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View Full Version : But is it the ULTIMATE Pop Lug


jharding58
11-02-2010, 02:06 PM
Just finished up a Gemini and the customer wanted (well, I offered) a pop lug for the model. I built up this one and took the advice from some other posts with regard to adding the rib along the strip to increase rigidity. Then I saw a piece of loop sided velcro and determined that the contact point could use a little padding.

So; do I need to add something more than fillets at the LL attachment?

Jerry Irvine
11-02-2010, 03:41 PM
Just finished up a Gemini and the customer wanted (well, I offered) a pop lug for the model. I built up this one and took the advice from some other posts with regard to adding the rib along the strip to increase rigidity. The I saw a piece of loop sided velcro and determined that the contact point could use a little padding.

So; do I need to add something more than fillets at the LL attachment?
I have on occasion had top lugs pop off when it hits the rod stop. I started using masking tape there to make the impact softer.

If you reinforce the lugs, give extra care to the top one. I see you have a narrow bond space since the lug is on the edge of the reinforcing strip. Maybe put two short pieces of strip on the sides of both lugs to improve bond area? That wouldn't weigh much or change the appearance appreciably.

Are you going to piston launch it too? :D

Jerry

jharding58
11-02-2010, 05:17 PM
I had read that a three inch piece of tape wrapped around the top serves as a buffer, even using a section of tubing - probably softer fuel tubing on the top, to keep the bounce. I suppose it needs to go on and off pretty easily since you have to replace it for each launch. Thanks for the observations on the lug attachment - they are epoxy but I did not feel that they had enough meat on the joint.

Not for me to launch, but I included standard lugs also.

Jerry Irvine
11-03-2010, 09:38 AM
I had read that a three inch piece of tape wrapped around the top serves as a buffer, even using a section of tubing - probably softer fuel tubing on the top, to keep the bounce. I suppose it needs to go on and off pretty easily since you have to replace it for each launch. Thanks for the observations on the lug attachment - they are epoxy but I did not feel that they had enough meat on the joint.

Not for me to launch, but I included standard lugs also.
I like the idea of a pop lug for a scale rocket. It does require a hole in the rocket. That begs the question, why not set it up for removable rail guides?

Jerry

jharding58
11-03-2010, 07:35 PM
I like the idea of a pop lug for a scale rocket. It does require a hole in the rocket. That begs the question, why not set it up for removable rail guides?

Jerry

I suppose so. Which further goes to could you use rare earth magnets inside the tube to attach the guides to the model from the exterior? But then this thing is only 24" long.

Brain
11-04-2010, 03:46 PM
I suppose so. Which further goes to could you use rare earth magnets inside the tube to attach the guides to the model from the exterior? But then this thing is only 24" long.
Has anyone ever considered - or even experimented with - a launch rail system for LPRs? I can't imagine why LPRs couldn't use a scaled-down version of what the big boys use...

Chas Russell
11-04-2010, 04:24 PM
Estes offered a simple "C" rail made of aluminum. I had a couple of sections way back when, but the box was stolen out of a storage unit along with a lot of items I really would like to have now.

Go to www.ninfinger.org and go to Sven's model rocket page. Find the 1969 Estes catalog. The "C" rail is on page 88. It is easier to start with the back page and work towards the front. Sorry, but I was not able to get the link to copy.

Chas

P.S. I think it was simply an aluminum flange for holding sliding curtains. One of the big box stores may sell long sections of them. Estes suggested nylon screws, elevated launch lugs, or a "T" made out of wood to launch a model from the "C" rails.

tbzep
11-04-2010, 04:36 PM
I like the idea of a pop lug for a scale rocket. It does require a hole in the rocket.
Jerry

It's sometimes possible to put the hole where there is a vent or a some other structure on the real rocket that will help hide the hole. The pop lug can be varied in length to match the hole's location.

I don't know how they judge scale, but it seems to me if they take away points for lugs, buttons, pop pod holes,etc., they should take off more for one or two big launch lugs than for one tiny hole. :confused:

jharding58
11-04-2010, 04:53 PM
I thought of putting the upper hole into the decal representing the interstage.

I also came up with the notion of gluing the lower lug to the removable clear fin can and then using a strip of cardstock or heavy bond paper for the upper lug. Glue the lug to the bottom of a 3" strip of paper, fold the top 1/2" over and trap it between the capsule and the inner BT, then crease the strip at the junction of the capsule adapter and the main BT. Launch should put the paper into tension and the drag of the lug should hold it against the tube, doubt that NAR would go for it but it would render no lugs on the model.

