New AAD made in USA

[GoneCodFishing 23]

I may be about to say something very stupid... but assuming the cutter is rigger replaceable, couldn't it be disconnected, feed the jack through the elastic and run through the cable until the cutter unit goes all the way to the hilt in the elastci, and then just reconnect it to the main unit?

It kind of sounds like the simplest solution, which is why i think i must be missing something...

[gowlerk 1,902]

GoneCodFishing

I may be about to say something very stupid... but assuming the cutter is rigger replaceable, couldn't it be disconnected, feed the jack through the elastic and run through the cable until the cutter unit goes all the way to the hilt in the elastci, and then just reconnect it to the main unit?

It kind of sounds like the simplest solution, which is why i think i must be missing something...

I think he was already suggesting that. To look at the pics it is not that different from the M2 design. The holder is made from elastic and I suspect it will fit, but not easily. A little more taper at the end, and it will probably work in most applications. Maybe some KY jelly?

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

[GoneCodFishing 23]

Ah, gotcha. I thought he meant rounding off the top corners and using a hood to feed it through the normal way, but reading it again you are right.

[pchapman 261]

df8m1

This cutter has a larger loop hole than the Airtec cutter as well as a larger blade piston (single edge V). I need some wall thickness at the end for a blade locating pin

May I ask, how do you get around the Airtec cutter patent? But it has been a while so is it still in force?
I haven't tried to read up on the issue but as skydivers we always were used to the Airtec single blade while 'everyone else ended up using a circular cutter'.

[councilman24 36]

pchapman

For everyone comparing cutters, we clearly need to whip out the M2's flat sided cutter as well. A pic from the web is attached.
(From a review of the M2 at skydivenow.co.uk )

I didn't take time to compare to the new flyer but M2 cutter will be going to axe head type and shorter cylindrical portion with the new changeable this summer. If this is the current/old one then the measurements are longer than the new one.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[df8m1 19]

pchapman

***
This cutter has a larger loop hole than the Airtec cutter as well as a larger blade piston (single edge V). I need some wall thickness at the end for a blade locating pin

May I ask, how do you get around the Airtec cutter patent? But it has been a while so is it still in force?
I haven't tried to read up on the issue but as skydivers we always were used to the Airtec single blade while 'everyone else ended up using a circular cutter'.

Thanks for the pic!!

All the early Airtec patents have expired. Even M2 has abandoned their version of a cylindrical blade in favor of a single edge V-blade.

Although there are single edge blades used in commercially produced cutters, most use a cylindrical blade. They mostly are cutting wires or other material that sheers well. The problem is the material that is used for AAD closing loops does not sheer well at all.

I decided to control the cylinder and blade assembly in house and have the pyro cartridge made by a commercial cutter company. The cutter is very special to our application and so much depends on it working properly that I do not want to risk outsourcing it.

I had mentioned turning down the diameter of the head that makes up the corners in an effort to see if it would pass through the elastic, but I really want to maintain as much of the flat face as possible. I think feeding it through backwards will be the way it will have to be installed. But as I said, lets modify it and see what we get.

I will post a pic after I get it cut down.

[JerryBaumchen 1,046]

Hi Dave,

Quote

I really want to maintain as much of the flat face as possible

One thought comes to mind of a 1/2 circle cross-section; flat on the bottom & round on the top. This would remove a fair amount of the area & keep the flat face as you want.

Jerry Baumchen

[skydiverek 54]

Things to avoid, in order not to repeat the history:

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

and

www.pia.com/TechnicalArgusDocuments/ARGUS%20Cutter%20Review.pdf

and

the attached files.


.

[Deimian 43]

df8m1

I do have something that I would like to ask the readers…. Although I have been trying to keep the design as compatible with the 25 year old AAD box and cutter retainer elastics, as well as the Interface window, I do not limit the design to them. The first thing that Todd (our rigger) said when he saw the head of the cutter body is “that wont fit through a cutter elastic”… and I said then change the elastic.. lol.. During the AADvance seminar a rigging question was asked and Todd answered that at one time no container was set up for an AAD and that the pockets and windows had to be installed by a master rigger. The AADvance AAD is designed to perform in all the flight modes from exit to landing on every jump. If in order to benefit from that level of performance, an elastic pocket or loop needs to be changed, then I think that is a small one time incontinence that at an earlier time was just the way it was if you wanted an AAD in your rig.

I am reading this as: "the box might have different size requirements than other AADs". One thing you might consider is that if it is significantly more bulky, it won't fit in many containers whose reserve tray is already maxed out.

df8m1

I just do not think that the advancement of new technology should be dictated by the carryovers of the old.

