Nike-Nike Smoke Build Thread

It's been a while since I posted so I thought I would do a quick build thread on my Plaster Blaster project. I built a 5.5 inch Polecat Nike Smoke with a 75mm motor mount and after successfully flying it on a L1420R

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I decided I couldn't leave well enough alone so I got another kit (sans nose cone) and am now building a NIKE-NIKE Smoke. Both booster and sustainer will have 75mm motor mounts. I plan on flying it on a M1550R staging to the new M650 long burn motor. Should be spectacular one way or the other...

Anyway here goes.

Interstage coupler. In order to keep the scale appearance I used the components from a dual deploy kit with two couplers in the dual deploy section that normally would have the altimeter bay. Since the interstage coupler seems to be a common point of failure I wanted the couplers to be stiff as possible so I put two wraps of 12.5 oz carbon cloth in each and put two bulkheads between the couplers.

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One half is the altimeter bay for the booster and the other half is the receiver for the sustainer. The altimeter bay is the typical polecat design....love those laser cut parts.

Here's the bay put together -

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Next is the motor tube. Four centering rings to give it the stiffness I need just in case I decide to fly a higher thrust motor. I prefer to have the staging and ignition electronics in the sustainer so it's self contained so you can see the wiring.

Booster separation and sustainer ignition will be via remote control to give some measure of safety.

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Quality of the kits are very high so assembly is pretty much a snap. I put in the motor tube and fins and that completes a half a days work.

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I let the sustainer motor hang out the back three inches in order to save the rear of the rocket from being cooked by a 9.5 second M class burn.

Booster will be a single deploy while the sustainer will be dual deploy (both with rocket hunters of course.)

I'll post more as I get time to work on it. I do plan on tip to tip carbon on the fins to ensure they don't flutter since it should make it through mach.

cheers

Mike

NICE!

Ben

Cool. Can't wait to see the flight, that's going to be awesome.

Beautiful.

Should be an awesome flight.

Good luck!

Ethan

<"Since the interstage coupler seems to be a common point of failure I wanted the couplers to be stiff as possible ...>"
-------------------------------------------------------------------------

Yeah, ...I guess you could say that.

If you have seen these pictures before, then I need not say anything...
They speak for themselves.

https://www.vahpr.com/rockets/nike/n3pics/dsc_0571.jpg
https://www.vahpr.com/rockets/nike/n3pics/dsc_0570.jpg
https://www.vahpr.com/rockets/nike/n3pics/dsc_0569.jpg
https://www.vahpr.com/rockets/nike/n3pics/dsc_0573.jpg

https://www.vahpr.com/rockets/nike/n3pics/dsc_0514.jpg

MaxQ said:

<"Since the interstage coupler seems to be a common point of failure I wanted the couplers to be stiff as possible ...>"
-------------------------------------------------------------------------

Yeah, ...I guess you could say that.

If you have seen these pictures before, then I need not say anything...
They speak for themselves.

https://www.vahpr.com/rockets/nike/n3pics/dsc_0571.jpg
https://www.vahpr.com/rockets/nike/n3pics/dsc_0570.jpg
https://www.vahpr.com/rockets/nike/n3pics/dsc_0569.jpg
https://www.vahpr.com/rockets/nike/n3pics/dsc_0573.jpg

https://www.vahpr.com/rockets/nike/n3pics/dsc_0514.jpg

Click to expand...

How did that happen?

Awesome project Mike! I'll look forward to seeing this! Any idea which day you plan on flying it?

bguff said:

How did that happen?

Click to expand...

It was called "Go Fever" on the website...a good read.

I was there at that launch, and looking at all that threaded rod, bent like it was from aerodynamic stresses (and not a CATO) - left an indelible impression.

Haven't quite looked at HPR the same since.

SpartaChris said:

Awesome project Mike! I'll look forward to seeing this! Any idea which day you plan on flying it?

Click to expand...

It all depends on what jobs I end up doing at the launch. I would guess either Friday or Saturday though. I also have a cluster project that has flown once already that i want to launch.

Mike

Well, I got a little more time to work on the rocket in the last day or so. It's nice to be able to be leisurely about a build for a change. Still have two months before I plan on launching this one.

Yesterday I built the fillets out of West Fast and Kevlar pulp...pretty much just mix it up to the "peanut butter" stage and put it in between the tape lines and smooth as best I can. Once that firms up the fins are quite stable on the rocket.

