sono tube

[terry30]

when using sono tube how important is it to glass the inside of the tube? Being that the outside is already glassed. I have heard mixed reviews. Any ideas would be a big help.

 

[narmember]

when using sono tube how important is it to glass the inside of the tube? Being that the outside is already glassed. I have heard mixed reviews. Any ideas would be a big help.

Are you flying an O or a P?

 

[terry30]

most likely an O

 

[Mark Clark]

For an O motor I would only glass the inside at high stress areas such as the areas between the fins, the forward centering ring if it is being used as a thrust plate and where the launch lugs attach. I would also foam the fin area.
I have done some and seen many sonotube projects with no glass on the tube that worked, the best reason to glass the outside is to make finishing easier and improve the toughness of the surface for handling. The tube is quite strong.

Mark

 

[narmember]

Glassing the inside, while building a better composite structure, makes assembling components more difficult (due to unevenness, overlapping of fabric). Something to be concerned about when the coupler section needs to slide out. If you watch enough videos, many of the projects fail at the coupler or fincan transitions, and as Mark suggests, beef those up (X inside the coupler). Research 'concrete - forms' in your area to eliminate couplers (diameters 6"-5' up to 20' in length). But you are so far outside the "expertise" of this forum (including mine) I'd suggest other resources:
Nike Project Contact Wedge
TQC Message Board
BORG Email list
Both have had large projects discussions in the past.

 

[Mark Clark]

snip Research 'concrete - forms' in your area to eliminate couplers (diameters 6"-5' up to 20' in length). QUOTE]

He is right on here. Do NOT go to Home Depot to get the tubes unless it is really short. By going to a real contractor supply house you can get a tube that will be one piece for the airframe. For strength and weight it will be better, you have to borrow a trailer to move it though. Some of the tubes have a release layer in them but it will peel right out, children are good for this job.

Mark

 

[narmember]

Some of the tubes have a release layer in them but it will peel right out, children are good for this job.

Mark

Paul had suggested we leave the release in the area where the coupler would slide. Alas, that was right after we removed it. This is one step where a 10' pole comes in handy as it gives you something to wind the layer onto.

 

[Mark Clark]

I remove it because the stuff we get here is a wax and when it is very hot it gets sticky. So it is peeled, I soak the area the coupler will be in CyA glue and sand it smooth.
I use Robin's Daughter to get the liner out, she did not like it when I rolled the tube across the room.

Mark

 

[terry30]

good stuff. thanks guys!!!!!

 

[narmember]

I remove it because the stuff we get here is a wax and when it is very hot it gets sticky. So it is peeled, I soak the area the coupler will be in CyA glue and sand it smooth.
I use Robin's Daughter to get the liner out, she did not like it when I rolled the tube across the room.

Mark

I think you oweeee meeee a neeeew keeeeyboard.

If I recall, we used epoxy in a similar way. Speaking of getting stuck, the tomahawk nose (fiberglass) wouldn't go into the payload bay after the parts spent the morning in the hot sun. Had to toss it into the truck with the AC blasting till it could be slid in. The design had it fixed so that wasn't a flight issue, but something to watch out for if you expect it to come off for a chute to come out and the rocket has been at the pad a while.

 

[AZ_Ron]

I used 16" Sonotube to build the Diablo in the HPR section of the forums. Mark Clark signed off on my L3 cert after the flight. There was NO fiberglass and no Epoxy in this rocket.
I had my 9 year old daughter peel the wax lining out.
The flight was on an AMW N2800WW, and is now loaded with an O-4000 made by Conway Stevens and James Russell.
I think the reason I can get away with this not being 'glassed is that it's very short. There is about 24" of airframe that is not in someway supported... part of it by the coupler in the booster, and part by the shoulder of the NC.
The HillBillies have flown the Gila Monster on clusters of 'M's with up to 'P' total impulse... it was not 'glassed, but they did 'paint' the tubes with West Systems Epoxy.

Ron