# Big Daddy nosecone Mod question

### Help Support The Rocketry Forum:

#### kcobbva

I've seen lots of threads on the Big Daddy and after a flight today and some advice about the structure of the cone, I'm considering cutting off the bottom of the nose and putting a bulkhead in the shoulder area for an even ejection plate. Best I can tell is the outer diameter of the cone shoulder is 2.9" and it's roughly .03" thick. I'm thinking a 75mm coupler with an outer diameter of 2.853" should do the trick. Anyway else already do this and have any advice? We got a poor ejection on my daughters Big Daddy today and the nomex and chute did not fully deploy. Love this rocket, so want to ensure it continues to fly and recovers properly.

Thanks.

#### rharshberger

##### Well-Known Member
Here are some of the links to various Big Daddy threads most include something about nose cone mods, a simple one is to attach a bulkhead plate to the bottom of the nose cone thats a slip fit in the airframe.

There are many more where these came from

#### rharshberger

##### Well-Known Member
I currently have a Big Daddy under construction, as we type its sitting about 3' away waiting for me to order the 1/8" kevlar for the shock cord assemble, modify the nose cone and fill the spirals and paint. I left out the motor block and will be installing a 24mm Estes screw on motor retainer, along with a nose cone Av-Bay for use with a cable cutter device and dual deploy. Fins are papered with 110lb cardstock.

#### kcobbva

...a simple one is to attach a bulkhead plate to the bottom of the nose cone thats a slip fit in the airframe
Rich...do you think the PNC-300K mentioned in those threads would be the best option with the bulkhead? I'm not opposed to swapping out and didn't think of the reduced surface area left after cutting the current nosecone.

Thanks,

kevin

#### rharshberger

##### Well-Known Member
Rich...do you think the PNC-300K mentioned in those threads would be the best option with the bulkhead? I'm not opposed to swapping out and didn't think of the reduced surface area left after cutting the current nosecone.

Thanks,

kevin
The PNC-300K is longer by 2" overall and about .5 in the shoulder iirc ( I have both NC's, the picture of the two NCs together is mine iirc) The PNC-300K does have a flatter bottom iirc. If you fly a BD with AT Hobbyline or RMS reloadable motors the standard un-modded NC isn't usually a problem since they have a fair amount more ejection oomph than Estes motors . If you install a solid bulkhead inside the nosecone ala John Coker style the nose cone shoulder will be about 1.25" long which while fairly short by HPR standards can still be reasonably friction fitted, and the shoulder will be pushed all the way clear before the ejection gasses are vented.

Last edited:

#### rharshberger

##### Well-Known Member
I plan to do the same nose cone AvBay on my BD as well.

#### rstaff3

##### Oddroc-eteer
I plan to do the same nose cone AvBay on my BD as well.
After re-reading my old post, I found that I actually stole the idea and made it my own The trick is to side the ring to so fits just past the shoulder.

#### rharshberger

##### Well-Known Member
After re-reading my old post, I found that I actually stole the idea and made it my own The trick is to side the ring to so fits just past the shoulder.
Plagerism is the best form of flattery

#### kcobbva

You guys are great. Thanks again for sharing your wisdom! Greatly appreciated.

#### rharshberger

##### Well-Known Member
You guys are great. Thanks again for sharing your wisdom! Greatly appreciated.
Wise what? Not sure but I think some one misunderstands me.....

#### Kirk G

##### Well-Known Member
I have been reading some of the comments and the Estes web site reviews for the Big Daddy.
At regular price of almost $32, it seems a little pricey for my budget. I was wondering if it ever goes on discount sales (holiday or otherwise) and what others have paid for one? #### rharshberger ##### Well-Known Member I have been reading some of the comments and the Estes web site reviews for the Big Daddy. At regular price of almost$32, it seems a little pricey for my budget.
I was wondering if it ever goes on discount sales (holiday or otherwise) and what others have paid for one?
Like the PSII (Leviathan, Scion) we may be saying goodbye to this rocket as well since the nosecone is only used on the BD, Leviathan, and Scion and Estes its looking like is dropping those kits.

#### kcobbva

Regardless of the nose issue, it's an awesome rocket. I loved my first one and my daughter loves this one. If they are consider dropping, go buy three or four and put them up for a rainy day 10 years from now. It'll be a fun rocket then too!! Also big thanks to KenECoyote who is sending me a bulkhead to attach under the nosecone. Well worth trying, before cutting or buying another nosecone. And if for some reason it doesn't eject; I can attest that it makes a really cool whistle on the way down before it crunches like my first one did!

