LOC Photon Build.

[Back_at_it]

With winter here in Chicago I've slowed a bit with my builds but I feel like I want to do something for 2023 to kick the year off right. On a recent trip to LOC I picked up a couple of their smaller kits as well as a couple of the 5.5 models and I feel like it is time to do something.

I should mention that this is the second one of these I have built and I learned a couple things on the first build that I'm going to incorporate here.

Kit includes the following.
- Plastic nose cone.
- 1.9" cardboard body tube.
- 24mm motor tube.
- 1/8" plywood fins.
- 1/8" Plywood centering rings.
- Kevlar leader and shock cord. These look to be 200# but I could be wrong.
- 15" Nylon Chute.
- Fire Blanket. (This isn't listed in the kit description but mine had one.)
- Screw Eye.
- 1/4" launch lug and 10/10 rail buttons (not shown)
- White Vinyl Photon decal.
https://locprecision.com/products/photon
https://cdn.shopify.com/s/files/1/0568/7489/3503/files/Photon-Instructions.pdf?v=1623501248




To begin the build, I removed the outer layer of the motor tube. I scored along the spirals and peeled the shiny outer layer off. Afterwards I went over the tube with some 100 grit sand paper just to rough up the fibers a bit. The upper centering ring had the hole for the shock cord enlarged slightly and the inner and outer edges beveled for easy installation.

These pieces were glued together with TBII. While LOC recommends building their kits with Epoxy, This will be a low to mid power flier for me and honestly I Doubt it will ever see anything stronger than an E20 so wood glue is plenty strong.



The instructions give you options on where the upper ring is placed. Some choose to place the rings directly on the top and bottom of the fin tabs. I chose to install the upper ring at the very top of the motor tube so there was less volume for the motor to pressurize and it moves a little weight forward. Using TBII, the upper ring was installed and a fillet was placed around the top and bottom of the ring.

Next I installed the Kevlar leader using the shorter piece of Kevlar. The instructions tell you to install this using the screw eye threaded into the upper ring. I chose to remove the screw eye and simply tie a knot in the Kevlar line. The line was then slipped through the hole in the upper ring.



The motor mount was then flipped upside down and the knot was covered in TBII glue. An additional fillet was done under the ring as well.



That is as far as I got this weekend. I did sand the fins and do some additional prep work but you guys will see that as we progress.

 

[Hobie1dog]

you are starting out great by supplying lots of pictures, thanks

 

[Back_at_it]

More progress on the Photon.

I added a 5" piece of shrink tubing over the lower part of the Kevlar for a bit of additional protection from the ejection. I then made a loop in the end of the Kevlar where the shock cord will attach and added a drop of TBII to the knot to keep it secure. At this point the Kevlar was tucked down inside the motor tube and the motor mount was inserted into the body tube.

NOTE that the lower ring is not glued in place. This was left off to allow for internal fillets. It will be temporarily inserted while the motor mount dries to keep the tube aligned.



With the motor mount completely cured I started with the fins. The sides of the fins were a bit rough so each was sanded with 120 then 320 grit to smooth them out. This will make for easier finishing later. The edges of the fin tabs were also rounded slightly to allow them to be inserted a bit more easily. Starting with the a lower fin, Each was attached using TBII.




Next was one of the smaller upper fins. These too were sanded prior to install. Due to their size, they attach easily and aligning them with the lower fins was easy.



From there it was just a matter of attaching each of the fins. Everything fit together perfect.



Next up will be doing internal fillets. Going to be a little tight in there so I'm thinking the syringe method will be the way to go.

Thanks for following along.

 

[Back_at_it]

Long work day yesterday so I didn't get as much done as I would have liked.

Did internal fillets using TBII. Tried using a syringe but it was just too tight. Ended up using a thin paint brush and dipping it in glue and just brushed it on where the fins attach to the motor tube and the inside of the body tube. Did two coats so I'm feeling pretty good about them. Kind of made a mess but it's all internal so it will never been seen again.



