LOC DOORKNOB - DUAL DEPLOY

[neond7]

My LOC Doorknob has been a great flying rocket, arrow straight flights every time. As I got more into dual deploy and flying higher, my motor ejection rockets started spending more time in the garage than at the field.

In my original build thread for this rocket, located HERE, someone had mentioned converting it to dual deploy. That always stuck in the back of my mind - so I recently ordered a 30" payload section and av-bay from LOC Precision. Today I finally got a chance to start on it.

Of course I had to test fit the parts - she is going to be a tall bird!!! I might add an additional rail button to increase stability on the rail since wasn't originally set up to be this tall.

So far today I have used 16 grams of Aeropoxy 6209 to epoxy the stiffy tube in the av-bay. I then glassed the wood bulkheads with one layer 5.8oz s-glass, and one layer 1.5oz deck cloth. I do this for two reasons - first to add a bit of strength to withstand the ejection charges, and second to make cleanup easier. I'll shoot some high temp clear on the surface to make it smooth as glass and it wipes clean. After I wetted out the fiberglass I applied some peel ply and sandwiched it between tiles and added some 20lb kitty litter containers to compress it.

My goal is to launch it a few times on large "K" motors, and then put it up on a CTI 54mm 6XL "L" impulse motor. The body tubes are glassed, and the fins have tip to tip glass, so it's built like a tank.

I'll probably pick up a new nose cone, as the current nose had a lot of nose weight added. It definitely won't need it with the added length. While I"m at it, I'll also order more peel ply this week so I can glass the payload section to match the already built lower half of the rocket.

 

[AHansom]

Glad your having fun with it. Do you want the rocket to be tall? If not you only have to put enough payload bay on to hold the recovery system.

 

[bill2654]

I think if your going with a new nose cone just put the altimeter in the nose cone. Make it cable cutter deploy and add what ever weight you need and that way you keep the look of a regular Door Knob. Just my :2:

 

[neond7]

Glad your having fun with it. Do you want the rocket to be tall? If not you only have to put enough payload bay on to hold the recovery system.

Good idea.... I may end up cutting 10" from the tube to keep the height more reasonable, it was looking a tad too tall. Especially when you consider its a 7.5" airframe!

The bulkheads came out very nice, I trimmed the fiberglass overhang last night while the epoxy was still green. I'll sand the edges smooth tonight and get a good fit into the av-bay.

Ill glass the switch band when I glass the body tube, I ran out of peel ply or I would have glassed it this weekend.

 

[qquake2k]

You must have a lot of cats. :tongue:

 

[neond7]

Finally got some time to get some work done on the av-bay.

As always, I upgraded to stainless u-bolts. Drilled out the holes and attached the parts using loc-tite.

Once the parts were attached, I lined up the sled, marked the lines, and mixed up a batch of Aeropoxy 6209 epoxy. I applied a nice bead and smooshed the rail guides down into the epoxy and smoothed the sides with a Popsicle stick.

I applied some weight to keep things flush and it's curing. Once it's cured I will install the blast caps and terminal blocks.

 

[neond7]

While I was attaching the Blast Caps, I decided to go ahead and install them for all the av-bays I've got in various stages of completion for other projects.

Since I'm going to be using dual SL100 altimeters, I "requisitioned" the four medium blast caps I had bought earlier for my L3 project.

I set up my Magnum av-bay for dual SL100's as well. I'll only use a single SL100 in my Hyperloc, so I only needed a pair of Blast caps for that one. I'll need to buy one more set so I can set up dual altimeters in my L3 project as well.

With all the Blast caps I'm using, Gary should be driving a Lexus before too long! Great product, and they are reasonably priced.... They just add up when you buy as many as I do....lol.

 

[shp1255]

The LOC Door Knob is a great flyer and perfect for a stretch dual deployment project. I had the same idea as you except I upgraded the motor mount to 75mm and added a bulkhead for zipperless drogue deployment. My version ended up being over 7ft tall because I added one and a half sections of airframe.

 

[qquake2k]

Nice launch photo! I love the paint job, too!

 

[neond7]

Finally some free time to play with rockets. First I trimmed about six inches from the payload tube so the rocket wouldn't be too long. Then I measured out the one layer 5.8oz and one layer of 3oz fiberglass. After applying both layers to the payload bay and switch band, I applied a wrap of Teflon peel ply. It's now curing. In a few hours I will remove the Teflon peel ply and trim the overhang while it is still green and easy to cut.

 

[CarVac]

Finally some free time to play with rockets. First I trimmed about six inches from the payload tube so the rocket wouldn't be too long. Then I measured out the one layer 5.8oz and one layer of 3oz fiberglass. After applying both layers to the payload bay and switch band, I applied a wrap of Teflon peel ply. It's now curing. In a few hours I will remove the Teflon peel ply and trim the overhang while it is still green and easy to cut.

Is that peel ply or release film? Peel ply is more like floppy cloth than what your pictures show...

 

[neond7]

Is that peel ply or release film? Peel ply is more like floppy cloth than what your pictures show...

You are correct, it is porous Teflon coated release film. I like it since it flattens out the seam and usually leaves a good surface ready for light sanding and primer. As long as you don't have any wrinkles.... I think I have a few, I'll find out in a few hours.

 

[CarVac]

You are correct, it is porous Teflon coated release film. I like it since it flattens out the seam and usually leaves a good surface ready for light sanding and primer. As long as you don't have any wrinkles.... I think I have a few, I'll find out in a few hours.

Hint: pull them out now before it hardens.

 

[gerbs4me]

Sweet project, looks like its coming along nicely. What electronics are you gonna be using?

 

[neond7]

Sweet project, looks like its coming along nicely. What electronics are you gonna be using?

