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  1. #1
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    Question Launch Pad's 2-Stage Nike Hercules

    Has anyone built the Nike Hercules rocket based on The Launch Pad's kit plans with the electric 2nd stage ignition system? I know some have built this rocket from a kit that's no longer in production, but as I understand it the kit is a single stage rocket.

    I'm slowly building this rocket now from the kit plans being sold on eBay and I'd like to discuss a few things with others who have, or are, build the 2-stage rocket from those plans...

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  2. #2
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    About 20 years ago I built The Launch Pad's two-stage Standard Missile (plan pack for the first stage). It used a pressure switch to ignite the second stage, which I don't recommend. Also, the first stage was under-powered as built. I knew that they had a Nike Hercules that was single stage powered. I did not know that they had a two-stage Nike Hercules.

    OK, I just looked at my records. I do have a plan pack for the Nike Hercules and it does have the pressure switch in the booster for igniting the second stage. Is this what you have?

    Last edited by aerostadt; 31st October 2017 at 06:58 PM.

  3. #3
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    It was a plan pack and used the same ignition system as the Standard- 4x24mm cluster in the booster, with 3XD12-3 and a D12-0 in a sliding mount that pushed on a normally open momentary switch when thrusting and then closed the circuit when it moved back.

    kj

  4. #4
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    Quote Originally Posted by aerostadt View Post
    ..Also, the first stage was under-powered as built. I knew that they had a Nike Hercules that was single stage powered. I did not know that they had a two-stage Nike Hercules. OK, I just looked at my records. I do have a plan pack for the Nike Hercules and it does have the pressure switch in the booster for igniting the second stage. Is this what you have?
    Yes, that is what I have - they refer to it as a "piston".

    I would also agree that the booster stage is under powered. I have been modeling their design in Rocksim as I build the rocket Even though I've taken measures to reduce weight in the stage (like not using booster tube couplers), I'm finding the 4 D-12 booster motors and a D12 2nd stage only gets to ~900 ft with margin just over 1 - and that's with ~50g of nose weight. I have made one design change that lengthens the 2nd stage MMT to allow for an E motor.

    But I am concerned that the piston switch may eventually stick. Their design relies on that motor ejecting out of the MMT. I assume its possible even though a D12-0 has no ejection charge. Th friction fit of that motor appears to be critical but the "plan" offers no guidance about motors or their installation expect to say only use a D12-3 in the recovery (parachute) booster tube.

    This design has the booster using 3 D12-0s and one D12-3 (to eject the booster parachute). Three of the four booster MMTs are closed at the fwd end.

    IMO this "plan pack" was poorly written, and there are no templates - only not to scale drawings. It is not for the inexperienced rocketeer...
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  5. #5
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    Ah my fuzzy memory had the number of -0 and -3 motors reversed.

    kj

  6. #6
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    Yes, that is what I have - they refer to it as a "piston".

    I would also agree that the booster stage is under powered. I have been modeling their design in Rocksim as I build the rocket Even though I've taken measures to reduce weight in the stage (like not using booster tube couplers), I'm finding the 4 D-12 booster motors and a D12 2nd stage only gets to ~900 ft with margin just over 1 - and that's with ~50g of nose weight. I have made one design change that lengthens the 2nd stage MMT to allow for an E motor.

    But I am concerned that the piston switch may eventually stick. Their design relies on that motor ejecting out of the MMT. I assume its possible even though a D12-0 has no ejection charge. Th friction fit of that motor appears to be critical but the "plan" offers no guidance about motors or their installation expect to say only use a D12-3 in the recovery (parachute) booster tube.

    This design has the booster using 3 D12-0s and one D12-3 (to eject the booster parachute). Three of the four booster MMTs are closed at the fwd end.

