Ejection testing questions


Daniel Greuel
 

I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Jonathan Sivier
 

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan


On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Mark Joseph
 

Hi Dan,

Don't apologize for the questions, please - all good stuff. Some comments and questions follow.

Still a pretty "enthusiastic" charge. And especially so with that length shock cord, which could easily stand to be twice that long. Ultimately, getting the chute all the way out of the airframe, so that it's fully exposed for easy opening, is the goal. Hitting the end of the shock cord length with a big jerk, and pulling the airframe along, is usually a sign that you've got too much.

Are you, in fact, separating at two different points - drogue compartment below, and main above?

Do you intend to use shear pins of some sort to hold parts together prior to deployment, or is this just friction-fit? Generally speaking, shear pinning is a good idea, at least for the section containing the Main parachute, to prevent it from prematurely opening when the drogue section shock cord fully extends (with a jerk).

For some of us, it helps to work backwards from the force required to separate the parts, which is derived from the number of shear pins used.

You can, if you want, run the charge down to the bottom of the airframe. That's a matter of personal preference.

I'm sure you'll hear from several of us on these points, and there are lots of ways to do it right. We can point you some more resources, too.

Mark

________________________________________

From: cia-rocketry@groups.io <cia-rocketry@groups.io> on behalf of Daniel Greuel <kc9thp@...>
Sent: Monday, April 13, 2020 3:02 PM
To: cia-rocketry@groups.io
Subject: [cia-rocketry] Ejection testing questions

I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Daniel Greuel
 

No shear pins. It’s friction fit. I plan to use tape instead of shear pins on the nose cone only. I had one calculator that said .3 grams. I was worried about getting consistent ignition with a charge that’d small  I’ll try .5grams in a bit

 Rocket is around 40” tall so Kevlar is 3.6x the rocket length


On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@...> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Jonathan Sivier
 

The problem you can run into with friction fit (ask me how I know ;-) ) is that it can vary with the temperature and humidity, especially when you use tape. Also as the rocket it flown dirt and grime can build up on the moving parts and change to force needed to open them up.

Jonathan


On 4/13/2020 3:37 PM, Daniel Greuel wrote:
No shear pins. It’s friction fit. I plan to use tape instead of shear pins on the nose cone only. I had one calculator that said .3 grams. I was worried about getting consistent ignition with a charge that’d small  I’ll try .5grams in a bit

 Rocket is around 40” tall so Kevlar is 3.6x the rocket length


On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@...> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:

I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Mark Joseph
 

Ah, your answers to Jonathan's questions clarified some things for me, too. I didn't pay enough attention to some of the details you mentioned, and misinterpreted the size of this rocket. The shock cord may, in fact be long enough, but if you have room for more - well, that almost never hurts.

If you're going to stick with friction fit, you'll just need to check the friction at each flight. As with smaller rockets, a common rule of thumb is that you should be able to hold the rocket up by the nose cone, fully loaded, and not have the parts separate. With very little effort, though, you should be able to pull it apart. Just add or remove tape as necessary when you're prepping the rocket. A fiberglass rocket won't vary as much as a paper tube one might, but you should still be prepared to check and adjust each time.

Smaller, repeatable charge sizes would be appropriate. As you note, small charges, or small changes to them, are really hard to consistently replicate from flight to flight. So stick with a simple way to measure - one that you can do over and over. 0.5g sounds like a good one to try.

Mark

-----
No shear pins. It’s friction fit. I plan to use tape instead of shear pins on the nose cone only. I had one calculator that said .3 grams. I was worried about getting consistent ignition with a charge that’d small I’ll try .5grams in a bit

Rocket is around 40” tall so Kevlar is 3.6x the rocket length
-----


________________________________________

From: cia-rocketry@groups.io <cia-rocketry@groups.io> on behalf of Mark Joseph <markjos@...>
Sent: Monday, April 13, 2020 3:33 PM
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

Hi Dan,

Don't apologize for the questions, please - all good stuff. Some comments and questions follow.

Still a pretty "enthusiastic" charge. And especially so with that length shock cord, which could easily stand to be twice that long. Ultimately, getting the chute all the way out of the airframe, so that it's fully exposed for easy opening, is the goal. Hitting the end of the shock cord length with a big jerk, and pulling the airframe along, is usually a sign that you've got too much.

Are you, in fact, separating at two different points - drogue compartment below, and main above?

Do you intend to use shear pins of some sort to hold parts together prior to deployment, or is this just friction-fit? Generally speaking, shear pinning is a good idea, at least for the section containing the Main parachute, to prevent it from prematurely opening when the drogue section shock cord fully extends (with a jerk).

For some of us, it helps to work backwards from the force required to separate the parts, which is derived from the number of shear pins used.

You can, if you want, run the charge down to the bottom of the airframe. That's a matter of personal preference.

I'm sure you'll hear from several of us on these points, and there are lots of ways to do it right. We can point you some more resources, too.

Mark

________________________________________
From: cia-rocketry@groups.io <cia-rocketry@groups.io> on behalf of Daniel Greuel <kc9thp@...>
Sent: Monday, April 13, 2020 3:02 PM
To: cia-rocketry@groups.io
Subject: [cia-rocketry] Ejection testing questions

I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Daniel Greuel
 




On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@...> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Daniel Greuel
 

Answering a couple guys. No shear pins. This is a conventional dual deploy drogue below and chute up top. Using an RRC2+ on a 3D printed sled of my own design so I could use a fingertech screw switch and a 1S lipo.  Plan on motor deploy as backup if it sims good. Might have to use the altimeter as a backup to the motor depending on the motor. I wanted to practice dual deploy without waiver on G53, G64 and G76.  Might try some larger single use at a club launch. 

IIRC it the early sims showed around 4000’ on a G76.  Going to try and test the RRC2+ With some Christmas tree bulbs and a vacuum sealer this week.  Hopefully if the weather is good next weekend I can get a G53  launch in with it behind the house 


On Apr 13, 2020, at 4:24 PM, Daniel Greuel via groups.io <kc9thp@...> wrote:


<image1.jpeg>


On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@...> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Mark Joseph
 

Sounds like fun, Dan. There's certainly some risk of having the main come out at apogee with friction fit on this, depending on the mass of the upper-most pieces - but you probably know that. A really visible or shiny/reflective streamer, or a radio tracking device might become your friend, given the altitude performance that's expected, and the rocket's small size.

We'll look forward to hearing more, and eventually seeing this fly together!

Mark

________________________________________

From: cia-rocketry@groups.io <cia-rocketry@groups.io> on behalf of Daniel Greuel <kc9thp@...>
Sent: Monday, April 13, 2020 4:57 PM
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

Answering a couple guys. No shear pins. This is a conventional dual deploy drogue below and chute up top. Using an RRC2+ on a 3D printed sled of my own design so I could use a fingertech screw switch and a 1S lipo. Plan on motor deploy as backup if it sims good. Might have to use the altimeter as a backup to the motor depending on the motor. I wanted to practice dual deploy without waiver on G53, G64 and G76. Might try some larger single use at a club launch.

IIRC it the early sims showed around 4000’ on a G76. Going to try and test the RRC2+ With some Christmas tree bulbs and a vacuum sealer this week. Hopefully if the weather is good next weekend I can get a G53 launch in with it behind the house


On Apr 13, 2020, at 4:24 PM, Daniel Greuel via groups.io <kc9thp@...> wrote:


<image1.jpeg>


On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@...> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Daniel Greuel
 

I finished my ground test and got a flight in on a G53 this weekend. I ended up extending my drogue harness to 20’ and running my 12’ on the main. .75grams on drogue and .5 grams on the main. Perfect flight at 1021’ except for the powder burns on my rocketman chute. 

Full disclosure. I mistated as some of you I sure realized realized. The project 4000’ was in an I200. (Living vicariously thru rocsim). A G64 should give me in the neighborhood of 1600’. 

Attached video is not the best. 

Thanks for your help
Dan



On Apr 13, 2020, at 5:19 PM, Mark Joseph <markjos@...> wrote:

Sounds like fun, Dan. There's certainly some risk of having the main come out at apogee with friction fit on this, depending on the mass of the upper-most pieces - but you probably know that. A really visible or shiny/reflective streamer, or a radio tracking device might become your friend, given the altitude performance that's expected, and the rocket's small size.

We'll look forward to hearing more, and eventually seeing this fly together!

Mark

________________________________________
From: cia-rocketry@groups.io <cia-rocketry@groups.io> on behalf of Daniel Greuel <kc9thp@...>
Sent: Monday, April 13, 2020 4:57 PM
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

Answering a couple guys. No shear pins. This is a conventional dual deploy drogue below and chute up top. Using an RRC2+ on a 3D printed sled of my own design so I could use a fingertech screw switch and a 1S lipo. Plan on motor deploy as backup if it sims good. Might have to use the altimeter as a backup to the motor depending on the motor. I wanted to practice dual deploy without waiver on G53, G64 and G76. Might try some larger single use at a club launch.

IIRC it the early sims showed around 4000’ on a G76. Going to try and test the RRC2+ With some Christmas tree bulbs and a vacuum sealer this week. Hopefully if the weather is good next weekend I can get a G53 launch in with it behind the house


On Apr 13, 2020, at 4:24 PM, Daniel Greuel via groups.io <kc9thp@...> wrote:


<image1.jpeg>


On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@...> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Jonathan Sivier
 

What size chute protector did you use? If you don't wrap your chute up well you can get powder burns like you mention.

Jonathan


On 4/20/2020 8:24 AM, Daniel Greuel wrote:
I finished my ground test and got a flight in on a G53 this weekend. I ended up extending my drogue harness to 20’ and running my 12’ on the main. .75grams on drogue and .5 grams on the main. Perfect flight at 1021’ except for the powder burns on my rocketman chute.

Full disclosure. I mistated as some of you I sure realized realized. The project 4000’ was in an I200. (Living vicariously thru rocsim). A G64 should give me in the neighborhood of 1600’.

Attached video is not the best.

Thanks for your help
Dan


Christopher Deem
 

Nice, I remember when we used to launch rockets back in the pre-plague years.



Sent from my Samsung Galaxy smartphone.


-------- Original message --------
From: Daniel Greuel <kc9thp@...>
Date: 4/20/20 8:31 AM (GMT-06:00)
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

I finished my ground test and got a flight in on a G53 this weekend. I ended up extending my drogue harness to 20’ and running my 12’ on the main. .75grams on drogue and .5 grams on the main. Perfect flight at 1021’ except for the powder burns on my rocketman chute. 

Full disclosure. I mistated as some of you I sure realized realized. The project 4000’ was in an I200. (Living vicariously thru rocsim). A G64 should give me in the neighborhood of 1600’. 

Attached video is not the best. 

Thanks for your help
Dan



On Apr 13, 2020, at 5:19 PM, Mark Joseph <markjos@...> wrote:

Sounds like fun, Dan. There's certainly some risk of having the main come out at apogee with friction fit on this, depending on the mass of the upper-most pieces - but you probably know that. A really visible or shiny/reflective streamer, or a radio tracking device might become your friend, given the altitude performance that's expected, and the rocket's small size.

We'll look forward to hearing more, and eventually seeing this fly together!

Mark

________________________________________
From: cia-rocketry@groups.io <cia-rocketry@groups.io> on behalf of Daniel Greuel <kc9thp@...>
Sent: Monday, April 13, 2020 4:57 PM
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

Answering a couple guys. No shear pins. This is a conventional dual deploy drogue below and chute up top. Using an RRC2+ on a 3D printed sled of my own design so I could use a fingertech screw switch and a 1S lipo. Plan on motor deploy as backup if it sims good. Might have to use the altimeter as a backup to the motor depending on the motor. I wanted to practice dual deploy without waiver on G53, G64 and G76. Might try some larger single use at a club launch.

IIRC it the early sims showed around 4000’ on a G76. Going to try and test the RRC2+ With some Christmas tree bulbs and a vacuum sealer this week. Hopefully if the weather is good next weekend I can get a G53 launch in with it behind the house


On Apr 13, 2020, at 4:24 PM, Daniel Greuel via groups.io <kc9thp@...> wrote:


<image1.jpeg>


On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@...> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Jonathan Sivier
 

Were you using a fly-away rail guide? I think I saw something like that just after launch.

Jonathan


On 4/20/2020 8:24 AM, Daniel Greuel wrote:
I finished my ground test and got a flight in on a G53 this weekend. I ended up extending my drogue harness to 20’ and running my 12’ on the main. .75grams on drogue and .5 grams on the main. Perfect flight at 1021’ except for the powder burns on my rocketman chute.

Full disclosure. I mistated as some of you I sure realized realized. The project 4000’ was in an I200. (Living vicariously thru rocsim). A G64 should give me in the neighborhood of 1600’.

Attached video is not the best.

Thanks for your help
Dan


Daniel Greuel
 

Johnathan,
Yes it is a fly away guide. I’m running a 6”x6” chute protector and dog barf anywhere I got a void which was about one caliber of space.  I only burrito wrapped the aft portion chute and had part of the chute (that got burnt of coarse) in the nose cone.  My fault.  1.5”x7” of compartment space disappears fast when packing. 

Christopher,
Yes, I’m fortunate to have permission from the farmers behind my house to launch.  Some day I might apply for a waiver and try some high power launches. 


On Apr 20, 2020, at 12:48 PM, Jonathan Sivier <jsivier@...> wrote:

Were you using a fly-away rail guide? I think I saw something like that just after launch.

Jonathan

On 4/20/2020 8:24 AM, Daniel Greuel wrote:
I finished my ground test and got a flight in on a G53 this weekend. I ended up extending my drogue harness to 20’ and running my 12’ on the main. .75grams on drogue and .5 grams on the main. Perfect flight at 1021’ except for the powder burns on my rocketman chute.

Full disclosure. I mistated as some of you I sure realized realized. The project 4000’ was in an I200. (Living vicariously thru rocsim). A G64 should give me in the neighborhood of 1600’.

Attached video is not the best.

Thanks for your help
Dan


Gary Slater
 

For some reason, I did not get Dan's email with the video nor do I see in subsequent replies.  Anyone?

On April 20, 2020 at 11:29 AM Christopher Deem <chris-deem@...> wrote:

Nice, I remember when we used to launch rockets back in the pre-plague years.



Sent from my Samsung Galaxy smartphone.


-------- Original message --------
From: Daniel Greuel <kc9thp@...>
Date: 4/20/20 8:31 AM (GMT-06:00)
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

I finished my ground test and got a flight in on a G53 this weekend. I ended up extending my drogue harness to 20’ and running my 12’ on the main. .75grams on drogue and .5 grams on the main. Perfect flight at 1021’ except for the powder burns on my rocketman chute. 

Full disclosure. I mistated as some of you I sure realized realized. The project 4000’ was in an I200. (Living vicariously thru rocsim). A G64 should give me in the neighborhood of 1600’. 

Attached video is not the best. 

Thanks for your help
Dan
 


 

On Apr 13, 2020, at 5:19 PM, Mark Joseph <markjos@...> wrote:

Sounds like fun, Dan. There's certainly some risk of having the main come out at apogee with friction fit on this, depending on the mass of the upper-most pieces - but you probably know that. A really visible or shiny/reflective streamer, or a radio tracking device might become your friend, given the altitude performance that's expected, and the rocket's small size.

We'll look forward to hearing more, and eventually seeing this fly together!

Mark

________________________________________
From: cia-rocketry@groups.io <cia-rocketry@groups.io> on behalf of Daniel Greuel <kc9thp@...>
Sent: Monday, April 13, 2020 4:57 PM
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

Answering a couple guys. No shear pins. This is a conventional dual deploy drogue below and chute up top. Using an RRC2+ on a 3D printed sled of my own design so I could use a fingertech screw switch and a 1S lipo. Plan on motor deploy as backup if it sims good. Might have to use the altimeter as a backup to the motor depending on the motor. I wanted to practice dual deploy without waiver on G53, G64 and G76. Might try some larger single use at a club launch.

IIRC it the early sims showed around 4000’ on a G76. Going to try and test the RRC2+ With some Christmas tree bulbs and a vacuum sealer this week. Hopefully if the weather is good next weekend I can get a G53 launch in with it behind the house


On Apr 13, 2020, at 4:24 PM, Daniel Greuel via groups.io <kc9thp@...> wrote:


<image1.jpeg>


On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@...> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan

 


Jonathan Sivier
 

You probably want to use a larger chute protector in future. Most people try to get the whole chute inside the "burrito". As you discovered any part of the chute that isn't covered can be exposed to the ejection charge. My impression is it isn't so much the hot gas from the combustion, but the small, still burning, particles that can put holes in your chute.

Jonathan


On 4/20/2020 1:26 PM, Daniel Greuel wrote:
Johnathan,
Yes it is a fly away guide. I’m running a 6”x6” chute protector and dog barf anywhere I got a void which was about one caliber of space.  I only burrito wrapped the aft portion chute and had part of the chute (that got burnt of coarse) in the nose cone.  My fault.  1.5”x7” of compartment space disappears fast when packing.

Christopher,
Yes, I’m fortunate to have permission from the farmers behind my house to launch.  Some day I might apply for a waiver and try some high power launches.


On Apr 20, 2020, at 12:48 PM, Jonathan Sivier <jsivier@...> wrote:

Were you using a fly-away rail guide? I think I saw something like that just after launch.

Jonathan

On 4/20/2020 8:24 AM, Daniel Greuel wrote:

I finished my ground test and got a flight in on a G53 this weekend. I ended up extending my drogue harness to 20’ and running my 12’ on the main. .75grams on drogue and .5 grams on the main. Perfect flight at 1021’ except for the powder burns on my rocketman chute.

Full disclosure. I mistated as some of you I sure realized realized. The project 4000’ was in an I200. (Living vicariously thru rocsim). A G64 should give me in the neighborhood of 1600’.

Attached video is not the best.

Thanks for your help
Dan


Jonathan Sivier
 

I'll send the video to Gary. It is possible that the large attachment caused the email to be blocked by his email provider.

Jonathan


On 4/20/2020 1:38 PM, Gary Slater wrote:
For some reason, I did not get Dan's email with the video nor do I see in subsequent replies.  Anyone?
On April 20, 2020 at 11:29 AM Christopher Deem <chris-deem@...> wrote:

Nice, I remember when we used to launch rockets back in the pre-plague years.



Sent from my Samsung Galaxy smartphone.


-------- Original message --------
From: Daniel Greuel <kc9thp@...>
Date: 4/20/20 8:31 AM (GMT-06:00)
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

I finished my ground test and got a flight in on a G53 this weekend. I ended up extending my drogue harness to 20’ and running my 12’ on the main. .75grams on drogue and .5 grams on the main. Perfect flight at 1021’ except for the powder burns on my rocketman chute.

Full disclosure. I mistated as some of you I sure realized realized. The project 4000’ was in an I200. (Living vicariously thru rocsim). A G64 should give me in the neighborhood of 1600’.

Attached video is not the best.

Thanks for your help
Dan





On Apr 13, 2020, at 5:19 PM, Mark Joseph <markjos@...> wrote:

Sounds like fun, Dan. There's certainly some risk of having the main come out at apogee with friction fit on this, depending on the mass of the upper-most pieces - but you probably know that. A really visible or shiny/reflective streamer, or a radio tracking device might become your friend, given the altitude performance that's expected, and the rocket's small size.

We'll look forward to hearing more, and eventually seeing this fly together!

Mark

________________________________________
From: cia-rocketry@groups.io <cia-rocketry@groups.io> on behalf of Daniel Greuel <kc9thp@...>
Sent: Monday, April 13, 2020 4:57 PM
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

Answering a couple guys. No shear pins. This is a conventional dual deploy drogue below and chute up top. Using an RRC2+ on a 3D printed sled of my own design so I could use a fingertech screw switch and a 1S lipo. Plan on motor deploy as backup if it sims good. Might have to use the altimeter as a backup to the motor depending on the motor. I wanted to practice dual deploy without waiver on G53, G64 and G76. Might try some larger single use at a club launch.

IIRC it the early sims showed around 4000’ on a G76. Going to try and test the RRC2+ With some Christmas tree bulbs and a vacuum sealer this week. Hopefully if the weather is good next weekend I can get a G53 launch in with it behind the house


On Apr 13, 2020, at 4:24 PM, Daniel Greuel via groups.io <kc9thp@...> wrote:


<image1.jpeg>


On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@...> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Wes Cravens
 

Ya, I can't remember what diameter your rocket is, but I use chute protectors most of the time on my 3" + rockets and the smallest I use is 12" square.

Wes

On Mon, Apr 20, 2020 at 1:50 PM Jonathan Sivier <jsivier@...> wrote:
I'll send the video to Gary. It is possible that the large attachment caused the email to be blocked by his email provider.