I partly agree. Sometimes, a revolutionary design is not backwards compatible. The question is if the benefits in real life are big enough to justify breaking compatibility. Backwards compatibility is a big part of the reason why some companies outperform their competition with inferior designs. Intel's big advantage 15 or 20 years ago was that everything worked with their processors, whereas for newer and more advance designs -from their competitors-, a lot of reengineering was necessary. Most of their competitors are now dead. Backwards compatibility shouldn't be underestimated.

[mxk 1]

df8m1

I think feeding it through backwards will be the way it will have to be installed. But as I said, lets modify it and see what we get.

Remember that it's not just the elastic that it needs to go though. On my Vector, the nylon ripstop channel that routes the cutter cable along the edge of the first flap is barely wide enough for the Vigil cutter. If I tried to feed the cable backwards, I'm pretty sure that the connector would not fit through this channel.

[df8m1 19]

I will reply in order of posts.

Jerry,

That is a thought… I spent some time playing with different ways to get the flats I want while maintaining the max diameter comparable to the other cutters and I think this is one battle that I can not win lol…

Skydiverek,

When we were testing the deployment set up on the test rig we used an Argus cutter that I got when I picked up an Argus to look at. It did not cut the loop clean. The reason I went with a single edge blade is after 20+ years, it has proven to work the best with the material that is used for reserve closing loops.

Deimain,

My mantra is better living through modification lol… If I don’t like how something is, I take it apart and modify it. The flats are addressing my personal concerns, not an identified problem, and based on the feed back (which I am grateful for), and my responsibility to my investors, I will yield my position and fall back to a traditional and compatible design. I made a quick mock up and took a pic of it amongst the other cutters. I found a Vigil cutter so I added it to the line up. One of the attached pics is the cutters, the top is a Argus cutter, the second is my first concept with flats, the third is the new mock up that is comparable to the traditional cutter design, the fourth is an Airtec cutter and the fifth is a Vigil cutter.

My new mock up cutter body diameter is the same as the largest diameter on all the other cutters. They all have a diameter of .345 +- .005 inches at some point along the length of the body. The entire length of the new body is .345 inches in diameter. I reduced the loophole diameter to .150 inches, which is consistent with the Airtec cutter. A smaller hole reduces the ability of a grommet to lock into the hole.

I also have attached some pics of the control box next to a Cypres 1. It is a little wider than a Cypres 1, about the same length as a Vigil II and about half the height of a Cypres 1. I have a shorter antenna coming and I think I am going to bring the connectors in closer to the body.

This is as compact as I could get it and still have the battery capacity and board space needed to do the job. It does fit in a Cypres pouch but it sticks out just a touch.

MXK,

My connector is an M-8 so it is bigger than a Vigil connector so that is one more reason to fall back to a more traditional and more importantly, proven design.

[skydiverek 54]

This issue with Argus blade was (also) that it was made from too soft material. The English report details it. It is linked few posts above by me.

[gowlerk 1,902]

Quote

It does fit in a Cypres pouch but it sticks out just a touch.

Not all containers use the CYPRES pouch. UPT for one uses a Vigil pouch and it is not the same dimensions. MarS also makes pouches. While your design does not seen to be larger than existing ones in overall size, it is larger in the worst possible way, width. This could become an issue in some smaller rigs. Sticking out the end a little should not be too much problem. But being so wide that it fills the available space could make it vulnerable to physical damage when Joe cool small rig skydiver drops it on the packing mat.

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

[df8m1 19]

gowlerk

Quote

It does fit in a Cypres pouch but it sticks out just a touch.

Not all containers use the CYPRES pouch. UPT for one uses a Vigil pouch and it is not the same dimensions. MarS also makes pouches. While your design does not seen to be larger than existing ones in overall size, it is larger in the worst possible way, width. This could become an issue in some smaller rigs. Sticking out the end a little should not be too much problem. But being so wide that it fills the available space could make it vulnerable to physical damage when Joe cool small rig skydiver drops it on the packing mat.

The Black Box is less than ¼ inch wider than the Cypres 1 (.200 inches wider to be exact)

The dimensions of the box are the result of many revisions in an effort to maximize operational capability and keep the size to a minimum. As the saying goes, “it is what it is”.. lol.. This is one area where I am ok with it possibly not being compatible with a certain percentile of containers, but I think it will be fine as long as they do not have to shoe horn the reserve in there because they want the smallest rig.

The box is made from 2024 aluminum so it is pretty darn tough, but that is not to say it is indestructible. Jerry doesn’t like the corners, he wanted them more rounded, and I do not disagree that that would be nicer, but they are necessary and serve the function of allowing area for the battery cap screws to thread into, and it gives me more usable room in the ECM cavity.

