 9-cell canopy does not have any advantage over cross braced canopies with respect to pulling out of a dive. Given the same wing loading, a cross braced canopy will pull out of a dive without stalling better than a non-cross braced canopy. Pulling out of a dive with toggles adds “G” forces and increases the amount of lift the canopy is producing (and drag). This causes non-cross braced canopies to have their non-load bearing ribs rise in relation to the load bearing ribs. This causes a zigzag shape if viewed from the front of the canopy. This zigzagging causes the canopy’s span (wing tip to wing tip) distance to decrease, the top skin to distort, and the total effective surface area to decrease. This means less lift to pull out of a dive with. Derek

An emergency low turn should be a flat turn. Failing that, after a panic low turn, first stop the turn by matching the opposite toggle at about half brakes, not by letting up on the toggle that was used to initiate the turn, unless it was pulled down beyond half brakes. Half brakes is only a general position and the best amount to pull down the toggles varies from canopy to canopy, and by wing loading and how the toggles are set on the steering lines. The max recovery position should be practiced before hand. Be careful to avoid a stall, which will make the situation worse. A stall can happen at any airspeed. A canopy (or wing) stalls at a critical angle of attack, not an exact airspeed. I have seen a salvageable low turn result in an injury because the pilot pulled down too much toggle and stalled the canopy. At some point the turn is too low and unrecoverable before impact with the ground. There is no fixing it, only minimizing the damage by placing the toggles in the best recovery position and a PLR (Parachute Landing Roll). Derek