Once the fillets were dry I cleaned up the motor tube and knocked down any large spots of glue that would get in the way of the rear ring. The rear ring was then installed with TBII.



Next came the motor retainer. This is the Estes 24mm motor retainer. The inside was sanded to rough it up before wiping with rubbing alcohol. BSI 30 min epoxy was used to attach the retainer.



Next came launch lugs. LOC provided both a 1/4" card board lug and 10/10 rail buttons. Since this is a light weight rocket that will only see mild motors I elected to use a 3/16" lug. The lower lug is 2.5" long and is attached 1.5" from the bottom of the body tube. The upper lug is 2.0" long and was attached 7" up from the bottom of the tube. Both we angle cut for ascetics.



Next it was time for external fillets. These will be minimal. The strength is all inside so these are really just to seal the fins to the body. This was done with TBII.



After the fillets dried, I hit the lower fins with DAP wood filler. The grain of the fins are very smooth after sanding so one light coat is all that is required.




From here I'm going to deviate from the normal build. I want to add a payload compartment for my altimeter and to stretch the body a little. My previous Photon needed nose weight to be stable on E12 motors so I ran some sim's and found that a three inch payload bay will correct that regardless of which motor I choose.

 

[Back_at_it]

Decided I wanted to add a payload section to the Photon to both give it a little more length for stability and have a separate place to store the altimeter. My previous Photon needed nose weight to be stable on E12 motors so I figured adding some length would accomplish both goals.

I started with a LOC 1.9" coupler. A bulk head and the original screw eye that was provided with kit. A .50" piece was cut from the coupler.



First step was to glue the piece I sliced off inside the coupler. This will give me a positive stop for the bulkhead and prevent any possibility of it pulling out during ejection.



Next I assembled the bulkhead. I did add an additional piece of scrap plywood to the back of the bulkhead so the screw eye had a little more the thread into.




Next the Bulkhead was glued into the coupler. Once dry the coupler was flipped over and fillets were applied.



Next I cut a 3.5" section of body tube for the payload bay. For this I'm using epoxy as I want to test out coating the exposed section of the coupler for strength.

I lightly sanded the outside of the coupler. I then marked the coupler approx. where I wanted to stop, mixed up a small batch of BSI 30 min epoxy and spread it over the inside of the body tube and the outside of the coupler then inserted the coupler.



Typically I coat my couplers in thin CA for strength and it helps them slide smoothly into the body tubes but a recent conversation with Jason from LOC, he suggested I try Epoxy. I figured this would be a good place to learn before trying it on a larger project.

The excess epoxy was spread over the exposed lower part of the coupler as well as the inside of the top of the body tube. Once spread evenly, I used a heat gun to warm the epoxy to make it thinner. After letting it sit on the surfaces for about 3 mins, I used a paper towel that was slightly damp with alcohol and wiped away the excess then let it cure for a few hours.

My sanding of the coupler created some fuzzies that needed to be knocked down after it cured. I hit the exposed area with some 320 grit to knock off the high spots. The good news is the epoxy worked. The exposed portion of the coupler is now rock hard with an almost plastic like feel.

 

[Back_at_it]

Made good progress on this one over the weekend. Starting with the nose cone. I cut a bulkhead to fit up inside the nose cone. This is made from 1/8" hobby plywood. This will sit just above the shoulder of the cone. The rear of the nose cone was removed, the inside was sanded then washed before attaching the bulkhead with BSI 30 min. epoxy.





I'm using a small piece of Kevlar attached to the nose cone just in case the nose cone comes loose during flight. There will be no ejection pressure up here and the cone will be friction fit but Just in case it comes loose, we have a small tether to keep it from getting lost. This was attached to the inside of the tube using the old Estes tri-fold mount then tied to the nose cone. Also gives me a place to attach the altimeter.




Here I attached approx. 5ft of 3/8 elastic to the Kevlar leader and the base of the payload section.



First pick of the final assembled rocket.



Weather played nice just long enough for me to get a couple coats of primer applied.



Here we are after sanding. At this point it's ready for the final coat of white primer then paint.