#### Kirk G

##### Well-Known Member
I'm still not clear on what the issue with the nosecone/ bulkhead is. Can someone state is more clearly in plain english? I don't have a Big Daddy kit yet, and I'm on the fence if there's a problem...

#### rharshberger

##### Well-Known Member
I'm still not clear on what the issue with the nosecone/ bulkhead is. Can someone state is more clearly in plain english? I don't have a Big Daddy kit yet, and I'm on the fence if there's a problem...
The problem has been attributed to the large sloped area where the shock cord attachment loop is located visible on the left side of both the pictured nose cones (one on right is Estes, and sloped section is larger). With the Estes BP motors weaker ejection charges the nose cone can be pushed part way out then the ejection charge gasses escape out the opening created by the sloped section and the nose cone stops moving without the laundry deploying, the rocket then noses over and becomes a lawn dart. Nose Cone on the left BTW is the PNC-300K sold by Balsa Machining, Mercury Engineering, and Apogee. The solution many people have found is to cut the sloped section off (which also removes the shock cord loop) and to fit a bulkhead inside the nose cone just above the shoulder with a eyebolt. A properly sized bulkhead can be inserted sideways through the shoulder (maybe with a little squeeze to oblong the opening) then the bulkhead once past the shoulder can be turned and fits snugly above the shoulder (see John Cokers video on nose cone mods) the bulkhead is epoxied in place. The shoulder is shortened to about 1.125" long by the removal of the sloped section, however the nose cone once it is pushed by the ejection charge far enough that the gasses escape is now out of the rocket, not just halfway out. The problem doesn't seem to appear as frequently with the larger ejection charges from the reloadable APCP and SU motors. Another mod I am considering is a Nose Cone av-bay for a TRS and Cable cutter so I can DD my BigDaddy when flown on CTI and AeroTech 24mm motors.

Link to John Coker's Plastic Nose Cone Mods video (a bulkhead can be used in place of the centering ring if no Av-Bay is desired). http://www.jcrocket.com/plastic-nose-mods.shtml

Last edited:

#### Kirk G

##### Well-Known Member
Thank you. Do both nosecones pictured above (Estes and the PNC-300K) experience the same problem?
And where is this bulkhead then placed? Flat against the bottom of the nosecone?

#### rharshberger

##### Well-Known Member
Thank you. Do both nosecones pictured above (Estes and the PNC-300K) experience the same problem?
And where is this bulkhead then placed? Flat against the bottom of the nosecone?
I have yet to use the PNC-300K for anything but its similar to the Estes ones shoulder, though the sloped section is quite a bit shorter, so it may be less likely to happen. The bulkhead is placed inside the area just above the shoulder (there is a lip just above the shoulder where the nose cone increases in diameter to match the airframe). Below is a picture of another 3" nose cone (Pinnacle), with a centering ring for a nose electronics bay installed in the same location, I could just as easily have put a bulkhead in instead of the CR.

Last edited:

#### KenECoyote

##### Well-Known Member
TRF Supporter
A while ago I had suggested a possible simple fix is to just place a flat disk bulkhead onto the bottom of the nose cone so the sloped area is basically blocked and the nose cone is now like a regular one or even a bit like a piston. I haven't been able to try it, but I've made two for kcobbva to try and it's up to him if he wants to mount on the bottom (which is the simpler solution) or cut off the cone bottom and put inside (which is harder, but buys you more space for the chute).

Rich - Your mod looks great!

#### rharshberger

##### Well-Known Member
A while ago I had suggested a possible simple fix is to just place a flat disk bulkhead onto the bottom of the nose cone so the sloped area is basically blocked and the nose cone is now like a regular one or even a bit like a piston. I haven't been able to try it, but I've made two for kcobbva to try and it's up to him if he wants to mount on the bottom (which is the simpler solution) or cut off the cone bottom and put inside (which is harder, but buys you more space for the chute).

Rich - Your mod looks great!
Thanks, I usually take the more complex route, someday I may fly my BigDaddy on the longest CTI motor that will fit, or make a donut bay for the NC and fly the even longer ones they supposedly are working on (7G 24mm, or the 8G thats been hinted at). I have a fairly well set up wood shop (no CNC stuff yet) so I make all my own centering rings, fins, bulkheads, it also allows me to slot CRs so TTW fins self jig and interlock with the CRs. I have a BigDaddy under construction right now and it will receive the NC electronics bay, and the stock fins have been papered with 110lb cardstock (they are very stiff), the CRs for the MMT have been replaced with 1/8" baltic birch ply ones, and a Estes 24mm motor retainer has been added, so this BD will never probably get of the rod on a Estes D motor, as its a little heavy. The BD is on hold until I get my L3 paperwork completed and the L3 rocket built.

