PD Reserve versus PD Optimum Landing Kinetic Energy

[rjklein4470 23]

FYI, you can demo the reserves from PD. In the past I have always jumped my reserve as a demo. So if and when you have to goto your handles, that little voice in the back of your mind is gone.

Years ago I was flying a " Nova" this canopy will date me, lol. I had a small rip in one of my end cell's. About that time the NOVA was known to acting funny in turbulence low to the ground, collapsing. Even though MY NOVA with the rip was acting fine at altitude, flair was fine, turned fine, recovered fine, I still decided to chop it.

I had several jumps on my reserve as a demo, so in the end it was the right choice.

I sent my Nova back to Glide Path for the repairs, and they said that they would not repair it, but would replace the canopy or give me my money back. This is when the news of the canopy collapsing started to spread so I had them send me a check.

[shadeland 5]

rjklein4470

FYI, you can demo the reserves from PD. In the past I have always jumped my reserve as a demo. So if and when you have to goto your handles, that little voice in the back of your mind is gone.

Years ago I was flying a " Nova" this canopy will date me, lol. I had a small rip in one of my end cell's. About that time the NOVA was known to acting funny in turbulence low to the ground, collapsing. Even though MY NOVA with the rip was acting fine at altitude, flair was fine, turned fine, recovered fine, I still decided to chop it.

I had several jumps on my reserve as a demo, so in the end it was the right choice.

I sent my Nova back to Glide Path for the repairs, and they said that they would not repair it, but would replace the canopy or give me my money back. This is when the news of the canopy collapsing started to spread so I had them send me a check.

I may just do that later this year with a PDR 113 and Optimum 126 and take along a Flysight.

[shadeland 5]

JerryBaumchen

Hi Mark,

Quote

PD Optimums are certificated to the standards of TSO-C23d/AS 8015B.

I have posted about this before on this site.

At the 2005 Symposium, a friend and I were sitting in a restaurant with one of the 'major players' of PD. During the course of that discussion, he informed me that PD had gotten/obtained an exemption to the 'total velocity' req'ment of the TSO standard because their Optimum canopies exceeded the standard.

By how much, I have no idea.

I do not have anything in writing regarding this conversation. I was not told to keep this information to myself.

Jerry Baumchen

PS) I just did a quick review of all of the TSO standards & 'total velocity' first comes up in C23d, AS8015, Rev. B. It states ' . . . the total velocity shall not exceed 36 ft/s (11.0 m/s), in an unaltered post deployment configuration . . . ' Note that this is airspeed and not ground speed. If the dummy or you are going downwind, you will possibly be exceeding these limits.

I think there's an answer (or at least, an incomplete answer) to my original question: TL;DR Optimums would fly slower than their lower sized PDR counterpart. A PD Optimum 160 would (all things being equal) fly slower (total velocity, in both vertical and horizontal component) for a given wingloading than a PDR 143.

Jerry had learned at a symposium at the Optimums exceed the TSO standard for total velocity, and that may be the origin of the assumption (a reasonable one) that Optimums descend faster than non-Optimums (or other canopies).

I believe now that not the case. I think that both the Optimums and current PDRs also exceed the TSO standard for total velocity, as demonstrated by their maximum allowed weight. If you look at the Optimums and PDRs, they both allow WL around 2.0. I have to imagine that 36 ft/s (24 MPH) will be exceeded on almost any wing at 2.0.

The Aerodyne Smart reserves also allow maximum weights that put WL above 2.0.

Interestingly enough, the Icarus reserves and Icarus Nano reserves both have maximum wingloadings at 1.3ish. My guess is they didn't get a waiver for the total velocity.

I would speculate that the waiver was granted because typically the pilot of the wing can flare and place the total velocity well within standard. If no inputs are made though, the landing could of course be bad.

With that, my assumption now is that yes, an PD Optimum of a higher size will lower your descent speed compared to a smaller wing (PDR one size small). More data is needed however.

[pchapman 261]

Hang on, I always thought that the TSO requirements had to be met at the TSO weight, not at whatever the company "recommend".

Or is that incorrect?

So if a company says "don't jump this 120 at over 160 lbs", that's just a recommendation which may be conservative or not. What matters is that the canopy is for example certified to 254 lbs -- and that's where the velocity requirements apply.