It is the batteries that are controlling the width. There are three ER18505M cells in there side by side. If we have to have our own pouch then that is not the end of the world. To the point that some cutter piping and elastics are a PIA to change, I backed off of the cutter design that I really would prefer, but I do not have any room to move on the black box. This is a Military AAD, designed to withstand the requirements of the military, now that is not to say that someone some where has so little respect for their live saving equipment that they will drag it across the tarmac and throw it to the ground as hard as they can. That is the kind of thing that we are looking for in the Beta testing lol.

Your concern is valid, but do you think that a difference of just over 3/16 of an inch are going to make that much of a difference? And our box is tuff aluminum, not plastic. But to your point, the new wingsuit rigs did look thin…. Small steps..

Skydiverek,

The blade in our cutter is made from 440C Stainless Steel hardened to 56-58 Rc. The body is made from annealed 17-4 Stainless Steel. We also are using quad ring seals instead of O-Rings as they seal better under pressure than an O-Ring. They offer the performance of an O-Ring and a Lip Seal, where the seal quality increases as the pressure goes up.

[gowlerk 1,902]

Quote

Your concern is valid, but do you think that a difference of just over 3/16 of an inch are going to make that much of a difference? And our box is tuff aluminum, not plastic. But to your point, the new wingsuit rigs did look thin…. Small steps..

Possibly not. I can't really tell without trying it. But I do note that when Airtec redesigned the CYPRES into the new model they made it narrower. I believe their original battery selection was also the reason for the form used.The original CYPRES was already a little too wide for the pouch.

It will probably work alright in almost all applications. I only mention it because it is not the ideal. But all design involves compromise, and good batteries are important.

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

[df8m1 19]

I thought I would post an update as it has been a while.

The Rev-A prototype is packed up in our test rig and weather permitting I will be jumping it on the 7th.

Even though I have set artificial timelines for specific phases of the development process, the determining factor has always been performance and quality, as I have said before; the AAD will determine when it is ready for release, not a date on a calendar, and I am pleased with the results of this philosophy. My team is not afraid to scrap several months of work and start over with the benefit of lessons learned.

I would like to do some cutter tests later this month and will post some video afterwards. Right now I am working on the burble compensation algorithms. There are many layers to the decision making software, and we are knocking them off one at a time.

We are learning as much as we can out of the Rev-A design, and have compiled quite a list of changes and improvements that we want to implement in the Rev-B design which I would like to have done by next spring. Once we are no longer identifying things that need to be addressed or could be better, we will be contacting those who have offered to help with the Beta testing.

I would like to thank everyone who has offered their support and encouragement.

[hackish 8]

I think your project is really cool, and it's been quite some time since I first saw you were working on it. While I don't love the shape, especially for those of us with smaller rigs, I believe the final production version should give you the ability to shrink your design. Battery technology and processors continue to shrink in size. I look forward to seeing this product make it to market.

-Michael

[df8m1 19]

hackish

I think your project is really cool, and it's been quite some time since I first saw you were working on it. While I don't love the shape, especially for those of us with smaller rigs, I believe the final production version should give you the ability to shrink your design. Battery technology and processors continue to shrink in size. I look forward to seeing this product make it to market.

-Michael

There have been a couple different case design concepts based on battery capacity / type. Here are two pics for a comparison of the current case to a Cypres 1. This case fit nicely into a standard AAD pouch.

It is the batteries that dominate the physical design constraints, and my goal was to get two years / 500 jumps out of a set of batteries based on power usage estimations. It has three ER18505M cells in parallel. Only real life usage will tell how well the batteries do and how well we handle power management. When this thing is at full power, it is doing a lot of work and is going to use more power than any AAD currently available, and there is no way to get around it.

You are correct that the natural evolution of hardware and design will promote more efficient designs. During the testing of the Rev-A design, we have identified several changes that we want to implement in the Rev-B design. All are related to peripheral aspects and not the business side of the AAD, which is what we are testing now.

I am very excited about how this is coming together. I really want to get some jumps on the one we have packed up! The decision to self-fund has slowed the rate of progress, which is frustrating, but much less frustrating than development time being limited by deadlines set by venture capital schedules. I want to get this right and if it takes a little longer than I want, then so be it.

