Deployment Altimeters vs. Timers

[ghost]

Hello,

I've just gotten started in mid/high power rocketry. I've built the LOC Norad and the PML Pit Bull (3" diameter). I was thinking of building a custom rocket with either electronic deployment, airstart, or staging. I don't want to spend too much money. I was thinking of getting the PerfectFlite HiAlt45K dual event altimeter or the PerfectFlite miniTimer3. I was going to use Pyrodex instead of BP. Which should I get? Thanks!!!

[ghost]

Any suggestions? Thanks.

[tbzep]

When I was into HPR, I always used a duel event altimeter. I used an Adept with events at apogee and at 250 ft AGL. A lot of people were afraid of the low second event, but I had 100% success with it over the years in rockets as small as 2" dia. up to my 12' tall 1/2 scale Aerobee Hi. I've still got two of them. I should try to sell them, but who knows if I might want to get back into the big stuff someday.

If you only plan to choose one, I think you will get more use out of the altimeter. You can use it on every flight, even if it's just to find out how high the rocket flew. You won't be wanting to airstart or stage on every flight, so the timer might not be as useful. If you wanted to use the timer for ejection, you still have figure out what to set it at, whereas the altimeter takes care of it for you. However, if you can afford to cluster AP motors, you can afford to buy both devices. The timer only costs about the equivalent of one "I" motor, so fly one less rocket next time you go out to the field and you will have saved enough for the second toy. :)

[ghost]

Thanks for the advice. It is even possible to air start/stage with an altimeter, though?

[tbzep]

Thanks for the advice. It is even possible to air start/stage with an altimeter, though?

I don't know what the new altimeters have, but my old Adept only fires a charge at apogee and then a second event at 250 ft AGL, so it's impossible to use it for staging. Some of these new ones may have multiple features built into them for all I know.

The timer is cheap compared to motors, and it can be used over and over. If you can afford to fly AP clusters, you can buy both the altimeter and the timer. ;)

[ghost]

I think I'm going to go with a timer. Altimeters are too expensive (especially because this would be my first computer controlled deployment and if something goes wrong... that would be bad :( ). Which timer do you recommend? Thanks.

[heada]

I have flown both altimeters and timers(Missile Works RRC2, PerfectFlite MAWD, PerfectFlite HA45, PerfectFlite UT2A, PML AccuFire). I would highly recommend the altimeter over the timer for almost every use.

To answer the question about if an altimeter will do air starts/staging, there are altimeters on the market that will do air-starts and staging but they are commonly called flight computers and will do just about anything for a number of "events" The starting price for a flight computer is in the $150 range and I've seen them as high as $650 but those will do 4 events and download telemetry.

A timer is normally good for 1 event (the amount of time you set) and that is all. An altimeter is normally good for 2 events (apogee and altitude after apogee). A timer normally has more output to the pyro channel so it can fire a wider range of charges (e-matches as well as igniters) whereas an altimeter is almost always restricted to a low current e-match.

If I had to choose one device, I would go with the altimeter. (PerfectFlite MAWD is my choice) They are just as prone to problems as timers (meaning they only have problems when I forget to arm them) and they have more features (dual deployment and recording) and I use them even when I use motor ejection as they are a really good backup system. Yes, they are more expensive, but if you're going to be spending money on electronics, why not get the best bang for the buck.


-Aaron

[ghost]

Thanks for your help. This looked intriguing: http://www.lokiresearch.com/arts.asp

Have you ever heard of it? It costs $180.

Thanks!

[heada]

Yes, the ARTS is a very good Flight Computer (more than just an altimeter) but the price shows it too. From what I remember, the ARTS is a 2 event FC that can allow you to set the events to either takeoff, motor burn out, apogee or alt after apogee. This would satisfy your staging requirement and give you the ability to deploy the recovery system at apogee (or use motor ejection at apogee and use the FC for dual deployment) I think they are coming out with a new FC that will have 4 events, but I don't remember much in the way of details. Also, the ARTS are VERY hard to get ahold of. Seems like everyone is sold out of them.

Simple timer = $35
Good altimeter = $100
Flight computer = $180

Until you get into some seriously complex flights, I still think the basic dual deploy altimeter is the best bet. If you want air-start/staging AND dual deploy, then a FC is about your only option (unless you use a combo of timer+alt, which I've done...and thats fun too)

If I were to purchase a flight computer today, I would go with the G-Wiz MC2 Its a full flight computer with 4 programmable events all for about $200.

http://www.gwiz-partners.com/html/g-wiz_mc2.html

-Aaron

[ghost]

Hi,

Has anyone ever heard of https://aaarocketelectronics.sslpowered.com/Pages/Products.htm
????

Thanks.

[Ltvscout]

Hi,

Has anyone ever heard of https://aaarocketelectronics.sslpowered.com/Pages/Products.htm
????
New company, new product.

[heada]

I think they're still only accepting pre-orders. The altimeter looks really nice but its fairly large. There was some discussion of it on TRF.

-Aaron