Skylark sounding rocket

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wrad

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Hi everyone

Thought I would start a thread for my latest build project.

I have been looking for my next build for a while since finishing my Soyuz build last year, and wanted to do another scale project. As a Brit if finally settled upon building a skylark sounding rocket.
cleaned up rocket image(25%&comp&crop).jpg

For a bit of background and history, the Skylark program started with the first launch in 1957 and concluded in 2005 with the 441 st launch, making it one of the longest running and most successful launch programs of ever. A complete history of the Skylark can be found in Robin Brands amazing book, Britain's first space rocket, a 700 page encyclopedia of all things skylark and much more, covering a complete history of Britain's rocketry and every single skylark launch and their science missions. The level of details is quite simply staggering, the book is highly recommended reading for anyone interested.
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I am aiming to build fairly accurate model using bt-55 tubes and 24mm motors, I plan on building 2 separate configurations. The first consisting of a Skylark sustainer and a Cuckoo booster as seen in the earlier launches from the 1960's. The model will launch using estes bp motors and will have open air motor to motor gap staging.

cuckoo_2018-Mar-30_04-02-53PM-000_CustomizedView4245170885.pngScreen Shot 2018-04-03 at 14.32.48.jpg
Cuckoo booster.

The second configuration will have the same sustainer as the first, however will have a Goldfinch booster as seen from launches from the end of the 1960s. The larger booster will enable the use of CTI 3 grain 24mm motors in the booster (and potentially the sustainer) pushing the maximum altitude upwards of of 3000 ft. The sustainer will need electronic staging (maybe a seperation charge), dual deployment, and probably some form of tracking. all within the 33mm body tube. its gonna be tight.

Goldfinch_2018-Mar-30_03-51-59PM-000_CustomizedView26123976832.jpgScreen Shot 2018-04-03 at 14.33.09.jpg
Goldfinch booster.

As with all my builds I will use a bunch of 3D printing, and there will be plenty of photos a details to come.

Also I have been trying to improve my 3D modeling so lots of models as above and below to come.

full_skylark_v2_2018-Mar-30_03-22-37PM-000_CustomizedView56799591909.jpg


 
I’ve got an Eggfinder and a Quantum back to back in an Estes 5560 transition. The electronics fit in the 55 side handily. The batteries are fatter and are in the 60 end. I think you’ll have to use more length to fit it all in BT55. It’s a challenge.


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Excellent idea for a build, beautiful renderings. Good luck I'll be following closely!

Robin Brand's superb book is a gift that just keeps on giving...
 
I was at Esrange, Sweden in May 2006 and missed the final Skylark launch by a year. But, I saw the VSB-30 Brazilian sounding rocket that replaced the Skylark. I walked around the launch complex and storage area to see the aftermath. The sides of the launch building have exhaust relief panels that were sufficient for the Skylark booster but not the VSB-30. Sheet metal and insulation were scattered around the woods for a kilometer.

Here's a picture I took of the enclosed launch tower building at Esrange. Build a model of that for a super-scale launch. ;-)

I took a bunch of pictures of an unflown Skylark fin can that was sitting in the storage area. Thought about sneaking it into one of the sea containers we were shipping back to Houston. I wish I could find where I backed up all the pictures I took. Some survive in my blog from that time. There were also many flown rockets piled up in the "grave yard".
 
The fin can would have made one hell of a trophy, or anything from the rocket graveyard!

Currently I am planning to tower launch the rocket, however I will probably just go for a basic tower rather than a scale one just for ease of transport etc.

Build wise things have been slow for a while as my 3D printer and computer both broke at about the same time and i needed both to get on with the project, they are both now fixed so should be getting on with it.

In the mean time I have started collecting the parts and other things i will need, I have got a cesaroni 3 grain 24mm case along with 4 75F51 classics (these were all that were available to me in the UK for now other than a Vmax, although i am hoping to get some other propellants if stock comes in) I already have access to a 1 grain 24mm case as well if i decide to use that.
On the electronics side I have an eggtimer quark and a stratologger CF already, and am looking to add a eggtimer Quantum and eggfinder mini to the collection, with the current plant to fly the 2 eggtimers and the eggfinder. to go with them I have also got some 300mah 2s lipo's for power which are very small yet should have ample power for each of the computers.

