Since I have started construction, I have changed my strategy to only use this as a back-up camera carrier for two reasons. First, The DEFCON 1 and the C-Thru (also under construction) are also designated as camera carriers, so this need is not critical. Second, computer simulations show that the combined length of this rocket and the heavy weight on the nose will make this rocket over-stable with its large fins, so it is more likely to turn into the wind and fly sideways, making the camera's aim worse. Without the payload weight though it appears that it will fly well. Since the other rocket, the C-Thru is much shorter and has smaller fin area, I expect this to fly better. Additionally the C-Thru has a square payload section, making it much easier to insert an optically clear flat glass.
Still, I want to proceed with the construction of the HD Explorer because I plan on giving it a cool paint scheme (originally intended to make it more visible if it was lost with the camera).
The plan is for a Yellow nose cone, Orange payload, and a Red upper body tube with the lower part white. The fins will have a base of white also, but will have the yellow, orange and red vertical stripes on the tips of three fins. The red portion of the body will continue down on 1/4 of the tube and meet with a single red fin out of the four. This fin will also have yellow and orange stripes on the fin tip. No decals are yet decided except for the number 30 (series number) and perhaps the name "HD Explorer".
The D and E-sized motor mount was constructed first.
The motor mount is shown next to the BT-55 body tube where it will be inserted. The tube has slots for thru-the-wall fins, which provide additional strength to both the fins and the motor mount. I intend to extend the motor tube about 3/8" from the rear.
The balsa fins were cut out, shaped and then laminated with a heavy cardboard stock on both sides using photo mount adhesive. This will make the surface smooth and easy to paint and will add strength to the fins. I will never make fins the "old" way again with multiple coats of balsa fillercoat.
The cardboard is removed from the root edges by sanding so the Titebond III glue has a lot of wood surface to bond to.
Now I prepare the shock cord mount. Since this rocket has a long body tube joined by a coupler, I will use this instead of the motor mount for the shock cord mount. The Kevlar thread is run through a small hole in the coupler, knotted, and the ends are frayed into individual fibers so there will be a lot of gluing surfaces.
The frayed Kevlar is glued flat against the coupler, and a small indent is made on the coupler before inserting into the upper body tube. This is to make sure that the Kevlar doesn't produce a bulge in the outer body tube.
The launch lugs are attached. I like to use two lugs spaced far apart. This allows for a better alignment on the launch rod during liftoff than a single short lug. I also like to space them a bit away from the body tube to reduce the sliding along the body tube and the marks and friction it causes.
After the fins are glued into the body tube slots, I apply a glue fillet along the edges to strengthen the joint. When that is dry, I add a fillet with a lightweight filler to smooth the joint out between the fins and body tube. It not only looks nicer, but it reduces the parasidic drag from right angled surfaces.
When the primer is sanded, the first coat of white paint can be applied. Although I used the same brand of primer and paint, the crazing on the finish shows a lack of compatability. The primer may not have been completely cured, or the first white coat was a little thick. When this rocket was painted however, I painted two different rockets at the same time, with the same primer and the same paint. The other rocket came out beautiful though, I don't know why this happened here. Either way, this requires sanding off all the cracks and making another attempt.
It's as strange and predictable as Google's blog editing screen. Sometimes it works, other times you can't add text NEXT to the pictures. Very frustrating!
I don't know why, but this time the coat of white paint has worked well. Here I am satisfied with the fillets on the fins (it's the first time I have used filler for the fillets, and it looks much better than the irregular glue fillets I generally leave visible). This body will still need masking and spray painting with yellow, orange and red on the fins.
The other sections of the rocket have been primed and sanded, but still need final paint. Since I left each section seperate, I don't have to mask to apply the right colors. From the top, the nose cone will be yellow, the payload section orange, and below that the upper portion of the body tube will be painted red.
I am trying a new method to secure the altimeter in the payload section. Instead of plastic foam padding, I am making a lightweight wood structure to hold securely both this and a video camera. I hope that this will be both lighter and stronger.
I had an option when I was designing this model to add a small forward fin set to compensate for the over-stable condition. It has been optomized for the heavier weight of an F engine, but will make the model less stable with even an E or D motor. These fins will compensate for the extra weight in the payload bay, but it should also fly well without the additional noseweight.
The large fin area in the back of the rocket produces too much of a restoring force which turns the rocket towards the apparent wind, so these small fins ahead of the center of gravity will do the opposite, and nullify some of the restoring force generated by the large rear fins. I hope to make two identical payload sections, so I can fly this model both ways and see if this theory actually works in the real world. I will be able to compare the performance of this rocket both with and without the forward fins. These fins were placed far below the camera's aperture and tapered away to prevent them from being in the picture frame. If I could have moved them further up and away from the center of gravity, they could have been smaller and would have generated less aerodynamic drag.
These forward fins were cut, laminated, and attached to the payload section in the same way as the main fins. So now all the pieces of this rocket are ready for finishing.
Here is a picture of the nose cone (yellow) and the payload section (orange) sitting on top of the HD Explorer. This section has been primed and I started painting it, but stopped when I found the color (flourescent orange) was not to my liking, so I will finish it with a 'normal' orange paint.
