Single use delay time most often used

When deciding to stock up on composite single use F & G motors what proportion do you choose between low, medium and high delay times? Obviously, it depends on the rocket. Just curious if there is a preponderance of one over the other.

I always get the longest delay, then use the Aerotech drill tool to reduce the delay to whatever I need.

If you don't have or want to get the drill tool, you can use a 3/16" drill to reduce the delay (1/32" depth/sec removed). Instructions here.


David

Mid power 7sec. High power 10 (AT - medium) are the most common for me.

He asked about single use. Of course, we have to guess if that is the normal non-adjustable single use or the newfangled adjustable type, but since he asked what delay times we choose, and the adjustable type of single use ONLY come as the longest, I will have to conclude that he is asking about normal everyday set dealy time single use motors.

Wizard said:

I always get the longest delay, then use the Aerotech drill tool to reduce the delay to whatever I need.

If you don't have or want to get the drill tool, you can use a 3/16" drill to reduce the delay (1/32" depth/sec removed). Instructions here.


David

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Based on what I see checked in at launches, the most common are medium delay times in medium sized models. In other words, if the F motor has a -7, -10 and -13 available, the -10 is most common.

BUT, many people who buy at a brick and mortar store will often buy 'whatever is left hanging on the peg' and that often means wayyyyy tooo loooong of a delay time. A club with good safety check will catch that and save the person from a stripped chute or zipper (or a crash) and find them the correct delay time motor.

Also, i still see people who buy the biggest number because they really do not understand the motor code and they think the bigger number on the end means it is more powerful. And I saw a TARC team on Sunday that thought that the F23 had more power than an F20 because 23 was bigger than 20. The F23 has less total impulse than the F20. I explained it and gave them a printed copy of the NAR cetified motor list so they could reference the total impulse of the different motors.

Sorry, I wasn't clear. I was referring to the old style SU non-adjustable delay types. Thanks for the responses so far.

I'd look at my fleet - short/fat draggy and or heavy rockets - go shortest. More slender "normal" rockets - medium delay. Light minimum diameter types - long delay.

No help here. I can count on one hand the number of SU motors I've flown in the last 10 years, and those were all G80s. RMS for me.

Mr G said:

When deciding to stock up on composite single use F & G motors what proportion do you choose between low, medium and high delay times? Obviously, it depends on the rocket. Just curious if there is a preponderance of one over the other.

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If you are really "just stocking up" then I would suggest not choosing - just get a few motors in each of the delay times.

But I don't think that's really how most of us do our motor shopping.

The delay you buy is really dependent upon the rocket you fly.

I use an F42-4 in my Wildman Jart. My Aerotech Mustang needs an F42-8 because it's lighter than the Jart.

So how do you know which motor to buy?

You can SIMULATE your rocket to see how it fly's by using a simulator like OpenRocket. It does take a little time to make sure the simulation is accurate, and some trial-and-error with the delays.

Another REALLY EASY method is to use online resources. Most kits have recommended motors you can look up on the manufactures website. Also try looking at the flight logs at www.rocketreviews.com. Then there is www.apogeerockets.com - find the rocket kit listed, and look at the recommended motors.

Have Fun!

-7 is what probably the most rockets are made for, especially large MPRs such as the PSII builder kits. If you like stuffing big motors in smaller rockets, 10, for low and slow maybe 4. Delay times were a big factor towards going with RMS because I kept wanting 5.5 on motors avail. in 4's and 7's. Often with reduced ejection charge and always with easier-to-light scraped grains.

Mr G said:

Sorry, I wasn't clear. I was referring to the old style SU non-adjustable delay types. Thanks for the responses so far.

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Since the older type SU motors probably aren't available anymore, your question is moot. Enjoy the new SU, known as DMS and use the delay adjustment tool.

hball55 said:

Since the older type SU motors probably aren't available anymore, your question is moot. Enjoy the new SU, known as DMS and use the delay adjustment tool.

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What are you talking about?

Regular non-adjustable delay time single use Aerotech motors still exist, are still manufactured, and are not replaced by a DMS version.

shreadvector said:

What are you talking about?

Regular non-adjustable delay time single use Aerotech motors still exist, are still manufactured, and are not replaced by a DMS version.

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I think that's unfortunate, but they probably don't want normal users to have to add the BP themselves.

Sometimes the simulations reveal some enexpected results. I wanted to try all four of the different formulations of the Econojet F motors in my Leviathan. The F20, F23, and F27 all wanted 4-second delays according to OpenRocket. But the F42 wanted the 8-second delay, apparently. It seemed odd to me, but I double-checked everything. The deployment speed was going to be very high on the 4-second delay, so I bought the 8. I've flown the other 3 motors, and they all worked great with 4-second delays. Still haven't tried the F42-8 yet. It just seems long. I'm bringing the rocket and those motors to Snow Ranch tomorrow (technically today). I think I might get a second opinion before flying that motor with the 8-second delay.

^^-- I'm coming up with 6 sec. or less on the F42. Sometimes there's motors you just can't fly due to such reasons (in my case, I had rockets there was only one SU G that would work, of all of them).

There is only one DMS motor so far in the F-G range. Also there are no non-HP reloads avail in only a single long delay, like most HP motors are going. I find it unlikely that will happen, because some flyers in this range are too beginner. Also, the drill tool costs more than some of these motors (if you have to pay for it).

bill_s said:

^^-- I'm coming up with 6 sec. or less on the F42. Sometimes there's motors you just can't fly due to such reasons (in my case, I had rockets there was only one SU G that would work, of all of them).

There is only one DMS motor so far in the F-G range. Also there are no non-HP reloads avail in only a single long delay, like most HP motors are going. I find it unlikely that will happen, because some flyers in this range are too beginner. Also, the drill tool costs more than some of these motors (if you have to pay for it).

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Thanks, Bill. That's sort of what I expected. The simulated deployment speed was kind of fast on both 4 seconds and 8 seconds, but not quite as fast on 8. It seems like a 4-second spread between the two is a pretty big jump and they should make a 6 second delay too. After buying the Econojets in 8-second delays, the Fry's sale happened, and I got several of the SU F50-6T's, so I can try the Blue Thunder propellant on those. The Econojets were a fun way to try a variaety of propellant types. I really enjoyed the White Lightning, Redline and Blackmax, and I have a feeling Blue Thunder is likely to be my least favorite (but still cool in it's way).

Thanks again for confirming my suspicions about the F42-8.