Lessons Learned during the launch.


Kipton Moravec
 

We made a couple of mistakes during the launch. Unfortunately in the excitement of launching we forgot some stuff we knew from our last launch 2 years ago.

The tethered launch works when we do it right. Unfortunately we did not do it right.

First thing. The two people holding the tether need to be farther apart, like at least 20-30 yards. That will help prevent the balloon from turning and causing the tether to twist. That is what happened on the first try. When we brought it back down I had to turn the balloon 1 revolution and it was O.K.

Second thing. All the payloads need to be off the ground before we let go of the tether.  If not they will drag on the ground and we do not want that. But that is what happened.

I should have said STOP. Let's spread out the two people on the tether, let out more string until all the payloads are off the ground, THEN let go of one side of the tether.

I knew better, but got lost in the fun of the launch.

We will do better next time and not lose any payloads at launch.

Kip


Roger Stierman
 

Like to add one more calculation, unless someone already knows this.
I noticed the lowest payload ( 1180 grams) was not going to lift off the ground until  at least the balloon was much higher. And it wouldn't rise until the tethers were longer. Calculate the vertical distance compared to the cosine of angle times the tether length. I estimate the angle was 45 degrees, depends on the wind speed and force on the balloon. I assume the stated measure of the lift force 6.8 kg and total payload 6 kg are correct. WA0VYU


On Sun, Jul 25, 2021 at 6:54 PM, Kipton Moravec
<kip@...> wrote:
We made a couple of mistakes during the launch. Unfortunately in the
excitement of launching we forgot some stuff we knew from our last
launch 2 years ago.

The tethered launch works when we do it right. Unfortunately we did not
do it right.

First thing. The two people holding the tether need to be farther apart,
like at least 20-30 yards. That will help prevent the balloon from
turning and causing the tether to twist. That is what happened on the
first try. When we brought it back down I had to turn the balloon 1
revolution and it was O.K.

Second thing. All the payloads need to be off the ground before we let
go of the tether.  If not they will drag on the ground and we do not
want that. But that is what happened.

I should have said STOP. Let's spread out the two people on the tether,
let out more string until all the payloads are off the ground, THEN let
go of one side of the tether.

I knew better, but got lost in the fun of the launch.

We will do better next time and not lose any payloads at launch.

Kip








AE5IB (Kip)
 

I am pretty sure we still had string on the spool. I do not think we were out. If we were, then we need a longer string. I have more string if that was the case.

We are also going to make the payload separation a little closer.

Kip

On Sun, Jul 25, 2021 at 7:23 PM Roger Stierman via groups.io <rogerstierman=netscape.net@groups.io> wrote:
Like to add one more calculation, unless someone already knows this.
I noticed the lowest payload ( 1180 grams) was not going to lift off the ground until  at least the balloon was much higher. And it wouldn't rise until the tethers were longer. Calculate the vertical distance compared to the cosine of angle times the tether length. I estimate the angle was 45 degrees, depends on the wind speed and force on the balloon. I assume the stated measure of the lift force 6.8 kg and total payload 6 kg are correct. WA0VYU


On Sun, Jul 25, 2021 at 6:54 PM, Kipton Moravec
<kip@...> wrote:
We made a couple of mistakes during the launch. Unfortunately in the
excitement of launching we forgot some stuff we knew from our last
launch 2 years ago.

The tethered launch works when we do it right. Unfortunately we did not
do it right.

First thing. The two people holding the tether need to be farther apart,
like at least 20-30 yards. That will help prevent the balloon from
turning and causing the tether to twist. That is what happened on the
first try. When we brought it back down I had to turn the balloon 1
revolution and it was O.K.

Second thing. All the payloads need to be off the ground before we let
go of the tether.  If not they will drag on the ground and we do not
want that. But that is what happened.

I should have said STOP. Let's spread out the two people on the tether,
let out more string until all the payloads are off the ground, THEN let
go of one side of the tether.

I knew better, but got lost in the fun of the launch.

We will do better next time and not lose any payloads at launch.

Kip