As of this day, Nov 21, 2012, this is as far as I got. The weather turned cold outside and it is not a good idea to do spray painting in the cold air. I will need to wait for a warmer day to finish this rocket.
Spring, 2013: I get the chance to spray paint more. Most of the rocket painting is going well, but when I attempt to add some detail to the fins, the orange paint (Rustoleum: same brand as the primer, and the white base coat) is giving me crazing trouble again. I wish I didn't buy so much of that paint! Here is the result of painting a vertical orange stripe over the white basecoat. Apparently, I need to let the paint cure for days...weeks even, before another coat can be added. At this rate, the rocket will be finished in November!
As usual, I sanded down the orange scum and tried again with better results. I am starting to get excited about the project, as it is mostly complete and beginning to look pretty sharp.
The red paint is next. I intended to use the red paint not only as another color accent, but I will make a roll pattern (an identifying mark used to see and analyze the rolling motion of the rocket upon liftoff). One single fin and 1/4 of the body will be painted red, so I had to mask off all of the other fins and the orange & yellow stripes of the fourth fin to be painted red. Fortunately this went well. I had similar good results with my other rocket the C-Thru which was painted white then red.
Here is the end result of the one red fin. Seperately, I will mask and paint a red stripe on the other three fins. I will then go back and touch-up the orange then the yellow edges of the paint.
Of course I did have an "issue" with the red coat as shown just above/left. As I always heard, colors come out brighter when applied to a white base. I didn't think of that when I painted the upper section of the booster solid red. So when I connect the two pieces, instead of looking like an exact match, there is a noticeable color difference. Both shades of the red color is fine for me, but not at the same time. The only solution is to repaint the upper section white and then red again. I haven't decided if it is worth the time and weight penalty yet.
So here is the assembled rocket so far. Yes, it does look almost a bit too colorful and kind of like a kid's toy, but that is actually the original intent: To make sure it is visible in the air or the ground as it will contain several hundred dollars of electronics. It will look better when I get some decals on it.
This may be a little late in comming but I have produced a digital rendering of what the HD Explorer should look like. The blue dot shows the aproximate center of gravity, the red dot shows the aproximate center of pressure.
OK, this is a weird optical illusion:
Look at the Estes logo above, it is reasonably well placed,
don't you agree?
So now look at the bottom picture.
Same logo (there is only one on the rocket).
Does it still look striaght to you?
I love this view of the 24mm motor opening, looks powerful.
Truthfully, I like the effort and the design seems nice enough. It indeed does meet the original requirement of being very visible, but I think it came out a little funny, perhaps a bit too cluttered looking, maybe the orange payload should have been red, yellow or white.
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SPECIFICATIONS
Stages: 1
Overall Length: 30.6"
Main Body Tube Length: 18"
Nosecone Length: 5.05"
Payload Internal Length: 4.5"
Payload Internal Diameter: 1.28"
Payload Volume: 5.79 cubic inches
Diameter: 1.325" (BT-55)
Flying weight with altimeter: 141.7 grams
Motor Diameter: 24mm
Motor Mount: Spring clip
Typical Parachute: 20" dia. returns at 8 mph
Recovery Protection: Nomex cloth 6"x6"
Shock Cord Mount: Kevlar
Payload: Space for mini video camera
Altimeter Capable: Yes
Fin Material: Cardboard Laminated Balsa
Unique Features: 4 fins span 4.375", 4 forward fins span .875"
Launch Lug size: 1/8"
Glue: Titebond III
Paint: Rustoleum PT2X
Motors Used: C11-3, D12-5, E9-6, E12-6, E15-7W, E30-7, F32-6
Designer: Me, Rich DeAngelis
Started: August 2012
Completion: Oct 22, 2013
2019, May 25: Indiantown Gap, PA, 5-10 mph wind, 70deg.F
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| As we look at the next 4 photos in this series, we can see that this may be a good camera carrier rocket because it did not rotate on liftoff. There is one red-painted fin which can't be seen from the camera's angle at launch. In the next three photos on the liftoff, that single red fin never becomes visible - it hasn't rotated even 90 degrees. |
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D12-5: The first ever flight of my new rocket was to happen today. Yes, it was
later in the day and the wind picked up a bit, but since I purposely considered
winds when making this design, I thought I’d test it with a trial-by-fire. The
forward fins should keep it from being over-stable, and not turn too much into
the wind.
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Upon ignition, it accelerated well with a 10.3G boost, as expected of a D12
Upon ignition, it accelerated well with a 10.3G boost, as expected of a D12
motor. The burn was 1.8 seconds as also expected, giving the rocket an average
acceleration of 3.2 Gs. This flew up without turning too much. It reached a top
speed of 123 mph.
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The delay was longer than most at 5.8 seconds. It only coasted for 4.8 seconds
The delay was longer than most at 5.8 seconds. It only coasted for 4.8 seconds
to an apogee of 595 feet, while the last second of delay it dropped 21 feet where
the ejection fired. At 574 feet I got a good parachute, allowing the rocket to
return at 10 mph. It landed about 300 feet to the east, not downwind to the
north as expected. This was a 44.8 second flight, and all 44 seconds of the
flight was a success.
