Dual Deploy from nosecone?

I'm curious if anyone uses their nosecone to house the altimeter to control their main's deployment?

Or

Does the need for venting prevent that space being used for that purpose?

One could use accelerometer and GPS based deployment and not even care about the venting issues. Barometric apogee though, for normal altitudes, works so well...

Electronics can be wherever you want them to be. Ditto the chutes. There have been projects which eject the nosecone shell releasing the drogue and its line, and then fire the main from a chute cannon that was under the nosecone. In this configuration, the electronics is at the base of the chute cannon.

There have been projects which house the electronics in the tip of the nosecone, and the taco'd chute in the rest of the nosecone. Deploy nosecone, and use taco'd main as a drogue. Line cut to releas the main later.

Now there is a remote available for at least one altimeter. The electronics could be in either separated part, with a remote in the other. So one could initiate events from either end at will.

There are many options. These are just a few.

Gerald

Here's a good video by John Coker

https://www.jcrocket.com/plastic-nose-mods.shtml

K'Tesh said:

I'm curious if anyone uses their nosecone to house the altimeter to control their main's deployment?

Or

Does the need for venting prevent that space being used for that purpose?

Click to expand...

I have several rockets which employ a conventional dual-deploy configuration, but with the electronics in the nose cone. Basically, I have a bulkhead in the location where the electronics bay would normally be. The apogee charge is under the bulkhead and the main charge is above it. The wires from both go through the "main" section to the nose cone, and the apogee charge wire has a breakwire just above the bulkhead. It works quite well and allows the benefits of the normal dual-deploy configuration as opposed to the all-from-one-opening methods Gerald mentioned (I use those too, but I burrito my chutes - no tacos).

With respect to the function of the electronics, you can use inertial-based electronics and not worry about venting. I have seen some pretty wild altitude data when using vent holes into the nose cone shoulder on high-speed flights. It is my belief that these could spoof some of the software-based mach lockout altimeters (although I have no way to verify this). My preference would be to use a hardware-based mach lockout altimeter in this application (i.e., an altimeter where you set the mach lockout time).

I have also done this by venting the cone into the "main" section, which normally has its own vents. This smooths out the data, but exposes the altimeter to a pressure spike and possibly ejection gases when the main charge goes off. I use a small hole at the base of the cone to minimize these problems, and it works. But, my preference now is to use vents in the shoulder with a hardware mach lockout.

Jim

Check this (simply awesome) thread from AdrianA: https://www.rocketryforum.com/showthread.php?26383-Level-3-high-performance-design-and-build-thread. Great stuff, with tons of info along these lines.

I currently have two projects in the works that will house avionics in the nose cone.

s6

Wildman has a few kits designed for this. You could always download the instructions to see how he is doing it. I believe some of his V2's use this method.

Interesting thread. MissileWorks sells a 38 mm nosecone with nosecone avbay for both RRC3 and RRC2+.

My Fat Daddy project is mounting the sled in the nose. I am made a ring that centers a 4" tube section, which becomes my electronics bay. I am using motor eject and a cable cutter. The avbay is held in place with a combination of screws through the cone into the ring and a piece of all thread embedded in the nose. I will be drilling switch and vent holes through the nose cone.

Camera is MIA at the moment, will try to upload pictures when I find it.

Check the new kit from Wildman "The Punisher".............
That should answer the "how to" question......

Teddy

While some are citing the Punisher as being an example of avionics in the nose-cone - it's not really.

Essentially, the nose-cone in the Punisher has bit of upper/payload airframe integrated into it. There is a "traditional" AV bay attached between it and the fincan/lower airframe - much the way "normal" rockets are done. The drogue goes in the usual place, and the main goes in the space created by the empty nose-cone and that small bit of integrated airframe. So the avionics are NOT in the nose-cone, but rather the main chute is. The avionics (in their bay) are still in the "traditional" place below the main.

The SMART Sled inside an Alti-Cone (Landru/Missileworks) WOULD be an example of avionics in the cone. As would Adrian's and Jim's examples. Lots of folks use the cone to house the electronics along with a Cable-Cutter to build a dual deploy rocket with only one separation point. A couple I've done are here: https://www.rocketryforum.com/showthread.php?61439-Carbon-Rascal-built, and here: https://www.rocketryforum.com/showt...er-amp-Tracking-Bay-in-Nose-Cone-Build-Thread.

It's not really all that uncommon.
s6

I did this using a Raven and a cable cutter. There's a vent hole in the nosecone that might get a little ram air pressure during flight. When the rocket it slow at apogee when the baro reading is important, the ram air pressure is negligible.

I converted my Madcow Tembo and PML Bull Pup from single deploy to a dual deploy using John Coker's method shown here https://www.jcrocket.com/plastic-nose-mods.shtml.

I also used the opportunity to experiment with some differnet deployment technologies.

