Striker AGM Iris

I apologize for the format of the following page. It appears this poor Google editor has a mind of its own in determining font size, color and spacing. I make changes, and it comes out totally different. Believe me, it looks fine in the editor, but really stupid on the review!

The Striker AGM Iris: The Quest Striker AGM is a simulated military missile. My particular rocket was modified with a 3.5" payload that stretches it to over 30 inches long, therefore it is a variant with the Iris mission suffix.  I painted to an entirely different red-white-blue scheme featuring some gold trim lines. Another modification was started by the shipping company.

The body tube was damaged in the center, so I wrapped it with a heavy paper shroud and then strengthened the body with eight basswood strakes that looks more like it was meant to be a design feature instead of a patch-job. To hide it in plain sight the strakes were painted gold.

It looks like it was painted more for an air show and not like an AGM missile. I think with this model I have finally learned that models of this size and weight (30” and about 5 oz.) should have a 24mm mount. The 18mm motors that are affordable are just not powerful enough for satisfying altitudes. This should be strong enough to fly with a composite D10 motor.  Still, it does Ok with a C6-3 pushing it to 250-300 feet, and it doesn’t seem to turn into the wind much.

SPECIFICATIONS

Serial Number: 24

Number of Stages: 1

Stock Length: 27"

Iris Payload Length: 3.5"

Tip-to-Tail Length: 30.5"

Diameter: 1.375"

Fin Span: 6.2"

Secondary Fin Span: 3.2"

Stock Mass: 100.9 grams

Iris Modification Mass: 10.7 grams

Total Mass (dry): 118.5 grams

Liftoff Mass Range: 137.3 - 144.3 grams

Motor Diameter: 18mm

Motor Length: 70mm

Motor Mounting Method: Clip

Payload Interior Length: 3.7"

Payload Diameter: 1.34"

Payload Volume: 5.22 cubic inches

Altimeter Capability: Yes

Recovery Method: 14" Plastic Parachute

Recovery Protection: Wadding

Shock Cord Mount: Kevlar

Fins: 4 + 4, paper covered balsa

Body Tube Conduits: 8

Kit Brand: Quest

Completion Date: March 25, 2012

Recommended Motor(s): C6-3

PERFORMANCE FIGURES

Highest Altitude: 303', 92.4 meters

Fastest Speed: 73 mph, 107.1 ft/sec

Highest G-force: 5.5

Average G-force: 1.53

Typical Descent Speed: 10 mph

Longest Duration Flight: 25.3 seconds

Shortest Duration Flight: 13.8 seconds

Total Flights to date: 4

FLIGHT LOG

2012, April 1: Penn Manor, 5-10 mph winds, gusty

C6-3: This is the first, virgin flight for this newly-built model. I had to cross my fingers that the erratic wind gusts wouldn't destroy her. It is a tall and heavy model, as much as a C6 can possibly handle. No question I would opt for a -3 instead of a -5 delay. This particular C6-3 burned for 2.1 seconds and peaked at a respectable 5.5 Gs of acceleration, averaging only 1.5 for the burn - nearly as low as can safely be done, since a slow liftoff is prone to tipping into the wind. There was no gust at liftoff and the slow liftoff was a thing of nervous beauty. At about 50 feet a gust turned it slightly into the wind, maybe 10 or 15 degrees. The Striker reached a good speed of 70 mph and then coasted up for 2.9 seconds where the ejection charge fired at just the right time at 256 feet. It only gained another 3 feet after ejection.  It then descended under a good canopy at 10 mph to a soft, nearby landing in the grass. Successful, although the altitude was lower than I expected and leaves me with doubts about flying it with a B motor. A composite D10 would be very nice!

