Harpoon

This is a description of the building of the Harpoon, and eventually flying.

The Quest Harpoon is a sport scale model of the U.S. anti-ship weapon, which can be air-launched, ship-launched or submarine launched. I say sport scale because it generally appears like the real thing, but it is not exact. Changes have to be made to let this rocket fly well without a sophisticated guidance system like the real one employs. Usually this means larger rear fins and smaller forward fins and/or a slightly longer body.  This model has enlarged rear fins. Another important distinction is that this model is made up to look like the two-stage variant that is used for ship and sub launch, but this model only has one stage which does not seperate.  The air-to-surface variant doesn't have a booster rocket stage. The real missile uses a turbojet engine for the upper stage, so it is actually more like a cruise missile.

Here is a picture of the two stage being launched from a ship. The fins/wings are on hinges and pop out after launch.

This second picture shows the upper stage turbojet being used during cruise to the target, the booster not being used since this was launched from aircraft.

Whatever you want to call it, it looks cool, so I am building one. All those fins sticking out of it and the blue/white paint job is what I like, and I like military missiles in general. I was thinking of converting it to a real two-stage rocket, but Quest makes another kit called the Navaho which is a two stage, so I'll leave this one stock.

I begin building this kit by deciding how I want to install an altimeter compartment.  Normally, I just add a length of payload to the top, but that makes the rocket longer and heavier. Also, it is difficult to get parts sized to Quest standards, which use millimeters, while almost every other brand and the parts suppliers use the standard sizes of Estes. I had a lot of trouble finding couplers for Quest, in many cases even Quest doesn't supply them!

So instead I hatched a plan to use the space in the hollow nosecone. Normally that wouldn't be so difficult, but I found out the hard way that most glues, including epoxy and CA glue does not stick to this plastic! I went ahead and made one only to find the CA glue just cracked and seperated right away. So while taking that failure apart, I happened to notice that the hot glue that I used to glue the padding in did stick to the plastic, and stick very well.  So now I use hot glue to glue the critical door hinge piece to the plastic nosecone. I say critical because if that joint fails, it is likely the altimeter will fall to its death and be lost in a giant field of tall grass.

So here is the problem, inserting the altimeter into the nosecone on the left and keeping it secure in there during the high Gs of flight, but have it easily inserted and removed.

I start by cutting the base of the shoulder open, leaving the loop to attach the parachute and shock cord.

I create a hinge part out of scrap plastic (in this case, from a panel of an old busted VCR). The bottom is rounded to the inside curve of the nose cone shoulder, and roughed up a bit to give a good surface for the glue. It's hard to see in this photo, but the inside shoulder of the nose cone is also scuffed up quite a bit.

The plastic hinge is hot-glued in to the side of the nose cone, protruding just a hair beyond the edge. I apply a liberal amount of glue and then some, as a failure here could mean the loss of the payload.  The glue hardens in only a few minutes.

Next, plastic foam padding which was cut to fit is inserted into the empty space, leaving just enough space for the altimeter to be inserted.  Since the attachment loop is in the way, it has to be done in smaller pieces assembled like a puzzle.  Fortunately you don't need to be very precise with the foam, as it is soft enough to squeeze and bend to your wishes.

You could stop there, but I like to form a small box out of cardboard to fit inside the space. It allows the altimeter to slip more easily in and out of the compartment.

With the foam padding inserted, verify that it is a good, snug fit, then dab a few drops of hot glue to the foam to hold it in place.  The cardboard box is now inserted into the space.

A few more dabs of glue holds everything in place.  OK, it doesn't often look very pretty, but at least it is not seen in the finished model.  At least make sure the tiny threads from the hot glue are cleaned up and cut off.

The last step is to rivet a door to the compartment. Before riveting the door in place, make sure that when it is open it completely clears the opening for the altimeter.  When closed, make sure that it covers enough so the altimeter can't be lost with violent shaking.  This may produce an odd-shaped door.  Make sure you have a tight rivet, the door should be difficult to move.  If it is loose, the altimeter may slide out.

Try to file, cut or sand smooth any hard edges on this compartment, or the shock cord or parachute lines may get caught and tangle on any protruding pieces.

Another thing to be aware of when making the door, do not try to make a tight seal. Remember that air must freely flow into and out of the compartment, or the pressure inside may be too high at apogee, resulting in the altimeter will reading too low. Small gaps around the outside are a good thing. If necessary, drill a few small holes in the door.  Remember also to add three or four evenly-spaced vent holes on the body tube, spaced just below the shoulder of the nose cone.

