The 6th Observable

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Dotini

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This C11-3 powered model is almost finished, and I'm asking for feedback as to the final paint scheme.
Right now, it's 4.8 oz, so I have another ounce or so until I hit my limit of 6 ounces.

My default paint scheme right now is to leave the two ends black, the middle white (or orange) with a long chrome mylar stripe, and the ring clear.


DSC00247.jpg
DSC00249.jpg

Model consists of fin unit, extension tube, recovery system section, ejectable nosecone/payload bay. BT55 diameter, length about 40".

I'll be out at my remote fishing cabin for a day or two, so I'll respond to any replies when I get home.
 
The areas that are white can be colored with highlighters, yellow, orange, pink, blue, green.... I’ve even seen lavender. The first three colors are very visible. The weight cost is negligible, and it can be done indoors without much regard for temperature and humidity. From 10 feet it’ll look good. More importantly, from a couple hundred feet orange or pink should be more visible than white (not sure how much risk there is of landing outside of direct site from launch pad.

I think that PURE backsliders are FAR more sensitive to balance issues than horizontal spin rockets. Adding a streamer however will probably buy you enough leeway to do a decent paint job.
 
This C11-3 powered model is almost finished, and I'm asking for feedback as to the final paint scheme.
Right now, it's 4.8 oz, so I have another ounce or so until I hit my limit of 6 ounces.

My default paint scheme right now is to leave the two ends black, the middle white (or orange) with a long chrome mylar stripe, and the ring clear.


View attachment 467187
View attachment 467188

Model consists of fin unit, extension tube, recovery system section, ejectable nosecone/payload bay. BT55 diameter, length about 40".

I'll be out at my remote fishing cabin for a day or two, so I'll respond to any replies when I get home.
Yellow and orange show up really well at distance, especially if they're fluorescents. Is chrome stip for a roll pattern? Good idea, the flash/reflection will really help track it.
 
I really like your fin unit. Tell us about the clear tube fin - how did you make it? What kind of adhesive holds it in place?
 
I think I've been playing with toy lightsabers too much lately but that clear fin unit would look rad with some led light dispersed through it. This would probably mess with your weight too much though.
 
I've decided to do a lot of my rockets with black NC and fins and yellow or orange body, all for visibility against blue or gray skies. An airbrushed yellow/orange finish would be cool.

Love the clear fin ring. Made me realize that every rocket I've seen like this has had full fins. What would be fun to try is using clear acrylic rods TTW to the MMT and snapped into holes in the ring so the entire fin can would essentially disappear. It would require a lot of precision in the build but would very cool to fly.

What is the source of your clear ring?
 
I really like your fin unit. Tell us about the clear tube fin - how did you make it? What kind of adhesive holds it in place?
I've decided to do a lot of my rockets with black NC and fins and yellow or orange body, all for visibility against blue or gray skies. An airbrushed yellow/orange finish would be cool.

Love the clear fin ring. Made me realize that every rocket I've seen like this has had full fins. What would be fun to try is using clear acrylic rods TTW to the MMT and snapped into holes in the ring so the entire fin can would essentially disappear. It would require a lot of precision in the build but would very cool to fly.

What is the source of your clear ring?
Thanks for your questions about the fin ring. I cut it with scissors from an "ultra-thin" PETG shipping tube of 3" diameter and .020 wall thickness. It is both flexible, tough and does not crack. In previous models, I have used only a small variety of adhesives on this material , including original Gorilla Glue, Gorilla Super Glue and RTV sealant. I intend to use Gorilla Super Glue on this model, applying at least two drops to each of the six fins. The ring is a nice snug fit over the fins. The material will never break or tear, but it will come off if abused enough. It does not hold paint terribly well.

What is your length to diameter ratio?
It is about 30:1
 
I think that PURE backsliders are FAR more sensitive to balance issues than horizontal spin rockets. Adding a streamer however will probably buy you enough leeway to do a decent paint job.
For at least the first few flights, this rocket will use conventional parachute recovery.

