PDR vs PDO performance

[SkydiverNigel 1]

Hoping someone here can definitively close out this post from another forum. In an apples to apples comparison, I find it hard to believe Optimums (TSO-23d) take longer or more height to open than PDRs (TSO version unspecified). Anyone here know the answer?


Re: [masterrigger1] Fatality, Russia, 05AUG16, video (ends just before impact) [In reply to] Edit | Delete | Quote | Reply
masterrigger1 wrote:

Optimum reserves take longer to open than regular PDRs? What is the source or evidence for this statement?

Yep. It was part of PD's advertising when they first came out.I am sure someone has access the earlier ads.

MEL

PDRs meet TSOs (Canopy characteristics doc on PD website is non-specific as to which revision).
Optimums meet TSO-23d

Either canopy should open in 250-300 ft max. The openings on PDOs may feel softer than on PDRs, but I can't see anything that says PDOs take more time or altitude to open....

Maybe someone from PD or an experienced rigger can chime in here?

Nigel

[pchapman 261]

SkydiverNigel

Either canopy should open in 250-300 ft max.

Nope.
Not unless you are bailing out of an aircraft moving horizontally, which is how the tests are done.

Unfortunately it is a big myth in skydiving, thinking the 300 ft thing is vertical, something that many people were taught at some point -- me too.

The vertical distance is needed doesn't have to be a lot more than 300 ft necessarily -- as long as there's no pilot chute hesitation -- but there's no requirement for it to be under 300 ft in a vertical drop.

In any case, the Optimum will meet the regs.

Some PDR's are of course C23d, while the older ones are C23c. (Some C23d ones are allowed slightly over 3s to open, as there is an allowance for higher gross weights, but its only a trivial amount except for the PD281.)

For both TSO's, most of the opening time tests are only done with a 170 lb person or dummy, and only up to 110 kts. It is only the strength tests that are done at max certified speed time 1.2 test factor -- and there are only 3 of them. The opening time rules apply there as well. Or for C23d, opening altitude can be measured instead, 300 ft max (again with slight additions for high gross weight canopies).

From what I've heard over the years, the suggestion is that companies have a tough time getting canopies to open fast enough at the slow speed tests, without opening too hard and fast in the high speed tests.

I suppose the place where differences can occur between the two models is if the Optimum has a short snivel (acknowledged in the Optimum flight characteristics document by PD), while the regular old reserve probably has no real snivel, like many typical old school F-111 canopies. Both might be open within the required 3 sec or so from pack opening, but with a snivel there might be more altitude loss and less shock on the jumper when it fully opens.

... But what this all means in terms of actual vertical opening distance, for the two canopies, I don't know.






[For those getting picky and into the details: In AS8015B, which gives the C23d specs, section 4.3.6 is about opening time or alternately distance. There's nothing about having the test dummy travelling vertically during tests. I believe the part about optionally measuring distance instead of time, where one is 'measuring along a vertical trajectory' is still about the measurement direction, not the actual direction of launch. OK?]

[masterrigger1 2]

Quote

In any case, the Optimum will meet the regs.

They probably meet the TSO-23d standards.They do not meet the TSO-23b or TSO-23c standards.

Also, if you are using a H/C that is TSO-23b or 23c rated, then the equipment that you install into should also meet those standards to be legal.
And yes, I am stating that an OPT that is certified as TSO-23d should not be installed into a TSO-23b or TSO-23c container because the standards are different and not compatible.

MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[riggerrob 558]

............ is if the Optimum has a short snivel (acknowledged in the Optimum flight characteristics document by PD), while the regular old reserve probably has no real snivel, like many typical old school F-111 canopies. Both might be open within the required 3 sec or so from pack opening ............
...................................................................

Pchapman,

John LeBlanc agrees with you on this point. As John explained to me: "Optimum starts to inflate earlier (than PD reserves series) but takes longer to inflate. Inflation takes the same amount of time (from showing a pilot-chute to slider down), but the user feels gentler opening shock."

