1/4 Scale Viking 7 sounding rocket

[GalantVR41062]

I have decided that I have rockets in the build pile that will go super sonic, and run up close to the 20,000' waiver at the local Tripoli high power rocket launch site in North Branch Minnesota. I also have a 1/2 scale SLS ARCAS that I built and fly, the only thing out of place are the launch lugs, vent holes, screw on retainer, and no air foiled fins.

I also could do some larger motors in MD projects and push the limits with L's and go to Kloudbusters.
I also watched a few youtube videos of large projects flown here in MN: Old Yeller, scale Nike, Good Enough. I am inspired by maximum performance multi stage projects but my rocketry budget can not support those ambitions so I am going to go down this path and see where it takes me.

I feel I have a lot of room to grow into the L2 motor line up and I need to learn a lot more to justify the L3 dedication, I am on the path to get it at some point.

For my current OR files I have focused on making the air frame as accurate as possible out side dimension wise to get a more accurate CP location, then I can deal with the CG and total weight out side the simulation. I just started my HP rocket flying in 2017, I flew rockets with my Dad years ago, nothing larger then a C though.

I like the accurate recording or flight data, pictures, video from the ground, at the pad looking up, onboard video, a straight column of smoke rising into the blue sky, going by a few clouds on the way just like the final flight from October Sky as viewed from the hospital room.

I promise there will be a build thread in here somewhere.

Then walking through Home Depot racing, I come from a automotive background and making them go fast, and see concrete form tubes and like any other BAR I started thinking of how I could turn all things into something rocket related. The 8" form tubes were calling me as to itch the how big could I make it part. I was able to hold off on buying parts for a while but gave in this summer.

I will start with a over view of the project, what I think it should be and my plan to get there. I could use help in processes, technique, scale details, fin flutter, a more complete model and simulation with Open Rocket, mainly rail guide length, wind, simulation of chutes to be used and decent rates.

I don't know how but I stumbled on the dimensions and design of the Viking 7 sounding rocket. I then figured out I can do a 1/4 scale version with 8" diameter tube, 143" tall, 4 fins with a fin span of 27.5", with the "Tab" on the fin corner.

I pulled the wax layer from the inside of the tubes and plan to sand the outside. I am going to double layer the airframe, I will cut a strip out of the 8.325" od tube and glue that to the inside of the 8" od tube.

I will have the inner tube stop 8" before the top of the booster and start 8" into the payload so the coupler will sit on the inner tube.

I also double walled the coupler, and the av bay lids will sit down inside the coupler on top of the inner tube.

I am going with a 98mm mmt and have a 98mm Slimline retainer.

I have 1/2" plywood to cut centering rings, and make the fins, do a layup of fiberglass or figure out stronger material if needed.

I will be making the nose cone as well, it's only a 2.6:1 so I will make a plywood x structure and hobby foam pizza slices to make up the shape. Then fiber glass over the top. I will have a spot in the nose for a tracker and room for weight, up to 50-60oz and a HD video camera of some kind.

OR and thrust curve are showing a all up weight of 55lbs with a 98mm L, it could fly on a 54mm AT K1275 est 1150' apogee. The AT L1500T or AT L2500ST will be what I am building this for, looking at 3700'.

It will be dual deploy, with a large drogue and main chute. I loaded up the OR file also, I did find the spot to adjust the launch parameters.

~John

 

[GalantVR41062]

More pictures and the start of the building process.

I show the fin tab in the OR file but I think I will make them removable so the fin is less likely to be damaged during recovery.

The paint scheme is fairly simple white and black so I will try to mimic that the best I can.

I have been picking up parts in the yard sale and other places, I will gather all I have and update with another large post outlining the build material, recovery components, electronics etc.

~John

 

[GalantVR41062]

I was working on the booster section. I have the tubes cut to length, wax peeled and I just need to start gluing the air frame together.

