Full Clip - 54mm MD build

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drew
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Full Clip - 54mm MD build

Postby drew » Sun Oct 07, 2018 11:05 pm

So I've had an L935 sitting with Blake since 2016 or so as I wanted to fly it in a MD airframe at Westmar. Since the purchase Head End Deploy has become a bit of a thing in MD circles, as can be seen by the Wildman "Mach 2" kit. After looking at this rocket design and wanting to incorporate a cable cutter to deploy my main I decided to do away with the conventional AV Bay and instead do something more aggressive. I've built a single break Head End Deploy design that also incorporates a 54mm plugged forward closure threaded rod to serve as a motor mount. See below.

Here's a shot of the fully assembled Nose Cone/AV Bay/motor mount.
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Here's a fully disassembled shot.
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AV Bay in "Mach 2" airframe demonstrating how much of the AV Bay/coupling shoulder will be epoxied recessed in the airframe.
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CTI 54mm plugged forward closure seated against the aft bulkhead.
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Avionics - will be flown with a single axis Raven 2 or dual axis Raven 3 and TeleGPS 1.0.
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I've got the airframe rolled and fins aren't that far out. And there's heaps more left to do. But this is a decent start. Below is a Openrocket sim of a slightly longer and lighter vehicle. I've cut down the AV Bay by 15-20mm from the sim and I always build heavier than any of my preliminary sims. Still, looks good to me!

Image
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 26,850ft - L935 - THUNDA 2019
Max V - 3,004 ft/s, ~Mach 2.67 - L935 - THUNDA 2019

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SpaceManMat
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Re: Full Clip - 54mm MD build

Postby SpaceManMat » Mon Oct 08, 2018 6:12 pm

Wow that looks pretty sweet to me :!: Big motor, little room for anything else 8)
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
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drew
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Re: Full Clip - 54mm MD build

Postby drew » Mon Oct 08, 2018 6:21 pm

SpaceManMat wrote:Wow that looks pretty sweet to me:!: Big motor, little room for anything else 8)


Thanks d00d! Should be a fun flight. :D

For the record every flight I'm planning for THUNDA2 will be leveraging this design in some manner. I'm going to fly a M2245 in a 75mm version of what's above and my two stage stack will have a 54mm sustainer quite similar to above. I won't be able to epoxy the coupler in place on that rocket as I'll need to wire up the HEI forward closure to the staging altimeter before flight so instead I'm going to use a "puck" with some nuts and use countersunk screws to hold the AV Bay to the airframe. The coupler will also be longer as hopefully I'll be fitting a GoPro Session 5 in the NC as well.
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 26,850ft - L935 - THUNDA 2019
Max V - 3,004 ft/s, ~Mach 2.67 - L935 - THUNDA 2019

matthew
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Re: Full Clip - 54mm MD build

Postby matthew » Wed Oct 10, 2018 9:02 pm

This is one of those moments where I said to myself "I wish I'd thought of that."

Nice design, drew. I'm looking forward to seeing it in person. :D
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drew
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Re: Full Clip - 54mm MD build

Postby drew » Thu Oct 11, 2018 12:27 pm

Thanks for the kind works Matthew, I do appreciate it. I must admit I've been mulling this design over in my head for months now attempting to eliminate any pitfalls in the design before I attempt to fly it. I think I've considered most issues but I'm more than willing to listen to any comments about "blind spots" I've not considered.

First off, I have had some concerns about the rocket still being stable post apogee event as I'll only be popping the NC off and leaving the AV bay (and all that mass) in the airframe. I'm not confident the drag of the open ended NC will be enough to stop the rest of the airframe from staying stable, especially considering the fact that there's a sealed bulkhead at the front of the rocket instead of a draggy open airframe. Hence the inclusion of a drogue which historically I've not used in MD designs as I've always been a drogueless sort of guy.

But flying a drogue when I'll most likely be having apogee deployment near or in the jet stream concerns me from a drogue chute shred perspective. So to mitigate this I'll using X-type chutes for the drogue. Top Flight makes X-types at a reasonable price so I'll be ordering a handful of them. Ideally I'd like a 10" reinforced drogue but Top Flight only makes their reinforced drogues in 18" or greater. I suspect I'll "test" the 10" standard x-type on the back of my car somewhere remote to see if it shreds in 100kmh speeds as well as test fit the 18" in the 54mm nose cone. I might move to a smaller main and larger drogue if required.

