Head-End Dual Deployment Details & Explanations Requested
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Ah good one, I have been wondering about the best way to do HED for my Punisher. Big fan of pictures with detailed descriptions please!
stealth6
insert witty tagline here
First of all, I think you need to define which setup you are referring to as "HED". There are two different types of "deploy from the nose" that I can think of, and that some folks refer to as "Head End":
The first is: A) avionics located in the nose cone and the airframe is one piece. Often uses single deploy, but can be done as dual deploy utilizing something such as a CableCutter or TenderDescender. I'm pretty sure this is NOT what you are asking about.
The second is: B) a setup such as used in the Wildman Punisher, wherein there is no* "payload" section of airframe, and the main chute is housed in the nosecone. I think this is what you are asking about. This is also what I think of and refer to as "HED" or "Head End Deployment".
So, my thoughts notes on option B -
I wish you had asked before this weekend as I would have been happy to show you my setup on my own Punisher (which I flew twice at Vegas Oktoberfest with great results). That said, HED like this is actually quite simple and straightforward. It's almost the same thing as a "normal" DD setup in fact. You still have an AV bay that looks and functions just like in most rockets. Below it, the whole airframe is what you would normally think of as your "fincan" section, and it houses your drogue and harness just like normal. Above it, all that's missing is your "payload" section of airframe. Instead, the shoulder end of the nosecone is a bit longer than usual. All you do is shove your mains chute and harness into the nose cone, and slide your AV bay into that short straight section. You still use shear pins to hold the nosecone on, you simply pin it to the AV bay coupler.
In the case of a Punisher, which has a nosecone specifically designed to be used in this fashion, there's plenty of room for an appropriately sized chute to fit. If you want to use the HED method on another rocket that uses a "normal" nosecone, all you need to do is to permanently glue a short section of airframe to your nosecone shoulder (just long enough to allow the forward end of the AV bay to slide into it.
I can't post any pics right now, but it's pretty clear looking at it, and you soon realize that it's really not that much different than normal. Honestly, it's so straightforward that I bet it was just pure coincidence that we view the standard way AS the standard, just by the pure luck chance that it was how things were done first. If HED had been thought of at the beginning, we would all be doing it as the normal way I bet.
And it works great.
CJim and lots of others will have more info to add I'm sure.
s6
* = It's not actually true that there is "no payload section of airframe". In actuality, there IS a short section of payload. The difference is that it's part of the nosecone. In the case of a Punisher, it's molded into the nosecone itself so it's all one piece. If you want to do HED with a "normal" nosecone, all you have to do is glue a short section of airframe onto the nosecone shoulder and voila, you have a homemade HED nosecone.
The first is: A) avionics located in the nose cone and the airframe is one piece. Often uses single deploy, but can be done as dual deploy utilizing something such as a CableCutter or TenderDescender. I'm pretty sure this is NOT what you are asking about.
The second is: B) a setup such as used in the Wildman Punisher, wherein there is no* "payload" section of airframe, and the main chute is housed in the nosecone. I think this is what you are asking about. This is also what I think of and refer to as "HED" or "Head End Deployment".
So, my thoughts notes on option B -
I wish you had asked before this weekend as I would have been happy to show you my setup on my own Punisher (which I flew twice at Vegas Oktoberfest with great results). That said, HED like this is actually quite simple and straightforward. It's almost the same thing as a "normal" DD setup in fact. You still have an AV bay that looks and functions just like in most rockets. Below it, the whole airframe is what you would normally think of as your "fincan" section, and it houses your drogue and harness just like normal. Above it, all that's missing is your "payload" section of airframe. Instead, the shoulder end of the nosecone is a bit longer than usual. All you do is shove your mains chute and harness into the nose cone, and slide your AV bay into that short straight section. You still use shear pins to hold the nosecone on, you simply pin it to the AV bay coupler.
