Thales Starstreak build

[DrewW]

A little off topic but 3D printer showed up a few days ago and still getting it all figured out building the kids toys and helpful little tools, but planning to solve some of my challenges with the printer over the next few weeks.

until then...

 

[Cape Byron]

Fish bones? You're gonna print your own fish bones?

 

[teepot]

What are you going to do with that. A flying fish?

 

[BrendanH69]

A little off topic but 3D printer showed up a few days ago and still getting it all figured out building the kids toys and helpful little tools, but planning to solve some of my challenges with the printer over the next few weeks.

Rocket launched drone fish?

What's on the plan in your Starstreak build for 3D printing?

 

[DrewW]

Fish bones? You're gonna print your own fish bones?

@teepot @BrendanH69

articulated sharks is the favorite of the kids right now. I may even get to print some unicorns.

 

[DrewW]

@BrendanH69 what dremel bit were you using for slot cutting on your body tube? Unless my wife is cool with me buying a router tomorrow I think I’m moving forward on the dremel path, even if it requires some cleanup work.

 

[BrendanH69]

@BrendanH69 what dremel bit were you using for slot cutting on your body tube? Unless my wife is cool with me buying a router tomorrow I think I’m moving forward on the dremel path, even if it requires some cleanup work.

Hi Drew,
I used the Dremel Router Bit no.650 which is an 1/8 inch (3.2mm) bit.

https://us.dremel.com/en_US/products/-/show-product/accessories/dremel-650-straight-router

It was better behaved this time, with less chatter, probably because I made sure it was good and tightly screwed into the router attachment. The fin can was thick cardboard and it did need some clean up, so I used some sanding paper glued to a popsicle stick and a sharp craft knife.

Haven't done too much on my own build in last week. Just:

• Epoxied on a spacer ring to the aft end of the fin can & soaked the cardboard in that area with epoxy to stiffen it.
• Attached the last two sets of canards to the Darts.
• Applied the fillets to the last two Darts, which need sanded down next.

 

[BrendanH69]

@BrendanH69 what dremel bit were you using for slot cutting on your body tube? Unless my wife is cool with me buying a router tomorrow I think I’m moving forward on the dremel path, even if it requires some cleanup work.

If you're slotting small, thin body tubes like BT50, I found that marking them out and then cutting the long edges of the slot with a thin cutting wheel on the Dremel was best. The router would be too rough for it. I used a Metal Thin Cut wheel (EZ409) using the EZ Lock mandrel (EZ402). Holding the Dremel close in against your body to prevent it kicking about while drawing the BT away seemed to give a good degree of control.

 

[DrewW]

While I was waiting to gather in certain pieces of this build I've built 18 other rockets, I need to start getting refocused on this set of challenges, for which there are MANY!

Prototype SN1 of the airstart system is sitting on the workbench right now, hopefully I'll get that tried out today and figure out what I need to do differently for future device.

Also, taking my first pass at the Christmas light method for electronic ejection charges.

3D printer is here and working the way I expect about 50% of the time but having some underextrusion issues that don't support rocketry builds at the moment, and that also has been consuming time. Hoping to create the tower via 3D printing with built in rails.

Have a dart prototype ready for final assembly, and an Estes "Spin Control" rocket to assess spin stability relative to the hitiles, and their canards. Might take on a side project to see how much canard CP I can ignore versus their spin rate for a non-spinning fin can, but that would be an experiment with many, many rockets built...might need to figure out how to build something more modular to support instead.

Working to roll my own tubes at 1:1 scale, working on getting a craft paper core, that I can glass to get to 4.9" OD. I have the first layer set but keep putting off moving it forward with other projects distracting me.

Also have glassed ~3" tubes I fell into, but also some ~4" shipping tubes someone had laying around after a project that they saved for me.

 

[DrewW]

Spider prototype test #1 happened today, and well...I have some challenges to overcome.



