2.6in Fiberglass L1/L2 Build

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BlazingAngel665

Propulsion Lead, Agile Space Industries
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Brief background, I grew up in Kansas. There wasn't a NAR or Tripoli group nearby, so I did things solo. I started with monthly runs to a hobby shop about an hour and a half away to pick up packs of Estes motors. Eventually I started doing custom propulsion. I did this for about three years. I realized that my large field and lack of neighbors was about to go away and needed to find a club to fly with. This meant getting certified.

This story starts in June after my first supersonic flight. I decided I had reached the limits of my phenolic tube and balsa wood roots and that I needed an all fiberglass rocket. My first stop was
OpenRocket. By that evening I had a roughed in blueprint for a rocket.
QiKznRw-n2TFD7-ZAF8q6oSZovFSXuUdWkQDZGLnrsaAdiQCv9zxv-bF4mC4iggs8bWUmX-331ZtyOyzn0gzUYsVHMZQeSMXoYOmNqobrFceq3f1U-qPkfZZiMHCn-rjdlcBOmoF

(Ignore the buggy CoG calculation, it thought my booster section was massless at the time)

The design was based upon Madcow Rocketry’s excellent Black Brant II. I’m a big fan of the boat tail on this rocket. The thin walled fiberglass tubing was also excellent quality. I am less of a fan of the conical nose cone, so I replaced the nose cone with a 4:1 ogive one. My next change was to stretch the fuselage to accommodate the longest 38mm motors. The airframe is now long enough for a 6GXL case and a drogue. Finally an avionics bay and forward fuselage made the rocket even taller and added dual-deployment capability. With the design complete, orders went out to Madcow Rocketry, Apogee Components, and Amazon.
Over the next week parts began to trickle in. My room began to look suspiciously like the Vehicle Assembly Building. Unfortunately, life intervened at this point in time, and I only had a few free weekends before September. I assembled the motor mount, but that was all. As I left for college my rocket parts migrated with me. I joined MIT's rocket team. We go out to Amesbury, MA and Burwick, ME, for launches.
With the first team launch quickly approaching, I needed a rocket. With a few tubes of 5 minute epoxy, a box of parts, and some good friends I entered the workshop at 1 pm.
I walked out ten and a half hours later, carrying a flyable, but still very incomplete rocket.
rW4AuvUam81CkXTm8RKOtCjcTswgKDYErM4MHnWOO2771-xxGrRAtU5vL8K7aa0lV07mOxcjFpwLa7AUGRCd2Zcxf6miSu1z  H3FKeO3nOibirsL88_MB5vmWABRi8sWjrpfFBE8m
I borrowed electronics from Rocket Team. The first flight had a Marsa 54L and a Stratologger CF. The parachute is a 30in nylon chute. I'm not in love with the final decent rate of about 10m/s. It seems too fast. One of these days I'll put a larger chute on the vehicle. The drogue is a 12in.
The rocket flew under the pseudonym “Albino Beaver” in homage to it’s semi-transparent body and MIT’s mascot. A picture perfect flight sent the vehicle to 1050ft. A bystander was kind enough to video the launch and find me on the internet to share the footage. That video is [video=youtube;ivNKMSJnqeU]https://www.youtube.com/watch?v=ivNKMSJnqeU&index=1&list=FLgBqAFriBrftRkj304eiiVw[/video]. Or a picture:
WlSAIaNVgGLwBQ7_RDIURSPWTxzcK-ONkLUWIg2WkKkluI6vOvBAWU9VxsiUz27Zq5byN17PDyIiLEPq  qHmr_g7f75h7b6M4PdB0U6WLZe_b8nSKz55ZForg6xwpMaEDEV  8c4wCa
Unfortunately, my fin application didn’t survive the landing. One fin popped out. It was a quick fix, but I decided to reinforce all the fins with a fiberglass overlay.
In theory, overlays are awesome, but in practice, I need practice. My overlay turned out so ugly that three coats of bondo, five coats of primer, and four weekends worth of sanding were required to restore the rocket to a presentable state.
qDkKGxI6E9OkG3UewyxHcgp5xL6cpyEkfMkmLtSSBecCa6SBsQ  9sLrfcNmXimwzeY176Le4Ou7AYaGGunmKqp6OFnjsT_KJhpQID  z94-G8a3ZebLeDtaWyJhfcBGD39qCv6P10DP

