Formula 98

[viciouspeanut]

So I just pulled out my formula 98 from 2016 to get ready to build.

I guess I’m fiberglass rocket dumb but I have 2 av bay bulkheads which don’t have holes for all thread in them like I’m used to with LOC but I guess it’s so I can choose my own spacing?

Also I have 3 smaller bulkheads and I figure 2 are for a second av bay in the nose cone coupler?

The third small one is for? Installing higher up in the hose done for what purpose? Somewhere else to put avionics if you want? If so that’s like 3 av bays type areas. Interesting.

 

[sharkbait]

So I just pulled out my formula 98 from 2016 to get ready to build.

I guess I’m fiberglass rocket dumb but I have 2 av bay bulkheads which don’t have holes for all thread in them like I’m used to with LOC but I guess it’s so I can choose my own spacing?

Also I have 3 smaller bulkheads and I figure 2 are for a second av bay in the nose cone coupler?

The third small one is for? Installing higher up in the hose done for what purpose? Somewhere else to put avionics if you want? If so that’s like 3 av bays type areas. Interesting.

Most of the older kits didn’t have 1 piece AV bulkheads. You glued the two smaller bulkheads (coupler bulkplates) to the two larger bulkheads (airframe bulkplates) to create two E-bay lids, the third bulkplate was glued to the nose cone coupler

 

[Hobie1dog]

post pictures of your build for us.

 

[viciouspeanut]

Most of the older kits didn’t have 1 piece AV bulkheads. You glued the two smaller bulkheads (coupler bulkplates) to the two larger bulkheads (airframe bulkplates) to create two E-bay lids, the third bulkplate was glued to the nose cone coupler

Ah this makes completely sense. I was thinking that it didn’t have a “stuffy coupler” inside so it didn’t have the ledge but it’s actually the stepped bulkhead I was missing. Makes much more sense!

Related note - what’s the best way to ensure you drill evenly for allthread hole spacing? Or do you only use one center rod on this? That would seem odd on a 10lb rocket though

 

[bmonagle]

What I did was to bolt the 4 pieces together through the center hole, then drill the allthread holes on a drill press.

One thing you need to be careful of, the nose cone is VERY heavy. With a 15 foot shock cord on the drogue, my main chute deployed at apogee several times. I finally figured that it was from the drogue deployment being too severe and breaking my 2-56 shear bolts. I upsized to 4-40 and the same thing happened. Make sure that you use a longer shock cord and/or use several taped Z-folds on your drogue shock cord to reduce the stress on the shear pins.

 

[cls]

what’s the best way to ensure you drill evenly for allthread hole spacing?

Clamp the stack together, all 4 plates, double check everything is centered... Drill through at the 2 places you want. Measure twice, cut once.

Go slow. Use a drill press. Start with pilot holes, drill successively larger holes to 3/16" or 1/4" for the threaded rod you're using.

 

[viciouspeanut]

What I did was to bolt the 4 pieces together through the center hole, then drill the allthread holes on a drill press.

One thing you need to be careful of, the nose cone is VERY heavy. With a 15 foot shock cord on the drogue, my main chute deployed at apogee several times. I finally figured that it was from the drogue deployment being too severe and breaking my 2-56 shear bolts. I upsized to 4-40 and the same thing happened. Make sure that you use a longer shock cord and/or use several taped Z-folds on your drogue shock cord to reduce the stress on the shear pins.

Sounds good, I suppose my question was more about how to ensure I get the spacing perfect for the sled I’m using. I need to find my calipers and measure center to center lol

Noted on the nose cone. I have 25’ harnesses and often do the z fold. How many 2-56 shear pins were you using? I can certainly get some 4-40, just haven’t had a need this far.

 

[viciouspeanut]

Clamp the stack together, all 4 plates, double check everything is centered... Drill through at the 2 places you want. Measure twice, cut once.

Go slow. Use a drill press. Start with pilot holes, drill successively larger holes to 3/16" or 1/4" for the threaded rod you're using.

Great, will do!

Also I’ll try and remember to take some pics to post. I’ll need to clear the wasps that made a home in my drill press haha. Should be super fun!

 

[tim cubbedge]

How many 2-56 shear pins were you using?

I use 3 on the NC and 2 on the booster, all are 2-56 pins.

 

[Titan II]

Or do you only use one center rod on this? That would seem odd on a 10lb rocket though

One is common for a rocket that weight.

 

[gdjsky01]

I did a build thread years ago. But I put the electronics in the nose.