Thales Starstreak build

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BrendanH69

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Not much progress in the last week due to recovering from the cold and work catch-up. Too windy yesterday to do any painting, but today was better.

  1. Modified the stand to hold the upper assembly of the Darts + Dart Carrier + Fwd Transition + AV Bay while I prep it or work on it.
  2. Masked and then sprayed some chrome-like paint onto the top end of the tube launch motor.
  3. Gave each of the three Darts 2 light coats and then a heavier final coat of the Spaz-Stix Mirror Chrome spray paint I'd purchased.

The quest for chrome shine finish wasn't worth the expense in the end as the results were lacklustre as... well...they lacked lustre! The finishes in the photos below are:
  • The Dart Carrier and Fwd Transition have 3 coats of A$25 "White Knight Super Chrome" chrome-like paint + a gloss clear coat, which actually seemed to dull the shiny aluminium-like finish.
  • The 3 Darts have Spaz-Stix Ultimate Mirror Chrome spray paint on their exterior surfaces. Definitively a brighter, shinier silver, but defo not mirror chrome. Required 2 spray cans for all three Darts (3.5oz/99gm paint in each), total A$62 incl shipping.
  • The top of the tube launch motor have 1 good coat of the the same "White Knight Super Chrome" chrome-like paint as the carrier and transition BUT NO gloss clear coat (yet).


Shiny Darts pic1.jpg



Shiny Darts pic2.jpg
 

DrewW

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Bummed, launch was scheduled for this week but persistent daily high temps above 110F (43 C) during the day have held off launches. We talked about starting earlier but temps were over 100 F (34 C) by 9am. In fact, the other night it was still 100 F right about midnight. My spinning dart was slated for multiple launches, I don’t see much relief coming in the next few months 😔
 

BrendanH69

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persistent daily high temps above 110F (43 C) during the day have held off launches. We talked about starting earlier but temps were over 100 F (34 C) by 9am. In fact, the other night it was still 100 F right about midnight.
Damn...more waiting!
Have holiday'd in Phoenix a few times over the years as it was relatively easy for British Airways employees to get staff seats there and back rather than Vegas. One of my favourite parts of the world. However, the 40 C and over in summer isn't fun for doing a lot even when its a dry heat! Local summer "monsoons" were also an eye opener for sure, and are fairly similar to our local summer storms here in Brisbane.

Desert botanical Panorama 3.JPG
 

BrendanH69

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Found an .svg file for the Thales logo which is crisp, nice and high resolution for giving the Bus it's logos in the final paint scheme. Added my own Starstreak bit (I chose Arial Narrow 54 as my font) then printed it on A4 as a trial for sizing.

Trial logo.jpg



Being an .svg file I believe that I can easily upload it to my (yet to be set-up) Cricut Explore Air 2 and cut it out as a stick on decal on some nice holographic vinyl I bought. Or I could just inkjet print this onto some waterslide transfer paper and stick it on that way, but I do find that that method tends to be a bit low resolution and often has ink run/wrinkles for larger scale decals.

Choices...choices????

https://commons.wikimedia.org/wiki/File:Thales_Logo.svg
 

BrendanH69

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After all the rain stopping progress yesterday, I took the opportunity to carry out the first deployment ground test of the Thales Starstreak today.

As per standard CTI Pro38 motor deployment charges, I used 1.3g of 4F BP and the glove tip method in my Pro38 "Test Motor" using an old Estes electron controller to ignite the e-match. The test motor is just an old cardboard packing tube from a Pro24 6G motor with a used Pro38 charge well wedged in the top end and a stepped centering ring at the back to fit inside the 38mm MMT screw retainer.

Clean enough deployment pulling a 330g dummy chute out of the body and about 2/3 of the shock chord with it.

Nest ground test will be once I modify it for one or two shear pins.



















IMG_2073.jpg
 

BrendanH69

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Built a Dart test rig out of spare parts, with the intent of trying out the Kevlar thread burn-through restraint idea as a safety feature in this project.

Initial thought is to tie a slip knot and secure a loop of Kevlar chord under the motor screw retainer, run it back through the ignitor hole where it will be tightened under a screw head on the base plate under the carrier (spool) or the plywood ribs inside the fwd transition.

If the thread burns through, the test dart will "launch" up the rail but be restrained by the upper stops bolt. Will give the base a spray of paint and then put some markings on the test Dart and the rig to give some measurements.