With the fins firmly attached, I turned my attention to the electronics suite. The original av bay was a piece of balsa wood with a circuit board zip tied on one side and a battery on the other side. This sufficed for a mid-power flight, but was insufficient for anything more powerful. To remedy the av bay I added a camera, a backup battery, an arming switch, and connectors to the avionics bay. This all attached to a 3D printed sled.
1O2kuEN9-cZy_whBOd3rbMBOxGABXzFkw3niVxXEMBFSINX4i-2nuSLtiDIuPsiiMRJPHNPb47zpFvPxAImvi_4UER1uvmCIGQjx  Y1Eh-V4q-NCVeGJhePUg2BDDTyUVNCyb7Xgt
The Arduino Uno underneath the red flag is an avionics payload that is preparing for a test flight. It sends back live telemetry via an Xbee wireless radio. It will be tagging along on my next flight.
The camera is an 808 #25. It runs about $11 from various online retailers. It is light and cheap, but I’m underwhelmed by its behavior. Sometimes it decides to take an unscheduled day off. Other days it works fine. I highly recommend the Marsa. It’s easy to use and very functional. The Stratologger is a mainstay of the hobby, probably due to its reliability. On my rocket it’s purpose is purely as a redundant backup. Power comes from 2 9v batteries. The Stratologger gets one to itself, to make sure I get my rocket back. The Marsa, GPS, and transmitter share the other.
The red flag itself is one of my favorite features. A small microswitch is held by the sled. The switch is wired as normally closed. Two washers create a small channel for the pin attached to the flag. When the pin is inserted, the switch opens, deactivating the Marsa and the Stratologger. This system allows me to keep the pyros off and disarmed until the rocket is ready to launch. The remove before flight tag makes the whole system look and feel professional, despite being mostly cobbled together.
DljKygoerEpp69VwPnL4J0jfXT8S2XrTkmmsxbc6CnESF9yGvO  YRdePJKTYNnne8RGMY-byGkWHwrycmeAkyldCpWvNc1l3LiZrKf350oqh2n07WlqqjS6i  lsUuzNfr29x5ne8eL

This is the whole rocket laid out on the integration table. It’s ready to fly. The only thing left to do is to give it a name and a paint scheme. Hopefully, I can be slightly more creative than on my first attempt.
tWixCpiM1O-zDJ17tm_YSrhyrLDIhlDIOz5Xbq9vVcgkW3TX0YqGwZG4B3yfU  gvwILd8h6H0JvWK2t2NUm7uTSvH01JpXgKIY_WbfpmTvr_Q7bz  nVtsxoBeUWDxSrwPPsr6909nY
(Flight Ready)

What do you think guys? I'm taking her out for the third time this Saturday. I'm aiming to get my L1 cert if the fins will stay on. (trapezoidal fins, I know, but these look so nice)

 

kjkcolorado

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I think it's awesome! Make it look pretty.... get some paint and maybe some decals on it. If you haven't already, take a look at StickerShock23.com. Mark can do a lot with vinyl decals (lettering, designs, etc). Not sure he has a picture of an 'Albino Beaver', but you can always ask.
 

BDB

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It looks great. I'm hoping go to the CMass launch on Saturday too. I'd love to see the Albiono Beaver in action.
 

eggplant

L3 | NAR 93664, TRA 17791
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I had a hunch that I had seen this rocket before just from the title, and I was right! I have my fingers crossed for the next attempt, and I'm sure it will go well for you! It's all about that surface prep.
 

kjkcolorado

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Oh, it looks like you have room to stick a bigger chute in there. if you aren't in love with the descent rate provided by the 30" chute, and have the means, get a bigger chute. Be nice to those big fins so you can fly this bird (or should I say 'Beaver') for years to come.
 
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Igotnothing

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One thing to consider as you move to longer motors is that putting the main chute in the fwd bay helps the CG. (Drogue in the aft bay.) Another thing is that a 6 grain 38 might send a 2.6" rocket pretty high. A bit of drift from a mile up means a long retrieve. In that case, I would remove the drogue entirely and let the rocket fall in two halves connected by your shock cord until the main is deployed. If you do that, get some 2-56 nylon screws and use 6 to fix the upper bay to the nose cone, 1-2 to pin the upper bay to the av-bay, and one to fix the av-bay to the booster. Ground test your ejection charges will reliably separate the chute bays from the av-bay at apogee and whatever altitude you select on the altimeter for the main.

