The C-Thru is a novel new rocket being built from a kit from New Way Rocketry. What is unique about this rocket? It is SQUARE! It is square all over, so I had to get it.
Also it is small-to-mid-powered, and has a payload section already, so this was for me. Bonus: the payload section is clear, and I am hoping to use it with a camera, but the plastic is not optical quality. Still, I can easily add a flat glass window to this square rocket without the hassle of matching the radius of a conventional round tube. The clear payload means I can also install a light for night flying.
It is powered with a 29mm motor, so I can use a larger D motor to get the extra payload weight airborne.
Here you can see the motor mount being built, behind that is the square tube that it will go into. This was a high-quality kit and you can see here that the motor mounts are plywood. The slots in the tube are for mounting thru-the-wall fins. Having them mounted thru the tube produces a stronger bond than just gluing them on to the surface.
Considering this model may reach about 150-200 mph, the winds across the fins will be stronger than many hurricanes, and approaching a tornado in velocity. We can't have them coming off in flight or the rocket will become unstable and lose control very quickly.
The motor mount was installed in the main body tube and the fins were attached. Notice the theme C-Thru includes the 'C' shaped fins, which you can 'see thru'. The fins will still need glue fillets, to smooth out the transition between the body and the fins. This reinforces the joint, and also reduces air resistance which occurs at right angles such as these. It also makes the finished model look better.
As I started doing to all of my new construction rockets, I paper laminated the fins to provide a better, smoother finish without all the sanding & sealing effort. It also adds a bit of strength to the fins.
I rounded the leading edges, and tapered the trailing edges, but not so thin of a point to easily get dinged. I didn’t do that to the smaller forward fins because they are pretty small. Notice that the square theme extends to the launch lug. It’s square, but sized to fit a normal 1/8 inch launch rod.
On the block to the payload, I added the screw-eye to attach to the shock cord. I’ve lost a payload section before when the balsa failed where joined to the glue, so now I add extra glue to a Kevlar cord that goes thru the eye. If the screw breaks loose, my hope is that the Kevlar piece will hold it. I don’t want to loose a rather expensive mini HD camera.
I also securely attached the rubber shock cord to the Kevlar shock cord and soaked/coated it with glue. Another hard lesson learned is to clip those small tails that are hardened by the glue. I didn’t on one model, and the ‘chute got stuck on it and didn’t open. The rocket fell fast and broke a couple of fins.
Below we see the shaped nose cone, also somewhat square. Nice quality, but the kit’s cone didn’t exactly fit the clear (and squared) plastic payload tube and the instructions ask you to sand it to fit well. No problem. I suppose that the tube is subject to manufacturing variations, and no single balsa shape will fit well to every tube produced. I think that’s better than a poorly fitting nose cone. (nose pyramid?)
Here is the cone with the first layer of primer. Later, I will mask and paint white and red. These colors were chosen specifically to make this rocket easy to see during recovery. I don’t want to loose the expensive payload which will usually include a camera and altimeter.
White primer and paint was applied to the entire rocket. Yes, I didn’t bother to sand and fill all the tube seams that were fairly pronounced on this special square tube. I didn’t even fillet the leading fins as seen here. After all, this is a working utility rocket, not a shelf decoration.
Once painted white, I added the masking and painted red on various surfaces. I used cellophane tape with some heavy paper, which seems to produce a much cleaner edge without the paint leaking under the seams. It is harder to remove though, so I make sure to fold over each piece to leave a small tab to pull the tape off.
The shape of these fins and the two-color scheme I went with made the masking process very difficult. I made alternating sides of red and white, with contrasting red and white sides of the fins.
Below you can see the design taking shape with the masking removed. I had a precision masking job getting the nose cone right, but it worked out well with very little bleeding under the tape, thank you cellophane!
The payload section requires special custom work. I need it to hold a camera and an altimeter in the same section, so I built a light weight structure to keep each piece in place. Yes, I probably put a few more bits of wood in there, but I’d rather it be too strong than too weak, and all those little pieces will look cool when seen through the clear payload compartment. Here’s the altimeter in the bottom half:
And the top half holds the mini camera, up against a glass window on the side of the square tube. The camera is positioned to get a horizontal view of the horizon as it flies up, and not looking down at the ground. I want landscape vistas, not exhaust smoke pictures.
