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as a side note...what are the two most popular (useful ) sizes of pilot chutes to have? I currently have a 42" and will be adding another with my new rig purchase. Thanx.

What do YOU preffere to jump/jump most?
my 2 most popular pc´s are 42 and 46

I've split this off from the "Drag Table" thread, a it appears to be a separate, and useful, discussion.

When I was learning to BASE jump, my mentor said something like this:

You will need three PC's:

1) Really big one, for low stuff.
2) Small one, for terminal stuff.
3) A 42", for everything else.

Which is more important (very big or very small) is going to be for you to decide, based on what you plan on jumping.

If you are planning on doing big stuff (terminal towers, or a big wall trip to Norway, or something similar), get a smallish PC. My two favorite small PC's are the BR 36" F-111, and the CR 32" A/V. In terms of deployment characteristics (primarily orbiting and oscillation), I slightly prefer the F-111. But the ZP on the A/V will last far longer (two or three times as many jumps). If you are planning on keeping it forever (i.e. several hundred terminal jumps), I'd go with the CR 32" A/V. If you are only going to do a few terminal jumps a year, I'd go with the BR 36" F-111.

If you are going to be doing low stuff close to home, you'll want to get a big PC next. My favorite big hand held PC is the BR 48" ZP. I prefer it because it has nothing on the apex, yielding less potential for hesitation and overall faster and more consistent inflation.

you prefer no vents tom for really low stuff and for everything else vents? I thought vents sacrificed a little speed in the deployment but much less oscilliation? I remember reading on here something about a vented PC will have a smaller margin of error than a nonvented PC. Such as a nonvented PC might deploy much faster one time but much slower the next whereas a vented PC is much more stabile. Isn't this stability would be what you are shooting for doing low low stuff? What do you think about that?

Thanks (sorry if I asked you a million questions at once ).

It depends on your definition of "really low". I'd prefer an unvented PC for some very low stuff that required specialized techniques. I'd prefer a small vent (like the BR 48 vented PC's that DW had, I'm not sure if they'll sell them to mere mortals like me, though) for the "general purpose" ultra lows in the 180-220 range.

However, given a choice between the everyone else's vented 46's and BR's unvented 48 (the choice most of us are faced with), I'd probably go with BR's unvented 48.


True.


I think you misremember. That discussion was about hand held v. stowed PC's. rather than vented v. unvented. The vented v. unvented difference (in terms of reliability) is pretty marginal, but probably falls (slightly) in favor of the unvented PC.


Are you asking about stability of the PC, or reliability of inflation times (i.e. resistance to random hesitations)? These are two different things, with vented (or F111) PC's being far better at the former, but marginally (or more in the case of F111) worse at the latter.

Does canopy size have any relationship to PC size? For instance, say jumping an ACE 310 or equivalent...would that put me into a bigger PC range?

Yes, but...

I've seen the max size canopies jumped with undersized (by delay) PC's, with no ill results.

The only times when I would really worry about upsizing the PC to match a big canopy is on an ultra low jump (200' or less), or a low pull (loosely defined as more time in freefall than under canopy).

Some guys I spoke to said for real low stuff they use a 52", ain't that a bit too big????

Who makes 52" pcs now anyway?

i guess it rely on the person.

I freefall 180ft whith a 46´zp av pc from CR,which does the job werry well.

Other groups of Europaeans(The hardcore Belgiancrew) freefall 150ft whith a 46´zp pc,and smoke 42´zp pc down to 180ft freefalls.. i think some of their 150ft freefalls are at their site.I dunno if they post here but if they do,they might answer this...

I tried to ask this (sort of?!?!) in another thread about the drag differences and opening distances with different PC's - but no one responded................. then I decided to look into this myself with 689's handy XL spreadsheet..... thanks 689!

http://www.dropzone.com/...i?post=729814#729814



Be safe always.............

well I won't be worried about doing anything near 200' anytime in the foreseeable future...thanx for the info.

i never saw a 52´ but i saw a 48 and that is one BIG pc

In general, yes. DW used to use a 52 for his super low jumps, but it was a custom made 52 with almost no weight on the topskin.


I think that you'd have to get a 52 built custom, currently. Gravity Sports Limited used to make them as a stock size, but they had a cap on the apex, which I wouldn't recommend.

whats the function of the cap then? What was their reasoning for having one? What's your reasoning for not wanting to jump a PC that big with a cap on the end? Adds unnessecary weight to the PC - slows down inflation?

