Thales Starstreak build

[DrewW]

Alright, I've found lots of posts about people over the years talking about building one of these. I'm here and going to actually do it. If any one else has actually finished, please drop pictures below. For anyone who isn't familiar with the Starstreak it is a pretty amazing defense article. Crew serviced and vehicle launched versions have been created but essentially a surface to air missile which stages and deploys three darts which I believe are unpowered (as in no rocket motor) but rely on drag separation of the booster to initiate free flight (at approximately Mach 3); following separation the darts guide via a beamrider configuration and use a unique spin control schema for stability and control rather than a CAS.



Just to preface, I've not seen one of these in person, so my scale here is probably not spot on but aiming for a full-scale system when I'm done, based off the best info I can find, and some good guess work. If anyone has measurements please let me know where to find them...

Corrections: This is also a man-portable system and can achieve Mach 4 at burnout according to some information I just came across.

 

[BrendanH69]

YES!!! I'd tried to build an Openrocket sim for one about a year ago, but seem to have deleted the file.

You're right; its a hypersonic kinetic impactor. Ship and vehicle mounted variants too. One of my old QUB university buddies was on the development programme at Short Bros, Belfast, before it was Thales.

 

[BrendanH69]

Here's' a few photos I grabbed from the internet for my "mood board" when I was playing around with the concept. I seem to recall that stability was going to be an issue due to the lack of a traditional nose-cone for ballast.

 

[BrendanH69]

Correction...explosive darts.

 

[DrewW]

@BrendanH69 thank you!

Starting with the darts, there are some challenges to building a scale replica. Because the actual darts have a two canards just below the nosecone, the CP is moved well forward in the model as seen below.



According to Wikipedia the darts are 22mm in diameter and 396mm in length. Knowing that I can do some measuring, but first I've pulled together a rough model in open rocket that I'll "tune in". I'm planning this with an 18mm motor mount inside so I can do some initial flight and stability checks of the darts on their own to make sure I understand how to manage stability.



With significant nose weight managed with steel shot and epoxy it looks like I can get 2.59 calibers of static stability. However, I'm going to play some physics tricks here and do something more akin to the actual device. If you notice the central tube in the model, the intention is to use an 8mm OD hollow tube as an axel for rotation of approximately half of the body tube, inclusive of the canards and nosecone. This will allow for some rotating mass and a gyroscopic force which will add to stability with reduced nose weight...how much is the big question. I could do some complicated math or I can build a test model and play around with it. I like the latter choice, to keep it extra safe I'll use my kids' stomp rocket setup for initial stability checks before loading an B6-2 which for the high mass sims out at ~150 ft. I know this is over estimating since significant energy will be lost to rotation.

In the mean time, I don't have all the kit pieces here right now so I've sent in an order for enough body tubes, couplers, and nose cones to make three final darts and another three accounting for catastrophic failures along the way.

 

[BrendanH69]

Rotation/gyro stabilisation - that sounds both interesting and a challenge! by the way - did you chose to go with 3 fins instead of the 4 in the photos for any particular reason other than simpler?
A project like this could be a really good technical challenge for me as well as being interesting.

Some the questions I was posing myself were:

• Scale? - I was thinking of scaling relative to the dart to take 18mm motors too. 18mm motors keep the costs down a bit, and BP motors may be less of a challenge to airstart after enduring 2 previous staging events. The next challenge then becomes getting a source of 130mm/5inch body tube.
• Powered Darts that separate and airstart them as well as the second stage? I quess you've answered that question!
• No of stages? - Booster stage + air-started sustainer second stage + air-started darts? - deployment/separation technique of the darts will be a challenge.
• Boost and sustainer power - I was thinking of using 38mm and/or 24mm CTI G motors (its what I can Buy2Fly).
• What's the difference between the Starstreak and Starstreak II - from the various photos I can see a difference in dart fin shape.

 

[DrewW]

Rotation/gyro stabilisation - that sounds both interesting and a challenge! by the way - did you chose to go with 3 fins instead of the 4 in the photos for any particular reason other than simpler?
A project like this could be a really good technical challenge for me as well as being interesting.