Weather is forecasted to be in the 40's here today so I should be able to get the final coat of white primer on. After that we might have a waiting period as mother nature will dictate when I will be able to to paint.

 

[Back_at_it]

Picked up a new color at HL this week. When I saw the color I knew I wanted it for this project. The color is Krylon Foil Metallic Blue.

Monday I was able to shoot on two coats of white primer and let it dry. This morning I shot on the first coat of Krylon. That was left to dry for about 4 hrs. It was dry to the touch in about 15 mins. After 4 hours I sanded with 600 grit then applied the second coat. This has been sitting for approx. and hour. The metallic doesn't come through in the pic. The flakes are huge and the color is beautiful and bright.

Still have a couple of more colors to apply but I'm going to let this cure for a couple of days.

 

[waltr]

I like that color.
It will be nice and bright in the sun.

 

[Scott_650]

Really looking forward to seeing this one finished in a scheme different than the face card - the face card scheme is very unattractive to my tastes. That blue metallic is looking good!

 

[techrat]

You're going to launch a blue rocket into the sky? Good luck spotting that one. Although to be fair, it seems that all rockets look black against the sky on a sunny day.

 

[Back_at_it]

You're going to launch a blue rocket into the sky? Good luck spotting that one. Although to be fair, it seems that all rockets look black against the sky on a sunny day.

I don’t typically fly high enough that the rocket is out of sight. I like most flights to be in the 1000ft range. I can typically keep track of small rockets (Alpha size) up to that altitude without too much issue so something this large should be easy.

Also, the metal flake in this paint is so bright that it flickers in the sun like chrome. I also buy brightly colored parachutes and occasionally attach a foil streamer if I know I’m breaking the 1500ft mark.

 

[Hobie1dog]

four fins and a beautiful blue paint job

 

[Back_at_it]

Did a couple of last minute items while the paint was curing.

Assembled the included 15" parachute. While I probably won't use this chute on this rocket due to it's white color, It is a nice chute that appears to be made from Nylon. The chute comes with a single length of cord that needs to be cut into three equal lengths. The instructions then have you thread the line through the holes in the chute and tire knots to keep them in place. I added a drop of wood glue to each knot to keep it secure. While I'd like to see an assembled chute with this kit, I understand that they need to sell at a price point.

Once completed I added a clip to make the chute removable.





Final assembly began with attaching the nose cone to the payload section. The Kevlar was tied in place with a drop of wood glue. Tape was added to the shoulder until the fit of the nose cone was very tight.



Next it was time to attach the payload section to the main body. Here the elastic was tied to the eye hook with a drop of glue.



And finally..... It's done. The nose cone was painted in Duplicolor bright white. The fins and the strip around the top were painted using Krylon glass black.




I still need to get a finished weight and CG measurement to plug in OR. I'm also going to get some picks of this color out in the sun. Today is a rainy wet day here so that will need to wait for another day.

 

[Scott_650]

View attachment 557455

Next it was time to attach the payload section to the main body. Here the elastic was tired to the eye hook with a drop of glue.

View attachment 557456

And finally..... It's done. The nose cone was painted in Duplicolor bright white. The fins and the strip around the top were painted using Krylon glass black.

View attachment 557457
View attachment 557458

I still need to get a finished weight and CG measurement to plug in OR. I'm also going to get some picks of this color out in the sun. Today is a rainy wet day here so that will need to wait for another day.

Very nice! Again, not beating up the folks at LOC, but this color combo is light years better than the yellow/black on the face card and website. Only thing I’d probably do different is a red nose cone, I generally like a bit of something bright and contrast-y on 3/4FNC designs. Looking forward to seeing the final weights and glamour shots.

 

[Back_at_it]

Very nice! Again, not beating up the folks at LOC, but this color combo is light years better than the yellow/black on the face card and website. Only thing I’d probably do different is a red nose cone, I generally like a bit of something bright and contrast-y on 3/4FNC designs. Looking forward to seeing the final weights and glamour shots.

