Build Thread: 1/6th-Scale Nike Hercules

[JMZawodny]

I have always been fascinated with the Nike Hercules. It is just a cool, powerful looking rocket. I think most fliers agree and some have thought of actually building one. You can still find the 1/12th-Scale RoachWerks kit, but I was thinking of something a little bigger. Initially I had planned to build a 1/4-Scale NH since you can get the scale 4.1" diameter FWFG tube for the booster motors. That would have been a monster (and maybe something I'll reconsider after gaining experience with the current project). I spent a fair amount of time researching the available drawings and scale data. You quickly come across drawing by R. S. Barker, Peter Alway, or Stephen Maire - the latter being the best IMHO. None of these are fully consistent and you need to sort through the various errors. All of them appear to get the shape of the Nose Cone wrong and I'll come back to this point later in the thread. I'm fortunate to have an accessible Hercules at a local outdoor museum which I plan to use to double check my design. I want this project to be a two-stage with both the booster and sustainer having dual-deploy recovery systems. My first question was what scale to model this in. I put together some crude designs in RockSim for a 1/10th, 1/6th, 1/5th, and 1/4th scale just to see how big they were and how much room I had to work with for the recovery systems. The materials, cost of the parts, motor choices, and predicted performance were also considerations. I ended up selecting 1/6th-scale (actually 16.3%) for this project. The booster will have four 38mm motors and the sustainer a 54mm. This is going to be my summer project, except I have no idea which year that summer will be when it is done. Here are a couple of screen captures from RockSim.

 

[JMZawodny]

All the actual design work is 3D done in AutoCAD. That way I can save the 2D outlines that I need to generate the G-Code for the CNC router. I began with the design of the booster. I need to have parts to hold the motor tubes together securely, but not deviate from the scale outline. Each Nike motor has a thrust ring welded on at the top. I felt this would be a good way to transfer the motor thrust to the coupler assembly. With some good planning I was able to save material and make the centering rings for the motor mounts at the same time. Making four or eight of many parts can consume a lot of material if you don't plan the work. Here are some AutoCAD screen shots.

 

[JMZawodny]

Here are the parts cut out. This thing is going to have a lot of parts. I do not know if it will end up with more than the 92 parts in my 2.5x upscale of the Estes Black Star Voyager, but it very well could.






And then after I slotted and cut the airframes to length, I was able to test fit everything.

 

[JMZawodny]

I like my centering rings snug, so I cut them a little big and then take down the OD with my tabletop belt sander and open up the ID with a Dremel sanding drum. Only a few thousandths and they fit nicely. I'm using the slimline retainers on this project.

 

[JMZawodny]

This is now day 3 of the parts fabrication and I'm doing the Booster's fins. The scale fins have a diamond airfoil an are actually pretty hefty at 1/6th-scale. The roots will be just under 0.5" thick and the tips slightly less than 0.25". The leading and trailing edges are a small diameter. I selected 1/16th G10 sheet for the core. That will look like a 3/8" radius at full scale. My design has a 1/16th G10 central rib to define the tapering of the max width of the fin. Both the fin core and the rib are slotted so they will interlock. I had to split the root end of the rib so it would slide over the fin core. I used a very thin X-acto saw blade for that. They do not last long cutting G10 though. The body of the fin will be 1/4" balsa sheet. Here are the parts, and a pic showing how everything goes together. Now it looks more like a Nike Hercules.

 

[rocketjet787]

It looks I'm excited to see how it turns out.

 

[mikec]

This is an amazing project, I'm really looking forward to following your progress!

 

[JMZawodny]

I did a mental parts count and quickly exceeded 60 parts in just the booster (not including any metal or recovery HW or anything in the coupler section)! When it comes time to assemble all these parts, it is going to be a little bit Rubik's Cube and a little bit Jigsaw Puzzle. The sequence of assembly and painting will be critical to success. Sometimes I wish BlueTube came in olive drab.

 

[thobin]

Subscribed! op:


TA

 

[thobin]

Have you a sim on the sustainer? All by itself I know in a small BT-60 scale it was vary unstable, it took some nose weight to bring it inline. Any idea on why the total weight will be?


TA

 

[JMZawodny]

Have you a sim on the sustainer? All by itself I know in a small BT-60 scale it was vary unstable, it took some nose weight to bring it inline. Any idea on why the total weight will be?

Yes, I have simmed the sustainer by itself. I'm not happy with the results for calculating Cp. I have not invested the time to get the fins just right in the sims, but modeling them as simple fins ends up with a lot of the fin area inside the airframe. The cardboard cutout method differs a lot from either the Barrowman or RockSim methods and I suspect the reason has to do with the fin area inside the airframe. I may have to build a smaller version to test the stability at various Cg locations. I do not have a good mass estimate yet, but the current sim has it at 25 pounds without the motors. If it gets to be much over 30 pounds I'll probably reconsider increasing the booster motors to 54mm. I have not glued anything together yet, partly because I need to get a very good estimate of the weights. I'd hate to be limited to only the I800's for the booster. The total weight of the parts I've already made for the booster come to 3 lbs. 13 oz, so I'm doing OK so far.

 

[gdjsky01]

Subscribed!!! op:

NICE!!!!

 

[sandman]

You may like this one.

Almost identical but smaller.

https://www.rocketryforumarchive.com/showthread.php?t=42132&highlight=Nike+Hercules

Your centering ring and space design is identical to mine...not saying you took anything. Identical design issues usually involve identical solutions.

 

[JMZawodny]

You may like this one.

Almost identical but smaller.

https://www.rocketryforumarchive.com/showthread.php?t=42132&highlight=Nike+Hercules

Your centering ring and space design is identical to mine...not saying you took anything. Identical design issues usually involve identical solutions.

I actually own that kit, maybe I should take another look at it before I get too much further along. I have not really studied the parts since I first got it two years ago. I do seem to recall a 4-ringed laser-cut part though, but you pretty much have to have that design. Some the the implementation details are dictated by the real thing and others by engineering functionality. The lower X's are done that way so the base wrap has something to stiffen and support it. I'll be making the wrap out of 2 layers of 1/64" plywood formed and laminated together, but I'm getting ahead of myself in this build thread. I guess I should put the CD that came with the 1/12th-scale kit and look at it sometime.

I have two hundred 00-90 brass hex-head machine screws on order and plan to use most of them in the build. I'll also let the CNC router put dimples where the rivets go. Other detail parts I'll CAD up and print with the 3D printer. There are many hours of CAD work ahead of me on this one. Although this is the sort of project I really enjoy working on. I can't seem to get too enthused building another 3 or 4 fins and a nose cone rocket anymore.

 

[sandman]

The four ring laser cut part just holds the tubes together while the glue drys.

I only use 2 of the "X" spaces on my kit simply because being low power two was all you need.

High power definitely needs more.

As for the transition, I could probably make one faster out of balsa.:wink:

Once it's designed scaling in CAD is easy.

That's why I had 3 different sizes.

Actually I have made a few more different sizes in larger scales for individual.

It will take a ton of weight to balance with all those big fins on the sustainer. I was even using a lead slugs in the nose cones. like 4 or 6 oz for the 4 x 24mm kit.

Look at the pdf files for some of the larger scales. The freakin' nose cones alone get a bit "massive"!

Ya gotta love the 4 flames on boost!

BTW, what is going to power this monster?

View attachment Nike Herc parts layout.pdf

View attachment 4inherc.pdf

 

[bradycros]

This has to be the best looking missile ever made. Your doing very good at recreating its killer looks.

 

[bill2654]

The Hercules is one of my favorites. I scratch built a 29mm version a few years ago. I sure would love to see yours fly when it's done.

 

[rocketgeek101]

So cool! Subscribed!

 

[sandman]

Killer and as cool as the Nike Hercules is, there were some drawbacks to the concept.

The flight profile was to launch it at about an 85 degree angle where the booster would push it to 100,000'.

This would take it well above a fleet of incoming Soviet bombers.

The sustainer would orient it's XY axis pick up the radar information on the incoming bad guys, aim and fire the sustainer motor to eventually close on the bombers from above at a bit over mach 3 and detonate a nuclear warhead in the middle of the fleet.

Unfortunately, a few studies by the military relieved that a Nike Hercules detonation would result in approximately 100,000 collateral U.S. civilian deaths.

Remember, these things were station all around the U.S. at every major city.

THAT'S a big drawback!

But still a mega cool rocket!

 

[JMZawodny]

The four ring laser cut part just holds the tubes together while the glue drys.

I only use 2 of the "X" spaces on my kit simply because being low power two was all you need.

High power definitely needs more.

As for the transition, I could probably make one faster out of balsa.:wink:

Once it's designed scaling in CAD is easy.

That's why I had 3 different sizes.

Actually I have made a few more different sizes in larger scales for individual.

It will take a ton of weight to balance with all those big fins on the sustainer. I was even using a lead slugs in the nose cones. like 4 or 6 oz for the 4 x 24mm kit.

Look at the pdf files for some of the larger scales. The freakin' nose cones alone get a bit "massive"!

Ya gotta love the 4 flames on boost!

BTW, what is going to power this monster?

Those designs are reasonably close to scale, but have the usual problems with the wrong nose cone shape and the booster fin span is probably based off of Alway's drawings. I thought about doing the CAD work at full scale, but there are so many adaptations to the available tube diameters that it was a little impractical to do so. I could have used a limited set of parametric constraints, but I think this is probably the most practical scale for most fliers. The transition is pretty easy to create in AutoCAD. After that I just hit the print button and the part is finished when I get up in the morning - what could be easier. Actually, I'm going to have a lot of structure inside the inter-stage transition so a block of balsa would never work for this. Getting that structure designed was probably the hardest part of engineering the recovery system. I currently have 6 pounds of nose weight to get the sustainer to be marginally stable in the simulations. Doing a little subscale testing should allow me to refine where Cp really is and hopefully reduce the amount of nose weight required.

 

[JMZawodny]

I'm going through my stock of sheet balsa and just realized that I do not have a lot of 1/4" sheet. I was thinking that I'd just put 1/4" sheet on both side of the fins and then glue them in place between some large stone flats I have to keep them straight and true. I'm also considering making a pair of 1/16" G10 triplers to beef up the fin root. That would make the balsa step in thickness and preclude the use of the flats. If I go this route I may use a mix of sheet thicknesses to better use the balsa I have on hand and reduce the amount of sanding required to make the diamond airfoil shape. I'm probably going to sleep on this one before I make more parts or buy more balsa.

 

[terryg]

I did a couple of fun scale nike hercules and it takes a serious amount of nose weight to get them stable. I used rock sim for a rough guide and then spin tested them for a stability sanity test (not practical for your scale). One of the problems with this rocket is that it is so heavy after being balanced out with 4 engines that it can be a challenge getting enough parachute into it for a safe fight. This will be even more challenging for a two stage nike herc. There is build thread some where in the archives of a 2 stage nike herc with ap engines that had a good flight but the booster was destroyed by the sustainer ignition.

 

[Cl(VII)]

Killer and as cool as the Nike Hercules is, there were some drawbacks to the concept.

The flight profile was to launch it at about an 85 degree angle where the booster would push it to 100,000'.

This would take it well above a fleet of incoming Soviet bombers.

The sustainer would orient it's XY axis pick up the radar information on the incoming bad guys, aim and fire the sustainer motor to eventually close on the bombers from above at a bit over mach 3 and detonate a nuclear warhead in the middle of the fleet.

