Rocket Launch Failure July 24, 2021

Подробнее о видео

If you are interested only in the launch, look at the 6th minute
You will see the footage from the three cameras, including the rocket camera. You will see how, after running out of fuel, the first stage was separated and the rocket gradually goes into horizontal flight.

At first, we could not find out the reason for the change in the trajectory of the rocket and its transition to horizontal flight in almost no-wind conditions. Just in case, for the next launches, we replaced the flimsy launcher from Estes with a reliable photo tripod with a large tripod head and a 4.75 mm in diameter and 1200 mm long rod. Later we made several calculators (), which helped us to find the reason for changing the trajectory:

The analysis of the video taken by the rocket camera showed why that launch on July 24, 2021, was a complete failure. Several reasons led to the failure:

1. The Estes C6-0 booster stage motor is designed to lift only 113 g while the Estes Loadstar II two-stage rocket with two engines weighed 113 + 13.9 + 23.1 = 150 g. That is, even without any additional load, the rod separation velocity determined by our calculator is only 8.7 m/s, which is unsafe. That means it was not worth trying to launch the rocket with this engine even without any additional load although this is the engine indicated in the instructions for this rocket. Link to the calculations: .

2. We installed a 27 g camera as an additional load on the rocket and its weight with two engines now was 140 + 13.9 + 23.1 = 177 g. The rod separation velocity determined by our calculator is only 6.4 m/s, which is half the recommended speed. That means, it was not worth trying to launch the rocket with this engine, but we tried. Link to the calculations: .

3. The Estes C6-0 motor was supposed to burn for 1.86 s, but in reality (determined from the video) it burned for 2.7 s. That is if the amount of propellant was as stated in the specifications, the motor thrust was 1.5 times less than specified. We measured this time using the footage taken from the rocket camera (160 frames at 60 frames per second).

4. The actual rod separation speed measured using the camera footage was only 3.6 m/s, which is very low. Therefore, by the end of the operation of the first stage motor and by the time the second stage engine began to operate, the rocket nose cone has already been pointed toward the earth.

Our five-year-old granddaughter assembled the rocket for five days, a couple of hours a day. The hardest part was her struggling with simple fractions for dimensions in inches and decimals for dimensions in millimeters. We dealt with fractions before, but here it was useful to show our granddaughter why simple fractions are needed in technology — she is no longer interested in dividing five apples among four people.

The rocket: Estes Loadstar II with C6-0 and A8-3 engines. Rocket weight 140 g.
Weather conditions:
Clear sky
Wind 3 km/h (1.86 mi/h, 0.83 m/s),
Wind gusts 7 km/h (4.31 mi/h, 1.94 m/s)

Chapters:
00:00 Making the Rocket
04:13 Preparation to Rocket Launch
05:28 Countdown
06:03 Hitting the Fence

Music from the YouTube Audio Library:

Stellar Wind by Unicorn Heads
Meditation Impromptu 03 by Kevin MacLeod is licensed under a Creative Commons Attribution 4.0 license.
Source:
Artist: