Estes A-E Engine Test Stand

[kc5ngx]

Hello All!

I would like to construct a static engine test stand that will test Estes A-E engines. All I have found so far on the internet are plans for high power engine test stands. Can anyone direct me to a web site that has info on Estes type static test stands?

Any information most welcomed!

John Strunck

 

[Neil]

Dig a hole in the ground, stick the motor in it and press the button


Or, if you really want to be professional, take an old sawhorse, drill some 13MM, 18MM and 24MM holes in it, and let er rip!

Orrrr.... If you wanna get REALLY proffesional, make a stand with an adjustable weight, and make it so the motor is horizontal... Then it will spin!

if it were me, I would just stick em in the ground....

What exactly are you trying to accomplish?

 

[Ryan S.]

depends what you are trying to do. You can just put them upside down on a launch rod in the ground or on a stand and then tape them down. If you want max thrust there are other methods

 

[kc5ngx]

Neil,

We want to build a stand that will record time\thrust curves on a sheet of paper.


John Strunck

 

[Hospital_Rocket]

If you want to measure a thrust/time curve you are going to need two things.

1) A physical stand

2) A load cell

The stand can be relatively simple - a MMT epoxied to a piece of aluminum.

As for the load cell, now we are talking some money....

Here is a good place to start

https://www.aeroconsystems.com/electronics/loadcells.htm

However you will need a clean power source, some amplification, and a readout device. You may find the instrumentation difficult as you are talking about not much force for a very short period of time.


On the other hand, most of the information you may want is at:

https://www.thrustcurve.org/index.shtml


Please be careful as you are considering using rocket motors in a manner that can easily injure someone.

 

[BlueNinja]

There was a thing about a test stand somewhere in a book, let me look it up. I think it was called second stage:advanced model rocketry.
I cant find it.

 

[Ryan S.]

there is a simple way to do this (maybe not simple but less expensive) It involves putting the motor in a tube on a rail, lets say you put rail buttons (and this isnt the way you would actually do it but to keep it simple) on a tube and put a motor in this tube then slid it down the rail.

At the end of the rail there is a spring, there are some requirements for this spring; you need to know how much force it takes to compress the spring a certian distance (and simple tests will show you this). So the motor hits the spring, and off of this spring is an arm which is holding a pen and is pointed over a peice of paper (wrapped over something cylindrical)

So you get the cylinder to spin at a constant speed with the pen touching it, the motor starts burning and pushes the spring inward, wich also pushes the pen which gives you a line on your paper, you can find how much force by the height of the drawn line.

The other way would be to get a pressure guage, and put the motor on top of it, now put a camcorder on the guage. Burn the motor and analyze the footage. Using the frames you can see how much thrust is produced and at what time during the burn and make a graph

 

[Hospital_Rocket]

Ryan

Heep in mind a couple of things

First is Hook's Law - a spring may not be linear in its the force used to compress or extend it.

https://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/Work/DefinitionWork.html

Read the portion under variable work. The math is a little tricky,but the definition is rather straightforward.

Also, remember that this is over a very short period of time. You would need a elapsed time counter measuring in, hundreths of a second to get any meaningful data.

A

 

[Ryan S.]

I was thinking about that, but it was someone elses design. Maybe I misunderstood how it worked.

Maybe you can pull an idea from one of these.

https://www.aeroconsystems.com/ts_pics/ts_pics.htm

 

[Neil]

Theres some kinda scale they use for weighing birds. They put the bird in a bag, hook the bag onto one of the hooks on the scale, and hold the other hook in thier hand. Then the weight is listed on the side. Could you hook a motor up onto one of THOSE puppys? You would have to use a video camera or something to record the readings, and then copy them onto a sheet of paper yourself. In other words, Ryans idea might be better (brainstorming out loud here.... )

Search google for what you are looking for. That thing can turn up goodness knows what, and once in a while its helpfull

 

[kc5ngx]

To all who have replied to my previous postings,

I believe I have found the information I was looking for. After I purchase the parts, we will build a stand very similar to the one seen in the Jr. Misssilemen movie.

Thanks Again,

John Strunck

BTW, are there any Amateur Radio ops\Rocketeers in this forum?

 

[Neil]

Ham radio? theres one or two. Doug (N3TJM is his TRF name and Ham radio thingy) is one... Theres one or two others, but they havent posted here yet You could proabably ask him....

 

[edwardw]

I built a HPR test stand but I think you can also build one for LPR just as easy.

www.dataq.com

A $25 analog to digital converter with some cool software.

www.ebay.com

Get a load cell for the max thrust you want. Since you are not too worried about CATO's then a load cell is fine. For my EX motors I use a pressure transducer with hydraulic fluid incase of CATO - that way the sensor is protected behind the fluid.

www.mbrocketry.com

Lots of cool info - the link for amplifier schematics (you need this to up the output of the load cell is at)

https://www.mbrocketry.com/exp/exp_tools/exp_tools.htm

As it states on the page you can have them sent to you free as a sample.

Put all three things together with a stand and you have a working thrust stand.

HTH,

Edward