Here is an example of the design change for a Tomahawk Cruise Missile. Notice the size (and weight) difference between the original nose cone, and a payload compartment previously added to the rocket.  The balsa bulkhead and body tube is all extra weight and length that is not needed if you can use the empty space in the nose cone.










With the payload task complete, I proceed to build the rest of the rocket according to the instructions. When building the fins, I break from "tradition".  Notice that the fins are laminated with a thin cardboard covering. This adds strength to the fins, and provides a naturally smooth surface for painting. No time-consuming layers of balsa fillercoat are needed, just a thin bit on the exposed edges.

After laminating, I shaped all of the fins for least wind resistance.  To do this, round the leading edge (top edge) and taper the trailing (bottom) edge.  This elongaged tear-drop shape is the most aerodynamic shape for the fins.  Be sure not to taper the trailing edge too thin, or it will be too flexible, easy to break and will not have an even edge.

Another technique I picked up on fins is to poke small holes in the root edge and the body tube before gluing. Although I haven't yet had an issue with fins popping off even after hundreds of flights in dozens of rockets, the fin to body tube joint can't be too strong.  These small holes allow glue to seep into the wood and cardboard, and provide more gluing surface. More gluing surface = more strength.  When dried, imagine the glue mass with many tiny fingers on it that acts like small rivets.  I say try it, it can't hurt!

With all the fins cut, laminated, shaped and poked, it is time for attaching them to the rocket body. This is the fun part, now that I have built a jig to hold the fins in perfect alignment while gluing them on.  I simply insert the body tube and hold it with bungees, pop the fin in and align the two pieces.  When satisfied, I pull the body tube down a bit and squirt in a line of glue. Then I release the body tube and it presses against the root edge, held fast until the glue dries.  Make sure you excersize patience here, Many rocket builders and kit directions tell you to glue all the fins at once, but it is better to do one fin at a time and let it harden without being disturbed at all.

Work has been slowly progressing on the Harpoon. It naturally slows down with the finishing, partly while waiting for good weather to spray outside, partly to give the many layers of primer and paint to dry, and mostly because all that sanding - necessary for a good finish - is also tedious and hand-numbing.  But slowly the rocket is getting finished...in fact almost done. All I need is one last sanding and a final coat.  After that the painting is done and the decals and final assembly will go quickly.  Here it is so far, I decided against pure white and went with a light gray, but the gray finish turned out much darker than I imagined.  I regret not using white, but at least it will photograph better in flight.


Well I just couldn't handle the gray, so I sanded and repainted gloss white. Much better!  It happened that the gray underneath was well covered by the white, and if it wasn't, I wouldn't mind.

The package shows the nosecone in a different shade of white, sort of off-white. I could have done that, but instead I chose again to make this one stand out a bit with a bright silver finish.

The first coat of silver (Rust-o-leum) was horrible, so I had to sand it off and try again. This time I used an old can of silver that always worked much better and the results were good enough (I believe the problem was the Rust-o-nauseum from underneath).


So here it is in the decal shop.  Starting to look like a real rocket now!

And finally...she's done!

Here are the "formal" portraits:

Of course we can't forget the imposing "big view":

Here's the tail end and motor mount tube, painted silver:

A look at the modified launch lug, set on a standoff. I no longer want the dirty launch lug to rub up along side of the rocket, especially this white one.

Here is a close view showing the static vent ports near the top of the body tube.  The shock cord and parachute will normally be behind these ports.


This is there to allow for the internal air pressure to match the outside air pressure at any altitude. Inside this area (housed in the nose cone just above) is the altimeter, which needs the ambient air pressure to make an altitude reading.



One last look, I wanted you to see the decal gap from the Quest supplied decals. Looks pretty stupid, huh?


OK, so I have it done after about 1-1/2 years since I started (life got in the way). Now it's time for its first test flights (which may take a while depending on the weather's cooperation)!

SPECIFICATIONS

Number of Stages: 1
Overall Length: 20.5" 520.7mm
Body Diameter: T40, 1.575", 40mm
Overall Fin Circular Span: 5.7", 144.76mm
Motor Mount: 18mm x 70mm
Motor Retention: Spring Clip
Recommended Motors: B6-4, C6-5
Stock Weight: 103.6 grams, 3.65 oz.
Altimeter Mod Weight: 3.5g, 0.123 oz.
Nomex Weight: 6g
Overall Weight (Less parachute, altimeter, motor): 114 grams, 3.8 oz.
Recovery Method: Parachute, 14" diameter
Recovery Protection Method: Nomex sheet, 6"x6"
Shock Cord Mount: Kevlar
Altimeter Capable: Yes
Altimeter Payload Volume: apx. 0.45 cubic inches
Date Completed: June 21, 2014

FLIGHT LOG

Has not been flown yet.