I was test fitting the 4' inner section that will connect the lower and upper tubes making the 6' booster and my cut was not very straight and not wide enough so the tube became stuck.

After a while of trying to pull it out I ended up stepping on it and it tore on the spiral seam and I pulled it out.

I learned the tubes are not that strong in this area and the coupler I made being double layer the seam does not line up and the structure feels a lot stronger. So as I glue the other split tubes into the 8" OD tube I will look to make sure the seam does not line up.

I then marked 1/2" up the inside of the bottom booster tube and glued the 24" section inside the bottom of the tube. Next I will glue a 38.875" section, then the 24" top tube to make the complete booster tube.

I also glued the 2.625" wide switch band onto the coupler.

Here are a few pictures of the parts I have been gathering: 1/2" plywood, I will look at aircraft quality plywood for the fins, but this 1/2" interior plywood will work well for the centering rings, bulkheads etc. I have a jigsaw I bought and will either make or buy a hole cutting fixture for it. I also have some thin wood strips if I feel the need to brace between the mmt centering rings and or make fin tab pockets. I did buy a whole gallon of TB2 wood glue, I will be using a lot on this project. 98mm Slimline retainer.

5/8" tubular Kevlar, 5/8" tubular nylon, nomex squares, drouge: 144" sphere chute, main: Skyangle Cert 3 XXL, copper caps and pvc caps, I have a hand full of electronics and will use a ARTS 2 altimeter, and a MW RRC2+, MW T3 GPS tracker, and or Communication specialist RF tracker. I plan to split the airframe in the middle at apogee, and backup at +2 seconds, then main at 1000', and backup at 800'. The payload tube will be attached to the eBay lid with SS screws, 8 total, and I will use 3-4 nylon sheer pins to hold the nose cone on.

I will do a Kevlar Y harness off the mmt to a HD swivel, then the 5/8" tubular nylon 36', then another section of Kevlar, about 2' hooking up to a 3/8" SS U bolt on the eBay. The drogue will attach 8-10' down from the ebay, the main will attach to the quick link on the nose cone end of the main harness. I will be getting 2 deployment bags.

The main will also have a Kevlar harness, 6' long, hooked up to a 3/8" SS ubolt on the top of the ebay. Then another section of 5/8" tubular nylon, 36', that will attach to the nose cone base with another 3/8" SS ubolt. I will use my sewing awl to stitch the loops together. And use 3/8" SS quick links into the booster, eBay and nose cone.

~John

 

[GalantVR41062]

I started on the nose cone base. I cut a 10" length of the tube that fits inside the 8" od payload tube, then glued a piece to the in side of that making it flush on the bottom.

I then glued a 2" chunk of the 8" od body tube towards the top of the nose cone base, having 8.125" slide into the payload tube, the same for each end of the Ebay coupler. This will be my transition for the 2.6:1 nose cone. I also cut out a cardboard mockup to slide into the nose cone base.

I also took a stab at the dimension on the fin tab sticking out of the bottom corner or the fin and cut a cardboard mock up, then setup the rocket to get a feel for the scale, and looks so far.

I will be setting up to cut centering rings and bulk heads this week. I will do research on the size of the recovery mounting gear, but I am thinking: 3/8" SS U bolts (2) for the booster mounts, then a single 3/8" SS U bolts for the Ebay bulk heads, and nose cone base.

I have updated the OR file with a more scale version of the fins, based on the pictures or the actual rocket, and the pictures of the model rockets available on the market. The Fin tab is a little higher up, and a notch on the trailing edge of the fin. In the pictures the outboard edge does not look to run parallel with the air frame, but angles out slightly.

I will keep looking at pictures and try to figure out the external details on the rocket and add them the best I can.

~John

 

[GalantVR41062]

I was able to get the main body tubes glued together, I had to add 1 1/4" to the inside of the payload tube as I somehow missed the mark for the length on the inner tube to have the Ebay lid and nose cone base sit on the inner tube.