PD is more liberal than some companies in what they 'recommend'. That's due to canopy design in some cases (eg comparing to an old school Raven), while in other cases it may be just less conservative. (eg modern, heavy duty reserves like the Nano or Speed, having low 'maximum' weights if I recall correctly -- sorry no time to check manuals right now).

Some may call that 160 lbs the maximum, or maximum suggested or maximum recommended, or some other term, where each company has its own wording.

But the TSO weight (eg 220, 254, or 300 lbs) is the one that is the real weight that matters to the FAA. Isn't it?

[shadeland 5]

pchapman

Hang on, I always thought that the TSO requirements had to be met at the TSO weight, not at whatever the company "recommend".

Or is that incorrect?

So if a company says "don't jump this 120 at over 160 lbs", that's just a recommendation which may be conservative or not. What matters is that the canopy is for example certified to 254 lbs -- and that's where the velocity requirements apply.

PD is more liberal than some companies in what they 'recommend'. That's due to canopy design in some cases (eg comparing to an old school Raven), while in other cases it may be just less conservative. (eg modern, heavy duty reserves like the Nano or Speed, having low 'maximum' weights if I recall correctly -- sorry no time to check manuals right now).

Some may call that 160 lbs the maximum, or maximum suggested or maximum recommended, or some other term, where each company has its own wording.

But the TSO weight (eg 220, 254, or 300 lbs) is the one that is the real weight that matters to the FAA. Isn't it?

You may be right, but I think the overall TSO weight mimnum (220 lbs for C23d) would put the PDR 99/PD Optimum over the limits for descent and total speed.

(found AS8015 here: http://avstop.com/ac/prh/appendixa_27.html)

4.3.7 states that descent rate shall not exceed 24 feet/s (~16 MPH), and total speed shall not exceed 36 feet/s (~24 MPH) in unaltered post deployment (brakes stowed).

It sounds like they got a waiver for that particular requirement for both PDR and PD Optimum. Icarus did not (though they may have gotten a waiver for minimum demonstrated weight).

From Icarus Reserve page: "The weights listed below are MAXIMUM weights required to comply with all certification requirements set under TSO C23d and ETSO C23d for minimum1 load and maximum allowable total velocity2."

[pchapman 261]

Good catch on the Icarus. Some other time I'll get back to this topic.

But for now: If we have to be asking these questions, it is an example of how the manufacturers haven't done a great job in explaining just what their certifications mean...

[gowlerk 1,901]

Have you read the PD reserve manual lately? It contains a fairly large section on what the certifications mean.

[billvon 2,379]

>Kinetic energy is still not all that is important.

Odd thing to say. Kinetic energy is what breaks your bones, and the amount of energy is often the difference between an injury and a fatality.

Note that kinetic energy is 1/2MV^2 - which means that it's made up of weight and speed. Eat a lot of burritos and double your weight and you'll have twice the kinetic energy to absorb on impact. But double your speed with a new canopy and you have _four_ times the energy to absorb.

[SethInMI 145]

gowlerk

Have you read the PD reserve manual lately? It contains a fairly large section on what the certifications mean.

I just read the manual section on certifications. It was not as clear as I wanted. I agree with shadeland, that it sounds like the waiver they talk about was to set a different max weight specifically for AS8015 section 4.3.7 descent limits (24ft/s and 36ft/s), instead of the 220lb min weight used for the other tests.

I would guess without the waiver small reserves would be un-certifiable, since they needed to pass the descent test with at least 220lb weight, and I am assuming a PDR-99 loaded at 2.22 would be descending faster than 24ft/sec.

In the PD manual, the charts starting at page 57 are interesting. For the PDR there are two weights, one the TSO max weight (for PDR-99 this is 220lb, the min allowed) and the other is a max weight of 119lb (for a wingload of 1.2)

For the optimum max weights there is the TSO, then some skill weights. OP-99 has a max TSO of 220lb, and skill weights of advanced 119 lb, expert 149, and max 220lb.

So why did they choose 1.2WL as the regular max weight? I assume that what is needed to satisfy the 24ft/s descent rate, but it is not clear. because if that was it, it should be referred to as TSO descent weight, or some such.

It does give me pause to see that for my PDR-143, the max weight is 171lb, so I am overloading at 200lb suspended weight.