The cap is intended as a handle to facilitate easier "grabbing" of the PC when stowed. It was developed as an alternative to PVC and hacky handles, which are not safe to use on a hand held PC. The cap is a sort of happy medium, which is meant to allow the PC to be used hand held or stowed.

Any additional weight on the top of the PC will slow down (and make less consistent) the inflation.

I've recently decided that this is a bigger deal than we all previously thought, after discussions with a friend, and review of the photos on this thread. If that PC is sideways at terminal, imagine how much effect the weight of the handle will have at 6 seconds.

ok now Im confused, tom.

Who is going stowed on a jump that requires a 52" PC!?!?

Hey Tom

Just to add a little to the big PC debate....

I've got a custom made 52" (true diameter measurement) ZP no-cap, unvented PC which I have only used ONCE.

It was TOO big!!!!

[245 Fox 'vented only' v-tec, 0.70 wingloading, single bridle attachment.]

It created so much drag it impeded inflation and did not allow for full flight. I had very little forward speed and a whole lot downwards. I hit the ground very hard with what felt like 'half' a canopy over my head.

For low stuff I've stuck with a BR 48" ZP (46" true diameter) with good success.

I was thinking I could still use the big 52" PC for low freefalls with a roundie into H2O. I don't think it would affect flight characteristics. Any thoughts?

Does that follow? Would any pilot chute really inflate at anything short of bridle stretch? Seems like until there is some sort of pull at the bridle attachment point, a pilot chute is just a floppy bit of fabric.

Now, at your 6 seconds, I probably would want the pilot chute to follow me as little as possible, so reducing the weight of the thing (for a given size) as much as safely possible is, I'm sure, an excellent plan.

I'm just saying that the orientation of it prior to bridle stretch is probably a bit uncertain in any case. In the pictures to which you refer, it seems to me like the bridle and pilot chute are just dancing limply together in the the jumper's burble (until bridle-stretch).

Someone doing a double gainer.

Which, in practice, means pretty much no one.

I disagree. I believe that a ZP PC will begin to inflate as soon as it leaves your hand. It will be at least partly inflated well before it reaches bridle stretch.

An F-111 PC, on the other hand, will generally inflate at bridle stretch. This is the reason for the "popping" sound that you hear when an F-111 PC hits bridle stretch. It's doing all of it's inflating right then. ZP, of course, doesn't do this.

If you take an F-111 PC on a load with people who've only used ZP PC's, you can almost always freak them out. "What was that noise your PC made? Is it ok? It didn't tear, did it?"

I know this is super old but I thought I'd wake it up instead of starting a new thread. Plus i had to sift through 185 threads about pc sizes to find it, so I didn't wanna waste it.

Similar thing happened to me recently. I was on my Troll 205 loaded at .6 using a 48. I got dumped so hard it felt like I had no canopy over my head at all. The impact was hard enough to snap my tib/fib in half. I know this isn't an issue for most of you guys. But has anyone else on a smaller canopy had sketchy landings with a large pc?

I hate to blast my fuckup on this forum. But maybe someone jumping a smaller canopy can learn from my mistake

Sorry you got hurt Em

Did you have on any boots?
Knee pads? Attempt a PLF?

We all fuck up... so I am not
busting your balls, just curious.

Were you on a Low Exit ? - with 205 & 48" PC

If your exit height was pretty low . The PC might not have had anything to do with it . ( Even Though ) a 48" on a 205 'will' give you shitty Flair on the landing if you are not ready for it .
I have got dumped on landings when I exited Low & using a 48" on larger canopies than 205 .
real Low jumps & Exiting Into the Head-wind . But had a off heading 90 deg. on opening . & the Headwind is now working against you in helping your inflation quality on your Canopy.
Your Canopy time on Low exits is small till Flair & landing . & you got No time to get turned into the headwind on Landing . So the off heading, with side-wind that is now hitting you . It robs you of inflation quality before you land & you get a top-skin inflation but Not good full canopy inflation . So when you give input & Flair for landing . Your Canopy feels like its does not even know your the Pilot underneath it . & does not respond & you get 'Dumped Hard' .
.

It's my understanding that Emmy had full inflation and full flight, and that the problem happened during the flare. Emmy, is that right?

