Level 2 cert thread - scratch built

Are you looking at tomorrow or Sunday to cert? I'll be there tomorrow, and happy to witness if you need one.

Bat-mite said:

Are you looking at tomorrow or Sunday to cert? I'll be there tomorrow, and happy to witness if you need one.

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I will be there tomorrow and will cert then. I am thinking J350 Skidmark.

I will take you up on the offer to witness if Robert or Fred are not around. I wanted to go over the rocket configuration with Robert and Fred because I am going to be using most of the same techniques and recovery configuration on the L3 cert with the Formula 200.

Robert will be for sure, probably Fred, too. But you'll know where to find me if you need me. Good luck!

NateLowrie said:

I will be there tomorrow and will cert then. I am thinking J350 Skidmark...

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No such motor. Maybe you meant J250 Skidmark or J360 Skidmark.

Nathan said:

No such motor. Maybe you meant J250 Skidmark or J360 Skidmark.

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Good catch. I meant the J360.

I hope that AMW has restocked because I bought their last two J360 Skidmarks last month.

Nathan said:

I hope that AMW has restocked because I bought their last two J360 Skidmarks last month.

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I ran the sims on quite a few 54mm AMW 2 and 3 grains so if they aren't available I'll just choose something else. The J449 Blue is a possibility as is the J355 Red and the J380 Smokey. I wish I could throw a K into it but I need to keep it under 4,000.

Shot some videos this morning of the final configuration. It's gonna fly unpainted and then I am taking it to the local auto body shop for final painting. No sense shooting a quick coat before then.

Here are the airframe details. Covers the fin fillets, aeropack retainer, rail guides, and Av-Bay mounting with PEM nuts.


Here's the Av bay configuration and the charge and ARRD setup.

Well, this went without a hitch on Saturday at the MDRA launch. I chose a baby J280 Smokey Sam for the cert. Launch weight was 14.4 lbs. Flight went without a hitch. Flew up to 1,542 ft. as reported by the quark and 1,536 ft. as reported by the Stratologger CF. At apogee, the Stratologger blew the drogue charge and forced the drogue out. The Quark fired the backup charge 1 second later. It fell on the 15in Fruity Chutes drogue to 700ft. where the Stratologger blew the ARRD. The 48" fruity chute main deployed beautifully and fully from the deployment bag in about a second on a 5' (yes 5') kelvar harness. Both sections plopped within 50 yards of the LCO table for a nice easy recovery.

I still need to download the data on the altimeters.

Special Thanks:

• Fruity Chutes for answering all my questions and delivering an awesome product quickly.
• Ted at One Bad Hawk. He got me 2 custom kevlar harnesses on a very short timetable and they were both excellent quality and just what I needed. Great product and great service.

Notes:

• I can lose the noseweight on future flights. I had 12oz extra weight in the nose. and it made everything a bit heavy for the nose recovery on the drogue chute.
• I love the single compartment dual deploy with an ARRD recovery configuration. I think it will be the standard on the larger rockets and high altitude airframes going forward. I love being able to really shorten the main shock cord length and I love that the deployment is about as risk free as you can get (no chance of tangles or the main not inflating). In my mind it's a lot less riskier than a chute release or cable cutter.
• I love the well nuts for igniter wire routing. So much easier than terminal blocks.
• This is the first rocket I've use kevlar harnesses (and sewn harnesses) on. It worked out so well I won't be using nylon anymore. Ted, thanks again!

Congrats!!!!!

Great job Nate

Congratulations Nate, welcome to L2, where you can now plan on spending more on rocket motors than you do on groceries. Can't wait to see the Formula 200!

Only potential problem that I can see with your ARRD recovery setup is that it might not work in rockets where the main chute is a snug fit in the airframe tube because then the drogue might not be able to pull it out.

I have gone the other direction with recovery harnesses; I used to use Kevlar but have now switched back to nylon because it seems to be more durable. After a lot of use the Kevlar gets worn from abrasion. I've had to throw away a couple of lightweight Kevlar harnesses that were starting to look dangerously worn out.

Nathan said:

Congratulations Nate, welcome to L2, where you can now plan on spending more on rocket motors than you do on groceries. Can't wait to see the Formula 200!