Some the questions I was posing myself were:

• Scale? - I was thinking of scaling relative to the dart to take 18mm motors too. 18mm motors keep the costs down a bit, and BP motors may be less of a challenge to airstart after enduring 2 previous staging events. The next challenge then becomes getting a source of 130mm/5inch body tube.
• Powered Darts that separate and airstart them as well as the second stage? I quess you've answered that question!
• No of stages? - Booster stage + air-started sustainer second stage + air-started darts? - deployment/separation technique of the darts will be a challenge.
• Boost and sustainer power - I was thinking of using 38mm and/or 24mm CTI G motors (its what I can Buy2Fly).
• What's the difference between the Starstreak and Starstreak II - from the various photos I can see a difference in dart fin shape.

@BrendanH69 great questions!

In some dart only images I clearly see 4 fins, but in many of the all up rounds I see 3 rather than 4...observe pixelated close up below, where to my eye, I count 3 fins with a nominal 120° separation.



3 fins also makes it easier to mechanically couple the dart to the central pillar of the booster element which I'm going to use to my advantage later to spin up the dart forward sections while minimizing energy loss to the darts' aft section

Initial play at darts will be 1.09:1 (9% upscale) because BT-50 is convenient for working out the engineering challenges. That would imply a 5.56" or 141mm booster section OD however (although there is a obturator of sorts so the tube is likely 5" OD or thereabouts); I'll have to look and see if that scale is convenient for parts selection when I map it out. If so, I may keep the 9% upscale.

I will make powered darts possible, but that will be the final version of this. In the interim I'm planning to use the boot motor ejection charge plumbed through the body to provide separation force as a faux piston launcher.

First go at the booster will be single stage. Will follow with an additional stage as the project gets close to its final form. This would technically be 3 stage capable in its final form, though it may be confined to single stage with a faux second stage.

Initial sim for the single stage booster element sims as needing no smaller than an H152 but by the time realism sets in I'll probably be looking at average thrust no less than 180N (purely an engineering guess based on my sim->reality execution)

I don't clearly understand the Starstreak vs. Starstreak II differences myself, but I have some means of finding out at least some details. I'll look at that over the next couple weeks.

 

[BrendanH69]

Agree with the BT50 choice. I've started looking at body tube and nose cone suppliers in NZ and USA to see what's cost effective as scratch making them all wouldn't make time/cost sense.

I think you may be right on the step by step approach to staging to see how it performs, although it would be worth having the finalised design in place and built in modular form capable of being disassembled later for upgrading to the final goal of 2/3 stage.

For dart separation out sideways, I was initially thinking that I might have to rig some sort of BP pressurisation in the upper carrier. The piston approach could also work. The challenge is in the timing of the pressurisation to push the darts off AND ignite the dart motors at the right times. Motor ejection timing is too imprecise for this as the specs for this are stated as being +/- 2secs to the figure on the packaging/label.

Just had a thought - could the central dart carrier have 3 mini launch rails in it to hold them in place? Drag separation might be an issue perhaps.

In this close up, I can see (assuming symmetry) 4 fins. The fin shape in this photo is trapezoidal as opposed to the purely triangular fins I've seen in other photos, prompting me to think if this is a difference between the Starstreak and the upgraded Starstreak II. Will have to research that some more.

 

[BrendanH69]

Launch sequence and timings. I wonder, do the darts ("Hitiles" apparently) separate only under the spin of the sustainer ("Bus") in this video.

 

[neil_w]

Very interesting subject! Looking forward to see how this one goes.

 

[H. Craig Miller]

I created a RockSim design of the Starstreak some years back; I'll look to see if I can find it. More recently, a bought three of the Honest John Rockets from Walmart and was thinking about doing a bash of the Starstreak with an Honest John looking theme.

 

[DrewW]

Agree with the BT50 choice. I've started looking at body tube and nose cone suppliers in NZ and USA to see what's cost effective as scratch making them all wouldn't make time/cost sense.

I think you may be right on the step by step approach to staging to see how it performs, although it would be worth having the finalised design in place and built in modular form capable of being disassembled later for upgrading to the final goal of 2/3 stage.