So, you may notice in the video that there is no jetting, just exploding; so that was less than desirable. So what I saw as an issue before but remained hopefully optomistic about was the lack of any features which lock the lower section to the upper section. Thereby expanding gasses separate the two, and you get my results. However, the plans are well drawn and do not show any retaining device, however there is more than twice the exit nozzle area in that design. Also, I'm making use of FFFFg rather than pyrodex, I might need slower burning powder (FFg or RS) to slow the pressure rise and reduce peak pressure.

I noted a significant delay in ignition, roughly 1-2 seconds from button press, with a standard Estes controller at 6.5V.

I used 0.5g of black powder, as measured by a leftover AT ejection charge, also apparently way too much...next test at half that, but probably need to figure out a reliable method to prevent separation.

Parts survived, so thats good.

 

[teepot]

I noted a significant delay in ignition, roughly 1-2 seconds from button press

What were you using for an ignitor?

 

[BrendanH69]

Spider prototype test #1 happened today, and well...I have some challenges

Yikes! Did the table escape unscathed?

 

[DrewW]

What were you using for an ignitor?

Standard Estes igniter

 

[DrewW]

Yikes! Did the table escape unscathed?

it did, I had a wood block under the spider thankfully.

 

[teepot]

Try an e-match. I think you would get faster ignition.

 

[Ez2cDave]

Spider prototype test #1 happened today, and well...I have some challenges to overcome.

Like buying a new table, before someone else finds out ?

LOL !

Dave F.

 

[DrewW]

Figured some things out and made some more decisions and progress today.

My dart plan had the darts statically stable (2.88 cal) not accounting for spinning canards. I'm going to build out several swappable "canard can" sections with a final stability between 0.5 and 3.0 cal (on purpose) to understand some things about how the spinning canards will cancel out the effects of canard CP and what rotational velocities are needed.

Also, going to build a makeshift 12" wind tunnel to assess the rotational speed of the canard can in different air flows.

Original plan had been to use an aluminum rod as the bearing axel and ejection charge gas conduit, at least for first attempt I'm going to substitute some BT-2+ from erockets which is the perfect size. Hopefully that isn't the weak point, but I added significant expansion space in the motor mount to allow initial gas pressure to abate. Along with this, I determined I'll need a 15-18" chute which will still be a harder landing than desired, but I can rebuild. Packing a nylon chute in the space I originally had was going to be difficult so I've re-optimized my forward/aft body tube ratio to provide greater space.

Completed motor mount today and realized my design has some tricky assembly steps that I'll need to refine in future builds, but nothing too crazy.

Happy to be making progress on this project again, even if I did put it off while I built more than 20 other rockets.

 

[DrewW]

I finalized dart design details tonight and made some more progress on SN1.



5º cant for canards which should spin up the forward section and provide some stability. Significant added mass required in nosecone to bring static stability to 0.75cal, which is the lowest I'm comfortable with in light winds until I know more about the behavior...I might add more to reduce apogee and further stabilize, though I'm worried the centrally located mass will damp the rotation. Balancing this out will be important if I'm going to spin stabilize future versions. I've even considered putting a couple steel BBs in the canard to increase the torque moment. Hoping to launch next weekend at my next club launch. Going to use a C5-3 motor for the extra initial thrust. Probably a no-go though if winds exceed 2 m/s.

Will use a 0º alternated canard can also and determine how much energy is lost to momentum dumping/canard drag...this may make an interesting R&D project at some point with enough data points.

 

[BrendanH69]

I finalized dart design details tonight and made some more progress on SN1.

Significant added mass required in nosecone to bring static stability to 0.75cal, which is the lowest I'm comfortable with in light winds until I know more about the behavior.

Yep, I had to add 38gm of nose ballast weight (including the epoxy) to the Hittile nose cone to get just over 1 Cal of stability, and that's without any spin stabilisation system putting weight into the back end.

 

[BrendanH69]

With this weekend's QRS launch rained off, I got a little more build time in to make a little progress.