Only potential problem that I can see with your ARRD recovery setup is that it might not work in rockets where the main chute is a snug fit in the airframe tube because then the drogue might not be able to pull it out.

I have gone the other direction with recovery harnesses; I used to use Kevlar but have now switched back to nylon because it seems to be more durable. After a lot of use the Kevlar gets worn from abrasion. I've had to throw away a couple of lightweight Kevlar harnesses that were starting to look dangerously worn out.

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Thanks. I can't wait to see what I do with it either. The initial data packet is almost ready on the Forumla 200. I have a friend that runs an auto body shop that is itching to paint it. Since I dislike painting it's a win-win. I figure I'll get this patriot painted too.

Regarding the ARRD, I definitely see what you are saying. It was a concern of mine but the deployment bag prevents the tight pack. The Fruity chutes d-bags are cut smaller than the airframes they are designed for and slip into the airframe nicely. I can even put it in between the ejection charge tubes and have a nice loose-ish fit. I did ground testing with the patriot and plan on doing similar testing on the Formula 200 to make sure the configuration releases properly.

Fred's done more ARRD deployments that anyone I know and having him as a TAP should provide a good double check on the design.

I will keep an eye on the kevlar. I like it because 1) I don't have to worry about protecting it from the black powder charges and 2) it was definitely stronger and lighter than the tubular nylon. Were you using braided kelvar or tubular kevlar? How many flights did you get out of it?

NateLowrie said:

...I will keep an eye on the kevlar. I like it because 1) I don't have to worry about protecting it from the black powder charges and 2) it was definitely stronger and lighter than the tubular nylon. Were you using braided kelvar or tubular kevlar? How many flights did you get out of it?

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Yeah that is the problem with nylon harnesses, they have to be protected from ejection charges. My Kevlar harnesses were Teddy's tubular Kevlar. I don't know how many flights they lasted but it was a lot. I never had one fail. Just watch them for frayed spots. I still buy my harnesses from Teddy but now I buy the nylon ones. The thing like most about the Kevlar harnesses is that they are less bulky and fit easier in smaller rockets. I'll probably buy another Kevlar one for my 2.6" DX3 because I can just barely stuff the 36" chute and a 25 foot nylon harness into the payload section.

An update on this rocket. It got a paint scheme from my cousin. Again, this is totally hand painted. Will be flying at LDRS on a Kosdon By Aerotech K750.

Nathan said:

Yeah that is the problem with nylon harnesses, they have to be protected from ejection charges. My Kevlar harnesses were Teddy's tubular Kevlar. I don't know how many flights they lasted but it was a lot. I never had one fail. Just watch them for frayed spots. I still buy my harnesses from Teddy but now I buy the nylon ones. The thing like most about the Kevlar harnesses is that they are less bulky and fit easier in smaller rockets. I'll probably buy another Kevlar one for my 2.6" DX3 because I can just barely stuff the 36" chute and a 25 foot nylon harness into the payload section.

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Wow,,
I didn't see this whole thread before..
Thank you all so much for all the wonderful compliments and nice things said..
You too Nathan,, you've been a customer of mine for so long,, right,, I can't thank you enough..
But I definitely disagree with the sentiment of lose of confidence in Tubular Kevlar..
I would like very much to see the harness you're referring to that has shown
enough wear that you have lost confidence in it, I only say that because I have a 11/32" Tubular Kevlar harness where it doesn't really belong,
in "SteamPunk" for well over 2 dozen flights now, I say it doesn't belong because the rockets heavier then I would recommend that material for.. Last flight was 38 lbs on the pad..
To the best of my knowledge you have 3 different Kevlar materials from me..
1/2" Flat Kevlar,, 3/16" Tubular Kevlar,, and 7/16" Tubular Kevlar...
The second 2 you haven't had long enough to show much wear at all..
The first material isn't my favorite,, it's all about price point..
Some people want quality,, some want price point..
Who am I to tell one or the other they're wrong..
So I stock, manufacture, and sell both..
The only material you could have seen wear or fray enough for you to loose confidence in it is the 1/2" Flat Kevlar..
Those harnesses were $12 when you bought them in August of 14,, now they're $14..
I only recommend them for mid power rockets,, some light high power..
The loops won't let go ( that I know of ),, but they will wear and fray..
How many flights did you get out of one before you lost confidence in it ???

Teddy