This thing can tell if you are on the ground, or in the plane, in the plane or have exited, are in free fall or are in a wing suit, if have deployed your main or not. It calculates the firing altitude based on your speed and when the reserve should be fully open by, which is 500ft AGL if there is no main deployment, and 300ft AGL if there was a main deployment. The firing altitude window is 1250 ft to 1000 ft at a speed of 35M/Sec and faster for free fall jumpers. For a wingsuit if you enter the window and no main deployment has been detected and you are still in wing suit flight mode, then it will fire. (Each condition by itself is detectable to a very high degree of confidence; together the confidence level is even higher)

Once a main deployment has been detected, the firing altitude is calculated based on a 300ft AGL fully open reserve altitude, which is what I call the Point Of No Return altitude, which is meant to delay firing the reserve as long as possible allowing either the main to open if dumped low, or the jumper to deal with a malfunction with a descent rate above 35M/Sec before firing the reserve into the mess. In reality, depending on the speed, the difference is only a few seconds, but that time could be the difference between a two out and or a double malfunction.

It can detect a cutaway and if the Reserve has deployed or not. If the jumper cuts away above the upper hard deck (1250 ft AGL), then the firing altitude is calculate based on a 500ft AGL fully open reserve altitude. If the reserve has deployed before the jumper reaches the calculated firing altitude, then no fire. If however, if the Reserve has not been deployed by the time the jumper reaches the firing altitude, it will fire. If the jumper cuts away with in the window of 1250ft AGL and 300ft AGL the PONR firing altitude will be calculated, (again based on the descent rate of the jumper), and if the reserve has not deployed by the time the jumper reaches the firing altitude, then it will fire. If they are really low, it may very well beat the jumper to it. Once bellow 300ft AGL, it will not fire regardless.

It can tell if you are flying a wingsuit or are under canopy, and if you are under canopy it will not fire regardless of speed or altitude. It is only after a cutaway and only above 300ft AGL that it will be able to fire once you are under a main canopy.

This AAD will allow you to confirm that it is calibrated to your elevation, just like you check to be sure your altimeter is zeroed before each jump. I think every AAD should display the barometric pressure that is referencing as ground level, and that every DZ should have a calibrated digital barometric pressure readout that the jumpers can compare their AAD calibration to. I think there is already one AAD on the market now that will let you see what pressure it is calibrated to but I am not sure. It is my opinion that an AAD, regardless of type, should be checked for operation and calibration before every jump.

This AAD has a Bluetooth module and we are working on an app that will allow the jumper or their rigger, if they choose to do so, to upload the results of the selftests so we can monitor for any potential problems, and alert the jumper before they become problems. Only the selftest results would be uploaded, none of the jump data would be accessed. This is what many of the auto manufactures are doing now as it allows the manufacture to monitor how the product is doing without inconveniencing the owner or waiting several years to find out there is a problem that has been present for a year.

Each of these capabilities requires a lot of testing to validate that the algorithms are working as intended. It is my goal to have the alpha testing done by this spring / early summer, however that schedule is fluid. Once we have at a certain level of confidence, we will be seeking funding to bring it home and to market.

We are focusing on the military version as the US Government is looking for Enhanced AADs, and they are look at ours. The military version will have some features that the sport one does not, and the sport one will have features that the military one does not, but the hardware will be the same.

This AAD is a departure from the traditional AAD, and I understand that some will not be comfortable with that, or even think it necessary. There is nothing wrong with that thinking, but they are not who my team is build this AAD for. I am very curious to see if any of the other AAD manufactures add any of our capabilities into their AADs in the future. We are at the beginning of the fun part of the process and I am looking forward to the day we are ready to release our creation to the world.

If anyone has any questions, please do not hesitate to ask. I will do my very best to answer them without sharing any trade secrets.

[mxk 1]

Idea for another feature: Add a microphone and have the AAD listen to the conversations in the loading area. If it hears a dive plan so stupid that it's bound to end up on Friday Freakout, deploy the reserves preemptively to prevent the participants from boarding the plane.

Thanks for sharing all those details. I think using canopy-fully-open-by altitude is a great target, but I wonder how realistic is it to achieve a deployment by 300 ft given the number of variables that you don't control, starting with what the pilot chute will do once it is out of the container, and whether there will be any other hesitations depending on the body position, fall rate, etc., with the Wings RPC-in-tow being an extreme example. It just seems like the margin of error in the entire deployment sequence can easily exceed 300 ft.

Likewise, I'm surprised that you chose to have it disarm below 300 ft. Vigil uses 150 ft as the disarm altitude, but your AAD has much better situational awareness. If it detects fast fall rate not associated with a swoop below 300 ft, why wouldn't you want it to fire just to get as much fabric out as possible?

df8m1

It can tell if you are flying a wingsuit or are under canopy, and if you are under canopy it will not fire regardless of speed or altitude.

