TRF Summer Build Off: Babylon 5 Starfury

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No recovery implemented yet but had to rush off to the launch site this morning: Moffett Field at NASA Ames. The LUNAR people running the show were extremely friendly, helpful, efficient, & professional as always! Tons of people and lots of flights but we only averaged a flight every 45min or so.

Had to jury-rig the kevlar, elastic, & 12" parachute with minimal tools (18" wouldn't fit). I only had B6-4's suitable but the delay felt way too long. Does anyone know how difficult it is finding B6-2's? I had no luck trying to swap with people so B6-4 it was, and I was able to get her in at the end amidst curious onlookers. Got the blessing of the RSO and set up at a distant pad. There was a slight breeze but I angled her straight up with her belly to the wind.

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5... 4... 3... 2... 1... <silence>

?!??? The LUNAR staff were helpful and offered a fresh starter.

5... 4... 3... 2... 1... psssst!

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She shot up stable and started arching on her back away from the wind, up to perhaps 200ft (250?), and started arcing back down. As predicted, a 4 second delay was too long and a 2 second would've been better. Much relief as the chute popped at about 50-70ft and she came back down. Some nice person (I believe LUNAR president David R) was nearby and stuffed the parachute back into the body to prevent the rocket from being dragged across the concrete. There was some minor damage to ion suppressors (at the rear) and one of the front engine caps but not much else.

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So, the boilerplate starfury is a success! :) :) :)

ps - The starfury weathercocked away from the wind. ??? Something to do with the air deflection of the top cowling when the belly (no cowling) faces the wind? The front of the cowling is angled down and it's hollow underneath with an air channel there. I don't think the wind direction changed but it might have. Weight and/or drag imbalance between the top & bottom, perhaps?
 
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After-thoughts:

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Recovery setup:

- kevlar tied around one of the washers in the bolt, and below the forward, double centering ring (pain w/o tools);
the front centering ring is doubled for strength & to help keep the motor mount from binding.
the kevlar should be long enough to allow the motor mount to clear the back of the ship's ion suppressors to prevent damage.
coil the kevlar around the top of the motor tube. The thrust ring opening needs to be big enough for the nut/bolt combo to pass.

- elastic tied around one of the side supports (portside, for me), and between the motor mount centering rings.
this elastic should be quite long, and definitely longer than the kevlar, to prevent damage from the nut/bolt combo swinging back.
zigzag the elastic packing; do not wind it around the motor mount.

- remove a small divot at the side of the rear centering ring, closest to the externally tied elastic to allow room for the elastic to pass.

- used a 12" chute as I couldn't fit the 18" chute. Loop or tie it onto the elastic close to the motor mount.

- pack the chute so it will deploy rapidly when the motor mount ejects.


This starfury should be the XSA-23-1 as a proof-of-concept boilerplate. Its proportions are pretty close except for the nose/cockpit area, the wing sweep, minor wing details, and the ion suppressor angles. The current configuration is 69g w/o motor. Updates should include:

- using balsa instead of corrugated cardboard
- add the smaller, inner ion suppressors; they should help with stability but I ran out of time.
- change the nose weight arrangement (BBs, sinkers, etc.) to something that doesn't need to recess inside the motor
- correct the front of the lower wing shape
- add lower armaments/cannons/detail + add more upper cannon details
- build a more accurate cockpit area
- add directional thrusters on the main engine pods
- ??? perhaps shorten the motor mount & thrust ring slightly?

- ??? perhaps build more accurate "double-decker" wings? Don't know about this one. It may add a lot of weight and that's really, really bad.
- ??? perhaps extend the main body length & parachute compartment spacing?

Adding weight is going to be a problem unless I move to an 18mm composite. It was really, really difficult stuffing the 12" recovery into that tiny space so moving to 24mm is out unless I can get the starfury to glide. or I suppose a slight upscale would help for 24mm since everything was scratch built from corrugated cardboard, cardstock, and paper anyway.

Of note, I did try swing testing a C6-3 with the nut/bolt nose weight earlier on. The motor stuck out about 0.5" more but the starfury still seemed stable. This was before I started adding all the details.


Anyway, this was a fun project! It's my first real build since BAR'ing over 1.5 yrs ago. Thanks again to Scotty Dog for getting me motivated, and thanks also to OpenRocket and the USPS! :) Maybe I'll go back to some 3/4FNC + upscales before tackling another unconventional design.

Hope you all enjoyed reading this. Comments, questions, and/or suggestions are welcomed! Thanks!
 
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That is AWESOME! :clap:

Seemed to hold up well on landing considering the hard surface. As far as arcing away from the wind, perhaps its an effect of the asymmetric main body? A bit more deflection on the flat side? If only one had easy access to a wind tunnel...

