Single deployment with a K and L engine

[Nilo]

Members:

I want to fly my newly build fiberglass rocket with DMS engines with time delays. I know that double deployment is recommended for L and above, but I rather use single deployment, along with a Chute release.

Comments?

Right now I don’t intend to get Level 3 certified, so I want to fly the highest engine within my certification ( Level 2).

 

[les]

Depends on many factors, so at least I can't answer.
How big is your rocket?
How heavy is the rocket?
How big is your field?
What are typical wind conditions?

Will you have a tracker?
Do you want to get the rocket back?

 

[Steve Shannon]

Electronically controlled deployment is required for all flights that are L and above. Doesn't have to be dual deployment, but must be electronically controlled. That's in NFPA 1127 and NFPA 1125 and I suspect you can no longer buy an L motor with a charge well.

 

[jmasterj]

Doesn't the L1000 have a delay?

 

[Steve Shannon]

Even if it does it's not permitted by NAR or Tripoli Safety Codes.

 

[3stoogesrocketry]

Using a chute release negates having single deploy . If your question is can I duel deploy on a single break airframe using a L motor ejection charge at apogee and a chute release around 500ish , buy TRA codes of conduct , no , you cannot.

 

[Steve Shannon]

Even if it does it's not permitted by NAR or Tripoli Safety Codes.

I suppose you could use it for a backup charge, but all rockets above 2560 Ns are required to fly with electronic deployment.

 

[Nilo]

Depends on many factors, so at least I can't answer.
How big is your rocket?
How heavy is the rocket?
How big is your field?
What are typical wind conditions?

Will you have a tracker?
Do you want to get the rocket back?

Rocket- Wildman Shape Shifter 3”
Tracker- Eggtimer tracking system
Field- Big enough for up to N engines

 

[Nilo]

Electronically controlled deployment is required for all flights that are L and above. Doesn't have to be dual deployment, but must be electronically controlled. That's in NFPA 1127 and NFPA 1125 and I suspect you can no longer buy an L motor with a charge well.

 

[Nilo]

If you have an L engine with time delay, how do you “electronically” deploy ?

 

[Nilo]

Using a chute release negates having single deploy . If your question is can I duel deploy on a single break airframe using a L motor ejection charge at apogee and a chute release around 500ish , buy TRA codes of conduct , no , you cannot.

Doesn't the L1000 have a delay?

Yes

 

[3stoogesrocketry]

Yes

Back in the day the first M1939 I flew had motor ejection.
You electronically deploy the parachutes using altimeters / accelerometers / timers / RC activation .... There are several methods.

 

[heada]

Aerotech posted yesterday in anothwr thread that anything above a K motor, the delay is not accurate.

Electronic deployment is highly recommended if you want to recover the rocket.

https://www.rocketryforum.com/threa...n-commercial-apcp-motors.172341/#post-2270468

 

[Nilo]

Back in the day the first M1939 I flew had motor ejection.
You electronically deploy the parachutes using altimeters / accelerometers / timers / RC activation .... There are several methods.

I think using a Chute Release counts as an electronically device to deploy the parachute, just like you described but now is with a Chute Release.

 

[Steve Shannon]

I think using a Chute Release counts as an electronically device to deploy the parachute, just like you described but now is with a Chute Release.

No, it definitely doesn’t.

I apologize. I didn’t intend that to be so curt.
There’s a concept of primary recovery event which must occur. Something must happen to ruin the stability of the rocket so it won’t fall like a lawn dart. Typically that requires that the nosecone be ejected at the very least. The JLCR is a secondary event. It relies on a prior event, which is the primary event.

 

[crossfire]

Aerotech posted yesterday in anothwr thread that anything above a K motor, the delay is not accurate.

Electronic deployment is highly recommended if you want to recover the rocket.

https://www.rocketryforum.com/threa...n-commercial-apcp-motors.172341/#post-2270468

They have to be accurate wouldn't they have been certified that way?

 

[heada]

They have to be accurate wouldn't they have been certified that way?

Sometimes a delay grain is included as tracking smoke and not intended to be used for ejection.

 

[jmasterj]

I think using a Chute Release counts as an electronically device to deploy the parachute, just like you described but now is with a Chute Release.

Negative.

 

[UPscaler]

Some L1000s are plugged, and some are not. Often you'll see they're still listed with an 18-second delay, but when you get one, it's plugged.

I've flown a few motor deploy Ks, though. Last year, I did a K850 with motor deploy in my 7.5" LOC Iris and a K740 C-Star with motor deploy in my 4" Big Daddy.

However, if you really want to fly the biggest motors you're currently certified for you're going to have to go to electronics, as all 75mm loads are plugged. Dual Deploy can seem intimidating at first, but it's not bad once you actually get into it. Plus with altimeters like the RRC2+ around, you can get into electronic deployment for less than half of the cost of a chute release.

Braden

 

[cerving]

If you have an L engine with time delay, how do you “electronically” deploy ?