Seth

It's flare not flair, brakes not breaks, bridle not bridal, "could NOT care less" not "could care less".

[shadeland 5]

Quote

So why did they choose 1.2WL as the regular max weight? is that what is needed to satisfy the 24ft/s descent rate?

Icarus pretty much says that on their Icarus Reserve page:
The weights listed below are MAXIMUM weights required to comply with all certification requirements set under TSO C23d and ETSO C23d for minimum(1) load and maximum allowable total velocity(2).
1) SAE8015b requires minimum weight to be demonstrated of 255 lb
2) SAE 8015b requires a maximum total velocity under open canopy of 36 ft/s


They're faced with somewhat incompatible (at least from a market perspective) requirements from a ram air persecptive: The minimum max load to be tested is 220 lbs, yet the total speed must be under 36 ft/s (25 MPH).

That probably makes sense for emergency round rigs, but with those requirements on a ram-air you wouldn't be able to have a canopy smaller than about 180 sqft.

Quote

It does give me pause to see that for my PDR-143, the max weight is 171lb, so I am overloading at 200lb suspended weight.

I show the max weight for a PDR-143 based on their site to be 200 lbs for expert (254 lbs do-not-exceed).

http://www.performancedesigns.com/products/pdreserve/

That would likely exceed 36 ft/s. By how much? I don't know. You're at 1.4 WL, which doesn't sound too crazy for a controlled landing. But a no-input landing might be different.

[SethInMI 145]

shadeland

They're faced with somewhat incompatible (at least from a market perspective) requirements from a ram air persecptive: The minimum max load to be tested is 220 lbs, yet the total speed must be under 36 ft/s (25 MPH).

It is interesting that they decided to split up the requirements, as I read it, you can't do that, the 220 lb test must pass all requirements, so it would not be possible to certify small reserves without a waiver of some kind.

I agree that does not make sense for ram airs, esp since wind speed makes groundspeed so variable, so I just want to know the descent rate. What is the glide ratio of a typical reserve with brakes stowed?

Regarding the max weight for my PDR143, the manual has not caught up with the website apparently, as it still shows a max of 171lb. I agree that is not unusual, still I wonder if my incapacitated stowed landing is survivable or not under it.

It's flare not flair, brakes not breaks, bridle not bridal, "could NOT care less" not "could care less".

[shadeland 5]

SethInMI

***
They're faced with somewhat incompatible (at least from a market perspective) requirements from a ram air persecptive: The minimum max load to be tested is 220 lbs, yet the total speed must be under 36 ft/s (25 MPH).

It is interesting that they decided to split up the requirements, as I read it, you can't do that, the 220 lb test must pass all requirements, so it would not be possible to certify small reserves without a waiver of some kind.

I agree that does not make sense for ram airs, esp since wind speed makes groundspeed so variable, so I just want to know the descent rate. What is the glide ratio of a typical reserve with brakes stowed?

Regarding the max weight for my PDR143, the manual has not caught up with the website apparently, as it still shows a max of 171lb. I agree that is not unusual, still I wonder if my incapacitated stowed landing is survivable or not under it.

This whole conversation started from someone saying that they believed the Optimums landed faster compared to other reserves. The original basis for that belief was that they learned form PD that PD had obtained a waiver from the FAA to allow a faster overall speed or descent speed.

I think the waiver probably came for a different reason, the reason we're discussing now.

I think that it wasn't the PD Optimums were faster, it's that under C23D there was that incompatability for ram air reserves. So I believe they obtained a waiver for both PD Optimums and PD Reserves, and the same is true for the other reserve manufacturers who tested under C23D (otherwise they could not possibly have C23D certified reserves under about 180 sqft).

Perhaps your reserve was an earlier version of the PDR that was tested under a different TSO? Or they just revised the speeds based on new information.

As to whether your landing would be survivable, I suspect yes in descent conditions (not downwind, clear and open field, dirt and not concrete), but I don't have really any basis for that other than eyeballing my approach speed on my Optimum 143 (WL 1.4). So my confidence is not high there. Though you'd probably break stuff.