    IMO this "plan pack" was poorly written, and there are no templates - only not to scale drawings. It is not for the inexperienced rocketeer...
    The two stage Standard Missile from the plan pack had the same piston ignition system. You are right about having a concern about the D12-0 being tight enough for staying forward prior to lift-off, but being able to be blown out at the end of the burn. This was exactly my concern. If you look at that type of pressure switch, only about an eighth of an inch slip backward will cause the the second stage motor to fire. In fact that is what happened to me. I was at a Club launch and took the model out to the pad and mounted it ready for launch. As soon as I turned on the switch for the second stage ignition system, it fired. I never went back to that type of system again.

  7. #7
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    Question Booster Parachute Info lacking

    As I'm getting to the end of the booster section construction I've looked for information related to that section's parachute. All I find is that a 24" chute is needed. I see nothing about that section's shock cord, it's mounting, or what to do with the two parachute tube caps that were shown to be built on sheet NH11. There's a bit more info on the 2nd stage's parachute, but zip on the booster section.

    Certainly I understand the basics involved, but I'm not assuming too much when it comes to this rocket's design plan.

    I'm beginning to think this rocket will never fly...
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  8. #8
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    Quote Originally Posted by wighty44 View Post
    As I'm getting to the end of the booster section construction I've looked for information related to that section's parachute. All I find is that a 24" chute is needed. I see nothing about that section's shock cord, it's mounting, or what to do with the two parachute tube caps that were shown to be built on sheet NH11. There's a bit more info on the 2nd stage's parachute, but zip on the booster section.

    Certainly I understand the basics involved, but I'm not assuming too much when it comes to this rocket's design plan.

    I'm beginning to think this rocket will never fly...
    The Launch Pad plan packs are not trivial to understand. I have this plan pack, but I never built this model nor have I gone through the plans in detail. I did build the two-stage Standard Missile from the plan pack years ago. Just skimming through the NH plans, I gather that you need to make many of the tubes from Manilla folder material, which I know is a challenge in itself. I have the drawings/figures separate from the instructions. I see that the instructions for the UPPER BOOSTER ASSEMBLY AND STAGE COUPLER start on page 5 with step no. 26 and go to step no. 34 on the next page. You need to go through these steps. It looks like there are many Figures involved with the booster besides Figure NH11 and it looks like to me that the booster tubes at 2" diameter are much larger diameter than the motor mount tubes, which are 1" diameter. I see that Figure NH14 shows the booster/parachute tube opposite on the diagonal from the booster/ignition tube. You need to look at steps 26-34 and the referenced figures to tease out the details to build this booster.

  9. #9
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    Quote Originally Posted by aerostadt View Post
    The Launch Pad plan packs are not trivial to understand. I have this plan pack, but I never built this model nor have I gone through the plans in detail. I did build the two-stage Standard Missile from the plan pack years ago. Just skimming through the NH plans, I gather that you need to make many of the tubes from Manilla folder material, which I know is a challenge in itself. I have the drawings/figures separate from the instructions. I see that the instructions for the UPPER BOOSTER ASSEMBLY AND STAGE COUPLER start on page 5 with step no. 26 and go to step no. 34 on the next page. You need to go through these steps. It looks like there are many Figures involved with the booster besides Figure NH11 and it looks like to me that the booster tubes at 2" diameter are much larger diameter than the motor mount tubes, which are 1" diameter. I see that Figure NH14 shows the booster/parachute tube opposite on the diagonal from the booster/ignition tube. You need to look at steps 26-34 and the referenced figures to tease out the details to build this booster.
    I think you may have misread my comments. I have completed the booster section, but I did not make-up any of the tubes except for the 3-piece stage coupler tube on page NH11.

    The only questions I have at this point relates to the booster parachute, and for that item the plans say very little. RE: my prior post
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  10. #10
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    The booster calls for one D12-0 to be placed in the booster/ignition tube and one D12-3 (A D12-5 would probably too long of a time delay) to be placed in in the parachute tube. As I recall the Standard Missile (before I modified it) had a parachute compartment right below the second stage in the transition section. I think the ignition wire for the second stage was in the annular gap of the transition section just outside of the parachute compartment tube. I don't know if your set-up is the same, but regardless you must have provisions in the booster first stage for its parachute. BTW do you the written instructions that go with the figures?

  11. #11
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    Estes teabag-style shock cord mount in the parachute compartment with 1/4" sewing elastic cord twice the length of the booster. Should work fine.

    kj

  12. #12
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    Quote Originally Posted by aerostadt View Post
    The booster calls for one D12-0 to be placed in the booster/ignition tube and one D12-3 (A D12-5 would probably too long of a time delay) to be placed in in the parachute tube. As I recall the Standard Missile (before I modified it) had a parachute compartment right below the second stage in the transition section. I think the ignition wire for the second stage was in the annular gap of the transition section just outside of the parachute compartment tube. I don't know if your set-up is the same, but regardless you must have provisions in the booster first stage for its parachute. BTW do you the written instructions that go with the figures?
    My above photo shows the BT-60 parachute (recovery) tube - 4.5" long. I also assumed the mounting for the shock cord was similar to what Estes often uses (tri-folded paper with an elastic SC). My real question is what was the purpose of making 2 caps for that tube?

    Yes I do have written instructions, but the use/purpose for those caps are not discussed anywhere in those instructions. I've already tried getting answers related to the plans from the people who sell them - no go...

    Also my Rocksim model confirms that a D12-3 is the correct choice for the booster ejection motor.
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  13. #13
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    Quote Originally Posted by kjohnson View Post
    Estes teabag-style shock cord mount in the parachute compartment with 1/4" sewing elastic cord twice the length of the booster. Should work fine.kj
    Yes, but I'm still wondering why 2 tube parachute tube caps are made. It seems like a throw-away part and the plans say nothing about them - at least my instructions don't...
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  14. #14
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    Quote Originally Posted by wighty44 View Post
    Yes, but I'm still wondering why 2 tube parachute tube caps are made. It seems like a throw-away part and the plans say nothing about them - at least my instructions don't...
    This is what I did when I built the Standard Missile Plan pack about 20 years ago. I assume that you have built everything according to the plans and that everything fits and is now in place. The tube caps are made from presentation board. As shown near the top of Fig. NH11 the caps have a 1 5/8" and 1.6" diameter. This forms a lid for the parachute tube that is inside the transition section. I put a small screw eye through about the center of the lid with the eyelet on the down side. I then put epoxy on the exposed threads on the upper side and probably on the upper part of the lid. Keep in mind that the exhaust blast from the second stage firing is going to hit the lid and the lid is going to protect the parachute. You now have an attach point to tie the shock cord or a line to the eyelet on the lid, so that you don't lose the lid. Then attach the shock cord to the inside of the parachute tube as you would on a normal model rocket. Somewhere between the shock cord/parachute tube attachment point and the tube lid eyelet put a parachute.
    Last edited by aerostadt; 7th November 2017 at 06:53 PM.

  15. #15
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    I did a gap stage scratch built worked pretty good, however I havent worked out a successful lower stage recovery.
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  16. #16
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    Quote Originally Posted by thobin View Post
    I did a gap stage scratch built worked pretty good, however I haven't worked out a successful lower stage recovery.
    What problems did you encounter?
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  17. #17
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    Quote Originally Posted by thobin View Post
    I did a gap stage scratch built worked pretty good, however I havent worked out a successful lower stage recovery.
    Ooh! Ooh! *waves hand in air excitedly*

    What I have done is to build the booster as if it were a rear ejection rocket with a forward section of stuffer tube fixed rather than a nose cone. The stage is vented as usual but with a parachute wrapped around the mmt and a shock cord to the CRs of the forward fixed stuffer. The idea is to have the backblast ignite the upper stage and the upper stage exhaust eject the rear ejection pod.

    I have a pretty good OR render of ths with my Boosted Arcas gap stager that I can post in a minute and/or I can take a picture of the real thing- whatever would help.

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  18. #18
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    Off the top of my head I think that it might be too far and a circuitous route to use gap staging on the TLP Nike Hercules. The TLP Nike Hercules might work as built. I tend to think that Chuck Brandt in his day got the Nike Hercules and the Standard Missile to work with his system. Even converted his Nike Ajax to a a two-stage model. Note that the TLP Nike Hercules uses something like a D12-3 for the chute and a D12-0 for the 2nd stage. I am wondering if a strong friction fit using masking tape was used for the D12-0 making sure it is far forward and a pinch of 4fg powder was put on top of the D12-0 would improve things.

    I converted my Standard Missile to electronic second stage ignition with the electronics in the second stage. I cut off the transition section from the TLP first stage and sealed it up and put a parachute in the first stage as shown here:

    https://www.rocketreviews.com/plans-...-morstadt.html

    I converted the Sandman's Nike Hercules to two-stage and put the electronics for second stage ignition in the first stage. I think that I may have documented the build on Rocketry Planet, which is no longer available. If you do a search here on TRF I think you can find a electronic conversion for the TLP Nike Hercules, but I am not sure that the author made any final results.

  19. #19
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    Quote Originally Posted by aerostadt View Post
    The two stage Standard Missile from the plan pack had the same piston ignition system. ...If you look at that type of pressure switch, only about an eighth of an inch slip backward will cause the the second stage motor to fire. In fact that is what happened to me. I was at a Club launch and took the model out to the pad and mounted it ready for launch. As soon as I turned on the switch for the second stage ignition system, it fired. I never went back to that type of system again.
    I also scrapped Launch Pad's 2nd stage ignition system, and installed the timed stage start circuitry shown below:
    Click image for larger version. 

Name:	NH_Ignition Sys01.jpg 
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    I only wish I had thought ahead about this issue as I would have eliminated the booster section ignition components and saved some weight there...
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  20. #20
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    Wighty44,
    That looks really good. It's been awhile, but I have used the minitimer3 for second stage ignition. The nice thing is only one battery is needed for the electronics and the ignition. I used a 9v NiCad for the minitimer. I see that you are using a 7.4v 2s Lipo. On one occasion I used four BP C11's in the Sandman Nike-Hercules and I think that it may not have had the required length of time for acceleration to trigger the minitimer3. When I used four D12's, the minitimer3 did fire the second stage. I don't know for sure if this was issue involved, but it may have been. Good luck. It is worth a try. You still need a parachute for the first stage. If everything works, you will be very happy with the results.

  21. #21
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    Quote Originally Posted by aerostadt View Post
    Wighty44,
    That looks really good. It's been awhile, but I have used the minitimer3 for second stage ignition. The nice thing is only one battery is needed for the electronics and the ignition. I used a 9v NiCad for the minitimer. I see that you are using a 7.4v 2s Lipo. On one occasion I used four BP C11's in the Sandman Nike-Hercules and I think that it may not have had the required length of time for acceleration to trigger the minitimer3. When I used four D12's, the minitimer3 did fire the second stage. I don't know for sure if this was issue involved, but it may have been. Good luck. It is worth a try. You still need a parachute for the first stage. If everything works, you will be very happy with the results.
    I didn't want to rely on the G-trigger so it was removed from the MiniTimer and I brought the leads externally to a small 2-conductor terminal block that will use a pull-out wire at liftoff. Based on the D motor burn time I set the timer to fire the 2nd stage at 1.7 sec. The RockSim file shows a very nice plot for that timing to ~1,200 ft (4 D12s & one E12-4).
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  22. #22
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    I didn't want to rely on the G-trigger so it was removed from the MiniTimer and I brought the leads externally to a small 2-conductor terminal block that will use a pull-out wire at liftoff. Based on the D motor burn time I set the timer to fire the 2nd stage at 1.7 sec. The RockSim file shows a very nice plot for that timing to ~1,200 ft (4 D12s & one E12-4).
    Sounds cool! Obviously, you have put a lot of work into this project. I would love to see some pictures of the model. I get the impression that it is fairly big.


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