JVX VELO size comparison

[marks 0]

I own a JVX 84 and a Velocity 84. I decided to lay the canopies on top of each other to prove or disprove the idea that they were different sizes. see the pics added and check for yourself.

you can see the JVX is on the bottom and the Velo is layed on top. it is clear the JVX is larger in size. the right wingtip and the right front of the nose were lined up together. you can see 9 inches extra on the JVX on the left wingtip, at the same time you can see 4 inches extra in the tail... do the math, but I will guess it is about 4-6 square feet different.

I assume that this WILL NOT scale in sizes, so your difference may be greater in larger size and smaller in smaller sizes, but this is just a guess..

these pics were taken with my cell phone so they are not so great.

I suck at web pages, so forgive the mess when you get there...

Pictures

[SkymonkeyONE 3]

Mark, you are at least the third person, including myself, who has done the "lay on top" drill. JVX's are definitely placarded MUCH smaller than PD's (and everything else measured like PD's). Again, a Velo 79 is exactly the same size as a JVX 70 by our comparison here at Z-hills.

Chuck

[Canuck 0]

If Jim was allowed on this site, he would pipe up that it's not a fair comparison because of blah blah blah. But I've seen several people buy a JVX, put a handful of jumps on it, and sell it to get one 10 sq. ft. smaller. Anybody compared a VX and JVX? You've got one of those too, right?

Canuck

[airborne82nd 0]

the velocity is a 7 cell and the jvx a 9

what is the aspect ratio of both.????

so the velocity uses a different way to measure? then icarus??

would the velocity have a faster turn rate then the jvx???

very interesting on the comparison

[freeflyn 0]

My JVX 77 fits perfectly on with my Velocity 84.

[NewClearSports 0]

In Jims defence he is the only one that has the balls to say "you can go a size down". & optimum WL is ...., and it actually is!
Everyone else says "refer to the charts" which is a bunch of bs. I bought my 1st X-braced (A velo) buy the chart under "Expert" and it was WAY too big. I could do chin up on the front risers. Sold it after 100 jumps for a much smaller Xaos and loved it.
I finally got to jump my JVX 84 hybrid this weekend and it is Awsome!! If I was to buy a Velo 90 would be my optimum size, but when ordering my JVX i knew to order an 84 buy what I read on jim's site and our E-mails. My JVX is perfect, can't wait to jump it again ... and again, and again...

Anyway, Velocity's are like belly buttons and A-holes, Everybody's got one, even your grandma. JVX's are Sweet.

[RMURRAY 1]

if it were me, I would not build in any real meaning into the number (ie JVX 84). Do the research, make lots of phone calls, demo (if possible) then buy. The first people getting jvx's were at a disadvantage - that is not an issue now....

rm

[breadhead 0]

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decided to lay the canopies on top of each other

For what it's worth: I did exactly the same with a JVX 90 and a Velocity 90, and came to the same conclusions.

[NewClearSports 0]

Hey Rob,

I see you can't sleep either since I know your in the same time zone as me. For me it's partly because I'm still pumped from jumping my JVX this weekend. Boy is that lit'l puppy groud hungry, my 1st jump I was open at 6k and the other group opened at 3k, we all landed about the same time.
Sometime this summer I would like to check out your RDS system. Do you think it would fit my 84? Do you have an attachment point on your JVX?

Blue skies

Mike

[rhys 0]

Congrats on your JVX84 hybrid,

I have that same, I would have purchase a larger size if i was getting something else but I did the research.

I too have only jumped mine a couple of times, I just attached a para concepts RDS but haven't jumped it yet with that on.

The para concepts RDS is the nicest I have seen but I can't comment on how it performs. i did question Lord Slaton on the issue and he said that the para concepts system was the most suitable for a JVX.

It sure is weird packing with no stabalisers.

"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

[RMURRAY 1]

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Hey Rob,

I see you can't sleep either since I know your in the same time zone as me. For me it's partly because I'm still pumped from jumping my JVX this weekend. Boy is that lit'l puppy groud hungry, my 1st jump I was open at 6k and the other group opened at 3k, we all landed about the same time.
Sometime this summer I would like to check out your RDS system. Do you think it would fit my 84? Do you have an attachment point on your JVX?

