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hut4car

First main size, with prior canopy experience

Reasonable main size  

22 members have voted

  1. 1. What size main would be reasonable

    • 150
      7
    • 180
      9
    • 200+
      6


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Maybe beating a dead horse here, but this is what I'm looking at.

I have 2 static lines on a 220 and then 180 main, 10 min tunnel time, and have been speed flying for 8 years, current speed wing loading is about 2 on my 9m rapi-dos (95sqft) with a projected aspect ratio of 3.

I don't intend to be doing any swoops or notable low turns right off the bat, and I am generally reserved under canopy which will hopefully demonstrate diligence to my instructor. 

All this being said, if I am getting stable freefall and clean openings on whatever student rigs they put me on... wouldn't it seem completely reasonable for me to be eyeballing something like a 150 main as soon as I am ready to pick up a rig? 

Starting my A license course next week and plan to work with instructors so I don't have any issues with the DZ when I buy my first rig, but I want to pick something up early on.

 

48367841_10212103321011114_1154692693285142528_o.jpg

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Ok I'll bite, you do present an interesting case!  If the DZ has some good rental gear for downsizing, maybe you can at least convince them to allow a rapid downsizing. Back in the old days, early in the zero-p canopy era, if you were good you might do a couple jumps on a particular size canopy, then downsize a size, and repeat. If going to a sportier canopy, have a few jumps on a more docile canopy of the same size. Anyway, that was my experience in the early 1990s as someone who also thought they were a special case -- a pilot in my case.

Try to borrow rigs as well, if needed to help with the downsizing. At least then you might have an idea what works for you before you spend money on gear yourself.

If you're already on a 180 at 2 jumps that's just one 1 to 2 more downsizes to a 150 anyway.

I'm not a great source of advice as I don't speedfly (only paraglide). I'm not sure of the glide ratios current speedflying or riding canopies are built for, but I'd warn you to be careful of the more ground hungry skydiving canopies until you worked your way into them. At the same wing loading, there can be canopies of widely varying flight characteristics. I guess they aren't really common at say 150 size, but at 135 and under they start to be more common. They have a steep descent (say, glide ratio of under 2.5) and dive sharply in turns. So be careful of the model of canopy and not just size.

Whether you end up buying a 150 or whatever, it is just very difficult to know what to look for (in a rig, reserve, and main) when you've only barely started skydiving. You could probably fly and land smaller than a 150 easily enough, but you would also be learning to deal with packing, body position on opening, and dealing with other skydivers on opening and in the landing pattern. So who knows, maybe a 150 at 1.25 loading or thereabouts might be reasonable to stay at for a little while.  

 

 

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To add to what PC said, I will say you will need to learn to fly with canopy traffic also. This IMO is equally as important. If you are still a student, you probably don’t have to focus on this while landing yet which is a good thing as you need to focus on landing safely.

 

When you get licensed and jump with 20 plus canopies flying around trying to land in the same area, things change. Some folks are flying much faster and others much slower. Safely getting into the pattern is crucial to avoid a canopy collision or a low altitude mistake. Take this into consideration as you decide what is best for you and the others you will be flying with. Watching and talking to more experienced jumpers will be a great benefit.

 

BTW, what is your exit weight? That will help determine a safe canopy size.

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On ‎4‎/‎23‎/‎2019 at 8:59 AM, hut4car said:

All this being said, if I am getting stable freefall and clean openings on whatever student rigs they put me on... wouldn't it seem completely reasonable for me to be eyeballing something like a 150 main as soon as I am ready to pick up a rig? 

Stable freefall and clean openings have nothing to do with what canopy size is right for you. 

Based on your history, a 150 at 1.25 wingloading would probably be just fine as far as landings are concerned, depending on the type of main you are flying. 

As mentioned above the issue of traffic, especially in the pattern, is different than you are used to. Think about how will you react if someone is doing a downwind final at the same time you are on final into the wind or if the jumper in front of you is flying a larger slower canopy than you and you are overtaking them on your base leg or if someone cuts you off on final or if someone opens close to you and is flying right at you just as you are opening... There are many situations like these in which flying a larger slower canopy when you have little experience flying around other people is a good thing. Always consider worst case scenarios when deciding what wingloading is right for you.

Have you thought about your reserve size?  You are used to flying a nine cell at a higher wingloading, but have you ever jumped a 7 cell at a higher wingloading (or at all)?  Having never jumped one, would you like to land one at 1.25 into someone's backyard (or whatever area with lots of obstacles) at sunset because the spot sucked and you had a mal?  More square footage equals slower landing speeds equals a better chance of walking away from a worst case scenario. 

