Nose Cone Based Alt Deployment

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Theory

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I am in the early planning stages of a new build and want to work some ideas around altimeter based deployment, though not the typical "break in the middle" sort of arrangement.

The build will use a 4" airframe with a 4" Pinnacle nose cone. the Pinnacle is advertised as having a 5.75" shoulder, which after cutting and squaring the end should leave me with at least 5.5" of useable space if not more; way more than enough for a StrataLogger CF (or even a pair for redundancy) and batteries.

So, my question is, are there any tricks or issues to be concerned with when building my electronics bay into a nose cone? will airflow over the nose negatively effect vent placement? Other issues?

This arrangement will be used for apogee deployment only with a JLCR to release the main as needed. I like the clean lines that come with "head end deployment," and the benefits of altimeter based ejection over motor based ejection are without question. Just want to make sure I plan for / engineer in everything that will be needed

thank you all!
 
I have done this on several rockets in different sizes. It works just fine. I also questioned air flow issues over the static ports. On a couple the ports were drilled into the actual nose cone. While on others they were drilled through the body tube low into the shoulder. Both locations are not optimal and I believe the nose cone vents are probably worse. I believe it messes with the airspeed reading that your altimeter would give you. But it always works just fine for deployment to detect apogee.

Here are a couple nose bays that mount to a bulkhead attatched in the nose shoulder. Atterberry Performance Engineering makes a kit that doesn't even require cutting off the whole end. 0503181623b.jpeg0130191323_HDR.jpeg1002182014_HDR.jpeg
 
nice!

i had a few ideas in mind, one with a 3" airframe mounted in the nose cone allowing for a ton of room in which to mount anything i want, and a second, with the more traditional sled mounted to a "coupler CR" that would then mount to a CR epoxied (or otherwise mounted) to the nose cone's shoulder.

not so much worried about inaccurate air speed readings. this will not be a mach buster of any sort, though it will need to be strong as i anticipate flying the Aerotech H550 and I1299 motors, so there will be a very substantial G-load on the assembly.
 
I put a bay in everything I fly. And most of my rockets are on the short side so the bays go in the nose. Many ways to do it and I don't think I have done it the same way twice. MAC Performance sells a good kit to add a bay to the nose cone.
I never have any problems popping at apogee.
 
cool deal, sounds like this concept is a go

I will start drawing up some plans.

Mikey, did you dtill your vents in the nose cone itself or in the airframe and shoulder? I could see both working, thought he former would be "easier"
 
This nose has a 1/4" allthread running from the tip. The altimeter and battery mount on the bulkhead. The recovery eye nut secures it all. This it 4", any smaller would be tough to get your hand in. 0117182035a~2.jpeg
 
cool deal, sounds like this concept is a go

I will start drawing up some plans.

Mikey, did you dtill your vents in the nose cone itself or in the airframe and shoulder? I could see both working, thought he former would be "easier"

I have done both. I have four different 4" rockets with four different setups. One is 2 CRs and a sink drain pipe, 2 have bays I designed and had Wingarcher cut from plywood and one uses a MAC setup.
It's easier to put sampling ports in the cone itself but depending on sled design and the switch used, it can be a PITA to line up the switch with the access hole. There are simple solutions of course.
When going through the shoulder you just have to be mindful of the possibility that the nose cone can spin inside the airframe and close off the sampling ports. Easy ways to mitigate that too. I can elaborate later.
I have trouble typing on my phone and the network at work is really crappie this week for some reason. Finally some down time and it takes 15 minutes to load a stupid page. I'll post pics and/or designs when I get home if your interested.
 
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My instrumentation background flinches everytime I think of sampling ports that close to the front of a tube-body, but our sampling doesn't have to be instrument precise, just good enough to trigger deployment at the right times!

Key your nosecone by adhering a small section of airframe to the nosecone. Works perfectly for aligning sheer pin holes, should work just as well for vent/switch holes.
Others use little brass rod pins for keying, I just like this method because the cutout is already a perfect match for the hole :D


20180723_214320-jpg.358176
 
Pretty much all my HPR flights are with altimeter in the NC, blowing the NC off at apogee. As an example you can see the 3D printed NC here: https://forum.ausrocketry.com/viewtopic.php?f=6&t=5019

Never had any issues with strange deployment (TeleMega always used). Static port is in the NC shoulder (doubles up as RBF pin hole).