Unfortunately, a few studies by the military relieved that a Nike Hercules detonation would result in approximately 100,000 collateral U.S. civilian deaths.

Remember, these things were station all around the U.S. at every major city.

THAT'S a big drawback!

But still a mega cool rocket!

For some reason, this is all I could think of after reading your post.



This is an epically cool looking missile though, and I'm greatly looking forward to the build.

 

[aerostadt]

I bought Sandman's Nike Hercules and modified it for 2-stage electronic ignition with parachute recovery of both stages. I had 4 D12-3's in the first stage and one C11-3 in the second stage. I believe Sandman stated that he reduced the second stage fins slightly in order to promote stability. The kit also required a considerable amount of B-B's epoxied in the nose cone. There is a video link below found on the UROC website:

https://www.uroc.org/index.php/gallery/video-gallery/356-aksrockets/video/142-nike-hurcules-flight-2

 

[sandman]

I bought Sandman's Nike Hercules and modified it for 2-stage electronic ignition with parachute recovery of both stages. I had 4 D12-3's in the first stage and one C11-3 in the second stage. I believe Sandman stated that he reduced the second stage fins slightly in order to promote stability. The kit also required a considerable amount of B-B's epoxied in the nose cone. There is a video link below found on the UROC website:

https://www.uroc.org/index.php/gallery/video-gallery/356-aksrockets/video/142-nike-hurcules-flight-2

Well, the original Nike Hercules had a nuclear warhead in the nose.

Not the new ones! The old 1950's era warheads. Those were heavy!

 

[Brent]

Those designs are reasonably close to scale, but have the usual problems with the wrong nose cone shape and the booster fin span is probably based off of Alway's drawings. I thought about doing the CAD work at full scale, but there are so many adaptations to the available tube diameters that it was a little impractical to do so. I could have used a limited set of parametric constraints, but I think this is probably the most practical scale for most fliers. The transition is pretty easy to create in AutoCAD. After that I just hit the print button and the part is finished when I get up in the morning - what could be easier. Actually, I'm going to have a lot of structure inside the inter-stage transition so a block of balsa would never work for this. Getting that structure designed was probably the hardest part of engineering the recovery system. I currently have 6 pounds of nose weight to get the sustainer to be marginally stable in the simulations. Doing a little subscale testing should allow me to refine where Cp really is and hopefully reduce the amount of nose weight required.

Save your cad files and CNC programs. I am sure there are a few of us that would not mind buying a bare bones set of parts

 

[wfcook]

Save your cad files and CNC programs. I am sure there are a few of us that would not mind buying a bare bones set of parts

+1 on this. I Want.

 

[JMZawodny]

Save your cad files and CNC programs. I am sure there are a few of us that would not mind buying a bare bones set of parts

Being a two stage with cluster booster, I'll probably want a couple of these myself.

 

[JMZawodny]

I merged my design ideas for the coupler between the booster and the sustainer with the realities of trying to keep everything to scale. I'll now spend a couple of evenings working CAD and collecting the material feedstock. This coupler will disassemble into 1) a lower section, 2) the inner section with the top ring, and 3) the shroud. I'll need to get the 3D CAD model done to see just how much room I have for the timers and altimeters. A cursory check shows I should have plently of room for the RRC2+ I'd prefer to use. Right now I plan to use a timer to separate the stages and an altimeter for the recovery system. Two of the booster tubes will be pressurized by a common pyrotechnic for separation. The other two will house the shock cord and parachute. The sims keep the booster low enough that it will utilize single deploy. Since this coupler sets the alignment between the booster and the sustainer, it will require some accurately cut parts (really just three sections of tubing and two G10 disks). To cut larger tube squarely, I use this set up that a few of you may recognize. One change I made from the basic Coker design was to pivot the tile saw and activate it with a foot pedal (I should probably document that here on TRF). It is a nice one person operation.

 

[elchucko]

https://forums.rocketshoppe.com/showthread.php?t=1852&highlight=nike+hercules

My Sandman build