Since I haven't used a parachute in well over 30 years, I'm asking some advice:
1) Will an Estes 15" diameter plastic chute be an acceptable way to recover this rocket? That's the largest I have in inventory. The weight of the complete ready-to-launch model is expected to be about 5 to 5.5 oz.

2) If not, what would you recommend?

All replies are welcome.

Edit: I've discovered an 18" Estes chute amongst my old kits.
 
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It will be interesting to see the effect of a chute compared to a streamer.

My SWAG* is it will paradoxically spoil your Back Slide by putting TOO much drag on the nose cone (actually, that part is good) and the forward end of the rocket. The net effect is that a chute may convert your desired Back Slide into a traditional (yawn) chute recovery, and your rocket will descend near vertically tail feathers down.

Still will be a unique rocket. I haven't seen a clear ring fin before. Nice repurposing!

*SWAG = Scientific WAG
 
It will be interesting to see the effect of a chute compared to a streamer.

My SWAG* is it will paradoxically spoil your Back Slide by putting TOO much drag on the nose cone (actually, that part is good) and the forward end of the rocket. The net effect is that a chute may convert your desired Back Slide into a traditional (yawn) chute recovery, and your rocket will descend near vertically tail feathers down.

Still will be a unique rocket. I haven't seen a clear ring fin before. Nice repurposing!

*SWAG = Scientific WAG
Do you think my chute is big enough? I'd like to keep it as small as possible to mitigate too much drift. After X number of successful flights, I will convert it to a backslider.
 
Do you think my chute is big enough? I'd like to keep it as small as possible to mitigate too much drift. After X number of successful flights, I will convert it to a backslider.
Yes. Descent will be a bit on the fast side, but well within tolerance, especially if you'll won't be landing on particularly hard surface. I've certainly used 15" chutes with 5 oz rockets.
 
Your design is somewhat optimized for a slightly rapid descent. If it truly falls tail first vertically the motor hook and the motor casing take the first hit. Examples of rockets that are NOT optimized for this type of landing include the Estes Alpha and Big Bertha.

for a small field, and a rocket of your design, I think 18 fps is a good compromise.
 
The ring is well located with 12 droplets of superglue. Is more really required for strength?
DSC00250.jpg

Almost finished, I intend to jazz visibility up with chrome mylar tape.
DSC00252.jpg

The 6th Observable complete with 15" chute, C11-3 and altimeter is 5.07 oz, less tape.
It is 1.33" diameter and 37" in length. About how high should I be expecting this to go?
 
About how high should I be expecting this to go?
Not too high. Six fins and the ring tail will be pretty draggy. I mocked up a quick equivalent in Rocksim. 130' with an optimal 1.8 sec delay. Stability margin is 5.67 with engine loaded, seriously overstable. Don't fly this in windy conditions.

Let us know what you actually get. Rocksim doesn't do the best sims with ring tails and tube fins....
 
Not too high. Six fins and the ring tail will be pretty draggy. I mocked up a quick equivalent in Rocksim. 130' with an optimal 1.8 sec delay. Stability margin is 5.67 with engine loaded, seriously overstable. Don't fly this in windy conditions.

Let us know what you actually get. Rocksim doesn't do the best sims with ring tails and tube fins....
Thanks for your calculations. I would have guessed five times that much. If 130' is all it can do, I won't bother with visibility tape.
 
Not too high. Six fins and the ring tail will be pretty draggy. I mocked up a quick equivalent in Rocksim. 130' with an optimal 1.8 sec delay. Stability margin is 5.67 with engine loaded, seriously overstable. Don't fly this in windy conditions.

Let us know what you actually get. Rocksim doesn't do the best sims with ring tails and tube fins....
Note, the total area of my fins and ring is about 17 square inches. That is about the equivalent area of 4 fins, 2" x 2.13".

My experience with Animist II, 2.53 oz, B4-2, seen below, was an altitude of ~345'.


DSC00253.jpg
 
Your designs not only fly great theyy LOOK great!
Thanks! But don't look too closely - they are nothing like museum quality. As for flying, I've sometimes pushed the boundaries too far and had a few turds and miscreants. At 72, I like to innovate, but copy shamelessly, set small goals, and avoid D motors and up. I believe in Roger Penske's 6P's - "proper preparation prevents piss poor performance".
 
