My Madcow Rocketry 4" All Fiberglass Nike-Apache two stage modifications

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

robbdm

Rocketry Tourist
Joined
Dec 14, 2010
Messages
1,046
Reaction score
68
Location
Northern California, USA
I saw the Nike-Apache kit on pre-Black Friday sales and ordered one. I was hesitant on purchasing because of the clearance for 29 mm staging, from my build on 38 mm two stages I knew it be super tight but at $99 what the heck.

I used the long MLK holiday weekend to build. Here are my modification notes to my build so far.

Nike Apache small.jpg

Using the build instruction as a key:

NA instructions.jpg

B – replace short nose cone coupler with 5 inch one to allow for Missile Works T3 or Eggfinder mini. Only ~8 inches so small antenna needed. Plan to use Missile Works or Eggfinder sleds.
E – Using Missile Works RRC3 for staging ignition. The RRC3 is ~4 inches long. So replaced the coupler with 8 inch one to allow room. Plan to use Missile Works 29 mm sled for the RRC3 mounting.
H – notched fin roots to allow for deeper recess need for retainer. Test with your motor since clearance vary with motor.
J – cut slot centering rings to allow 3/16” break line to pass, used epoxy to seal. Shaved center rings carefully to allow clearance for break-line making sure still lined up.

photo of retainer notched

p1.jpg

I – added slight groove to make some room for 3/16” ridge break line. Used 29mm Giant Leap slim line retainer notched for access. Used 1 ½ bar of aluminum to tighten/loosen. Added a bulk head plate to seal top of coupler. Drilled hole in center of coupler, added T-Nut and ¼” threaded rod for altimeter bay. Added 1/8” inch kelvar to harness anchor.

photo of shooter wire fished into 3/16" break line

p2.jpg

photo of retainer seated with no motor

p3.jpg

photo of motor in tube without retainer

p4.jpg

photo of motor with retainer installed

p5.jpg

K – Added vent switch band. Allow inter-coupler length to allow motor and retainer
N – Plan to use Garmin DC40 for tracking and Stratogger for parachute deployment so I needed more room coupler provided. Used 6 inch one for the extra room. Added threaded rod and 4 inch bulk and air frame couplers to seal coupler. Added U ring to attached harness to booster.
O – Added rail buttons to booster section only.
Q – Added Aerotech 54mm retainer. Added 1 inch Kevlar to harness anchor.
 
Looks like fun, David. What two motors are you planning on, and what is the expected altitude?
 
I saw the Nike-Apache kit on pre-Black Friday sales and ordered one. I was hesitant on purchasing because of the clearance for 29 mm staging, from my build on 38 mm two stages I knew it be super tight but at $99 what the heck.

I used the long MLK holiday weekend to build. Here are my modification notes to my build so far.

View attachment 336313

Using the build instruction as a key:

View attachment 336314

B – replace short nose cone coupler with 5 inch one to allow for Missile Works T3 or Eggfinder mini. Only ~8 inches so small antenna needed. Plan to use Missile Works or Eggfinder sleds.
E – Using Missile Works RRC3 for staging ignition. The RRC3 is ~4 inches long. So replaced the coupler with 8 inch one to allow room. Plan to use Missile Works 29 mm sled for the RRC3 mounting.
H – notched fin roots to allow for deeper recess need for retainer. Test with your motor since clearance vary with motor.
J – cut slot centering rings to allow 3/16” break line to pass, used epoxy to seal. Shaved center rings carefully to allow clearance for break-line making sure still lined up.

photo of retainer notched

View attachment 336317

I – added slight groove to make some room for 3/16” ridge break line. Used 29mm Giant Leap slim line retainer notched for access. Used 1 ½ bar of aluminum to tighten/loosen. Added a bulk head plate to seal top of coupler. Drilled hole in center of coupler, added T-Nut and ¼” threaded rod for altimeter bay. Added 1/8” inch kelvar to harness anchor.

photo of shooter wire fished into 3/16" break line

View attachment 336318

photo of retainer seated with no motor

View attachment 336319

photo of motor in tube without retainer

View attachment 336320

photo of motor with retainer installed

View attachment 336321

K – Added vent switch band. Allow inter-coupler length to allow motor and retainer
N – Plan to use Garmin DC40 for tracking and Stratogger for parachute deployment so I needed more room coupler provided. Used 6 inch one for the extra room. Added threaded rod and 4 inch bulk and air frame couplers to seal coupler. Added U ring to attached harness to booster.
O – Added rail buttons to booster section only.
Q – Added Aerotech 54mm retainer. Added 1 inch Kevlar to harness anchor.
How far in is that motor?