OTOH We disagree on most other points. Most of my drop-testing experience was gained during the Aviator PEP certification process. We started with high-speed structural tests, dropping 254 pound dummies from a WW2- surplus B-25 Mitchel bomber. That week's worth of tests were done from 300 feet at 205 knots. The poor, old Mitchel bomber could only fly 205 knots with its bomb-bay doors open.
Once we completed the first round of tests, we strapped on more and more lead ingots, until we ran out of daylight Friday afternoon.
All the drops were from 300 feet AGL and all the canopies were fully-inflated (within 3 seconds) and descending slowly before they landed.

Velocity VECTORS can modify how much altitude is required for inflation. Since the first round of Aviator tests were dropped from 300 feet AGL, all canopies easily inflated before landing.
OTOH if you are in a jet fighter diving faster than the speed of sound, 10,000 feet might be too late for ejection.





[For those getting picky and into the details: In AS8015B, which gives the C23d specs, section 4.3.6 is about opening time or alternately distance. There's nothing about having the test dummy travelling vertically during tests. I believe the part about optionally measuring distance instead of time, where one is 'measuring along a vertical trajectory' is still about the measurement direction, not the actual direction of launch. OK?]

[JerryBaumchen 1,046]

Hi Peter,

Quote

a big myth in skydiving

The myth is that it is a req'd test; it is an alternative test, not a req'd test.

IMO anyone arguing about the 300 ft req'ment is wasting their time.

Jerry Baumchen

[JerryBaumchen 1,046]

Hi Mark,

Quote

the equipment that you install into should also meet those standards to be legal.

While I agree somewhat on a philosophical level, I have not yet seen anything from the FAA supporting your position.

Jerry Baumchen

[masterrigger1 2]

Quote

While I agree somewhat on a philosophical level, I have not yet seen anything from the FAA supporting your position.

Look at the old AC-105-2C regarding compatibilty. It is still a reference even though outdated.
I also have been advised that the standard of certification is the standard and it is to be maintained no matter what.

MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[Hooknswoop 19]

I originally brought this issue up in 2005:

AC-105-2C, 11e states:

“The strength of the harness must always be equal to or greater than the maximum force generated by the canopy during certification tests.

(1) In a case where the harness is certificated under TSO-C23b and the canopy under TSO C23c, the maximum generated force of the harness and container; i.e, Low-Speed Category (3,000 lbs.) and Standard Category (5,000 lbs.). In this instance, no additional marking on the container is necessary.

(2) In the case where the canopy is certificated under the TSO-C23b and the harness under TSO-C23c, the strength of the harness must be equal to or greater than the certificated category force of the canopy”

A PD-113R label shows the average peak force of 3639 pounds.

The Mirage is TSO’d under TSO-C23b, Low-Speed Category (3,000lbs.).

The way I am reading this is according to AC-105-2C, a PD-113R cannot be put into a Mirage. That also means any reserve TSO'd under TSO-C23d with an average peak force over 3,000 pounds can't go into a Mirage.

Derek V

[masterrigger1 2]

Quote

I originally brought this issue up in 2005:

...and you are 100% correct.

MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[JerryBaumchen 1,046]

Hi Derek,

Quote

Low-Speed Category (3,000 lbs.) and Standard Category (5,000 lbs.).

And I agree with what you say on a philosphical level. Yet, few if any riggers limit the canopies for the Mirage when assembling or packing them.

IMO where the FAA fails in this is that they make the assumption that the charts in NAS 804 will generate those force numbers.

I no longer have it, but back in about 1980 I received a letter from Jim Rueter, V-P of Pioneer, and in it he stated ( in no uncertain terms ) that a C-9 canopy at the weights/speeds listed would not produce forces of 5,000 lbs. I had written to him after I had completed the Strength tests per NAS 804. As I watched how slow the canopy opened ( 400 lbs at 200 MPH ) I could simply not believe that it was generating a 5,000 lbs load.

Jerry Baumchen

[Hooknswoop 19]

Quote

And I agree with what you say on a philosphical level. Yet, few if any riggers limit the canopies for the Mirage when assembling or packing them.

I'm not following you when you say limit the canopy. You cannot just placard for a reduced weight or speed.

Under TSO 23D, the reserve is required to have on it's placard, the average peak force generated that was measured during drop tests. Not all TSO C23d reserves have this data on the placard.