Jonathan

On 4/20/2020 1:38 PM, Gary Slater wrote:
For some reason, I did not get Dan's email with the video nor do I see in subsequent replies.  Anyone?
On April 20, 2020 at 11:29 AM Christopher Deem <chris-deem@...> wrote:

Nice, I remember when we used to launch rockets back in the pre-plague years.



Sent from my Samsung Galaxy smartphone.


-------- Original message --------
From: Daniel Greuel <kc9thp@...>
Date: 4/20/20 8:31 AM (GMT-06:00)
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

I finished my ground test and got a flight in on a G53 this weekend. I ended up extending my drogue harness to 20’ and running my 12’ on the main. .75grams on drogue and .5 grams on the main. Perfect flight at 1021’ except for the powder burns on my rocketman chute.

Full disclosure. I mistated as some of you I sure realized realized. The project 4000’ was in an I200. (Living vicariously thru rocsim). A G64 should give me in the neighborhood of 1600’.

Attached video is not the best.

Thanks for your help
Dan





On Apr 13, 2020, at 5:19 PM, Mark Joseph <markjos@...> wrote:

Sounds like fun, Dan. There's certainly some risk of having the main come out at apogee with friction fit on this, depending on the mass of the upper-most pieces - but you probably know that. A really visible or shiny/reflective streamer, or a radio tracking device might become your friend, given the altitude performance that's expected, and the rocket's small size.

We'll look forward to hearing more, and eventually seeing this fly together!

Mark

________________________________________
From: cia-rocketry@groups.io <cia-rocketry@groups.io> on behalf of Daniel Greuel <kc9thp@...>
Sent: Monday, April 13, 2020 4:57 PM
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

Answering a couple guys. No shear pins. This is a conventional dual deploy drogue below and chute up top. Using an RRC2+ on a 3D printed sled of my own design so I could use a fingertech screw switch and a 1S lipo. Plan on motor deploy as backup if it sims good. Might have to use the altimeter as a backup to the motor depending on the motor. I wanted to practice dual deploy without waiver on G53, G64 and G76. Might try some larger single use at a club launch.

IIRC it the early sims showed around 4000’ on a G76. Going to try and test the RRC2+ With some Christmas tree bulbs and a vacuum sealer this week. Hopefully if the weather is good next weekend I can get a G53 launch in with it behind the house


On Apr 13, 2020, at 4:24 PM, Daniel Greuel via groups.io <kc9thp=gmail.com@groups.io> wrote:


<image1.jpeg>


On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@...> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Jonathan Sivier
 

Some places suggest sizes of chute protectors based on the size of the body tube. My impression is that this would be useful for the case where you are using the protector in much the same manner we typically use wadding. It fills the body tube diameter and sits between the ejection charge and the parachute. So larger tubes would use larger protectors and smaller tubes use smaller ones. It you are using the chute protector to wrap up the chute in a "burrito" then the size of the protector would be based on the size of the chute when it is folded. It wouldn't be directly related to the size of the body tube. Of course, a larger rocket is likely to need a larger parachute, and thus a larger chute protector. I don't recall having seen any listing of chute protector size vs. parachute size anywhere. To some degree this will depend on how small you can fold the parachute and that will depend in part on the material the chute is made from, as well as your skill in folding the chute. So it would be difficult to make a definitive listing of chute protectors to parachute size.

Jonathan


On 4/20/2020 1:53 PM, Wes Cravens wrote:
Ya, I can't remember what diameter your rocket is, but I use chute protectors most of the time on my 3" + rockets and the smallest I use is 12" square.

Wes

On Mon, Apr 20, 2020 at 1:50 PM Jonathan Sivier <jsivier@... <mailto:jsivier@...>> wrote:

I'll send the video to Gary. It is possible that the large attachment caused the email to be blocked by his email provider.

Jonathan

On 4/20/2020 1:38 PM, Gary Slater wrote:

For some reason, I did not get Dan's email with the video nor do I see in subsequent replies.  Anyone?

On April 20, 2020 at 11:29 AM Christopher Deem <chris-deem@... <mailto:chris-deem@...>> wrote:

Nice, I remember when we used to launch rockets back in the pre-plague years.



Sent from my Samsung Galaxy smartphone.