Regardless, make a point to take a canopy control course as soon as you can after you get off student status, preferably before you buy anything.  Probably seems silly considering your experience, but I can guarantee that you will learn something about how to safely fly in traffic and how to avoid canopy collisions (which kill skydivers way too often).

If your instructors feel that you aren't ready for a 150 yet, listen to them. They know more about skydiving than you do and they aren't trying to hold you back.  They only have the safety of you and everyone you will be jumping with in mind.   

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Maybe you should also consider that a smaller and especially more eliptical  canopy will  not open as reliable as your bigger more conservative canopyhavin. Most  of the time you will get away with having to go for the reserve but  there are things that can go wrong with emergeny procedurees aas well. This may apply to less experienced jumpers more than to routine jumpers. 

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I have 3 static line jumps, some tunnel time and fly canopies with totally different flight characteristics. I fly a 95’ canopy loaded at “about” 2/1. 

Why don’t you just say “I have mad skill”.

 

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On 5/6/2019 at 12:34 AM, ufk22 said:

I have 3 static line jumps, some tunnel time and fly canopies with totally different flight characteristics. I fly a 95’ canopy loaded at “about” 2/1. 

Why don’t you just say “I have mad skill”.

 

I skydive and speed-ride, the flight characteristics aren't all that different and I'd say a lot of the skills are transferable. As already mentioned traffic is a huge difference and if you're at a busy dropzone with a lot of canopies in the sky you don't really want to be going faster than a significant proportion of the load.

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(edited)

I also believe you can have a faster downsizing, but I wouldn't skip sizes. Even a simple malfunction on a smaller canopy can be much more intense than on a bigger size. The extra worry with the canopy may limit your progress in other areas of skydiving. There's just so much you can focus on each jump and variables like how many canopies are in the air, your opening altitude, decision altitude etc are all affected by your canopy choice. Where you jump, if you're willing to do more hop n pops etc... all have an impact on your decision. It's not just that you're capable to land the chute on ideal conditions.

Flying a rapido 9m safely is no joke, you probably have skills. I fly a 75sqft canopy myself, and have adventured myself speedflying. I flew a 13m spitfire, did about 50 flights and bought myself a mirage RS 11.5m. I got scared on a launch on my spitfire and never flew the mirage, decided to sell it until I have more experience. So, the crossover knowledge helped me but wasn't a complete replacement.

Edited by daffes

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Hey all just a quick update, the guy is a bit old school but seems to lend an ear to my thoughts. I have been progressively getting in jumps on a huge 280 student rig and simply demonstrating that I can come in and land like a normal person lol. It sounds like once I have a few more in things will be moving along about how I would find reasonable and I will be in the 150 sq range quickly which is worth while imo. Those student rigs dont teach me as much as I would like and shut down my chance to jump in some weather. I have been very aware throughout freefall, openings and altitude awareness thus far which were my main concerns.

Also, I have quite a bit of time dealing with air traffic from all the types of flying I have done... so that did go well but really was a great thing to make note of in consideration of my post.

Had a hoot with he guys on the DZ kiting the speedwing in between jumps btw, I love watching these sports mesh!

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9 hours ago, hut4car said:

Those student rigs dont teach me as much as I would like and shut down my chance to jump in some weather.

Not being able to jump in "some weather" is not a bad thing. I'm assuming that you mean higher winds. When the winds come up, the chances of shit happening go up too.  Forced to downwind it because of traffic, backing up on final, having to land out because the spot sucked... any one of those could end very badly and they can happen to anybody, regardless of their canopy experience or wingloading or type of canopy.  

Jumping when it's cloudy can lead to falling through them.  Falling through them can lead to really bad spots, or worse yet, collisions in freefall or under canopy. And if it is raining you are hitting the pointy end of the raindrops and that hurts! ;)

Like every other jumper out there, I have jumped in some pretty sketchy weather.  I don't do that anymore.  Skydiving is supposed to be fun; for me, jumping in sketchy weather is not fun.

The choice to jump in less than good conditions is often influenced by the sometimes overwhelming desire to go jump. There are numerous (read "far too many") examples of this being the first link in the chain of events that led to an incident.  

Just some more stuff to think about.  :)  

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at OP:

I figure you're just talking about being stopped from jumping in "some weather" due to winds. Not that you're hoping to jump through 10,000' of rain and cloud. (I personally think Skybitch's comments seem a bit harsh if they are a riposte to your comment, but are educational when talking about weather issues in general.)