Blue skies

Mike

you should confirm but my rds (paraconcepts) should work with your canopy because they only make 2 sizes of sliders for the jvx - "small" for 96 and smaller, big for larger. sure, give it a try but you can save time by just getting one - you will not regret. yes, I have an attachment point - I'm not that hardcore!

rm

[SkymonkeyONE 3]

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In Jims defence he is the only one that has the balls to say "you can go a size down". & optimum WL is ...., and it actually is!
Everyone else says "refer to the charts" which is a bunch of bs.

Possibly the dumbest reason I ever read for buying a canopy. The JVX is a wonderful canopy. There are a few of them here at Z-hills and guys are ripping it up under them. In my opinion, though, there is simply no excuse for what I consider to be "manipulation of numbers" in order to quantify a "smaller" canopy and a trend towards "higher wingloading." Listen, you are not loading that "smaller" JVX higher than the guy under the larger velo. That inaccuracy would actually fuck you if you jumped at some dropzones with wingload restrictions. Ultimately, I definitely don't think it makes anyone cooler just because they run around spouting stuff like "I jump my JVX at 3.0 wingload." Personally, I don't care what your or anyone else's wingload is; I just wish all canopies were measured the same.


Someone also mentioned aspect ratio. I will repeat myself by telling you that a JVX 70 has the exact same dimensions as a Velocity 79. That's total size, both span and chord.

Chuck

[polarbear 1]

I've also observed the measurement difference, first comparing a JVX 87 to Velo 90 and then a JVX 83 to a Velo 90. The JVX 83 seems to be just about the same size as the Velo 90.

I don't think that entirely explains the super-high wingloading preference of the JVX, though...I wear more lead with the JVX 83 than I did with the Velo 90 and it just keeps going. I've worn as much as 35 lbs with both canopies, which puts me at 2.6 on the Velo and 2.85 on the JVX. The Velo flew well but it felt 'overloaded'...the touchdown was hard and it didn't seem to actually be performing any better than at 2.4-2.5.

The JVX at 2.85 I could still run out on my feet no problem and it actually seemes to prefer that heavy of a wingloading.

"Holy s*** that was f***in' cold!"

[rhys 0]

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Someone also mentioned aspect ratio. I will repeat myself by telling you that a JVX 70 has the exact same dimensions as a Velocity 79. That's total size, both span and chord.

That is while deflated and lying on the ground though isn't it?

The proflile of a JVX is much thinner than a velocity so when inlflated those sizes will not be the same anymore.also by that example a JVX 70 will have a higher aspect ratio than a velocity 70 but with more surface area?

per PD's website the aspect ratio of the Velo 103, 96 and 90 are all 2.69:1. 120s and 111s are 2.71:1 and 84s and 79s are 2.68:1. blah blah blah...

Why get your tits in a tangle over figures now, NZAerosports canopies have had a different sizing method from the start have they not? Considering Jyro developed his own computer cutting technique especialy for but not exclusivly for x braced parachutes I think they know what they are talking about. who says the PD method of measuring is the correct one.

And to say it is a tactic to make people look cooler by having a seemingly higher wingloading is a load of crap!

Just jump what you like. it is your choice. they(velocity,xaos,fx,vx, jvx)are all good canopies and have different charachteristics.

I love choice, don't you?



blue skies,

rhys

"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix

[polarbear 1]

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Someone also mentioned aspect ratio. I will repeat myself by telling you that a JVX 70 has the exact same dimensions as a Velocity 79. That's total size, both span and chord.

From my observations, the canopies have roughly the same dimensions. They have pretty different planform shapes which probably means they have different aspect ratios.

Having said that, I doubt the aspect ratios are that different - certainly not as much as you find comparing a conventional 9-cell to a conventional 7-cell.

"Holy s*** that was f***in' cold!"

[Spizzzarko 0]

"I suck at web pages, so forgive the mess when you get there"

Yea you do! Just kidding. I have never done a web page before I but I have looked at a lot of them. hahahahahaha

I did the same test with a 89 JVX and a 90 Velocity. There was quite a difference in sizes. I then laid out my 96 velo on my 89 jvx. They were very similar in sizes.

It seems as if the two are measuring approx 7 sq ft or so differently. I do agree with Mark that the sizes probably do not scale evenly between the two canopies.

