Firing a torpedo?

[ramius-ii]

Hi All!
The first post did not include this text? So I will try it again!
I have been looking at how scale torpedoes are fired on Frank Ricucci website under “Operating Instructions for Torpedo System.doc” at http://www.modelbrass.com/torpedoes/torpedoes.htm . I am a bit lost as to how the system is constructed since it lists using 2 tubes. “1. Outer tube is brass tubing with ID two sizes larger than torpedo diameter. 2. Inner tube is brass tubing with ID one size larger than torpedo diameter.” One tube and the breach at the end make sense. Why would a second tube be necessary? That is, isn’t just the outer tube required for holding the torpedo? Thanks, Ed

[Wheelerdealer]

Hi Ed, I guess the

Hi Ed, I guess the tubes that are 2 sizes larger are bonded into the hull and form the open end facing the pond. The tubes that are one size larger, now containing the primmed torpedoes are inserted into the 'outer' tubes. This way you can charge the topedoes outside the hull without removing the sub from the pond and standing it on its nose (torps will need to held head down to be filled with liquid propel)

How are all those sub toys coming along? You have one willing field tester here

Ramesh

[ramius-ii]

Hey Ramesh! http://www.subcommittee.com/forum/icon_biggrin.gif
How are

Hey Ramesh!
How are you? The "toys" are coming along great! It a short time the final lens should be determined for the periscope! I had to add a prism to the optical path. When it was added, focus went away so there need to be one more lens to bring the picture back into focus. Without the prism, the picture is great, even at 1 meter underwater and 100 meters away! So, I thought I would do something with the torpedoes. I just became stuck trying to find the details on constructing the firing mechanism. Since this has been already done, why re-invent the wheel? How have you been doing? Best, Ed

[mike dory]

Torpedo firing

Ramius - Might I ask, in what scale is your torpedo? There are a few differnt ways to fire off a gas powered torpedo, however, some requier a scale of 1/32 others need at least 1/48 and still others need 1/72 I want to wish you the very best in your project.... Mike Dory

[ramius-ii]

Torpedo

Hi Mike!
The torpedoes are 1/96 scale or .375" in diameter and about 4.125" long. I designed the "fins" with Autocad then had the design printed by a 3-D plastic printer which gives you a mold master. The size did not allow for a "fill" valve so I basically modified a combination of the designs by Dave Merriman and Frank Ricucci. What I completely missed when I looked at the picture on Frank's site it was a picture of an 8 torpedo system! When I saw 8 control valves and not all 8 torpedoes, the conclusion was that 4 valves were to fire torpedoes and 4 to load torpedoes! I will probably have to change to a different blend of coffee!

[mike dory]

Torpedoes

Raminus - 1/96 scale, well that getting right down there. I would think that having all that weight of those control valves in the nose of a 1/96 scale boat would be a problem not easly overcome when you go to trim your boat. I myself have never had working torpedoes in such a small scale. I look forward to seeing how you over came the challenges. My very best wishes..... Mike Dory

[ramius-ii]

Torpedo

Hi Mike!
Thanks and the valves only weight 2.25 ounces each and with 4 torpedoes, this is only 9 ounces. In the Typhoon there is a space next to the main power battery reserved for a receiver battery. Since the receiver operates from the main 12 volt battery, I loose the weight of the second battery and replace this weight with the valves! The torpedoes themselves are fairly easy to work with; the biggest difficulty is the size of the exhaust tube! It starts with a .0345” I.D. aluminum and then is reduced with three needle tubes to become .0067” exhaust hole! The breach mechanism has a .0625” hole for the torpedo exhaust tube that has a #3 o-ring and then becomes a 10-32 female hole for the compressed air fitting. The compressed air hose fitting also compresses the o-ring for a tight hold on the exhaust tube. While the air pressure from aero-duster is measured at 50 psi all testing has been done at 85 psi for a margin of safety. As for boat trim, I try to keep all weight towards the center and as low as possible!

Best, Ed

[cstranc]

I had a hard enough

I had a hard enough time getting a 1/70 scale torpedo to float. I had to minimize the amount of resin in the nose and tail fittings. I was using thin wall aluminum for the body of the torpedo.

Any chance of uploading some pictures? I would love to see the torpedoes and launcher.

Chris

[ramius-ii]

Hi Chris,
Sorry for the delay

Hi Chris,
Sorry for the delay in answering I was trying to figure out the best way to provide some pictures! Here are the exhaust tubes that are used from largest to smallest. The largest is 1/16 O.D. x .014 I.D. The next three are stainless steel hypodermic tubes in sizes such that they all fit inside each other to reduce the final outlet/fill hole to .0067"


The launch tubes are one size larger that the torpedo. I like things compact so the launch tube has a piece of hex rod drilled at a right angle to provide air at the rear of the torpedo (the large tubing is launch pressure). The smaller tubing is the fill tubing. Just below is the "breach disk" with a hole one size larger that the 1/16" tube of the torpedo. It is drilled so that there is about 1/32" of the small hole that then becomes the 10-32 tapped hole for the hose fitting. Due to the internal lenght of the breach disk, you can fit one or two size 3 o-rings inside the breach disk and then compress them to hold the torpedo firmly.

The nose of the torpedo is trimmed to have minimal weight and in the picture the fin assembly is much longer that what is actually used. The reason it is so long is so it can be chucked up into the lath to dill the hole for the exhaust tube. One the exhaust tube is drilled, then the fin assmbly is trimmed down quit a bit. I have been using T-88 epoxy, a little extra inside the torpedoes body, then on the surface to be glued, then standing the torpedoes up so the epoxy will add a thin addition seal.



Thats about it, I am still thinking about weather I would wish to incorporate a sensor so you could not accidently fire a enpty tube and at the same time it would shut off the launch air pressure once the fish has left the tube.

Best, Ed