I stacked about 100lbs on top of the booster tube as the glue setup. I have used 3 TB2 squeeze bottles so far.

I will be adding a 1/2" thick plywood centering ring to the top of the booster tube to help the structure stay in shape over time and flights. It will be about 3/4" wide and sit on top of the inner tube.

I trimmed the card board fin mock up for the updated OR file.

I also started cutting the pieces to make the nose cone structure, 1/4" thick ply wood. I need to sand to shape, cut some holes, setup 2 nose cone compartments and start cutting hobby foam pizza slices to make the shape to be covered in a couple layers of fiber glass. The 2 compartments will be in the nose cone shoulder area opposite each other in the X structure. One will be for GPS or other tracking solutions and the other will be available for other electronics or video down the road.

I marked and started cutting centering rings, I need to cut the hole for the 98mm mmt, and sand to fit the rings, bulk heads.

~John

 

[gna]

Wow, very impressive. I like the Viking, rockets, too, so I'd like to see this one fly.
I made a LPR Viking 7 a couple of years ago, and had an OR design for an MPR one using an Estes Partizon:
https://www.rocketryforum.com/threads/viking-7-first-scratch-build.129512/
https://www.rocketryforum.com/threads/viking-7-sounding-rocket.129350/

I eventually found a copy of Milton Rosen's The Viking Rocket Story, which is interesting and not at all technical.

 

[GalantVR41062]

Thank you. I did find the 2 threads you linked when I started research on the viking 7, that and seeing others work with sono tube I figured out the 1/4 scale option for the viking 7.

There are a few more months of winter here in Mn, I could have this flight ready early in the rocket season.

I have the AT 54/2560 motor
Ellis Mountain 75/7000 snap ring motor
Options to loan 75mm CTI hardware

I will save money to get a AT 98/5120 motor

I will be going to menards later today to look at the aircraft 1/2" plywood to make the fins.

~John

 

[Ez2cDave]

 

[GalantVR41062]

I finished cutting out the MMT centering rings, interior spacer rings and bulk heads.

Now I just need to true up the OD of the CR's then mark and cut the hole for the 4" shipping tube that will make the first thick layer of the MMT, they are 24" long and I have a 4" x 31" MC body tube on order to make it the 3.9"/98mm MMT. I also picked up a 75mm mmt to make an adapter.

I also started gluing the nose cone structure together, then I will sand to shape and glue into the nose cone shoulder.

I glued a ring in the bottom of the payload tube, the Ebay lid should sit on the ledge, I will make all the attachment points and charge wells smaller then the 6" hole in the ring. I realized I could not do this to the top of the booster or payload tube as the recovery gear would have an issue coming out.

So I will do a layer of fiberglass on the top inside of the booster and payload tube. This will help fill the gap from the ebay and nose cone shoulder, and help with the nylon shear pins as well.

I decided to glue the bottom bulk head into the ebay coupler, I figured this would make for a more ridged anchor point as the rocket separates at apogee and descends on the large drogue.

The payload tube will come off the ebay with some screws and the top lid of the ebay will be removable to gain access to the electronics

Thank you for the photos they look amazing.

~John

 

[GalantVR41062]

I was working on the nose cone, cut and fitted a few bulk heads, made a centering ring that the bottom bulk head will bolt to, making a large area for nose cone electronics with no threaded rod to affect GPS or RF tracking.

I cut 4 slots in the top of the nose cone base, slid the x structure in and spun it in the lathe at 70rpm, it looks fairly symmetrical.

I started to cut the foam wedges, then I will use construction adhesive to hold them in place for the fiberglass layup on the outside.

I also cut one of the 24" 4" shipping tubes so I will have a total of 42" of motor mount tube, then the 31" body tube will be glued inside these, with about 3/4" sticking out to attach the 98mm Slimline retainer.

I also updated the OR file to reflect the changes in the nose cone.

~John

 

[Ez2cDave]

Dave F.

