Deployable Elts... Doable?

[SJESOFFICER]

Note to readers this was talken from Searh for Fossett and moved to its own topic...

As for elts I would say the least they could do is reeinforce them with a steel box so it'll take a little more of a beating then hard plastic would... but then you get into weight factors.  Hmm maybe like the Siris has an emergency parachute system maybe elts should be deployed by a tail wire to keep it a little ways away from the plane if an emergency occurs...might even be easier to deactivate on those udf missions...if I were to try to adapt the standard elt to be deployable I don't think much weight would be added, 30 ft of tether, 3/4 steel line bolted to the tail.  as to to install it on all the a/c I wouldn't go that far just because  siris made a plane with a chute on, doesnt mean  older planes  have to adopt it.  I guess overall I think someone can make a tethered deployable elt priced for private use. as for weight you just have to account for the tethered line and detachment mechanism into the slipstream. Possible have an aquator release it through a switch like the one they use already to manually activate the elt. I think I will transfer this to its own topic, and maybe we have some engineers who can comment. it may not be realistic but then ideas don't become realities until their actually made...  Ask yourself this if one was made affordable and was more reliable than the current equipment wouldn't you want one...

[lordmonar]

the last thing I want in an emergency is a 1 lb box dangeling 30ft behind my airplane.

The ELTs are pretty rugged.  The weak point is the antennas.

[SJESOFFICER]

An ELT that deploys in the event of an accident exists.  It is a follow-on to combination ELT/cockpit voice recorder/flight data recorders that have been around for years.  These are called Deployable Flight Information Recorder Systems (DFIRS).  They are primarily used on military aircraft, but are available and used on civilian aircraft, both fixed wing and helicopters.  The FAA has has approved them and the NTSB would like to see them used more.  From DRS Technologies, the prominent manufacturer in the field.

The electronics are packaged within a crash survivable Beacon Airfoil Unit (BAU) that is qualified and certified to CAA, TCA and FAA standards. In the event of an accident, the deployment of the BAU is automatically triggered by on-board sensors, thereby allowing the BAU to escape the devastating effects of the crash. The ELT immediately transmits its distress signal, including aircraft identification number, to the COSPAS-SARSAT network. With its Global Positioning System (GPS) encoding option, the BAU transmits the aircraft's last known latitude and longitude to aid in search and rescue efforts. The BAU floats indefinitely, providing superior survivability and localization of crew and aircraft that crash in water.

For military models: In the event of an accident, the deployment of the DFIRS is triggered automatically by an impact sensor or through release of the ejection seat. Activation by either of these means initiates the deployment mechanism that releases the DFIRS into the aircraft slipstream where it "flies" away from the aircraft.

Obviously a DFIRS is not something that one is going to install on a general aviation aircraft, and I suspect the cost of a deployable 406 ELT is astronomical, but the idea of a deployable beacon is in real world use.

More info:
CPI-406 Deployable ELT

Mike

I think a elt dangling from your a/c isn't gonna matter it shouldn't affect ur flight characteristics too much and if your going to crash nothing you can do about it... fyi I am not a pilot so i am ok with being wrong... tell me for what reasons specifically you wouldn't want it back there... Personally if i knew i was crashing I wouldn't want it crashing with me give it  30 ft and maybe it'll survive a fire and initial impact better...

[SDF_Specialist]

Well what about internal antennas? What are the pros and cons regarding them?

Pro: They are safer from impact than exposed

Con: They would produce a lesser signal

That' actually about all I can think of. Can anyone else think of any?

[jeders]

Well what about internal antennas? What are the pros and cons regarding them?

Pro: They are safer from impact than exposed

Con: They would produce a lesser signal

That' actually about all I can think of. Can anyone else think of any?

Con: When the aircraft is reduced to two pieces of sheet metal separated by a couple of inches of gap, the internal antenna will also be reduced in size.

And based on Gauss' Law and Ampere's Law, if the electromagnetic signal was confined within a Gaussian surface, no signal will go through. Now of course an airplane is hardly a Gaussian surface, there are windows and openings for the signal to go out through, but still Internal isn't that great.

[♠SARKID♠]

Well what about internal antennas? What are the pros and cons regarding them?

Pro: They are safer from impact than exposed

Con: They would produce a lesser signal

That' actually about all I can think of. Can anyone else think of any?

One word: Tampering.  CAP isnt always the first on the scene and the last thing we need are people messing with/shutting off the ELT and mucking us up.  Happened last month on a plane crash here in WI.  Team went out and the fire dept shut the ELT off before they got there because the airport manager advised them to (no jurisdiction there).  They didnt take down the correct info any info as for times or anything like that (Matt, more details?).  Having the ELT dangling out in the open is a bad idea, theres enough problems when its tucked away in the empenage.

[SDF_Specialist]

What I meant by internal antenna was something built inside the unit itself, not inside the a/c. Of course, there is always the possibility of giving more power to the beacon, giving it a greater output.

[♠SARKID♠]

Oops, mis-post, please delete moderaters.

[SJESOFFICER]

As for the deployable elt... it would be internal until deployment... and as far as tampering i would rather have it findable to be tampered with then not found in time or never found at all.  I am assuming if the fire dept deactivated it , they were near the crashed plane and able to render any medical needs if that were the case...