It's possible to put a PC on so big that it acts as an air anchor and slows the canopy enough that even the start of a flare stroke will stall it, but it's pretty rare.

Most of the time that I see someone blaming a big PC for a flight/flare issue it's really something else going on (like low opening and incomplete pressurization, or an uncleared brake) but the jump is happening fast, or at night, or with no video, so the explanations become a bit speculative.

Yes that's right. I'm 100% positive both brakes were cleared. And there was adequate time for full pressurization.

You're absolutely right, the pc issue is pure speculation and I may very well be wrong. The only other sketchy landing I've had was the only other time I used this pc, but that landing was in shin deep rain water.

I can't think of why else I would've had a hypersensitive stall point. But that's another reason I'm posting here. It did happen fast, at night, and unfortunately there is no video. I'll be at the bridge again in a few weeks. I'm tempted to make a jump with the pc and let you film it Tom if you're available. I'd really like to analyze possible distortion and flight characteristics in daylight.

Thanks Tom.. And it's cool. Maybe I deserve some ball busting. I don't really care about that. I obviously did something wrong.

No I didn't have on boots. Boom! Another fuckup. I was wearing a pair of Coach thin flexi shoes similar to climbing shoes. And I've been scolded before for wearing them. But I prefer to wear them on As because they make it easy to scale access fencing and feel more stable moving around on a tower.

Maybe boots would've helped, maybe they wouldn't. I'll be wearing them from now on regardless.

I did have a 110 offheading on this jump. It was a little low but not sketchy low, from 300. Low enough to make me feel more comfortable with a 48.

Are you jumping a 205 troll? what do you weigh geared up?

On a Hop-Pop 300' is plenty high to have 110 off heading & correct heading for landing .
You were Not turning when landing ?
If you were setting-up & landing on a strait-in approach on your Flair .
Were you landing into a Headwind ? . if so, how brisk was it ?
.

I wear boots on almost every jump!!!

Combat boots for low key antenna jumps
with landings into a soft plowed field and
Hanwags for Urban. Recently did ITW in
a pair of $25 Dr. Scholl's from Wal*mart
because the Hanwags were too heavy.

Pad up, Pound In.
Good Advice from Dwain Weston

post script
I got a bunch of extra body protection
for sale: boots, knee pads, spine, etc.
send me a PM if any one is interested.

Boots and harware only go so far.
It would have been nicer but hard to say it would have got you any farther with the pounding . To do your Tib & Fib you had to have just plowed-in below the deck .

Your looking @ . Pilot putting all the impact force on 1 leg on the landing with a ( Hook-Turn ) (no Flair ), Screaming fast Down-Wind landing with your 205 & 200 lb. pilot . Or other Pilot Error like Over Flair & Complete Canopy Stall high above the Deck . Or Canopy collapse during flair either induced by Pilot or enhanced by combination of pilot & other source of influence . Or all the above with the LZ being Asphalt or Concrete surface . Or something else ?

You need to elaborate more of an explanation of what you did . More Facts ????
Are you saying that you were on a perfect landing approach into a nice headwind on a soft grassy field & Flared perfect only to have your canopy just collapse a few Ft. above the deck ?
.

Under the right circumstances all healthy bones in the body, other than the skull, can fracture under 75lbs concurrent lateral pressure. Doesn't take much, man.

He even says >
..." Maybe boots would've helped, maybe they wouldn't ".

He needs to give better Info & about only useful info given so far .
-
300 Ft. tower hop-pop . 205 canopy . 48" PC
..." I got dumped so hard it felt like I had no canopy over my head at all ".
..." The only other sketchy landing I've had was the only other time I used this pc ".
..." I can't think of why else I would've had a hypersensitive stall point. But that's another reason I'm posting here ".
.

also Reason I was asking about the Headwind Landing earlier . If was landing in a nice headwind it would have added even more drag . Drag/pull with 48" PC does really pull & distort the center cell on a small canopy like 205 . It affect Flair .The 48" distortion with drag on Center Cell also has a relationship with the inboard A-B w/Trim and flight on a small 205 canopy .
.

She Ray, she

In a nutshell, here's the jump: Hop'n pop from 300, 110 off corrected on rears, 90 deg flat turn right, full flight, start to flare, drop. The offheading is irrelevant to the accident, I had adequate canopy time. Didn't hook in. No radical input. Just a dump.