The Tembo had an ARRD, very nice device and reliable if you pay attention to details, if not then avoid it. I also used a Peregrine CO2 ejection but I never got the charges correct and finally gave up after a half dozen attempts, thankfully I also had backup engine deployment in each case so the Tembo has no damage.

With the Bull Pup I used the archetype dual cable cutters with a pilot/drogue attached to the main which was ejected using a hanging charge then the main released out of the deployment modified bag. This method took a while to work out he bugs but I finally figured it out and will use it again.

Tembo with dual-deploy nosecone altimeter bay

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Tembo altimeter, tracker side shown along with eh C02 and you can see the ARRD.

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Bull pup altimeter

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Bull pup altimeter bay

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PML Bull pup with dual-deploy nosecone altimeter bay

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watheyak said:

I did this using a Raven and a cable cutter. There's a vent hole in the nosecone that might get a little ram air pressure during flight. When the rocket it slow at apogee when the baro reading is important, the ram air pressure is negligible.

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Nice work - I'm stealing a couple of ideas I see here.
s6

I did it in my Minnie Magg, See Pics in Album here
Pictures show just the connection for the cable cutter, using motor eject for initial seperation, since I have added a charge canister and made it true electronic dual deploy. First flight was on an I212 using motor eject, then an I287 on full electronics, worked flawlessly both times. The slow flight on the Smoky Sams gave me no worries about disruptive airflow around the vent holes at the base of the nose cone. I would think something faster (White Thunder or VMax) might have an adverse effect on it. So, I am satisfied with Smoky or Skidmark flights on this one.

watheyak said:

I did this using a Raven and a cable cutter. There's a vent hole in the nosecone that might get a little ram air pressure during flight. When the rocket it slow at apogee when the baro reading is important, the ram air pressure is negligible.

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Where did you put your vent holes? I really like how you did that.

Here is how I did it. Pretty close to the above post but I used a nose cone with the a threaded metal tip. I ran a threaded rod to the tip then mounted the av bay around it and shoved it into the coupler then tighten up the nuts. I can get some better pictures when I get home...https://www.rocketryforum.com/showt...is-Flynfrog-s-carbon-aero&p=739764#post739764

Thanks for all the replies... I'll get a chance to check all this out soon... I'm up to 130pages and 12K+ words for my final report (so far).

K'Tesh said:

Thanks for all the replies... I'll get a chance to check all this out soon... I'm up to 130pages and 12K+ words for my final report (so far).

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WOW. Good luck.

Finished it... Final Count 135 pages (x2 (Required to make a 2nd copy)), 13,436 words, 22.3MB, 14 lesson plans, 86 pages of Appendices, and $6.99 to bind it/copy.

dgreger said:

I did it in my Minnie Magg, See Pics in Album here
Pictures show just the connection for the cable cutter, using motor eject for initial seperation, since I have added a charge canister and made it true electronic dual deploy. First flight was on an I212 using motor eject, then an I287 on full electronics, worked flawlessly both times. The slow flight on the Smoky Sams gave me no worries about disruptive airflow around the vent holes at the base of the nose cone. I would think something faster (White Thunder or VMax) might have an adverse effect on it. So, I am satisfied with Smoky or Skidmark flights on this one.

Click to expand...

Thanks for posting the link to your Martin Magg album.

I'd briefly seen the pictures before but now that I'm working on a nose cone alt bay for my Polecat Aerospace 5.5 Goblin they are enlightening. The "reverse" y-harness was a great idea!

My question is whether you epoxied the bulkhead to the nosecone when everything was ready to be finally assembled. I see your screw blocks on the backside of the bulkhead and the screws through the nose cone shoulder but there was no picture showing the bulkhead epoxied to the nose cone. Did you leave the bulkhead removeable?

Inquiring minds want to know.

Kit, yes I left it removable. It actually fits tight enough I am not worried about air/pressure leaking. Teddy at OneBadHawk made the harness, it is really nice. He does awesome work!

watheyak said:

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How did you do the eyelets in your little kevlar strap? That's great idea for the Raven. I want to steal it!

Great idea!

enderw88 said:

How did you do the eyelets in your little kevlar strap? That's great idea for the Raven. I want to steal it!

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I made a little mold with two posts made from K&S stainless steel rod that 4-40 washers would slide over, with a bump between the two rods to shape the strap. I sprayed on some mold release, then slid a washer on each post. Then I slid the Kevlar over the posts, then two more washers. Wet the whole thing out with Aeropoxy and clamped it.

The vent hole is just above the shoulder, on the yellow part.

watheyak said:

I made a little mold with two posts made from K&S stainless steel rod that 4-40 washers would slide over, with a bump between the two rods to shape the strap. I sprayed on some mold release, then slid a washer on each post. Then I slid the Kevlar over the posts, then two more washers. Wet the whole thing out with Aeropoxy and clamped it.

Click to expand...

Thanks. That was clever.