This force that is generated by deployment must be lower than the force the harness was certified to. For example, if the canopy generates 3,500 pounds of force and the harness is only certified to 2,500, then the harness is not certified to handle the load that could be put on it during deployment.

Derek V

[JerryBaumchen 1,046]

Hi Derek,

Quote

I'm not following you when you say limit the canopy.

Like a lot of things, I might have worded it better.

I am agreeing with you. Most riggers IMO are not limiting the canopies going into Mirages to those that have a measured force load of 3,000 lbs or less.

Jerry Baumchen

[Hooknswoop 19]

I'm following now, thanks
I don't think very many riggers are aware of this issue. It hasn't become a major issue because the harnesses are able to handle the load, it is only a legal issue.

I did ask Mirage about this and they said they would get back to me. That was 11 years ago.

Derek V

[SkydiverNigel 1]

SkydiverNigel

Hoping someone here can definitively close out this post from another forum. In an apples to apples comparison, I find it hard to believe Optimums (TSO-23d) take longer or more height to open than PDRs (TSO version unspecified). Anyone here know the answer?


Re: [masterrigger1] Fatality, Russia, 05AUG16, video (ends just before impact) [In reply to] Edit | Delete | Quote | Reply
masterrigger1 wrote:

Optimum reserves take longer to open than regular PDRs? What is the source or evidence for this statement?

Yep. It was part of PD's advertising when they first came out.I am sure someone has access the earlier ads.

MEL

PDRs meet TSOs (Canopy characteristics doc on PD website is non-specific as to which revision).
Optimums meet TSO-23d

Either canopy should open in 250-300 ft max. The openings on PDOs may feel softer than on PDRs, but I can't see anything that says PDOs take more time or altitude to open....

Maybe someone from PD or an experienced rigger can chime in here?
gel

So I'm seeing some good debate on harness vs canopy opening forces strength, and potential to use an under-rated harness with some reserves.

But I'm not seeing any significant differences in opening times ( 3 secs or less) or altitude needed for full infation.

Have I got that right at least?

[riggerrob 558]

Hooknswoop

I'm following now, thanks
I don't think very many riggers are aware of this issue. It hasn't become a major issue because the harnesses are able to handle the load, it is only a legal issue.

I did ask Mirage about this and they said they would get back to me. That was 11 years ago.

Derek V

.........................................................................

If I hear the word "legal" one more time, I am going to vomit all over your shoes!
You guys are sounding like lawyers.
I fear lawyers because of the misery they have dragged me through over the past eight years ..... with no end in sight. GRRRRRR!!!!!

Lawyers argue subtle wordings while ignoring the bigger engineering issues. Yes, the harness must be stronger than the opening shock, so that it does not tear.
Since low-speed canopies and hard-opening canopies have disappearred from the skydiving scene, that side of the debate is irrelevant.

As for modern Mirage harnesses not being strong enough to meet TSO C23B standard category opening shock ... I say "poppy cocks!"
My 1985-vintage Mirage was as strong as a Vector or Racer harness .... similar materials, similar hardware, similar thread and similar stitch patterns.
Twenty years later, Mike Johnson (sp?) designer of the modern Mirage G3 and G4 harnesses showed me a stack of drop-test data. I vaguely remember him saying that the drops were done on PD's drop test tower. He concluded that modern Mirage harnesses (doubled Type 8 MLW) were
slightly stronger than older Mirage harnesses because Type 8 stretches slightly more than Type 7. That additional stretch allows webbing to absorb opening shock slower. The Mirage factory did not apply (to the FAA) to update their certification because repeating all the drop-tests to TSO C23D standard was cost-prohibitive.
The FAA has long allowed parachute factories to continue manufacturing "aircraft accessories) under older TSOs provided they keep the fatality rate low.

In the end, you guys sound like a mob of "barracks lawyers" when you argue over subtle differences in wording while ignoring engineering data.

[Hooknswoop 19]

Quote

In the end, you guys sound like a mob of "barracks lawyers" when you argue over subtle differences in wording while ignoring engineering data.

What engineering data?

AllI have as a rigger is that the Mirage is TSO'd in the low speed category and some PD's can produce more opening force than the harness is certified to. No "subtle wordings".

Derek V

[riggerrob 558]

Hooknswoop

***In the end, you guys sound like a mob of "barracks lawyers" when you argue over subtle differences in wording while ignoring engineering data.

