This ol' girl sure made a lot of flights and she's showing her age. In the early days this was my tallest and most impressive rocket for the first year or two, so I would really like to get her flying again and see how high it can go, I imagine close to 1000 feet.
To restore this model, I needed to find a clear BT-50 payload tube since the old one is cracked. I don't recall it cracking during a flight, it most likely occurred while in storage.
The good news is that I found a clear payload tube. I gave up hope of ordering the part from some internet site. Even Estes doesn't sell many individual parts now like they used to "backintheday". I ended up with an extra tube from a kit I bought for parts. Now there is hope to have this rocket restored by winter 2012.
November 2012: I have now begun the process of restoring this old rocket. This was possible because I have a leftover clear plastic tube from an Estes Magician, which has the same diameter and length as the X-Ray rocket. As you can see here, the old plastic was yellowed, brittle and cracked. The new one looks like lead crystal in comparison.
From the moment I opened up the parachute compartment, the old, brittle rubber shock cord was crumbled and fell out in pieces. A new one had to be installed. The original one was attached to a pair of slits in the body tube, so instead of repeating that, I glued a small loop of Kevlar thread to the inside of the tube about an inch down. I can use this loop to tie the shock cord using a small fishing swivel clip. There is not much room to work on this, as the main body tube is only about 1/2" in diameter, too small to get more than one finger in there.
Here I will show you the completed repair with the Kevlar loop. I purposely mounted it below the end of the tube so I will not have to worry about zipper damage from an early or late ejection. Kevlar is such a strong material, that at high speeds it will slice right through the paper body tube if given the chance. Having the rubber shock cord at the end prevents this. I chose to use the shock cord material as supplied by Quest, since it has a braided cloth sheath around the rubber core. Although it doesn't stretch quite as far, it appears to be more durable. Only time and a lot of test flights will tell.
The old 12" stock parachute had to go, it was just too old, crinkly and had weak attachment points.
Another interesting item I discovered when I was restoring this old payloader, was that the screw-eye which attaches the rocket and parachute to the payload was not ever glued in! Just a few threads into soft balsa kept this payload from being lost forever!
I made sure to glue it in well this time, and as I learned from experience never to trust the screw-eye-to-balsa glue, I added my small Kevlar thread glued through the eye to act as a back-up if the threaded joint fails.I don't want to lose another $70 altimeter.
To this I attached the new shock cord and a smaller parachute. Since this is a light rocket a 9 or 10 inch chute should be enough and will help prevent it from being lost by drifting away in the winds.
The static vent holes were drilled in the new plastic for the altimeter, and new padding was created to hold the device in securely without rattling or banging around in there. Black electrical tape was used to provide a snug fit to the transition and nose cone.
The X-Ray is now fully restored and ready for its first flight in 35 years. A new yellow plastic parachute was made for it with a diameter of only 9.3", and 50% longer shroud lines. (the original one measured 11 inches, although Estes claimed 12" for it). Here it is with the Altimeter One installed in the payload section.
Out of the six different models I fly with the A8-3 motor, this model holds the record for both highest altitude (231 feet) and highest speed (76 mph).
SPECIFICATIONS
Series Number: 4
Number of Stages: 1
Length: 16.75"
Lower (booster) Diameter: 0.736"
Upper (payload) Diameter: 0.976"
Empty Weight: 23.6 grams
Liftoff Weight Range: 45.5 - 54.7 grams
Motor Diameter: 18 mm
Motor Length: 70 mm
Motor Retention: Friction Fit
Payload Interior Length: 3"
Payload Interior Diameter: 0.95"
Payload Volume: 2.126 cubic inches
Payload Tube Material: Clear Plastic
Fin Circular Span: 3.875" diameter
Altimeter Capable: Yes
Recovery Method: 9.3" Plastic Parachute
Recovery Protection Method: Wadding
Shock Cord Mount: Kevlar
Nosecone Material: Balsa Wood
Number of Fins: 4
Fin Material: Balsa Wood
Launch Lug Size: 1/8"
Paint Used: Pactra Aero Gloss Dope
Kit Brand: Estes
Completion: about 1975
FLIGHT LOGS
(Estimated about 12 flights on this rocket back in the 1970's)
2012, November 23: Penn Manor, moderate wind
The A8 motor lit and the rocket shot to the sky fairly quickly and straight, peak acceleration was 21.9 Gs (it can only measure to 23 Gs). The short burn of the motor was done in ½ second, averaging 7.7 Gs during that time, allowing this classic rocket to reach a maximum speed of 76 mph. It then coasted for 2.7 seconds and reached apogee, 216 feet above ground. I was pleased it was able to resist the growing breeze.