[jurgencamps 0]

http://www.pia.com/piapubs/TSDocuments/TS-104CanopyVolume.pdf

Just for your information, a 170 canopy brand X or type X can be smaller than another 170 brand Y or type Y. There are several methods to measure a canopy. See the table in the link above for the "real" surface of canopies (all measured according the same method)

Also: PD always has "misnamed" their PDR reserves. They are in fact bigger than what the name suggests.
An optimum 126 = 126 square feet
A PDR 126 = 137 square feet.


In a presentation "dying for airspeed - Bryan Vacher"
http://www.skydivemag.com/article/dying-for-airspeed?fwd=1 you can find a table with horizontal and vertical airspeed.

Know that your airspeed is a combination of the horizontal and vertical airspeed http://www.beterrekenen.nl/afbeeldingen/driehoek_abc.png

For ex. if a skydiver with an exit weight of 90 kg / 200 pound, downsizes from a 170 to a 150, he (or she) will have + 23 % more kinetic energy when he hits the ground during a no-flare straight-in approach.

[Quagmirian 40]

jurgencamps

Also: PD always has "misnamed" their PDR reserves. They are in fact bigger than what the name suggests.
An optimum 126 = 126 square feet
A PDR 126 = 137 square feet.

Objection! PDs and Optimums are the same size. They're measured in the same way. And no, PD has not misnamed their reserves, they are exactly the size they are labelled, when measured by PD's method.

[shadeland 5]

Quagmirian

***

Also: PD always has "misnamed" their PDR reserves. They are in fact bigger than what the name suggests.
An optimum 126 = 126 square feet
A PDR 126 = 137 square feet.

Objection! PDs and Optimums are the same size. They're measured in the same way. And no, PD has not misnamed their reserves, they are exactly the size they are labelled, when measured by PD's method.

Their charts say otherwise:

PD Reserve - 143| Span: 16.27 Chord: 8.25 Aspect Ratio: 2.1:1 Sqft: 134.2
PD Optimum - 143| Span: 17.33 Chord: 8.25 Aspect Ratio: 2.1:1 Sqft: 143

It would seem an Optimum is slightly bigger than the PDR of the same model size, unless there's other reasons for the discrepancy.

The Optimums are pretty much 143 sqft by the math, while the PDR 143 is 134 sqft in the other direction of what Quagmirian said.

[shadeland 5]

shadeland

******

Also: PD always has "misnamed" their PDR reserves. They are in fact bigger than what the name suggests.
An optimum 126 = 126 square feet
A PDR 126 = 137 square feet.

Objection! PDs and Optimums are the same size. They're measured in the same way. And no, PD has not misnamed their reserves, they are exactly the size they are labelled, when measured by PD's method.

Their charts say otherwise:

PD Reserve - 143| Span: 16.27 Chord: 8.25 Aspect Ratio: 2.1:1 Sqft: 134.2
PD Optimum - 143| Span: 17.33 Chord: 8.25 Aspect Ratio: 2.1:1 Sqft: 143

It would seem an Optimum is slightly bigger than the PDR of the same model size, unless there's other reasons for the discrepancy.

The Optimums are pretty much 143 sqft by the math, while the PDR 143 is 134 sqft in the other direction of what Quagmirian said.

Running some of the other sizes is interesting. At 218 and below, and 113 and above, the sizes are identical, and the math works out. But for PDR, there's a bulge at 193 to 113 where they're smaller than the PD Optimum counterparts.

[pchapman 261]

Regarding weights allowed, Shadeland and SethInMI made some useful points.

The wording in the Icarus Reserve manual was mentioned, where as Seth said, they have the problem of having to test to at least 220 lbs, yet also have under 36fps total velocity. Are they allowed test for one but also add a lower weight limit to not exceed the other?

I made this post rather long but it shows some of the confusion about TSO's and wording. As I said before the industry in general isn't very clear on the rules.

The Icarus Nano uses some different language than was given for the regular Icarus reserves. One section says:

Quote

A wing loading higher than 1.325 lb/ft² is unsafe because of the high descent rate even with a fully deployed canopy. At this wing loading, the parachute cannot be expected to save your life if you are unconscious. Therefore, it is NOT allowed to fly in the wing loading range above 1.325 lb/ft².
According to the US FAA certification limits, it is forbidden to jump with this parachute with an exit weight exceeding 255 lb (116 kg).

Well, that's confusing. On what basis are they saying you can't use above 1.325? It isn't an FAA limit?