What engineering data?

AllI have as a rigger is that the Mirage is TSO'd in the low speed category and some PD's can produce more opening force than the harness is certified to. No "subtle wordings".

.....................................................................................

And I just mentioned some drop-test results that prove that Mirage harnesses are plenty strong enough for TSO C23D.

[JerryBaumchen 1,046]

Hi Rob,

Quote

you guys sound like a mob of "barracks lawyers" when you argue over subtle differences in wording while ignoring engineering data.

I do believe that I understand your position on this issue. However, more than anyone else on here, you have posted, many times, things such as: 'And you will stand alone in court.'

Quote

I just mentioned some drop-test results that prove that Mirage harnesses are plenty strong enough for TSO C23D.

In the eyes of the FAA, it is still certificated under the Low Speed category. If one wants to protect their rigger's ticket, IMO they should do that which keeps them out of trouble with the FAA.

Just my $0.02 on this. And let me add, it is very easy for me to say this as I no longer pack reserves.

Jerry Baumchen

[SkydiverNigel 1]

riggerrob

***I'm following now, thanks
I don't think very many riggers are aware of this issue. It hasn't become a major issue because the harnesses are able to handle the load, it is only a legal issue.

I did ask Mirage about this and they said they would get back to me. That was 11 years ago.

Derek V

.........................................................................

If I hear the word "legal" one more time, I am going to vomit all over your shoes!
You guys are sounding like lawyers.
I fear lawyers because of the misery they have dragged me through over the past eight years ..... with no end in sight. GRRRRRR!!!!!

Lawyers argue subtle wordings while ignoring the bigger engineering issues. Yes, the harness must be stronger than the opening shock, so that it does not tear.
Since low-speed canopies and hard-opening canopies have disappearred from the skydiving scene, that side of the debate is irrelevant.

As for modern Mirage harnesses not being strong enough to meet TSO C23B standard category opening shock ... I say "poppy cocks!"
My 1985-vintage Mirage was as strong as a Vector or Racer harness .... similar materials, similar hardware, similar thread and similar stitch patterns.
Twenty years later, Mike Johnson (sp?) designer of the modern Mirage G3 and G4 harnesses showed me a stack of drop-test data. I vaguely remember him saying that the drops were done on PD's drop test tower. He concluded that modern Mirage harnesses (doubled Type 8 MLW) were
slightly stronger than older Mirage harnesses because Type 8 stretches slightly more than Type 7. That additional stretch allows webbing to absorb opening shock slower. The Mirage factory did not apply (to the FAA) to update their certification because repeating all the drop-tests to TSO C23D standard was cost-prohibitive.
The FAA has long allowed parachute factories to continue manufacturing "aircraft accessories) under older TSOs provided they keep the fatality rate low.

In the end, you guys sound like a mob of "barracks lawyers" when you argue over subtle differences in wording while ignoring engineering data.

Why so angry? Seriously, I was looking for an answer to what I thought was a reasonable and straightforward question...

[masterrigger1 2]

Quote

But I'm not seeing any significant differences in opening times ( 3 secs or less) or altitude needed for full infation.

Have I got that right at least?

No, sir you do not.

Here is a five minute query on YouTube that resulted in two somewhat similar types of malfunctions.The PDR one is spinning a little less, but the OPT is traveling at a higher speed also.

One is with a PDR without a Skyhook.

https://www.youtube.com/watch?v=T2ekBNYCk_s

The other is with a Skyhook and a OPT.

https://www.youtube.com/watch?v=ctim2aDfQJs

View them and let me know if they open at the same speed or not.

Better yet, get a stopwatch and some popcorn and watch a few videos.They are out there if you look for them.

MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[Hooknswoop 19]

Quote

In the end, you guys sound like a mob of "barracks lawyers" when you argue over subtle differences in wording while ignoring engineering data.

What engineering data?

AllI have as a rigger is that the Mirage is TSO'd in the low speed category and some PD's can produce more opening force than the harness is certified to. No "subtle wordings".

.....................................................................................

And I just mentioned some drop-test results that prove that Mirage harnesses are plenty strong enough for TSO C23D.

