New AAD made in USA

[pchapman 261]

df8m1

I have no idea why anyone would turn on their AAD and drive to the DZ, but they do..

Well ya never know. Although I was thinking of the more common situation of an off-landing retrieval, where the land isn't perfectly flat. (Although the cure for uncertainty there is just to cycle the AAD off and on...)

[pchapman 261]

df8m1

Where I get uncomfortable is the touchdown aspect of the flight.

That's a phase of flight that if I recall correctly has set off AAD's of different types with no authoritative explanation why. We've sometimes heard ideas kicked around that sound plausible but who knows.

In particular, the idea of the swooper losing speed during the pullout & planeout, results in a lessened burble, which equals a suddenly increasing pressure which equals a sudden drop, activating the AAD. Or it could just be the AAD reacting to a high dive speed in the middle of the swoop but taking a little while to filter & confirm the speed before popping the reserve pilot chute, which then appears when the swooper has partially planed out.

Various aspects of those scenarios are debatable. But I've still never seen a good explanation of such situations. So that last hundred or few hundred feet of altitude is a bit mysterious....

[df8m1 19]

pchapman

***Where I get uncomfortable is the touchdown aspect of the flight.

That's a phase of flight that if I recall correctly has set off AAD's of different types with no authoritative explanation why. We've sometimes heard ideas kicked around that sound plausible but who knows.

In particular, the idea of the swooper losing speed during the pullout & planeout, results in a lessened burble, which equals a suddenly increasing pressure which equals a sudden drop, activating the AAD. Or it could just be the AAD reacting to a high dive speed in the middle of the swoop but taking a little while to filter & confirm the speed before popping the reserve pilot chute, which then appears when the swooper has partially planed out.

Various aspects of those scenarios are debatable. But I've still never seen a good explanation of such situations. So that last hundred or few hundred feet of altitude is a bit mysterious....

Sorry for not properly addressing your comment on the AAD being turned on at another location. Your second comment on a different landing elevation is valid and not a problem. Even if the drive is up a really steep and long hill at high speed, which could cause the this AAD to stop updating the Ground Level Reference Pressure, the conditions required to put it into Airplane Mode would be, I won't say impossible because there is always someone up to the challenge lol, but it would be a Pikes Peak drive to do it.

Now if the Airplane Mode requirements are not met in a period of time, then it will resume updating the Ground Level Reference Pressure, which will adjust the ground pressure to the current location. In theory all AADs should do this, but I suspect that some don't do it very well.

I just do not want to say, "with this AAD you can do X which you should have been trained not to do".. The more we overcome stupidity, the dumber people get lol..

To your comment on the 100ft disarming...

There is indeed something different about the last 150ft (ish) depending on temperature and humidity. We have data from a near terminal fatality and the density right of the ground is very different than say above 150. Without question, the last 50 feet is different.. That change in consistency lets call it, can really cause a change in what the AAD perceives compared to what the jumper is really doing..

I have had more time to think about why I feel the need to have a hard disarm altitude, (I have never thought about why, as it makes sense to me lol) and have found some additional benefits aside from the very challenging and inconsistent conditions that can exist during the final phase of landing.

Every algorithm has to be able to be tested individually, and when nested with others to work in a phase of flight. I would have to create a new matrix just for the landing phase which would be very challenging and IMO provides no benefit to the jumper at that point in the flight.

That being said, the digital testing could be developed and done, but then comes the field testing.. We use drop test dummies to test the firing algorithms in the air. We will use dummies on the front of a tandem and cut them away to simulate a cutaway at different altitudes, and pitch them out above 1250ft while rigged to fall at different rates to test out the firing altitude calculations and firing command algorithms.. We would have to do the same thing with the landing phase if the AAD were still armed at that point..

Additionally, having a well defined arm and dis-arm points makes a nice little box with limits that I can test beyond to see if something happens when it should not.

