chute arrangement for dual deploy using a h550 or j270 motor

[Lt72884]

I am looking over this PDF i found online and here is a snippet of what it shows to do for chute order:

Since i personally have not done a dual deployment yet, i am going to test it out on a new loc-iv kit i got. I am making the switch band and sled this week.

In my mind, i see the nose cone getting popped off first from electronics, then motor ejection OR electronics pop off the upper section of the rocket (the section that had the nose cone on it) and the main chute comes out. I see it this way in case electronics fail, at elast, hopefully, the motor ejection will deploy the main chute.

Or am i visualizing what and how things are done?

In the image above, the motor ejection (backup) would deploy the drogue if electronics fail, is that correct? Also, can a rocket land on a drogue at least somewhat safely?

thanks

I have had to take a break from rockets for about 8 months while i focus on graduating school and i had no money : )

 

[Voyager1]

Dual deployment typically employs an altimeter to deploy a drogue at or near apogee, with the possibility of also using motor ejection as a delayed drogue backup. The separation is typically between the aft end of the avbay and the booster section of the rocket. The altimeter then deploys the main at a predetermined altitude on descending by separating either at the nosecone, or from the forward end of the avbay and the upper section including the nosecone.

Do some more research. Here is a good place to start https://www.apogeerockets.com/Intro-to-Dual-Deployment

Landing on a drogue only can succeed, but it will depend upon the descent velocity (which might be 2-3+ times the velocity under the main) and rocket construction. It’s not something you want to rely on without damage.

 

[3stoogesrocketry]

I am looking over this PDF i found online and here is a snippet of what it shows to do for chute order:

Since i personally have not done a dual deployment yet, i am going to test it out on a new loc-iv kit i got. I am making the switch band and sled this week.

In my mind, i see the nose cone getting popped off first from electronics, then motor ejection OR electronics pop off the upper section of the rocket (the section that had the nose cone on it) and the main chute comes out. I see it this way in case electronics fail, at elast, hopefully, the motor ejection will deploy the main chute.

Or am i visualizing what and how things are done?

In the image above, the motor ejection would deploy the drogue, so no chance of motor backup? is that correct? Also, can a rocket land on a drogue at least somewhat safely?

thanks

I have had to take a break from rockets for about 8 months while i focus on graduating school and i had no money : )

180 degrees off. The picture you posted shows the correct orientation. Split the rocket in half first with the small parachute, then the nose pops off with your main parachute.

 

[David Schwantz]

Landing with drogue only is way better than ballistic.

 

[Lt72884]

Landing with drogue only is way better than ballistic.

that is for sure true. I agree with that. I have seen 2 or 3 come in ballistic and it was scary. landed in the area of the cars

 

[Lt72884]

Dual deployment typically employs an altimeter to deploy a drogue at or near apogee, with the possibility of also using motor ejection as a delayed drogue backup. The separation is typically between the aft end of the avbay and the booster section of the rocket. The altimeter then deploys the main at a predetermined altitude on descending by separating either at the nosecone, or from the forward end of the avbay and the upper section including the nosecone.

Do some more research. Here is a good place to start https://www.apogeerockets.com/Intro-to-Dual-Deployment

Landing on a drogue only can succeed, but it will depend upon the descent velocity (which might be 2-3+ times the velocity under the main) and rocket construction. It’s not something you want to rely on without damage.

the pictures i posted came from that article from their conversion kit : ) Just wondering if the images were indeed correct. I have seen a mix of setups

I do currently have all the electronics. I have about 4 eggtimers i have put together as well as a missile works altimeter. Those eggtimers are interesting to put together.

From what i gather, i should not depend on the motor ejection to blow the drogue, only use motor ejection as backup, if i remember correctly from when i started this a while back??

Landing on drogue would only be if electronics failed and the motor ejected only the drogue chute, which is much better than a ballistic rocket, which i have seen and that is scary.

I just was not sure of the correct order of the chute. I saw a post on here during my research that had it with main in the booster and drogue in the cone.

My concern is weight and getting things tangled. Booster section is the heaviest, so when its falling with the drogue, and then the nose pops off with the main, all of a sudden the nose cone would be "heaviest" due to more drag, so the booster falls bellow, could this not cause entanglement?

thanks for the reply and information.

 

[Lt72884]

180 degrees off. The picture you posted shows the correct orientation. Split the rocket in half first with the small parachute, then the nose pops off with your main parachute.

ok, great. thank you. When i hear motor back, i keep thinking thats for the MAIN chute in case electronics fail, but i have it backwards haha.

 

[3stoogesrocketry]

the pictures i posted came from that article from their conversion kit : ) Just wondering if the images were indeed correct. I have seen a mix of setups

I do currently have all the electronics. I have about 4 eggtimers i have put together as well as a missile works altimeter. Those eggtimers are interesting to put together.