For dart separation out sideways, I was initially thinking that I might have to rig some sort of BP pressurisation in the upper carrier. The piston approach could also work. The challenge is in the timing of the pressurisation to push the darts off AND ignite the dart motors at the right times. Motor ejection timing is too imprecise for this as the specs for this are stated as being +/- 2secs to the figure on the packaging/label.

Just had a thought - could the central dart carrier have 3 mini launch rails in it to hold them in place? Drag separation might be an issue perhaps.

In this close up, I can see (assuming symmetry) 4 fins. The fin shape in this photo is trapezoidal as opposed to the purely triangular fins I've seen in other photos, prompting me to think if this is a difference between the Starstreak and the upgraded Starstreak II. Will have to research that some more.




View attachment 439234

@BrendanH69 This is great, and thanks for the video! Clearly you are correct about the four fins, and I'll have to make the change in my OR model. Good news is that clearly has a positive impact on the static stability of the darts, which means I can consider shaving down the nose weight which is currently a somewhat ridiculous (in my opinion) 40g for a rocket of this size.

You are right on with the mini launch rails on the central carrier, that was how I envisioned it as well. Thankfully because the bus (as you put it) is already moving at high speeds this can be very very short. I'm thinking on the order of 2-4" just enough to guide to a clean separation.

To your point on the ejection charge timing, I could use a timer for a BP initiation generating enough gas to drive separation, maybe something like this spider design. Alternatively, using motor ejection, if the coast time is going to be sufficiently long I just need to pick a motor ejection time that has enough margin to support a charge 2 seconds later than planned. After apogee would be unfortunate and would seem unsafe.

The darts themselves need an ejection charge to have a chance at recovery. I'm thinking about using some Eggtimer Rocketry Apogee altimeter/deployment charge controllers. They just fit a BT-50 and I happen to have two in my pile waiting for a project.

I’ll post my OR model roughing in the bus a little later when I’m back on my desktop, but I’m thinking that the central carrier will also be where I stow any air start equipment, in fact this may be an opportunity to design in a modular avionics bay capable of suiting any of the configurations and maybe a drouge chute while I’m at it.

 

[DrewW]

Here is a first cut at the bus section flying a single 38mm motor though I may grab a Public Missiles 54mm motor tube because I have the adapter setup to pull it down to a 38 or 29, adding more flexibility while working out the engineering challenges. Ultimately though I want to fly this pretty low so the darts don't disappear. So lets call that nominal bus apogee 1000-2000ft AGL. First pass at mass definitely puts this in the HPR category (>1500g) when flying with the darts/mass simulants. Most H & I motors in the range of 150N - 400N of average thrust seem in keeping with altitude desires while providing enough speed off the rail for stability. Judging from these initial conceptual results, I don't think I'll be a huge fan of taking this all the way to a boosted bus. Though figuring out the fin deployment and fin lock mechanism seem like they'd be a fun challenge.

 

[Ez2cDave]

 

[teepot]

Will you tube launch or rail?

 

[DrewW]

Will you tube launch or rail?

First versions will definitely be rail launched. Tube will have to be down the road a ways, plenty of other engineering challenges just in the darts and bus to get started.

Order of challenges
1. Gyroscopically stabilization of darts off a rod
2. Single stage bus w/o darts
3. Single stage bus with non-separating darts
4. Single dart deployment coupled to an ejection charge
5. Dart air start
6. Full three dart, air start config

Then depending on how I’m feeling about the challenges of the project...
7. Fin deployment/fin lock for boosted bus
8. Boosted bus, captive darts
9. Full three stage configuration
10. Tube launched 2/3 stage configuration

And if anyone asks if I’m planning to vehicle mount in addition to all that I will let out an exasperated sigh and say no, no I will not. Unless someone is planning on providing sponsorship.

 

[BrendanH69]

Started designing the darts and the bus/carrier in Openrocket.one Heavier then I'd initially thought, but can tweak it as concepts develop. Initial design is a keep it simple/traditional with fixed TTW fins and a removable AV Bay/coupler under the transition to do the complicated bits for air starts for the bus stage and the darts.
Still a little unsure of the proportions, from a visual point of view.