Finally a few more renderings this time of the skylarks motor mount

motor_mount_settup_2018-May-05_08-55-45AM-000_CustomizedView827691982.jpgmotor_mount_settup_2018-May-05_09-09-22AM-000_CustomizedView15389173437.jpg
I am planning to use plywood fins mounted through the walls, which may be a bit overkill, a motor hook bent back so as to not provide an engine block. there will be 2 wiring conduits for the igniters and separation charge wiring. finally there is little space for a coupler to fit between the booster and sustainer, so i plan to use a very short coupler at the top of the booster along with 3 guide rods which will insert into the corresponding guide rod conduits in the sustainer these will correspond with the interstage section from the cuckoo booster.
 
Cool project

On your BP motor version, will there be a modification for the booster to deploy a streamer or some other recovery device?

At least as pictured, in post 1, I don’t think the booster will tumble. I think it may remain stable and come in ballistic.

Tom
 
currently there is no provision for a recovery device as its narrow diameter and using gap staging, however i have been considering using some forward plexy fins on the booster to help with tumbling. To be honest however that version of the rocket is a secondary goal for me that i was mostly wanted to make for show purposes as the main goal is to attempt electronic staging.
 
Its taken me far longer than planned to get started on this build, but i finally got all the bits together i needed to get going and the rockets nearly done now so lots of build pics to follow.

The main motor mount first with, 3 conduits for the stage couplers, 2 for staging wires, motor hook, recovery harness and 3 3D printed centering rings all of which slotted together nicely to make a crazyly over complicated motor mount.
IMG_5827.JPG IMG_5829.JPG IMG_5866.JPG
The fins are made from 3mm ply with hand sanded bevels.
The body tube was slotted for the fins and motor mount glued in with epoxy, followed by the fins with the help of a jig and finaly epoxy fillets.
.IMG_5869.JPG
 
The 2 boosters were put together very simply, i didnt get many pictures of them as i went but the are very basicly constructed with just motor mount and 3d printed centering rings, the interesting parts being the fins and inter-stage couplers which were again printed, and the retainer for the larger booster which was also printed, the boosters were then finished with carbon rods to couple with the motor mount of main stage of the rocket.
IMG_5838.JPG IMG_5851.JPG IMG_5854.JPG IMG_5872.JPG
 
For the nose cone, you guessed it, i used 3d printing to make a cone with a compartment large enough for an eggfinder mini and battery, leaving just the av bay to go, by far the hardest part of the project.
IMG_5839.JPG
 
1 eggfinder quantum, 1 eggfinder quark, 2 300 mah lipos, and 2 micro switches setup for pull pins all to go in a av bay 29 mm id by 150 mm.
IMG_5949.JPG
This rely was not easy, it took about 3 weeks and 5 or 6 versions however it works, the 2 flight computers are held in channels one on top of the other, with the 2 battery's at the other end, the switches go in the middle and clip perfectly into a double pull pin arrangement which is part of the outside of the coupler, with an off center threaded rod locking the switches in place and holding the end caps on.
IMG_5883.JPGIMG_5970.JPGIMG_5904.JPGIMG_5943.JPG

For the end caps i am using rubber well nuts for the ejection charge cable pass throughs and for the staging igniter i am using a mini audio jack which will serve as the disconnect at parachute deployment.

IMG_5937.JPG IMG_5938.JPG
 
From hear there was a good few hours of sanding/ filling then priming ready for paint.
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and finally the good stuff
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and how could i forget 77 tiny decals
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only 3 jobs remain now, update the sims with the accurate weights, test ejection charges, and paint the nosecone.

the nosecone hasn't been painted yet as its supposed to look like stainless steel, however it gonna have gps radio tracking in it so i want to avoid metallics and i havent made my mind up/ dont know what to use instead? any ideas welcome?
 
only 3 jobs remain now, update the sims with the accurate weights, test ejection charges, and paint the nosecone.

the nosecone hasn't been painted yet as its supposed to look like stainless steel, however it gonna have gps radio tracking in it so i want to avoid metallics and i havent made my mind up/ dont know what to use instead? any ideas welcome?
Although most Skylark NCs do appear to have been polished bare metal, there's an image in Robin Brand's book (fig 10.16, p304) showing the S11/2 NC as black like the payload section, so you could paint it black rather than metallic. Photos of S26/1 also show a black NC but with a all bare metal payload (p.315), whilst S41 appears to have had a white NC (fig 10.66, p.339)
 
So I went quiet on this thread but finally have something to post.