Leave out the BP, and use it for your electronic deployment. FYI, Eggtimer sells an apogee-only altimeter, the Eggtimer Apogee, that you can mount in your nose cone and use along with your Chute Release. That satisfies the Tripoli requirement for L motors... at it's only $15.

 

[user 30299]

Some delays are no more than 14 seconds. So what if apogee is at 18 seconds? Wouldn't you be popping the chute while you're still coasting upward?

 

[3stoogesrocketry]

I think using a Chute Release counts as an electronically device to deploy the parachute, just like you described but now is with a Chute Release.

No it does not deploy a parachute . It releases it from a rubber banded folded up chute . If the motor does not deploy , your rocket will be a ballist return . A electronic deployment uses either BP or compressed gasses to physically break the rocket in two and slow the decent. I would suggest a simple RRC3 altimeter. They are under 50 dollars. You an use it to simply deploy at apogee , then let your chute deploy do it's thing.

 

[roytyson]

Steve, could you link the doc that spells the L and above document.

 

[rfjustin]

Members:

I want to fly my newly build fiberglass rocket with DMS engines with time delays. I know that double deployment is recommended for L and above, but I rather use single deployment, along with a Chute release.

Comments?

Right now I don’t intend to get Level 3 certified, so I want to fly the highest engine within my certification ( Level 2).

Buy a Missile Works RRC3, read the manual, learn how to use it, problem solved. Got to take the electronic deployment plunge at some point...

 

[Steve Shannon]

Steve, could you link the doc that spells the L and above document.

It’s NFPA 1127 paragraph 4.10.2. It’s free (but painful) to read at NFPA.org, requiring a free login.
And unfortunately the security settings on the pdf don’t allow copying and pasting.

But we include it in our Safe Launch Practices document:
12. Rockets with more than 2560 N-s of total impulse must use electronically actuated recovery mechanisms.

 

[ThirstyBarbarian]

Just to clarify terms. “Dual deploy” refers to having two (dual) deployment events. And “electronic deployment” refers to using electronics, such as an electronic altimeter, to activate the deployment. People get those two mixed up, but they aren’t the same. “Motor eject” refers to using the motor’s delay grain to ignite the ejection charge after a set amount of time.

You can put together a form of dual deployment thst uses motor eject and chute release and does not use electronic deployment. I think that is what you are hoping to do. You can’t do that with an L motor, according to the rules. You can do it with a K, but it might not be a great idea.

For an L, you need to use an altimeter to pop the nosecone off. At that point you could just set it up to have the main come out. Or you could set it up to fall drogueless and deploy the main with a chute release. Or you could set it up to use a drogue and deploy the main with a chute release. Several options.

Or you could put together a traditional dual deploy setup with an altimeter firing both the initial ejection charge and the second charge to deploy the main. It sounds like you don’t want to do that.

 

[AlexBruccoleri]

It’s NFPA 1127 paragraph 4.10.2. It’s free (but painful) to read at NFPA.org, requiring a free login.
And unfortunately the security settings on the pdf don’t allow copying and pasting.

But we include it in our Safe Launch Practices document:
12. Rockets with more than 2560 N-s of total impulse must use electronically actuated recovery mechanisms.

Is it possible or worth asking for the NFPA to allow direct links to the most up-to-date NFPA codes on the Tripoli/NAR websites. I find it weird that those codes are hard to access.

 

[Antares JS]

I think using a Chute Release counts as an electronically device to deploy the parachute, just like you described but now is with a Chute Release.

I feel like some of these other responses aren't as clear as they could be, so I'll take a stab at it...

The chute release does not get your parachute out of the rocket. It only releases a parachute that has already been ejected from the rocket. To eject the parachute from the rocket is what requires either motor ejection or electronic ejection. With L motors and above, motor ejection is not an option, except, apparently, for the Aerotech L1000, which as far as I can tell, has the usual adjustable delay included with a DMS motor. Whether it should have that or not, I'm not going to get into as I'm not knowledgeable about the finer points of the NFPA guidelines.

Electronic deployment is accomplished with a device, usually referred to as an altimeter, equipped with a barometric pressure sensor that is able to detect when a rocket reaches apogee and is heading back down. When it senses apogee, it will activate an electric match wired to it, and that electric match sets off a BP ejection charge that performs the same way as a motor-activated ejection charge. If the rocket is using dual deployment, the altimeter will sense when the rocket has dropped to a certain altitude after reach apogee and activate a second electric match and ejection charge at that point.

 

[Walter Longburn]

An 18 second delay is not enough for a minimum diameter rocket on an L1000. If the rocket isn't minimum diameter you can often use the L1000 ejection charge as a backup.

 

[rharshberger]

Also according to a post made yesterday by Aerotech in another thread, delays become less accurate at higher altitudes in larger rocket motors hence the reason we don't have motor delays in 75mm and larger motors, the same is probably true for the L1000W.