# Good altimeter for ESTES rockets?

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Hello,
Anyone make a good altimeter for ESTES rockets?

Brian

#### cls

##### Well-Known Member
I bought a PerfectFlite miniALT/WD, which is close to the Alt15K but includes a couple circuits for ignitors. overall I would say good product for the money.

things I like about it: very tiny, will fit in BT50; good quality board, parts, and soldering; decent design. seems to be accurate. runs forever on 9v battery. has a configurable low battery alarm - great feature which goes with the wide variety of power (voltages) it will run on.

things I do not like about it: why didn't they use Morse code for beeping out the numbers? the max altitude reported (beeped) can be way wrong because of the pressure changes from the ejection - look very carefully at the downloaded data. the software in the download kit is extremely basic. the downloading is not always reliable. I wasn't happy with the graphs it draws. be prepared to write a spreadsheet if you want derived data such as accelleration and velocity info.

all the above seems to be par for the course with altimeters these days.

(I downloaded in to my laptop which does not have a serial cable. putting all this together, eventually caused the 1st BSOD on that laptop. I am pretty sure it was the Radio Shack serial->USB adapter software.)

#### teflonrocketry1

##### Well-Known Member
You could try the altimeter from Estes that is available on their Max Trax starter set.

https://www.estesrockets.com/products/product366.html

You can usually fin this starter set discounted to around $30.00. This is a good deal since most altimeters cost more than twice that much. Bruce S. Levison, NAR #69055 #### solrules ##### Well-Known Member Originally posted by teflonrocketry1 You could try the altimeter from Estes that is available on their Max Trax starter set. https://www.estesrockets.com/products/product366.html You can usually fin this starter set discounted to around$30.00.
This is a good deal since most altimeters cost more than twice that much.

Bruce S. Levison, NAR #69055
...Of course, that is not a real pressure-sensitive altimeter: just a timer that starts at apogee until it hits the ground. Using the physics equation:

displacement = 1/2 * 32fps/s * time^2

you can get the altitude. If you can retrofit this nose cone to your estes rocket, you can have a fairly accurate, cheap altimeter.

##### Roving Rocketeer
consider this a vote for perfecflites minialt/wd

fits in a bt 20 works well, although i haven't been able to download any data yet, haven't been able to get a usb/serial adaptor to work with osx yet. of course, i've only tried one so far. the joys of using a new operating system otoh, it never crashes

#### edwardw

##### Well-Known Member
Originally posted by cls

things I do not like about it: why didn't they use Morse code for beeping out the numbers? the max altitude reported (beeped) can be way wrong because of the pressure changes from the ejection - look very carefully at the downloaded data. [/B]
If you are getting messed up data from the ejection charge then you are not sealing the electronics bay enough. I use two o-rings on each end of my bay and have all wires running through the bay sealed with silicone. On the bolts that run through the bay I use a rubber washer beneath the nut to seal it. I have not had the problem with the data being skewed because of pressure, but I do seal the bay very well.

Edward

#### cls

##### Well-Known Member
Edward, thanks for the o-ring idea. I will try that on Saturday.

I just figured it was some (motor ejection) pressure getting in the vent (11/64" in a LOC 3" x 10"? altimeter bay)

#### edwardw

##### Well-Known Member
When I do my vents I space three equally around the BT. Also, I use my altimeter bay (usually a coupler) to size the holes. Then I make the holes in the airframe about 1/16 bigger - so that if it is misaligned then you are using the coupler to size the static ports, not the airframe. And if some charge gets by the o-ring, I'm hoping that it will vent out the airframe before going into the alitmeter.

I also used two pieces of 1/4 5 ply, and then routed a groove in them for the o-ring. When they were placed together it made a nice place for the o-ring to seal. I find now that I have to twist the bay into place rather than just pushing it.

Edward

#### Gus

##### Well-Known Member
Ok Guys,

I have zero experience with altimeters. Let's say I buy a Pico, it's really small and reasonably priced (all I'd really like to do is verify altitude vs. my RockSim simulations).

Do I then have to build an altimeter bay into every rocket? Can I build a single bay and move it between rockets? Truly, I have no idea how these are used.

#### teflonrocketry1

##### Well-Known Member
Gus,

Altimeters are usually placed in a vented payload section, sealed off from the ejection charge, and protected from direct wind currents. I typically convert the forward third of a rockets air frame to a payload section for this purpose.

The vent holes are usually placed a few body tube diameters aft of the nose cone to body tube junction; four body tube diameters is recommended for high speed models. For details take a look at the notes on mounting and installing an Adept A1 altimeter at:

Bruce S. Levison, NAR #69055

#### cls

##### Well-Known Member
you can just jam the Pico in a payload section with some foam. you do need to have a vent though. and the foam can't block the vent and the sensor on the altimeter.

or you could mount the Pico more securely in a a nice "altimeter section", made out of a length of body tube and a coupler at one end. this would go between the nose cone and the top of the rocket. it could be moved between rockets easily.

#### Fore Check

##### Well-Known Member
Has anyone tried the little altimiter available from Apogee? I saw it on their website last night. It fits insided a BT50 and costs \$75.

#### RocketboyG80

##### Well-Known Member
The one on Apogee's site is made by PerfectFlite (the apogee reporting only version).