Need to confirm:
  • If BP motors will burn through Kevlar thread/chord.
  • What gauges of Kevlar thread under tension will a B6 or C6 black powder motor burn through.
  • How much will the angle of the thread & distance from the nozzle be an issue.
  • How quickly the burn through will take.
  • Whether there is sufficient thrust after burn through is achieved for the Dart to still launch away from the carrier rail.
  • How much damage will the carrier transition sustain.
Restraint test rig build pic4.jpg


Restraint test rig build pic1.jpg


Restraint test rig build pic3.jpg
 

BrendanH69

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Performed the ground “burn-through” test for kevlar safety tether idea for the Darts.

Used a B6-4 motor and 0.03inch (0.7mm) Kevlar shock chord tied around the threaded end of the Estes 18mm motor retainer, then over a little guide made of plywood to position it at a more optimal angle underneath the motor exhaust.

Appears it will work well. The kevlar burned through really quickly without much hesitation. So much so, the test Dart sheared off it’s rail guides and went for a little unstable flight. Didn’t go high or far, landed in the grass the other side of the fence and no damage to people or property.

Kevlar Safety Tether Test pic6.jpgKevlar Safety Tether Test pic2.jpgKevlar Safety Tether Test pic3.jpgKevlar Safety Tether Test pic1.jpgKevlar Safety Tether Test pic4.jpg

Video below:

 

BrendanH69

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Another learning point from re-looking at the photos and video - A fair portion of the hot motor exhaust vented through the ignitor hole immediately under the Dart which would mean it will get into the forward transition cavity. So, I'll need to plug those holes with some clay/putty after the ignitor has been passed through it.

1626684705195.png
 

BrendanH69

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Installed rail buttons on the BUS. Located them on the fwd and aft spacer rings. Used similar nut inserts as for the removable fin can and fwd transition builds.

Also, modified the Bus and the fwd end of the AV bay to take a single 2/56 shear pin.
Cut two thin steel sheets from a food can and formed them to the required curvatures, recessed and CA'd them into the cardboard tubes last night. This morning, I then drilled through the assembly, hardened both holes with a drop of CA and finally re-aligned them together again and tapped them. Seems to have worked fine, but currently a bit too windy for a ground test, plus would probably benefit from a bit more drying time.

In the process, I noticed that the embedded nut inside the carrier for the End Cap Nut had fallen out and was rattling around. As this is a major retention method for the Darts when test flying, it's clearly telling me now that it is obviously too weak. Reinforced the design with three very small screws from the side into the internal insert to hold it firmly in place, then epoxied in a nut insert. Should be a more solid fix.


Shear Pin Install pic1.jpgShear Pin Install pic2.jpgCarrier End Nut reinforcement.jpg

While the fwd transition and Dart Carrier assembly is split from the AV Bay, I'll have a look at finalising the Kevlar shock chord safety retainer modifications as they will need some internal work. Not needed for first test flight, but I'm still awaiting news on my BAMA chute order.
 

DrewW

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Somehow in the last two weeks between working just short of 200 hours, I managed to make it out to a club launch for a couple hours and I somehow convinced the RSO to let me fly my first experimental dart.

IMG_0218.JPG


This was the heaviest of three nosecones, to make it safer for non-boosted flight. Beautifully straight flight (on a C5-3) with canards can spinning off the rod, even though the fly-away rail guide hung on for quite a while. Sadly at ejection the ejection charge wasn't able to pop the nosecone. In fact, even though I had motor retention, the motor ejected itself in the process. Rocket came in nose first and broke. There wasn't much salvageable.

Need to figure out how to conduct more of the ejection gasses down the hollow axel faster to get the nosecone off. Then rebuild, and re-fly.

Halted on my booster for a little while until I find the necessary time to push it forward. Good news is after all these hours at work I'll have plenty of hobby money.
 

BrendanH69

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In fact, even though I had motor retention, the motor ejected itself in the process. Rocket came in nose first and broke. There wasn't much salvageable.

Need to figure out how to conduct more of the ejection gasses down the hollow axel faster to get the nosecone off. Then rebuild, and re-fly.
Hi Drew. Sorry to hear about the recovery issue, but encouraging about getting a development flight in, the canards spinning up quickly and the nice straight flight.