USS Prometheus

The USS Prometheus is a low-power kit from Red River Rocketry.  This was my first kit from Red River, and I must say the quality of the parts was excellent all around.  This is a light model, that is recommended to be flown with A, B and C motors.

Most unique for me in this kit was the bright gold Mylar parachute. It was almost unbelievably light - we'll see how it holds up to repeated flights and the occasional 'not enough wadding'.  It should be very visible from the air.  The balsa nosecone, fins, decals, body tube, shock cord, decals and all the other components were first-rate.  My only concern was the string to be used for the parachute, which although it might be strong, was very thin. Thin is more likely to cut through the parachute material, so I substituted it with my normal multi-colored string and made the lengths 1-1/2 the diameter and added a fishing swivel clip.

The "story" behind this is that this is a futuristic cargo transport ship.  They make another model that is a fighter/defender of this ship because of it being attacked by aliens.  My concern: I dont have that model yet, so my Prometheus may be vulnerable to alien attacks.



Construction went well, and this was my first introduction to using Titebond's filler glue for the fillets. It works well, but I should have used a little more to get really smooth results.  Fortunately, the priming and painting went well, with no crazing from the Rustoleum paint this time. It would have been a nightmare to sand out all the hard-to-reach nooks on this model.

As usual, I did add a payload compartment for an altimeter to this model, but instead of retro-fitting a payload, I incorporated it into the initial design, by cutting a three-inch length of the body tube instead of adding to the length of the rocket.  Basically, the only penalty is the weight of the altimeter and padding, and the bulkhead (which was balsa in this particular case).

In addition to the payload section, and parachute risers, other modifications include laminating cardboard to all the fin surfaces before sanding and priming, adding standoffs for the launch lug and hollowing out a portion of the nose cone (for payload space).  A few minor extra decals were added to the design.

There was one other construction technique I tried for the first time on this rocket. This involves punching/poking small holes in the fins and body tube before gluing.  The theory is that more glue will get into these internal spaces and act as small "rivets" of glue to help hold the parts together.  At least this provides more surface area for the glue to make a stronger bond. I find it also helps to "suck up" more of the glue and gives the excess a place to go instead of squeezing out and running.  This will hopefully provide more strength in the fin area, which considering this particular design, it might need it. Here is a look at this technique (as done to a different rocket).

SPECIFICATIONS

Series Number: 31
Number of Stages: 1
Length: 22"
Payload Volume: 2.64 cubic inches
Diameter: 1.325" (BT-55)
Wingspan: unmeasured
Vertical Rudder Height: unmeasured
Engine Pod/Tube Fins: 3
Basic Stock Weight: 76.7 grams
Payload Section Addition Weight (Bulkhead,padding): 5.6 grams
Total Weight with Altimeter: 89.2 grams
Liftoff Weight Range: 108-113.4 grams
Motor Diameter: 18mm
Motor Length: 70mm
Motor Mounting Method: Clip
Recovery Method: Parachute
Parachute: 12" Mylar
Recovery Protection Method: Wadding
Shock Cord Material: Kevlar & Elastic
Nose cone material: Balsa
Fin Material: Balsa, Cardboard Laminated
Completion Date: May 27, 2013

Launcher and Launch Area Technical Support Truck

Here is my LATS Truck, or Launch Area Technical Support Truck.  When the launch area is far away from the parking area, I spend a lot of time walking back-and-forth from the launch area to the car, so to save time and my legs I came up with this contraption.  This allows me to bring all my 'stuff' to the launch area in one trip, and allows me to work on the rockets without having to sit down on the grass and loose small items in the turf.

It is made from a steel utility cart, and has two wooden shelves to hold two toolboxes.  The lower toolbox has tools and various supplies for launching, such as masking tape, binoculars, spare fishing clips, streamers, wadding etc.  The upper toolbox holds plastic storage boxes with the various one-use motors, ignitors and more wadding.

The seperate toolboxes allows me to load them in the car seperately, so loading in the cart is not too heavy. The cart also has hooks to help carry the launch tripod, launch controller, cameras, clipboards and other assorted stuff.  The back of the cart has a fold-out table surface. This surface is framed to prevent small pens, motors, etc from rolling off the edges. It also has a nice, soft cork surface.

