Build thread for the Hail Mary.

[NTP2]

If you want to see the thread where I designed the thing go see https://www.rocketryforum.com/threads/scale-model-of-the-hail-mary.182128/
So now on to the first update…

 

[NTP2]

So the tubes are cut and motor mounts epoxied. But the 3d printed transition doesn’t fit, ideas?

 

[lakeroadster]

So the tubes are cut and motor mounts epoxied. But the 3d printed transition doesn’t fit, ideas?

Cut a (3/8") gap out of the outer tubes so that they overlap the center tube. Then glue them to the center tube.

​

 

[NTP2]

Cut a (3/8") gap out of the outer tubes so that they overlap the center tube. Then glue them to the center tube.

View attachment 609771

Ok, good idea.

Like this?

 

[lakeroadster]

Ok, good idea.

Like this?
View attachment 609790

You would cut a slot the full length of the two outer tubes.... then glue them to the center tube.

​

 

[NTP2]

You would cut a slot the full length of the two outer tubes.... then glue them to the center tube.

View attachment 609799​

Ok full length got it, thanks

 

[lakeroadster]

Use a small piece of aluminum angle and a hobby knife to cut the tubes... or maybe just scissors?

​

 

[NTP2]

or maybe just scissors?

With thick wall tubes I probably would just end up bending the scissors.

 

[NTP2]

Ok I followed @lakeroadster idea I messed up 2 times but I got 2 right and past me for once made my life easier by getting 2 tubes.
So I can make 2 to replace them.

 

[lakeroadster]

Ok I followed @lakeroadster idea I messed up 2 times but I got 2 right and past me for once made my life easier by getting 2 tubes.View attachment 609949
So I can make 2 to replace them.

Progress... is good!

Not sure what kind of tools you have access to... but a pair of sheet metal shears will work.

Or you can also use a mandrel clamped in a vice, such as a broom stick, and then use a hobby knife to cut the tube as it rests on the broom stick. You might need to open the slot up some more.

 

[NTP2]

You might need to open the slot up some more.

I have access to a lot of tools but they are in a cold garage so I just used a knife and pen. I also tested the fit and it is good I will need to cut more tubes to replace the ones I messed up on though.

 

[neil_w]

I would definitely clean up those cuts so you'll get a better joint between the tubes.

 

[NTP2]

I would definitely clean up those cuts so you'll get a better joint between the tubes.

Will do thanks, if you haven’t noticed this is my first time scratch building.

 

[NTP2]

My plan for attaching the tanks to the transition is to epoxy the center one.
Then do the sides like this.
And epoxy filet the corners. Is there any problems with that?

 

[lakeroadster]

Hmm.. J-B Kwik Epoxy sets up in 6 minutes. Might want to use regular J-B Weld.

And for the Tube-to-Tube joints, use wood glue (Gorilla Wood Glue or Titebond).

​

 

[NTP2]

And for the Tube-to-Tube joints, use wood glue (Gorilla Wood Glue or Titebond).

Is there a reason for that? I would think that an epoxy would be better. But what do I know

 

[neil_w]

Is there a reason for that? I would think that an epoxy would be better. But what do I know

Wood glue is ideal for paper and wood joints. You can use epoxy, but it just adds weight and is harder to work with.

 

[NTP2]

Wood glue is ideal for paper and wood joints. You can use epoxy, but it just adds weight and is harder to work with.

But the glassy stuff on top of the paper is plastic right?

 

[techrat]

But the glassy stuff on top of the paper is plastic right?

https://en.wikipedia.org/wiki/Glassine

 

[neil_w]

But the glassy stuff on top of the paper is plastic right?

Nope (see above). Nonetheless it can be beneficial to remove the glassine from areas that will be receiving glue, regardless of what glue you’re using.

 

[NTP2]

https://en.wikipedia.org/wiki/Glassine

Nope (see above). Nonetheless it can be beneficial to remove the glassine from areas that will be receiving glue, regardless of what glue you’re using.

I thought I would never see the day when something was NOT made of plastic.

 

[NTP2]

I have started to get everything glued together I had to use 5 minute epoxy (the clear stuff) because I ran out of wood glue and had a bad case of go fever but I did ruff up the glassine.

 

[NTP2]

Top epoxied on.

It’s starting to look like a rocket

 

[NTP2]

I epoxied the bottom on. Next FINS!

 

[NTP2]

How would you attach the fins? my plan is, since the rocket won’t see high speeds it should be ok to not use TTW and epoxy them to the surface. Opinions?

 

[NTP2]

Almost done with the fins, here is a pic.
Next MMts!

 

[neil_w]

In the future you should consider painting before attaching clear fins.

 

[cwbullet]

In the future you should consider painting before attaching clear fins.

Good point or just not painting at all.

 

[NTP2]

In the future you should consider painting before attaching clear fins.

I thought of that, after I had 2 fins on.

 

[techrat]

I thought of that, after I had 2 fins on.

Somebody has launch fever..... When in you're in such a rush to get it done, painting is only an afterthought..... Although, I have built a few rockets where I go through the whole checklist, I've got the shock cord, it's painted, and everything seems good... wait a minute, I forgot to glue on a launch lug!! Dammit!