Fiberglass 4" Honest John long build

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Rethought my AvBay, 3d printed some rail button standoffs, and decided to 3d print the jet nozzles for effect.

All that's left is add a switch band, vent holes, ground test, and paint.

Last step will be an AeroTech K550W up, up, and away.
 

Attachments

  • IMG_3312.jpg
    IMG_3312.jpg
    1.4 MB · Views: 0
  • IMG_3309.jpg
    IMG_3309.jpg
    1.2 MB · Views: 0
  • IMG_3310.jpg
    IMG_3310.jpg
    3.4 MB · Views: 0
  • IMG_3311.jpg
    IMG_3311.jpg
    2.1 MB · Views: 0
Received my Wildman 1"in. switch band tonight and installed it like a kid with a magic decoder ring. I hope to fly this rocket in either February or March.
 

Attachments

  • IMG_3334.jpg
    IMG_3334.jpg
    2.6 MB · Views: 0
  • IMG_3335.jpg
    IMG_3335.jpg
    2.7 MB · Views: 0
Rail button standoffs final version. I need longer screws and to epoxy the mounts down tomorrow. Then onto drill vent holes and sheer pin holes.
 

Attachments

  • image.jpg
    image.jpg
    3.9 MB · Views: 0
  • image.jpg
    image.jpg
    2.5 MB · Views: 0
Rail button standoffs final version. I need longer screws and to epoxy the mounts down tomorrow. Then onto drill vent holes and sheer pin holes.
Just a little insight here if you're at all interested in downsizing those standoffs:
For my 7.5" HoJo I used a nut tied on a bit of string as a pseudo plum bob and held it against the widest part of the nosecone, then measured from the string to the lower airframe. I only needed about an inch of standoff, and I did solid 100% infill PETG standoffs the same OD as the rail button. Bottom button into the rear ring an the upper button through the phenolic tube, backed with glass, and secured with a jam jut and a big washer.

Fully loaded with an M and four Js it was a little over 50 lbs and they worked great!
 
Just a little insight here if you're at all interested in downsizing those standoffs:
For my 7.5" HoJo I used a nut tied on a bit of string as a pseudo plum bob and held it against the widest part of the nosecone, then measured from the string to the lower airframe. I only needed about an inch of standoff, and I did solid 100% infill PETG standoffs the same OD as the rail button. Bottom button into the rear ring an the upper button through the phenolic tube, backed with glass, and secured with a jam jut and a big washer.

Fully loaded with an M and four Js it was a little over 50 lbs and they worked great!
Printing smaller aero standoffs, thank you for the idea. Keep making awesome videos, I’m subscribed on YouTube.
 

Attachments

  • IMG_3357.jpeg
    IMG_3357.jpeg
    1.6 MB · Views: 0
Epoxied the standoffs inplace tonight and hooked up the altimeters to the laptop to ensure the Primary was correct and the secondary was correct.
Settings are:

  • Primary Altimeter
    • Droge at Apogee
    • Main at 900 ft.​
  • Secondary Altimeter
    • Drouge at Apogee + 2sec.​
    • Main at 300 ft.​
Let me know if it is wiser for the Secondary Altimeter to be at Apogee + 1 sec. instead?

All that's left is to install charge wells, drill vent and shear pin holes, and test!

Almost forgot to epoxy the Honest John 3D print jets on.
 
You might want to set your secondary main at 500ft. I set my chute release at 300ft and it was very low when the chute opened up. I have it set at 500ft now. Even as a backup you still need more altitude than 300ft just my 2cents. Nice build.
 
Would set your main between 700 and 500 with your back up 200 feet after. FWIW, haven’t set a main to deploy above 700, and now all are at 500.

Apogee +2 is fine for the drogue back up.
 
Drilled all of the sear pin holes, vent holes, and mounted the charge wells. If I have time tomorrow it will be a ejection test time. 3 pins on top and 3 pins on bottom (2-56 pins)
 

Attachments

  • IMG_3369.jpg
    IMG_3369.jpg
    785.2 KB · Views: 0
  • IMG_3370.jpg
    IMG_3370.jpg
    801.2 KB · Views: 0
Back
Top