In the picture, I have my Alpha and X-Ray out for launching, with a box of wadding, Altimeter Two, masking tape, scotch tape, pliers, sandpaper. This makes it easier to prep rockets while standing, and I don't have to kneel down in the grass and work on often damp or muddy conditions.  It is a real time-saver and knee-saver!

Here are a few closer views of the truck.  This lower tool box has a lot of tools in three drawers and a few spare supplies for rocket launching. It is heavy and should remain in the truck to provide a heavy base for the table when it is extended. I also pack my altimeters, GPS and binoculars in there.

This is the upper toolbox. I use it mostly to store my motors. There are 18 little plastic boxes in seperate compartments in the bottom that hold an assortment of 13, 18 and 24 mm motors.  Above them are four more boxes that hold my most often used motors,  B6-4, C6-5, and D12s.  Of course all boxes are clearly labeled. When not actively flying, this box goes inside and remains in a cool, dry place.  I don't want any of these motors going bad in storage.

You may also notice in this picture that there are hooks on the one side to carry and/or hold camera bags, binoculars, jackets etc.  The large aluminum tube attached to this side holds 4-foot lengths of my three launch rods.  This keeps them safe from being bent and keeps them from taking out an eye or two.

Next I would like to show you my field-deployable rocket rack.  It is designed to hook on to the front of the cart shown above so I can carry all my rockets out to the launch zone with the cart.

I included two features in this design. First, notice that it is "flow-thru", in that reasonable non-hurricane winds will not tip it over and destroy the rockets.  It is also light weight.  All the arms that hold the rockets are padded with cheap pipe insulation.  I used four long bungees (normally used for higher-power shock cords) to hold the rockets tightly but gently to the rack.  While this worked great, I didn't design it to protect the rockets in the rain.  Sure enough, on day one of trying it out, it started sprinkling, so I had to throw a tarp over the whole thing, making it vulnerable to wind.  Oh well, I didn't intend to leave these out in the rain anyways!

Here is the view from behind the rack.  You can see the two posts on hinges that let it lean far back at an angle.  I didn't take any chances with that angle, I made sure it leaned FAR back so it won't tip over from heavy rockets.  You may also see the pipe insulation attached to the rack with staples on the sides of the wood.  You may also see one of the four white bungee cords swung over the back out of the way and not being used at this time.  What is harder to see here is that I used four steel wire sets going from corner-to-corner to keep the front and back frames square. I used stranded steel wire for hanging picture frames.  As it turned out, it was fairly rigid without the wires, but I had them so I put them on anyways.  There are also two strings holding the front and rear sections so they can't be spread too far apart and colapse backwards.

Closeup view showing how the bungees are attached. Simple really. Notice the insulation/padding continues up the wood backing to provide protection to the rocket from the rear also.

 

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This is what my launch system looks like from the inside. It is a fire-resistant box (meant for papers, cash etc.) that houses two 7.2-volt NiCd batteries, so there is a very short path between the power source and the ignitors. This is to minimize the voltage drop across long wires and allow for maximum power being delivered to the igniter.
This box also has a mechanisim to adjust the angle of the launch rod by turning a set of knobs, instead of having to loosen a screw and re-tighten it to tweak the launch angle.
For safety, it has three seperate relays which must all be activated to ignite a motor. This makes it very fail-safe because even if one relay welds itself on and is stuck, the other two will still prevent a ignition.  A long, 25-foot CAT-5 cable connects this box to the control box as shown below.

This controller is mounted on a 3-foot aluminum rod on the left side.  The rod is stuck into the ground and holds this at a comfortable working level.  The large meter on the unit monitors the battery voltage.  To launch, all three red buttons must be pressed and held, and they are spaced apart to require two hands to press all three. Each button enables one of the three relays in the launcher.  Also, the safety key must be inserted, and the arming switch must be on/up.  The small OK LED is used to verify ignitor continuity.






Here we see the launcher deployed in the field.  The entire system is inside the box and remote control.  Both of these parts are held up on a lightweight aluminum structure.  This saves both the back and knees, and in the case of the launch rod, may save an eye as well by being well above eye level for all but the freakishly tall, somebody on stilts or possibly a giraffe.

This closer view of the business end of the launcher shows the mechanisim to hold the rocket up above the blast deflector.  No more burned clothespins or balancing motor casings. It can be adjusted in height and also front-to-back to accomodate nearly any rocket.