This is the completed structure before painting.
I also made a small balsa fairing to hold a tiny mirror. I’ll add this when I want to get a more traditional view looking down the rocket body.
Here we see the finished payload. The Nylon screws on the bottom of the clear tube are part of the kit that holds the payload tube. I thought it was a good idea to make sure the payload is secure so I added screws to the top cone also, and imbedded nylon nuts into the balsa on each side. I also cut out a hole where the camera lens looks through, and overlaid it with a small glass window. It is sealed with some silicone caulking. Not pretty, and a bit lumpy, but at least I will have optically clear images. I’m only hoping it doesn’t break in flight (landing I assume). We’ll see…
Here are two views of the finished product with decals attached. Hope she flies well!
SPECIFICATIONS
Series Number: 29Kit Manufacturer: New Way Rocketry
Stock Weight (empty payload, with parachutes, no wadding, no motor): 118.9 grams, (4.19 oz.)
Payload Structure & Window additional weight (over stock kit): 14.2 grams, (0.5 oz)
Overall Weight with Modifications: 133.1 grams, (4.695 oz.)
Altimeter Weight: 6.9 grams, (0.243 oz.)
Camera Weight: 37.8 grams, (1.33 oz.)
Total Liftoff weight (D12 motor, Camera, altimeter, parachutes): 179.2 grams, (6.32 oz.)
Number of Stages: 1
Overall Length: 24” (609.6mm)
Body Width: 1.375” (34.93mm)
Main Body Tube Length: 16” (406.4mm)
Fin Count: 4 + 4 forward
Total Fin Span: 4.67” (118.6mm)
Forward Fin Span: 2.9375” (74.6mm)
Payload Internal Length: 4.5” (114.3mm)
Payload Width: 1.31” (33.4mm)
Payload Volume: 7.75 in2 (127cm2)
Static Vent Ports: 4, 0.032” dia (0.813mm)
Motor Mount Diameter: 24mm
Motor Mount Length (clip): 70mm
Recommended Motor Sizes: D, E, F
Recovery: Dual Nylon Parachutes, 14”
Recovery Protection: 6”x6” Nomex Cloth
Shock Cord Material: Kevlar & Elastic
Launch Lug: 1/8”
Glue Used: Titebond III
Paint Brand: Rustoleum Painter’s Touch 2X (red, white), Testor’s (gray)
Modifications: Paint Scheme, Paper Laminated Fins, Dual Nylon Parachutes, Nomex Cloth, Chute attachment point on nose cone tip, Clear Glass Window, Payload Top Screws.
Start Date: Aug 3, 2012
Completion Date: May 21, 2013
FLIGHT LOG
Photos from these rocket flights can be seen in the page Aerial Photography
2013, June 30: Indiantown Gap, light wind.
D12-3: For this first ever flight, I used the recommended motor. I intended to fly this with a 47 gram payload weight. I made one with padding to exactly fit inside the payload section and not bounce around, but duh, I forgot to leave space for the altimeter, so I flew without any dummy weight (which I intended to use to simulate the camera weight to be carried next time). I also wanted to test a unique parachute configuration, which was carried on this maiden flight.
The D12 lit up fine, initial acceleration was a healthy 12.5 Gs, and the 1.8 second burn averaged a stout 3.2 Gs. The trajectory was super-straight up, a good thing for later camera flights.
The C-thru reached a top speed of 131 mph, then coasted for 2.8 seconds. The motor had a slightly early ejection at 2.6 seconds, while the rocket was at 589 feet and still travelling upwards with no arc. In the last 2/10 seconds it continued up another 40 feet, finally stopping at 629 feet apogee.
I could see a parachute but it was falling a bit faster than expected. It was a good thing I used a special parachute configuration. Apparently the main Nylon parachute (18”) melted at the shroud attachment points, literally “gluing” the parachute shut so it couldn’t be opened. The square corners of the body tube let too much ejection escape around the wadding/dog barf. The instructions warned me about this, but I guess I didn’t take enough extra precautions to fill the corners.