I key all sections with a little piece of composite or a steel tooling pin at the interface, as others have done. Makes alignment amazingly easy.
 
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I've been using the Public Missiles Intellicones for nosecone mounted deployment. I have 3 main sizes and just swap from rocket to rocket. Very simple concept but for the price they were just as cheap to keep using. They use an inserted payload bay that are the same size for 2.6" thru 4" and I usually just keep two complete bays and insert as I need one. Now I am simply copying the design for my fiberglass nosecones. Much simpler before I got into fiberglass.
 
Ok. Working on an idea where I would anchor a piece of all-thread in the tip of the nose cone and that would assist in anchoring a bulk plate about 1 inch forward of the end of the shoulder. This bulk plate would have a pair of t-nuts that would anchor the typical all-thread rods found in typical electronics bays. The rest would be standard fair.

I am going through all this to build a solid piece that will stand the “test of time”

As for the vents, they will be placed in the portion of the nose cone itself below the forward bulk plate

Thoughts?
 
Ok. Working on an idea where I would anchor a piece of all-thread in the tip of the nose cone and that would assist in anchoring a bulk plate about 1 inch forward of the end of the shoulder. This bulk plate would have a pair of t-nuts that would anchor the typical all-thread rods found in typical electronics bays. The rest would be standard fair.

I am going through all this to build a solid piece that will stand the “test of time”

As for the vents, they will be placed in the portion of the nose cone itself below the forward bulk plate

Thoughts?

I would start by looking at either the LOC RNWS(removable nose weight system) or Public Missiles intelicone, they both employ a similar method of anchoring a bulkheld in-place in the nose cone. No sense re-inventing the wheel. What you want is really quite simple, cut off the rounded base of the typical LOC nosecone, that will reveal a lip back where the cone enters the airframe, get the right size bulkhead either 1/4 plywood or FG, insert your t-nuts then pour some of your favorite epoxy into the inverted cone, snap the bulkhead inplace and flip over and let the epoxy bond around the edge of the cone and the bulkhead. May want to cover the open t-nut with some masking tap to avoid filling with epoxy, also add an eye bolt for securing. Just a suggestion
 
The Geoff,

curious if a simple epoxy joint is mechanically strong enough here. ive never tried it, but given everything that I have read about needed dowels to secure epoxied nose weights, I figured the anchored all-thread (using a version of the dowel method) would be required. last thing I need is for the whole assembly to come lose on ejection...
 
The Geoff,

curious if a simple epoxy joint is mechanically strong enough here. ive never tried it, but given everything that I have read about needed dowels to secure epoxied nose weights, I figured the anchored all-thread (using a version of the dowel method) would be required. last thing I need is for the whole assembly to come lose on ejection...

While not being an engineer, I trust the guys at LOC, and they wouldn't sell anything that would fail and the same goes for Public Missiles.

I just rec'd a new 4" Intellicone, I'll try and get some pics for you.
 
The dowels to secure nose weight isn't the same as using all tread to secure a bulkhead. The dowels run through the nose cone from one side to the other in a place where it will be encapsulated by the weight when it is poured into the nose cone.
A centering above the shoulder is the best way to go. Put T-Nuts in this ring and then use all thread rod as normal. Or put in a piece of bodytube and on the lower end put a stepped CR, permanently attached. That effectively sandwiches the nose cone shoulder and nothing will move.
 
yea, I understand what the dowels are for, and my thought was to use them to secure the epoxy slug to the tip of the nose cone that would also anchor the all-thread.

I am going to draw some of this out. I am a very visual person, and thanks to the 4" diameter, I can draw it all out in full scale. Time to put some ideas on paper.
 
awesome, and thank you!
IMG_20190405_101641 - Edited.jpg IMG_20190405_101743 - Edited.jpg IMG_20190405_102009 - Edited.jpg

Here are a few pics, I tried to show the fiberglass ring insert and main components. This is a 4" nosecone and the tube that carries the ebay is 14" long. To assemble you pour some epoxy into the cone then insert the tube and invert the cone so it stands on the tube until the epoxy sets. The ebay is anchored in the tube by 2 set screws that back out of the carrier, see the hole on the third pic. The odd piece of tube I fit into the carrier tube to add weight to the nosecone if needed. Hope this makes sense.
 
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