Bucking hornet

[siujumper 0]

I jump a hornet (PISA) 150 and almost every time I grab the risors to do a hook turn the rear of the canopy starts to buck and seemingly loose pressurization. Everyone that I've talked to has said to lengthen the steering lines; which I have--about 5-6". It seems that when I grab the risor and start the dive fast there doesn't appear to be that problem, but when I grab the risor and gradually apply pressure to build up speed (carving more than swinging) the faster I start to go, the more the canopy gives me problems. It's just not smooth and I'm afriad that one of these times it will either collapse or loose altitude way more rapidly than what I am prepared for. Comments? blue skies

[PhreeZone 19]

How much slack is there in your break lines in full flight? If there is not 6 inches or more you will probally need to lengthen your breaks some more. Loan your canopy to a more experienced swooper and get their opinion too.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[Hooknswoop 19]

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but when I grab the risor and gradually apply pressure to build up speed (carving more than swinging) the faster I start to go, the more the canopy gives me problems.

The faster you fly, the more drag there is on your steering lines, bowing them back and pulling down the tail.

Try this: Clear your airspace at altitude, without the toggles in your hands, do a full 360 with the front riser(s). If the canopy doesn't buck, then your steering lines are too short. Try another full 360 turn with the front riser and with the toggles in your hands. If the riser pressure is higher, then your steering lines are too short.

If you can't completely flare your canopy, then your steering lines are too long. If you find that you have to lengthen your steering lines beyond where you can completely flare the canopy to prevent it from bucking in front riser turns, longer risers is the only 'fix'.

"How to Adjust Steering Line Length for Optimal Performance"

The length of the steering lines can drastically affect how a canopy flies. High performance canopies are affected much more than lower performance canopies. All canopies should have some slack or a slight bow in the steering lines. If the steering lines are too short and pull down the tail of the canopy during full flight, even slightly, the canopy is flying in brakes. If the canopy is flying in brakes, it will not have as much speed to trade for lift during the landing flare. Over time the steering lines shrink as a result of friction from the slider during opening, as much as 6 inches in extreme cases. New canopies or line sets adjusted to have no slack in the steering lines will begin to fly in brakes as the control lines shrink.

To maximize the performance of your canopy it is necessary to understand the construction of the steering lines. The steering lines on a canopy are made of several parts. The upper control lines, usually four or five lines cascade or split at the top of the central control line and attach to the tail. The central control line attaches the upper control lines to the lower control line. The lower control line attaches from the finger-trapped loop (for setting the brakes) at the bottom of the central control line to the toggle. The lower control line is where your rigger can make adjustments.

If you do not use your front risers, adjusting steering line length is a fairly simple process. To check your control lines, pull one toggle down an inch or two while watching the tail of the canopy in flight. The tail should not move and the canopy should not turn. If it does, your lower steering lines need to be lengthened. Make small adjustments, no more than an inch at a time. This may require several adjustments. It is better to be an inch too long than an inch too short. Once you find the correct length, have your rigger finger-trap and bar-tack the lower steering line to eliminate the knot next to the toggle which can hang up on the guide ring. Periodically check the steering lines to see if they have shrunk and need to be lengthened again. Micro-line can shrink 4 to 6 inches or more over its life span. Vectran tends not to shrink with wear but is not as durable as Micro-line.

If you use your front risers, adjusting steering line length is more complicated. Having enough slack in the lower steering lines on a high performance canopy is more critical to how the canopy will fly. In a front riser turn you are pulling the toggle down a little with the riser and there has to be some slack to prevent pulling down the tail. If the tail of a high performance canopy is pulled down even a little when front risering, the riser pressure will be much higher and the recovery arc (the amount of altitude required to get back under the canopy) will be shortened. To check if the steering line is long enough, clear your airspace, do a full 360 degree front riser turn (keeping the toggles in your hands), and watch the tail of the canopy. As the speed increases, the drag on the control line increases and if there isn’t enough slack, the tail will be pulled down. You need enough slack so that the tail won’t be pulled down while pulling the toggle and the riser down at the maximum speed of the canopy. Again, make small adjustments no more than an inch at a time and have your rigger finger-trap and bar-tack the lower control line once you have them adjusted correctly.

With the steering lines correctly set, your canopy will dive longer and faster and you can get the most out of your canopy.

Derek

[siujumper 0]

There is quite a bit of slack in full flight. I think that the next time I jump I'll do the 360 deg. hook at altitude w/out toggles to see how that works. If it still bucks I'll do two things: 1) loan it to an experienced swooper and 2) lengthen them more if needed. Thanx for your reply.

blue skies,

siujumper

[monkeyKam 0]

For those airfoil techno-geeks out there, the statement below should be corrected (I just wanted to be sure that the actual physics of the system were properly understood):

> The faster you fly,
> the more drag there is on your steering lines,...
> bowing them back and pulling down the tail.

First of all, the drag on the lines is not at all greater than that of the drag on the bottom of the tail of your canopy, therefore, the lines cannot pull the tail down.