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This design was now shown to be at least workable.
My rough prediction was 750 feet, so for an untested design that wasn’t terribly
My rough prediction was 750 feet, so for an untested design that wasn’t terribly
far off. Since this model can take an E or even an F composite, 595 feet is the
low end of its performance range. It has at least verified that it should fly
well enough with a C11 motor.
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D12-5: I sent the HD Explorer up again with the same motor, which could prove or
dis-prove the validity of the previous readings.
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| On this second flight, the red fin is visible on the right side. Note that this fin remains visible in the next three photos, indicating that the rocket has not rolled on liftoff. That's why one fin is often painted a different color, for camera analysis of the flight. It's not for artistic purposes - or at least that wasn't where the idea came from. |
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This second ever flight took off with a similar 9.9 Gs and burned for 1.8 seconds
This second ever flight took off with a similar 9.9 Gs and burned for 1.8 seconds
also. The average acceleration was identical at 3.2 Gs. Remarkably, it also
reached a top speed of exactly 123 mph.
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This motor had less of a delay, only 4.6 seconds long. As a result, it ejected
This motor had less of a delay, only 4.6 seconds long. As a result, it ejected
at 597 feet. It apparently wasn’t travelling to fast upwards at that point,
because in the next 8/10 second it only gained another 8 feet to reach an apogee
of 605 feet.
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With a good parachute (home-made by the way), it may have caught some thermal
With a good parachute (home-made by the way), it may have caught some thermal
lift, because the average descent was only 6 mph, and it drifted far down wind
into the next field. It barely missed a wide row of trees and a swampy area, as
it landed only 10 or 15 feet from the tree line in the adjacent dry, flat, and
short cut field. This flight lasted for 69.4 seconds. Over a minute! Nice.
The wind, the launch location decided by the club, and the choice of high power
The wind, the launch location decided by the club, and the choice of high power
nearly combined to produce a disaster flight, having my first original design to
hang in a high tree that may not have ever been seen, or a wet landing in the
swampy, watery area nearby.
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I speak with authority on the difficulty of the swampy area. As I was walking
I speak with authority on the difficulty of the swampy area. As I was walking
thru to search the other side of the tree line, I stepped in progressively more
muddy soil and grasses, only to find myself in the next step sinking deep enough
to pour mud and water into my boots. I began to worry about snakes and other
biting critters, then refocused on my search.
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| A nice pair of Land's End hiking boots with cakes of mud on the inside. |
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| A pair of socks that used to be white, but may never again be called white. |
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I think I got lucky with these two flights, unlike the previously destroyed X-Ray
I think I got lucky with these two flights, unlike the previously destroyed X-Ray
flight. I was also lucky that I had another pair of waterproof shoes in the car.
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2019, Sept 21: Halifax PA, 5 mph wind, 75deg.F
C11-3: This promised to be a fine day for launching. Light winds, good temperatures, clear sky, large field, dry earth and low cut grass all combined to make this an ideal field. Even with the predicted light winds, I needed a low flight to boost my confidence, so I chose to do the low-power test for the newly minted HD Explorer.
Having never flow with a C11 motor, and in fact no model of this exact type has flown with a C11, I could only predict 275 feet apogee for this flight.
The small-ish motor lit on que, and pushed the rocket off the pad with a high 13.4 Gs, more than the D12s. The average acceleration was also higher than a D12, at 5.6Gs, expected because of the lighter propellant load and the short burn time of 0.6 seconds. This was enough impulse though to get the HD up to 78 mph.
This was followed by a 2.1 second delay, and upon reaching an altitude of 219 feet, the ejection charge fired early, slowing the rocket for the next 1.2 seconds. With a total coast to apogee time of 3.3 seconds and another 33 feet gained, it peaked at 252 feet above ground.
By that time the 21” parachute was opened, and the rocket began a descent at a leisurely 7 mph. After a 22 second flight it touched down in the grass safe and sound. The low altitude combined with the light winds and large field allowed me to use a big parachute. Even then, it landed only about 100 feet away.
Being the lowest power flight, of course the altitude, speed, coasting time, and flight duration were the lowest. Compared with the recovery efforts of previous flights though, this may have been the best.
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D12-7: Having flown twice with a D12-5, I knew what to expect. The 5 second delay was shown to be good enough, but since I only had a 7, I had no choice. As it happened I had nothing to worry about.
The flight began with a strong launch creating 11.5 Gs. The burn of 1.8 seconds of power produced 3 Gs of acceleration on average, which was the lowest of all the HD flights.
After reaching a top speed of 118 mph, it coasted for a full 5 seconds, made apogee at 592 feet, then fell 30 feet before ejection at 562 feet above the earth. The speed and apogee were just slightly below the previous D12 flights, while the average acceleration was lowest.
The ejection of this D12-7 was close at 6.2 seconds of delay. Everything was nominal. I got a good parachute which let this rocket return at 9mph, and it landed safely about 250 feet downwind.
I know this rocket is good with C and D power, now I only need to see it with E power, and maybe someday try to fly it as initially intended – with a camera.
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