In the case of a Punisher, which has a nosecone specifically designed to be used in this fashion, there's plenty of room for an appropriately sized chute to fit. If you want to use the HED method on another rocket that uses a "normal" nosecone, all you need to do is to permanently glue a short section of airframe to your nosecone shoulder (just long enough to allow the forward end of the AV bay to slide into it.
I can't post any pics right now, but it's pretty clear looking at it, and you soon realize that it's really not that much different than normal. Honestly, it's so straightforward that I bet it was just pure coincidence that we view the standard way AS the standard, just by the pure luck chance that it was how things were done first. If HED had been thought of at the beginning, we would all be doing it as the normal way I bet.
And it works great.
CJim and lots of others will have more info to add I'm sure.
s6
* = It's not actually true that there is "no payload section of airframe". In actuality, there IS a short section of payload. The difference is that it's part of the nosecone. In the case of a Punisher, it's molded into the nosecone itself so it's all one piece. If you want to do HED with a "normal" nosecone, all you have to do is glue a short section of airframe onto the nosecone shoulder and voila, you have a homemade HED nosecone.
Viperfixr
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Got interrupted at work before I could finish this...I plan on doing my first HED rocket next, but still fuzzy on how best to implement it. I tried a kind of HED with a Wildman Gizmo once, and it did not work out great--one out of three attempts good.
For those of you who have successfully done Head End Dual Deployment, please describe the details of how you implemented HED.
- Where did you place the ejection charges?
- How did you contain the ejection charges?
- How did you protect the chute?
- What kind of recovery harness? How long?
- Drogue used either above or below nosecone av-bay?
- Where did you put the av-bay vent holes?
- What kind of av-bay switch did you use? Where located?
- What 'order' did you stuff the nosecone with?
- Any other devices like tethers used?
- Any lessons learned or tips for successful implementation?
Pictures are also worth 1000 words if any of you HED experts have them. Thank you in advance for your time & sharing.
For those of you who have successfully done Head End Dual Deployment, please describe the details of how you implemented HED.
- Where did you place the ejection charges?
- How did you contain the ejection charges?
- How did you protect the chute?
- What kind of recovery harness? How long?
- Drogue used either above or below nosecone av-bay?
- Where did you put the av-bay vent holes?
- What kind of av-bay switch did you use? Where located?
- What 'order' did you stuff the nosecone with?
- Any other devices like tethers used?
- Any lessons learned or tips for successful implementation?
Pictures are also worth 1000 words if any of you HED experts have them. Thank you in advance for your time & sharing.
Titan II
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3" Wildman...option B as noted above.
Ejection charges two on top and one or two on bottom of ebay bulkheads....in rubber glove fingers.
Chutes in nomex burritos.
Kevlar harness, bundled and taped. About 15' each.
Drogue below.
Ebay vent holes...three on switch band.
Payload vent about halfway up nosecone.
Switches can be seen in picture. This was before I switched to twist and tape.
Main chute about 3' from nosecone. Basically packed just like if you had a payload section.
Works great.
Ejection charges two on top and one or two on bottom of ebay bulkheads....in rubber glove fingers.
Chutes in nomex burritos.
Kevlar harness, bundled and taped. About 15' each.
Drogue below.
Ebay vent holes...three on switch band.
Payload vent about halfway up nosecone.
Switches can be seen in picture. This was before I switched to twist and tape.
Main chute about 3' from nosecone. Basically packed just like if you had a payload section.
Works great.
Option B is what I am after. Not to hijack Viperfixr's thread but I think he is after the same thing.
As with most techniques in this hobby there are likely some minor tweaks some of you will have so it would be great to see the variations, so some pics and descriptions of the setup to go along with the pictures would certainly help.
ChrisAttebery
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I have a 7.5" LOC DoorKnob that I've set up for single break with a cable cutter as described in section A. Both times I've tried to use it the main has deployed at apogee.
My 3" Wildman Saab (basically a Punisher with different fins) is set up for dual deploy with the chute in the nose cone as described in section B. It has worked perfectly both times I've flown it.
My 3" Wildman Saab (basically a Punisher with different fins) is set up for dual deploy with the chute in the nose cone as described in section B. It has worked perfectly both times I've flown it.
stealth6
insert witty tagline here
I should preface this by stating that in no way do I think of myself as "an expert", but for what it's worth, here's some response on how it's worked for me.
For those of you who have successfully done Head End Dual Deployment, please describe the details of how you implemented HED.
- Where did you place the ejection charges?
-------- Pretty standard terminal blocks on the outside of the AV bay bulkheads.
- How did you contain the ejection charges?
---------I drill a hole in the tip of centrifuge vials, hot glue a Q2G2 (or ematch) in, and fill with pre-measured amount of BP. Simply wire these into the terminal blocks such that they fire next to the AV bay bulkheads (I do put a layer of tape over the terminal strips and ends of all thread to protect them from fouling up from the charge firing). The "glove tip method" would work just fine as well.
- How did you protect the chute?
---------Standard burrito wrap with nomex cloth. I do make my own that are double thick (which in this instance I think a good idea).
- What kind of recovery harness? How long?
--------- Standard Kevlar cord, in my Punisher I think I used 21' for the fincan/drogue, and 17' for the nosecone/main.
- Drogue used either above or below nosecone av-bay?
----------Definitely drogue below (in the fincan), and mains above (in the nosecone).
- Where did you put the av-bay vent holes?
----------Again, pretty standard - I use a vent band and the three vent holes are located there.
- What kind of av-bay switch did you use? Where located?
----------Two switches (redundant avionics), I used Missileworks screw switches, accessed through the vent holes in the switch band. I do have a unique way of mounting these to the sled, but it's kinda hard to explain without pics (which I will try to load later). That said, there's no particular reason you can't do a normal type of mounting.
- What 'order' did you stuff the nosecone with?
----------From the eyebolt threaded into the nose cone tip: forward end of harness ties directly to that (and stays there permanently), the chute is attached to the harness fairly close to the nosecone BUT..., I stuff most of the neatly bundled length of harness in next, followed by the nomex wrapped chute, and lastly I put in a handful of "dogbarf".
- Any other devices like tethers used?
----------No special, extra, or unusual "devices" used.
- Any lessons learned or tips for successful implementation?
-----------I did really think about putting the deployment charges on longer leads so that I could stuff those into the tip of the nosecone, the thinking being that it would push the chute out more reliably (seeing as how in theory the chute would be pushed INTO the nosecone at deployment as it stands). In practice I've found (as has CJim) that this is simply unnecessary.
-----------I tend to use larger chutes than most people do (hard landing surfaces) which means that my idea of a "standard" sized chute might be a tight fit, and so I hedged my bets and got a FruityChute for this. The reasoning was that for a given amount of CD, these chutes pack much smaller than most other options. Since the space for a mains chute IS limited, this seemed like a good idea. It works great, and I would definitely encourage folks to think of chutes that pack as small as they can.
-----------If you tend to fly drogueless, I would NOT recommend doing so with this design. Since you have a full length airframe, it won't likely flat fall without a drogue to control it. A small droque is a good idea (I use a 13" with the Punisher).
------------For the maiden flight I would highly recommend making sure that you actually arm your electronics before pushing the launch button. This will ensure that all the other things mentioned above will work the way they are supposed to, and you will avoid a ballistic landing. Ask me how I know this.
s6
For those of you who have successfully done Head End Dual Deployment, please describe the details of how you implemented HED.
- Where did you place the ejection charges?
-------- Pretty standard terminal blocks on the outside of the AV bay bulkheads.
- How did you contain the ejection charges?
---------I drill a hole in the tip of centrifuge vials, hot glue a Q2G2 (or ematch) in, and fill with pre-measured amount of BP. Simply wire these into the terminal blocks such that they fire next to the AV bay bulkheads (I do put a layer of tape over the terminal strips and ends of all thread to protect them from fouling up from the charge firing). The "glove tip method" would work just fine as well.
- How did you protect the chute?
---------Standard burrito wrap with nomex cloth. I do make my own that are double thick (which in this instance I think a good idea).
- What kind of recovery harness? How long?
--------- Standard Kevlar cord, in my Punisher I think I used 21' for the fincan/drogue, and 17' for the nosecone/main.
- Drogue used either above or below nosecone av-bay?
----------Definitely drogue below (in the fincan), and mains above (in the nosecone).
- Where did you put the av-bay vent holes?
----------Again, pretty standard - I use a vent band and the three vent holes are located there.
- What kind of av-bay switch did you use? Where located?
----------Two switches (redundant avionics), I used Missileworks screw switches, accessed through the vent holes in the switch band. I do have a unique way of mounting these to the sled, but it's kinda hard to explain without pics (which I will try to load later). That said, there's no particular reason you can't do a normal type of mounting.
- What 'order' did you stuff the nosecone with?
----------From the eyebolt threaded into the nose cone tip: forward end of harness ties directly to that (and stays there permanently), the chute is attached to the harness fairly close to the nosecone BUT..., I stuff most of the neatly bundled length of harness in next, followed by the nomex wrapped chute, and lastly I put in a handful of "dogbarf".
- Any other devices like tethers used?
----------No special, extra, or unusual "devices" used.
- Any lessons learned or tips for successful implementation?
-----------I did really think about putting the deployment charges on longer leads so that I could stuff those into the tip of the nosecone, the thinking being that it would push the chute out more reliably (seeing as how in theory the chute would be pushed INTO the nosecone at deployment as it stands). In practice I've found (as has CJim) that this is simply unnecessary.
-----------I tend to use larger chutes than most people do (hard landing surfaces) which means that my idea of a "standard" sized chute might be a tight fit, and so I hedged my bets and got a FruityChute for this. The reasoning was that for a given amount of CD, these chutes pack much smaller than most other options. Since the space for a mains chute IS limited, this seemed like a good idea. It works great, and I would definitely encourage folks to think of chutes that pack as small as they can.
-----------If you tend to fly drogueless, I would NOT recommend doing so with this design. Since you have a full length airframe, it won't likely flat fall without a drogue to control it. A small droque is a good idea (I use a 13" with the Punisher).
------------For the maiden flight I would highly recommend making sure that you actually arm your electronics before pushing the launch button. This will ensure that all the other things mentioned above will work the way they are supposed to, and you will avoid a ballistic landing. Ask me how I know this.
s6
Last edited:
KenRico
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I flew my Punisher at Oktoberfest utilizing HEDR .
Shruter switches were in the vent band and had connectors to be able to disconnect from sled . Forged eyebolt, pair of Doghouse 1.5g charge wells and 4 position terminal strips on each lid. Put nose between legs, lightly packed 15 ft MPR 1/8th inch Kevlar forward, 24 inch PML parachute w/swivel wrapped in a nomex placed in next, then insert coupler and feel it fully seat before flipping over to screw in shear pins.
Being able to see most of the laundry forward of the shoulder lip in the nosecone before inserting coupler is very helpful ..have found as long as i don't pinch any kevlar or laundry under lip the coupler seats well without binding .
Kenny
Shruter switches were in the vent band and had connectors to be able to disconnect from sled . Forged eyebolt, pair of Doghouse 1.5g charge wells and 4 position terminal strips on each lid. Put nose between legs, lightly packed 15 ft MPR 1/8th inch Kevlar forward, 24 inch PML parachute w/swivel wrapped in a nomex placed in next, then insert coupler and feel it fully seat before flipping over to screw in shear pins.
Being able to see most of the laundry forward of the shoulder lip in the nosecone before inserting coupler is very helpful ..have found as long as i don't pinch any kevlar or laundry under lip the coupler seats well without binding .
Kenny
Here is a link to CJ's Punisher build - pretty detailed about the HED deploy, starts right around post #159
https://www.rocketryforum.com/showt...ot-PUNISHER-quot-build!&p=1395256#post1395256
https://www.rocketryforum.com/showt...ot-PUNISHER-quot-build!&p=1395256#post1395256
KenRico
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I flew my Punisher at Oktoberfest utilizing HEDR .
Shruter switches were in the vent band and had connectors to be able to disconnect from sled . Forged eyebolt, pair of Doghouse 1.5g charge wells and 4 position terminal strips on each lid. Put nose between legs, lightly packed 15 ft MPR 1/8th inch Kevlar forward, 24 inch PML parachute w/swivel wrapped in a nomex placed in next, then insert coupler and feel it fully seat before flipping over to screw in shear pins.
Being able to see most of the laundry forward of the shoulder lip in the nosecone before inserting coupler is very helpful ..have found as long as i don't pinch any kevlar or laundry under lip the coupler seats well without binding .
Will do a sled with Wifi Switches next and 2 small altimeters. Then will do a new avbay with TRS and no all thread for a 3rd revision. Rockets like the Punisher or nosecone avbay are real performers and budget friendly .. so is worth the time to try a few new things .
Kenny
Shruter switches were in the vent band and had connectors to be able to disconnect from sled . Forged eyebolt, pair of Doghouse 1.5g charge wells and 4 position terminal strips on each lid. Put nose between legs, lightly packed 15 ft MPR 1/8th inch Kevlar forward, 24 inch PML parachute w/swivel wrapped in a nomex placed in next, then insert coupler and feel it fully seat before flipping over to screw in shear pins.
Being able to see most of the laundry forward of the shoulder lip in the nosecone before inserting coupler is very helpful ..have found as long as i don't pinch any kevlar or laundry under lip the coupler seats well without binding .
Will do a sled with Wifi Switches next and 2 small altimeters. Then will do a new avbay with TRS and no all thread for a 3rd revision. Rockets like the Punisher or nosecone avbay are real performers and budget friendly .. so is worth the time to try a few new things .
Kenny
stealth6
insert witty tagline here
36".
Yep, a lot of folks will be thinking, "that's a big chute for that rocket". Like I said, I tend to oversize my chutes. After far too many hard landings with "normal" sized chutes resulting in damage, I started using bigger chutes and now I spend a lot less time doing repairs. There it is.
s6
CzTeacherMan
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Here, check this out: ...HED Directions in downloadable, printable format, WITH pictures
https://goo.gl/M17GlW
Citation props go to CJ and his Punisher thread. These directions belong to Wildman (I just made them look pretty)
https://goo.gl/M17GlW
Citation props go to CJ and his Punisher thread. These directions belong to Wildman (I just made them look pretty)
watermelonman
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HED rule 1: no pyrodex. Yeesh.
stealth6
insert witty tagline here
Here's another way of looking at it.....
In this first graphic, you can see the difference between a "standard" DD setup and a Punisher-style HED one. Note that the green sections are an airframe diameter, and the yellow sections are a coupler diameter - the yellow/coupler pieces slide into the green/airframe pieces. You can see that there really isn't a huge difference between the two setups - the AV bay is pretty much identical, the fincan is essentially the same thing only longer. The main difference is that the nosecone, instead of having a normal shoulder (coupler diameter), has an extended bit of length on the open end that is airframe diameter. The AV bay (which is coupler diameter) slides into that. You would still shear-pin the nosecone on, only your pins in the HED setup would go through the nosecone and into the AV bay, rather than through the payload section into the nosecone shoulder.
Note also that the nosecone shown is specially made for the Punisher kit, and it makes the whole HED style setup really slick. That said, it's really not difficult to make your own - if you start with a hollow nose cone (especially one that has a removable tip that you can thread an eyebolt into), all you need to do is to glue a short section of airframe onto the existing shoulder; though not as stylie as the Punisher cone it works on the same principle.
In this second graphic you can see how the harnesses and chutes attach. Again, it's not that radically different than normal - the drogue in the fincan section is virtually identical, and the main (attached to the forward end of the AV bay like usual) simply goes up inside the nosecone rather than in a payload section of airframe between the AV and the nosecone.
Your AV bay can be set up the same way you always do - using a switchband for vent holes and switch access, charge cups on the bulkheads (apogee on rear, mains on forward), anchor points to attach harness, etc. You can also utilize common alternatives to some of these details such as no switchband, no charge cups, etc. if you wish to.
Hopefully these graphics make sense to some folk, and that they can see that HED deployment is really pretty simple/straightforward. Yes, you have to make some mental & physical adjustments (like making sure your chute is packed really well/small), but nothing really radical. For my money, HED deployment makes so much sense, and I was super psyched when Wildman started making and offering these nosecones. Get & build a Punisher (or other Wildman HED kit), or build your own HED-style rocket with standard parts - either way, you're going to love flying HED.
s6
In this first graphic, you can see the difference between a "standard" DD setup and a Punisher-style HED one. Note that the green sections are an airframe diameter, and the yellow sections are a coupler diameter - the yellow/coupler pieces slide into the green/airframe pieces. You can see that there really isn't a huge difference between the two setups - the AV bay is pretty much identical, the fincan is essentially the same thing only longer. The main difference is that the nosecone, instead of having a normal shoulder (coupler diameter), has an extended bit of length on the open end that is airframe diameter. The AV bay (which is coupler diameter) slides into that. You would still shear-pin the nosecone on, only your pins in the HED setup would go through the nosecone and into the AV bay, rather than through the payload section into the nosecone shoulder.
Note also that the nosecone shown is specially made for the Punisher kit, and it makes the whole HED style setup really slick. That said, it's really not difficult to make your own - if you start with a hollow nose cone (especially one that has a removable tip that you can thread an eyebolt into), all you need to do is to glue a short section of airframe onto the existing shoulder; though not as stylie as the Punisher cone it works on the same principle.
In this second graphic you can see how the harnesses and chutes attach. Again, it's not that radically different than normal - the drogue in the fincan section is virtually identical, and the main (attached to the forward end of the AV bay like usual) simply goes up inside the nosecone rather than in a payload section of airframe between the AV and the nosecone.
Your AV bay can be set up the same way you always do - using a switchband for vent holes and switch access, charge cups on the bulkheads (apogee on rear, mains on forward), anchor points to attach harness, etc. You can also utilize common alternatives to some of these details such as no switchband, no charge cups, etc. if you wish to.
Hopefully these graphics make sense to some folk, and that they can see that HED deployment is really pretty simple/straightforward. Yes, you have to make some mental & physical adjustments (like making sure your chute is packed really well/small), but nothing really radical. For my money, HED deployment makes so much sense, and I was super psyched when Wildman started making and offering these nosecones. Get & build a Punisher (or other Wildman HED kit), or build your own HED-style rocket with standard parts - either way, you're going to love flying HED.
s6
Iris or Elliptical?
Thay must come in pretty fast with the 24" chute!
Not necessarily. I've been using it with good results in my 3" Punisher HED, but:
1) You need more (like ~30% more)
2) You need to contain it so it doesn't push itself out unburned. I use glove tips inserted into charge wells then I tape it VERY tightly with electrical tape (thanks to cbrarick for this tip!).
3) Ground Test!!!
4) See #3, repeat a bunch more times, add a bit more (0.1-0.2 gram) for launch. If at all unsure, start higher and work down til failure, then up again to safe margin.
YMMV, but I have to work with what I have and I have it working. After my experiences, I lovingly refer to it as "Puss-o-dex". :wink:
Last edited:
bill2654
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Viper just go over Jims Punisher build and you cant go wrong. I did my first HED last month and it worked great. I used an Eggfinder TRS for deployment and tracking so my Av-bay setup might be slightly different. Used a Top Flight 54" X-Form chute for main and worked perfect. And yes you can get a 54" X-form chute and 20' of 7/16" Kevlar shock cord in the nose cone. I also got a tip from Jason Griffon at Airfest and I put my main charge in the tip of the nose cone. I'm sure a charge on the bulkhead works perfectly fine but I want that laundry to get blown out of the NC and not pulled out.