From what i gather, i should not depend on the motor ejection to blow the drogue, only use motor ejection as backup, if i remember correctly from when i started this a while back??

Landing on drogue would only be if electronics failed and the motor ejected only the drogue chute, which is much better than a ballistic rocket, which i have seen and that is scary.

I just was not sure of the correct order of the chute. I saw a post on here during my research that had it with main in the booster and drogue in the cone.

My concern is weight and getting things tangled. Booster section is the heaviest, so when its falling with the drogue, and then the nose pops off with the main, all of a sudden the nose cone would be "heaviest" due to more drag, so the booster falls bellow, could this not cause entanglement?

thanks for the reply and information.

Attach your drouge 1/4 of your shock cord distance away from the payload bay. Meaning if you have a 40 foot shock cord, your drouge should be no farther back the 10 feet away from your payload Bay. This will allow the booster to fall below the main chute.

 

[3stoogesrocketry]

 

[Lt72884]

Thats awesome way of doing it with a separate chute for the nose cone.

Thanks for this video.

I think im going to get a longer cord to help prevent a tangled mess

 

[Lt72884]

Attach your drouge 1/4 of your shock cord distance away from the payload bay. Meaning if you have a 40 foot shock cord, your drouge should be no farther back the 10 feet away from your payload Bay. This will allow the booster to fall below the main chute.

Sounds great. I have a 15 foot cord that came with the kit that i used for my lvl 1 and lvl 2 flights.

I was just going over some figures and made the decision that in order to keep things from getting tangled, i will need a much longer cord.

Thanks for the information. I will start with a 40 foot cord, maybe even 30 feet since this is a much smaller rocket.

 

[Lt72884]

Thank you all for the information. Dual deployment is new but not haha.

I have all the electronics, and understand how it all works except for chute placement. I saw alot of mixed setups, and one called MED or HED... Cant remember the first letter.

I did work with a small group a year or so ago on a 10 foot rocket, but i didnt get to build any of it so i missed out.

This is why i am now doing it on my own starting with my LOC IV that i have.

I have also built my own airframes from either rolling butcher paper into tubes or using shipping tubes from print stores, and even using tubes from window tinting stores.

 

[Voyager1]

I have all the electronics, and understand how it all works except for chute placement. I saw alot of mixed setups, and one called MED or HED... Cant remember the first letter.

HED: Head End Deployment

 

[Lt72884]

HED: Head End Deployment

thank you. I will go look this up. Once i get the hang of dual deployment, ground testing etc, ill start trying out other things.

 

[3stoogesrocketry]

Thank you all for the information. Dual deployment is new but not haha.

I have all the electronics, and understand how it all works except for chute placement. I saw alot of mixed setups, and one called MED or HED... Cant remember the first letter.

I did work with a small group a year or so ago on a 10 foot rocket, but i didnt get to build any of it so i missed out.

This is why i am now doing it on my own starting with my LOC IV that i have.

I have also built my own airframes from either rolling butcher paper into tubes or using shipping tubes from print stores, and even using tubes from window tinting stores.

No problem. If I can also make a suggestion, once you are done and get ready to fly, if possible, fly it main at apogee like a normal rocket. Use a smaller motor like a H283 SU and use your altimeter with a drogue charge only to pop the main parachute. Fly it to 600/800 feet so you can watch the entire flight up close. Fly it with motor ejection as if it was the primary deployment method. Us a BP "backup" charge and run your main using only a e-match no black powder. This will verify you're doing everything correct before you send it hard and don't have it right.

thank you. I will go look this up. Once i get the hang of dual deployment, ground testing etc, ill start trying out other things.

This method is almost only for fiberglass kits.

 

[Lt72884]

No problem. If I can also make a suggestion, once you are done and get ready to fly, if possible, fly it main at apogee like a normal rocket. Use a smaller motor like a H283 SU and use your altimeter with a drogue charge only to pop the main parachute. Fly it to 600/800 feet so you can watch the entire flight up close. Fly it with motor ejection as if it was the primary deployment method. Us a BP "backup" charge and run your main using only a e-match no black powder. This will verify you're doing everything correct before you send it hard and don't have it right.



This method is almost only for fiberglass kits.

i was thinking something similar to at least get it down before testing it fully on dual deploy. I was thinking of using the altimeter, like you say, to pop the main chute without using any blackpowder in the motor. But what if the electronics do not fire, my rocket will come in ballistic.

IU could use the altimeter and fire a drogue charge for the main, and if electronics fail, at least the motors blackpowder ejection will fire and be my back up

 

[3stoogesrocketry]

i was thinking something similar to at least get it down before testing it fully on dual deploy. I was thinking of using the altimeter, like you say, to pop the main chute without using any blackpowder in the motor. But what if the electronics do not fire, my rocket will come in ballistic.

