Nike Hercules Build

[wighty44]

I want to build a Nike Hercules, but Launch Pad's 47+ inch kit (LP-K022) is no longer available. Although I did purchase their kit plans, I was somewhat less than excited about how those plans describe the build and some of the materials that were specified. While the NC (PNC-80K) is no longer available Apogee has something close (p/n 20080) but it's a bit longer. Also, I'm not overly keen about placing a 9V battery in the upper airframe - yet I do like the idea of how it works to ignite the upper stage motor. Overall I see a number of challenges to this build.

My first step was to create a Rocksim file for the rocket to work out the component fits. I started with Tim Van Milligan's mini Nike Hercules file that he designed for the participants of NARCON 1998. After several modifications i came up with this version. It's shorten than Launch Pad's design because I shortened the upper airframe for 20 to 18" so that I could use a single stock BT-80 tube.



Here are a few questions I'm hoping the RTF readers can answer:
1) I'm having some difficulty believing that the ejection charge from a single D12 motor creates enough pressure to eject the NC & parachute - There's a lot of open volume in 18+ inches of BT-80 airframe. Perhaps some owners of the Nike Herc rocket can allay my concern?
2) I'd really like to see a couple of photos that show how the booster section connects to the upper stage - it appears to be a slip fit
3) A few photos of the booster section construction would also be helpful

Thanks...

 

[Nantucketdink]

I definitely don't own the rocket, but I have no problem popping nosecones in even longer lengths of BT80 tubes with Estes D engines. Well, if I put a 7 second delay and it lawn darts before the ejection, I have issues. Think of the Estes Maxi Alpha for a good example.

 

[rharshberger]

Deleted

 

[samb]

I don't have the TLP kit either. You could source some parts from the Estes Executioner. PNC-80K and two 14 inch lengths of BT-80 and a coupler. Balsa Machine Services has BT80 stock in 34 inch lengths as T80-34.

 

[rharshberger]

BMS also has the PNC-80K or a balsa equivalent.

 

[wighty44]

Thanks to all for the feedback.

 

[Rex R]

slip fit usually works, just make sure that it doesn't bind, you want the booster to fall away.
Rex

 

[wighty44]

slip fit usually works, just make sure that it doesn't bind, you want the booster to fall away.
Rex

Thank you.

By what method does your Nike-Herc separate? The plans I have call for making an electric interlock system that appears to ignite the payload stage motor when one of the booster motors ejects. That action operates a small micro switch closing the ignition circuit. The continuity between the two stages is made via a mini phono jack & plug which must separate after the motor ignites. I've used those phono jacks and they do not separate easily/smoothly so I wondering if that might create the situation where they don't separate and then you have the booster section tied to the payload during ascent. In addition it seems that the heat form the motor exhaust could easily burn the wire insulation and the plastic phono jack cover.

I'm hoping a few Nike-Herc owners might comment with their experiences on this thought...

 

[rharshberger]

I want to build a Nike Hercules, but Launch Pad's 47+ inch kit (LP-K022) is no longer available. Although I did purchase their kit plans, I was somewhat less than excited about how those plans describe the build and some of the materials that were specified. While the NC (PNC-80K) is no longer available Apogee has something close (p/n 20080) but it's a bit longer. Also, I'm not overly keen about placing a 9V battery in the upper airframe - yet I do like the idea of how it works to ignite the upper stage motor. Overall I see a number of challenges to this build.

My first step was to create a Rocksim file for the rocket to work out the component fits. I started with Tim Van Milligan's mini Nike Hercules file that he designed for the participants of NARCON 1998. After several modifications i came up with this version. It's shorten than Launch Pad's design because I shortened the upper airframe for 20 to 18" so that I could use a single stock BT-80 tube.

View attachment 330278

Here are a few questions I'm hoping the RTF readers can answer:
1) I'm having some difficulty believing that the ejection charge from a single D12 motor creates enough pressure to eject the NC & parachute - There's a lot of open volume in 18+ inches of BT-80 airframe. Perhaps some owners of the Nike Herc rocket can allay my concern?
2) I'd really like to see a couple of photos that show how the booster section connects to the upper stage - it appears to be a slip fit
3) A few photos of the booster section construction would also be helpful

Thanks...

Wighty, I have been building a Nike Hercules similar to the TLP plan pak version only slightly upscaled and modified, it is possible to source almost all the parts from BMS. I my case I used T-204 for the four booster tubes and T-300 for the sustainer (its slightly upscaled on the sustainer). My version has been modded for MPR and HPR motors along with staging electronics and deployment altimeters. IIRC the T-204 tubes will work for the standard plan pak boosters (2.0" hand rolled tubes in plan pak), and the BT-80 will work if building the PP version stock, along with the BNC/PNC-80k nosecone. My version has a turned nose cone since I have the lathe to do it. I am attaching the build thread just in case you want to check it out. One option is that instead of clustering is to use a central BT-80 airframe through the center of the booster and use the T-204 to simulate the individual motor tubes ,see my build thread, the AV bay for the booster is a T300 inside four T204 tubes, the central tube could easily have been run all the way to the rear of the booster allowing the installation of either a single motor mount like a 29mm or a cluster of 24mm motor mounts.