Sent from my Pixel XL using Rocketry Forum mobile app
 
I'll have the apache portion from mine at the SARG launch for a shakedown flight.
 
It's the Krushnic effect that kills the performance from a recessed motor. The aft end will be fried if that is the butt end of the recessed motor on the sustainer. Secondly, If running a Garmin dog tracker, always, always, always do a dry run meaning
load empty motor cases with contained ematches all around and turn everything on and let sit for 30 minutes to an hour. If nothing pops or the altimeters don't shut down and recycle you stand a chance of some success.
Some altimeters cannot tolerate the 2 watt Rf signal of a Garmin Dog tracker on the MURS frequency. Unless one knows for sure, I sure as heck wouldn't be trying it blindly on a two stage rocket unless perhaps the system was turned on remotely.

David, I say fly that sustainer as a single stage and see what happens unless you just mocked it up. If the epoxy has set, you might have to start over. Anyone else have other thoughts?

Kurt
 
It's the Krushnic effect that kills the performance from a recessed motor. The aft end will be fried if that is the butt end of the recessed motor on the sustainer. Secondly, If running a Garmin dog tracker, always, always, always do a dry run meaning
load empty motor cases with contained ematches all around and turn everything on and let sit for 30 minutes to an hour. If nothing pops or the altimeters don't shut down and recycle you stand a chance of some success.
Some altimeters cannot tolerate the 2 watt Rf signal of a Garmin Dog tracker on the MURS frequency. Unless one knows for sure, I sure as heck wouldn't be trying it blindly on a two stage rocket unless perhaps the system was turned on remotely.

David, I say fly that sustainer as a single stage and see what happens unless you just mocked it up. If the epoxy has set, you might have to start over. Anyone else have other thoughts?

Kurt

Kurt I think after at least 19 hours, the epoxy has set, no?
 
It's the Krushnic effect that kills the performance from a recessed motor. The aft end will be fried if that is the butt end of the recessed motor on the sustainer. Secondly, If running a Garmin dog tracker, always, always, always do a dry run meaning
load empty motor cases with contained ematches all around and turn everything on and let sit for 30 minutes to an hour. If nothing pops or the altimeters don't shut down and recycle you stand a chance of some success.
Some altimeters cannot tolerate the 2 watt Rf signal of a Garmin Dog tracker on the MURS frequency. Unless one knows for sure, I sure as heck wouldn't be trying it blindly on a two stage rocket unless perhaps the system was turned on remotely.

David, I say fly that sustainer as a single stage and see what happens unless you just mocked it up. If the epoxy has set, you might have to start over. Anyone else have other thoughts?

Kurt

Thanks for your comment, Garmin DC40 works fine with Stratologger. No issued with the same setup in my Double Shot.
 
Looks like fun, David. What two motors are you planning on, and what is the expected altitude?

Sustainer will be a G138T or H238T, Booster J460T.

The J460T should take it around 800 ft and the G138 or H238 will take to ~4,500 ft.

I've used the J460T in the Double Shot with very reproducible resutls.
 
Thanks for your comment, Garmin DC40 works fine with Stratologger. No issued with the same setup in my Double Shot.

Then you would be good to go. I'd still be worried about the recessed motor toasting the aft end.
I'd still mock up and test the setup because with wires everywhere, if Rf gets into your altimeters it could be a less than happy day.

OMG5.jpgOMG.jpgOMG1.jpg

Garmin DC 40, two deployment altimeters, O motor. Must've come in from pretty high
and fast. Took a backhoe to get out and 5 feet of rocket was left in ground because
landowner graciously said it was deep enough for him.

Kurt
 
Kurt I think after at least 19 hours, the epoxy has set, no?

Yes with the fins. But perhaps......

If going with MD in the sustainer. I'd do whatever to avoid a recessed motor. One might have to get creative. I'd be looking at HE ignition in that case with a good tape job.

Me, I'm looking at stock as I would bust every nearby (that is <400 miles) waiver to me if doing something
extravagant.

Anywho, I'll be watching and very impressed if this works and hats off then. Kurt
 
Sustainer will be a G138T or H238T, Booster J460T.

The J460T should take it around 800 ft and the G138 or H238 will take to ~4,500 ft.

I've used the J460T in the Double shoot with very reproducible resutls.

Sounds good. Will you be flying it at Snow Ranch?
 
Just took little off one side of centering ring to allow clearance of brake line. This provided clearance for wires without pointing exhaust at tube.


Sent from my iPhone using Rocketry Forum
 
How did you get the retainer/mm offset to one side for the wire to pass freely?
Optical illusion or am I seeing correct..looks snug to one wall and roomy on wire side.