So hypothetically, if you do an XRW jump where the canopy pilot and wingsuiter dock and then spiral down to 1,000 ft, the wingsuiter's reserve will fire, but the canopy pilot's will not?

df8m1

I think every AAD should display the barometric pressure that is referencing as ground level, and that every DZ should have a calibrated digital barometric pressure readout that the jumpers can compare their AAD calibration to. I think there is already one AAD on the market now that will let you see what pressure it is calibrated to but I am not sure.

Vigil reports the current pressure reading (QFE) and you are supposed to convert and compare it against the sea-level pressure (QNH) reported by the nearest AWOS station if a calibrated barometer isn't available (Vigil Rigger Manual, p27):

Quote

In addition, we recommend that each two year the pressure sensor is checked and compared with a calibrated barometer or calculated by determining the QNH of the location (barometric altitude of a given place at a given time). Should the reading show a difference of more than +/- 10 hPa from the QNH, please get in touch with AAD SA or with the closest Vigil ® Service Center.

Note that +/-10 hPa = 0.296 inHg = 296 ft. That's a pretty big margin of error, if you ask me, which is another reason why I wonder about your choice of 300 ft. I check mine at every reserve repack and the most recent error was 30 ft.

[df8m1 19]

mxk

Idea for another feature: Add a microphone and have the AAD listen to the conversations in the loading area. If it hears a dive plan so stupid that it's bound to end up on Friday Freakout, deploy the reserves preemptively to prevent the participants from boarding the plane.

Thanks for sharing all those details. I think using canopy-fully-open-by altitude is a great target, but I wonder how realistic is it to achieve a deployment by 300 ft given the number of variables that you don't control, starting with what the pilot chute will do once it is out of the container, and whether there will be any other hesitations depending on the body position, fall rate, etc., with the Wings RPC-in-tow being an extreme example. It just seems like the margin of error in the entire deployment sequence can easily exceed 300 ft.

Likewise, I'm surprised that you chose to have it disarm below 300 ft. Vigil uses 150 ft as the disarm altitude, but your AAD has much better situational awareness. If it detects fast fall rate not associated with a swoop below 300 ft, why wouldn't you want it to fire just to get as much fabric out as possible?

Good points! The upper target for a fully open reserve is 500ft AGL and the firing altitude is determined by the descent rate of the jumper and the TSO 3 second requirement. In reality, the reserve should be fully open above the target, which leaves some cushion for slower opening reserves and or problem with deployment as you mentioned.

Lets say that the RPC hesitated bad and delayed freebag extraction for X seconds, the air between 500ft AGL and the ground is still available for the reserve to open if needed.

In order for the 300ft fully open reserve altitude to be calculated, there must have been a main deployment. So there will have been something out, slowing them down some what.

In the case of a bag lock (high speed) it would calculate the altitude, while falling at the current speed, necessary to have a fully open reserve by 300ft AGL.

You bring up a good point about the 300ft disarm height. I can make it anything I want, and nothing is etched in stone at this point, so if an argument can me made that a lower disarming altitude would be better, then I am open to listening :).

Where the 300 ft comes from is that is the PONR reserve canopy fully open by target. As you also pointed out, there needs to be some "extra runway" if the reserve is slow or there is a problem.

This lower hard deck is for when the jumper is dealing with a malfunction, or to put it another way, things are not going to plan if the PONR firing altitude is calculated, and I am uneasy about reducing the cushion to be honest.

If the jumper has a malfunction with a descent rate below 35M/Sec, and rides it to the ground, then it will not fire. Right now I am waiting 3 seconds from when a cutaway is detected to when I declare a cutaway, so if in the case of the jumper riding a mal with a descent rate bellow 35M/Sec down, and then chopping at 300ft, then it will fire bellow 300ft but only 3 seconds worth of descent.

That is what is behind my current thinking, and I by no means think that it is perfect. It is critical that this kind of peer review takes place, because the more people thinking about all the different situations that are possible, and then challenging me with them, can only result in a better end product.

Everything I do, or don't do, is based on something other than "another manufacturer does it that way". I am sure they have their reasons as well. I am interested in discussing what the "best" disarming altitude should be.

I would be very interested to see how low a reserve deployment at bellow 35M/Sec can be before there is no chance of it getting out of the bag.

mxk

***It can tell if you are flying a wingsuit or are under canopy, and if you are under canopy it will not fire regardless of speed or altitude.

So hypothetically, if you do an XRW jump where the canopy pilot and wingsuiter dock and then spiral down to 1,000 ft, the wingsuiter's reserve will fire, but the canopy pilot's will not?