And I doubt boots would've prevented the break on this landing. There was no tuck and roll, I didn't have any forward speed.

I've called it shitty canopy piloting from day one because I can't draw any specific conclusion about how or why it happened. Oversized pc is the only plausible theory I can come up with. But if it's as rare as Tom says then perhaps it wasn't that at all. If it wasn't, well then it was shitty canopy piloting.

Can you give us an idea of the elapsed time between these?

How much time between the rear riser correction and the flat turn?

I assume the flat turn was on toggles?

Did you pop the toggles in there? When? And how much time between the toggle pop and the flare?

How long were you in full flight?


My initial suspicion is that your canopy wasn't fully pressurized at the point that you flared, but if you had real full flight (not just toggles all the way up) before the flare, that's probably not the case.

not saying you were doing a shitty pilot job . but there was just a lack of info .

I say the 48" PC is the main culprit & that combined with your usual/normal piloting mechanics is what dumped you .
Your usual piloting mechanics does the job on the 205 but with that 48" pulling on the small 205 & (you not aware) that it is totally changing flight & Flair & Usual Pendulum on the landing .
I am also guessing your are a lighter of weight pilot also . That is the reason for the small BASE canopy .

I have watched . & once you stand-off to the side & watch a big PC towed behind a little canopy it all becomes pretty clear how it is ripping on the Center of bridal connection all the way to the Nose . The center & Nose are directly tied with the inboard A-B also .
Watch a Landing & also how the person Flairs & what the canopy looks like .
.

weight? troll 205?

I'm glad I jump a 280. With a 46 or a 48 on it all the time and cant tell any difference. I'm usually landing in no wind or a tail wind though.

Its been a while, but my account from above...
Exit (307' exactly)
go n throw... off heading instant correction (less that .5 seconds. flew straight out away from tower for 3-4 seconds... started flat turn.. I jump... 1 sec delay... open. fly straight and as I turn 180 hear a yelp (her landing)... from my perspective she was all fine and I thought the yelp was a quick "yahoo"... I was not watching so I did not see the exact landing, but she had plenty of time to get to full flight before landing.

She is small and at .6 wing load or less...

there was minimal wind on landing, so into/cross/down wind would not have effected the canopy or landing speed much.

She was high enough when starting the turn, that she did not "hook in" unless she did a 450 (which she did not).

all the "how many seconds was it before you popped toggles and how far did you pull them down, how many seconds did you fly before tunring, was it a 7 degree turn, 9 degree turn, etc... "there is no way to know without video, and really doesnt matter... she was in full flight with a fully pressurized canopy, flared and crashed... It was either pilot error for stalling it, or in the first place for having a PC too big for a small canopy with a small wing load.

There isnt much talk of how a large PC effects a small canopy with a light wingload... this mainly is in question. She is bringing it back up to say this may be an issue to address/be aware of...

If there was 3-4 seconds after the turn and before the landing (which it sounds like is the case from your account), then I think the PC was the most likely culprit.

Wing loading was .6? That's very low for a small canopy.

its a troll (205 = about 220)

Correct me if I am wrong, but once a canopy is in full flight the head wind or down wind shouldnt matter for airspeed of flight, right? flying into the wind or down wind will only change the ground speed, not the canopy air speed or flight...?

You are correct.

That is the Headwind that the canopy is flying against . I am talking about dragging a PC into a Headwind .

When PC being in-Tow & dragged behind the canopy in Flight . It take more pull energy to drag a PC into Headwind that it takes with No Headwind .
I am saying that flying the 205 into a Headwind with the 48" PC will add even more Canopy distortion with it dragging in-flight against the pushing winds energy .
.

Are you sure? If the windspeed is the same no matter what(which it is for >3 seconds of canopy flight), then the distortion will be the same no matter what.

no, i agree with Ray.

the PC is acting independently of the canopy. therefore if the canopy is in a zero forward speed sink, in a headwind, the PC causes drag. in a tailwind it will fall into the direction of flight, or create less drag.

Em. you need to use a smaller PC,
wearing boots/knee pads might help,
and once you are fully healed maybe
practice your PLF's.

PC selection should include not just the
object height and intended delay but
also be nudged up or down depending
on the jumper's size and canopy size.