[SarDragon]

Same post as the Fossett thread, with additions.

[redacted] if I were to try to adapt the standard elt to be deployable I don't think much weight would be added, 30 ft of tether, 3/4 steel line bolted to the tail.  [further redacted]

Ten meters (33 ft)  of 19 mm (3/4 in) steel wire rope weighs 27 lb, and has a working wieght limit of 7052 lb. I think that's way overkill.

OTOH, 10 m of 3 mm (1/8 in) steel wire rope weighs about 1 lb, and has a working weight limit of 175 lb.

But you still need all the rest of the hardware in the airframe to make it work.

And nobody answered the $64 question - Who's going to pay for it?

Continuing:

As for an antenna internal to an ELT, you might as well not bother having the unit. The antenna needs to be at least 1/4 wavelength in order to have any decent efficiency. That's one of the reasons the antennas are externally mounted on the A/C. The foldaway antennas mounted on some ELTs work well enough to be detected in dumpsters, but still run the risk of damage during deployment or on landing.

Regarding the Deployable Flight Information Recorder Systems (DFIRS), I worked with the version mounted on the Navy P-3s. It was as big as a Cessna 172 door window, and probably weighed 20 lb installed. Can't find any stats on it, but I'm sure the cost was in the tens of thousands of dollars. The F/A-18 would seem to be smaller, but probably more expensive.

You mentioned the word option. That means that many owners will opt not to install this new expensive item. Many owners already exercise that option regarding the new style ELTs. What makes you think the money wil flow any more freely for this newer, even more expensive option? Think back on safety equipment installed in cars. All the really useful stuff had to be mandated before there was any large scale effectiveness. New ELTs are no different.

[SJESOFFICER]

Yea I agree 3/4 would be overkill, its just something I threw out there... I was thinking just using a regular old elt with a flexable antenna on one end (so it wont bend and break) and the tether on the other end.  The whole idea is get the elt out of the crashing or distressed plane so in the event of a crash or fire it has a chance of survival. As to the price I could see it being very cumbersome but I think it can be engineered in a simple matter to where it would only cost at most 50 not including the elt. It could be an option... but hey if it increases survivability then maybe it'll become mandatory and only a little more than what you usually pay.  And by no means am I a pilot or engineer so I cant really say if its doable and the price relates on simplicity. If its a really simple system that works then you have you answer, if not then we stick with what we have. Just have an inventive side to me

[Al Sayre]

It seems to me that an ELT on a tether in a crash would be like having a brick on a tether in a crash.  If the angle of impact is any more than about 5 degrees, you're going to have that 2 lb object impacting the stationary (already crashed) aircraft at 100mph plus, 1/4 of a second after the crash.  It would be better to have it drop loose in say a 5 mile vicinity of the aircraft.  Close enough to alert the searchers, but far enough away to limit possible additional damage.  But then there is the liability issue when it comes through the roof of some little old ladies house...

[SDF_Specialist]

OK, maybe the internal antenna was a bad idea. So how about multiple antennas? One for each side of the plane, reinforced in an attempt to minimize damage done to the antenna to try to increase the odds of a signal, assuming the ELT survives the crash.

[SJESOFFICER]

Hmm if you want a something to slow down in the air... add an air sock but not one big enough to cause any change in plane control.

[Dustoff]

If I'm flying the airplane that is in a precarious position, I'm sure I have BOTH HANDS AND BOTH FEET busy trying to FLY that airplane (and maybe avoid that crash all together!!)

I'm not gonna have time to deploy nuttin.....

The number one thing a pilot ALWAYS HAS TO DO is FLY the D#&*N AIRPLANE.

And that's all the way until it's parked safely on the ramp.

Jim

[SJESOFFICER]

hmm ... automatic deployement once you pee in your pants or have a bowl movement... jk jk of course...
*Written on Mobile PDA Sorry for All and Any Mistakes of Spelling/Punctuation etc.*

[SDF_Specialist]

If the topic of automated deployment is about, how about this; the ELT deploys during rapid loss of altitude.

[SJESOFFICER]

Makes it a little more complicated and weighty but it could work that way...

[♠SARKID♠]

If the topic of automated deployment is about, how about this; the ELT deploys during rapid loss of altitude.

Good luck when you practice stalls.  Wouldnt work.  If you do a stall, or hit an air pocket, the ELT would deploy even though its not an emergency.  Not to mention if you have to do a rapid drop to get  below closing cloud cover.  Then you would have a box on a tether dangling off your plane until you can make it back to an airport. Then it would be dragged across the ground on landing, leaving parts and FOD strewn about the runway where other aircraft can suck it into their engines, or hit it as they land/takeoff.

[SDF_Specialist]

If the topic of automated deployment is about, how about this; the ELT deploys during rapid loss of altitude.

Good luck when you practice stalls.  Wouldnt work.  If you do a stall, or hit an air pocket, the ELT would deploy even though its not an emergency.  Not to mention if you have to do a rapid drop to get  below closing cloud cover.  Then you would have a box on a tether dangling off your plane until you can make it back to an airport. Then it would be dragged across the ground on landing, leaving parts and FOD strewn about the runway where other aircraft can suck it into their engines, or hit it as they land/takeoff.

Good point. Hmm. There really doesn't seem to be any logical idea other than the one that's implace. I still like my idea of multiple antennas though.