Well, I am resurrecting this very old thread as I finally launched the Tao for the first time last weekend.
Since the last post, I added 0.25 oz. nose weight and found out that there were 2 problems with the nested staging for the Tao.
- I found out that the engine hook on the sustainer prevented the 18mm sustainer motor from nesting inside the 24mm booster motor. I decided to simply cut off the motor hook and use tape retention.
- Also discovered that once the hook was cutoff,the sustainer motor assembly was still about 1/16" too long to allow the coupler to fit completely fit together. I added a 3/16" ring of BT-60 tubing at the base of the coupler to fill the gap. Not sure if this was due to changes in the D12 motor since the Estes DOTM was published or whether I was off on one of my dimensions
I had been waiting for a nearly windless launch because I wanted to take wind out of the equation as much as possible if the rocket had an unstable flight. Last weekend, our club was having a night launch, and about 7:00 (still well before sunset) the 4-7 mph winds calmed completely and we had dead air with occasional 1 mph "gusts". Since I had the rocket with me and prep is very quick I decided it was time for it's maiden launch.
I got raised eyebrows from the RSO when I told him it was a finless rocket, but once I explained the concept behind it and told him I had a working sim for the rocket, I got a "Yeah that's a sound concept" and the launch was approved. After calling for a "heads up launch", my friend Gary gave the countdown and pushed the button. The rocket leaped very quickly off of the pad.
There was very noticable spin, but it was impossible to quantify the exact spin rate. Simulations showed that the rocket was expected to reach 18 revolutions per second. I was surprised at how high the rocket was at staging. I checked later and saw that sims showed staging was predicted to occur around 350' and I would concur from visual observation that looked very probable. Staging looked clean, but immediately after staging there was visible coning of the sustainer that got increasingly severe during the burn. Once the burn ended the sustainer quickly entered a flat spin while still rising during coast. Several people visually estimated the altitude to be about 600-700', well short of the simulations prediction of approximately 1150-1200'. This is understandable and to be expected due to the added drag from the coning and flat spin.
Video showed that the motor gave about the full 5 second delay, and the ejection charge appeared to be after apogee, nose down, still in a somewhat flat spin. The piston fully deployed, but due to the flat spin, the rocket was not spinning in the manner needed to deploy the wound up chute. It also appeared that the chute got tangled on the swivel and these two factors prevented the chute from deploying. Luckily with the rear piston deployed the sustainer was no longer aerodynamic, and came down with a flat fall rather than ballistic trajectory. The sustainer was recovered about 30' from the pad, and the booster was recovered about 100' from the pad.
I missed the booster falling, but the parachute did deploy. Somehow one of the fins did break on impact however, and was found about 6' from the booster.
I will try to post the video, but it is not very clear.