Airstart Timers and Questions

[Rocketmaniac]

Working on my HPR Cluster rocket, I need to make some discisions about how to fire the outboards...... (See the following threads for the build progress)

https://www.rocketryforum.com/showthread.php?s=&threadid=12219

Right now I am thinking about building a small compartment between two of the fins to hold a small timer. Perfectflite is the brand I think I am going to buy.....

Questions;

1. Can these timers actually fire an ignitor by themselves?

2. Will one timer fire two ignitors? or do I need to get two timers?

3. How do you ensure that the ignitors (in the outboards) don't slip out a little when the main fires? (thus making impossible to start the outboards)

These are all the questions that come to mind right now.... More might come up later.....

 

[Rocketmaniac]

The two model numbers I am looking at are:


Perfectflite UT2A $24.95
Perfectflite MT3T $34.95

 

[Rocketmaniac]

I've read a little more and it seems to me that only difference between the UT2A and the MT3T is the type of wiring connection. The UT2A has solder pads and the MT3T has screw-down terminal blocks. I am correct?

 

[GlassfibreMan]

Yes you are right. I have the MT3 with G switch. According to the manual it should fire two igniters such as DaveyFire, Oxral, or dipped providing use use the correct battery. The recommended battery is the 9v N6PT NiCad which will fire 5amp and maintain a voltage of 5.6volts during firing.

The DaveyFire requires 1.0 amps (x 2 in your case)
Oxral requires 0.5 amps, (again x 2)
Dipped varies from 0.5 amp - 2amp

All of the above are within the capacity of the N6PT. You can buy that battery from Perfectflite with your timer.

As for how do you secure the igniters, that's for someone else to answer, 'cos I'm not sure.

 

[n3tjm]

I got a Missileworks Pet2 timer for my Magnum. I was going to use it with channel 1 used as airstarts, and channel 2 for drogue backup... I did not have it in my Magnum on its last flight... which would of prevented this from happening (From CMASS mailing list):

"We had some pretty horrible flights last Saturday all of which would have been less frightening if they weren't into the parking area or at the condos. Most of the bad flights were caused by trying to adjust for a wind that was blowing in the wrong direction. In the future we're just going to have to face the reality that winds blowing from that direction are going to mean a long walk for recovery. We also need to make life easier for the RSO and LCO people. The person checking in your rocket can't tell if your electronics are going to work. If a safe flight depends on their operation they need to be tested ahead of time. It's also pretty difficult for the LCO to tell if pad C is pointed in the right direction. We can't be dropping big stuff into the condos and houses. Saturday's launched caused a call to the police department, fire department, and power company. Keep in mind that the Town of Amesbury has no obligation to let us use the field. The minute we become a thorn in their side we're history."

I never had a failure of that altimeter (the drouge did not fire), and the battery was a fresh one installed that morning (checked with a meter)... next time though.. that timer will go for a ride...

 

[Rocketmaniac]

Originally posted by GlassfibreMan
According to the manual it should fire two igniters such as DaveyFire, Oxral, or dipped providing use use the correct battery. The recommended battery is the 9v N6PT NiCad which will fire 5amp and maintain a voltage of 5.6volts during firing.

Great news!!! This means I will only need to buy one timer......

Originally posted by Snaquin
Although you didn't mention the MT3G you should consider it. For eight dollars more than the cost of the MT3T it has a G switch integrated into the timer board as GlassfibreMan mentioned.

I saw the MT3G but was figuring I had to buy two timers, so the extra $8 ($18 above the UT2A) was a good bit more..... I also did not understand the real purpose of the G switch...... Now that I do, saving a few dollars doesn't seem as important.......

Thanks

 

[Rocketmaniac]

Well I have placed an order on the Perfectflite website. I decided to follow Snaquin's suggestion and went with the MT3G. I also got the recommended battery and a battery charger.

I did have a problem with the website and will have to get my order straight. The final screen of the ordering process told me I had to re-start my order. So I did, same error. Now I receive (2) separate "order confirmations" (I am able to spend $73.35, but $146.70 is too much)

 

[jraice]

That is weird, twin timers lighting the same time? The more expensive timer is not only physically different with connections, I talked to perfectflite, it also has more "juice" and can light more then 50 e-matchs when using the right battery, I wouldnt try that but I dont see why two timers is necessary, it is a waste and will also make the launch less reliable (if one timer fails rocket crashs, with a single timer, if it fails you can just dont have an airstart). Plus I am not sure one timer can light even one "ignitor", e-matchs would need to be used probably and it can light way more then two e-matchs (freedom won had one of those timers to light two e-matchs for a perfect airstart of 2 J400s).