In your Dart build, did you go with the 8mm ID tube for the bearing shaft, as per one of your very early posts? Any way you can up the shaft OD/ID size, which of course impacts the bearings too?

What motor retention method did you use? Maybe a stronger one, like a screw retainer, might hold the motor in longer to get the effect of the gases to work their way up the narrow shaft ID, plus go as light as you dare on the nose cone fit.
 

DrewW

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In your Dart build, did you go with the 8mm ID tube for the bearing shaft, as per one of your very early posts? Any way you can up the shaft OD/ID size, which of course impacts the bearings too?

What motor retention method did you use? Maybe a stronger one, like a screw retainer, might hold the motor in longer to get the effect of the gases to work their way up the narrow shaft ID, plus go as light as you dare on the nose cone fit.
I did build with an 8mm ID, and I think you're right, I need a larger shaft to conduct more gas in the same window of time.

Retention method was essentially a standard Estes approach. 18mm motor tube, with retainer clip. The motor tube ripped free from the centering rings. will need to look at options, but there are probably quite a few easy fixes if I get the axel sized correctly.
 

BrendanH69

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I did build with an 8mm ID, and I think you're right, I need a larger shaft to conduct more gas in the same window of time.

Retention method was essentially a standard Estes approach. 18mm motor tube, with retainer clip. The motor tube ripped free from the centering rings. will need to look at options, but there are probably quite a few easy fixes if I get the axel sized correctly.
For a stronger retention, see the photo below from post no.63. It shows that I used a combination of the Estes heavy duty green cardboard rings, through the wall fin construction between the rings, plus the 18mm screw retainers to give me lots of strength back there. It's certainly over strong for my non-spinning design, but with the narrow, hollow axle design it might help resist and contain the deployment charge pressure for longer while it finds its path up the inside of the axle.

Maybe a ground test would help prove the next build will deploy happily.

Dart MMM pic1.jpg
 

BrendanH69

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Carried out some ground testing with a single 2/56 shear pin inserted.

Good news was that the pin sheared on all three tests. However, I’m not happy with the deployments as they were not energetic enough to drag the dummy chute bundle out.

In Test 1, the AV Bay assembly (with its dummy weight) never separated from the main BUS.
In Tests 2 and 3, the AV Bay assembly did depart the main BUS, but not energetically and the chute bundle remained inside the BUS body tube.























































All 3 tests were with a single 2/56 plastic shear pin inserted. It fully sheared each time, no damage to body nor AV bay, so modifications all good.

All tests used 4F BP. Test 1 was with 1.3g, test 2 with 1.5g and test 3 with 1.8g. I used my usual 38mm test motor method using the glove finger method and an ematch.

The ID of the BUS body tube is 5inches (127mm). Available payload space from the AV Bay rear bulkhead aft to the shock chord anchor plate is approx. 10inches in length (250mm).

Dummy chute bundle for testing is approx. 7.5inches (190mm) long and 4inches (100mm) in diameter. It weighed 330g wrapped with the shock chord and a nomex blanket. It was a close fit, maybe too draggy.

A dummy weight was secured into the top of the Av Bay because the Dart Carrier and Fwd Transition assembly was removed. This weighed 850g, same as that assembly incl. the three Darts.

What’s going wrong? I’m thinking some issues are because:
  • The chute bundle is too tight and draggy.
  • The chute/shock chord bundle take up a significant volume of the payload bay. Is it hindering the deployment process?
  • There is too much gas pressure escaping out – in the videos I can see a puff of smoke venting out the back. It’s coming out from the air-start conduit I’ve built in, which has an ID of ¼ inch (7.2mm).
 

BrendanH69

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Been ages since I progressed this build! Been diverted onto doing home renovation stuff.

Got my lovely 5ft AeroSpherical chute from BAMA Recovery Systems in the USofA. Looks great! Unfortunately they were out of stock of chute deployment bags, so I'll have to make do with a nomex blanket. The chute has a reported Cd of 2.0 and OR sims the landing as 3.6m/s (12fps).

Will aim for the first test flight (without Darts) at the mid October QRS launch day. Have got an Aerotech DMS H550-ST motor set aside for this.


BAMA 5ft Chute pic1.jpg BAMA 5ft Chute pic2.jpg BAMA 5ft Chute pic3.jpg
 
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