Today, I ground the fillets relatively smooth with a dremel and then filled the gouges with epoxy mixed with microballoons to make them smooth. While that was still tacky, I put the first fillet reinforcement on. A two inch strip of 5.7 oz carbon cloth....

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This should keep the fillets from cracking and begin the reinforcement process. I'm building the fins pretty stout since the rocket will probably spend a good bit of time in the transonic range. I doubt the motors will go much above mach.

Next, I put on a layer of 12.7 oz carbon on the fins. I want the fins pretty stiff so there are no issues with flutter.

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Next will come a tip to tip layer of 5.7 oz cloth and it should be pretty much bullet proof. I don't have time today to do the tip to tip layer, I know a chemical bond would be stronger but I'll just have to settle for a good scuffing for a mechanical bond for the tip to tip layer

This is one of the few rockets that I used foam in the fin can. Although I think the fin mounting technique is plenty strong enough, the cardboard body tube is somewhat flexible and I don't want flutter. A couple of layers of carbon would take care of that but a better solution was to fill the fin can with foam which stiffened up the fin can considerably without the cost of extra tip to tip layers of carbon cloth.

I did some measuring and I believe the first flight will have to be a M1297 staging to a M650.....all depends on how tightly I can pack the parachute for the booster stage.

smurf said:

It all depends on what jobs I end up doing at the launch. I would guess either Friday or Saturday though. I also have a cluster project that has flown once already that i want to launch.

Mike

Click to expand...

I vote Sat. since I'll be there! =)

can you post a few picturs of the insterstage coupler? How exactly are you doing that?

Ben

No problem, I'll post when I get off work. It's pretty simple, the rear centering ring on the sustainer is 5.5 inches (1 caliber) recessed into the body. Fin tabs have to be modified accordingly and you'll need good surface mount technique for your fins since the TTW part is greatly reduced.

The interstage coupler itself is a section of body tube (in this case 10 inches to keep the scale like appearance) with two couplers in it each sticking out about 1 caliber of each end. There's a bulkhead between them to provide the forward bulkhead of the altimeter bay for the booster (which otherwise is the standard Polecat altimeter bay).

Rear of the interstage coupler fits into the front of the booster with a tight friction fit and shear pins. Sustainer is a very tight friction fit on the top of the interstage coupler. It will use active separation of the booster (probably about .5g black powder and then the booster will ignite by remote control. I personally like to have all the sustainer ignition components in the sustainter itself but you could have the ignition bits and pieces in the interstage coupler like PML does. They use ignition of the sustainer to separate the stages (but that risks drag separation causing the sustainer to not ignite.)

I wanted to get beyond the simple timer for ignition since having an M650 go off in an undesired orientation is well....undesirable. Remote control ignition allows me to choose whether or not to ignite the sustainer or let it coast to apogee if the flight is not going well.

Most of the 2 stage rockets I've seen fail separate at the interstage coupler. Some guys use rods etc. to reinforce the joint. I feel that with a proper fit and significant strengthening of the couplers it should be just fine (I fly rockets with couplers all the time so this should be no different). I put two layers of 12.7 oz carbon cloth in the couplers and I can literally stand on them.

I achieve the friction fit the way I want it by painting epoxy on the outside of the coupler and the inside of the body tube and then sanding to an extremely tight fit. After that I lap them in to a perfect fit. That way you insure that the entire surface of the coupler is bearing the load instead of a strip of tape. (don't know if that is totally necessary but what the heck, it's a hobby.)

thanks. I asked about it for my Nike Apache. I am thinking about using rods and a coupler. Have the sustainer slide over rods and then recess the lower CR 1" so I can have a 1" coupler on the last part. I would double wall and FG the coupler for safe measure. I am doing this so I don't have drag seperation since its a 54mm dia bird and has literally no room for a timer bay.

Ben

Sorry, it took me a while to get around to posting these. First pic is the coupler sticking out of the inter-stage coupler. It is shiny because it is coated with epoxy. This is NOT for strength, it is so I can get a perfect fit...most of the epoxy will be sanded off (not that weight will be an issue for this rocket.)

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This is kind of an overall view with my hand for scale.

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And here is the coupler looking into the sustainer end. Mostly empty space. All the holes are sealed and a good coat of epoxy to make cleanup in the event of the motor separating the stages rather than drag or the separation charge.....

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A little closer view...

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And this view is the electronics bay end of the coupler. It will house just an altimeter for single stage recovery of the booster. (Yes it will have a tracker since it will probably go at least 5-6K.) Standard construction with a stepped bulkhead to close it off.

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I'll probably fly either a MAWD or it's high alt cousin for this one.