 

[GalantVR41062]

I cut the 4" shipping tubes to length and glued the 31" long 4" mmt inside. It almost made it to the mark but stuck, so I had to cut 1.5" off the bottom of the inner mmt. I needed 3/4" sticking out for the slimline retainer to sit in a 10ga aluminum thrust plate I will fabricate and attach to the aft CR.

I think I will be doing 4 aluminum threaded rods to go from the thrust plate to forward CR, I can tie in the 2 U bolt anchors to distribute recovery loads to the majority of the lower air frame.

The fins will be through the wall and I will be making a trough for the fin root to sit in on the MMT. I am still thinking the process on MMT assembly and instillation, I plan to glue and fillet the CR for the top of the fins, and the one in the middle top of the MMT, this would leave the top and aft CR off for interior fillets etc. I will try and plan to add the threaded rod after the MMT is glued, but before the forward and aft rings are glued in.

I have been cutting foam for the nose cone shape and hope to be getting into fiberglass work this next week.

I cut the 4 fins out all at once, minus the fin tab detail, I then used the jigsaw for the detail cuts. I am happy with the look and shape. I will be doing a simple airfoil shape for the fins, and am leaning to cutting the fin tab off, then fabricating aluminum airfoiled fin tabs that bolt on and are adjustable for the scale look, or try them to help with the roll of the rocket if its predictable.

I made some more adjustments to the OR file, I have the rocket setup for dual deploy and single deploy for the smaller motors, the stability was high at 2.8 calibers on the AT K1275R motor. Adding a 54mm reducer for the MMT and moving the main to the booster and just have it single deploy with a JLCR if I feel I need to delay the main deployment, other wise the deployment bag and a slip ring on the main shroud lines could help get things deployed smoothly and moved the CG back to 2.2 calibers of stability. I think the 2.8 calibers of stability on the AT L1500 and L2500 will be alright as the motors will be hitting a little harder and getting it up to speed, is there a issue with running this high of a stability margin at subsonic speeds?

I also removed the fin tab on the single deploy and it looks like that will move the CP and result in a 1.7 calibers of stability on the smaller motors.

~John

 

[GalantVR41062]

I decided to use 1/4" zink coated steel threaded rod. It was cheap, available at Home Depot and will help move the CG back a little.

I used the rods to mock up the rings, and glued the 2 centering rings in the middle. Leaving the top and bottom rings removable for now.

I used my electric drill to thread the first nut to the middle, then did the others by hand. I used super glue to lock then into place. And tightened the nuts down on just the middle 2 rings putting the rods into tension a little. I secured the inside nuts for the top and bottom rings with super glue and just need to tighten the outside nuts once the top and bottom. Rings go on for the last time.

I then marked the booster tube with the locations of the centering rings. I did this so I could tighten a strap around the ring as the glue dries, and I plan to run a few wood screws into the centering rings.

I stood the booster up, slid the mmt in and covered 2 centering rings with a lot of wood glue and pounded the motor mount into place, then cinched down the aft ring to help hold things square and at the right depth.

I will be doing a wood block backer for the 1515 rail guides I have. Just above the aft ring, and just below the top ring. I will be attaching the 2 5/16" SS U bolts to the top CR before I install that. I will use construction adhesive on the body tube and mmt when installing the top and aft rings, then use wood glue on the plywood ring OD and ID

I did sand the nose cone plywood structure to shape, and I might make a solid wood nose cone tip, this would help to have a nice shoulder at the base, and the tip to start/stop the fiberglass.

Up next: get the fins ready to install. Cut off the fin tab and airfoil the fins, mark fin slots and notch the booster tube, glue fins in, internal fillets, rail button mounts, top and aft centering rings install. Fiberglass nose cone and finalize recovery harness attachments. Start to plan out the Ebay.

I also had a friend take my picture standing next to the rocket mocked up again with the plywood fins and nose cone.