Keep us updated, I like where this is going.
 
With all the weird angles and surfaces on that thing, it seems like it would be incredibly easy for some of them to be not quite symmetrical and cause the rocket to deflect. The real way to verify would be to fly it in different orientations relative to the wind, and see what it does. If it always arcs the same way, regardless of wind direction, then it's probably asymmetry in the build. If it always goes the same way relative to the wind, then... well I'm not quite sure what it means. :)

I'm really impressed that you got that to fly as well as it did, I had my doubts. If you get one all painted up it should really be a very cool model, very unique. Well done sir.
 

That is AWESOME! :clap:

Seemed to hold up well on landing considering the hard surface. As far as arcing away from the wind, perhaps its an effect of the asymmetric main body? A bit more deflection on the flat side? If only one had easy access to a wind tunnel...

Keep us updated, I like where this is going.

Thanks, dhbarr & Cabernut! Yes, a wind tunnel would definitely help here. Maybe I can create a makeshift one. I'm not sure I'll build another starfury anytime soon but may continue adding to this one. It was a lot of work by hand.

With all the weird angles and surfaces on that thing, it seems like it would be incredibly easy for some of them to be not quite symmetrical and cause the rocket to deflect. The real way to verify would be to fly it in different orientations relative to the wind, and see what it does. If it always arcs the same way, regardless of wind direction, then it's probably asymmetry in the build. If it always goes the same way relative to the wind, then... well I'm not quite sure what it means. :)

I'm really impressed that you got that to fly as well as it did, I had my doubts. If you get one all painted up it should really be a very cool model, very unique. Well done sir.

Thank you, neil_w, and you & Cabernut are right, it's quite asymmetric across the top/bottom. I'll have to pick up some B6-2's first since it almost cratered with a B6-4.

One of the club officers got a video of the flight which was very stable aside from the arcing. I'll link or post it here if I can get permission.
Thanks for the suggestions & the interest! :)
 
I have some not-even-napkin sketches for a combination wind tunnel / curing oven....
Cool! Estes listed a design for a basic wind tunnel (no curing oven) a long time ago (1965?):
https://www2.estesrockets.com/pdf/2845_Classic_Collection_TR-TN.pdf

Apogee too + companion article:
https://www.apogeerockets.com/education/downloads/Newsletter252.pdf
https://www.apogeerockets.com/education/downloads/Newsletter345.pdf


FLIGHT VIDEO:
I got permission to link the flight video! It was shot by LUNAR past-president & current NAR section advisor, Jack Hagerty, on the LUNAR Facebook page. Thanks, Jack!
Uh, how does one embed a Facebook video?

https://www.facebook.com/jack.hagerty.3/videos/10208735753486252/
 
Cool! Estes listed a design for a basic wind tunnel (no curing oven) a long time ago (1965?):
https://www2.estesrockets.com/pdf/2845_Classic_Collection_TR-TN.pdf

Apogee too + companion article:
https://www.apogeerockets.com/education/downloads/Newsletter252.pdf
https://www.apogeerockets.com/education/downloads/Newsletter345.pdf


FLIGHT VIDEO:
I got permission to link the flight video! It was shot by LUNAR past-president & current NAR section advisor, Jack Hagerty, on the LUNAR Facebook page. Thanks, Jack!
Uh, how does one embed a Facebook video?

https://www.facebook.com/jack.hagerty.3/videos/10208735753486252/

Those are some excellent resources. I've got some reading to do...
 
Second flight report: yesterday, 3/11/2017 at the Snow Ranch in Farmington, CA with LUNAR. The grassy lands were spacious with some gently rolling hills, some streams, a few trees, and landmines from the local cows. The weather was warm and slightly overcast with a breeze. It was my first time out there and the hosts were very friendly and extremely gracious. Definitely much appreciated! :)

No winds at ground level in the shallow, flat launch area between the close hills. The unmodified starfury took off straight using a B6-2 this time. At about 50', it turned abruptly horizontal into the winds as it cleared the hill cover and appeared to "glide" for a moment before popping its 12" parachute. No damage. It was really neat to see it hang in the air.

Normal weather cocking seems to be a bigger issue here than asymmetric weight & drag so I'll need to collect more data. Potential causes of the arching maiden flight could be rod tip-off from a slightly misaligned motor mount; I still had trouble packing the laundry and may not have packed it tight enough the first time to engage the rear centering ring. Note to self to make more room on the next version.

I plan to add more details to this model, and wish I had more opportunities to launch & test. Will post updates along the way.

PS - I'm not used to the new Estes starters yet and only had a 60% success rate compared to the 95%+ of the old ones.
 
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