While I started with the plan pack version I kind of got carried away going scale like and other stuff, there is no way my version will ever fly with D-E motors.


https://tricitiesrocketeers.freeforums.net/thread/360/nike-hercules-stage-build-thread

 

[wighty44]

Rich,
Thank you for the build link and comments. I felt that this build would be a bit involved and take time. Your efforts and the results are exceptional! Well done. While I don't expect to go to that level, your build photos help to decipher the Launch Pad plans I have and offer another perspective. I'm still not overly enthusiastic about their use of a mini phono jack & plug in the payload ignition circuit.

This will certainly be a build that will go slowly and I may make modifications along the way. It looks to be the most challenging build I've yet to do...

 

[rharshberger]

When you get to the 4 in 1 transition get in touch with me, it can be much easier than it looks and my method is pretty simple, hard explain but simple.

 

[wighty44]

When you get to the 4 in 1 transition get in touch with me, it can be much easier than it looks and my method is pretty simple, hard explain but simple.

Are you referring to the booster to 2nd stage section transition? BTW, I'll be trying to build this rocket using as many commercially available tubes as possible. The one spot I see that I may need to make a few tweaks is using BT-70 tubes for the 2" booster tubes.

 

[rharshberger]

BMS has a T-204 tube that is 2.024" iirc, and its what I used. The 4 into 1 transition (interstage) is the one that goes from the tops of the four booster tubes to the upper stage.
The T-204 is the same as what Estes is using on the current Mercury Redstone, I believe it is also known as Centuri ST-20.

 

[wighty44]

BMS has a T-204 tube that is 2.024" iirc, and its what I used. The 4 into 1 transition (interstage) is the one that goes from the tops of the four booster tubes to the upper stage. The T-204 is the same as what Estes is using on the current Mercury Redstone, I believe it is also known as Centuri ST-20.

Thanks for the tip on the T-204 tube - I just ordered them.

 

[GlenP]

Ice Breakers Ice Cubes come in a neat plastic package with a roughly 2" diameter round bottom and a rounded square top, that should fit around 4x24mm engine tubes. Not sure if this would be a suitable transition for this particular rocket, the square corner radius is not right, but could be modified and used as a kind of mandrel if you wanted to paper or glass laminate your own version for some other similar scratch build. Something to consider. If properly vented, you could probably gap stage.

 

[dhbarr]

Ice Breakers Ice Cubes come in a neat plastic package with a roughly 2" diameter round bottom and a rounded square top, that should fit around 4x24mm engine tubes. Not sure if this would be a suitable transition for this particular rocket, the square corner radius is not right, but could be modified and used as a kind of mandrel if you wanted to paper or glass laminate your own version for some other similar scratch build. Something to consider. If properly vented, you could probably gap stage.

View attachment 331458

I've been eyeballing the one on my wife's desk for sinister purposes, as well.

 

[wighty44]

Ice Breakers Ice Cubes come in a neat plastic package with a roughly 2" diameter round bottom and a rounded square top, that should fit around 4x24mm engine tubes. Not sure if this would be a suitable transition for this particular rocket...

Thanks for the tip, but the T204 tubes from BMS worked quite well.

Because the tube's ODs are 0.024" greater than what the plans call for, the transitions (NH08 & 09) and the associated support tube centering rings need to be "adjusted". This adjustment took a bit of analysis and math. However, I'm getting close to finishing the booster section...

 

[rharshberger]

Looking good so far. I used Open Rocket to print the transition. Measurement for top of booster tube was taken with a long strip of paper to follow the contours of the four booster tubes marked when it wrapped back on itself then laid out flat and measured with a decimal inch ruler. The top measurement is simply the upper tube ( not that I needed to mention that), other than the bottom its pretty much a standard cardstock transition.

 

[wighty44]

Looking good so far. I used Open Rocket to print the transition. Measurement for top of booster tube was taken with a long strip of paper to follow the contours of the four booster tubes marked when it wrapped back on itself then laid out flat and measured with a decimal inch ruler. The top measurement is simply the upper tube ( not that I needed to mention that), other than the bottom its pretty much a standard card stock transition.

Thanks Rich.

I'm still uncomfortable with Launch Pad's overall design in these areas:
1) The piston actuated 2nd stage ignition design. While it is a novel notion, it appears unreliable. In another TRF topic a plan builder had his 2nd stage ignite on the pad. Also, it seems that design would become unreliable in future launches due to debris fouling the piston.