I've also had some concerns about the main chute burrito wrapped getting tangled as it'll be on the airframe/av bay side of the harness and not on the NC. So I'm hoping to mitigate that by weaving the kevlar recovery harness through the nomex a couple times so the harness is part of the burrito instead of separate to it. That should hopefully mitigate that concern.

Finally, given the expected apogee altitude I'm going to use aluminum cannon/cannons for apogee deployment. Ideally I'll have them recessed in the AV Bay but we'll see as real estate will be tight!

If you or anyone else can think of anything I've not considered I'd love to hear it. I'm not aware of anyone who's flown a design quite like this so any advice is welcome.

drew
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 26,850ft - L935 - THUNDA 2019
Max V - 3,004 ft/s, ~Mach 2.67 - L935 - THUNDA 2019

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Re: Full Clip - 54mm MD build

Postby vance2loud » Thu Oct 11, 2018 3:57 pm

If you are worried about shredding a drouge you could also consider the rocketman ballistic drogues, they come in a 1 foot size and are meant to handle deployment at speeds up to 1000 mph. So long as the rest of the recovery gear can handle it.
http://the-rocketman.com/chutes.html
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drew
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Re: Full Clip - 54mm MD build

Postby drew » Thu Oct 11, 2018 4:29 pm

Cheers for that vance2loud. I had looked at those but considering I can buy 4 Top Flight X-type drogues for the price of 1 12" RocketMan Ballistic Mach II drogues I figured it's worth it to check out the Top Flight offerings first. Basically I was concerned that using a Top Flight thin mill chute for drogue (my go to for small space MD chutes) wouldn't be strong enough for the jet stream. X-type/cruciform chutes have a low Cd which is an advantage for high speed drogues.

Image

From here.
https://fruitychutes.com/files/blog/NARCON%202013%20-%20Rocket%20Recovery%20Technology.pdf

Price breakdown.

Top Flight X-Types

X-TYPE PARACHUTES
2x XTPAR-10 10" $6.95 each
ULTRA-X-TYPE WITH FLAT-BRAIDED NYLON LINES REINFORCED
UXTPAR-18 18" $13.95
UXTPAR-24 24" $15.95
Total = $43.80 USD

Single RocketMan Ballistic Mach II 12" chute = $50 USD
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 26,850ft - L935 - THUNDA 2019
Max V - 3,004 ft/s, ~Mach 2.67 - L935 - THUNDA 2019

drew
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Re: Full Clip - 54mm MD build

Postby drew » Fri Oct 19, 2018 3:47 pm

Just a quick update, I posted on TRF regarding the Top Flight X-Type chutes and what speeds they can withstand. Preston Noble, the proprietor of Top Flight LLC, chimed in on the thread and it looks like I'll be getting him to make me two 10" Ultra X-Types.
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 26,850ft - L935 - THUNDA 2019
Max V - 3,004 ft/s, ~Mach 2.67 - L935 - THUNDA 2019

drew
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Re: Full Clip - 54mm MD build

Postby drew » Tue Apr 30, 2019 4:20 pm

Alright, time to update this thread.

Here's a photo of the components for this bird.
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And here's the business end of the AV bay (with deployment canister recessed inside it) and the fins.
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Tacking the fins on with the fin alignment guides.
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Airframe with fins and fillets beside the CTI Pro54 6gxl casing with tailcone.
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Fillet close up.
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Airframe + fins + fillet total weight (excluding NC and AV Bay)
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And finally it got a roughly 1/2 day stint in the easy bake curing oven.
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My post cure consisted of 45 minutes at 45 deg C, 1 hour at 55 deg C, nearly 4 hours at 65 deg C, then back to 55 for an hour, and finally 45 for one more hour.
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Next up - flight report.
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 26,850ft - L935 - THUNDA 2019
Max V - 3,004 ft/s, ~Mach 2.67 - L935 - THUNDA 2019

drew
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Re: Full Clip - 54mm MD build

Postby drew » Wed May 01, 2019 3:01 pm

Flight report

I decided to fly this rocket on Thursday for a number of reasons. First, I'd not tested the design before and figured starting with an L935 made more sense than the M2245. Second, I only took delivery of my M2245 on the flight line on Thursday morning. Given that motor requires grain bonding and ideally 24 hours for the glue to fully cure it was logical to fly this rocket first. The range didn't open until 1 pm on Thursday due to RAF exercises in the area. I was racked and in the air in under 40 minutes after range open.

