Mfcttrf

The subject pretty much states my question, now I will provide a bit of background.

A family member, who lived on the west coast of Florida Manasota Key, collected tens of thousands of fossilized sharks teeth between the mid-1940s and the late 1970s. I have now become involved in deciding what to do with these sharks teeth. Here is one of the multitude of pictures available showing samples of these types of sharks teeth:

The vast majority of this collection ranges in size between a dime and a quarter and likely has the same level of hardness.

If you've visited one of the beaches in this part of Florida in the last 25+ years, you probably know that finding these treasures is no longer as easy as it used to be. When I was a kid (late 1970s), I could usually come up with 10+ teeth in about a 2 hours stretch. However, by the time my kids were of the age where this would be of interest (early 2000s), we were lucky if we found one a day.

What I'd like to do is return these teeth to the area just off shore of this beach thus giving future searchers a better chance of "re-finding" them.

Lets assume for the purposes of this question that the airplane involved would be a Cessna 172s. My question is, what would be a good way of doing such a drop without harming the aircraft itself? I assume just dropping them out the window risks blow back that could damage the aluminum fuselage or tail assembly.

A couple of notes:

• This is NOT a question about the legality of dropping items from an airplane in the United States. I am well versed with 14 CFR § 91.15 - Dropping objects, which states:

No pilot in command of a civil aircraft may allow any object to be dropped from that aircraft in flight that creates a hazard to persons or property. However, this section does not prohibit the dropping of any object if reasonable precautions are taken to avoid injury or damage to persons or property.

• Not interested in a solution harmful to the environment. Thus dropping them in taped boxes or rolled up newspaper would not be warranted because that would be littering.




• I'm certainly aware that renting a boat and dropping them off the side would be an alternative. That said, for the purposes of this question, I am specifically asking how to achieve this using a Cessna 172 (or similar) high wing GA airplane.

Spitballing an idea... Not sure of the legality or practicality of this, but it's an idea that came to mind.

Using a piece of 2-3" diameter PVC pipe (sized as necessary to clear the largest tooth), attach (very securely - using the appropriate PVC glue and, possibly adding some screws) it to one edge of a sturdy (heavy plastic) box. Add some eye bolts to the sides of the box.

When you reach the drop zone, attach ropes (with swivel connectors, like on a dog's leash) to the eye bolts, slide the pipe out the window/door so that it hangs into the air stream, but below the empennage, slowly pour the teeth into the other end of the box and let them slide down to the spout and out of the plane.

The pipe will guide them down far enough to clear the bottom of the plane and give you controlled output. The ropes (attached to something inside the plane prior to take off) will ensure the box doesn't go sailing out of the plane.

Out the window should work fine, assuming they're as dense as a typical fossil. The "blowback" hazard is with low-density or fine particulate materials such as the human ashes that you hear all the horror stories about.

You can fly at a lower airspeed to further improve the clearance from the empennage.

Rig a curved PVC tube running from window to behind and below tail and have passenger pour teeth through a big funnel. You may need a fairly large diameter pipe because with this version of pipe idea, the slope of the pipe is small, making it easier for teeth to jam. Maybe the end of the pipe will even drag on ground during taxi and takeoff run or at least when you rotate for takeoff, which should be ok as long as the pipe has some flex, as the pipe doesn't have to survive multiple uses. Check what pipe does when you put the aircraft tail tiedown ring on the ground before actually flying with this idea. Also check what happens when you turn while taxiing. Operating from a grass strip would help.

Calculate CG carefully!

Maybe even bring a pressurizable (pump-up) container of water to blast teeth out if get stuck, or something like a toilet snake, or just do sufficient tests on ground ensure won't get stuck. You may want to drop teeth in steep climb to make pipe steeper.

Obtain long collapsible plastic sleeve (I think you can buy this material on a roll somewhere?), cut piece long enough to clear tail, roll up, have passenger deploy out window or door and start shoveling teeth into sleeve with scoop. Even if bag initially deploys above tail, weight of teeth inside sleeve should eventually pull it below? The cockpit end of sleeve may need to be secured around a hoop or something to hold it open and give passenger a good way to hold on to sleeve. Will weight of teeth make them find way to end of sleeve despite any tendency for sleeve to twist up in airflow? That's the intention....

If they were marbles of the same weight, I think you could be sure would not hit tail if just poured out window, but maybe not with those teeth. Here's one solution: remove brace from side window to permit full opening. Put teeth in bag. (Optional: fill extra space in bag with sand to make heavier). Have top of bag tied shut with flaps that will open when a string pulls out a pin. Have bottom of bag securely tied to strong long rope. Throw bag out window, string comes tight first, opens top of bag, then rope comes tight and holds bag securely upside down. Or just do it with one rope, you just have a loose "bight" threaded through the rubber band that holds the bag closed, as is done with parachute shroud lines. (You could even buy a hang glider parachute deployment bag.)

Anyway after deployment the empty bag trails harmlessly way behind the tail till landing.

Better yet remove door and push bag out door. How big a bag would it take to contain all the teeth anyway?

Simpler- a strong-ish plastic bag like a trash compactor bag or heavy garbage bag. Remove door and passenger seat to accomodate huge bag with thousands of teeth. Bag is filled with teeth, bunched up on top, wrapped round with twine, then a long heavy rope is tightly tied around "bunched" point. Leave lots of excess bag material on top above "bunch" point so bag cannot slip out through twine and rope. Bag is tied to secure strong fuselage member or landing gear. To drop, do an extreme slip, or push bag out with broom or similar. Bag falls to end of rope, bottom rips open, teeth fall, empty bag trails well behind tail. (You'll use a rather long rope.)

Do tests on ground out of second-story window with same kind of bag to make sure it will consistently rip open when reaches end of rope and doesn't pull loose through rope and twine. Maybe using a bag full of same weight of gravel or sand, so you don't have to pick up all the teeth again. Of course the teeth will do a better job of ripping the bag than gravel or sand will. Make sure the bag is strong enough that the teeth won't rip the bag in the plane, and be sure the plane has an interior such that loose objects can't migrate to tailcone. Tie bag securely into place before takeoff with rope or strap that you can easily undo. Maybe better to leave passenger seat in place after all to facilitate buckling bag into place; also it will put bag in better postion for you to shove it out the missing door with one hand and avoid issue with bag clearing door sill. Make sure the bag cannot interfere with controls in any way!

A bag with a ripstop kind of "weave" (texture) would help stop minor tears and punctures from propagating before the drop, if such a thing exists in a disposable bag. You may end needing to double-bag the teeth- do some experimenting.

Secure open-top cask or barrel, or other similar container atop wing center section. Partially fill with teeth, leaving ample room between top of toothpile and top of container. Operate from beachside airport with only unpopulated beach and water along route of flight in case some teeth escape. Over drop zone, pitch up and then do -1G pushover to eject teeth and safely clear the cloud of teeth. Be sure to bring a G-meter of some sort such as may be purchased on-line in a solid-state electronic format or may even be available as a smart phone app.