For example: an un-vented 42" is fine
for an ACE240 from 300' but my 285
with vents needs a 48" on same jump.

see, that's where you're a bit contradicting.

there is no bottom line. each jump must be assessed by the jumper. comfort zone is a huge factor.

she doesn't necessarily need a smaller PC, just has to make sure she is comfortable flying with it. i agree it is overkill to have a 48" PC on a 205, but in the same regards, i would tell you that a 42" works very well on a 285 (down to 250' freefalls) as well. everyone's mileage varies, and there are a lot of variables on any object.

if the canopy has an airspeed of 10 mph... the PC has the same airspeed (its connected)... and should have the same drag in a head wind or tail wind. the only time this would change is with a gust from behind, hitting the PC before it hit the trailing edge of the canopy (then "pushing" the PC toward the canopy) or vise versa pushing the canopy back toward the PC.

the PC has the same drag on the canopy itself regarldess a direct head or tail wind.

If I was flying a straight in approach (not crabbing) in a direct crosswind, would the PC be behind me, or blown over to the end cell of my canopy? It would be behind me... because my airspeed stays the same... my travel over the ground would be a diagonal.

except when you're landing.

The canopy has no awareness of the ground. The canopy's behavior is not influenced in any way by the ground (keeping in mind that turbulence is not the ground, it is an artifact of the air passing over the ground). The canopy, and the attached pilot chute, fly through the air mass without regard to how that air mass might be moving itself (save for the aforementioned turbulence).

When it comes time to flare the parachute, the parachute still does not care whatsoever about the ground. The parachute only "knows" that its airfoil has been perturbed in such a way as to cause increased drag at the tail. In response, the canopy slows down. While the canopy slows down, its pilot continues moving unabated (for a while) due to inertia/momentum. This movement of the pilot below the canopy causes the canopy to change pitch/AOA, producing what we call the flare.

If the canopy is dragging a big-ass pilot chute, its air speed in full flight will be lower than when dragging a small-ass pilot chute. Thus, when the pilot flares, perturbing the canopy, the canopy won't slow as dramatically, and the pilot below it won't have as much momentum/inertia to continue forward as dramatically, either. Thus, the change in pitch/AOA won't be as dramatic, producing a less effective flare.

Additionally, because lift is directly proportional to air speed, dragging the big-ass pilot chute means the canopy produces less lift than usual to begin with and flares less dramatically to end.

Notice that all of this happens with complete indifference to the ground. The ground is only a factor to the pilot, who when dragging a big-ass pilot chute, is under a wing with less lift and won't have as effective a flare. The result can be a harder-than-expected landing.

ok, i pose some other questions:

if you are in a full brake approach (sink or flare) and are now essentially dropping straight down, what does the PC do in each potential prevailing winds scenario (i.e. headwind, tailwind, crosswind)?

does it change, or does it always follow the canopy, full of air, because it is being towed by the canopy (which is indifferent to the prevailing wind while flying)?


does a big vs. small PC change the effectiveness of "sinking it in"?

how about a "sink & surge" landing technique?

If the brakes are drawn and held, such that the canopy has no airspeed, yet remains inflated, as it begins to settle into its sink the pilot chute wil assume a position directly above the canopy. This would happen regardless of prevailing conditions - head wind, tail wind, cross wind - because those prevailing conditions are only relevant to us and the object with which we're measuring them relative to. The canopy does all of its flying within the airmass, wherever it may roam.

Often, when we believe we are flying our canopy in a full sink, we are only doing so with respect to the ground. The canopy actually maintains some forward airspeed. And in this case, the pilot chute will remain behind the canopy.

Conduct a little thought experiment based on experience from skydiving. We often skyjump in winds that are higher than those we BASE jump in. When flying our skydiving canopies far above the ground, on high-wind days, we turn this way and we turn that way. We fly in circles sometimes. And as we do so, the pilot chute is always following the canopy. Even if the winds are pretty brisk, and I make a 360 turn to the left, the pilot chute is not going to orbit the canopy in the opposite direction as it weather vanes in the prevailing winds, because those prevailing winds aren't "sensed" by the canopy or the pilot chute; they're only known to us, and relevant to us, because we have to land on something fixed - the ground.


