Horizontal Deployment with Tomy Timer HDTT

Horizontal deployment is a system I created out of need. I wanted to have a reliable system that would deploy a parachute. Bruce Berggren and others had already been fooling around with Tomy Timers and I was getting tired of the unreliable nature of air flaps and other devices on FTC's so I spent lots of hours daydreaming and came up with this system. It seems to work, I hope it can work for you.
Here is a picture of HDTT in action ejecting a parachute from a FTC.
A Packed Chute ready to go.
Visible here are the two pins, one on each side of the deployment chute. They keep the securing rubber band from being pushed down by the air blast of take off and flight.
Tomy Timer secured with small wire.
Top View into the FTC. The tan thing is the 18mm ESTES Rocket tube used for the horizontal tube. The Tomy Timer is on the right. The knot seen at the top of the horizontal tube is the shock cord tied to the chute shrouds. The shrouds and shock cord are stored behind the chute. Several wraps of shroud lines around the chute are needed to keep it from expanding in the tube. The rubber band on the left is the securing rubber band that wraps in front of the ejection tube to the Tomy Timer. The rubber band barely visible at the bottom is the top of the vertical ejection rubber band.
Here is a general description of the action of HDTT as related to FTC.
  This is a copy of an email from me answering a question from Jurriaan van de Beek.
Hi Jurriaan,

Basically the FTC HDTT is similar to Ulrich's setup. The horizontal tube is a 18mm ESTES Rocket tube. There are two different timers out there that I have seen. The one that Ulrich uses is the larger of the two and I am not sure that it would fit in a FTC. To visit Ulrich's site go to:

The first step is to set the upper bulkhead about 8cm into the FTC. This leaves room for the HDTT. I cut my hole for the horizontal tube first so that the tube will rest on the bottle cap. Do not glue in at this point.

There will be room for the Tomy Timer to set next to the horizontal tube but it is a tight fit. Next drill the hole for the TT shaft to exit. I try to place the TT so that the bottom edge of the TT also rests on the bottle cap. I drill holes on both sides of the TT and wrap a very small wire through the holes and around the TT to secure it in place. (Don't get glue near the body of a TT, the gears and shafts seem to attract it)

Once the TT is in place it is time to secure the tube with PLP, Kalex, or something similar that will stick to FTC. Once dry trim the outside of the tube.

Ejection rubber band Vertical. Securing rubber bank horizontal to TT. I use rubber that can be purchased at hobby stores for use with free flight rubber band powered airplanes. It is very high quality, hold up well and appear to give more power to a given length than typical rubber bands. This helps in the tight area of an FTC.

One problem I encountered, which cost me an altimeter early on was the air blast blew the securing rubber band below the chute causing early ejection. I then came up with idea of sticking a needle on either side of the ejection tube to support the rubber band from being blown down. The needles were pushed through the FTC and secured to either side of the horizontal tube.

I use an ESTES 12 inch chute with about 6 inches or 15cm of shock cord. You will have to practice folding your chute really tight to get it to fit, but it will. You may question, is 12 inches or 30 cm a big enough chute? It allows the rocket to fall quickly, but has never caused damage on my FTC's.

In the record shots with Insane Air, I used a paperclip jammed into the gears to release the Tomy Timer. I like Ulrich's simple jamming of the knob, it is KISS and works.
This is text on HDTT improvements for FTC and Soda Bottles shared with the WR Thread.

1. To improve deployment and eliminate hang-ups in the ejection tube, make the tube slightly small in diameter in the back than the front. As the chute advances in the tube it becomes free and kick out to the length of the coiled hroud lines. This was not used in the middle school SO rocket and would have probably eliminated one of the hang ups we had due to wet chutes. When working properly, you should have no entanglement problems with HDTT since the chute should be at least 1 to 3 feet away from the rocket when it opens.

2. To reduce the hang ups, make the ejection tube from plastic tubing (ex. FTC) or paint poster board with lacquer to make it slick. Poster board is the material used to make tapered ejection tubes. Toilet paper tube and paper towel tubes also make great ejection tubes for parachutes up to 4 feet in diameter (except in the rain). The winning high school at SO Nationals used an FTC ejection tube.

3. Timers should be set to go off during assent or decent only. Never set the timer to go off at apogee. At apogee, when the rocket has little to no speed, if the chute is ejected down, the rocket can fall into the chute. If the rocket has forward speed either up or down, the possibility is eliminated.  In most applications on one and two liter bottles the timer should be set to go off at 2 to 2.2 seconds.

4. When using HDTT, the dynamics of the rocket changes allowing the rocket to use very small fins and maintain great stability. Since the cone and rocket are one piece  all the mass located in the cone give a 100% stabilizing effect Vs a loose cone dampening the stabilizing effect of the mass in the cone.

5. The timer can be adjusted in several ways.

      A. Drill two holes in the tomy timer knob and glue in two pieces of paper clip resulting in 4 posts to hook the rubber band to. In most situations you can use one hole resulting in 2 posts. On 1 and 2 liter bottles you can get by with one post. On the small white tomy timers (most common) .75 rotation results in an approximate 2.5 second deployment. One can vary the time of .75 rotations from less than 2 seconds to approximately 2.7 seconds. Small adjustments can be made using methods described below.

      B. You can also vary the time by changing the number of pre-turns of the tomy timer knob.

      C. You can further vary the time by changing the tension of the rubber band that attaches to the posts on the knob.

      D. In addition you can change the time by grabbing the restraining rubber band and pulling it away from the knob altering the tension.

6. Air flap release of the timer I think will become the preferred method. It is KISS. As I am able to share pictures on my web site, you will see the simplicity and reliability of the idea.

These methods will allow you to set the timer to any time from less than one second to over 15 seconds, with consistent accuracy approaching .1 seconds.