I am glad I was challenged on it, and think that bringing down the disarm altitude to 100/150ft is a reasonable compromise as it still provides me what I want, and if it makes some jumpers happy, then it is a win win.

There are several things that I have done based on data that we have, like the landing anomalies, that is not common knowledge. Even though I am not providing all the details as to why I am doing what, I think I can say that this level of access during the development of an AAD is unprecedented lol.. and I think it will result in a better product..

After the last conversations, I am now questioning if it should display the calibration pressure, because some nitwitch will compare it to a barometer that is not certified or has not been calibrated ever and will freak out because the two readings don't match. They wont trust that the error detection will catch a problem but will trust the $.99 dollar store barometer lol.. It is like displaying the battery voltage, causes nothing but trouble..

[df8m1 19]

So I have a minute and thought I would post an update. We had what seems like our last really nice weekend a couple of weeks ago and I was able to get a few jumps in with the new AAD. Special thanks to Skydive Tecumseh for their indulgence and help.

This was the first time a prototype has been off the bench and out in the field and it is very obvious that the interface screen will not cut it. I is very visible until it gets out in natural light lol... One of my team members said that if this is the biggest problem we have we are doing good and I agree with him..

No matter how much testing we can do on the bench, there is only one way to know what something is going to do in the air, so you have to jump it. We discovered a OS problem that showed up after the first jump. It actually would only show up after the first jump each time it was turned on, and affected the data recording process.. It was a simple fix, and is part of the validation process.

I was really pleased with the data that was recorded. I am making refinements to the flight mode and firing algorithms and am very happy with how they are working. There is always room for tweaks here and there lol...

I was most pleased with the altitude readings taken by the sensor in the interface. I am waiting to see what it looks like with a wingsuit, but I am leaning toward not "correcting" the altitude, from the interface anyway, as it really was a lot better than I had expected. Now the "black box" pressure varied like I expected it to, but it is not used as the primary sensor for this application. Not having to correct the altitude eliminates some complexity, and I am all for that!

We will be jumping when and where we can over the winter collecting more data and dialing this thing in. We will also be pitching out dummies with a live AAD when we can. The Army wants 45 sequential successful drops using 250 lb dummies and I can't say I am looking forward to that... It is a lot of work lifting those things! lol.

Oh! we also are looking to test in a vertical and horizontal wind tunnel which should be fun.

That is all I have for now.

[piisfish 135]

When you test jump your AAD, do you actually have another AAD in your rig ? I suppose the tested device is not actually “active “, but rather in an outside pocket.

scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

[df8m1 19]

piisfish

When you test jump your AAD, do you actually have another AAD in your rig ? I suppose the tested device is not actually “active “, but rather in an outside pocket.

It is packed up in the reserve properly, but the loop is not through the cutter, instead the cutter is super tacked to the cutter bungie so it wont go anywhere or be able to cut the loop, but is there as a static antenna lol..

We wont go live on a jump with a real jumper until we are in Beta. Luckily there are some brave dummies who get to do the first live drops :)

I am using the data collected by the actual device while packed up in a reserve so I can run it through the simulation and optimize the algorithms and settings.

When we get to the Beta phase, the first units that we send out to the test jumpers will have the fire controls turned off, and cutters with a hole only in one side of the cutter, and the "blade" will be a slug so to speak. The purpose is to allow a visual inspection of the piston to see if it had fired from static, but will not allow a rigger to put the loop through the cutter.

This is why I will only consider test jumpers who do not have an AAD in their rig. Once we get the wingsuit, and swoop data and validate the algorithm settings with it, and we have verified proper operation using dummy drops, we will send out units with active fire controls and real cutters... If the jumpers want to jump them at that phase that is :)

If you are asking me if I have an Active AAD in my test rigs? The answer is no.

[df8m1 19]

Prototype cutter blades ready to be hardened, then the cutting edge lapped. I would like to do some cutter tests later next week.

Note: the blade on the right is a Cypres cutter blade for reference.