ChrisAttebery
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I have 24oz of lead, a 12"x12" nomex blanket, 20' of 1/4" kevlar and a 60" Ultra X with the flat braided lines stuffed into the 3" NC on my Saab. I recessed the forward altimeter bay lid 2" into the coupler so that it would all fit. It would easier to replace the chute with an Iris Ultra, but I can make it all fit with a little work.
Oberon
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Possibly dumb question, but unless you're using motor backup for apogee ejection, is there a good reason to put the main in the nosecone rather than the drogue? Seems like it would be easier to stuff the big chute in the main body and just use the cone for the smaller drogue.
Motor backup is a nice free backup! Saved my friend's Punisher rocket this past weekend when the altimeter failed to fire both charges. You can put main in the body, but then it will deploy at apogee (unless you remove the motor charge and rely on altimeter) and drift much farther than drogue first.
Viperfixr
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That's exactly been one of my concerns. Every time I have tried to pull out a chute, I have had limited success, like 50% success. Blowing out the chute in the direction it must go to deploy has worked every time. I was also thinking about a glove finger-tip charge taped to the nose tip for this very reason, but I was curious was the successful HED users would say.
I am rebuilding a crash-damaged 5" Gizmo (early HED-like attempt led to a no-chute landing) and converting it to HED with a new, FW nosecone. I am mirroring CJ's technique as much as I can. I've read it before, but I still do not have a good feel for getting the chute out with av-bay located ejection charges. Seems like those charges would mash the chute into the nosecone, but obviously folks are having a lot of success with it.
CzTeacherMan
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I've had zero problem getting the chute out with charges located at the av bay. It's all in how you load the shock cord... Shock cord goes in the NC tip, chute after. That way, for the NC to separate from the body at all, the chute necessarily must come out too. The BP charge doesn't "mash" anything. It's not a hydraulic piston... A BP explosion is nothing more than rapidly expanding gases. So it's only "pushing" against other gases in the nosecone. That pressure is what separates the rocket. That rapid expansion of gas didn't "push" anything... The chute bundle comes out because it's attached to the shock cord and the cord is attached to two pieces of rocket, so as those rocket pieces separate, the cord pulls out, and viola: parachute.
Great thread. Thanks to the OP for starting it and for all the input from those with experience with HED. I want to try this for my current tube fin project, but have one major hesitation..... tracking. First, let me explain that I have no experience with any tracking of any kind. I built my Level 2 rocket with a dedicated nose cone bay for a tracker, but didn't need it for my 'low and slow' cert flight. My next goal with that rocket is to stuff a bigger motor in it to break a mile high (tracking needed). I'm waiting for the new Missle Works offering to compare GPS trackers before my first purchase. My concern with HED and tracking is having the tracker in the AV-bay with possible interference issues with threaded rods. I noted one post in this thread mentioning an EggFinder TRS. What have others done? Is my concern about interference valid?
stealth6
insert witty tagline here
In my Punisher - and in some of my other rockets - I attach my tracker to the drogue shock cord, about 2' away from where it clips to the rear AV bay lid.
I use a BRB900 GPS. What I do is wrap it first in some soft foam, then that gets wrapped in a special nomex "pocket" that I made, then I do a really health tape wrap around the whole bundle (which also fastens it to the shock cord). Works great.
s6
I use a BRB900 GPS. What I do is wrap it first in some soft foam, then that gets wrapped in a special nomex "pocket" that I made, then I do a really health tape wrap around the whole bundle (which also fastens it to the shock cord). Works great.
s6
s6, what do you do to protect the antenna? Is it included in the foam wrap and nomex pocket?