2012, May 6: Penn Manor, light wind

C6-5: Previously, on its maiden voyage, I sent this model up in gusty winds using a C6-3. For its second flight with the wind calm I thought I could get some extra altitude using a C6-5 with its 2 additional seconds of coasting. The actual delay for this motor was 6.2 seconds, much too much for this heavy model. The liftoff was fine, peaking at 5Gs, and the 2.1 second burn averaged 1.4Gs. At burnout it was traveling at 63 mph and coasted for 2.4 seconds to an apogee of 253 feet. The long delay of 6.2 seconds allowed the model to drop (rocketing straight downward) 160 feet in 3.8 seconds before ejection, so at an altitude of only 93 feet the parachute deployed correctly and with a loud snap. The Striker drifted to the ground at 10 mph. It landed only about 150 feet from the launch pad after a 13.8 second flight. Inspection revealed about 3/4" of zipper damage from the Kevlar cord (Kevlar is strong enough to slice through the body tube) while deploying at a high speed (probably about 60 mph).

Lessons: 1) This model is restricted to C6-3 flights only. 2) Make the Kevlar cord shorter than that supplied by Quest.

2012, June 10: Halifax, near calm

C6-3: I needed to send this up one more time to finish initial test flights and to prove that the C6-3 is the best motor choice for this rocket. The weather was very warm and calm for this flight. In the past I have measured over 5 Gs of acceleration for this model, but today it left the pad only peaking 4.5 Gs, however the average acceleration for the 2 second burn was higher than usual at 1.7 Gs.  This particular motor was a slow & steady burner.

It reached its highest recorded speed of 73 mph and coasted for 2.9 seconds to an altitude of 298 feet where the ejection occurred just a tad early. The rocket then stopped at 303 feet - the highest recorded for this rocket. The entire flight and coast was very straight up with little rolling.  The parachute deployed fully and the rocket then descended at 10 mph to a grass landing about 50 feet from the pad for a total flight time of 25.3 seconds. This was a perfect flight to start a very good flying day.



2012, Sept 1: Fort Indiantown Gap, PA, 10 mph winds

Quest C6-3: I have plenty of other rockets that need test flights, but this was different. Having just purchased my first Quest motors, I wanted to see how they stack up with Estes, which I have used almost exclusively.  I gave Quest the home-field advantage by choosing a Quest kit to fly it in.
I was surprised to find that this Quest motor did not fit into the Quest motor tube! The paper wrap made it tight and trying to force it in only bunched the paper up more for an even tighter fit. I had to rip off all of the paper wrap to get it to fit into the Striker.  This difficulty was confirmed by another more experienced Quest user.

While packing the parachute, I saw the knot on the Kevlar-to-shock cord and considered cutting away the excess to prevent it from catching the parachute, but then thought it unnecessary, even though I recommended exactly that in a recent review I wrote.


Eventually I got it on the launcher and fired it up.  This motor burned for two seconds, about the same as Estes. Interesting though, it produced about twice the acceleration at 10.9 Gs than a typical Estes C6. The average acceleration for the entire burn was a lot less, and less than Estes at 1.2 Gs. The rocket reached a top speed of 53 mph, which was 18 mph less than the average Estes C6.  It then coasted up to 242 feet and there the ejection fired late at 3.8 seconds. It continued up for another 12 feet and stopped at 254 feet at apogee.

The parachute was pulled out of the rocket but never did open up. It was tangled in a mess of Kevlar and elastic cord, and a shroud line was caught in the very knot I earlier decided not to fix with a simple snip of the scissors.

Without a parachute it fell at 16 mph, landing hard in the grass after a 15.6 second flight, about 250 feet upwind.  It landed sideways and tried to break off two fins.  The fins remained attached, but the glue fillet joints showed obvious cracks. These two fins will need to be removed completely and re-glued. A lot more trouble than a snip of the scissors.

Overall the big difference I see here is that the Quest motors peak out much more, but then burns slower and weaker then Estes.  As a result it did not go as fast or as high as an Estes C6. Further comparison tests are needed to prove or deny this claim.

As I should have done before, I cut the tails of the knots short, wrapped them tightly in string, and soaked glue into the bundle.  This should prevent the parachute from catching on the knot and (in this case at least) causing some more fin root edge cracks.


As for the fins, I have repaired them by re-gluing them to the body tube, and touching up with a little paint, but the crack and repair is still fairly visible.  The Striker is ready to fly again!