[skydiverek 54]

df8m1

Prototype cutter blades ready to be hardened, then the cutting edge lapped. I would like to do some cutter tests later next week.

Note: the blade on the right is a Cypres cutter blade for reference.

Make sure it is hard enough. Argus' blade was not... See the whole report (in English) here:

http://mib.gov.pl/mediakomisje/archiwum/2009562RKPKBWLang.pdf


.

[df8m1 19]

skydiverek

***Prototype cutter blades ready to be hardened, then the cutting edge lapped. I would like to do some cutter tests later next week.

Note: the blade on the right is a Cypres cutter blade for reference.

Make sure it is hard enough. Argus' blade was not... See the whole report (in English) here:

http://mib.gov.pl/mediakomisje/archiwum/2009562RKPKBWLang.pdf


.

Very aware of the Argus cutters. The Argus blade design, (cylindrical), and the large hole in the cutter body allowed the grommet to drop down into the cylinder, so the blade would strike the grommet before the loop. That type of blade edge is very thin and delicate, prone to bending.

My blades are made from 440C Stainless and hardened to RC 58-60. The blade design is the same as chisels which are made to cut by blunt force.

One of the tests I would like to do is to thread a loop through the cutter, suspend the cutter in a container and fill it with steel shot so the cutter is buried, then fire it.

I have no expectations for this test, purely curious to see if the blade will push the shot out of the way and cut the loop. This test will be conducted within a bullet proof enclosure in case things get interesting.. Safety first....

[mxk 1]

I would be curious to see a test where you try to cut an untensioned closing loop. Cutting a loop under tension is much easier. This test would simulate what may happen if the cutter fires a split second after the pin is pulled by hand or RSL.

[mark 102]

df8m1

Very aware of the Argus cutters. The Argus blade design, (cylindrical), and the large hole in the cutter body allowed the grommet to drop down into the cylinder, so the blade would strike the grommet before the loop.

IIRC, the problem manifested when the closing loop did not go straight through the cutter. The blade would first strike the top (or bottom) side, causing it to tumble slightly, then jam on the opposite side because of misalignment.

For Argus, the size of the hole compared to the diameter of the cutter body is not that different from Cypres and Vigil cutters. I do not recall a grommet strike being identified as an issue in any of the problematic incidents.

-Mark

[LeeroyJenkins 2]

df8m1

Prototype cutter blades ready to be hardened, then the cutting edge lapped. I would like to do some cutter tests later next week.

Note: the blade on the right is a Cypres cutter blade for reference.

Out of curiosity, why did you make you cutter so much bigger than the cypress cutter, while what looks like maintaining the same minimal cross sectional area?

[df8m1 19]

mxk

I would be curious to see a test where you try to cut an untensioned closing loop. Cutting a loop under tension is much easier. This test would simulate what may happen if the cutter fires a split second after the pin is pulled by hand or RSL.

All tests will be at zero loop tension. A consistent, clean cut is the requirement with the loop just laying in the cutter.

[df8m1 19]

mark

***Very aware of the Argus cutters. The Argus blade design, (cylindrical), and the large hole in the cutter body allowed the grommet to drop down into the cylinder, so the blade would strike the grommet before the loop.

IIRC, the problem manifested when the closing loop did not go straight through the cutter. The blade would first strike the top (or bottom) side, causing it to tumble slightly, then jam on the opposite side because of misalignment.

For Argus, the size of the hole compared to the diameter of the cutter body is not that different from Cypres and Vigil cutters. I do not recall a grommet strike being identified as an issue in any of the problematic incidents.

-Mark

There was another incident here in the USA where the Argus blade hit a grommet and failed to cut the loop. As I recall, there was a witness mark on the grommet that was on top of the cutter. Kirk Smith of Para Concepts did some independent tests and reproduced the blade strike failure. His report is on line somewhere.

[df8m1 19]

LeeroyJenkins

Out of curiosity, why did you make you cutter so much bigger than the cypress cutter, while what looks like maintaining the same minimal cross sectional area?