• Finished the top end of the BUS by block sanding the tube end to get a clean & level edge, then epoxied the top wooden spacer ring into place. For rail launch, these will have the rail buttons mounted on them. Eventually, if I ever get to tube launching, the buttons will come off and these will be the "piston/centering rings" in the launch tube.
• Made up the AV Bay from the home made coupler, 6mm ply lids/deck and M6 All-Thread. The upper 78mm above the fixed "mid-deck" in the AV Bay will be the ignition bay where the Spider will be retained. If I don't use the Spider initially, it can be where I mount an ignition harness, initiated from the AV bay cards below.
• Not necessarily Starstreak related, but I bought a new Tractive pet tracker device as my day-to-day cheapie tracker system A$88 for the device + A$120 Cell-phone'/GPS subscription. Its longer but skinnier than the old one, so it fits into my 54mm nose cone AV bay and my 38mm MD rocket! Been using the earlier generation of this device for just over a year, and it's paid for itself a couple of times over. The "dog" doesn't go out much, but when he does, he goes like the clappers...!

Also started organising my design and manufacturing thoughts on building the upper part of the Nose cone and transition to the Hittile (Dart) carrier.

My intention is to use a polystyrene ball to make the basis of the transition shape and F/Glass over it to form it, then build it up from the inside to strengthen it. I think I'll need to add some strengthening ribs in the transition as it will be carrying bending loads as well as compression. I estimate that, fully loaded with three Darts, the upper part of this transition/Dart Carrier will have a weight of about 850gms.

 

[BrendanH69]

I finalized dart design details tonight and made some more progress on SN1.

View attachment 456061

Significant added mass required in nosecone to bring static stability to 0.75cal, which is the lowest I'm comfortable with in light winds...

Hi Drew, although we don't have much in the way of proper dimensions for the Darts, the photos we do have, seem to show a longer root chord and longer tip chord for the fins. In the end, its a bit of a trade off as the greater fin weight will pull the CG aft as much as the larger surface area might move the CP a little further aft too. I've included a screen shot of my OR file for my Dart design.

 

[DrewW]

Hi Drew, although we don't have much in the way of proper dimensions for the Darts, the photos we do have, seem to show a longer root chord and longer tip chord for the fins. In the end, its a bit of a trade off as the greater fin weight will pull the CG aft as much as the larger surface area might move the CP a little further aft too. I've included a screen shot of my OR file for my Dart design.

@BrendanH69 you're totally right on that. I think this might be another case of multiple versions contained in the images we've seen. I think I've counted at least four hittile fin/canard configurations. I like yours better, they'll go a long way to bring my stability numbers up without spin stabilization, will make me feel better about launching in 3-4 m/s winds if need be.

I have the bearing assembly curing up with the motor mount right now, cutting and shaping fins/canards is tomorrow's task so your note is very timely for me. Plan is a 0º symmetric airfoil set, a 5º canted symmetric airfoil set, and a 5º canted asymmetric wedge set to get a better feel for spin dynamics. At the same time, materials for my wind tunnel (about 2000 straws) just showed up. Planning to mount them in a long cardboard box for laminar flow and measure spin rates vs. air speed. Though that project probably wont be done until after my next launch.

 

[BrendanH69]

At the same time, materials for my wind tunnel (about 2000 straws) just showed up. Planning to mount them in a long cardboard box for laminar flow and measure spin rates vs. air speed. Though that project probably wont be done until after my next launch.

Ahhh....the old "bunch'o'straws" airflow smoothing trick! Takes me back to my old Aeronautical Engineering days, and less fondly, to my airline engineering days and the B777-300 RR engine fuel/oil heat exchanger issue (unscheduled disassembly at end of glide slope)!

 

[BrendanH69]

Minor progress in the last week. OR predicts final weight (with booster and 2 CTI Pro38 G motors) to be about 3.8kg.

• Made my AV Bay sled and did final assembly of it.
• Refined my layout and design of the fwd transition to the Dart carrier on OR, plus updated some OR weights post build.
• Made a small but long coupler to go into the aft conical end of the Dart carrier (cotton bobbin thingy). This is intended to provide some additional bending load stiffness and load path at the bottom of the cotton bobbin where it's going to join into the fwd transition.
• Made a "lathe" with a chorded drill to trial turning my polystyrene ball to form the basic shape the Bus fwd transition prior to F/Glassing over it.
• Did a bit more on the booster construction, mainly external raised rings sections for the look of the real thing.