Yes. But this is a bit more complicated. Let's say for the sake of simplification that we're talking about one canopy at one wing loading, and we are performing our sink with the brakes drawn the same amount regardless of the size of the pilot chute. In this case, as the pilot chute increases in size, the canopy will sink more dramatically because airspeed/attitude is negatively affected by bigger pilot chutes. In fact, the sink will become scary-violent if we continue this experiment.

If we fly smart and realize we have to ease up on the brakes to do safe sinking with bigger pilot chutes, we still need to realize that bigger pilot chutes will distort our canopies more, and possibly degrade the wing's ability to fly at low airspeeds.

So if we go back to the original set of questions that started this thread bump, we know we had a lightweight ninja jumping a small, lightly loaded canopy. So she had lower than usual canopy pressurization as a result of lower than usual airspeed. And she was dragging a 48" PC. That PC slowed the canopy down even more, reducing its pressurization even more, and is likely to have distorted her airfoil much more than the airfoils of we heavyweight ninjas who are loaded closer to .75.

So it's safe to say she would have experienced highly degraded sink and/or flare performance.


Even when sinking and surging, the canopy remains unaware of the presence of the ground or the way the air passes over it. The pilot chute will follow the canopy as usual, with one exception: the canopy and the PC will have their own momentum/inertia, based on mass, velocity, and surface area (surface area is relevant only because the PC and canopy don't have the same ratio of surface area to mass). Therefore, it's safe to say the tension on the bridle between the PC and the canopy will change some during transitions between full flight, sink, and surge. But the tension will settle out once a flight condition is established and maintained.

...

are you sure?

i disagree.

Most of what you say makes sense, but I'm not sure about this:


I question that because Lightning CRW canopies have been de-tuned so that applying brakes does NOT provide lift. It slows their airspeed down without changing their angle of attack very much, if at all. The pilot doesn't continue moving forward due to inertia. Their landings are almost always crappy (no matter if they are old or new, IMHO), but they are great CRW canopies because of the fact that applying brakes only slows the approach speed.

Apologies for being a bit off topic, but I'm finding this is an interesting thread, with interesting scenarios

Applying brakes does provide lift, just not very much/as much as one would expect from a "regular" canopy. One common beginner mistake in CRW is to use toggles alone on final approach to slow the canopy down, get lift, wrap your buddy from below.

I've been told that lightnings fly with a higher-than-normal AoA because of the line trim (shallow in reference to the ground). This should provide less lift when flaring. More added speed, more potential lift. I like this explanation because it fits with my own observations. Try approaching a formation with fronts and give some toggle input when you let go. You'll get lift (a lot of lift). Also, try adding speed for landings, they will get a lot better. Of course, letting go of the fronts will also convert speed to lift, so it might be an additive effect.

As to the questioned statement itself, I don't know. I just thought I'd add some observations on lightnings and the way they fly.

I would venture to say there's a left to right cross wind and the pilot is holding down more left toggle than right, because the pilot is concerned about the ground. This would result in the observed behavior of the pilot chute. Or, what you're seeing is the momentary change in bridle tension I mentioned between the PC and canopy as the canopy changes flight configurations. Once that dynamic moment is over, the pilot chute will take up its dutiful position behind the canopy's line of flight.

Also, if the pilot chute ever enters the burble of the canopy, its behavior will change until it leaves the burble.

But one thing remains quite certain, you can't say the canopy responds to prevailing air movement but the pilot chute doesn't, and you can't say the pilot chute responds to prevailing air movement but the canopy doesn't. Both are moving through the same air mass. If you're landing into a head wind whilst towing a big-ass pilot chute, that head wind is relevant for both the canopy and pilot chute. If you're landing with a tail wind, that tail wind is relevant for both the canopy and the pilot chute. Your argument would require that the wind be able to "blow" one without "blowing" the other. And that can't happen except for when the PC loses its 'thrust' because the canopy towing it has suddenly changed its flight configuration. And that change is momentary.

We can run the same thought experiments on a boat towing a sonar buoy. If the boat is driving cross-stream and maintains tension on the towing cable, the buoy will be behind the boat (perhaps slightly downstream due to its profile surface area). But the buoy is not going to be riding alongside the boat on its downstream side. If the boat slows down to the point that it is simply drifting with the water, not moving through it, then tension on the cable would be lost and the buoy would take up a position relative to the boat based only on its difference in mass/surface area profile relative to the boat.

Does that make sense?