The blast deflector is angled to direct the blast to the rear, which somewhat reduces the cloud of smoke obscuring the launch for closeup photography.  Notice too that the ignition wire clips are made using 14 guage solid copper.  This allows them to be bent into position to grasp the igniter wires without pulling them down under the weight of the wires.  These wires are not insulated, so there is no worry about melting insulation.

The only concern here is making sure not to let the two wires short each other or short onto the blast deflector, but that is fairly easy to do.  These clips have held up for dozens and dozens of launches and have not needed replacement yet.  If they do prove to degrade beyond use, I made several sets of spares that can be plugged into the banana jacks in about a second or two.

This launcher is able to use 1/8", 3/16", and 1/4" launch rods. Shown here is the 3/16".

Seen here (above), I added clear white labels to pretty-up the controller a bit, as the previous painted legend was getting a bit ugly.

OK - this is the normal continuity indicator.  It is an LED, so it draws very little current and will absolutely not be enough to heat a igniter.

ARM / SAFE - This basic switch will prevent the igniter from getting current.

CHECK - This button is pressed and held to see if continuity is good. If not pressed, zero current will flow through the igniter, not even a little bit of LED continuity current.  Also, this button must be held down by the left hand to allow ingition, since it completes the ARM current and allows the first of three redundant relays to be energized.

SIREN - This is a second arming circuit that is wired in with the safety key.  When this is pressed (normally at about T-2 seconds), it will energize the second of three redundant relays if the key is inserted.  It is named siren because my intention was to add a mechanical motor/siren to the launcher that will also sound when this second circuit is energized. (I didn't add it yet though, I had it on my workbench but I seemed to have lost it!)

KEY - This key needs to be inserted to allow the second arming circuit to be energized.  When it is removed, the circuit is open and launching can not be done.

LAUNCH BUTTON - This has a silver legend.  Assuming the ARM/CHECK circuit is energized, and the SIREN/KEY circuit is also energized, this button will energize the third of the three relays, completing a circuit from the battery to the igniter.  This is pressed at launch time T-0.  This button is placed on the right side, and is intended to be pressed with the right hand.  The other two buttons are purposefully placed on the left, away from this button, and need to be pressed by the left hand.  This is to prevent a inadvertent bump of  one of these buttons from likely hitting all three buttons.

BAT CHECK - This switch is flipped on to make sure there are no flying bats in the area before launch.  At other times, it switches battery voltage to the center volt meter to indicate the health of the two 7.2 volt batteries in series.  With normally fully charged batteries, this will deflect fully and read 15 volts (ok, 14.4 volts to be exact).  The switch is there to avoid having the meter, which does draw some current, from draining the batteries if left connected for extended periods.

In addition to having the ARM switch on and the KEY inserted and all three red buttons pressed & held, the main launch box which contains the batteries also has its own power on/off switch.  This is to make sure under any circumstance the batteries will not be drained, and is a handy backup swtich when one is at the launcher and about to connect the igniter.  A few times I am unsure and ask myself, "Did I leave the key in and the arm switch on again?"  Instead of having to check, I can just flip this switch to off and be sure I will not ignite the motor as soon as the second clip is attached.

The End.

HD Explorer

The HD Explorer is a new rocket design originally intended to be a camera carrier.  It was started when the Bandit HD needed serious repairs, and no other rocket was available to lift the camera. It is being cobbled together mostly from parts of both the Estes Magician and the Cosmic Explorer.  It shall be a D or E powered rocket, standing just over 30" tall with the camera and altimeter payload section included.

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.

A close view of the forward centering ring and thrust block where the motor presses against during liftoff. The hole allows the ejection charge to pass through.  I will not attempt to make a baffle for this, as in the past it proved to be trouble for these higher power motors. I'm glad I learned this before starting construction.

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.

Now the lower assembly of the rocket has been primed and is ready for final sanding.  The first layer of primer was gray, and this second layer is white which may allow the final paint color to be a bit brighter.  I used a contrasting color on the first primer coat so that it could act as a visual indicator that I have sanded down to the lower layer of primer.

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.

 A year and a half later, I finally completed this rocket. I glued together the lower body tubes, completed touch-up painting and added all the decals.  I attached a Nomex parachute protector and a 5-foot long Kevlar shock cord, having learned the hard way numerous times that elastic springs back and damages the rocket. Although I did create a light wood structure in the payload section to hold the Altimeter 2 and a video camera, I didn't follow through installing a lens opening and the small glass window.  I can always add that later if I need to use this as a camera carrier, if she proves to fly well.  I present to you the finished HD Explorer.

 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

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

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

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

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

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

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

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

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

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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