Speaking of the booster, I did some random internet searching tonight and found a link to 2009 posting on a UK veteran's forum about a query from a guy in the US who had pictures of an inert/used booster rocket found in the US during a range clearance exercise . UK vet positively ID'd it as a UK Gridded Brambling booster - the same booster/tube eject stage of the Starstreak.
Note the lanyard for triggering the ignition of the motor on the BUS, plus the booster nozzle arrangement which must also impart the initial spin rate out of the tube. Interesting.

 

[dhbarr]

That nozzle is -fascinating-.

 

[Ez2cDave]

That nozzle is -fascinating-.

It looks like an AEROTECH "Medusa" nozzle . . .

Dave F.

 

[BrendanH69]

Got more build time in over the last couple of days during the Easter holidays.

• Progressed the Dart carrier which I've started off weeks ago using a recycled industrial cotton bobbin/reel at the core of the design.
• Trimmed and chamfered a thick PVC recycled off-cut to fit and epoxy inside the base of the bobbin, and then marked out for 3 outer holes for the ignitors to pass through and 3 inner holes into which I glued M6 threaded inserts for fixing it with M6 bolts to the (as yet to be made) f/glass nose transition.
• Made a removable mini "carrier end nut" by rough turning some thick plywood. Using a plug which I glued into the open end of the bobbin, I'm going to use a long screw to make this mini nose cone removable. When I test fly the rocket with three inert Darts in the future, I'll take this off and add under it a larger diameter disc to cap off the guide rails so I can lock the Darts and their rail buttons into a fixed position to stop them sliding back and forth on deployment and during descent.
• Drilled small holes in the ends of the rail guides I'd made previously from an off-cut of an Ikea curtain track, and temporarily fitted them to the central core of the carrier with really small screws which I'd also ground the head diameters down on to get them into the "T-slots".
• Mocked up the carrier assembly by taping the three darts into place to get an idea of the final assembly of the current design. Bit of a handful without the rail guides (yet to be made; standard rail buttons and guides are too wide and tall). Aft fin clearances are likely to be an issue, so I might have to shim the mini rails out about 3 to 5mm.

Happy Easter everyone!

 

[BrendanH69]

Had my first ever go at using a styrofoam ball (15cm diameter) as a former for fibre glassing over to make the forward transition. Pretty pleased with the process...so far.

Base diameter of the transition needs to be 150mm so I only had reduce the diameter a little bit using a makeshift "lathe" (aka drill mounted on a plank). Cut it to length as it spun using a hacksaw blade.

Cut paper templates for the pieces of F/glass and refined the shape to cope with the multi curved shape - wave shapes seemed to be best, so cut 18 of them to go round the base, each one overlapping the previous one. I used rip stop nylon as my "poor man's reel ply" as I have tons of it and this works well enough for me.
Repeated the process again after 24hrs to build up some outer thickness before I carve out the inside.
I intend to build up the inner F/glass, fix in a top plate to bolt through into the Dart carrier base plate, add in some reinforcing ribs for structural integrity, and then add in a base "centering ring" through which the screws/inserts will go to be able to attach the whole upper assembly to the Spider/AV bay coupler, similar to my removable fin can.

 

[BrendanH69]

Transition build continues. Cleaned it up a bit and then dissolved out the polystyrene foam former with acetone.

Made up an internal fwd bulkhead from 7mm plywood, marked it out and drilled some of the holes. Also made up 4 internal ribs from some 3mm plywood scraps to go between the bulkhead and an aft internal centering ring (yet to be made), the idea being to support and stiffen the transition body for bending loads . Thinking I might want to go with 6 ribs, but will have a re-think tomorrow before I epoxy everything in place.

 

[DrewW]

@BrendanH69 You're doing an amazing job of this, and I will one day catch up to you. In the mean time I'm learning lots from your process!