A8-3 Model Rocket Motor Vs 5HP ShopVac, Meaningless Experiment?

With all the debate about rockets working/not working in a “vacuum”, I devised a little experiment.

Below will be two videos linked to. The linked to videos are two different views of the same rocket motor ignition.

A 5 hp ShopVac is hosed up to the exhaust end of an A8-3 rocket motor with a maximum thrust of 10 Newton’s. The rocket motor is in a cheap Phantom Blue model rocket.

The model rocket motor by some individual’s logic will have all its back pressure removed, and not thrust forward.

I do hope this is more meaningful that people trying to show rockets don’t work in a vacuum by venting balloons into a vacuum cleaner.

In short, A8-3 rocket motor Vs 5 hp ShopVac. The model rocket powered by the A8-3 pulls away from the “vacuum” of the hose with no hesitation. The maximum 10 Newton’s of thrust kicked the bottom of the 5hp vacuum.

A8-3 Rocket Motor VS 5HP ShopVac

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A8-3 Rocket Motor Vs 5HP ShopVac two

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Rocket motors are not supposed to work in a vacuum, the rocket was not in the vacuum, if you stuck it in there, it could not fly away. Cool experiment, completely immaterial, but at least you did an experiment

a reply to: rickymouse

I would put it in the “vacuum”, but couldn’t find a see through ShopVac.


I guess I could have put the rocket in my canister shark vacuum?

Generally solid rockets don't ignite in a vacuum due to not being able to build up enough pressure to sustain combustion.
A vidjeo from a somewhat prominent youtuber explains this, and manages to ignite a solid rocket in a vacuum chamber with a simple caveat.
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and one relating to creating fire in a vacuum.

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The problem is, all liquid/gas rocket engines create their own pressure with turbopumps in order to ignite in their combustion chamber, negating the issue of lack of pressure.

that being said... that vacuum sure took it like a boss

a reply to: neutronflux

There are grown-ups who believe that earth is flat. So I guess it is not surprising that there are also grown-ups who believe that rockets don't work in a vacuum.

If you had soaked the vacuum hose in gasoline and put gasoline in the shop vac, everything would fly.

Disclaimer: I am not a rocket scientist or a vacuum cleaner scientist. Don't try the above at home (don't even try it away from home).

a reply to: neutronflux


Ummm...effing troll...

I like it...







YouSir

a reply to: neutronflux
I just noticed the secret launch tube that you have built in under your picnic table... pretty sweet!

I am getting closer to using a clear PVC pipe as a “vacuum” chamber. Until then.....

Estes 1/4A3-3T rocket motor against 5 HP Shopvac.

Picture below for scale.



1/4A3-3T size vs the A8-3 rocket motor used in the first Shopvac experiment.

For this experiment, I used an Estes Mosquito rocket and a 1/4A3-3T rocket motor. The 1/4A3-3T is what I think is Estes smallest engine in current production.

The 1/4A3-3T specs:
Total impulse: .625 N-sec
Max Thrust: a whopping 4.9 Newtons
Thrust Duration: .25 Sec

The 1/4A3-3T with its 4.9 Newtons out workers a 5 HP Shopvac to launch from a “vacuum” and lack of “back pressure”

The test was done twice. One flight with a blue tape band to hold the tube to ride the wire. The second flight was with a black tape band.

Picture of entire thrust of the blue band rocket flight consumed by the Shopvac

Link to the blue band flight video

1/4A3-3T Rocket Motor VS 5 Hp Shopvac - blue - right - short
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Picture of the entire thrust of the black band rocket flight consumed by the Shopvac

Links to the black rocket flights

1/4A3-3T Rocket Motor Vs 5 Hp Shopvac - black - left side
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1/4A3-3T Rocket Motor VS 5 Hp Shopvac -Black- right side
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The 1/4A3-3T max thrust of 4.9 Newtons without hesitation takes off from the “vacuum” and “no back pressure” created by the 5 Hp Shopvac in its suction hose.

Links to the A8-3 original flight VS 5HP Shopvac

A8-3 Rocket Motor Vs 5HP ShopVac two
www.youtube.com...

A8-3 Rocket Motor VS 5HP ShopVac
www.youtube.com...

Below is a diagram of the Estes rocket motor construction