Here is what it looks like semi mated together. I haven't lapped them together yet so they won't fit inside each other.

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After much soul searching and some ground testing, the electronics package for the sustain is going to be changed. I found that the carbon fiber interferes with the signal for totally reliable R/C ignition. With the price of M motors and all, I dont' want a lot of staging "false starts" so I decided to go with two ARTS2 altimeters. Erik is going to modify the latch time on them so I don't have to deal with that .25 second issue. 5 amps for 1 second will fire any e-match out there. Can't beat that kind of service. If Plaster Blaster was a month later I'd fly the new ARTS3's. Lots of cool new features that proves he listens to his customers. One modified ARTS2 for separation and staging duty and one for deployment duty (don't have to deal with the whole mach and transonic issue.)

Hopefully this weekend I'll get to finish the fincan with another layer of carbon and get the airframe ready for painting.

Oh and for those of you out there that are going to ask why I don't use rods and all that for the interstage coupler....my feeling is that if a standard coupler is strong enough anywhere else on your rocket then this method is good enough for an interstage coupler......If your flight profile folds this then even if it were "bullet proof" another coupler would have failed and this is stronger than the other couplers in the rocket......Comments?

For those of you out there that are attending Plaster Blaster, we need RSO's and LCO's. The website has all the details www.plasterblaster.com.

If you have your level 2 or 3 you can be either an RSO or LCO. Great way to get involved in a major launch and help put together something that is worthwhile. If you are level 1 you can still help out and make a difference by being an assistant RSO or LCO. Much fun to be had and the chance to interact with others and especially those who launch the "big ones." Great way to make new friends.

Thank you! The clears some up. I decided to use a coupler instad of rods. To me there is more coverage with a coupler. I could only use 1/4" rods and 4 of those hold up a 3lb sustainer with an L in the booster! I would rather use a coupler. So I double walled a 2.6" coupler and glassed it with 2 layers of fine weave 2oz. Strong as hell!

Ben

smurf said:

After much soul searching and some ground testing, the electronics package for the sustain is going to be changed. I found that the carbon fiber interferes with the signal for totally reliable R/C ignition.

Click to expand...

Mike, I've been looking too for a more reliable way to do two-stage ignition. In particular, I wanted a way to prevent the sustainer from firing if the rocket is going off at an angle, or if something bad happens during the boost. What I've come up with is a simple transistor switch that is connected to an MC2 and a perfectflight timer. The circuit is diagrammed below.

The timer circuit is the thing that actually lights the sustainer. However, there is a simple transistor switch in the circuit that has to be energized in order to complete the circuit (a mechanical relay could also be used, but I don't think mechanical relays are good things in rockets). The MC2 has a channel that fires at a specified altitude on ascent (the RDAS has this feature also). If the rocket reaches the specified altitude by the time the timer fires, than the sustainer will light. But if the flight isn't reasonably normal, it won't light. At least, that's the plan.

I've tested this approach to death, but the first actual flight will be this weekend. Note that, as you might expect, there are some issues using the MC2 for this purpose. I have been working with Larry on this and I currently have an updated version of the firmware (I don't recommend this with the stock MC2).

Mike, I don't know if you would even have time to try this, or if you have either of the altimeters with the "on ascent" feature, but I thought I would pass along my approach.

View attachment Circuit.GIF

Jim,

that's an interesting circuit. I assume that the transistor switch remains closed once it's activated (i.e. you don't have to match up the latch times of the altimeter and the timer.)

I won't have time to build and test something like that unfortunately. The other idea that was put forward to me was to use a MAD to set the arm conditions....I'm still thinking about that one. (I.e. firing circuit remains closed as long as the rocket is within xx degrees of vertical).

I'm still thinking on this.

Mike

smurf said:

Jim,

that's an interesting circuit. I assume that the transistor switch remains closed once it's activated (i.e. you don't have to match up the latch times of the altimeter and the timer.)

I won't have time to build and test something like that unfortunately. The other idea that was put forward to me was to use a MAD to set the arm conditions....I'm still thinking about that one. (I.e. firing circuit remains closed as long as the rocket is within xx degrees of vertical).

I'm still thinking on this.

Mike

Click to expand...

The transitor switch goes on at a preset altitude, which is calculated from a flight simulation (something like 80&#37; of the altitude it would be expected to reach at a time equal to the end of the one-second timer latch time). If the rocket goes off at an angle, and then gets to that altitude late, it won't overlap with the timer, and it won't fire the sustainer. The transistor switch turns off at a preset higher altitude, but the exact value doesn't matter.