Your being stopped from jumping in higher winds is probably more a function of what is allowed at your license level (assuming you are under USPA rules or similar), than the size of the canopy. One can fly big canopies in strong winds... it just gets a lot more challenging. I have jumped student size canopies where I've backed up right to touch down. Takes a little more planning and of course one can't do a regular pattern.

In some locations and cases, tons of wind will lead to tons of turbulence, in which case fewer and fewer jumpers, even experienced ones, will want to be in the air at all. In that case it isn't just about wind speed.

So yes you may feel more comfortable when maneuvering around with a smaller canopy when winds are higher, and may indeed be safer.  If an instructor grounds you due to winds though, it's likely because they are grounding all Students, and not just because you're on a 280. Still I hope you get to downsize a few sizes quickly from that level - especially when you've already flown smaller. (At a different DZ?)

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3 hours ago, pchapman said:

. (I personally think Skybitch's comments seem a bit harsh if they are a riposte to your comment, but are educational when talking about weather issues in general.) 

My intention was for my post to be educational. My apologies for it coming across as harsh. Was hoping to point out some things we can easily forget when we get antsy to jump.

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(edited)

Just something to consider:
The smaller the canopy, the smaller the margin for error.
The higher the WL, the smaller the margin for error.

Of zourse you chose a container suitable for that canopy and probably have an even smaller reserve, because that is what most jumpers have.

And now you're flying your reserve having to land off in high winds on a field surroudned by high trees and you are also wearing a few pounds of lead to keep up with your FS4 buddies.

Edited by Baksteen

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(edited)

Size doesn't matter so much as the wing loading.  The advice I was given by all of my instructors in student status was to remain at or below 1 lb/sq ft for the first hundred jumps AND can consistently stand up your landings in all wind conditions. 

I'm a big boy with an exit weight of 240 and so it took me some time to work down to the size I jump currently.

-JD-

Edited by skyfox2007

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12 hours ago, skyfox2007 said:

Size doesn't matter so much as the wing loading.  The advice I was given by all of my instructors in student status was to remain at or below 1 lb/sq ft for the first hundred jumps AND can consistently stand up your landings in all wind conditions. 

I'm a big boy with an exit weight of 240 and so it took me some time to work down to the size I jump currently.

-JD-

The wing loading doesn't work the same way for all people because a parachute is function of a cube and wingload is a function of a square. Volume vs plane. The wingloading is a starting point only not a hard reference.

Someone who weighs 110lbs exit weight would never be able to handle a 120 square foot parachute for the first main they get.

Check the notes in Brian Germain's downsizing chart for the non linear characteristics of parachute.

 

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5 hours ago, sundevil777 said:

I think you meant to write that the volume of a parachute is a cubic function, and that you meant to say volume vs area.  That is true, but not relevant.

True. Volume vs area (cube vs square) does not really apply to this.

But the idea that canopy size vs wingloading isn't linear is true. And that does apply to this.

A 'big boy' under a 200+ sq ft canopy at 1:1 is a very different situation from a 'little lady' under a 135 at 1:1.
Brian Germain generally considers anything 150 or below to be 'High Performance'. 

 

Also the fact that the OP has canopy piloting experience is a double edged sword. 

As a licensed fixed wing pilot, I had a fair amount of experience & understanding of landing patterns, how a wing landed, judging altitude, flaring, that sort of thing. I had less of a problem learning that stuff. However, there's a lot that didn't transfer and a lot that simply wasn't there. So 'knowing what I didn't know' (more accurately not knowing it) was an issue. Overconfidence was too. 
I'd suggest being cautious. Far, far easier to be 'slow and careful', even if it means sitting down some days. The potential consequences of going too fast are pretty serious.

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My goal wasn't to answer the original OP with my comment, only address Skyfox's comment for someone new reading this thread. I didn't see the "or below"  during my first read and I wanted to stop propagating the 1:1 hard rule that everyone blindly follow when buying their first canopy. 

On 8/5/2019 at 8:52 PM, skyfox2007 said:

Size doesn't matter so much as the wing loading.  The advice I was given by all of my instructors in student status was to remain at or below 1 lb/sq ft for the first hundred jumps

 

16 hours ago, wolfriverjoe said:

True. Volume vs area (cube vs square) does not really apply to this.

But the idea that canopy size vs wingloading isn't linear is true. And that does apply to this.

Could you enlightened me how the cube vs square does not apply to this?