I am trying to picture what that configuration would look like.... Do you mean a wingsuiter is flying straight and level, then a canopy pilot comes in above him and settles down on top like a rodeo? Then the canopy pilot induces a turn and the wingsuit and canopy pilot spiral down to 1000ft?

If so, my first thought is that is not a good idea lol... Regardless, to answer your question. Yes.. sense the wingsuiter will still be in flight configuration (the fact that someone is docked on his back does not affect that), and a main deployment has not been detected, then when they hit 1000ft, it will fire.

My thoughts on this situation may seem cold, but anyone using an AAD needs to understand the conditions in which it will and will not fire.

mxk

***I think every AAD should display the barometric pressure that is referencing as ground level, and that every DZ should have a calibrated digital barometric pressure readout that the jumpers can compare their AAD calibration to. I think there is already one AAD on the market now that will let you see what pressure it is calibrated to but I am not sure.

Vigil reports the current pressure reading (QFE) and you are supposed to convert and compare it against the sea-level pressure (QNH) reported by the nearest AWOS station if a calibrated barometer isn't available (Vigil Rigger Manual, p27):

Quote

In addition, we recommend that each two year the pressure sensor is checked and compared with a calibrated barometer or calculated by determining the QNH of the location (barometric altitude of a given place at a given time). Should the reading show a difference of more than +/- 10 hPa from the QNH, please get in touch with AAD SA or with the closest Vigil ® Service Center.

Note that +/-10 hPa = 0.296 inHg = 296 ft. That's a pretty big margin of error, if you ask me, which is another reason why I wonder about your choice of 300 ft. I check mine at every reserve repack and the most recent error was 30 ft.

I thought it was Vigil... you have measure the pressure at the DZ. The pressure readings at different locations can vary that much, which is why they put that tolerance in there.

My programmer did the same thing.. He said that the baro sensors were way off, I said what are you basing that on. He said he was using weather service pressure data or something (that was a while ago lol). I compared the sensor readings to the calibrated pressure readout that I calibrate my altimeters to and it was with in .02 HG with out being calibrated. (the soldering process stresses the membrane, so to get it dead nuts after the boards are assembled, the senors have to be calibrated).

This AAD also has two barometric pressure transducers. One in the interface, and one in the ECM (black box). This allows us to compare the readings of the two and provides a back up if the primary one has a problem between exit and the ground.

My point to checking the Ground Level Reference Pressure, as I call it, is to know that the AAD is adjusting for weather changes, just like we have to zero our altimeters throughout the day.

In addition to displaying the Ground Level Reference Pressure that is stored and the AAD uses to identify there the ground is, it also tells you how long it has been sense it was last checked. (how old the reading is).

So during the prejump gear check you push the button, and the AAD wakes up, and displays the stored pressure reading in Hg, a format that is easy compared to digital barometer, and it also tells you how old the reading is.

If the reading is older than it should be, then the AAD is not updating the Reference Pressure, which could result in impacting at line stretch after an AAD fire. Or, if the pressure reading is too far off, then there is a problem, causing the potential for impacting at reserve line stretch. (if the main pressure sensor differed too much from the secondary, then it would through a fault code.)

There is a tendency to try and cover every conceivable instance when there is the "potential" to do so, and that often is in conflict with keeping if from being overly complex. We are going to continue to rely on traditional training and protocols like do not turn it on at home and then drive the the DZ... Do not turn in on in the plane (this is for the sport AAD, the military one can be turned on in at altitude).

If two people want to operate outside the range of "excepted best practices" then the idea that there may be some conflicts that will not end well should not be a surprise lol..

Every DZ I have been to requires wingsuiters to be in the saddle by 2K.. But I am sure any discussion about the merits of going lower will be entertaining :)

[mxk 1]

df8m1

You bring up a good point about the 300ft disarm height. I can make it anything I want, and nothing is etched in stone at this point, so if an argument can me made that a lower disarming altitude would be better, then I am open to listening :).

Why have a disarm height at all? I mean firing at 10 ft is going to be pointless no matter what, but if your AAD can actually distinguish a swoop under a good canopy vs. a malfunction, why wouldn't you want it to fire if it detects imminent impact at a non-survivable speed? Basically, why have that extra branch of code in there if the rest of the logic is good enough to not do the wrong thing?

df8m1

******It can tell if you are flying a wingsuit or are under canopy, and if you are under canopy it will not fire regardless of speed or altitude.

So hypothetically, if you do an XRW jump where the canopy pilot and wingsuiter dock and then spiral down to 1,000 ft, the wingsuiter's reserve will fire, but the canopy pilot's will not?

