Long Delays

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blackbrandt

That Darn College Student
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So I was simming a 29 mm rocket to fly on the H410. The coast time is 17 seconds, but the max delay on the H410 is 14 seconds. Is there a way to lengthen the delay?
There is no way you will convince me to put an altimeter in there.
Thoughts?
Matt
 
In that case, either add weight to the rocket or deploy early (REALLY early)
 
The simulated delay is an approximation based on the data you entered. So, it's possible that the 14 second delay will be fine.

I prefer using an altimeter to deploy the recovery system. You don't have to worry about calculating an aapropriate delay and, if the flight deviates from your predictions, the 'chute will still deploy at the right time.

For example, I launched a rocket that was predicted to go abut 4000 feet on it's I motor. For some reason, it took a sharp right turn and basically stopped at about 400 feet just after the motor burned out. The altimeter sensed that apogee had been reached and the 'chute deployed.

-- Roger
 
1) Use a LOT of epoxy
2) 15 coats of paint (with a brush)
3) do not airfoil the fins-1/2" plywood flies just fine without it
4) use steel pipe for a launch lug
5) Hardwood nose cones look good with a natural stain
6) chain instead of kevlar-packs a little funky, but usually deploys when the rocket turns over
I may have forgotten a few tricks, but this should suck as much performance outta the bird as possible...you may have to drill for a 4 sec delay.
 
1) Use a LOT of epoxy
2) 15 coats of paint (with a brush)
3) do not airfoil the fins-1/2" plywood flies just fine without it
4) use steel pipe for a launch lug
5) Hardwood nose cones look good with a natural stain
6) chain instead of kevlar-packs a little funky, but usually deploys when the rocket turns over
I may have forgotten a few tricks, but this should suck as much performance outta the bird as possible...you may have to drill for a 4 sec delay.

No need for the extra tricks...I simmed a model with the ones you listed and it comes out JUST RIGHT ;-)
 
Basically, no.

If you get a Telemini it will add almost no weight, dual-deployment, and radio tracking capabilities (so you won't lose it), but someone you know would have to be Ham licenced to use it.
 
The best way to get "more delay":

Start with any AT reload. Be very careful with your sims and your build. Work out all the details of mass/drag/thrust/atmospherics/etc. Tweak all the parameters until you get everything worked out perfectly. On launch day be meticulous with your pre-launch prep, and pay careful attention to conditions - adjust if necessary.

Then, and this is a very important step, adjust your mindset such that you are REALLY counting on that delay time being just right. KNOW that it is absolutely critical for a successful flight. The more focus you put on this step, the greater chance that this method will work.

Now launch that rocket. You will find, more often than not it seems, that your delay time will be at least a few seconds longer than you had planned/simmed/adjusted/build for. Although those few seconds may feel like minutes at time. Very exciting.

Note: on some occasions, this whole process will provide the opposite results - i.e. your actual delay time will be much SHORTER than you planned. This uncertainty adds another measure of excitement.






Or you could fly an altimeter.

s6
 
1) Use a LOT of epoxy
2) 15 coats of paint (with a brush)
3) do not airfoil the fins-1/2" plywood flies just fine without it
4) use steel pipe for a launch lug
5) Hardwood nose cones look good with a natural stain
6) chain instead of kevlar-packs a little funky, but usually deploys when the rocket turns over
I may have forgotten a few tricks, but this should suck as much performance outta the bird as possible...you may have to drill for a 4 sec delay.

Coffee on my keyboard and in my schnoz.....hope you`re happy !


Paul T
 
I usually just put some Dow 111 on the aft face of the delay grain, this should give you a pretty much unlimited delay... No special drilling tool needed...
 
mdoering said:
I usually just put some Dow 111 on the aft face of the delay grain, this should give you a pretty much unlimited delay... No special drilling tool needed...

It works if you paint it on the front of the delay too - it's very reliable that way ;)
 
Was mine the only serious response to this thread?

Honestly, bb, I wanted to do the same project and concluded that without making performance suboptimal, the only means for doing this is with a Telemini. That takes care of both deployment and tracking. The only problem is that you have to make it long enough for the wire.

Maybe I will do it i1299 size...
 
CarVac and BB. I was gonna suggest this motor in 54mm airframe...and still suggest streamers.
Not the huge 4 or 5" mylar flappers, but something thinner so you get it back without a GPS transmitter.

Ahh Streamers...a Lost Art....:wink:
 
I don't think Matt trusts me anymore.....
Nope, I don't... :p
Yes, next time your at a launch,stop by your vendor & purchase some delay stretcher. Paint some on the delay to slow it down.
That should do the trick!
Is there really such a thing?
I usually just put some Dow 111 on the aft face of the delay grain, this should give you a pretty much unlimited delay... No special drilling tool needed...
Umm, except for the fact that I want the rocket to be recovered.
It works if you paint it on the front of the delay too - it's very reliable that way ;)
Wow... Can I get a video of this? :)

Was mine the only serious response to this thread?
Yes.
Honestly, bb, I wanted to do the same project and concluded that without making performance suboptimal, the only means for doing this is with a Telemini. That takes care of both deployment and tracking. The only problem is that you have to make it long enough for the wire.

