Do any of you have any advice for securing pods to the tips of fins (for example the older Estes Interceptor)? Have any of you tried TTW techniques with pods? Some other technique?
Thanks.
Thanks.
Technique for securely mounting outboard pods?
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hornet driver
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Yea, ttw is about the only way to go and stand a chance of them not being knocked off.
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Certainly not as good as TTW technique, but more secure than simple attachment.
I use what I call "balsa fillets."
Cut a thin strip of balsa (if you use 1/16", cut it 1/16" wide and the length of your fin attachment). Draw your position line down the length of the pod where you want the fin to go. Glue this in place and allow to dry.
Use the double glue joint technique, use this as a base/guide to glue the pod to the fin. If desired for extra strength and symmetry, you can add a second strip of equal length on the opposite side once the pod/fin joint is dry.
Advantages:
Provides a stronger joint (basically more surface area of adhesion) than simple attachment (doesn't beat TTW)
Assuming you draw your line straight and put the first strip on aligned to your line, just about guarantees perfect alignment. This can be tough when you "free hand it." Does not beat TTW (assuming in THAT case your CUTS are straight!)
Disadvantage:
Some may not like the aesthetics, although with a 1/16" fillet you can barely see it, and you can probably cover it with Titebond Trim and Molding glue fillet when done.
This technique also works well with attaching fins to the body tube, and might be one to consider when working with kids to get perfectly aligned fins. Although it takes more time (it adds a step, you have to attach and allow to dry, so doesn't work well with a rapid build rocket party), in comibination with double glue joint technique the fin attachment is faster and the longitudinal alignment (with the rocket axis) should be perfect.
I use what I call "balsa fillets."
Cut a thin strip of balsa (if you use 1/16", cut it 1/16" wide and the length of your fin attachment). Draw your position line down the length of the pod where you want the fin to go. Glue this in place and allow to dry.
Use the double glue joint technique, use this as a base/guide to glue the pod to the fin. If desired for extra strength and symmetry, you can add a second strip of equal length on the opposite side once the pod/fin joint is dry.
Advantages:
Provides a stronger joint (basically more surface area of adhesion) than simple attachment (doesn't beat TTW)
Assuming you draw your line straight and put the first strip on aligned to your line, just about guarantees perfect alignment. This can be tough when you "free hand it." Does not beat TTW (assuming in THAT case your CUTS are straight!)
Disadvantage:
Some may not like the aesthetics, although with a 1/16" fillet you can barely see it, and you can probably cover it with Titebond Trim and Molding glue fillet when done.
This technique also works well with attaching fins to the body tube, and might be one to consider when working with kids to get perfectly aligned fins. Although it takes more time (it adds a step, you have to attach and allow to dry, so doesn't work well with a rapid build rocket party), in comibination with double glue joint technique the fin attachment is faster and the longitudinal alignment (with the rocket axis) should be perfect.
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powderburner
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If it's a "big" pod, I use fiberglass. Cover the fin up to the tip, around the pod, back down onto the opposite side of the fin.
hornet driver
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I gotta tell ya, that's not a bad idea ! I'd forgotten about that technique. In some cases you can sand the balsa strip down to make a fillet. It is a good option !!
ThirstyBarbarian
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I used a TTW technique when I added pods to my Mega Der Red Max. I cut a slot in one side of the tube to be used for the pod. The tab on the outside edge of the fin was sized to reach all the way through the tube and glue to the other side of the pod tube. That way I could fillet externally and also internally at the slot and internally where the tab contact the other side of the pod tube. Then I filled the pod with foam. This has been a pretty solid setup. I fly the rocket on HPR motors, and it lands on the pods, so they have been pretty tough so far.
These are non-functional pods, just for looks. If I had put motor mounts in the pods, I would have done them just like TTW fins, with the tab contacting the MMT in the pod.
These are non-functional pods, just for looks. If I had put motor mounts in the pods, I would have done them just like TTW fins, with the tab contacting the MMT in the pod.
If the pods aren't too big, you can glue, fillet, then use a strip of self-adhesive address label paper on each side of each pod...part on the wing and other part on half of the pod, then sand smooth. Should provide more strength.
Incidentally I'm working on a Madcow Bomarc and that has massive pods. The pods have slots in them and the pod pylons have very shallow tabs which are basically the thickness of the pod tubes. You build up the sides of the pylons (which are plywood) with balsa sheeting and apply epoxy fillets. Came out very strong. I wouldn't suggest this for the Interceptor, but good to know how it's done on a larger scale where it's designed to be strong.
Incidentally I'm working on a Madcow Bomarc and that has massive pods. The pods have slots in them and the pod pylons have very shallow tabs which are basically the thickness of the pod tubes. You build up the sides of the pylons (which are plywood) with balsa sheeting and apply epoxy fillets. Came out very strong. I wouldn't suggest this for the Interceptor, but good to know how it's done on a larger scale where it's designed to be strong.
I have the big Interceptor E. I was worried about the pods and the fin tips breaking off on impact.
My solution was to make them a tight press fit, no glue.
They do stay on during flight.
If it comes down in a squirrelly position, they come off with no breakage.
My 2 cents.
Mark
My solution was to make them a tight press fit, no glue.
They do stay on during flight.
If it comes down in a squirrelly position, they come off with no breakage.
My 2 cents.
Mark
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In conjunction with the TTW, you can then also foam the inside of the pod for more strength
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