Black Diamond Iris

The Black Diamond: This model is extremely fast and light, uses 1/2A to C motors, although I'm a bit afraid to try a C in this little gem. I imagine it could easily reach 1200 feet.  It features streamer recovery. Added a lot of nose weight to balance this model, but now it flies very straight and true even in windy conditions.

The above photo shows the rocket with the added payload section (in orange).
Here is a picture of the stock rocket.

I was a bit concerned about cardboard fins, but they are very stiff and seem to work well (I just hope they don't get bent!) This rocket was later given my "Iris" modification, which extends the body tube about 5 inches above the streamer/parachute bay, and allows for a payload with an Altimeter One to measure altitudes. With the added weight, I needed a longer, 4-foot long, 2-inch wide streamer to slow it down some.  Not so easy to squeeze into a BT-20 body.

I had to lengthen the shock cord also, but it is still getting quite beat-up by its own recoil force. (Iris is named after the Greek god of the rainbow. She is a messenger of the gods, linking the gods with humanity.) If I were to build another one, I would split the launch lug and glue half of it further toward the nose. As it is, it wobbles on liftoff some while on the rod. This rocket has flown higher than the Aon Center and the John Hancock Tower in Chicago, and the NY Times Building in NY, NY.

This is one of four models I have flown with the C6-7 motor. Of all those flights, this model achieved the highest speed, making 217 mph.

SPECIFICATIONS

Series Number: 15
Number of Stages: 1
Stock Length: 12"
Iris Payload Length: 4.69"
Total Length with Payload: 16.69"
Diameter: 0.736"
Fin Span: 3"
Number of Fins: 5
Stock Empty Weight: 30.7 grams
Iris Payload Weight: 5.4 grams
Empty Weight with Iris Payload: 36.1 grams
Liftoff Weight Range: 58 - 67.2 grams
Motor Diameter: 18 mm
Motor Length: 70 mm
Motor Retention Method: Friction
Payload Interior Length: 3"
Payload Interior Diameter: 0.71"
Payload Volume: 1.188 cubic inches
Altimeter Capable: Yes
Recovery Method: Mylar Streamer, 4'
Typical Descent Speed: 18 mph
Recovery Protection Method: Wadding
Shock Cord Mounting: Paper
Noseweight Mass: 6 grams
Fin Material: Cardboard
Launch Lug Size: 1/8"
Glue Used: Titebond III
Paint Used: Painter's Touch, Testors
Kit Brand: Estes
Completed: Dec. 4, 2010
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FLIGHT LOGS
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2011, May 29: Indiantown Gap, Light wind

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A8-3: First flight: Perfect Flight, Fast!  Took off like a rocket (no pun intended).  Streamer kept this in sight and nearby. Will try a B motor next, but I imagine with a C it will never be found. Altitude was an estimated 170 feet, there was no altimeter onboard.
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2011, July 2: Indiantown Gap, Light wind

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A8-3: First test with the altimeter payload, came down very fast! Needs a larger streamer or parachute to resist the weight of the added payload & nose-weight. Altimeter measured 184 feet.
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B6-4: Pretty good altitude for a B-powered model, making 529 feet. Good flight with a new streamer that should have been adequate, but this one melted a bit and twisted to the shock cord, came down fast. Plastic streamers are not good!
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2011, September 3: Indiantown Gap, Light wind

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B6-4: Good flight and recovery on streamer. Even this 2-inch wide 4-foot streamer fell a bit fast, so it should be safe to fly on a C-powered motor and not drift too far. Reached an apogee of 511 feet, wow!
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2011, November 6: Penn Manor, Breezy wind

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A8-3: Good flight and recovery.  Shot up fast and the wind didn't bother it at all with its small fins, but the burn was over in a half second and the streamer let it fall its usual fast 20mph. I should have used a B or C, but I was worried it would apogee at 1000+ feet and get lost. This particular flight reached 156 feet. This is a good windy-weather rocket.
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I lengthened the shock cord to about 2 feet, but it still snapped back and really scraped up the payload tube this time. A lot of the paint peeled off and it might have a kinked tube. Maybe the best recovery would be two separate streamers or small parachutes? This rocket reached 60mph and accelerated at a peak of 14.3 Gs (average Gs was 5.6). Ejection was only 2/10 second late and it only fell 4 feet. It was on the ground in less than 10 seconds.
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2011, November 25: Penn Manor, Moderate wind

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B6-4: First flight of the day, clear blue sky above. I wanted to send this bird up as far as she could fly with a but the wind seemed a little stronger than forecast. I opted for a B6 instead, even though it comes down pretty fast on a streamer. An Altimeter 2 was onboard. The motor fired-up and she burned for almost a full second, speeding the Diamond up to 123 mph. Rapidly accelerating, it reached 17.5 Gs before burnout.
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The Diamond continued straight up despite the winds while it coasted for another 5 seconds to 489 feet when the ejection fired. While the long, Mylar streamer was unfurling, she topped-out at 504 feet one second later. She then returned quickly to the ground at 18 mph, ending up in wet mud within 10 seconds. So far, this is the fastest rocket speed I ever recorded.
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2012, March 18: Penn Manor, Light wind