I am trying to picture what that configuration would look like.... Do you mean a wingsuiter is flying straight and level, then a canopy pilot comes in above him and settles down on top like a rodeo? Then the canopy pilot induces a turn and the wingsuit and canopy pilot spiral down to 1000ft?

If so, my first thought is that is not a good idea lol... Regardless, to answer your question. Yes.. sense the wingsuiter will still be in flight configuration (the fact that someone is docked on his back does not affect that), and a main deployment has not been detected, then when they hit 1000ft, it will fire.

My thoughts on this situation may seem cold, but anyone using an AAD needs to understand the conditions in which it will and will not fire.

Correct: https://youtu.be/0bdA3Ej0WQc?t=71 and https://vimeo.com/230213719

The wingsuiter could be on his back as well, docked by the chest strap. In this (very unlikely) scenario, the velocity and acceleration vectors are not going to look like normal wingsuit flight, so I was just curious if this would confuse the AAD and what it would do in that case.

df8m1

So during the prejump gear check you push the button, and the AAD wakes up, and displays the stored pressure reading in Hg, a format that is easy compared to digital barometer, and it also tells you how old the reading is.

If the reading is older than it should be, then the AAD is not updating the Reference Pressure, which could result in impacting at line stretch after an AAD fire. Or, if the pressure reading is too far off, then there is a problem, causing the potential for impacting at reserve line stretch. (if the main pressure sensor differed too much from the secondary, then it would through a fault code.)

Yea... I'm thinking that there is exactly 0% chance of getting your average skydiver to do this even for just the first jump of the day. Most people don't even look at the AAD before each jump if it's hidden under a flap.

If you really want to alert them to any kind of malfunction after the start-up sequence, I think emitting a sound is about the best you'll be able to do. The next step would be to send an alert via Bluetooth to their phone once your app is ready (and then you may as well have your app pull the METAR data from the nearest airport based on the user's location and compare the pressure readings automatically)

[mrubin 0]

Quote

My point to checking the Ground Level Reference Pressure, as I call it, is to know that the AAD is adjusting for weather changes, just like we have to zero our altimeters throughout the day.

In addition to displaying the Ground Level Reference Pressure that is stored and the AAD uses to identify there the ground is, it also tells you how long it has been sense it was last checked. (how old the reading is).

So during the prejump gear check you push the button, and the AAD wakes up, and displays the stored pressure reading in Hg, a format that is easy compared to digital barometer, and it also tells you how old the reading is.

I think that most skydivers would find it easier to check if it displayed the altitude and not just the pressure. We are used to checking that our altimeters are zeroed and, in my opinion, it would be easier to check for the same thing on our AAD.

"I fly because it releases my mind from the tyranny of petty things." - Antoine de Saint-Exupery

[pchapman 261]

mrubin

We are used to checking that our altimeters are zeroed and, in my opinion, it would be easier to check for the same thing on our AAD.

A zero altitude on an AAD isn't a way to tell whether the pressure sensor is reading accurately. (It could catch some errors, but not others. It could have pressure sensor problems but chose to consider that wrong value to be ground level.)

But it does have some usefulness. At least helps understand what mode the AAD is in. "Does it think I'm still airborne? What about that car ride to the DZ? Has it updated recently for weather changes?" That's a issue for AADs.

[df8m1 19]

mxk

Why have a disarm height at all? I mean firing at 10 ft is going to be pointless no matter what, but if your AAD can actually distinguish a swoop under a good canopy vs. a malfunction, why wouldn't you want it to fire if it detects imminent impact at a non-survivable speed? Basically, why have that extra branch of code in there if the rest of the logic is good enough to not do the wrong thing?

You bring up a good point, and that thought has gone thorugh my head, but it kept going lol...

I don't want to get in to detail about how I have the logic organized and working, but the "disarming" point is not an separate subset of commands, so there would not be any saving s of any significance. Having thought about it as I was doing other things today I realized I may have some form of OCD lol..

For some reason, and I don't know why, but i feel the need to shut down functions when they are no longer useful. Now you have me analyzing myself! lol

I am pretty sure you are not advocating bringing the lower full open reserve canopy altitude down from 300ft, but rather, allowing it to fire if a jumper cuts away between 300ft and the ground?

That is where my OCD is kicking in lol... I am fine with allowing it to fire in the event of a cutaway bellow 300ft, there is a voice in my head that wants to disarm it at 100ft at least, and I will try to enplane why..