As an example, for my test flight, the rocket should be at altitudes of 1500 and 1800 feet over the latch time of the timer. The MC2 is set to turn on at 1200 feet and off at 2400 feet. So, if it gets to 1200 feet by the time it's supposed to get to 1800 feet, it will fire. Clear as mud?

One thing G-wiz is doing is modifying the firmware. The altitude on ascent setting is limited to 2500 feet. My planned flight at Balls will stage much higher than that, so they've modified this so that the altitude on ascent could be up to 25K.

I was initially considering using a MAD to trigger the transistor switch, but I couldn't come up with an equipment configuration that would work.

Jim,

I was thinking maybe a latching SCR, FET, or other type circuit so once triggered by the flight comptuer, it would stay latched?

I have a chance to work on the rocket again today. I hit it with 60 grit to knock off the high spots and give the epoxy something to bite into and started the tip to tip lamination of the fins. Basically it's one layer of 5.7 oz twill carbon. Once these cure to the leather stage, I'll trim them and do the remaining fins. Should be pretty stiff and flutter free at the speeds I'll be flying this rocket. It sims supersonic but we'll see.

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man this is cool!

And here it is all trimmed up. The epoxy is still green but I can't flex the fins even a little bit now. Once the epoxy is cured I'm sure I'll be able to fly this thing with confidence. (Well, at least the fins won't flutter.)

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That thing looks rock solid! Way cool!

In between doing fun things with the family I managed to get a little more work done on the rocket.

I took 80 grit paper and knocked down the high spots. Next I made a nice filler from epoxy and microballoons. I filled the fillets to they will be smooth and look good. An hour in the curing oven and they were ready to be shaped.

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Next I cleaned it up and painted on a coat of epoxy ammended with microballoons. I thicken it just enough so that it will barely paint on with a brush. Easy to sand and it fills really well. Most of it will be sanded off so there is little weight added.

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Tomorrow a few minutes with some sand paper and it'll nice and smooth.

Well, with the weather what it's been here lately, it was more like wet sanding with all the sweat.

I knocked off the high spots with 80 grit and then sanded with 100 grit to get it smooth. You can see that most of the filler came off.

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and another view

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it came out pretty darned smooth with just one coat of the filler so I'll prime it to find how many pinholes I missed. The quality of the fiberglassing from Polecat is pretty good so it came out well and should only need a couple coats of primer to be acceptable.

Here it is after two coats of Kilz, the interstage coupler is stacked on top of the sustainer...

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and in this one you can see how good the fillets came out. Just need a little detail shaping on the front and they are complete and look great.

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Overall I was satisfied with the fill job. Only a handful of small pinholes so a little elmers fill and sand and it will be ready to paint after this coat of primer is sanded off and one more applied and sanded with 150 and then 220.

I'll probably let the primer set for a couple of days before I sand it....I find if I give it at least 48-72 hours it sands a lot easier and doesn't clog the sand paper nearly as bad.

That's some awesome work right there. I'm itching to see some flight pics in the future.

man that is cool!!

Ben

It's looking real fine.

It's interesting that we independently came to similar designs on the coupler. I've added a LOC "Stiffy" tube in the center of the two coupler tubes to provide both added strength and a resting point for the bulkheads.

QUESTION: How are you separating? I spoke to an experienced 2-stager and explained I was thinking of using BP in an upward charge to separate. He pointed out that could ignite the motor and that I should use RouseTech CO-2.

Thoughts?

I'll use somewhere around .75g of black powder to separate the stages, exact amount will depend on ground testing. I've done it and seen it done many times with no issues igniting the sustainer (even if it did it wouldn't be that big of a problem except for giving up a minor bit of altitude.) I'll have the plastic cap over the nozzle anyway so I doubt there will be a problem. My separation charge will be initiated by an ARTS2 set for .5 seconds after burnout. The other pyro channel on the ARTS2 will ignite the sustainer about 4 seconds after burnout. I plan on using a piece of surgical tubing to contain the bp (I've been using this method ever since I saw it on Tfishes website without a single failure) which keeps everything neat (also the charge will be tucked up in the sustainer cavity reducing the chance of a spark travelling 28 inches up the motor to ignite the bp (or thermite) ignitor.


I thought about the whole rod and receiver method but my thoughts is that if a coupler is sufficient anywhere else on the rocket then it should be good enough for the interstage coupler. I can literally stand on the coupler so there should be no issues although I am always open to suggestions or comments.