~John

 

[GalantVR41062]

It's been a while, I have worked on this on and off getting things done.

I worked on the top CR for the mmt, I installed 2 SS U bolts and have the all thread for the CR's going through the metal strap to help transfer the recovery load over all the CR's. I was able to get construction adhesive on the ID of the body tube and the od of the mmt. I also fabricated a aluminum strap 1/2" tall and 2" wide, notched the CR and drilled 2 recessed holes and screwed it into the CR. I will be doing this to the aft CR also then drill and tap the holes in the aluminum for the rail buttons to attach to.

I sanded a 2" wood dowel piece down into a nose cone tip, then glued that to the top of the x structure, after trimming a little to make a flat spot. I then finished the foam and wrapped it in masking tape.

Now onto the full part, I mixed up a hole can of bondo, about 1.8lbs worth and roughed in the nosecone shape with the new wood tip. Then used a cheese grater, then sandpaper to get it looking like a nosecone. After that I cut the heavy fiberglass mat material into some shapes to cover the cone, used 3m 77 adhesives spray to hold the glass in place then started mixing up the bondo resin. After the first coat I sanded and applied another coat, then sanded again. I still might have to blend up a little bondo to get it where I am happy. Overall the nose cone now weighs 6lbs.

I also took the top of the booster, and both ends of the payload and laid down 1 layer of the thick fiberglass and resin. This helped the 7 5/8" od tube slide into the 8" od tube snug, and I wanted the extra strength as the body tube is only 1 layer thick in these places. I then glued some heavy paper to the shoulders of the ebay and nose cone with a ring of masking tape to finalize the fit. I might come up with a more permanent solution down the road. For now the airframe together and holding it horizontally there is minimal sag at the connection points.

~John

 

[GalantVR41062]

I then made a slide ring with measurements on it to layout the fin slots and the RB location. I used a long chunk of angle aluminum to draw the vertical lines, then held a scrap piece of the 1/2" plywood centered and marked the slot to be cut.

I drilled holes in the 4 corners first then used the jigsaw to cut then out.

I had also taken the time to bevel the fins, and get them ready to glue into place.

I stacked up the ebay, payload and nose cone to see how they lined up and looked.

Then it was onto figuring out how to glue the fins into this thing as it stands taller then me and I did not want to lay it horizontally.

I did stack it all up outside after cutting the fin slots but it was to dark to get a good picture. The fins and nose cone sure make it look like something.

I decided to do a makeshift fixture to line up the 2 fins opposite each other, then used a ratched strap to pull them in tight after gluing the body tube, mmt, and fin root. I then looked at it visually and measured from the fin edges all around and it's about 17 7/8" on all 4 fins.

I will be doing internal gluing etc before the aft CR goes on for the last time. I will also be fabricating a 10ga aluminum thrust plate to go on before the Slimline 98mm retainer.

I will be doing big external fillets, I just don't know with what yet. I plan to fill the tube spiral with bondo.

I set the parts on the scale to see how its coming along. The booster weighs 20lb 10oz with the fins. The ebay, payload and nose cone weigh 14lbs.

~John

 

[GalantVR41062]

Here is the final full scale mock up minus the 2" or so square fin tabs (will be there for display or a N or O flight only, some day) I will be working on fabricating the removable and adjustable tabs in the coming weeks.

This is my aluminum 1010 rail pad with a 86" rail that I use to fly MPR at parks and frozen lakes on mid power motors.

I am installing 1515 rail buttons to fly with on a much larger pad with at least 120" rail length.

The next step is internal fillets on the fins, attach aft CR, fabricate aluminum thrust plate and install with 98mm Slimline retainer.

Then fill the spiral and start prep for paint. We have our first local launch 2 weeks from now, I plan to bring the rocket to show, and talk with the motor guy about getting what I need to get this project off the ground.

Then make the final plans for recovery, ebay layout, nose cone bay setup, patch the few holes in the used skyangle cert3 xxl main.

