I am contemplating making an access panel on the side of the BT-101 airframe tube adjacent to the shock leader line hook (i.e. near the base). Taking care, I could cut out the area, insert and CA a partial BT-101 coupler to support the panel once buttoned back up up and secure the panel with near flush headed screws secured on the other side with T-nuts. I am confident that using CA to reinforce the removable panel would retain its integrity longer term and once secured, the structural integrity of the BT-101 would be pretty much intact.

I recently was made aware that the Eagle Claw double latch hooks(uncertain of which size) have been found inadequate on some mid-power rockets, so this does concern me as I used the larger version of those hooks rather than the "safety pin" type of hook.

As about the largest engine this bird will likely fly is in the G50 class +/- this concern may be unwarranted.

At the moment, I have no access to the area as I have already moved past that point in the construction, but the proposed access panel would give me that access and also allow me to swap out the leader line if necessary (i.e. the leader lines are NOT secured at any further point beyond)

Thoughts?

David

I will throw my two cents in here.
You are doing a very nice build but I think adding an 'access door' onto an already complicated structure for a NON-HPR rocket is adding complexity you don't need.
You may find yourself flying it on the higher thrust G's I suggested, and with all this mass a HPR H128 would not be out of reality either.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, AGITATION, CHAOS, TURMOIL, FIASCOS, AGGRAVATION, INSTIGATION, NUISANCE-ACTION, and HAVOC !

My suggestion is to make the internal portion of your recovery system permanent, eliminating the hook. You can make a permanent loop at the other end that can receive a quick link or other positive retention method that will not fail.

Motor size isn't that important. The total weight of the rocket and velocity at deployment are. An off-vertical flight and/or a longer than normal delay can result in some pretty high ejection velocities that can yank a wire hook apart.

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I love sanding.

Don't forget to stop your leader short of the end of the BT. Wide shock cord material will spread the load and prevent zippers on normal ejections. The corrugated wraps will help strengthen the end of the BT, but won't handle that leader wire on faster ejection velocities that sometimes occur.

__________________
I love sanding.

As the hook is no longer non-invasively accessible, the access door was a thought as to how to either swap out the suspect hook or eliminate it. Yes, I did think about directly hooking the leader lines onto the eyebolt, but I would have had to pry the eyebolt open slightly and I really did not contemplate the hook failure as a factor (my mistake).

As I have 3 leader lines installed, a non invasive mod would involve me securing the leader lines as they pass thru the top two CRs (I still have access to those areas) using JB Weld. That would spread the load to 3 of the 4 CRs. I really don't want to just go on the hope that the hook holds. assuming that the hook failed, it would likely remain attached to the leader lines and snag on the next CR up as the hole thru which the leader lines pass in each CR is small. Whether the .125 thin ply would snap is another question.

David

Well, my confidence in the hook shattered, there really was no alternative but to cut a strategic, small access hole adjacent to the hook being SUPER careful, removing the offending hook and attaching the leader lines directly to the eyebolt.

I will back support the opening wth a couple of strips of BTR-101 coupler.

The repair was pretty straight forward and I don't think it damaged the integrity of the BT-101 in the least. With the 3 leaders all hooked directly to the eyebolt, I see no need for further access, so I am closing up the access area permanently.

While the last pic does not really show it well, the patch is glassy smooth with no ridges or edges. I will put on a couple more layers of CA followed by sanding and call this a lesson learned.

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