2) The Booster Stage is under powered and modeling it in Rocksim demonstrates the rocket's narrow margin which makes me pay very close attention to component and glue weights. Another design change I made to improve the margin was to not extend the booster's wrap-around base segment beyond the base of the booster tubes (plans called for a 1.25" extension). I also felt the change would provide an improve aft fin mounting foundation. Had I been aware of this before building the rocket I most likely would have extended the MMTs to accommodate E motors. It's too late now...

Building this rocket is a challenge. It requires experience, patience, and attention to detail. Not to mention exacting hobby knife skills...

 

[rharshberger]

Thanks Rich.

I'm still uncomfortable with Launch Pad's overall design in these areas:
1) The piston actuated 2nd stage ignition design. While it is a novel notion, it appears unreliable. In another TRF topic a plan builder had his 2nd stage ignite on the pad. Also, it seems that design would become unreliable in future launches due to debris fouling the piston.

2) The Booster Stage is under powered and modeling it in Rocksim demonstrates the rocket's narrow margin which makes me pay very close attention to component and glue weights. Another design change I made to improve the margin was to not extend the booster's wrap-around base segment beyond the base of the booster tubes (plans called for a 1.25" extension). I also felt the change would provide an improve aft fin mounting foundation. Had I been aware of this before building the rocket I most likely would have extended the MMTs to accommodate E motors. It's too late now...

Building this rocket is a challenge. It requires experience, patience, and attention to detail. Not to mention exacting hobby knife skills...

That's one of the fun things about rocket building, changing the design to fit our needs. Part of the reason for the extended skirt on the base might have been to get as much mass forward of the fins as possible, increase base drag, but not far enough to have issues with Krushnic Effect.

I didn't like the piston system either. Eggtimers Quantum could be used if you wanted to make a nose cone bay and then run wiring to the second stage motor to light the second stage. By using a NC bay you reduce the extra weight you would normally permanently put there.

As for the underpowered part an option is to use CTI or AT 24MM motors that will fit the normal 2.75" mmt or to use the Estes E12 (only a couple of more newtons max thrust but a little more) motors and leave them hanging out an inch (plus a much longer launch rod than 36", preferably a 8' rail), not whats intended I know but might help.

 

[GlenP]

I've been eyeballing the one on my wife's desk for sinister purposes, as well.

It could also be used the other way around as a manifold for an upscale MIRV type of rocket. One booster to four sustainers. Sorry for the tangent digression. Good work the the Nike Herc so far, looks great. Would be cool to build a set, Nike Apache, Hercules, and Zeus models... as if not enough ideas in the build pile.

https://en.m.wikipedia.org/wiki/LIM-49_Nike_Zeus#/media/File:Nike_family_01.jpg

 

[wighty44]

That's one of the fun things about rocket building, changing the design to fit our needs. Part of the reason for the extended skirt on the base might have been to get as much mass forward of the fins as possible, increase base drag, but not far enough to have issues with Krushnic Effect.

I didn't like the piston system either. Eggtimers Quantum could be used if you wanted to make a nose cone bay and then run wiring to the second stage motor to light the second stage. By using a NC bay you reduce the extra weight you would normally permanently put there.

As for the underpowered part an option is to use CTI or AT 24MM motors that will fit the normal 2.75" mmt or to use the Estes E12 (only a couple of more newtons max thrust but a little more) motors and leave them hanging out an inch (plus a much longer launch rod than 36", preferably a 8' rail), not whats intended I know but might help.

Great thoughts! Thank you. I do appreciate being able to discuss this rocket build with someone working on a similar build. Again thanks...

 

[wighty44]

...
I didn't like the piston system either. Eggtimers Quantum could be used if you wanted to make a nose cone bay and then run wiring to the second stage motor to light the second stage. By using a NC bay you reduce the extra weight you would normally permanently put there...

While I'm familiar with, and have used, dual deployment (and have the Eggfinder RX, TX, & LCD modules), I've not used the Quantum.

I'm having a bit of difficulty understanding how one would setup the Quantum to ignite the 2nd stage motor at the proper time. I assume you'd want that motor to ignite just after the booster motor's burnout and the booster separates from the 2nd stage.

What am I missing...?

 

[rharshberger]

While I'm familiar with, and have used, dual deployment (and have the Eggfinder RX, TX, & LCD modules), I've not used the Quantum.

I'm having a bit of difficulty understanding how one would setup the Quantum to ignite the 2nd stage motor at the proper time. I assume you'd want that motor to ignite just after the booster motor's burnout and the booster separates from the 2nd stage.

What am I missing...?

In my case I am actually using a Missleworks PET2+ to ignite the second stage and fire a separation charge. The Eggtimer Quantuam and the Missleworks RRC3 can both be configured in such a way (time based with baro maybe) to ignite the upper stage, Cris Erving (Eggtimer) can comment more on how his product can be used to ignite the second stage, as I have not used my Quantum for that task yet.