~John

 

[FredA]

No way that pad will take an N or O....
You'll crush the legs and flip it over with the sideways blast plate.

 

[Nytrunner]

No way that pad will take an N or O....
You'll crush the legs and flip it over with the sideways blast plate.

But it makes a good display stand for those that don't have a personal 1515 launchpad!

 

[GalantVR41062]

If it fits, it ships. I picked up a deployment bag from the yard sale, the SA cert3 xxl fitsish. I could play with packing more or watch some videos/ask at out next local launch the official way to do this.

I will use this deployment bag for the 144" sphera chute as it fits with plenty of room, the package slides in and out of the airframe with no problem.

Then get a larger deployment bag for the main, recommendations?


I worked on the recovery gear and ebay tonight. I have tnuts under the plywood ring and am using 4 1/4" 20 bolts to hold the end cap on. I installed the 5/16" SS ubolt also.

I was just barely able to reach the 2 ubolts in the top centering ring to test fit the 1/4" SS quick links. I will be making a kevlar y harness to attach here. I then have 3/8" quick links to attach to each end of the ebay and nose cone.

I have some large PVC caps for charge wells, I have some smaller ones if these are to big.

I am using 3 5/16" all thread to hold the ebay together, I have the 5/16" SS ubolts on both ends tie in with the one all thread towards the middle, then I have the other 2 to the edge, I drilled holes in the payload tube plywood ring that the ebay sits on, I also did a 1/4" 20 tnut on the other side of the ebay lid by the SS ubolt. So from the top I tighten the 2 nuts and 1 bolt to hold the payload tube onto the top of the ebay making it a very ridged structure that does not sag when layed horizontal.

I will be doing screws to hold the nose cone on when not dual deploy then figure out shear pins for the DD flights.

I will be adding 3/8" vent holes for the ebay and 1/8" vents for the booster and payload tube.
I did get the aft CR on, with a wood screw into each fin, and installed the aluminum piece on the side of the aft ring that I will drill and tap for the rail button mount.

I am going to make a 98-75 adaptor and cut the 10ga aluminum thrust plate with my plasma cutter, then epoxy that down, use the 4 1/4" 20 acorn nuts and then epoxy the Slimline retainer on.

I did a all up weight check, the rocket as a hole weighs 38lbs 10oz. I have 8lb 8oz of recovery gear and electronics for the single deploy flight. I adjusted the OR file for the actual weight and CG, looking like 47-48lb without a motor or paint.

~John

 

[GalantVR41062]

Everything is better with a plasma cutter, made quick work of the 10ga aluminum. Then some clean up and marked for the 4 holes the threaded rod would pass through.





I mixed up JB weld, sanded the aluminum thrust plate to be bonded to the aft centering ring, layed down the JB weld and tightened down the open nuts with a few washers on each threaded rod. I also prepped the 98mm mmt by poking some holes through it halfway down, mixed up some more JB weld and slid the 98mm Slimline retainer on, then stacked on some weight over night for the JB to cure.



I then took my sanding block and smoothed out the ID of the MMT and the edge around the base of the rocket. The retainer sits tight onto the thrust plate, and should handle the large L2 motors I plan to fly this on later this summer.



I was at Home Depot 2 weeks ago and they had a few cans of Navajo white spray paint, so I picked up 6, and a few cans of glossy black, and primer. I am sure I will need more primer but it's a start.

I have 60' of 1" tubular nylon in my shopping cart at wildman but not sure that its needed, or if the 5/8" tubular nylon I have will be strong enough. I will be sewing the loops etc, I might make a tri y harness to grab the ubolts in the top CR and a forged eyelet on the forward closure of the motors I will fly, I would have to figure out how to adjust for the different length motors.

I am debating on if I should fiberglass the fins or not. I feel I have to do something with the leading edge, and trailing edge of the fins to help with in flight and landing/hanger rash forces.