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2012, December 2: Penn Manor, 7 mph wind, no gusts
.A8-3: This was the second test flight of the just-restored X-Ray, carrying the Altimeter 2 in its transparent payload section.
The burn was good, lasting ½ second and accelerating this light rocket at 21.2 Gs off the pad and it produced an overall average of 7 Gs for the burn. She hit a top speed of 75 mph and coasted for 2.6 seconds.
At that time, the ejection charge fired off 4/10 seconds too early, the rocket was at 217 feet – just a foot higher than the last flight's apogee. This time it kept going for another 14 feet before heading back down from 231 feet. This flight set a new altitude and duration record for the X-Ray with the A8 motor.
The parachute opened fully, bringing the rocket back at 7 mph. After a 22.7 second flight, it landed in the grass about 200 feet downwind. Estimating that I could get 540 feet with a B6 motor, I had to scrub the next test flight because the winds were too much.
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2014, August 2: Halifax, 5 mph winds, 80 degrees
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A8-3: I really wanted to fly the X-Ray on a B6 motor, but having come a bit
uncomfortably close to the tree line with a previous flight, I chose instead to
re-do a flight with the A8, where the previous flight had a soft ejection and did
not trigger the ejection timing.
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After a good ignition, the X-Ray had a low 19.7 Gs of acceleration off the pad,
and the 5/10 second burn time averaged 6.6Gs. That was only good enough to push
the rocket to 72 mph, all record lows for the A8 motor.
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It then coasted up for 3 seconds to a perfect delay time, and ejected at 203
feet, while continuing upwards toward 209 feet in the last 4/10 seconds. That was
also a record low apogee for the A8 motor.
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A good parachute brought the X-Ray back at 9 mph, landing about 100 feet
downwind. Flight time was 18.5 seconds, also record low. Not a very impressive
flight according to the numbers, but it was a flawless flight – third one of the
day – and that could be considered impressive.
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2019, April 7: Penn Manor, 70 degrees, 10-15 mph winds, gusty
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A8-3: The X-Ray was going up again for a re-do flight because for unknown
reasons I did not get an apogee-to-ejection time previously. This flight
followed the wind-capable Black Diamond, and like the Diamond, this is light,
fast, and will not be too bothered by the strong winds and will not reach too
high.
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My original ‘ray took to the air like a champ, reaching a neck-snapping 17.2 Gs
off the pad, and over the course of a ½ second burn, averaged 6.2 Gs of
acceleration. In that half second it was travelling 68 mph. All these numbers
bested the Black Diamond, likely because it doesn’t have the nose weight of the
Black Diamond.
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After a 2.9 second coast, and while still not at apogee, the ejection fired at
183 feet, stopping the rocket 1/10 second later at 206 feet altitude (or 23 feet
higher).
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A small 10.5” parachute opened up, and with its 10% spill hole, it returned at 8
mph to land about 200 feet downwind (across the road into the next field). This
was a 19 second flight. It was only luck that it didn’t snag the single electric
wire by the road. One other rocket this day wasn’t so lucky. (The club doesn’t
always choose the best launch point based on the winds, today launching directly
upwind of these electric wires!)
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Out of the four modern-era flights of the X-Ray – all A8-3 flights - this was the
lowest, slowest, and least accelerated flight. No different from the other
flights today.
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| The moment of ejection captured at about 200 feet above ground. |
Ironic: I flew this today because I didn’t get a reading from the Altimeter.
Today I did get all numbers, but neglected to record the flight time. The 19
second flight time was determined from a video taken of the flight.
.
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| After a good parachute opened. The spot on the left is some wadding from the rocket. |
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2019, May 25: Fort Indiantown Gap, 5-10 mph wind, 70degrees
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B6-4: After being restored, this was to be the first flight of the X-Ray with a
higher power motor, having only flown with A8-3’s so far. This was delayed
because the rocket is so light, and altitude was expected to reach beyond 500
feet (540 predicted), and there was no low-wind opportunity until this time. I
prepared this rocket with a 10.5 inch chute with a spill hole.