-------- Original message --------
From: Daniel Greuel <kc9thp@... <mailto:kc9thp@...>>
Date: 4/20/20 8:31 AM (GMT-06:00)
To: cia-rocketry@groups.io <mailto:cia-rocketry@groups.io>
Subject: Re: [cia-rocketry] Ejection testing questions

I finished my ground test and got a flight in on a G53 this weekend. I ended up extending my drogue harness to 20’ and running my 12’ on the main. .75grams on drogue and .5 grams on the main. Perfect flight at 1021’ except for the powder burns on my rocketman chute.

Full disclosure. I mistated as some of you I sure realized realized. The project 4000’ was in an I200. (Living vicariously thru rocsim). A G64 should give me in the neighborhood of 1600’.

Attached video is not the best.

Thanks for your help
Dan





On Apr 13, 2020, at 5:19 PM, Mark Joseph <markjos@... <mailto:markjos@...>> wrote:

Sounds like fun, Dan. There's certainly some risk of having the main come out at apogee with friction fit on this, depending on the mass of the upper-most pieces - but you probably know that. A really visible or shiny/reflective streamer, or a radio tracking device might become your friend, given the altitude performance that's expected, and the rocket's small size.

We'll look forward to hearing more, and eventually seeing this fly together!

Mark

________________________________________
From: cia-rocketry@groups.io <mailto:cia-rocketry@groups.io> <cia-rocketry@groups.io <mailto:cia-rocketry@groups.io>> on behalf of Daniel Greuel <kc9thp@... <mailto:kc9thp@...>>
Sent: Monday, April 13, 2020 4:57 PM
To: cia-rocketry@groups.io <mailto:cia-rocketry@groups.io>
Subject: Re: [cia-rocketry] Ejection testing questions

Answering a couple guys. No shear pins. This is a conventional dual deploy drogue below and chute up top. Using an RRC2+ on a 3D printed sled of my own design so I could use a fingertech screw switch and a 1S lipo. Plan on motor deploy as backup if it sims good. Might have to use the altimeter as a backup to the motor depending on the motor. I wanted to practice dual deploy without waiver on G53, G64 and G76. Might try some larger single use at a club launch.

IIRC it the early sims showed around 4000’ on a G76. Going to try and test the RRC2+ With some Christmas tree bulbs and a vacuum sealer this week. Hopefully if the weather is good next weekend I can get a G53 launch in with it behind the house


On Apr 13, 2020, at 4:24 PM, Daniel Greuel via groups.io <http://groups.io> <kc9thp@... <mailto:gmail.com@groups.io>> wrote:


<image1.jpeg>


On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@... <mailto:jsivier@...>> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan


Christopher Deem
 

Some of the parachute protectors I've bought reccomend a little dog barf on top of the motor. I guess to catch the burning particles.



Sent from my Samsung Galaxy smartphone.


-------- Original message --------
From: Jonathan Sivier <jsivier@...>
Date: 4/20/20 2:04 PM (GMT-06:00)
To: cia-rocketry@groups.io
Subject: Re: [cia-rocketry] Ejection testing questions

Some places suggest sizes of chute protectors based on the size of the body tube. My impression is that this would be useful for the case where you are using the protector in much the same manner we typically use wadding. It fills the body tube diameter and sits between the ejection charge and the parachute. So larger tubes would use larger protectors and smaller tubes use smaller ones. It you are using the chute protector to wrap up the chute in a "burrito" then the size of the protector would be based on the size of the chute when it is folded. It wouldn't be directly related to the size of the body tube. Of course, a larger rocket is likely to need a larger parachute, and thus a larger chute protector. I don't recall having seen any listing of chute protector size vs. parachute size anywhere. To some degree this will depend on how small you can fold the parachute and that will depend in part on the material the chute is made from, as well as your skill in folding the chute. So it would be difficult to make a definitive listing of chute protectors to parachute size.

Jonathan

On 4/20/2020 1:53 PM, Wes Cravens wrote:
Ya, I can't remember what diameter your rocket is, but I use chute protectors most of the time on my 3" + rockets and the smallest I use is 12" square.

Wes

On Mon, Apr 20, 2020 at 1:50 PM Jonathan Sivier <jsivier@... <mailto:jsivier@...>> wrote:

I'll send the video to Gary. It is possible that the large attachment caused the email to be blocked by his email provider.