The Paratec Speed 2000 is similar in that it says what the FAA limits are (eg, 255 lbs) but then says never to exceed limits such as 176 lbs for the 135 size to assure safe flight and landing limits.

I don't know who actually follows these kind of limits. I remember back in the mid 1990s, the PD126 was a typical reserve for a hot, experienced jumper buying new gear. And that was for a jumper who might be 180 lbs without gear.

It isn't as if the manufacturer and USPA had some big campaign to warn that this was illegal.

Meanwhile, even their 2017 manual says that the PD-126R has a Max Suspended Weight of 151 lbs -- so it is really only suitable for 120 lb girls. Yeah, right, as if they're the only jumpers with 126's or smaller.

The manual also mentions "Max Suspended Weight (TSO)" and that's 254 lbs for the PD-126R.

In the section on wing loadings, PD mentions:

Quote

WING LOADINGS ABOVE 1.4 LBS/SQ.FT, AND BELOW THE MAXIMUM SUSPENDED WEIGHT:
This isavery highwingloading.Turnrates,forwardspeed andratesofdescentwillallbeveryhigh. A very high experience level is required to get an acceptable landing, even under ideal landing condi- tions.[...]While this is legal (if the conditionsbelowaremet), it is veryhazardous.

(Sorry for the bad formatting; it copied and pasted that way from the manual.)

It isn't clear which "maximum" they are talking about. Is it the 151 lbs for a PD-126R or the 255 lbs?
They do give an example of one of those charts with different experience levels, eg Intermediate - Advanced - Expert - Maximum. And that gives 254 lbs for the Expert for a PD-143R.
So that suggests the "maximum" is the TSO maximum.

They also provide some limitations like

Quote

At least 500 ram-air canopy jumps and at least 100 jumps on a ram-air canopy that is nomore than15%largerthanthereserveparachute

and then say

Quote

ThesearebothFAA(USA)andPerformanceDesignsrequirementsthatmustbemetforyoutobe legal.

So they seem to say that whatever their rules are in the manual, are the legal limits. But they don't state on what basis that is true, also leading to confusion.

It also therefore suggets that the "maximum" like the 151 lbs for the PD-126R, isn't the true maximum... if you do meet those other requirements, which they claim you have to follow... but without stating why.

They have a section on TSO C23... but there's almost nothing about C23d in that.

So we have PD saying that 255 lbs on a PD-126R is legal although under certain training requirements only, and certainly not recommended. So are they really claiming that that 2.02 wing loading (using their own 126 size rating, not the old PIA version of 137 or whatever) is actually legal for the total velocity requirement?

Now, the the PD was still under C23c for size 126 and up, but not the smaller versions and the Optimum. C23c doesn't have the total velocity requirement, only a rate of descent requirement, it looks like.

Even if that gets the PD-126R sort of off the hook, what about PD's C23d canopies? Is a PD-99R certified to 220lbs, really OK for C23d total velocity at a massive 2.22 loading? So what about those rumours of exemptions in their certification? One would expect that it would have to be mentioned if true. Or if not, how did their reserve pass the test but Icarus sucks and can't handle over 1.325, when they both are clearly modern designs?

And it isn't clear in the regs how a manufacturer can impose limits on what wing loadings different jumpers can use on their canopies. Is the canopy legal to the TSO values or not? AS8015B which is referenced by TSO C23d only refers to a single "maximum operating weight" -- the TSO weight. There's nothing in there about two different weights, a certified weight and another weight to satisfy manufacturer's preferences or total velocity requirements.

If it looks like I'm picking on PD, they still have the most extensive discussions of limitations that I've seen.

In the end we're stuck with the issue that it looks like PD allows very high wing loadings (although very reluctantly), while other companies tend to prohibit very high wing loadings (while not quite saying why that might be a legal prohibition).

[jurgencamps 0]

Quagmirian

***

Also: PD always has "misnamed" their PDR reserves. They are in fact bigger than what the name suggests.
An optimum 126 = 126 square feet
A PDR 126 = 137 square feet.

Objection! PDs and Optimums are the same size. They're measured in the same way. And no, PD has not misnamed their reserves, they are exactly the size they are labelled, when measured by PD's method.

And how come that PIA measures different sizes when they use their "standard" measuring method?