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I may have not used the best judgment flying this rocket on this day. And though
the flight was a disaster, it wasn’t because of my decision to fly such a small
rocket in a field with tall grass. Still, I should have known better. I also
should have chosen a smaller chute, though that wasn’t the problem either.
.
The flight started off well with a powerful 22.7 Gs of acceleration which was
better than any A8 flight. In the 8/10 second burn it averaged 7.4 Gs, and took
off very quickly while ignoring the growing winds. This pushed the rocket to a
best ever recorded speed of 137 mph, and still the rocket held together and flew
fine.
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Next was 3.3 seconds of coasting time. Then at 506 feet the ejection charge
fired, and this is where the trouble began. I don’t know if the ejection was too
powerful, but the refurbished shock cord was made with swivel clips on both
sides, and the side connecting to the Kevlar loop and not the parachute/payload
side, failed when the clip wire pulled straight out.
.
It is unclear whether the wadding might have been too tight, but that would not
have likely caused the swivel clip failure. Stuck wadding may have over-
pressured the body tube, but wouldn’t have necessarily made for a stronger
release when the parachute finally did eject, and it did eject. This brought the
rocket to a stop in the next 2/10 seconds, but not after gaining an additional 45
feet, reaching an apogee of 551 feet, (only 11 feet higher than predicted, just
saying.)
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In any event, I tracked the model coming back – or what I thought was the entire
model, but at 500 feet up only the parachute was visible, not the body tube.
Because of the separation it was falling unseen. What I thought to be the entire
rocket eventually came back, but at a leisurely 6 mph, giving me plenty of time
to worry if it would drift out of sight. It was drifting pretty far out. The
strong spiral motion I saw was a clue that there was a wadded parachute or a
broken shroud line.
.
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| This extremely magnified image shows the payload returning with a damaged parachute. I was tracking this with the camera, but at about 400 feet up and a few hundred downwind, I couldn't tell that the body was not attached. |
56.9 seconds later it did eventually land. I found it without too much trouble
in very tall grass. It was not easy to spot but I happened on exactly the right
area. Had I been off by ten or twenty feet in the tall grass I might never have
spotted this small rocket.
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When I did finally put eyes on it I was a bit glad to see the payload, but then
quickly horrified to find both a damaged parachute (1 shroud line missing), and
no body tube.
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Next there was a protracted effort to walk the entire area of tall grass,
including much uneven, swampy, muddy areas in tall grass, in search of the body.
I figured it would have landed nearby, or somewhat closer to the launch area. I
never found it. In hindsight it make sense that it would have landed closer, but
the closer area was clear and if it did land there it could be spotted more
easily.
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I knew I would then spend the day searching for it, so I went back to return the payload, getting a drink and prepare for a long search effort. Since this was one of my original 1970s rockets I didn’t want to just write it off so quickly. It was a classic and only the fourth rocket I ever built or flew.
In hindsight, I wish I would have aborted the preliminary search sooner, because as I arrived back at the launch site, a flying partner George handed me the body tube, saying that it landed right near his car – parked next to my car – which was about 50 feet upwind of the launch pads.
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While relieved that the search was over, I was disappointed to first spot the familiar brown ball with grass pieces sticking out the end. What I saw was the end of a crumpled body tube from this core sample. I was even more disappointed to take it and find a large spiral split along the body tube seam. This rocket was seriously damaged due to a failed clip. It could have over-pressured, maybe the wadding was packed too tight in the small 18mm tube, but I’m thinking that it was much more likely that the split was from the core sample, since there was no wadding stuck in there, and stuck wadding would not explain the bent steel wire clip that nearly caused its loss.
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| How can a B6-4 pack such a powerful punch to rip the wire clip right out of the catch? My only explanation was that maybe it got caught on a parachute shroud line (the one that broke). But still - that seems to be an extreme amount of energy to do this amount of damage. |
The only possible other explanation that might work for me is an extremely powerful ejection charge which I’ve seen before. That could have split the tube, ripped open the swivel clip, and possibly torn a parachute shroud line. Either that or simply a failed swivel clip lead to all the damage. With no evidence of stuck wadding, I blame the clip.
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the end.
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