But would I need a streamer for the upper lug since it detaches from the model... hmmm.

jharding58
11-04-2010, 04:55 PM
Estes offered a simple "C" rail made of aluminum. I had a couple of sections way back when, but the box was stolen out of a storage unit along with a lot of items I really would like to have now.

Go to www.ninfinger.org and go to Sven's model rocket page. Find the 1969 Estes catalog. The "C" rail is on page 88. It is easier to start with the back page and work towards the front. Sorry, but I was not able to get the link to copy.

Chas

P.S. I think it was simply an aluminum flange for holding sliding curtains. One of the big box stores may sell long sections of them. Estes suggested nylon screws, elevated launch lugs, or a "T" made out of wood to launch a model from the "C" rails.

Some of the earliest launches I recal reading about happened within a tower - seems the impact of the early sounding rockets took hold quick.

jharding58
11-04-2010, 04:56 PM
Has anyone ever considered - or even experimented with - a launch rail system for LPRs? I can't imagine why LPRs couldn't use a scaled-down version of what the big boys use...

Is it just me being sensitive or does LPR's sound a little too close to Lepers? ;)

GD&R

Bill
11-04-2010, 07:46 PM
I finally put in the effort to find where I had posted about this: http://www.rocketryforumarchive.com/showpost.php?p=217873&postcount=435

Attach the launch lugs onto a strap which wraps around the rocket and falls off after it leaves the rod.


Bill

Ltvscout
11-04-2010, 07:59 PM
Estes offered a simple "C" rail made of aluminum. I had a couple of sections way back when, but the box was stolen out of a storage unit along with a lot of items I really would like to have now.

Go to www.ninfinger.org and go to Sven's model rocket page. Find the 1969 Estes catalog. The "C" rail is on page 88. It is easier to start with the back page and work towards the front. Sorry, but I was not able to get the link to copy.

Chas

P.S. I think it was simply an aluminum flange for holding sliding curtains. One of the big box stores may sell long sections of them. Estes suggested nylon screws, elevated launch lugs, or a "T" made out of wood to launch a model from the "C" rails.
Back when I got back into rocketry in '98 I had a real hardon for getting the original c-rail. Kurt Schachner and I looked high and low. We ended up getting a number of sections along with the joiners (which was REALLY hard to find) from a hobby shop in a suburb in LA. I'm trying to recall the name, I think it was something like Bellflower Hobbies. From what I recall they ended up going out of business in the early 2000's due to damage from an earthquake (plus they were in a really BAD area of town).

Moral of the story is that I have a number of sections of Estes C-rail with the joiners that I'll be selling sooner rather than later. ;)

tbzep
11-04-2010, 08:58 PM
Moral of the story is that I have a number of sections of Estes C-rail with the joiners that I'll be selling sooner rather than later. ;)

Got any photos of them? Was there any way to use them on Port-a-Pads or Tilt-a-Pads? I've always been curious about them.

Ltvscout
11-05-2010, 08:33 AM
Got any photos of them? Was there any way to use them on Port-a-Pads or Tilt-a-Pads? I've always been curious about them.
Not at this time since they're buried.

They did/do fit into the old style pads.

Shreadvector
11-05-2010, 08:56 AM
Back when I got back into rocketry in '98 I had a real hardon for getting the original c-rail. Kurt Schachner and I looked high and low. We ended up getting a number of sections along with the joiners (which was REALLY hard to find) from a hobby shop in a suburb in LA. I'm trying to recall the name, I think it was something like Bellflower Hobbies. From what I recall they ended up going out of business in the early 2000's due to damage from an earthquake (plus they were in a really BAD area of town).

Moral of the story is that I have a number of sections of Estes C-rail with the joiners that I'll be selling sooner rather than later. ;)

Earl's Bellflower hobbies.

Earthquake retrofit required owner (very old and not named Earle - I am pretty sure it was John/'Jack') to clear out the attic warehouse which was a nightmare. He decided to retire and he trucked whatever was not sold (big sale) away. later, he tried to sell some of it on eBay. After that, he donated the rest ot a church which held a parking lot sale. Pegasus Hobbies (Dianna) in Montclair got wind of the sale and bought the remaining truckload for their giant store.

They still have tons of old stock including B4-6 motors, The parts may still be hiding somewhere. Give them a call. 909-982-6507. They may also still have some North Coast by Estes launch pads or kits.

Brain
11-05-2010, 02:18 PM
Is it just me being sensitive or does LPR's sound a little too close to Lepers? ;)

GD&R
That's as bad as walking through a leper colony asking, "What's eatin' you?!?" :p