Scott, funny you should say that. For a while I had a red nose cone on the rocket in OR and was going to go with that color. Then changed my mind and was going to go with a metallic gray but in the end, white won out.

As much as I like the white, the metallic gray might go on a spare nose cone and get swapped in.

 

[Back_at_it]

Back with one final update until a flight report which looks to be a couple of months off at this point.

Final weight complete with all recovery gear, wadding minus the motor is 226 grams or 8.0oz.



With all recovery gear and the heaviest motor I plan to fly (E12-6) in the tail the measured CG is 19.5 inches from the tip of the nose cone.



Plugging this all into OR I come up with 1.79 cal. So it's plenty stable with anything I want throw in it.



Looking at some of my commonly used motors, this will make a nice small park flier on a D12-5 around 430ft and decent altitude on the E12-6 around 840ft. I can always go for a composite if I feel the need for more.

 

[waltr]

Or go with composite E motors to avoid Estes E CATOs.

 

[Back_at_it]

Or go with composite E motors to avoid Estes E CATOs.

Never had a CATO on any Estes E or F motors. I know they happen but in the hundreds and hundreds that I have launched I've never had one explode. I have had a failed ejection but that happens to every motor from time to time. Interestingly the A10 is the only Cato I've ever had.

 

[Scott_650]

Never had a CATO on any Estes E or F motors. I know they happen but in the hundreds and hundreds that I have launched I've never had one explode. I have had a failed ejection but that happens to every motor from time to time. Interestingly the A10 is the only Cato I've ever had.

As much as I take anecdotal info with a grain of salt my experience has been the same - even the dozens of E9s I used in my early BAR years worked just fine. My only true CATO was an Aerotech G77 - turned my 4” crayon rocket into an awesome flaming wreck! I did have a C11 that went into rapid burn through mode - my rocket cleared the rail, hit about a 20 foot apogee then landed on someone’s truck, no damage to the rocket or the truck

 

[Back_at_it]

As much as I take anecdotal info with a grain of salt my experience has been the same - even the dozens of E9s I used in my early BAR years worked just fine. My only true CATO was an Aerotech G77 - turned my 4” crayon rocket into an awesome flaming wreck! I did have a C11 that went into rapid burn through mode - my rocket cleared the rail, hit about a 20 foot apogee then landed on someone’s truck, no damage to the rocket or the truck

If you look at CATO's there seems to be two groups. People that have CATO's and people that don't. There doesn't seem to be a middle ground. And, it seems like those that have them seem to have a lot of them. It would be interesting to seem of there is some common denominator that we could identify. Is it a geographical, temperature, handling, storage etc.

In 35 years and around 4K flights I've had one. And that was the first one I had ever seen in person.

 

[waltr]

If you look at CATO's there seems to be two groups. People that have CATO's and people that don't. There doesn't seem to be a middle ground. And, it seems like those that have them seem to have a lot of them. It would be interesting to seem of there is some common denominator that we could identify. Is it a geographical, temperature, handling, storage etc.

In 35 years and around 4K flights I've had one. And that was the first one I had ever seen in person.

That is the most likely answer.
These larger BP motors do not like wide temperature swings or rough handling so storage and transportation is important.

At local club launches we seem to get 10-15% of BP E's & F's CATO.
At the last MDRA launch it was nearly 100% CATO on these motors.

I three years of going to launches I have seen quite a few CATO.

 

[artgsc]

Excellent build thread and thank you! One question if I may....It appears that you don't worry about rounding the leading edges on your fins….Can I ask why not?

 

[Back_at_it]

Excellent build thread and thank you! One question if I may....It appears that you don't worry about rounding the leading edges on your fins….Can I ask why not?

Biggest reason I don’t do it on most smaller rockets is that I’m not looking for altitude. I like to fly where I can see the rocket. For something this size, I figure that will be something under 1500 ft.

On larger rockets I do tend to bevel the fins as the wood is thick. On some rockets like my Warlock, you could get into drag separation issues so keeping things smooth at the back of the rocket helps.

Lastly, on some rockets I feel the square edge works better with the design.