#### kcobbva

A while ago I had suggested a possible simple fix is to just place a flat disk bulkhead onto the bottom of the nose cone so the sloped area is basically blocked and the nose cone is now like a regular one or even a bit like a piston. I haven't been able to try it, but I've made two for kcobbva to try and it's up to him if he wants to mount on the bottom (which is the simpler solution) or cut off the cone bottom and put inside (which is harder, but buys you more space for the chute).

Rich - Your mod looks great!
Thanks Ken! I'm going to do just that with the big daddy and give it a try. I'll post back once we've finished and launched and see what happens.

#### kcobbva

I have a fairly well set up wood shop (no CNC stuff yet) so I make all my own centering rings, fins, bulkheads, it also allows me to slot CRs so TTW fins self jig and interlock with the CRs.
I'm Jealous!

#### rharshberger

##### Well-Known Member
I'm Jealous!
For rocketry the best tools in a wood shop are a 4" belt/6"disc combo sander (HomeDepot Ryobi $120) final OD on centering rings and fin airfoiling, a Scroll Saw (OD on centering rings), a bench top drill press for drilling/cutting IDs on centering rings, a power miter saw (cutting all kinds of stuff and cutting tubes squarely), a router and tablesaw are nice to have, and a bandsaw is nice too. I probably use the first 3 tools for 90% of my rocketry work. I do have jigs that fit the saws and sanders that allow me to cut circles, and final sand the ODs to a perfect fit inside the tube. For IDs on CRs I use 3/4", 1", 1-1/8" forstner bits for (18mm, 24mm, 29mm motor mount tubes, 29mm requires a little inside sanding to get MMT tube to fit, an 1-3/16" bit would be perfect), for 38mm to 98mm I use the adjustable circle cutter from General Tools (also called a fly cutter, the one on the right side in 3rd photo, the one on left is Harbor Freight and is not only cheap but sloppy,and cuts poorly). My preferred blade in the scroll saw is a spiral cut blade. For the cost of a 1/2 dozen MPR/HPR kits all these tools are easily had, and worth every penny. The router is very useful when paired with special jigs that allow me to do all kinds of things, but not really necessary. A set of sanding drums for the drill press is also very useful when having to slightly enlarge motor mount CR IDs. For a long time I used a Harbor Freight disc/belt combo sander (on sale for$58 currently) and a HarborFreight Scroll Saw. Be wary of the circle cutters to keep fingers and hands well clear.

#### Attachments

• 80.5 KB Views: 147

#### kcobbva

Rich,
Very nice! I have most of those, I just have no SPACE and have to drag everything out into the yard to do anything. My table saw is a PITA to get out of the shed outside. I need a sander but don't know where to put it, and I would LOVE to find a router with a dial capability verse two cinch nuts, but those are pretty expensive. I'd really love to have a planer and joiner but again space. Keep posting those jig pictures and Ideas and I'll learn from them. When time comes, I will be following your suggestions and probably asking for advice!

#### kcobbva

Ok so using KenECoyote's bulkheads, I epoxied a nut to a washer just larger than the hole in the bottom of the nosecone

Then I used a dremel to make a slit which the washer would fit through with the screw attached:

I wedged some Fix-It Epoxy in there and pulled tight for a while, then eventually unscrewed the eye. After new years, I filled the back side of the bulkhead with Rocketpoxy and filled the hole, then screwed the plate down.

Hopefully this will hold and work. Worse case, I'll cut the nosecone at the attachment and then internally mount the second bulkhead and eyebolt. Maybe if the weather holds we can try it this weekend.

#### KenECoyote

##### Well-Known Member
TRF Supporter
Wow! very clever! I had mentioned making a hole on the side of the shoulder, but I always felt that made it look a bit odd and I don't like big holes on the sides of my rocket parts, so this is a great idea to get around that and also very strong too! :clap:

BTW - Make sure the bulkhead comes out clean and doesn't hang on the sides and I think you're golden...or pink. :wink:

#### rharshberger

##### Well-Known Member
Nice retrofit! Let us know how it works.