A larger diameter at the same pressure generates more force. From a failure mode aspect, if the pyro cartridge should, for some reason, not generate full pressure, or one of the seals fail, I want to have some margin built in. It will be interesting to see how low the pressure can be and still cut the loop at zero loop tension.

It also allows for larger seals to be used. I am using quad rings instead of traditional 0-rings. Some of the tests will be done with only using one seal.

[LeeroyJenkins 2]

df8m1

***Out of curiosity, why did you make you cutter so much bigger than the cypress cutter, while what looks like maintaining the same minimal cross sectional area?

A larger diameter at the same pressure generates more force. From a failure mode aspect, if the pyro cartridge should, for some reason, not generate full pressure, or one of the seals fail, I want to have some margin built in. It will be interesting to see how low the pressure can be and still cut the loop at zero loop tension.

It also allows for larger seals to be used. I am using quad rings instead of traditional 0-rings. Some of the tests will be done with only using one seal.


Ah, yeah. I figured it was o-ring related. Those things are annoying to engineer

[df8m1 19]

Finally got a chance to play with the cutter. DZ.com only allows a max of 1Mb file and I was able to shorten the video but it is really quick!

139_cut.avi

[EnricoPalazzo 1]

Do you have some other views?
A schematic perhaps?
It seems to cut loop nicely, but not much to see from the top-down video...

[df8m1 19]

So far that is the only video that I was able to get bellow 1MB that showed anything lol..

What is it that you specifically want to see that this video does not show?

[EnricoPalazzo 1]

Just curious how the cutter is designed. Is it similar to the Cypres unit? Also in the firing mechanism using a chemo-electric capsule?
That's the only one I know, but I'm curious to see if there is a better way to cut the loop.

[df8m1 19]

Gotcha.. Yes, it is a single edge cutter like the Cypres and I also believe that MarS is now using a single edge cutter as well.

I posted picks of my blade a few posts back. Also using a standard gas generator for power just like the other cutters out there.

My cutter has some features that are different than the Cypres cutter, they are minor, but were done for a reason.. I will get more into that in time.

[skydiverek 54]

df8m1

So far that is the only video that I was able to get bellow 1MB that showed anything lol..

What is it that you specifically want to see that this video does not show?

Please upload a FULL HD video to YouTube, or to some other free video website.


.

[df8m1 19]

At some point I will. With this first batch of cutters I was testing different cylinder materials, and loop hole / grommet face geometry, but the cutting aspects were the same (same blade material, hardness and geometry).

For some tests, I turned the blade as much as 30 degrees off perpendicular to the loop, some the loop holes were in slightly different places / sizes, etc.. The last version (not in the video) was shaped to help with rigging.

My intent was to reuse the blades, but it is too much of a PIA to get them out once they are fired lol.. The blades hold up well. If I think about it I will take a picture of a used blade.

Now that I am happy with the cylinder material and, internal / external aspects, I will make more blades and cylinders based on the last design, and evaluate overall performance in a rig. I will also make more videos from different angles, put them together and up load them to YouTube. I just thought people would appreciate a sample vid.

[df8m1 19]

Attached are three pics of a fired blade and anvil. Anvil material is 17-4 SS at 34Rc. Blade is 440C SS at 58Rc.

Also a pic of an assembly view of the finial design cutter and a pic of the body by itself.

[377 20]

Fascinating posts, especially for us engineer-jumpers. Designing an advanced tech AAD is damned complex, far more than I had realized. Things have come so far since the SSE Sentinel days.

The market is small, the product liability risk is high and no matter how well you design it, users will inevitably ignore instructions, install it wrong, skip scheduled maintenance etc. Plaintiff's lawyers will sue you regardless of liability releases, user error and lack of product defect.

Sure glad somebody is willing to take AAD design to the next level. I wish them the very best and look forward to becoming a customer.

377

2018 marks half a century as a skydiver. Trained by the late Perry Stevens D-51 in 1968.