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C6-7: This was the first flight with a C6 motor in this rocket. I was hoping to set a new altitude record with the Black Diamond, since this proved to fly even higher and faster than the Sprint with B6 motors. However it came up a bit short, and the following flight with the Sprint ended up breaking it's own altitude record.
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The motor burned for 2 seconds, accelerating the rocket to a peak of 22.7Gs, averaging 4.9 Gs for the burn. It reached an incredible record-breaking speed of 217 mph, then coasted straight up and out of sight for another 6.7 seconds to a peak of 1160 feet. 7/10 seconds later the rocket descended 12 feet and the ejection fired.
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The empty casing was blown out of the rocket when the friction-fit failed.  I could hear the thick Mylar streamer flapping in the wind, but couldn't see the rocket until about 200 feet as it descended quickly at 21 mph. In the calm air, it landed only a few hundred feet away. Inspection revealed some wadding still in the tube, so I suppose it was a bit too tight causing the motor to eject itself.  Mostly a success. No altitude record but a new speed record was set.
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2012, April 1: Penn Manor, 5-10 mph wind, gusty

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B6-4: This high-performance rocket can handle gusty winds because it launches very fast and it's added length and nose-weight helps keep it stable with its small, thin fins. Also, having bad luck with parachutes today I was relieved to be flying a bird with streamer recovery. The B motor burned for 8/10 second, accelerating to a peak of 18.6 Gs. The rocket shot up straight as a laser.
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The average acceleration of 6.7 Gs is better than I get with an A8 or C6 motor. With this power, it reached a top speed of 121 mph and an apogee of 479 feet, not quite as good as a previous B6 flight. As in the previous flight, the ejection fired almost a second too early at 3.1 seconds while at 434 feet and while still coasting straight up for another 45 feet.
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The empty casing was ejected which I assume added to the vertical velocity. 8/10 seconds later it stopped at apogee before falling. The streamer unwound slowly and the rocket descended at its expected 18 mph to keep it from getting lost. It landed after a 20 second flight time. A good flight, although it didn't set any altitude or speed records. (Which is 529', 123 mph on B6 motors). A B6-6 would have flown higher, even in the moderate and gusty winds on this day.
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2012, June 30: Indiantown Gap, Erratic winds

B6-6: I was expecting a very hot and calm morning, but it was very breezy and gusty. All my planned high flights had to be scrubbed. The small, light Black Diamond with a streamer was ideal, able to get up in a hurry despite the winds and it recovers quickly. This rocket is less than 60 grams fully loaded, and with a B6 it accelerates fast but does not go too high.
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Today it peaked at 15.3 Gs and averaged 5.6 Gs for a 9/10 second burn. It reached a top speed of 115 mph. It then coasted for 4.9 seconds to 450 feet. It then fell 11 feet in the next 6/10 seconds and released its streamer. It then came back at a fast 16 mph to reach the ground only about 100 feet away after 24.6 seconds of flight. All was well.

This picture shows the shiny Mylar streamer glinting in the sun.
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2012, August 11: Halifax, 6-10mph winds, some gusting





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A8-3: It seems to always be windy on flight days, and on windy days I always go for the light, fast rockets. The Black Diamond is one of those rockets, powered by an 18mm but tips the scales at less than 40 grams. With the A8 motor she goes up in a tremendous hurry, and comes down almost as fast with the 4 foot Mylar streamer. The wind just doesn’t have time to react!
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Here is a sequence of pictures showing this flight's ejection sequence:

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Today she accelerated at a peak of 18.1 Gs, and averaged just over 3 Gs for the entire ½ second burn. These were the highest accelerations I’ve recorded with the A8 motor.  This got her to 60 mph just in that ½ second and she coasted to 153 feet where the ejection fired exactly as specified. The nosecone popped up the extra two feet to record an apogee of 155 feet, actually the lowest I ever got with an A8 motor.  The streamer must have unwound well  because the rocket descended at a slower than normal 14 mph, landing very near the launch area.
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2014, June 15: Penn Manor, 5 mph winds, 75 degrees

C6-7: We had eager spectators wanting to see a spectacular flight, but with a small field and winds a bit stiff, higher power flights were not deemed safe, so the best alternative I could approve was a second ever high-power test flight of the Black Diamond Iris.  This was not risky because of the high-visibility Mylar streamer would be seen and return quickly before the winds could carry it far.

With its small stature, light weight and fully loaded propellant, I knew it could fly very fast and very high, much more than any previous flight seen this particular day.  I hoped to set a Black Diamond speed or altitude record, but it came up a bit short.
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 The Black Diamond Iris breaking the 1000 foot mark.

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Initial liftoff acceleration was 15.6 Gs, and for its long 2 second burn it sustained an average of 4.4 Gs. These were not record numbers, but it still attained a top speed of 192 mph.
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 Ejection at 1083 feet above the ground.

