neato

Wonderful technique, simple, yet effective. Innovation at its best. Please continue to polish the mechanics as I will follow this thread and use your same procedure in my 1/6 scale TBF Avenger. Chic

Hi Redtail: My next step is just to see how this apparatus works in flight. I think it will be just fine. I believe that the Avenger, also built by the "Grumman Iron Works" also has a similar tailhook arrangement as the F6F Hellcat and maybe other planes too.

What we need, especially for the larger planes, is a reliable gearing device that can convert the rotary motion of a servo to a linear motion of a device attached to the tailhook. I was looking into a gear that looks sort of like a comb that would ride back and forth in some sort of frame. I'd have to work some more on that idea, but if anyone has other ideas, this is a great place to share with us as there might be a number of modelers who would like to do something like this on their planes. It is definitely doable.

davegee

Hey DaveGee, my only thought or concern is whether the airflow from the model in flight will cause the carrier hook once extended, to almost move from a hook down position to a straight back position when extended out from the fuse. What do you think? Chic

"I love it when a plan comes together."

Right, Chad. I think the idea of a simple servo and long arm on a larger model would probably be problematic. I'd like to see a gearing system that would be a lot more efficient in a straight-line motion pushing the tailhook out. This idea works for the small foamie, but I would work something very different for larger plane.

Hi Redtail: you bring up a very good point. I can't really address that concern until I actually fly it and see what it does. I might do that tomorrow, possibly have someone else fly it while I have a good camera and take some pics as it flies by.

My thoughts are a couple of things: First, this working tail hook is only designed to be used for scale shows, or visual fly bys with the flaps and gear down as it does a low, slow dirty pass down the flightline or runway. So, it will be going at minimum speed which might help a little. Second, there is not a lot of drag on the aluminum tube and scale hook I carved out of basswood. The wood gives it just a tiny bit of weight and drag, but I"m hoping that it won't be enough to make the hook fly behind the plane like a streamer! We'll just have to see. If I can take some pics, I'll post them to show what it did indeed do. On a larger model, a small weight could be used in the hook that might make it hang down without bothering the overall CG.

That brings up an interesting question about the full sized Hellcat tailhooks. I am guessing that it was hinged just as mine is that makes it hang straight down outside of the fuse. I don't know if there were any springs or anything to make it stay that way, or if just the weight of it was sufficient. I've held some tailhooks and they are pretty stout, solid steel, or cast steel tips that weigh a substantial amount, I'm guessing at least 40-50 pounds. It was enough weight that land based planes like the Corsairs removed them whenever they weren't needed. If anyone knows more about the Grumman tailhooks used on the "cats" and the Avenger, too, I'd be interested to learn more about that.

Davegee

The weight at low speed would allow it to fall just fine me thinks,, so it must be heavy enough to accomplish that

I'm tempted to put the plane in our convertible and have my wife drive down the street with me holding the plane above my head to test out what happens to the tailhook, but I'd probably be taken to the loonie bin if I did that! If I do, I probably better go somewhere where my neighbors can't see me!
Still....

davegee

Or just fly it

It's like waiting to see what is wrapped under the Christmas tree, I HAVE to see how the tailhook responds, but I can't make it out to the field until at least tomorrow to actually fly it.

dg

There is a spring on the full size.

Thanks for that info, Chad. Do you happen to have any pics of a Hellcat tailhook in the deployed position?

davegee

OK, gang, just took the plane down the street in the convertible. Max speed 35mph, the hook does wobble a little in the wind, probably not perceptible in the air from the ground observer. It does come a little from the perpendicular as much as 20 degrees, but at least in this test, it still looked believable.

Will try the "acid test", flying it tomorrow or Tuesday. If possible I'll take some pics of it from the ground to evaluate how it looks in the air.

davegee

DaveGee, google the following: Grumman hellcat tail hook On page 1 of the search results, scroll down to F6F Hellcat At War, Page 37 Found a great drawing of the tail hook assembly. Chic

Thanks, Chic. That is a good drawing. I would really like to see a real one at a museum which would be very helpful. I was at the Naval Aviation museum last fall, but I was concerned about Corsairs, and didn't really look at the Hellcat. Have to make another trip sometime!

davegee

Nice job on the tail hook. Since you used alum tube why not fill it with lead? Lead shot or even steel bb's should add the weight you need and not effect the cg much.

That's a good idea! The tube is only about 1/8" diameter, but I could get something in there that might dampen out the wind buffeting without adding too much weight.

davegee

Hi All: took the Hellcat up today, checked out the new flaps and tailhook action. The flaps worked great, probably look better than they are functional, and the tailhook didn't blow off, and deployed and retracted just fine. The only issue is, as feared, that the airstream blows the tailhook almost straight back, even at approach speeds. So, there is some work to do there. What I am going to do in the interim is tie a piece of fishing wire to the tailhook that will keep it in place when it is deployed. That will at least make it look the way it should when it passes by the flightline in the dirty configuration.
I'll post a few pics, nothing really all that good, but I'll try again when I get the tailhook position figured out for flight.

davegee

You could make yourself up a little torsion spring like this,,

Thanks, Scale, that might be my next experiment. So far today I have tried using a spring that goes over the robart hinge on the tube (gets hung up coming in and out of the fuse), an elastic string, fishing line, and now a small magnet that is on the fuse, and a screw inside the aluminum tube of the tailhook to attract the magnet as the tube comes up and out of the fuse. But if the magnet idea doesn't work, I'll try fashioning a torsion spring as you suggest. Appreciate the input.

I was pleased that the tailhook came in and out of the fuse flawlessly on a number of tests. It just has to hang down without blowing back into the slipstream. I don't want to add weight to the tailhook, and I think if I did it by adding weight, it would have to be a LOT of weight to keep it down, but I'm just guessing at this point.

davegee

OK, I think I found a solution. I had some 1/2" diameter magnets lying around, so I glued one to the plate just below the opening for the tailhook. I glued a small bolt inside the aluminum tube of tailhook in the area where the magnet is, and as the tailhook comes out of its storage tube, it snaps onto the magnet below it and stays in position. I think it will resist blowing off of the magnet even with the airloads on it as it is flying. It is no problem at all for the tailhook to overcome the magnet's hold on it and retract normally into the fuse. I think this is now a workable system. I'll fly it in a couple days when I can get out to the field and see how it does.

Cheers

davegee

Absolutely brilliant idea. Will certainly put that idea to work with the Avenger if you say it works well for you and the servo has no problem pulling the hook up and away back into the tunnel. Chic

Hi Chic: the servo idea will work if you have LOTS of room in your Avenger, or if you come up with some other arrangement to move the tailhook in and out of the fuse. But the mechanism, at least how it looks in a model, is the same for the Wildcat, Hellcat, Avenger, and possibly some more that I can't think of right now. This is a workable system, and you should be good to go with making one for your Avenger. Let us know how it goes!

I'll take more pics of flight tests when I can with the magnet arrangement on the Hellcat. I feel pretty good about this working now.

davegee

Hi Chic: I don't know all that much about the Avenger, but it appears from some photos I pulled up on the internet that some planes have the tailhook come out the back of the fuse like the Hellcat and Wildcat, yet others have the tailhook mounted externally aft of the tailwheel where it would be levered down versus run out like the other planes.

I'm sure you are researching this, especially if it is going to be a detailed model of a specific plane. Just thought I'd bring up that tidbit to be sure you were aware of that, if it is important. Might have something to do with some that were built by Grumman, of course, and others built by GM. I wasn't aware of this difference until I took a look as some of the pics on the computer.

davegee