Somebody is going to say, "That's too much for someone still pursuing L1 cert!" I am going to respond, "MIT for cryin' out loud."
 

BlazingAngel665

Propulsion Lead, Agile Space Industries
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@BDB, hope to see you there!

@Eggplant, I've got my fingers crossed too. If this breaks I'm going to get L brackets and bolt my fins on. I'm dead serious. Kelly got some and they are in lab.

@kjkcolorado I'm either going to put a larger chute in ( 50" should do the trick ) or put a second 30" in. I'm not sure how flying multiple chutes works in terms of drag or spacing. If nothing else it might be a fun experiment.

@Sinful Darklord, not sure what the trouble is. . . maybe I'll host a couple on imgur.

@Igotnothing, The main is in my forward bay for DD. Originally I was using motor ejection charge for redundancy. This became unnecessary with the addition of the stratologger, so I moved the chutes around. My CG is probably already a little too far forward. My vehicle can be quite over-stable on small motors (good stability off the rail though). I've though about my long walks for retrieval. Telemetry is already working, so finding it shouldn't be a problem, but something MIT's rocket team is working on is an actuated parafoil for guided landings. If we get that working I'd like to implement a scaled down version of the system. That is fairly long term though. Near term I'm packing hiking shoes. As far as sheer pins go, I have two on the nosecone/forward fuselage joint, I have two on the booster/av bay joint. I have three pop rivets in the av bay/forward fuselage joint. Ground testing verified the back of the envelope calculations for 2.5g BP.

I have a "J" impulse limit and a 3k ft ceiling at Amesbury due to field limits. Burwick is clear up to 10k, but I can't quite make it that high according to sims. If I did fly that high I would consider going for tumble drogue or streamer drogue. I'm not overly concerned about trying too much for this attempt. I have been around for a while, the newest thing to me this project was the marvel that is reusable cases.

Side note: MIT is a marvelous place, but I'm not sure what magic powers it grants. I've made my share of rookie mistakes, just usually on rockets a few years ago where nobody could see them. My L1 is weird because I've done all of this before, just by myself. Seeing and hearing other's people's take is great, and launches are a lot more fun, but the vehicle does the same things.
 

tigerstripe40

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Nice build! I am building this rocket kit myself currently. I had a questions for you.
Did you cut the original body tube down at all?
How long is the extension tube you used?
 

BlazingAngel665

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@Tigerstripe40, nope, didn't trim it a bit. I'm pretty over-stable on small motors, but it isn't a real issue. I used a 16in extension and the fiberglass AV bay from Madcow. I switched the nosecone to a 4:1 ogive.
 

blackjack2564

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The only thing I might suggest:

GPS & radios generally are a bit power hungry, sharing a single 9v. between the GPS & altimeter may result in short life.

I would waste a battery on the ground by powering those 2 units up & timing actual battery life.
Mine lasted 68 minutes [GPS] by itself. Had I ran it to an altimeter it surely would have been less.

Hence in my application I went with 750ma LIpo which lasts 10hrs is half the size of 9v.
For you if time does not allow...simply adding another 9v. would cure the problem....IF one becomes an issue.

Otherwise you have done a fine job on your project. Good luck with the flight.
 

BlazingAngel665

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I figured I'd give an update to this. I've flow 7 flights on the rocket, now called "Eager Beaver." Those flights included my L1 and my L2 (lost my stupid papers in the rental car though, so I'll have to refly it). Here are some flight pictures from URRF 3.
4A4ves7.jpg

Fiddle
7mlh72U.jpg

more fiddle
91JVGDS.jpg

dramatic pause....
Then fail to take any ascent pictures. . .
xKatjzA.jpg

Successful landing. These soft fields are great for cert flights.

The avionics has been upgraded to a TeleMetrum 2.0, which does in flight telemetry. It's really cool, totally worth the money. The pull pin switch has proven to be a pain. I got epoxy on the contact when I was gluing it. The pin looks nice and professional when I pull it out though.
The fins have been a constant pain. I probably didn't do enough surface prep on them. After flight 4 I did a tip to tip layup. That helped tremendously.

IMG_20160625_150708082.jpg

IMG_20160625_144832012.jpg

IMG_20160625_144730897_HDR.jpg

IMG_20160625_144713066.jpg
 

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