best length for a MMX tower launcher?

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hunterdude

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I am trying to get my local club to do a MMX contest...I want to construct a tower launcher to help stimulate some interest. From those experienced in such things, what is a good all around length?...also, I have an unbuilt Nanite glider kit, will a glider fit in a tower? I have not looked at the wing to pod distance so just wondering if it can be done.
 
I am trying to get my local club to do a MMX contest...I want to construct a tower launcher to help stimulate some interest. From those experienced in such things, what is a good all around length?...also, I have an unbuilt Nanite glider kit, will a glider fit in a tower? I have not looked at the wing to pod distance so just wondering if it can be done.

Gliders are almost NEVER launched from a tower. Most size gliders (Micro Max) Included need a bit more support then a single .049 or .050" x 9-12" launch rod. I usually use 3 rods. with the centeral 12-18" x .049" stainless rod and 2 shorter 12" "wing support rods out about 2" from center left and right. This scheme keeps the glider on the pad in the direction selected rather the rotating around the rod with the breeze. some use 5 rods with one above and below each wing along with the center LL rod:)

Tower rails need be no longer the 12" for most competition Micro Maxx models. I've designed and built a number over the years but have settled on a dual clear tube design with 3fin rails on one side and 4fin on the other. both a completely adjustable allowing model bodies from minimum diameter .281" T2+ size to BT-50 clusted models.

Below are a couple different designs i've build and used. All function fine for minimum diameter models but were not very user friendly adjusting for other body diameters.

Something else to consider. Most, if not all serious competition micro models can are ARE being flown from naked metal head or Floating Head piston launchers NOT towers. Theses pistons will increase over all altitude by as much as 7-10%.

PS: One page Plan's for the dual tube tower, Metal head and floating head pistons are available for free download over on the MicroMaxRockets Yahoo group board. They are in the files section under McCoy's Micro models in the equipment folder.

MM-Triangle Tower-a_Similar 3-fin tower topside photo_09-02.jpg

MM T3-2p3_Twin Tower_Comb 2pic 128dpi_03-10-05.jpg

MM T3-2p5-sm_Twin Tower_in use at Middletown_02-19-05.jpg

MM T3-2p6-sm_Twin Tower_Micro Comp Methods Demo Narhams Meeting_04-02-05.jpg

MM F-Head Piston-c_& 3pc telescoping WindScreen_04-18-09.jpg

MM F-Head Piston-d2_10in PD test model Sceen Up_04-18-09.JPG
 
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The adjustment of each rail individually could be eliminated by gluing a small rare earth magnet to the bottom of each rail, using a steel deflector and having the rail mounted by two arms that can pivot up or down with respect to the outer gantry or support. By the addition of a threaded rod and insert attached to the deflector plate, simply turning the plate, will cause it to ride up or down on the threaded rod. Each rail will follow this movement but spread open or close uniformly being held to the plate by magnets but allowed to slide along the surface of the plate, constrained by the two rotating arms. If you need to switch from three rails to four you would flip up two rails at the 120 and 240 positions and flip down three rails at the 90, 180 and 270 positions. Rails not being used are held out of the way by magnets mounted to the gantry or support.
 
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The adjustment of each rail individually could be eliminated by gluing a small rare earth magnet to the bottom of each rail, using a steel deflector and having the rail mounted by two arms that can pivot up or down with respect to the outer gantry or support. By the addition of a threaded rod and insert attached to the deflector plate, simply turning the plate, will cause it to ride up or down on the threaded rod. Each rail will follow this movement but spread open or close uniformly being held to the plate by magnets but allowed to slide along the surface of the plate, constrained by the two rotating arms. If you need to switch from three rails to four you would flip up two rails at the 120 and 240 positions and flip down three rails at the 90, 180 and 270 positions. Rails not being used are held out of the way by magnets mounted to the gantry or support.

sounds very interesting:
I'd like to see such a tower, do you have one?

Generally bottom only mounted rails regardless of mounting method, DO NOT remain aligned properly allowing the model to rattle back and forth on the way up retarding the forwards speed build up, or worse falling out between rails before reaching the top.
On 12" and shorter micro rails this may not be as obvious a problem as on standard 3 and 4 rail towers, but it is still a problem. There must be positive forward rail spacing support as well as at the bottom deflector.
Having built and tested 6 or 7 different rail mounting designs Individual rail adjustment has been by far the most consistant method beyond building a solid 3 or 4 rail tower for a specific given OD body size.
 
sounds very interesting:
I'd like to see such a tower, do you have one?

Generally bottom only mounted rails regardless of mounting method, DO NOT remain aligned properly allowing the model to rattle back and forth on the way up retarding the forwards speed build up, or worse falling out between rails before reaching the top.
On 12" and shorter micro rails this may not be as obvious a problem as on standard 3 and 4 rail towers, but it is still a problem. There must be positive forward rail spacing support as well as at the bottom deflector.
Having built and tested 6 or 7 different rail mounting designs Individual rail adjustment has been by far the most consistant method beyond building a solid 3 or 4 rail tower for a specific given OD body size.

The arms that pivot are located within 2 inches of the top and bottom of each rail in the case of a 12 inch tower with a third arm mid way on towers 36 inches+. The attachment points to the rail and to the gantry require that there be little or no side to side play . I have not completed such a tower (Micro Maxx) as yet, but have started one intended for low power rockets from BT-20 to BT-80. When this is completed and some experience gained I will report back. As you can imagine there are a lot of decisions still to be made.
 
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The arms that pivot are located within 2 inches of the top and bottom of each rail in the case of a 12 inch tower with a third arm mid way on towers 36 inches+. The attachment points to the rail and to the gantry require that there be little or no side to side play . I have not completed such a tower (Micro Maxx) as yet, but have started one intended for low power rockets from BT-20 to BT-80. When this is completed and some experience gained I will report back. As you can imagine there are a lot of decisions still to be made.


If I'm interperting your post correctly your using a pair of Up-Down Pivoting arms connected to your rails within 2" of the top and bottom of your rails and support structure. If this is the case the Magnets are unnecessary..actually in the way. as the pivots will grant all the adjustment needed to fit models from .448"(10.5mm) to BT-80. I just sold my Old competition Tower to a friend last year as I do not do much competition flying anymore.
Below are a few photos of this Tower which was also able to house 10.5 to 24mm Metal head or Floating head pistons. I used this Tower successfully at many local, regional and National NAR competitions placing or winning many a ribbon and trophy in the process.
Unfortunately when building towers for micro models the swing arm rail mountings are way more difficult to align and get to stay rigid side to side. That was the overriding reason my dual tube Micro Tower use dual spring loaded thumbscrew adjusted rail mounts. These proved to be more rigid and easily adjusted for different bodytube sizes T2+(.281" Mimimum Motor diameter) to BT-50 size micro models.

When you get your standard size competition tower built, please come back an post a couple photos so folks can get a better Idea of what and how your proposed tower works. Unfortunately it's kind of difficult to picture from your written discription. One picture or drawing is worth 10,000 words:)
Good Luck with your tower project, should be interesting.

Comp Tower-a1-sm_Outdoor Full View_03-16-91.jpg
 
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