More than that, the direction of the relative wind striking the control lines (and the whole parachute system, for that matter) is more upward relative to the bottom surface of the canopy (due to the nose-down trim of the airfoil). If it were even possible that the lines had more drag than the bottom surface of the tail, the vector of the drag on the lines would need to be downward in order to pull the tail downward, which it is not (see attached diagram).

If the tail is being pulled down during static or clean flight (no inputs), there is something mechanical at work, not something relating to drag. That is to say, something is pulling the control lines and it isn't drag.

Sorry for the goofy diagram, but it definitely helps illustrate the point.

Andy
andy@bigairsportz.com

"I drank what?" --Sophocles

[Hooknswoop 19]

If there is just enough slack in the steering lines that when the front risers are pulled down, there is no slack remaining in the steering lines and the steering line will be taut at the initiation of a front riser turn/dive. As the canopy accelerates, the drag on the steering lines will increase and pull against the toggle and the tail of the canopy. This drag is transmitted to the toggles, and the tail. The jumper feels this force as an increase in front riser pressure, even though the pressure on the front risers has not increased. Since the jumper is holding the toggle, the tail will be pulled down a little and the perceived front riser pressure will be higher.

This causes the canopies maximum speed to be lower, the recovery arc to be shorter and possibly, for the canopy to 'buck'. The only fix is to lengthen to lower (brake setting to toggle) control line. This puts more slack in the lines, preventing the tension at the tail and toggles.

It is possible that in order to have enough slack in the steering lines to prevent the tail from being pulled down, the jumper will not be able to completely flare the canopy. Longer risers, which moves the canopy further away, is the solution to this problem.

Your diagram is representive of normal, steady state flight, but not a front riser dive. When there is just enough slack to allow the front riser to be pulled down without pulling down the tail, there isn't enough for a maximum speed front riser dive because of the drag on the steering lines.

Edited for better explanation and pic.

Derek

[Blahr 0]

I recall reading a post or two that suggested that the Hornet will buck when using front risers.

[siujumper 0]

Were they bucking even when the steering lines were lengthened? Is it a design flaw of the hornet itself?

blue skies

[sammer 0]

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Were they bucking even when the steering lines were lengthened? Is it a design flaw of the hornet itself?

It does seem to be a commonly reported problem among Hornet owners. There have been several posts here regarding "bucking Hornets", and I think that most of them have happy endings after the owners got the brake lines lengthened. From what I have gathered, the Hornets just usually come with brake lines that are too short.

I was having the same problem with mine and it required both lengthening the lines and getting longer risers. I have not flown very many different canopies, but it seems to me that the control range is a bit longer on the Hornet (it's really hard for me to stall it). So just lengthening the brake lines without getting longer risers didn't seem to be prudent.

Hope that helps,
Sam

[bmcd308 0]

I have a Hornet 190. I am 6'6" tall, so I have very long risers compared to most folks. My brake lines are a good 6 inches longer than the black dot that came on the brake lines would suggest, and I am very happy with that setup. I can get a full flare (and can collapse my canopy up high if I want), and I really do not get a whole lot of bucking in front risers (although I still do get some).

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www.jumpelvis.com

[VectorBoy 0]

As the canopy accelerates, the drag on the steering lines will increase and pull against the toggle and the tail of the canopy. This drag is transmitted to the toggles, and the tail. The jumper feels this force as an increase in front riser pressure, even though the pressure on the front risers has not increased. Since the jumper is holding the toggle, the tail will be pulled down a little and the perceived front riser pressure will be higher.

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So are you saying that in a front riser ( or any banked manuever ) dive the that the front riser pressure does not increase? Or just that in the case of short brake line / bucking canopy the increase is abnormaly high?

• Quote

[Hooknswoop 19]

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As the canopy accelerates, the drag on the steering lines will increase and pull against the toggle and the tail of the canopy. This drag is transmitted to the toggles, and the tail. The jumper feels this force as an increase in front riser pressure, even though the pressure on the front risers has not increased. Since the jumper is holding the toggle, the tail will be pulled down a little and the perceived front riser pressure will be higher.

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So are you saying that in a front riser ( or any banked manuever ) dive the that the front riser pressure does not increase? Or just that in the case of short brake line / bucking canopy the increase is abnormaly high?

Front riser pressure does increase in a front riser turn/dive. Too short of steering lines adds to the perceived front riser pressure. The steering line(s) pull on the toggle, in the jumper's hand(s), at the same time they have the front riser(s) in their hand(s). The steering lines should not pull on the toggles or tail during a frint riser turn/dive. If they do, they are too short. So, I am saying; " in the case of short brake line / bucking canopy the increase is abnormaly high?"

Hold a piece of string between your hands and pull it tight. Have someone push on the string and the string will transmit that pressure to both of your hands, even if the direction of the force applied isn't 90-degrees to the string.

Derek

[ChileRelleno 0]

You may be applying enough excessive frontriser input to stairstep the nose and interrupting the airflow over your canopy, hence the bucking.
Just as easily it could be the brakeline setting, I fly the Hornet and have had to adjust (lengthen) them.

ChileRelleno-Rodriguez Bro#414
Hellfish#511,MuffBro#3532,AnvilBro#9, D24868