I have arthritis of the knee and can't walk too far for my recoveries!

Back in my youth, I had launches with D, E and F motors which completely blew off what I thought were properly glued and filleted fins, and had some beautiful models on first launch leave Earth never to be seen again.

In my old age, I seek painless rocketry.
 
D and Es don't necessarily go higher or require longer walks. You just need slightly larger/heavier/draggier rockets, but still comfortably within the framework of LPR build techniques.

Frankly, I find building at a slightly larger size to be much easier on my eyes and hands, easier to track in the air, and *much* easier to stuff parachutes and wadding. Many of my rockets will stay in the 500'-600' range on a D12.

But anyway, it's your choice and by all means do what you prefer. I just thought that was an odd self-imposed restriction.
 
D and Es don't necessarily go higher or require longer walks. You just need slightly larger/heavier/draggier rockets, but still comfortably within the framework of LPR build techniques.

Frankly, I find building at a slightly larger size to be much easier on my eyes and hands, easier to track in the air, and *much* easier to stuff parachutes and wadding. Many of my rockets will stay in the 500'-600' range on a D12.

But anyway, it's your choice and by all means do what you prefer. I just thought that was an odd self-imposed restriction.
I have a very convenient place to fly only minutes away, about 500' x 600'. I would greatly enjoy the noise and smoke of flying a D motor there if it would stay under 600'. Maybe you could steer me to such a design? I have a large quantity of BT60/70 parts and pieces on hand that I don't know what to do with.

(I'll be offline at my fishing cabin for a day or two.)
 
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Maybe you could steer me to such a design?
BT60 and BT70, target weight in the 5-6 oz range, add draggy elements. Use OR to manage your altitude.

My designs tend to have a lot of decorative crap on them, so they're usually pretty draggy.
I have a large quantity of BT60/70 parts and pieces on hand that I don't know what to do with.
Build rockets. :)
 
I... avoid D motors and up.
I have arthritis of the knee and can't walk too far for my recoveries!
That's fair. Neil is right about drag and weight keeping D motor flights low, and...
130' IMHO is unsafe. I'd better go with a D12-3.
You're willing to use D engines when it's necessary. You're doing it right.

(Also, at your age many people have alternative recovery devices called "grandchildren".)

As for the reflective mylar stripe, if you don't think you need it for visibility (I agree) that doesn't mean it wouldn't still look good. Maybe a metallic gold stripe or band (or two) on that orange body.
 
Something that may work better would be a long metallic streamer.

rationale:

you are going for “assisted” BackSlide recovery. To me, that means you are going to pop the nose and deploy “something”. What you want to avoid is ballistic recovery, in which the CG remains forward of the CP after ejection. With a very long rocket, your problem if you are going to have one is the nose weight. So if you have enough streamer to support the nose (I.e., enough that the descent of the nose alone with the streamer equal to or SLIGHTLY less than the descent rate of the rocket fins and body in BackSlide Mode) the body of the rocket will go horizontal and do a slow draggy backslide with the streamer holding up the nose cone AND slowing down the horizontal speed of the backslide. For a small field rocket, this is actually ideal. My arrow straight backslides were cool but a bit concerning because those puppies covered some ground flying laterally. Ghost Rider was fortunate, had a slight turn (and that was dumb luck.)

long streamers (over 10-1 length to diameter) per Stine’s book don’t buy much in slowing descent, but they DO provide better visible clues to FINDING the rocket once down (in a tree or a bush or even deep grass ) as a portion of the streamer is likely to be ON TOP of the surroundings.

what you DON’T want is for the streamer to be TOO effective, meaning drag slows nose cone MUCH more than the “natural” BackSlide descent rate of the body tube. If THAT happens, the tail of the rocket body drops and you have a standard recovery.

that said, nothing wrong with flying it as a standard rocket once or twice, you can always “dial back” the drag (smaller chute, replace by streamer, smaller streamer, etc) for latter flights. Not as good to try to “dial forward” after a ballistic recovery with a crimped body tube, or worse.
 
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