I know that lines will be shorter on a smaller canopy than on a larger one. That alone contribute to the non linearity between the same family of canopies. Then the trim will also influence how the canopy dive and will also be different depending on the size.

My understanding is that the volume play a major role in the non linearity because the airfoil created is function of the volume inside. The image below is not perfect but it illustrate that when you play with the volume with slats (extenders in front of the wing) you change the volume of the airfoil therefore creating more lift. With canopy, we can only change the design to achieve the same effect. Having more lift (increasing size) is desirable for someone newer in the sport to prevent hard landings. 

Lift-Coefficient-Flaps.png.4882af6de278c1a0363135d8577dd2ed.png

17 hours ago, wolfriverjoe said:

A 'big boy' under a 200+ sq ft canopy at 1:1 is a very different situation from a 'little lady' under a 135 at 1:1.
Brian Germain generally considers anything 150 or below to be 'High Performance'. 

What I find inconsistent and unclear for a newer jumper is that we say things like 1:1 is different for X amount of weight vs Y amount but we can't really explain why to them because we need to explain the math behind. 

On the other hand, we say things like this that people take for hard rules
1-Stick to around 1:1 for your first canopy, no weight considered
2-You are under loading your canopy at .8, you should downsize

By using the volume, we would get a better general rule that could apply to all weight even though it would be less sexy to say stick to: .627 ft3
  

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" when you play with the volume with slats "

Sorry, that whole example with the diagram doesn't apply to this situation. A slat does a lot more for an airfoil than just extend the chord.

The lift coefficient won't change much with a change in an airfoil's size, within some reasonable range close to the original airfoil's size and speed used.  So just leave that diagram out of it. (Saying this as someone with an aeronautical engineering degree.)

 

I don't think canopy volume is the way to characterize how hard a canopy is to fly -- at least in comparison to wing loading modified (in a not precisely mathematical way) by size

Let's say you have a guy on a 200 canopy who weighs 200 lbs geared up. And a small girl on a 100 who weighs 100 lbs geared up. (Not trying to be realistic here, but to make the numbers easy.)  Wing loading is the same, 1.0. We already know that a tiny canopy will be a lot trickier to fly, even though the wing loading is the same. We know not to say, "They fly the same because the wing loading is the same."

But it is little use to talk about canopy volume instead. The canopy volume on the 100 would be about 35% of that of the 200 canopy. (Volume changes with the cube of the line length. Halve the canopy area, line length becomes 1/root(2) = .707.  Cube that =.353)

How does it help us to know the canopy volume is about a third of the original?  "Same wing loading" sure doesn't mean "just as easy to fly", but "about a third the canopy volume" doesn't mean three times harder to fly??

(Canopy volume on its own is a small factor, and isn't entirely irrelevant, as there is a mass of air in the canopy that has to be accelerated around when maneuvering. It can be some pounds of weight, with much less mass in a smaller canopy.  But I wouldn't make canopy volume the main focus.)

We know line length changes less fast than the area of the canopy changes. (eg, half canopy size = 71% of the original line length, or 29% less length) And that line length will affect dynamic canopy behaviour -- shorter pendulum swing will affect turning and stability, and a shorter control range to deflect the canopy trailing edge to the same degree. And the combination of those effects will be something else again.

So in this example we have all sorts of different size factors:

- wing load is the same, 100% of the original one could say

- line length is 71% of original (but maybe line length dynamic and control effects somehow multiply the difficulty for the jumper, creating a lower percent value)

- area is 50% of the original

- canopy volume is 35% of the original

None of these numbers alone seem to be "correct" in giving a guide to a jumper how much different a 100 lb jumper is on a 100 canopy, compared to a 200 lb jumper on a 200 jumper. I think it will be somewhere between that 100% the same and the 50% change of the area. The volume change (of about 35% of the original) is way too much to be useful for this.

In conclusion, while you might be concerned that "wing loading plus an adjustment for smaller canopies being trickier" is a vague way to give a guide to how a canopy will fly for a jumper, canopy volume isn't the way to go.

So things are pretty much as wolfriverjoe already stated.

 

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On 8/7/2019 at 11:29 AM, pchapman said:

but "about a third the canopy volume" doesn't mean three times harder to fly??

(Canopy volume on its own is a small factor, and isn't entirely irrelevant, as there is a mass of air in the canopy that has to be accelerated around when maneuvering. It can be some pounds of weight, with much less mass in a smaller canopy.  But I wouldn't make canopy volume the main focus.)

At some point, should the conversation include parasitic drag. 

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