Proposition - new tech spec for reserves

[MartinOlsson 0]

One relevant factor when I'm shopping for a new reserve is if said reserve give me a reasonable chance to survive if I were to land it without any input. So far the only data you could use to decide this is size. But since manufacturers choose to measure differently and use different brake settings it is really hard to determine how rough a no input landing would be.

Why not state which decent speed a canopy have at an 1:1 loading in the braked setting? Is there any good reason why this is irrelevant or not feasible?

/Martin

[KellyF 16]

There are maximum velocities specified in TSO C23D and the upcoming -E. To keep things simple, get a 23D reserve and stay within the weight limitations

VSE on Facebook

[MartinOlsson 0]

What are the maximum velocity in 23 D and E?

/Martin

[DSE 5]

Speed would be relevant to wind in addition to wingloading, and a no-input landing would likely be downwind, right?

I'm told the reason the US doesn't have wingloading requirements tied to licenses is the legal aspect. If so, wouldn't this data be cut from the same cloth?FWIW, I've seen one no-input landing under a .8:1 reserve (skydiver lived with broken face, radius/ulna, tib) and a video of a no-input landing under a 1.3:1 (skydiver didn't survive). both were very high speed, and not sure how any of that data could be accurately presented and avoided as information in a lawsuit?

[DanG 1]

Quote

a no-input landing would likely be downwind, right?

Oh God, not this debate again. Please.

- Dan G

[riggerpaul 1]

Quote

Quote

a no-input landing would likely be downwind, right?

Oh God, not this debate again. Please.

Doesn't really have to be that debate again.

If using 45 degrees to either side of the wind as "into the wind", there's still 3 to 1 odds that you will not be "into the wind" if there's no control input, right?

Couldn't that be the point of the statement "likely to be downwind"?

[phoenixlpr 0]

Quote

Speed would be relevant to wind in addition to wingloading, and a no-input landing would likely be downwind, right?

Your canopy flies in the air. How can you tell without any reference like the ground which way is downwind?

[riggerrob 643]

A no-input landing could be in any direction.

Let's clear up the superstition about canopies automatically turning down-wind.
Most canopies have built-in turns, especially if the user is hanging limp (leaning sideways) in the harness.
Any canopy will slowly turn cross-wind, then turn down-wind, then turn cross-wind, then turn into the wind, then turn cross-wind, etc.
It is pure luck which way the canopy is facing when it lands.
Granted, landing down-wind is harder on the body than landing into the wind, but another major factor is the angle of impact. Ram-air canopies tend to land with a shallow, glancing blow, which vastly reduces compression fractures of the spine. Just ask any POPS who remembers backwards PLFs under round canopies.

[GLIDEANGLE 1]

TSO-C23d specifies that the standards in SAE AS8015 REV. B must be met. The relevant section of SAE AS8015B is §4.3.7. A copy of that section is attached.

As I understand it, TSO-C23e is likely going to specify compliance with PIA TS-135. I have attached the relevant section from PIA TS-135 Revision 1.1, Issued 19 February, 2008. I don't believe that this is a done deal yet. I seem to recollect that there was more work to be done before TSO-C23e will be final.

The choices we make have consequences, for us & for others!

[DSE 5]

Quote

Quote

Speed would be relevant to wind in addition to wingloading, and a no-input landing would likely be downwind, right?

Your canopy flies in the air. How can you tell without any reference like the ground which way is downwind?

I'll reply with my limited experience.
Of the two no-input landings I've witness (both skydivers not conscious), neither were upwind. one was straight in; according to the video winds were around 15. The other had a slow turn but moving overall in a downwind direction, landing in the slow spin was crosswind. Both had a relatively high ground speed. Scott's death wasn't caused by the high speed landing, but it contributed to his already damaged body.
I didn't mean to imply that any skydiver who is unconscious will automatically land downwind, but rather in the direction the wind is moving.
However, would a wingloading chart that could improve the odds of safety in an unconscioous or no-input couldn't be counted on for accuracy in a real world situation, could it?

[MartinOlsson 0]

Quote

However, would a wingloading chart that could improve the odds of safety in an unconscioous or no-input couldn't be counted on for accuracy in a real world situation, could it?

I'm actually not that interested in absolutes. What I'm aiming at is how different brand reserves could compare in terms of speed in a braked setting. Hypothetically a 113 reserve could be better in a no input situation than a 143, if it has a much deeper brake setting than the 143. It could be interesting to know if the big reserve I'm buying actually is faster in a braked setting than a smaller one of a different model.

/Martin

[phoenixlpr 0]

Quote

Quote

However, would a wingloading chart that could improve the odds of safety in an unconscioous or no-input couldn't be counted on for accuracy in a real world situation, could it?

I'm actually not that interested in absolutes. What I'm aiming at is how different brand reserves could compare in terms of speed in a braked setting. Hypothetically a 113 reserve could be better in a no input situation than a 143, if it has a much deeper brake setting than the 143. It could be interesting to know if the big reserve I'm buying actually is faster in a braked setting than a smaller one of a different model.

/Martin

How about the rate of descent? My guess is 143 would have a flatter glide, so shallower angle of attack on impact on same WL.

[JerryBaumchen 1,445]

Hi Dan,

Quote

Oh God, not this debate again. Please.

Oh, why not; it is sooo muuuchhh fuuunnnn.

I have done some drop testing of square reserves using a dummy ( no, I was not the dummy ). In every drop the canopy turned downwind.

Here are some thoughts of mine ( just in the small chance that anyone cares ). If you were to drop a sphere that is perfectly balanced it would not turn in the wind because it is exactly equal in every manner. A square canopy is not symmetrical; take a look at the profile of any of them. Also, the are not the same when viewed from the front vs the back. IMO ( yup, here it is ), the wind forces are the canopy are simply not the same as the wind passes over & around the canopy. That is why it will turn downwind; it will always want to go the way of least resistance.

Based upon the testing that I have performed, it seems as though the path of least resistance is downwind. It is called Physics.

Other than that, it is as Rob says, due to a harness shift, etc.

Just my old $0.02,

JerryBaumchen

[peek 21]

Quote

I have done some drop testing of square reserves using a dummy. In every drop the canopy turned downwind.

As we say in the PCPRG, "One test is worth a thousand opinions."

Quote

If you were to drop a sphere that is perfectly balanced it would not turn in the wind because it is exactly equal in every manner. A square canopy is not symmetrical; take a look at the profile of any of them.

One reason people have difficulty with this is that they assume that an object in the wind is going the same speed as the wind. Would a feather be at the same speed? No arguments there. Would a helium balloon? Pretty damn close. But would a parachute with a load? Nope.

Also, the heavier the object, the longer it takes to get to approximately the speed of the wind (equilibrium). During this time, the speed differential is even greater that before it reaches its equilibrium, and it is during this time that much of the downwind turning will occur.