I'll be using dual PerfectFlite SL100's, with a dual altimeter wiring kit from Doghouse Rocketry. Now that I have the switch band glassed, I'll epoxy it to the av-bay tonight and get started on the wiring.

I've been tempted to try the RRC3, but since I've been having 100% success with the SL100's its hard to justify a change. Plus I have already invested in the USB connectors for downloading data - so unless I get into air-starts or other fancy stuff, I'll stick with what I know. I probably have about 15 of them at this point as I don't switch sleds between rockets.

 

[neond7]

Ok, I may have reached my first stumbling block on this project. This is my first 7.5" avionics bay, and the stiffy coupler is much thicker than I'm used to - much thicker the 5.5" and smaller bays I've previously built. Normally I use removable nylon push rivets to hold the av-bay to the payload tube. I'm pretty certain the thickness of the coupler will preclude the use of these rivets.

Anyone have suggestions of a better method? This is my heaviest rocket so far, so it will need something a bit heavier duty to prevent the sections from coming apart at main deployment.

 

[qquake2k]

What about 2-56 or 4-40 nylon screws?

 

[neond7]

What about 2-56 or 4-40 nylon screws?

I'll use three 2-56 nylon screws to hold the nose cone on (and shear for main deployment). I'm looking for a way to hold the bottom of the payload bay to the top of the av-bay so it won't come apart.

I'll probably find some backing nut and use metal screws. That should hold it together - maybe someone has some pictures or McMaster Carr part numbers of the best parts to use.......

 

[qquake2k]

McMaster-Carr should have different length rivets. I would think they'd have something that would fit.

 

[pshooter26]

I would/do use Tee Nuts with button head screws.
Tee nuts with the paper tube so you get a little bite from the prongs of the nut.
On glass tubing I use just plain nuts or weld nuts (or fold or cut off the prongs of tee nuts if I dont have the formers).
Button heads cause they look a little cleaner IMHO.
Ive kinda stopped using rivets, maybe because it seems to be a pain to get my fat fingers under the head to remove them.
That, and maybe the last time I used an implement of destruction under the head only to have it go skating across the paint job.

As far as size, I tend to go overboard. Last 7.5 bay I used 1/4 -20.
But to give you an example, someone gave me a 10" Polecat Thumper. The avbay was held to payload with (4) #6 screws.
I couldnt believe it would hold together, especially with the 10+ lb nosecone yanking on the other end.
But given proper deployment setup, # 6 screws worked for many flights.

I still would have used larger.

 

[Getmore]

I use 10-32 tee nut from ace hardware. I have 3 on my 6" glass rocket. cardboard you might want 4. I call them blind nuts look at the screws in the two halfs of wood circles, that is what you want on the inside of the coupler.

 

[neond7]

I use 10-32 tee nut from ace hardware. I have 3 on my 6" glass rocket. cardboard you might want 4. I call them blind nuts look at the screws in the two halfs of wood circles, that is what you want on the inside of the coupler.

Perfect, thanks Bill. I'll check out ACE tonight, it's close to my house.

I'll definitely install four, it's a heavy rocket and overkill is the way to go.

 

[gerbs4me]

Are those SL100's user friendly? I'm looking for something easy setup

 

[grouch]

Are those SL100's user friendly? I'm looking for something easy setup

About as easy as it comes. You can literally take one out of the package, hook it up and fly it assuming you are happy with a 700' main. I love, repeat LOVE mine and will gladly buy another for my next dual deploy rocket. You seriously can't miss with one.

 

[gerbs4me]

Thanks for the advice... I will definitely take this altimeter into consideration when it comes time to get one...Thanks again

 

[Getmore]

What he said. I got 5 of them love em.

About as easy as it comes. You can literally take one out of the package, hook it up and fly it assuming you are happy with a 700' main. I love, repeat LOVE mine and will gladly buy another for my next dual deploy rocket. You seriously can't miss with one.

 

[AHansom]

Anyone have suggestions of a better method? This is my heaviest rocket so far, so it will need something a bit heavier duty to prevent the sections from coming apart at main deployment.

May not be a better way but my 7.5" Polecat Thumper the instructions said to glue the payload bay to the av bay. The Thumpers has a fairly short payload section so changing ejection charges is no big deal but if it was another 6" longer it might be a problem.

 

[shp1255]

I have been using PML Reusable Plastic Rivets to retain removable av bays in 3" diameter airframes up to 7.5". My stretch door knob posted above in the Oct 18th entry employs six rivets on each side of the av bay. I have found that the easiest way to remove them is with a thin knife blade to lift the head from the airframe; the you can get you fingernails under to pop it out.
As for the altimeter, I have been using Adept22 altimeters with great success. They are fairly easy to use and probably the least expensive which allows me to use two (redundancy) in my 5.5" & 7.5" rockets.

 

[neond7]

Status report - it's been awhile.

Last night:
1. Epoxied switch band to av-bay.
2. Applied Aeropoxy light to dimples in payload bay.

Today:
1. Used thin CA to coat outside of av-bay.
2. Used thin CA to coat 7" of the inside of payload bay.
3. Sanded down Aeropoxy light using finishing sander.
4. Primed av-bay with Duplicolor high build primer.

Still amazed the PerfectFlite manual recommends four .5" sampling port holes. I drill a 1/2" hole for the rotary switch. Seems to be a HUGE port.....

 

[Getmore]

Don't do that Jeff. I use the head phone jack hole that is my switch and then I drill 3 - 1/4" holes so I have four 1/4" holes around the av bay.that is all you need on a 6" BT or even 7.5 BT is plenty. You can go with 3/8" if you like but I would not do 1/2" holes.