Well these things happen, and expecting something like this could occur, I had a second, smaller (9”) reserve chute attached to the payload section directly, since I was going to be launching a rather expensive camera. I had carefully attached the two chutes with enough distance apart between the very long shock cord so they would not likely interfere with each other.
The C-Thru came down at a fast 14mph, which would have been ok landing in the grass. But of course it landed on the hard gravel road with a loud thump, motor casing hitting first. This is a fairly heavy but sturdy frame, and I did not see any damage to the end of the rocket. Whew! Total flight time was 31-1/2 seconds, not that quick since it fell from over 600 feet. Next flight, I will bring a camera along and will certainly use a Nomex blanket for the parachutes!
The fellow club-member who was bringing some custom-made Nomex sheets for me did not show up at the launch – he had to work, so I had to make the attempt to make wadding work for this next flight.
2013, August 31: Fort Indiantown Gap, 3-6 mph winds, 86 degrees
D12-3: After a mostly successful test flight, it was time for the specially-modified C-Thru to go on a photography mission. It was carrying a tiny 47-gram HD video camera. Early in the day when it was sunny, it still seemed a bit hazy so I postponed the flight waiting for the morning fog to burn off. Later in the day it did, but unfortunately it was replaced with sunless overcast skies. Figuring any picture is better than no picture, I sent it up anyways.
The initial test flight showed that the square tube leaves gaps between the wadding and the corners, so I ended up with a burned Nylon parachute that was melted shut.
Fortunately I also secured a small 9-inch emergency parachute to the expensive payload. I did the same for this flight. I also packed it with some tissue wadding, then a layer of dog barf, another few squares of tissue, more dog barf and a final layer of tissue wadding. There musta' been a good three or four inches of wadding in there.
The D12 started burning, pushing the rocket off the pad at 9.3 Gs. It burned for 1.8 seconds while averaging 2.5 Gs. Pretty good considering the several ounces of electronics on board. As it fired up, it started rolling to the left a bit, then began rolling to the right at least one or two rotations, but still going pretty straight up. At motor burnout it was travelling at 101 mph. It then coasted to 461 feet where the ejection fired just 2/10 seconds early. With the momentum, it continued up another 8/10 seconds and climbed 24 feet to an apogee of 485 feet.
All that wadding blew out and appeared as though it exploded, but still the main chute was charred and didn't open at all. It remained on the end of a long shock cord in a tightly packed bundle. Again the emergency 9-inch parachute attached directly to the payload saved the day. The rocket returned at 13 mph, landing in 27.4 seconds. All was safe as it rested about 200 feet from the launch pad.
Nothing was damaged and the resulting video was fine. The considerable turbulence from the failed parachute made this video quite shaky, sometimes blurred, and often directed at the lifeless, dull gray sky. This rocket certainly needs a good Nomex sheet. Hopefully I can come up with a solution to the turbulence before the next nice, sunny day.
2014, May 24: Fort Indiantown Gap, 5-10 mph winds, 70 degrees
D12-5: It was a beautiful day for launching rockets, although the wind was a bit breezy. But it was a very good day for aerial photography – very clear and not hazy. I decided to launch my video camera in the C-Thru before anything changed.
Previous flights showed that despite the manufacturer’s suggestions, the C-Thru would do better with a 5-second delay instead of a -3. Both of the previous flights ejected about 1 second before apogee, which may have been a factor for the parachute issues I experienced.
The C-Thru was loaded up to 190 grams, since it carried an altimeter and a video camera in a modified payload. The payload weight alone made it surprising that it would need extra delay time, but it did.
This flight is the first test with the payload/recovery system re-configured so that the payload & camera remains upright while descending, thanks to a shock cord attachment on the nose of the rocket.
The rocket lifted off with a healthy 11 Gs of acceleration, but the stronger winds turned it about 30 degrees into the wind. It averaged 2.6 Gs for the 1.7 second thrust time, and at burnout it was moving 97 mph.