The algorithms are designed around canopy flight and events that can happen between the plane and the ground... Where I get uncomfortable is the touchdown aspect of the flight. I keep seeing a picture in my head of a pilot punching it out and popping way up, practically stalling, and then then taking the down elevator to the ground.. And it is not that I am "significantly" concerned about the conditions mimicking a cutaway or in some way fooling the algorithms, but that is why some hot canopy pilots are going to put it through its paces :).. To your point of not having extra code addressing unnecessary aspects, I think having to add pre-touchdown and touchdown conditions to the matrix would do just that. I will meet you 2/3 of the way and set the disarming at 100ft :). That just makes it simpler to not have to test for conditions where the reserve is worthless anyway.

Does that make any sense? lol

mxk

***So during the prejump gear check you push the button, and the AAD wakes up, and displays the stored pressure reading in Hg, a format that is easy compared to digital barometer, and it also tells you how old the reading is.

If the reading is older than it should be, then the AAD is not updating the Reference Pressure, which could result in impacting at line stretch after an AAD fire. Or, if the pressure reading is too far off, then there is a problem, causing the potential for impacting at reserve line stretch. (if the main pressure sensor differed too much from the secondary, then it would through a fault code.)

Yea... I'm thinking that there is exactly 0% chance of getting your average skydiver to do this even for just the first jump of the day. Most people don't even look at the AAD before each jump if it's hidden under a flap.

If you really want to alert them to any kind of malfunction after the start-up sequence, I think emitting a sound is about the best you'll be able to do. The next step would be to send an alert via Bluetooth to their phone once your app is ready (and then you may as well have your app pull the METAR data from the nearest airport based on the user's location and compare the pressure readings automatically)
In reality that is more from me and how I always wanted my AAD to work. I design things to be how I would want them.

If there was a problem, like the calibration did not update, or the pressure sensors difference beyond limits, it would set a code and shut down. If the jumper buys into the "set it and forget it" mentality, and does not check the AAD and reserve pin before they jump, then it is on them if they hammer in.

Jumpers these days put way to much faith into AADs IMO. 6 of my 7 aff levels were done with rigs that had a little metal box at the hip junction and I was told to be prepared for a reserve fire when I did not expect it to... After I graduated and had a few jumps on rental gear, the awesome DZO loaned me an old container and reserve to jump, as I had a new saber 170 in my hands. My JM told me that it was a "Darwin Rig", just like he jumped... It only had three handles and it was on me to get it done in time.. I put a bunch of jumps on that rig before I got my brand new container with an RSL! lol...

To me when someone tells me that they, have never, and will never jump without an AAD, I have to remind myself that this is a different time then when I "grew up"... And it is those same people, who put so much faith in their AAD that probably have never read the user manual, and will think it is ok to cutaway bellow 300ft because the AAD will save them lol...

Sorry for the rant.. It is been a ruff day :(

[df8m1 19]

pchapman

*** We are used to checking that our altimeters are zeroed and, in my opinion, it would be easier to check for the same thing on our AAD.

A zero altitude on an AAD isn't a way to tell whether the pressure sensor is reading accurately. (It could catch some errors, but not others. It could have pressure sensor problems but chose to consider that wrong value to be ground level.)

But it does have some usefulness. At least helps understand what mode the AAD is in. "Does it think I'm still airborne? What about that car ride to the DZ? Has it updated recently for weather changes?" That's a issue for AADs.

Mrubin.. Although the idea of displaying the altitude does make sense, the problem is it never reads 0... The only place where it could possibly read 0 is at sea level when the pressure and temperature match the standard level for each.. So then the next logical thought is, "well then display the DZ altitude".. but there is a problem with that too..

The AAD reads "Pressure Altitude" just like an altimeter does, and as the barometric pressure changes during the day, so does the "perceived" DZ altitude. That is why aircraft altimeters have an adjustment for pressure, which they are always adjusting based on what the current pressure is.

So the easiest reference value is barometric pressure in Hg, which any digital barometer will display.

In reality, an AAD does not care what the actual DZ altitude is, but rather what the pressure is at that location, and it uses a formula to calculate the altitude based on the change in pressure from the pressure at that location.

When you off set the landing altitude, you are not actually changing an altitude value... what it does is convert the 200ft offset you entered, into the difference in pressure at 200ft from the take off pressure..

Pchapman,

After the this AAD has been turned on and the modes set and yada yada... when the jumper pushes the button during the prejump gear check, it will first display the Ground Level Refference Pressure and when it was taken, then it will display the aircraft mode that it is set to, (I have not gotten into that yet), then it will display the jump mode it is in.

After take off, if the button is pushed it will say "Aircraft Mode" (which one it is in), and display the current AGL altitude, then it will display the which jump mode it is in. Then it will go dark. The only option while in flight is to turn it off, after take off, you will not be able to change the aircraft or jump flight modes.

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