You "just mentioned" does not equal "engineering data". I still have not seen any engineering data and therefore it is impossible I am ignoring any engineering data.

As a rigger, what do I have to go by? Someone mentioning some drop test results they heard about? Nope. All I have is the FAR's. Mirage is certified in the low speed category and some PDR's exceed what the harness is certified to. Will it handle more? Sure. Doesn't matter.

I can't put 1.2x the max weight on the reserve data card that the reserve was certified to because I know it held together at that weight during tests. I have to put what the reserve is certified to.

Derek V

[SkydiverNigel 1]

masterrigger1

Quote

But I'm not seeing any significant differences in opening times ( 3 secs or less) or altitude needed for full infation.

Have I got that right at least?

No, sir you do not.

Here is a five minute query on YouTube that resulted in two somewhat similar types of malfunctions.The PDR one is spinning a little less, but the OPT is traveling at a higher speed also.

One is with a PDR without a Skyhook.

https://www.youtube.com/watch?v=T2ekBNYCk_s

The other is with a Skyhook and a OPT.

https://www.youtube.com/watch?v=ctim2aDfQJs

View them and let me know if they open at the same speed or not.

Better yet, get a stopwatch and some popcorn and watch a few videos.They are out there if you look for them.

MEL

PDR + Skyhook vs PDO - Skyhook is hardly an apples to apples comparison.

And Youtube videos are anecdotal; I prefer the controlled engineering test data collected for certification to some random dude's 'Shit there I was...' story.

Bottom line, I'm not seeing any credible evidence to show that PDOs are less safe than PDRs.

[masterrigger1 2]

Quote

PDR + Skyhook vs PDO - Skyhook is hardly an apples to apples comparison.

You would be right IF that were the case. The videos I posted was a PDR without a Skyhook and the second was a Skyhook and a OPT. So with that said, the OPT with the Skyhook should be faster; it is not!

Quote

And Youtube videos are anecdotal; I prefer the controlled engineering test data collected for certification to some random dude's 'Shit there I was...' story.

The YouTube videos are not anecdotal. The definition of anecdotal is basically a personal account of events without solid, verifiable facts.

Video is/can be a true factual account of events, so they are not the same.

Also let me be the first to tell you, video is the primary "Test Data" collected during test drops.

Quote

Bottom line, I'm not seeing any credible evidence to show that PDOs are less safe than PDRs.

I would have to say you are not looking!

Just ask someone with a data logger that had a reserve ride with a PDR to download the data and one with a OPT. Then compare the data.
It is that simple.

But then again, you are jumping a OPT...


MEL

Skyworks Parachute Service, LLC
www.Skyworksparachuteservice.com

[mxk 1]

SkydiverNigel

Bottom line, I'm not seeing any credible evidence to show that PDOs are less safe than PDRs.

Here's what Mark Procos from UPT had to say on the topic:

BPA Skydive the Expo 2015 - Equipment Compatibility with Mark Procos

Softer openings was one of the design goals for the OPT. That means covering longer distance, which may make it less safe than a PDR under specific circumstances (where many other variables and decisions come into play). On the other hand, it may be safer than a PDR at higher speeds or in situations where canopy size is a factor. I have not seen sufficient evidence to conclude that the OPT is inherently less safe than the PDR, but I do have my Vigil set to 1,250 ft to account for the longer snivel.

[gowlerk 1,901]

mxk

***Bottom line, I'm not seeing any credible evidence to show that PDOs are less safe than PDRs.

Here's what Mark Procos from UPT had to say on the topic:

BPA Skydive the Expo 2015 - Equipment Compatibility with Mark Procos

Softer openings was one of the design goals for the OPT. That means covering longer distance, which may make it less safe than a PDR under specific circumstances (where many other variables and decisions come into play). On the other hand, it may be safer than a PDR at higher speeds or in situations where canopy size is a factor. I have not seen sufficient evidence to conclude that the OPT is inherently less safe than the PDR, but I do have my Vigil set to 1,250 ft to account for the longer snivel.


Nice. That is by far the most realistic and sensible thing I've seen written about this subject. Design is compromise, and PD did not get something for nothing when they built in a short snivel.

Always remember the brave children who died defending your right to bear arms. Freedom is not free.