In any case, our senses will try quite hard to tell us this stuff isn't true. We've all seen a bird apparently hovering in mid air, not moving at all. And at first it positively screws with our minds. But we realize the bird is gliding on a moving air mass. But at first our brains freak out, because we are terrestrial beings, and our senses are tuned to interpret all things relative to the ground.


Edited because I said something about a "toying" cable, which sounds like a sex toy. I meant "towing" cable, which is not a sex toy.

I chewed on this some more, and there's one other thing to note:

When we (I) say the canopy and pilot chute move with, or through, the air mass the same way, we must admit that they don't do so with the same efficiency. Two simple example cases can be considered:
1. If we say the canopy and PC have zero airspeed, we are basically saying the canopy and PC are simply moving with the air mass (thinking laterally here, as the canopy must continue descending). But the air mass won't move both of these things with 100% efficiency. Energy is lost to friction, heat, sound, and the evaporation of our fear-sweat.
2. If we say the canopy and pilot chute are both moving through the air mass, we know they enjoy different ratios of surface area to mass, and therefore move through the air with different efficiencies.

The canopy's behavior is quite largely dictated by the suspended mass, and therefore as a system, it has a MUCH lower ratio of surface area to mass than does the PC. Therefore, the canopy will move through the air mass more efficiently, and move with the air mass less efficiently than the PC.

Understanding this, we can see how the air could have a marginally different effect on the PC than it does the canopy. This difference is proportional to the difference in ratio of surface area to mass. This wouldn't result in the air tugging on the PC while simultaneously leaving the canopy unaffected, but it may be enough to see some visible offset of the PC.

So in the photo you attached, we can not conclude that the wind is affecting only the PC but not the canopy. We can conclude that the wind is affecting the PC slightly more than the canopy, which means the canopy has movement relative to the airmass from right to left. This results in the PC trailing dutifully behind the canopy to its right.

But I'd still venture to say the pilot, trying to compensate for a left-to-right drift, is giving the canopy some correction to the left.

Conclusion: as you scale up the size of the PC, we know it affects the performance of the canopy. But the difference in performance affects the canopy regardless of how it is flying through the prevailing winds. The effect will change slightly as the canopy faces this way or that way, but the delta in effect is small in comparison to the overall performance change. We're getting into some heavy ratios here.

I have to pee really badly, so I'm going to go do that. Then I'll come back and think through these fractions some more...

(Bonus question...if a BASE canopy leaves St. Louis heading west at 11mph and a speedwing leaves Toronto at the same time heading north at 18mph.....?)

that is more of what i'm getting at... they will undoubtedly suffer differing effects and you cannot assume that there is any constant involving towing a PC...

also, what started this whole silly debate... my main point is that a pilot who is comfortable with their gear, knows how to achieve the proper approach and landing with it.

very similar to deciding between landing an airplane with full flaps, or no flaps.

anyway... off to adventure!

'Zactly


Yup!

In a similar manner, familiarity with our own gear allows us to filter the advice we receive.

Blitzkrieg and I would like you to take the following away from this diatribe, and if I'm putting words in his mouth, he can punch me in it. (Careful with that last pronoun.)

***Just because your buddy jumps a 48" PC off the 300' freestander doesn't mean you should.***

***Just because your buddy jumps a 48" PC off
the 300' freestander doesn't mean you should.***

I agree!!

And for what little it is worth, I have jumped
from 300 feet many times with the following:
-vented 42
-non-vented 42
-vented 48
-non-vented 48
-PCA
-TARD
-Static Line

As the "Articles" say it is better to have a pinch
more PC than you need than the other way around
but as you get more experience each jumper should
find the right PC for the height, delay, their weight,
the size of their wing, and any trees that may need
to be cleared to reach the desired landing area....

Agree with everything but their weight. Don't think it should matter unless you are saying that in reference to drag and wingloading.

All a PC does is create drag to pull out the container. As long as you weigh more then the pressure it takes to pop your pins the jumper weight is of no concern to PC size.

Correct me if I'm wrong and I'll quit jumping. ;)

but the more you weight the bigger canopy you have and you would want bigger pilot chute to pull you to linestretch after the pins pop depending on speed

Like I said in my post, drag and wingloading. As in drag it out of the container and wingloading because if you weigh more you jump bigger canopies to stay within a desired wingloading. I'll just pretend my first post was more detailed and that you were just active listening.