Lord Slaton has always said that comparring the JVX to the Velo is like camparring apples to oranges. I am beginning to believe this. Nothing against the JVX it is a killer canopy and I will buy another one as soon as one of you guys out there buy my 89. It is for sale BTW so go and check the classifieds. I am just looking for a little more of a wing loading this season as I have lost a little weight. Don't worry there is still plenty of me to love (where it counts) but just a hair less in the fat area. hhahahaaaa

I do kind of agree with Chuck when he says 7sq ft is to much of a measuring fudge factor but canopy measuring has always bee a fairly nebulous process. It seems as is no two manufacturers measure the same.

Conversely, if you are going to bash the jvx for sizing irregularities then you really need to bash PD for being cryptic about the pack volume of their new reserves. They are saying that you should be able to get one size down packed up into your container. Most of the people I have talked to and with my limited experience with the canopy you should be able to get two sizes.

I am not sure if the manufacturers are measuring just bottom skin length x width and subtracting the area for ellipticallity of the canopy, or if they are factoring in other variables. Lord Slaton did tell me that the JVX and VX measure exactly the same. In the past I have talked to Sandy Reid of RI and he told me that there is a PIA method for measuring canopies but it is a very convoluted process with lot's of ins and outs and that is kind of why most manufacturers have done their own thing. I tend to believe him as he kind of knows what he is talking about.

So this canopy measuring issue is just not confined to one manufacturer, but more of a systemic issue industry wide. I will call PD and ask them how they measure their canopies. Then if the process is not to freaky deaky then I will try and measure my JVX accordingly.

I know this is not solving the problem but since most people are jumping the velos I will compare the jvx against that. I do not want to start a brand war here because in that issue no one wins. I think both canopies are great. I still own my 96 velo and have no plans on selling it.

[Spizzzarko 0]

OK I have just gotten off the phone with PD. I actually learned a lot about canopy measuring among other things. Those are some pretty informative folks that really care about customer service. If you have a question just send em an e-mail or call them up.

CANOPY SIZING:
It was explained to me that in the early days of canopy measurement many manufactures made up their own methods of sizing. Eventually PIA came up with a standard but few manufacturers used it because they had their own system and didn't want to change.

Again as I said in my earlier post canopy sizing is a little more than just measuing span x chord and subtracting the missing area due to the ellipticallity of the canopy. That is one way to do it, but we have to take into account that would give us some relatively skewed numbers because a canopy is not all nice a flat when it is inflated and hurtling you towards the earth. If we had a 1 cell canopy it would cease to be rectangular when inflated and become fairly tubular (Totally Tubular Dudes!). Well we do not have 1 cell canopies we have 7, 9, 21, and 27cell canopies. Now when each of these cells inflate they want to go tubular, but there is the next cell there to keep it square. The only places it can expand is on the top skin and on the bottom skin. This is what happens when you kite a canopy or if you were to inflate it over a table and try to measure it. Remember we are not dealing with a solid object. Take a look at canopies when they are landing in turbulance. They breath and expand and contract. Even your tiny little fast canopies do too! This inflated expansion actuall shrinks the spanwise measurement of a canopy 10%-20%. Think about it. If we were to measure the top skin (most manufactures use the top skin) with span x chord and subtracting the missing area for the elipticallity when the canopy was laid out on a table we would get one number. Now if we inflated that canopy just above that table with a fan that measurement would shrink because the top skin between the ribs would be bulging out. This causes the span wise distortion in the measurement between inflated and not inflated. The chord measurement shrinks far less because the canopy does not distort in that direction as much.

Now if we were to measure the thickness of the same uninflated canopy from top skin to bottom skin we would get one number. If that canopy were inflated on top of our table again with a fan then we would notice a 10%-20% increase in that measurement because of the canopy expanding and trying to become totally tubular. Now if we were able to take this measurement if actual flight the number would again be different. This time the airflow over the bottom skin would be pushing the bottom skin back into a flat or concave surface. The top skin on the other hand continues to bulge out because of the internal presure of the canopy and the low pressure on top of the wing because of lift.

Another reason that the flying wing is smaller than the canopy laid out is because of the anhedrial. We know that canopies are not completely flat in the air and that they are curved down towards the wing tips compared to the center cells. Skydiving canopies are not as bad as paragliders but if we took a paraglider for example and measured it's span on a table not inflated and then measured the span in the air our numbers would be vastly different. Remember that the part of the wing producing a horizontal component of lift does you no good when you are measuring the amount of lift pulling you up vertically. This is why Cross Bracing is so effective as it keeps the top skin from distorting as much.