I flew the skylark last September, It didn't go as planned, launching on a CTI F51 to E22. I know now probably not the best choice for a first flight. I dont think there were any pics or video, however the rocket flew unstably with the general conclusion being it needed a better stability margin and more fin area, with the motor situated far behind the fins, the fins just couldn't keep the rocket straight. Anyway, the altitude lockout on the quantum worked great, so the second stage didn't fire and the rocket recovered well with no damage.

So I scrapped the booster and built a new one with clear fins this time, fixing both my problems of stability margin and the fins being relatively far from the motor.

On Saturday and Sunday the Skylark flew again. On Saturday I flew the rocket as a single stage, with a CTI F51 again. She flew great to 2288 ft and recovered well all be it a long way from the pad (drogue was a little big and not needed) however I got to test the tracking for the first time which worked great with an eggfinder mini.
IMG_8076 crop.jpg IMG_8080 crop.jpg

On Sunday we flew again as a 2 stage CTI F51, to estes D12. The boost was great however the second stage failed to light.v recovery deployment was perfect however with both the booster and sustainer recovering from 1352 ft.
IMG_8402 crop.jpg IMG_8404 crop.jpg

After recovery and analysis of the rocket and computers, we found the second stage igniter handed fired, It did however work when tested subsequently, the quantum showed no firing of the igniter channel for second stage ignition (just the drogue) and showed that the altitude lockouts had bean achieved so it should have fired. This leaves the conclusion that the headphone jack connector used for connecting the second stage igniter to the electronics bay had come disconnected at launch, resulting in a loss of continuity and no ignition. A very easy fix.
Skylark 15-9-19.jpg

So I will try again soon with a stronger connector for the second stage igniter.
 
So I went quiet on this thread but finally have something to post.

I flew the skylark last September, It didn't go as planned, launching on a CTI F51 to E22. I know now probably not the best choice for a first flight. I dont think there were any pics or video, however the rocket flew unstably with the general conclusion being it needed a better stability margin and more fin area, with the motor situated far behind the fins, the fins just couldn't keep the rocket straight. Anyway, the altitude lockout on the quantum worked great, so the second stage didn't fire and the rocket recovered well with no damage.

So I scrapped the booster and built a new one with clear fins this time, fixing both my problems of stability margin and the fins being relatively far from the motor.

On Saturday and Sunday the Skylark flew again. On Saturday I flew the rocket as a single stage, with a CTI F51 again. She flew great to 2288 ft and recovered well all be it a long way from the pad (drogue was a little big and not needed) however I got to test the tracking for the first time which worked great with an eggfinder mini.
View attachment 393621 View attachment 393622

On Sunday we flew again as a 2 stage CTI F51, to estes D12. The boost was great however the second stage failed to light.v recovery deployment was perfect however with both the booster and sustainer recovering from 1352 ft.
View attachment 393623 View attachment 393624

After recovery and analysis of the rocket and computers, we found the second stage igniter handed fired, It did however work when tested subsequently, the quantum showed no firing of the igniter channel for second stage ignition (just the drogue) and showed that the altitude lockouts had bean achieved so it should have fired. This leaves the conclusion that the headphone jack connector used for connecting the second stage igniter to the electronics bay had come disconnected at launch, resulting in a loss of continuity and no ignition. A very easy fix.
View attachment 393625

So I will try again soon with a stronger connector for the second stage igniter.
Thanks for the detailed write up and sorry to have missed this - as you know I couldn't make Midland Sky this year. Good to see progress on this very interesting project.
[Edited to remove irrelevant content - I should have re-read the thread...doh!]
 
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Thanks for the detailed write up and sorry to have missed this - as you know I couldn't make Midland Sky this year. Good to see progress on this very interesting project.
[Edited to remove irrelevant content - I should have re-read the thread...doh!]

Thanks you missed a great weekend, not to rub it in. Im rely happy with the flights even without the second stage firing I learned a lot about the rocket and electronic staging, i'm especially keen now to get a perfect flight with this rocket and try other electronic staging like your air start cluster. I think the last flight photo with the clear fins hardly visible is great and looks very authentic to the real rocket, Its hard to tell its such a small model.
 
What are those fluffy things around the rail? Look like mic windsocks

They are microphones, we had a sound effects recording studio come to record the sounds of rocket launches at our club.
 
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