I usually never read and never remember more than one post

Kill cone on the bridle?

It could give you uneven flight just as it "kills" the PC and potentially snag on the pins resulting in that it does not kill the PC.

Maybe this is "fixing the engine" when it's the landinggear that is the problem?

(Sorry about the off-topic post)


I completely disagree but am open to discussion. When you flare a canopy you translate airspeed into lift. I believe that is true of any airfoil. My experience with the Lightning tells me it applies to that airfoil for sure.


At least we agree that they are great CRW canopies but I have no clue where you are coming from when you imply that when brakes are applied on the Lightning the only response is the slowing of forward speed. Rate of descent slows also, which tells me that more lift is generated.

I get great landings on my Lightnings and recently my landings are getting even better because I am using a different technique than before. That's probably a topic for a different thread or maybe just PMs, though.

Sorry--back to our regular discussioin.

My first BASE jumps were on a PD190 9-cell loaded at about 1.1 and using a 52 in. F-111 monster of a PC. It slowed the canopy's forward speed for sure but I still had plenty of flare left for landings. Not recommending this configuration--just citing it as an example that the effects of a PC on canopy performance can vary greatly from one canopy to the next.

Qualitatively speaking, if a canopy has massive flare power with a small PC, I would expect it to have a solid flare even with a very large PC. If a canopy has marginal flare with a small PC, I would expect the flare with a very large PC to be less than marginal.

Someone mentioned a 52 in. ZP PC earlier. I made a ZP PC that is (as I recall) somewhere around 52-54 in. I ran across it recently and got quite a laugh. It looks ridiculously huge. I cannot imagine being willing to make any jump that would require a PC like that.

There was some mention of kill cones also. Kill cones have proven to be a nice thing for CRW and I have them on all my CRW canopies but I would be hesitant to put one on a BASE canopy because I think there is great value in keeping things simple in critical gear applications.

Walt

PM sent

52 inch PC's? OMG that's almost as big as my TV! I wanna cliffjump it as a main into water! Can we bring it on a skyjump and measure the resulting terminal velocity? :D

I need to dig that thing out one of these days and take a pic. LOL

Walt

While dragging a big PC in full flight... I wouldn't think canopy size would matter THAT much More so, a jumper's weight. -And yes, it would be important to understand the difference.

I've never heard the argument before but I've always thought that a massive PC would mess up the flair. That's why I sold my 48 and kept my 46 (might not be that much of a difference but it helped my peace of mind)

Yeah I'd never heard the argument before either. And I've already traded out my 48. I'll stick to my 42 and if it's too low I'll take a pca. Or just sit one out.

As for all of the info on this thread, every bit of it is greatly appreciated.. thanks.

Mark Hewitt, BASE 46, the inventor of most of the gear that made BASE jumping possible, was really the first to take note of canopy distortion from very large pilot chutes on smaller canopies. This was back in the mid-1980s and the idea was proliferated in some of the BASE magazines, particularly by Gerry Harendza's BASE newsletter. However, it was only really noticeable when the pilot chute was very big, like the 52 inch Para-innovator and when the canopy was a smaller skydiving type canopy. Those canopies were not BASE specific and were strange things like Pegasus canopies, Units, Nimbus, StratoCloud, Fury, and even something more acceptable like the Raven, etc. The effect was particularly noticeable on the PD reserves. The Raven actually did pretty well compared to a lot of the other canopies. I have never seen a modern start-of-the-art BASE canopy suffer from distortion and the resulting unusual stall point from a large pilot chute. A 48 is large, but it's not that large. I think it was canopy inexperience in an unforgiving environment coupled with jumping from too low an altitude for an inexperienced jumper.

At that time with the BASE Newsletter.
Trying to educate the importance of the " Line Mod "

Curly wwarped willl remove this post soon.

Wow
Time's are changing !

First, let's hope that curly wwarped is doing good since your wing's got clipped. You'll survive, just be a nice BASE Jumper ?

Second,
Back untill I get banned again...

The "Line Mod" is a tool.

Don't know how there getting away with it, Tandem BASE....
Eventually a line over will happen.

On a softer side, 110' water.
MillCreekpUSSIe.com

YouTube

Do you know Gerald?


Why all this concern for wwarped? Aren't you two in a spat?