 

[BrendanH69]

Sorry...updated sim...

 

[DrewW]

Yesterday I had three packages arrive with all the tooling and supplies I need to work out the darts’ design. I had told my kids a few days ago we’d do some flying at the local school field this weekend, so hopefully I’ll be able to rough in a dart build this Thanksgiving (US) to have a first design ready to fly.

 

[DrewW]

Alright, no glue here and somewhat the "exploded view" but I put together a first mockup with a clear BT50 section at the forward end to see how things should be placed internally for adequate spacing before I start cutting or permanently attaching. Then I decided if something was going to fail it would be in the forward section anyway, so my first version will actually look remarkably similar when assembled.



Two part nosecone may perhaps need some ballast when all done, perhaps not. 12" chute packaged with wadding. I used orange tape to make the two bearings more visible. These will nominally have significantly less tape at assembly and be rigidly mounted inside the red coupler seen just aft. A hollow aluminum rod runs through both creating an axel and also a blow through path. Then will have an appropriate length of BT50 to make up the scaled length. Also, I still need to figure out routing for a kevlar shock cord...maybe I'll anchor it to the axel loosely, notch the tape and route it through? Below you can see the aft section



BT50 tube, with the aluminum rod running axially. I have an 18mm motor mount with two centering rings, but I need to make sure the ejection charge vents where I want it to so I will use the punch out of the 18mm centering ring drilled for the rod to act as a cap and a centering ring itself.

Since this was the first look at how it would go together I haven't finalized lengths yet, but plan on cutting paper and aluminum tubing tomorrow. Then prepping, gluing, and final assembly. Fins will be cut from 1/8" balsa for this pass, but I need to work on shaping/canting for appropriate rotation rates. video of initial spin test below.

View attachment IMG_9052.mov

















Not great spinning. Needs more mass further out (radially) to maintain the rotation better, however, I'll be able to check in front of a fan when I get some canards on. I think I'll start with a 10º cant and see how well it works in a flow field.

 

[BrendanH69]

Which nose cone for the Dart did you go for?

 

[DrewW]

Which nose cone for the Dart did you go for?

Apogee components PNC-24D
I don’t think it’s the perfect shape, but it’s pretty close.

 

[BrendanH69]

Hi Drew. I had the PNC-24D on my shopping list along with the PNC-24A from Apogee. Ended up ordering a bunch of Estes PNC-50s and other supplies from Aerospace Education in New Zealand. Will take a couple of weeks to get here. Shipping was much less than a USA order.
Initial build plan for the Darts is:

• Make up several sheets of fibreglass laminated 3mm plywood for raw material for the fins and canards. Food-saver method is looking on the cards, just need to get one!
• Lightly fibreglass roll the BT50 tubes when they get here.
• Make and fit the canards and then tip2tip FG them onto the body.
• Explore a local cheap source of 5inch tube for the main body parts - trip to the junk shop/recycling centre is on the cards this weekend.

 

[Ez2cDave]

Explore a local cheap source of 5inch tube for the main body parts - trip to the junk shop/recycling centre is on the cards this weekend.

Cheap source . . . Mailing tubes !

Dave F.

 

[DrewW]

Cheap source . . . Mailing tubes !

Dave F.

Good idea. Since this thing isn’t all that sensitive to mass of the booster a glassed (maybe even unglassed) mailing tube is probably a pretty cheap way to get it done especially for prototypes working out the details

 

[BrendanH69]

Have searched all web-sites of local providers of poster/mail tubes - I can't easily get 125mm (5inch) ID tubes easily, unless I fly to Melbourne and pick them up!
Visited the local re-purposing / recycling centre and had a few good scores today. In the photo below are:
Back Row L to R :

• 90mm ID mailing tube sufficiently long for this project, but would bring the scale down to about 70% and the Darts at 24mm might look odd.
• 100mm ID mailing tube (not long enough) with a large sized cotton sewing bobbin thingumy on top that could serve well as part of the bus transition and spine of the dart carrier.
• 125mm (5inch) mailing tube (not long enough) but good indication of scale and I can always use it to make couplers.
• Two 64mm OD mailing tubes.