Jonathan

On 4/20/2020 1:38 PM, Gary Slater wrote:

For some reason, I did not get Dan's email with the video nor do I see in subsequent replies.  Anyone?

On April 20, 2020 at 11:29 AM Christopher Deem <chris-deem@... <mailto:chris-deem@...>> wrote:

Nice, I remember when we used to launch rockets back in the pre-plague years.



Sent from my Samsung Galaxy smartphone.


-------- Original message --------
From: Daniel Greuel <kc9thp@... <mailto:kc9thp@...>>
Date: 4/20/20 8:31 AM (GMT-06:00)
To: cia-rocketry@groups.io <mailto:cia-rocketry@groups.io>
Subject: Re: [cia-rocketry] Ejection testing questions

I finished my ground test and got a flight in on a G53 this weekend. I ended up extending my drogue harness to 20’ and running my 12’ on the main. .75grams on drogue and .5 grams on the main. Perfect flight at 1021’ except for the powder burns on my rocketman chute.

Full disclosure. I mistated as some of you I sure realized realized. The project 4000’ was in an I200. (Living vicariously thru rocsim). A G64 should give me in the neighborhood of 1600’.

Attached video is not the best.

Thanks for your help
Dan





On Apr 13, 2020, at 5:19 PM, Mark Joseph <markjos@... <mailto:markjos@...>> wrote:

Sounds like fun, Dan. There's certainly some risk of having the main come out at apogee with friction fit on this, depending on the mass of the upper-most pieces - but you probably know that. A really visible or shiny/reflective streamer, or a radio tracking device might become your friend, given the altitude performance that's expected, and the rocket's small size.

We'll look forward to hearing more, and eventually seeing this fly together!

Mark

________________________________________
From: cia-rocketry@groups.io <mailto:cia-rocketry@groups.io> <cia-rocketry@groups.io <mailto:cia-rocketry@groups.io>> on behalf of Daniel Greuel <kc9thp@... <mailto:kc9thp@...>>
Sent: Monday, April 13, 2020 4:57 PM
To: cia-rocketry@groups.io <mailto:cia-rocketry@groups.io>
Subject: Re: [cia-rocketry] Ejection testing questions

Answering a couple guys. No shear pins. This is a conventional dual deploy drogue below and chute up top. Using an RRC2+ on a 3D printed sled of my own design so I could use a fingertech screw switch and a 1S lipo. Plan on motor deploy as backup if it sims good. Might have to use the altimeter as a backup to the motor depending on the motor. I wanted to practice dual deploy without waiver on G53, G64 and G76. Might try some larger single use at a club launch.

IIRC it the early sims showed around 4000’ on a G76. Going to try and test the RRC2+ With some Christmas tree bulbs and a vacuum sealer this week. Hopefully if the weather is good next weekend I can get a G53 launch in with it behind the house


On Apr 13, 2020, at 4:24 PM, Daniel Greuel via groups.io <http://groups.io> <kc9thp@... <mailto:gmail.com@groups.io>> wrote:


<image1.jpeg>


On Apr 13, 2020, at 3:27 PM, Jonathan Sivier <jsivier@... <mailto:jsivier@...>> wrote:

My impression from your video is you can certainly make do with less powder. Are you using shear pins? If so, how many and how large? One of the calculators I use says 0.2 grams in a compartment that small. I'm not sure if I agree with that and using less than 0.5 grams is a challenge. I would probably try 0.5 grams and then increase by 0.25 gram increments until I got an acceptable result.

Jonathan

On 4/13/2020 3:02 PM, Daniel Greuel wrote:
I’m testing ejection charges for a 38mm Wildman intimidator dual deploy today. I built this to fly on 29mm hobbyline reloads behind the house. My drogue compartment is 1.5” x14” containing a streamer with a 12’ Kevlar shock cord. I first used an online calculator and decided on 2 grams of 4g targeting about 15psi. Way to much.

Next I tried 1.3 g with an expected 10psi. I’ve attached a slo-mo video with the results. Still plenty of pressure. Do you guys think I should make a longer Kevlar harness? Or lower the charge? Leave it?

Also. I’m running the ejection charge at the aft end at the motor ejection well. When running dual deploy does it work to run a longer wire on the drogue to put the charge below the laundry? I’m hot gluing the igniters in shake straws for canisters.

Sorry for all the questions. New to dual deploy. Thanks

Dan