Another interesting fact that I gleamed from my conversation with the PD engineer was that canopy flight and opening characterists do not necessarily scale up and down as size does. This is why you don't see 190 velocities or even 135 jvx's. If you had a 100 sq ft (10' x 10' for ease of math) canopy and you wanted to double it by doubling the line length and making it a 20' x 20' canopy you now have a 400 sq ft canopy. Do you see what I mean by scaling?

In conclusion there are as many different measuring techniques as there are manufacturers, and there are even variations within the same technique of measuring. Therefore canopy size is not a very good indication of flying characteristics from one canopy to another and even the same canopy of a different size. It is easy for us to assume that an 89 JVX should measure out to be very similar to a 90 velocity. That just is not true, and now with the growing popularity of different cross braced canopies we really need to find a better comparrison tool than just size, because using just size to compare the two is comparing apples to oranges. I hope this helps out some. Now that I have learned all of this I feel that just laying canopies out and comparring their sizes is useless. I think the best way to compare the two would be to fly each canopy and compare them that way. In the end that is why we should be choosing one wing over another, because of it's characteristics not because of how it is measured. Ihope this helps out some. If you have questions please let me know.

Grant

[superstu 0]

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...we really need to find a better comparrison tool than just size...

how bout fast, really fast, really really fast, and nuclear?

Slip Stream Air Sports
Do not go softly, do not go quietly, never back down

[Spizzzarko 0]

I was thinking that we should just all whip it out and compare sizes. Who ever has the biggest would win and what ever canopy that dude owned everyone should buy it. Of course that would suck if some John Holmes dude was flying a lightning 218 or something like that, but your idea has merrit too.

[ianmdrennan 2]

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I was thinking that we should just all whip it out and compare sizes.

Grant, nothing on your body is long enough to 'whip'. It'd be the same as trying to 'whip' a toothpick through the air. I don't even think you'd hear the air displace....

Performance Designs Factory Team

[Spizzzarko 0]

I never said I would win...

Are you doing ok?

[diablopilot 2]

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Why get your tits in a tangle over figures now, NZAerosports canopies have had a different sizing method from the start have they not?

I believe that NZ Aerosports and subsequently the orginal incarnation of Icarus Canopies used the PIA established measuring method (circa 1999, 2000) like everyone else in the industry EXCEPT PD. This measuring method was created by the canopy manufacturing members of the PIA.

Circa 2001 or so, Simon Mundell authorized a change in the measuring of Icarus Canopies measuring to parallel that of PD. His decision was in conflict with the previous manufacturing methods used by Icarus and NZ Aerosports. It was a major disservice to the company.

----------------------------------------------
You're not as good as you think you are. Seriously.

[NewClearSports 0]

***sure, give it a try but you can save time by just getting one - you will not regret. yes, I have an attachment point

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Well I won't be getting one untill later this summer. I already went over budget with the JVX, the second "Pond Rig" (The 1st one was too small), and a new set of 24" risers. If I now told my wife I want to order a $330 US - RDS she would freak.

I just thought if you were down at Burnaby during the nationals or something, I would love to give it a try, but I know it's a bit of work to switch. I asked about the attachment point because I thought you could use my slider.

I'd be happy to just have a closer look at it! I know I can take your word on how it performs.

Hope to see you this season.

Mike

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[polarbear 1]

One thing I thought I'd add. While my JVX 83 seems to be about the same square footage as the Velo 90, it is a much thinner airfoil. The Velo is about an inch thicker at the thickest point of the airfoil. That in and of itself doesn't mean anything, but thinner airfoils usually are most efficient at higher speeds, which in the case of canopies means more wingloading.

"Holy s*** that was f***in' cold!"

[rhys 0]

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If I now told my wife I want to order a $330 US - RDS she would freak.

why not mod your stock slider with a couple of loops of tape and get some spectra from somwhere so you can still remove your pilot chute and D bag and stow your slider as normal? that would only cost a couple of $.

"When the power of love overcomes the love of power, then the world will see peace." - 'Jimi' Hendrix