2013, October 6: Penn Manor (south field), 8 mph winds, 80 degrees


Quest C6-3:  This was the second flight using a Quest C6-3 instead of my usual Estes C6-3. The last flight was rather poor in comparison to Estes, but this time the performance was remarkably better, showing that the Quest motor can compete with Estes.

The Quest motor lit well and the peak acceleration off the pad was better than the Estes average reaching 9.3 Gs. The average acceleration was extremely low though, at only 0.9 Gs (above the terrestrial 1.0 Gs).  It was a very, very long burn time of 2.6 seconds, and the audible roar was much more impressive than any Estes motor, as it compared more with the sound of a composite motor.

In spite of the long burn time, it only reached a top speed of 58 mph, rather slow, but it then coasted for 2.4 seconds more, still travelling upwards at only a slight angle, reaching a second highest apogee of 297 feet (the record was 303 feet, while the average for Estes motors was 272 feet).

The delay grain burned a little long - 3.4 seconds, giving the Striker enough time to turn over and fall only 7 feet in the final full second before ejection. The Quest parachute opened well at 290 feet, and the rocket descended at 9 mph - a little slower than any previous flight. It landed nearby in the grass 26.6 seconds later. Inspection showed a fin cracked and almost completely separated at the root, even though it was a slow descent and a soft landing in grass. I suspect that the fin repair from the previous flight with no parachute was not repaired very well.

In summary my opinion of Quest motors has improved based on this flight performance, but I still find it strange that I have to remove the label to get it to fit in a Quest rocket. Even then it was very tight. I also have doubts about the consistency of Quest motors, given the wide performance difference between my first two motors. A third test flight should tell me a lot more.









Whatever caused the fin damage is a moot point. The Striker AGM Iris  is now repaired and showing a few more scars, even though I used a bit of blue touch-up paint.  I'm hoping to soon fly it again with yet another Quest motor and see if indeed it is a) capable of competing with Estes, and b) see if there is a reasonable consistency between the Quest C6-3 motors.

2014, May 24: Fort Indiantown Gap, 5-10 mph winds, 70 degrees

Quest C6-3:   Again I decided to go with my gut and ignore the official flight schedule.  I just repaired the re-cracked fin root of this rocket and wanted to continue comparing Estes and Quest’s motors. If I complete this third Quest flight, then I have three tests of each brand motor to compare.

The Quest C6-3 lit right up, and again showed its high initial impulse by accelerating at 9.1 Gs.  The longer and louder 2.8 second burn only averaged 0.8 Gs, showing how Quest motors are all “pop-and-roar”, without much thrust after the initial liftoff.

The record low acceleration average gave me the lowest peak speed of just 50 mph. This was followed by a 3.3 second coast delay, where it reached an altitude of only 198 feet.  Ejection came a bit too early, with the rocket gaining an additional 4 feet after ejection. Highest altitude was 202 feet – the lowest of any flight.

I should point out that the altimeter for some unknown reason showed “1202” feet – obviously an error, but I am guessing the “1” was just erroneous. It certainly looked like 202 feet or just a bit above ejection altitude (198 reported) and I would have to mark that down as the estimated altitude anyways.

At least I got a perfectly good parachute this time (using a much larger brand-new homemade ‘chute), and the rocket returned at a record slow 7 mph. Flight time was 25 seconds. The new 20” parachute proved much better than the stock 14” I was using.

This particular Quest motor measured lowest of all the Quest motors in all categories.  Using all six flights averaged, I would have to say the performance edge as far as energy goes to Estes. In addition, the Estes motors actually fit into Estes rockets without peeling off the wrapper, unlike Quest motors!  True: the Quest motors have a big advantage in initial thrust and that could be good for windy conditions, but even then it is overall slower – bad for windy conditions.

The advantage of Quest seems to be cheaper cost, louder thrust and longer burn time (which is more satisfying).  Both motors are quite similar and useable, but there are some differences.  Later I will be comparing the two C6 motors in different rockets.