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After a long 6.6 second coast, the ejection fired at 1083 feet, stopping the Black Diamond’s ascent. In that last 4/10 seconds it climbed another 6 feet to top-out at an apogee of 1089 feet.
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A longer delay would have allowed for significantly more altitude, but this motor only had 6.2 seconds in it.  It then descended the final 1083 feet quickly at a speed of 17 mph.  After a record-long flight time of 50.5 seconds, it landed in the grass with the booster right-side up on its rear fins, about 250 feet from the launch pad. All went well, and the spectators were suitably impressed.

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2016, April 17: Cross Keys Field NJ, 66 degrees, 34%RH, 5 mph winds, no gusts



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C6-7:  The Black Diamond hasn’t been up in almost two years, although the last flight and another flight a few years ago was also with the maximum size C6-7 motor.  With the calm winds and bright red Mylar streamer, I felt good about retrieving this rocket after it’s been 1000 feet up.
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Smoke and debris begin to surround the Black Diamond just after the moment of ignition.

Hang on fella's, this is going to be one fast, high flight!

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This C6 motor didn’t seem to have the get-up-and-go, as it fired off the pad with only a peak acceleration of 11.8 Gs – lower than the other C6 flights.  Its average acceleration was also low at only 3.8 Gs; The lowest of any motor in this rocket.
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 With it's diameter barely wider than the 18mm motor, and its cardboard-thin fins,

the Black Diamond slips through the air with little resistance.  Even with a 1/1000 shutter speed,

this model is starting to blur only inches after it started moving.

This model was modified with a slender, long, and bright orange payload section to make it easier to see when 1000 feet up.  It also holds a special visual surprise for us when it gets there.

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The light weight of the Diamond was able to allow it a maximum speed of 180 mph.  I was expecting more since this is has broken 200 mph previously.  At least it burned long, for a whopping 2.2 seconds, so it was able to coast for 5.7 seconds to an altitude of 949 feet.  Again I was hoping for 1000+.  It could have done that but seemed to turn into the wind above about 500 feet or so.
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I was glad to have a nice video of this rocket arcing away from the launch pad like it began maneuvering to get into a parking orbit.  "Off we go, into the wild blue..."

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Ejection charge came one full second later after the rocket descended 23 feet.  It has never delayed this long after apogee so I guess that is a record for this rocket.  I could see the tracking smoke but little else until the streamer unfurled below 926 feet.  The bright red sparkle against the blue sky showed its location.  It descended at its usual fast rate of 19
mph.  I wish it would have been a bit slower because it landed about 450 feet upwind.
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When I follow the rapidly moving path of this rocket with my camera,

the relative lack of motion makes it less of a hit-or-miss in getting a fairly clear image

...remember this is accelerating to 180 mph, and that's pretty fast. 

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After a good walk, I found it with the nosecone buried half way in the soft earth like a lawn dart.  Aside from a little dirt on the nose, it was fine.  Successful flight number 3 for the day is in the log books, and flight number 12 for this rocket.
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The Black Diamond Iris at rest. Notice the nose cone & payload section stuck right into the dirt.  It was a pretty hard landing with the mass of it only being retarded by a streamer.

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I noticed the hard landing allowed the plastic cover of the altimeter to continue towards the nose cone after the circuit board and internals stopped because it was tight against the nose cone.  This happened before, and didn't permanently destroy the altimeter.

 

 

 

The button and LCD display is displaced in the plastic housing.  I had to push it back in place with a pair of pliers before I could press the button to read the data.

 

2019, April 7: Penn Manor, 70 degrees, 10-15 mph winds, gusty


 



A8-3: This was the first launch of 2019, and it turned out to be a pretty windy
and gusty day yet unseasonably warm at 70 degrees F.  There was no chance of
launching high flights, but that’s fine because I wanted to send Black Diamond up
for a third low-power flight.
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With the light weight and high speed of the Black Diamond, winds are not a
problem.  It can reach an apogee before the wind has a chance.  It’s even better
that it uses a streamer.
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This rocket lifted off well, accelerated off the pad at 15.7 Gs, and averaged 5.7
Gs for the ½ second burn.  In that time it reached 57 mph, then it coasted for
2.7 seconds more.  After peaking at 149 feet, it turned and only dropped 2 feet
before ejection at 1/10 second later at 147 feet.
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We've seen this before, where the rocket appears to be launched right by a school building.
This is only a illusion of perspective you get with a very long telephoto lens.
In reality there is a whole soccer field length and more between the launch area and the school, as the two goals suggest.

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The bright and glossy red streamer unfurled and it returned at 16 mph to land in
the grass upwind about 50 feet.  I didn’t secure the motor all that tightly, and
the casing ejected at altitude and fell unseen in to the grass.  The flight was
over in only 9.6 seconds.
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The Black Diamond Iris landed so close to the launch area,
this picture of it returning was captured by the very same camera that took the launch photo.
That was not expected!

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This was the Black Diamonds’ lowest flight, slowest flight, and shortest coast-to-apogee.  Most likely because it was also the shortest delay time the Diamond
ever had to deal with.
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that's all for now...
#rocket #modelrocket #blackdiamond