I seem to recall reading the recovery gear should handle 50g shock loads, that's 2500lb with this project. Doing research on the recovery attachment points: 5/16" ss u bolts and quick links 1950lbs, 3/8" threaded rod for the ebay 7000lbs, 3/8" zink coated quick links 2200lbs. So the single weak link in my recovery harness can handle about 36-40g.

~John

 

[ToneDeafJunior]

Now this is rocketry. I'm so impressed! Love the pictures in the thread.

 

[GalantVR41062]

Thank you all for looking and input so far, if there is any part of the project you have questions on or I have not covered fully let me know.

I have been working on the project a little here and there. More parts have showed up and I am working on the OR files for single deploy and dual deploy and my motor choices for a good safe first flight.

Running single deploy with the skyangle cert 3 xxl main in the skyangle XL deployment bag and a AT 75mm K1000T motor is showing a good rail exit velocity and apogee at 1400'. Low and slow, then the next flight could be a 75mm AT L1520T to about 2800'.

I am almost done with the 98mm-75mm it is a nice snug fit in the MMT and with my Ellis mountain 76/7000 case in there it's starting to look like a rocket.



I picked up the 1" tubular nylon, enough to make the 2 harness for dual deploy. I have enough to have a 3' Y harness out of 5/8" tubular kevlar then 27' of 1" tubular nylon and another couple feet of tubular kevlar to attach to the ebay. All in all about 33' total and the main will attach at the upper nylon to kevlar connection 3' down from the ebay.


The package fits nicely in the booster and slides in and out no problem. I will select a pilot chute and use a large nomex square to protect that from the seperation charge.

I have about 7.6" diameter by 22" (997ci) and 3.9" by 20" (238ci) for a total volume of 1235ci to pressurize and separate the airframe at apogee. The main in the deployment bag takes up a lot of the space, and I will not use any shear pins just friction fit for the booster to ebay for the single deploy flights.

I want to get the recovery harness together enough to test that later this weekend. Our next local launch is planned for July 11th, I plan to be there with my Wife and Daughter for their first high power launch. I have other rockets I will be flying but I will bring this project up for people to see, I hope to find someone who has flown a bigger rocket like this one to look at it and give some feedback.

~John

 

[GalantVR41062]

Ground testing the apogee event. I tried 3grams of fffg black powder for the first test and the airframe did not move and I noticed I have a lot of blow by in the ebay to booster connection. It's a snug fit but the weight of the payload is causing a slight sag (1/8" - 3/16") and a air gap on the top of the joint.

I had used a online calculator with the 1200 some cubic inch space I need to pressurize and the 3g should have been 3-4psi, after the first test I felt ok to double the amount. So 6 grams separated the airframe, the deployment bag made it out, but landed on the ground at the base of the cooler, so just enough.


6 gram test.



7.5 grams produced a more energetic event, the booster pushed back on the fence and slide forward 3" vs the 6 gram test of only 1". With the heat of the day the fiberglass resin on the inside of the booster was a little sticky, with the rocket vertical the payload slides in and out of the booster with no problem.

I will be changing the charge wells out to the large copper caps, the big PVC ones are way to big, so that will clean up the ebay ends nicely. And I figure I can pack at least 9 grams in the copper cap, I had room on top with the 7.5 grams. I think primary charge will be 6.5 grams, and the backup 7.5-8 grams.

I feel this was a good worse case scenario for the apogee event. I plan to do another skim coat of resin on the ebay to boost connection. I will then sand and paint for tighter fit. I will also use some graphite or something to aid in the separation of the airframe.



I used my sewing awl for a couple hours this weekend and have the recovery harness made.
After loading the recovery harness prior to the ground test I changed the 3' kevlar to 1" tubular nylon connection.

I do not have it as a Reef knot anymore but am using the 3/8" quick link for: booster harness, 3' kevlar to ebay, deployment bag strap, main chute harness.

