PD Reserve versus PD Optimum Forward Speed

[shadeland 5]

I've heard this a few times: PD Optimums, despite being a size bigger, have roughly the same forward speed as a a PDR one size smaller, negating most of the benefit of having a larger reserve for unconscious/no input landings.

Example: A Optimum 160 would land about as hard as a PDR 143 (the next size down).

I've heard that from a few riggers, but I haven't seen any data to support that. I've got two rides on an Optimum 143, but of course I don't have anything to compare it to (or quantitative data).

Does anyone have any data to support or refute this? Is this one of the factesque things that gets widely reported and thus taken as fact?

Can someone from PD chime in?

"It's been widely report John, and that makes it fact-esque" -Stephen Colbert.

[gowlerk 1,914]

I can't really answer that question. But I can make a relevant comment. It's not so much the forward speed, but the total speed that matters. That is to say the downward speed plus the forward speed is the total speed you are moving. And that speed is different with the brakes stowed versus unstowed.

Probably the only people who can answer the question are the people who did the testing. And I'm guessing they will not say.

[shadeland 5]

gowlerk

I can't really answer that question. But I can make a relevant comment. It's not so much the forward speed, but the total speed that matters. That is to say the downward speed plus the forward speed is the total speed you are moving. And that speed is different with the brakes stowed versus unstowed.

Probably the only people who can answer the question are the people who did the testing. And I'm guessing they will not say.

I should have been more specific, but yeah I mean forward/descent speed. Impact speed, essentially.

I'd be willing to hook one of each up for a test jump.

[sundevil777 93]

I would think that rate of descent would matter more than forward speed in an unconscious scenario, therefore total speed doesn't tell you all of what you are seeking.

Also, speed with the brakes stowed is what matters for your scenario, and what you've heard may not have that in mind. I would not trust at all what you've heard, unless it came from people that are involved with the mfg.

It is quite easy to find people that think they know everything. They are really irritating to those of us that do.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[JerryBaumchen 1,048]

Hi Cliff,

Quote

I would think that rate of descent would matter more than forward speed in an unconscious scenario

I'm glad that you only 'think' this.

Having had the opportunity to watch nearly an entire series of tests for TSO certification ( except for the strength tests & the live jumps) from the ground and using only round canopies vs later watching multiple series of square reserve canopies land during testing, I disagree. The impact forces IMO ( not a measurable event for certification ) are far greater with a square canopy going downwind.

Jerry Baumchen

[rmarshall234 13]

>The impact forces IMO are far greater with a square canopy going downwind

Sadly, we had a jumper at Brown Field several years ago make this exact point.

Mitch Murphy downwinded his ram-air in high winds and died from a broken neck. He was a good guy too.