Boy after blowing the picture up I see what you mean CJ. That's one heck of an optical "delusion" with that wire at the top giving the appearance of the motor being
canted downward. If you are certain it's straight David, ok. If it's not, you'll see a corkscrew flight. You going to try and do a test flight with the
sustainer alone? Might be prudent to put us naysayers to rest and tuck our tails between our legs between corkscrewing and butt end burning of the sustainer. Kurt
 
Please check my website for launches .

I normally create personal launch report and post too.

This is just my build and not advocating as the only way to accomplish. Please post your builds.

I did consider engine hooks for retention too but I wanted to be able to use Aerotech 29/40-120 and other aerotech 29 mm cases.
 
Just took little off one side of centering ring to allow clearance of brake line. This provided clearance for wires without pointing exhaust at tube.


That's a novel approach & looks like it may work well.
That small bit off vertical angle may not be noticeable at all, if the booster thrust is substantial enough to keep sustainer up to a higher speed.

You'll find out soon enough, best of luck with your flights.
There are usually several means to an end. With over 300 of these kits being built, I'm sure we'll see some varied & novel approaches. :dark:
 
Successful flight at TCC Feb club launch this weekend - TCC is host of LDRS this year. No issues, no damage. Ready to fly again...maybe at Holtville Havoc or at LDRS.

Nike Apache Two Stage small.jpg

Some posted concerns about tube damage from the design... none so far.

Here a photo immediately at recovery.. with carbon on the tube.

2nd stage after flight.jpg

After one wipe with baby wipe almost back to clean original tube.

2nd stage after flight after baby wipe carbon off small.jpg

Also for the folks who always comment about Garmin Astro (DC-40) dog trackers and electronic (Stratologger SL100). Here is a photo of configuration used in this weekend's successful launch. You'll see that they are next to each other and not an issue.

Nike Apache 1st stage ebay SL100 and DC-40 small.jpg

See personal launch report under local launches or youtube video below.

[YOUTUBE]1njSnBgbk-w[/YOUTUBE]
 
I'm glad it all worked out just fine. Great choice of motors..J-460-T staging to a H-238-T [last one correct?]

Was there separation charge or just drag?
Sustainer ignition delay setting? Seemed to be a 2.5-3 second by video, but there is always time for coming up to pressure.

All in all it was an outstanding first flight...congratulations!
You had a bit of spin, does not look like that was due to offset motor, as it continued after burnout. [before anyone makes comments about that...lol]
 
I'm glad it all worked out just fine. Great choice of motors..J-460-T staging to a H-238-T [last one correct?]

Correct Aerotech H238T... considered G138T but want more push.

Was there separation charge or just drag?

Drag... need to fine tune and put some tape on coupler.. too loose and released a little early.


Sustainer ignition delay setting? Seemed to be a 2.5-3 second by video, but there is always time for coming up to pressure.

Ignition was set on the AUX of RCC3+ for 1.8 sec... the published burn out time of the J460T.

All in all it was an outstanding first flight...congratulations!
You had a bit of spin, does not look like that was due to offset motor, as it continued after burnout. [before anyone makes comments about that...lol]

Spin was normal for my rockets... check out my other videos... I eyeball my fins or weight inbalance from taping a camera to side of the rocket, etc.... probably more to do with that than offsets of motor or phase of moon or what crop was in the field.

Thanks, many way to build and fly, none wrong if you can recover and fly again.
 
Correct Aerotech H238T... considered G138T but want more push.



Drag... need to fine tune and put some tape on coupler.. too loose and released a little early.




Ignition was set on the AUX of RCC3+ for 1.8 sec... the published burn out time of the J460T.



Spin was normal for my rockets... check out my other videos... I eyeball my fins or weight inbalance from taping a camera to side of the rocket, etc.... probably more to with that than offsets of motor or phase of moon or what crop was in the field.

Thanks, many way to build and fly, none wrong if you can recover and fly again.


Absolutely awesome launch! I need to get mine going here as well. Not going to quite be ready for LUNAR's March launch. April maybe.
 
Update:

Flew my Nike Apache at Holtville Havoc 2 this past weekend.... great 2nd flight.. tried 18 inch thin mil chute ok but still a little to fast a decent... will try 25 inch next.

na1.jpg na2.jpg na3.jpg

See personal launch report in regional launch section.
 
Does anyone have a Rocksim file for this kit? I have had this kit since 2017 and haven't built it yet. I do not have the computer skills to impute all the data into Rocksim and cant seem to figure it out. I would highly appreciate it if anyone has a rock sim file for the Madcow 4" Nike-Apache that they could send me.
 
I don't recall where I got the Rocksim file. I have a verified OpenRocket that I made from this one.
 

Attachments

  • nike-apache.rkt
    50.6 KB · Views: 13
Back
Top