IU could use the altimeter and fire a drogue charge for the main, and if electronics fail, at least the motors blackpowder ejection will fire and be my back up

Your misunderstood me in the first paragraph, but I was saying the exact same time you said in your second paragraph. You got this . Don't over think it

 

[Lt72884]

Your misunderstood me in the first paragraph, but I was saying the exact same time you said in your second paragraph. You got this . Don't over think it

perfect. Yeah, i misunderstood, but then i figured it out in my second paragraph.

thanks for all the information. This week ill either laser cut all my parts or 3d print my sled. Or just use my scroll and band saw and make it super simple. Doesnt need to be complicated haha.

 

[Lt72884]

ohhh, i forgot to ask, do i need shear pins for such a small rocket like the LOC-IV? I dont use them at all for single deployment, but what about double?

 

[David_Stack]

ohhh, i forgot to ask, do i need shear pins for such a small rocket like the LOC-IV? I dont use them at all for single deployment, but what about double?

Discussed ad nauseum here on the forum.

Ran a search and came up with pages and pages of discussion: https://www.rocketryforum.com/search/584352/?q=shear+pins&o=relevance

 

[Aeva]

ohhh, i forgot to ask, do i need shear pins for such a small rocket like the LOC-IV? I dont use them at all for single deployment, but what about double?

Depends on the diameter and if there is weight in the nosecone. The easiest way to tell if you need them is to abruptly tug as hard as you can (throw it forward for some momentum before you tug) on the drogue's cord while the main's nosecone is still in the body tube with the parachute. This simulates the drogue's ejection charge/the engine ejection charge. If the nosecone comes out, you probably could use shear pins. If you have a cardboard/paper tube, try just taping the shoulder of the nosecone until its snug in the body tube instead because shear pins might shear your tube if it's not a stronger material.

Another thing you can try instead of shear pins is braiding the main chute's cord so it requires the full ejection charge force to come undone. The braid should come undone as the cord is stretched to length. I haven't done this successfully before so ymmv.

e: to be clear, I mean the shock cord, NOT the parachute cord.

 

[Titan II]

ohhh, i forgot to ask, do i need shear pins for such a small rocket like the LOC-IV? I dont use them at all for single deployment, but what about double?

Regardless of size or material, I use them in all HP rockets at all separation points.

 

[Aeva]

Regardless of size or material, I use them in all HP rockets at all separation points.

Is that just how you like to do it? or is there a reason, like to counter the build up of static pressure inside the body tube during ascent?

 

[Titan II]

Is that just how you like to do it? or is there a reason, like to counter the build up of static pressure inside the body tube during ascent?

It does not have anything to do with pressure. But there is as reason: consistancy.

 

[Aeva]

It does not have anything to do with pressure. But there is as reason: consistancy.

Fair. I'm still inexperienced with shear pins and was wondering if there was a necessity to it. I'm only using them for the main at the moment. I might use em on both sections with some rockets because I'm experimenting with servo powered roll control. But for something like my EZI where it payload tube doesn't have any rotational forces from fins, I think I'll just keep it on the main chute. My thought is fewer prep steps, fewer things to forget before launch.

 

[Titan II]

My thought is fewer prep steps, fewer things to forget before launch.

My other quirk. All rockets are ready to fly (except igniter, but they are taped to the rocket) before they even go into the truck.

 

[Aeva]

My other quirk. All rockets are ready to fly (except igniter) before they even go into the truck.

Yeah that seems like the way to go. I originally would just prep at the field, but wind and stuff like that makes it a PITA. Going forward, definitely gonna follow your lead with that.

 

[Lt72884]

My other quirk. All rockets are ready to fly (except igniter, but they are taped to the rocket) before they even go into the truck.

This is what I do too because of how many limited launches we have and how many people show up, I just want to be ready to go within 20 seconds. I've done this for all my level one and two flights. Which is about four or five total

 

[Titan II]

Something to think about. I do not use a checklist, but masking tape is my friend. Everything I need to do is annotated on masking tape, and taped to the rocket near the item to which it refers. For example, "turn on alt #1" is taped next to the switch hole or the leads sticking out (twist and tape). This goes on for all components and the tape is removed after I complete each task. When there are no more masking tape notes, it is ready to fly.

 

[Lt72884]

Regardless of size or material, I use them in all HP rockets at all separation points.

Sounds good thank you. I was thinking of 3D printing some, but I'm not sure how inconsistent that would be. I 2as also thinking of using just pure filament, but sometimes filament is to flexible and doesn't break or shear it just bends. One idea I had just for the heck of it and for testing because it's fun, is to heat the filament up to its melting point and then rapidly cool it to make it more brittle. But that would be for just purely testing and for fun.