A big thanks goes out to John for taking the below flight photos as well as George for providing them to me.
If it wasn't for them I wouldn't have had any stills from the launch other than from my video cameras.

Launch

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Recovery

Recovery was incredibly simple. I used AltosDroid with a TeleDongle to monitor the flight and then jumped in my rental with Mike P. to go and collect the rocket. In AltosDroid you can click on the "Recover" or "Map" tabs at the top of the app and the software will lead you right to your rocket. It reads out on regular intervals something along the lines of "bearing 20 degrees right, distance x km". This allows you to action recovery without having to look at the screen which is quite useful imho. The rocket landed roughly 3.2km from the launch pad. Mike and I drove to within 300 meters of it with a bearing of 90 degrees which ensured from the road we were within closest walking distance to the rocket. 100 meters into the walk I could clearly see my main and turned off the telemetry.

As you can see below, on landing I popped a fin.
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Here's a clearer view of the popped fin. The damaged fin was under the rocket.
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Flight data

Finally, here are some of the stats from the on board Raven 3 and TeleGPS.

Raven 3 summary.
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Raven 3 graph with baro altitude and velocity.
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TeleGPS flight summary.
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Google Earth Flight track.
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I've still got some video from the flight line as well as next to the pad. I'll end up editing them together into a youtube video and post the results here.

Some high level lessons from the flight.

1) The fly away rail guide worked as hoped. It was damaged in the launch and has a hairline fracture down the "C" side of the FARG. I'll take a photo of that and post it at a later date. I doubt I'll use a FARG again but if I do I will consider them a disposable/single use cost associated with the launch.
2) My drogue ended up a bit tangled. I'm unsure if it was due to my recovery design or just bad luck. I'll keep an eye on this in future flights with this style of recovery.
3) USB-C SUCKS. My TeleDongle was connected to my Pixel 2 via a USB-C OTG cable and it kept falling out as it doesn't really click or lock into place. VERY ANNOYING. I need to pick up a TeleBT.
4) Tip to tip is unnecessary for 54mm MD flights up to Mach 2.7 BUT if you want to keep the fins on for good consider a layer or two of CF t2t. If I had a layer of t2t I doubt I would have popped the fin on landing.
5) My CTI 54mm Tailcone was EAT UP by the L935. I'll post a photo soon but the inside of the base of the tailcone has chunks of the aluminum missing. The black anodizing also showed some discoloration at the base of the tailcone as well. I had flown it with a K300 without issue but I guess the L935 is at the limits of what that component can support.

Video and a few more photos soon.

drew
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 26,850ft - L935 - THUNDA 2019
Max V - 3,004 ft/s, ~Mach 2.67 - L935 - THUNDA 2019

drew
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Re: Full Clip - 54mm MD build

Postby drew » Thu May 02, 2019 12:33 am

Here's a video compilation I put together of the various media I had from the flight.

Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 26,850ft - L935 - THUNDA 2019
Max V - 3,004 ft/s, ~Mach 2.67 - L935 - THUNDA 2019

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Re: Full Clip - 54mm MD build

Postby air.command » Thu May 02, 2019 9:05 am

Very interesting data Drew, thanks for sharing. 61Gs is really moving off the pad. At what altitude would it have gone supersonic?
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Re: Full Clip - 54mm MD build

Postby SpaceManMat » Thu May 02, 2019 9:47 am

The noise coming off the pad :shock: Love it. 8)
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

drew
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Re: Full Clip - 54mm MD build

Postby drew » Thu May 02, 2019 11:10 am

air.command wrote:Very interesting data Drew, thanks for sharing. 61Gs is really moving off the pad. At what altitude would it have gone supersonic?


Thanks bud. According the Raven data at around 350ft AGL and 1.2 seconds into the flight the rocket broke Mach. And at 3 seconds into the flight at 4,750 ft AGL max V was reached.
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 26,850ft - L935 - THUNDA 2019
Max V - 3,004 ft/s, ~Mach 2.67 - L935 - THUNDA 2019

drew
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Re: Full Clip - 54mm MD build

Postby drew » Thu May 02, 2019 11:35 am

SpaceManMat wrote:The noise coming off the pad :shock: Love it. 8)


Thanks d00d, I couldn't agree more!
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 26,850ft - L935 - THUNDA 2019
Max V - 3,004 ft/s, ~Mach 2.67 - L935 - THUNDA 2019


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