BT-60 Estes Nike Smoke modified for HPR

[charrington]

Hello friends,

It's been a month since my last build thread so I figured I would start another. The developments will not be as frequent as the last one as this one is not a certification and I figured I would bring you along for the ride. I plan on finishing this build over the next 3 months possibly. Anyways, I like putting big motors in small airframes and I absolutely adore the Nike smoke. I would say that the Nike smoke is my favorite sounding rocket and second favorite rocket/missile across all categories. The first being the Sprint missile. I am a little short on cash as I have another big build in the works that will be launching in Colorado in late May which I will do a build thread for of course. My buddies keep telling me to do some normal builds but I crave the altitude lol!

So here is the idea. I am taking a BT-60 Estes Nike smoke and modifying it to do a couple things:
1. Utilize a high power motor
2. Go supersonic

The plan so far is this:
I have been in contact with @REK and I am having some parts designed and 3d printed so that REK can adapt his filament winder to be able to wrap the Estes cardboard airframe in carbon fiber. I will send these to him along with the tube. For the balsa fins I plan on using the balsa wood as a core and sandwich it inside some carbon prepreg. If that doesn't work well I plan on just doing some carbon plate from dragon plate or fiberglass from Wildman for the fins.

For the nosecone, I am open to anyone's thoughts. One idea I have had is adding a metal tip by taking an aluminum nail, shoving it through so that the pointy end is sticking out of the rocket like a metal tip, adding a healthy amount of epoxy into the nose so that the back end of the nail is fully submerged (prep sanding and cleaning before obviously), and then filing the nail tip down and sanding it smooth so it looks and feels much more like a traditional aluminum tip.

Regarding the motor choices I would like everyone to pitch in and help me decide. Almost like a poll lol. I can go 38mm or 29mm. I originally planned for 29mm but 38mm would technically work. 29mm satisfies all of the requirements above but there's something really interesting that can happen if I put a Aerotech H999 in it...

Ignore the 29mm motor mount and centering rings for this sim. Its just there because I originally planned on 29mm and still kinda do. 200Gs is exciting tho... IF I do actually do the 38mm then I will need to look into probably some tip to tip composite work and also really reinforcing the nosecone in some way.

Let me know what y'all think!

 

[charrington]

Oh almost forgot. Regarding recovery, there will be a featherweight GPS on board housed in the nosecone. For altimeter I will use a raven with a charge packed in a microcentrifuge tube. It will be single deploy or a drogueless dual deploy with a tender piranha cutter.

 

[charrington]

Ill upload some photos of the kit tomorrow and CAD drawings/parts as I get them!

 

[ep29030]

Put a 29mm motor tube inside, and run it up to just touch the bottom of the nosecone, so the nosecone's forces are transferred to both the airframe and the motor tube. And if you put 3-4 centering rings in there (or fill the void with 2 part foam), you will effectively double-wall the rocket, giving it multiple times the strength it has out of the box. I did this to an old Quest Nike Smoke I had years ago and I flew it several times on F20 Aerotech motors. Other than the motor tube inside, the airframe, nosecone and fins were stock. I used a 6" wide mylar streamer for recovery (and visibility in the sky).

 

[Handeman]

I could be wrong, but I believe the aluminum tip on fiberglass nose cones has nothing to do with strength. It is used because the fiberglass winders can't wind the glass to a tip. They have to stop as some larger diameter and the aluminum tip was just good way to add a tip to the nose cone. You can find some nosecones that have a fiberglass tip added to them instead of the aluminum.

Adding a nail and epoxy to the tip of your rocket won't help the airworthiness of the nose cone, although it might help with landing and transport.

Use expanding foam in the nose cone to strengthen it. That will add a lot more strength then just doing the tip.

I would also put a 38mm motor in it if you really want to get supersonic. It might be hard to do with 29mm. An I1299N might be a fun load.

Good Luck.

 

[charrington]

I could be wrong, but I believe the aluminum tip on fiberglass nose cones has nothing to do with strength. It is used because the fiberglass winders can't wind the glass to a tip. They have to stop as some larger diameter and the aluminum tip was just good way to add a tip to the nose cone. You can find some nosecones that have a fiberglass tip added to them instead of the aluminum.

Adding a nail and epoxy to the tip of your rocket won't help the airworthiness of the nose cone, although it might help with landing and transport.

Use expanding foam in the nose cone to strengthen it. That will add a lot more strength then just doing the tip.

I would also put a 38mm motor in it if you really want to get supersonic. It might be hard to do with 29mm. An I1299N might be a fun load.

Good Luck.

You know that makes a lot of sense now I think about it. I think its supposed to help with the heating experienced at the tip of the rocket since that's the area with the greatest aerodynamic heating. I know that manufacturers use phenolic tips too which is what my go devil has. Phenolic being great with heat also. Do you think heating could be an issue for the plastic for this flight profile or am I just overthinking?

Here is the 1299 simd: The sim is very roughly estimated as I do not have the tube wrapped yet.


Here is another question for anyone with experience. Will the propellant hold up to G-forces like this or is there a probability of grains collapsing? Maybe @AeroTech would know.

 

[charrington]

Put a 29mm motor tube inside, and run it up to just touch the bottom of the nosecone, so the nosecone's forces are transferred to both the airframe and the motor tube. And if you put 3-4 centering rings in there (or fill the void with 2 part foam), you will effectively double-wall the rocket, giving it multiple times the strength it has out of the box. I did this to an old Quest Nike Smoke I had years ago and I flew it several times on F20 Aerotech motors. Other than the motor tube inside, the airframe, nosecone and fins were stock. I used a 6" wide mylar streamer for recovery (and visibility in the sky).

I really like this idea too. Almost like a skeleton to reinforce the airframe!

 

[Handeman]

The issue with a plastic or weak nosecone isn't so much heating on the tip or pushing back into the BT. It's the forces on the nose cone surfaces causing it to buckle, collapse, and fold in on itself.

 

[SolarYellow]

Phenolic being great with heat also.

Phenolic is a good insulator. That makes it good at keeping heat out of other areas, but if the heat builds up beyond its not-all-that-impressive temperature capability, it can crumble pretty quickly. It's an organic compound and chars.