I need to pack the main in the deployment bag again and use a fishing scale for the amount of force needed to pull the main out, I am not sure the 24" fruity chute will be enough for actual flights.

I need to put some heat shrink over the loops and stress test the harness for 1500lbs of load, I do not have a way to test it for more then that atm. I feel the harness is sufficient for a nominal flight and will be looked at after/ before each flight for issues.

~John
View attachment 20200705_204300_001.mp4

 

[gna]

1/4 scale on left, 1/24 scale on right:

 

[David Schwantz]

I wanna see it strapped to the top of your car

 

[OverTheTop]

Nice. Looking forward to the flight.

For a display stand try using an office chair base. You can use the existing column or bolt on the motor case.


That's a 98mm case there. Bases without casters are more stable.

 

[GalantVR41062]

I have built a structure to lay the rocket horizontally, I can prep the rocket for flight, do finish up work on the fins, transport both to and from the launch site and out to the pad and back from the LZ, display at the launch etc. The frame has 2 tires that I can take off, then strap the frame to my parents yard trailer, then strap the rocket to the frame for transport.





I will be covering the 1 x 3 boards with thin carpet to protect the rocket. I also need to attach a handle 3 feet long to the front of the frame to pickup and move it around as needed. I plan to also setup pegs on the side to display other rockets at the launch.

I was looking at the fins the other day and noticed one was just a little warped, this piece of plywood has a couple knots on one side and I originally was hesitant in using it for a fin but did anyway. So I setup about 30lbs of weight on the fin for a couple days, then worked at the leading edge with a sanding block, it's looking better. Now onto a layer of fiberglass on the fins, fillets, and fill the spirals and screw holes with bondo.





I talked with Gary at the launch about the project and going over some more details and I feel confident in doing the finish up work to get this project off the ground.

I will be watching the final build weight as the fiberglass will add 3-4lbs on the fins, and I don't know on the bondo or paint yet. My idea of a 75mm AT K1000t flight might be to small, the club has a 14' long 1515 rail pad. If that motor is to small I will just step up to the 75mm AT L1150R or similar motor for the test flight.

I was not surprised but just about everyone thought it should fly on a M motor, and it should be my L3 bird.

I am still learning, I feel this has been a great learning experience and the next step for me towards the L3 project and certification process. I want to fly this on the huge end of my L2 abilities and motors, and I want to fly my MD birds to extreme heights and see what I like more.

Right now my L3 dream is currently torn on the 2 extremes, huge rocket "low and slow", or MD to extreme flight conditions and altitudes I can only scratch the surface of understanding.

Thank you for the input, thoughts and pictures.

~John

 

[David Schwantz]

Hey John, looking good. I have used windex many times to straighten ply. The ammonia in it helps. Glassing does not need to add tons of weight. Your fins are pretty strong as is and I am guessing that the glass is for finish looks. If you use .6oz cloth, it can stay pretty light. The strength comes from weave direction and not having air under the glass cloth. when spreading out the resin, if it is still white looking, you need more resin. If it it glossy, squeegee out a bit more.
I wish I would have thought of your cart to have used. Might just have to borrow it someday

 

[gna]

I talked with Gary at the launch about the project and going over some more details and I feel confident in doing the finish up work to get this project off the ground.

I will be watching the final build weight as the fiberglass will add 3-4lbs on the fins, and I don't know on the bondo or paint yet. My idea of a 75mm AT K1000t flight might be to small, the club has a 14' long 1515 rail pad. If that motor is to small I will just step up to the 75mm AT L1150R or similar motor for the test flight.

I was not surprised but just about everyone thought it should fly on a M motor, and it should be my L3 bird.
...

Right now my L3 dream is currently torn on the 2 extremes, huge rocket "low and slow", or MD to extreme flight conditions and altitudes I can only scratch the surface of understanding.

~John

I'm afraid I was no help--way past my skill level. Was nice to talk to you about the project, though.
I vote for Low and Slow.

 

[Leo]

Was this project ever completed?