After a satisfyingly long 4.6 second delay, it ejected the parachutes, though still traveling upwards a bit. The ejection was measured at 405 feet, with the final apogee at 427 feet, so it gained an additional 22 feet in the last 1/10 second of the flight up.
One of the two parachutes became a bit tangled in the shock cord so it did not open fully. The other chute was fine and brought the payload back at 14mph. It landed safely in the grass about 150 feet upwind. It was a 25 second flight.
The pictures were quite clear, although there still was significant blur on the way up and spinning on the way down. Though having the payload section suspended from the nose thru a swivel helped, it was not the magic solution to perfect videos. It still swung under the chute too much.
On this clear day, it was the pixel resolution of the camera and not the haze that limited the view. Since I could not view or monitor the video in the field, I decided a second flight was needed to ensure I took some good photographs.
D12-5: Second flight was planned pretty much the same as the first. For starters, it was confirmed that the -5 delay was the best choice.
The second motor appeared much weaker than the first. It lit fine, but seemed to accelerate slowly – giving me ample time to track it with a hand-held camera. Peak acceleration measured only 7.3 Gs which was the lowest of all 4 flights so far. The average was only 2.4 Gs – also the lowest. Burn time was nominal at 1.8 seconds, so it was not a slow burning motor. It seemed more like a motor without a full charge.
The trajectory up again turned about 30 degrees due to the stronger upper winds, and the weak motor still was able to push this rocket to 94 mph. After 3.3 seconds of coasting upwards, the rocket turned over after hitting an apogee of 391 feet, and then continued downwards for the next 2.5 seconds due to a long, 5.8 second delay charge.
Ejection was at 340 feet, having descended 51 feet below apogee. This time both parachutes deployed fully and finally brought this rocket back the way it was designed to return. The payload remained mostly vertical and there was plenty of horizon pictures taken in the descent, which was only 12 mph, making for a 26.7 second flight.
Here is the C-Thru as it was intended to return; both parachutes open.
The rocket body hangs below everything, and is the first to touch down.
Suspended between the parachute and the body, the payload section remains vertical and upright. Note the parachutes are attached to the nose cone, and not the shock cord between the payload and rocket body. The Nomex is flapping below the payload. With the camera in the top half, its lens was clear of the Nomex.
This was the lowest and slowest flight of the C-Thru, but also the first with a perfect recovery. It landed in the grass about 200 feet away.
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2016, September 3: Fort Indiantown Gap, 73 degrees, 10 mph wind, gusty.
C11-3:_This was going to be a first-ever low-power test flight of the C-Thru, and for safety reasons it was not carrying the 38 gram mass of the camera, just the Altimeter. The heavy camera would greatly reduce the altitude of the flight. If the parachutes were to deploy too low, there wouldn't be enough time for them to open properly, resulting in a damaging thump on the ground.
I already had many aerial pictures of Fort Indiantown Gap, so no camera. The kit maker says it can handle a C11, but who knows?
The reconfigured recovery system was in place, though not needed for this test flight. I used Nomex and wadding and dog barf, so I didn’t expect any more parachute melting today.
I was glad to see it ignite and lift off just fine, and even more so to see it climb safely away. Initial peak acceleration was 10.8 Gs – pretty good - although it didn’t carry the extra payload weight. It burned for 7/10 seconds and had a very comfortable 5.2 Gs average.
It flew fairly straight despite the stronger winds today. It did only reach a modest speed of 77 mph though. Ejection occurred at 215 feet. It could have done much better because the delay time was only 1.9 seconds. In the next 8/10 seconds it reached its apogee of 237 feet.
After the ejection, I got two clean, untangled and un melted parachutes, and it all looked text-book perfect. It came back at only 7 mph, helped I’m sure by the lacking payload weight. Flight duration was 22.3 seconds, and it landed downwind about 200 feet from the pad. It was a picture-perfect flight, ironically its mission was not to take any pictures this time.
Photos from these rocket flights can be seen in the page Aerial Photography
#C-Thru #NewWayRocketry #Rocket #ModelRocket
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