Wire Lugs/Guides on Helicopters

[BABAR]

for those of us without towers/pistons

For helicopters where the lugs have to go on the rotors, what are the pros/cons regarding weight, drag (etc?) for wire lugs/guides vs launch lugs.

One issue is that the rotors by definition have to rotate, thus the lug or guide, while parallel to the flight path in boost, becomes perpendicular to the direction of rotation on descent.

Also, is thinner wire always better? I know it would be lighter, but question if it might give more drag on the launch rod.

Tom

[Micromeister]

Tom:
Generally lugs are not used at all for HD models up to about F motor. the launch rod is usually threaded up between the rotors and fincan/body tube.
On occasion I have formed a single Kevlar forward Loop to pass a rod at the Hinge/rotor/body joint, stiffened with a tiny bit of CA. but even that was only on C and D powered birds.

Sorry this is about the only photo I have of a competition HD, usually more worried about timing then pictures.

After looking at my flight log I can again say without question I've never used a Launch lug on any Helicopter recovery competition model lower then F motor class. While a good number in the early years were flown from 1/8" stainless one piece launch rods, from about 1993 on, HD was almost always flown from a Piston or Piston/tower combination to be anywhere near competitive.

[JPVegh]

I've never put the lug on the rotor. I usually put it at a fin joint and then thread the rod up under the rotors as Micromeister describes.

I've started using pistons for most smaller competition rockets. Once you build one and get some practice with it you'll wonder why you didn't do it sooner. They aren't expensive to build from scratch or even in kit form for that matter. I now have MMX, 13mm and 18mm pistons. If your going to be competing I would recommend it. BTW, all of my pistons are based on Micromeisters MMX floating head design. My only problem with pistons is that I tend to forget to pack them for the launch.

[Micromeister]

I'll offer a bit more info concerning aft end LL on HD models.
Since the motor/fin can is already trapped fairly tightly by the burn string or clip held rotore, the area between the rotor vee and motor tube is fairly small making a lot of slop on the rod not that big a deal. Careful vertical placement on the rod as you attach the microclips will ensure vertical liftoff using only the forward guide to keep the model heading in the right direction. Where most of the movement comes from is at larger looser openings up forward between the rotors/hinge & model head. For Smaller motor models MMX, 10.5 and 13mm additional support or restraint is usually not needed. Larger 18 and 24mm motor mounts is where I've found adding an extra warp of 13lb 2strand Kevlar thread after wrapping the Hinges makes an excellent eye for an 1/8" rod to run through. Stiffening with just a minute amount of CA on a toothpick makes a pretty rigid, easy slide, low drag and very low wind resistant LL that for the most part is not going to cause much in the way of resistance to rotation of the deployed rotor disc.

Unless there is some really huge opening that must to be delt with on the aft end I would not suggest using a rear lug at all. Careful prelaunch postioning on the pad will surfice.

I also strongly suggest making yourself a couple quick and dirty Pistons that need be nothing much more then a 1/2" wooden dowel, a BT-5 or BT-20 body tube 12" to 18" long and a couple couplings to fit your tube size or sizes. Heads in 0 volumn pistons can be as simple as an expended motor casing that fits the tubing of choice. After you've eperimented with this quick and dirty 0 volumn pistons, it's an easy step up to produce nearly NO Tools Metal head pistons and from there get into a little more complicated "some tools required" Floating head pistons.
Seriously! Once you see how easy it is to build and use these launcher accessories you'll wonder why you didn't get into them sooner. If you need any question answered or plans let me know.

Q&D pistons can be a little on the frustrating side to get to work every time. Like everything the more we use something the easier it gets. Trust me also when I say learn to use your pistons, towers and other ground support equipment sometime OTHER then at a competition. With all the other things one has to worry about.. in the heat of the moment... During a competition event is not the time to be trying to make a new launcher work.

[MarkII]

Just to clarify, the floating head piston launcher was invented by Chuck Weiss and Jeff Vincent back in 1986.

http://mysite.verizon.net/wjvincent/...fhp1/fhp1.html

[jflis]

I took just this issue into account when putting together the Rose-A-Roc kit (the possibility that the builder wouldn't have access to a piston or tower.)

I have attached the two figures that show the attachment of a wire lug on the blade. A standard lug would be glued to the body/motor tube.

While this does increase drag, it isn't much. I've flown both with and without and did not record any duration differences that I would attribute to the lug (though I am sure that with enough tests a difference would become apparent).

Hope this helps!
jim

[Micromeister]

Just to clarify, the floating head piston launcher was invented by Chuck Weiss and Jeff Vincent back in 1986.

http://mysite.verizon.net/wjvincent/...fhp1/fhp1.html

That statement may not be quite correct Mark. I believe the floating head piston was "imported" from the Russian international team a year or two before that Naram R&D report. Don't recall exactly, but I'm pretty sure the USA Team guys I saw first testing their fibreglass tube versions were in June & July of 84 or 85. Not that it makes any difference at this point i'm sure George or one of the other Ol'e time internat fliers might be able to put a bit firmer time frame on it.

[Micromeister]

I took just this issue into account when putting together the Rose-A-Roc kit (the possibility that the builder wouldn't have access to a piston or tower.)

I have attached the two figures that show the attachment of a wire lug on the blade. A standard lug would be glued to the body/motor tube.

While this does increase drag, it isn't much. I've flown both with and without and did not record any duration differences that I would attribute to the lug (though I am sure that with enough tests a difference would become apparent).

Hope this helps!
jim

Jim:
Did you notice much rotor disc wobble or were the other rotors re-balanced to match the lug added rotor?

[BABAR]

Thanks gentleman
Hoping to post pictures of my latest competition helicopter soon
It has 4 rotors with a square cross section so will probably call it the Hyp2Bsquared
Since Jackson Tennessee isn't really near anything for competition, I'll let the REAL comp guys look at it and see if it merits attention

[jflis]

Jim:
Did you notice much rotor disc wobble or were the other rotors re-balanced to match the lug added rotor?

John,

Didn't rebalance the rotors as the added mass is such a small fraction of the total I didn't see the need. But, then, I'm not a competitor so...