Front row L to R:

• Some 18mm B6-4 motors for trial sizes in the Dart build.
• Large size cotton sewing bobbin thingumy. OD of the spine is 32mm, base diameter is 113mm, transition length is 45mm.
• 30mm OD tube for scale/reference.
• Medium sized cotton sewing bobbin thingumy. OD of the spine is 30mm, base diameter is 98mm, transition length is 35mm.

Also got 0.2x6m of silver foil plastic/mylar, some material for breather blankets when F/Glassing, and two tube end supports for 77mm (3inch) plastic tubes which can be stands/fin marking guides. Total cost A$15 (excl. the BP motors which were A$26).

 

[DrewW]

Have searched all web-sites of local providers of poster/mail tubes - I can't easily get 125mm (5inch) ID tubes easily, unless I fly to Melbourne and pick them up!
Visited the local re-purposing / recycling centre and had a few good scores today. In the photo below are:
Back Row L to R :

• 90mm ID mailing tube sufficiently long for this project, but would bring the scale down to about 70% and the Darts at 24mm might look odd.
• 100mm ID mailing tube (not long enough) with a large sized cotton sewing bobbin thingumy on top that could serve well as part of the bus transition and spine of the dart carrier.
• 125mm (5inch) mailing tube (not long enough) but good indication of scale and I can always use it to make couplers.
• Two 64mm OD mailing tubes.

Front row L to R:

• Some 18mm B6-4 motors for trial sizes in the Dart build.
• Large size cotton sewing bobbin thingumy. OD of the spine is 32mm, base diameter is 113mm, transition length is 45mm.
• 30mm OD tube for scale/reference.
• Medium sized cotton sewing bobbin thingumy. OD of the spine is 30mm, base diameter is 98mm, transition length is 35mm.

Also got 0.2x6m of silver foil plastic/mylar, some material for breather blankets when F/Glassing, and two tube end supports for 77mm (3inch) plastic tubes which can be stands/fin marking guides. Total cost A$15 (excl. the BP motors which were A$26).

Those are some great finds for prototyping! I especially like the large bobbins. I know your model showed a hemispherical cap to the bus section but my rough model would love those conical bobbins with the cylindrical tops. Looks like I'll need to go to some of the equivalent shops in my locale and see if I can get lucky with some finds.

Scale aside, I figure I'm going to destroy at least 1 or 2 darts working on the spinning mass bit, and also at least one bus working out all the interesting bits there. I'm not to worried about scale while getting the insides to work correctly. I'll plan on going to matching scale for darts & bus when I get all the bugs worked out.

I did accomplish one thing today, I got a new order in with Eggtimer Rocketry and have enough controllers coming in now to outfit my darts (+1) and a couple of cards for DD and airstart control via the bus. Looking forward to getting those in.

 

[teepot]

Those bobbins would make great nose ones. I've used funnels for nose cones, but those look better. Here is an example. Saggar ATGM. Its the right length. But a 4" body tube instead of 5". The bobbin would make a better stand off than the funnel.

 

[BrendanH69]

Here is an example. Saggar ATGM. Its the right length. But a 4" body tube instead of 5".

Love the old school look that funnel gives it!

 

[BrendanH69]

Those are some great finds for prototyping! I especially like the large bobbins. I know your model showed a hemispherical cap to the bus section but my rough model would love those conical bobbins with the cylindrical tops. Looks like I'll need to go to some of the equivalent shops in my locale and see if I can get lucky with some finds.

There were two large bins full of those bobbins; maybe as many as 100! Might have to go back for some more.

I'm totally ignoring the electronics side of things at the moment until I think the design through. It's not something I'm good at, but by QRS club buddy is, however he's mega busy at the moment work wise and so our home-designed flight electronics are not quite done yet - 4 units built to order and received from China, coding and user interface in development. Aim is for a unit price of US$25.

100mm mailing tubes might be easier to get for me, and so I'll mull over using that and scaling down to about 78%, but leave the darts at BT50 / 25mm body diameter if it looks OK after building the first one.