Maybe I will do it i1299 size...
There is no way I am putting electronics in a rocket that I am probably never going to see again. To give you an idea of recovery and tracking, can you see a beer bottle a mile away? Neither can I. (Before those comments start, the bottle of beer is empty.)


CarVac and BB. I was gonna suggest this motor in 54mm airframe...and still suggest streamers.
Not the huge 4 or 5" mylar flappers, but something thinner so you get it back without a GPS transmitter.

Ahh Streamers...a Lost Art....:wink:

Yes, this recovers on a streamer.








The whole purpose of this rocket is to teleport off the pad. And fyrwrxz, ummm, the only thing I have to say is, um, uhhh, "WOW." (Not really.)
 
There is no way I am putting electronics in a rocket that I am probably never going to see again. To give you an idea of recovery and tracking, can you see a beer bottle a mile away? Neither can I.

If you'll probably never see the rocket again, why worry about the delay? Or go with an inexpensive deployment controller. You'll be paying a lot more for the motor and case that you'll probably never see again, so what's another $29?
 
Here's a serious reply: use pyrotechnic fuse at the top of the delay and move your charge to the end of the fuse. The ubiquitous cannon fuse is theoretically useful, and burns about 2.5 seconds per inch. If you can find an actual pyrotechnic supplier, look for timing fuse. It burns reliably - this stuff: https://www.cannonfuse.com/store/pc/Premium-Time-Fuse-1-4-p491.htm is rated at 2 seconds per inch. Remember that this stuff is lit from a lift charge (2FA powder in the mortar) and ignites a burst charge at very close to apogee with exceptionally high reliability. Very, very few shells do not burst once fired. Once stabilized laterally, it's very resistant to shock - even an H410 can't hold a candle to a bag of 2FA in a mortar that has a 3-4' total "thrust" distance and an apogee of 600 feet on a 2lb projectile

If you do this, I would consider packing the fuse in a tube to match the diameter of the top of the delay grain and filling the tube with epoxy or clay to stabilize it and give you a good way to attach the fuse to the delay grain and provide a "pocket" for your ejection charge (use a 2.5" tube length with 1.5" of fuse and a 1/2" recess at each end). At 10' for about $15 shipped, that linked fuse above will last you until you lose interest in pissing away 3G casings on 6 oz rockets! ;-)

Note: good practice for shells involves "cross matching" the ends of timing fuse with thermalite (though it appears that it may be hard/impossible for amateurs to get these days), however for your application it should not be necessary as you have a much better ignition source and sink than in a firework shell.
 
You realize, a Telemini is a radio tracker as well as an altimeter, ensuring that you can find it (as well as the motor case) afterwards. That is why I said that it is the only real option other than letting it eject early. I have thoroughly considered this problem before.

Or that firework fuse, assuming you can get it to light from the delay grain reliably.
 
I would like to say, but cannot say, that you switch delay grains. Find a motor with a 17 second delay and switch delay grains. Just label your unused motor that it has a 14 second delay grain so that you do not get confused. Of course I do not believe you can ethically do this and still follow the guidelines. Although I know you can shorten the delay, I am uncertain that you can lengthen the delay, and do it in this manner. I would welcome a correction to my mis-perceptions, if there are any.
 
If you switch, aside from possibly making it EX, remember that the delay time starts from the end of the burn, but the delay starts burning at ignition. (i.e.: your delay grain is actually a (thrust time + delay) length).
 
If you switch, aside from possibly making it EX, remember that the delay time starts from the end of the burn, but the delay starts burning at ignition. (i.e.: your delay grain is actually a (thrust time + delay) length).

Yes. The "17 second" delay element from one motor is likely to be the same delay element as the "14 second" one in another motor. The delay starts burning when the motor ignites and may burn at a different rate in different motors. So, the same delay element in two different motors will provide a different delay time.

-- Roger
 
If he's that opposed to electronics, I suppose a spool of thread would work as an analog tracker... (provided the motor doesn't burn through it on the ascent...) then he could just follow the thread right to it... :rofl:
 
Here's a serious reply: use pyrotechnic fuse at the top of the delay and move your charge to the end of the fuse. The ubiquitous cannon fuse is theoretically useful, and burns about 2.5 seconds per inch.

From The Producers (1968)
Franz Liebkind: Gentlemen. Ve have here a technical problem. Hmm? I do not know if vat ve have here is ze quick burning fuse or ze slow buring fuse. Ja, ja, I must find zis out.
[snips dynamite fuse]
Franz Liebkind: Zis is critical.
[lights fuse with match]
Franz Liebkind: Ha ha ha, ja ja, you see zis? You see zis here vat I have told you? Yeah, zis is an example of smartness here. I have said that zis is ze quick fuse. Huh? And zis IS ze quick fuse.
[pause]
All: THE QUICK FUSE!
[explosion]
 
So what y'all are saying is launch it at an EX launch?

Why? changing the delay does not change the motor burn, impulse, nozzle, or case.

i asked this question to a BOD member who's reply was that, in his opinion it does not change the motor. your just changing the delay.

you do this same delay change in AT motors for short med and long delay grains.

it is ultimately up to your Prefect / LD or RSO if they will alllow it.
 
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