Apogee COMPONENTS MX-774B Hiroc Kit Instruction Manual

June 1, 2024
ApoGEE COMPONENTS

Apogee COMPONENTS MX-774B Hiroc Kit

Apogee-COMPONENTS-MX-774B-Hiroc-Kit-PRODCUT-removebg-
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Specifications

  • Model: MX-774B Hiroc
  • Skill Level: 5 (Advanced Skills Needed)
  • Manufactured in: USA
  • Manufacturer: Apogee Components Inc.
  • Website: www.ApogeeRockets.com

Parts List

Item # Item Name Qty
10110 AT-29/13 1

Required Tools

  • Hobby knife with sharp blades
  • Razor saw
  • Ruler
  • Pencil
  • Wood glue
  • Medium and thin CyA adhesive (super glue)
  • 15-minute epoxy and thickened epoxy
  • Masking tape
  • Wood filler
  • Sanding sealer
  • Modeling filler
  • Coarse, medium, and fine sandpaper (80 grit, 180 grit and 320 grit)
  • Sanding block (such as the Apogee Sanding Tee P/N 02100)

Optional Tools / Materials / Finishing Supplies:

  • Filled Epoxy (or thickened epoxy)
  • Paper Towels
  • Spray Paint (Gray Primer, White, and Black)
  • Detail Paint (Steel Metallic, Aluminum Metallic, Rust Red, Bright Red)
  • Decal Setting Solution
  • Satin Clear Coat
  • Modeling Paint
  • Paint Brushes
  • 1/4” Wood Dowel
Item # Item Name Qty
10110 AT-29/13” 1
10230 AT-18/0.8”x4 (Hiroc Dummy Nozzles) 1
10258 AT-74/14.5” 3” Thin Wall (Hiroc) LC 1
13061 Rail Button Airframe Type 2
13065 6-32 x 3/8 Flat Phillips Machine Screw (for rail buttons) 2
13066 Weld Nut for 1010 Rail Button 2
13080 #8-32 Nut 1
13085 #8-32 x 4” Full Thread Stud 1
13328 CR-29 (Thin-Wall) / 74 (Thin-Wall) 1
13378 CR-29 (Thick-Wall) / 38 1
14000 #8 Flat Washer 1
15500 Hiroc Ring Sheet (Cardstock) 1
15501 Hiroc Fin Alignment Guide 1
15738 Hiroc Fin Core Sheet (Basswood) 2
15739 Hiroc Fin Facing Sheet (Balsa Wood) 4
19490 Apogee PNC-74mm (3-inch) 1
19491 Hiroc Boat Tail LC 1
29094 30” Printed Nylon Parachute 1
29372 9×9 Apogee Parachute Protector 1
29528 300# Kevlar 10 ft.

31284-

31288

| Hiroc Instructions| 1
37021| Hiroc Detail Sheet A| 1
37022| Hiroc Detail Sheet B| 1
39105| Hiroc Face Card| 1
41124| Hiroc Decal Sheet (waterslide)| 1

Skill Level 5

Advanced Skills Needed
The MX-774B Hiroc is a lesser-known test vehicle that introduced many useful features to early rocket designs. This kit is a large, 1/10 scale, mid-powered rocket that stands just over 40 inches tall with a 3-inch diameter. Construction is of traditional plastic for the nose cone and boattail, along with Apogee’s high-quality paper tubes and fins which are constructed from a combination of balsa and basswood. Cardstock and balsa form the remainder of the surface detail. Add some paint and the included water-slide decals, and the result is an accurate representation of a truly revolutionary early rocket design.

History of the MX-774B Hiroc
In October of 1945, the Army Air Force’s Air Technical Service Command requested industry proposals for designs of long-range intercontinental missiles with a range of at least 5,800 mi. The following January, the Consolidated-Vultee Aircraft Corp. (Convair) submitted the proposal which became the MX-774B project. Within the overall project, the “B” variant (the only variant built) was the smaller of two rocket designs while the “A” variant was to be a cruise missile. Originally funded for ten flights of the “B” variant before the much larger “C” variant would be built, the project was later defunded leading to only three flights of the Hiroc (High-altitude Rocket) being made in the life of the project. These three flights were made at the White Sands Proving Ground in 1948 and each suffered from partial failures such as early engine shutdown and failure to deploy the parachute.

For such an insignificant seeming project, however, the Hiroc represented the beginning of a rocketry dynasty that went on to be extremely successful. Looking very much like a stretched V-2 rocket (though, in truth, it
was substantially smaller), there were several revolutionary features present in the design. First and foremost, the Hiroc was the first vehicle to use thrust vectoring for directional control. With the ability to move the four- engine chambers independently, control in yaw, pitch, and roll was possible. Additionally, the Hiroc used tanks integral to the structure of the airframe. This design was further evolved into the Hiroc’s eventual successor at Convair, the SM-65 Atlas ICBM which took the concept to its extreme with the structural balloon tank. Following on from the earlier design of the MX-774B Hiroc, the Atlas became the first ICBM to see operation in the United States; the Atlas was not the absolute first ICBM as it was beaten by the Soviet R-7 which launched Sputnik 1 into orbit on October 4, 1957.

As the ultimate source of many of the powerful ideas that led to the Atlas ICBM, the Hiroc has an important place in the lineage of the Mercury Atlas and the United States’ entry into manned space flight. As such, the MX-774B project – despite its minimal historical footprint – was a highly valuable addition to early exploration in rocketry.

Notes on Scale Accuracy:
As a very early rocket that was produced and launched in only small numbers, the Hiroc has limited scale data readily available. A reasonable effort has been made to make the rocket as accurate as possible given the data that has been obtainable. The result is that the overall dimensions of the rocket should be quite accurate. The surface details and decals, on the other hand, are approximations to a much greater extent. For a competition rocket, additional work to improve accuracy would be suggested.

With regards to paint colors, the colors specified are taken from historic photographs and descriptions. As such the recommended paints are currently a “best guess” and no exact color references are given. Given the photos we have found, however, we believe the recommendations to be quite accurate.

Apogee-COMPONENTS-MX-774B-Hiroc-Kit-FIG-1

Assembly Installation Instruction

Assembly Steps
The MX-774B Hiroc is designed with many scale details which can make the construction more involved. Steps such as the addition of raised panels are optional if the goal is simply to build a sport-scale flying model. Optional steps are marked as bold. Some other details are more difficult to build around so those steps are not deemed optional, but the skilled builder could easily work around those as well – should they choose to do so.

Fin Assembly

  1. Remove the four basswood fin cores (from sheets P/N 15738) as well as the sixteen balsa-facing pieces (from sheets P/N 15739). The first decision to be made on the build is if two of the fins will include
    S-Band antenna fairings (which is scale) or if all four fins will. The advantage of building with antennas on all four fins is that the rocket will stand upright when completed; when only equipped with two antennas, the rocket will require a display stand. Optional: if building scale (with two S-Band antenna fairings) use a sharp hobby knife to cut the small fairing nibs from the basswood cores of two fins to create flat aft edges.

  2. Install the balsa-facing pieces beginning with one of the aft-facing parts. Apply medium CyA adhesive to the bottom of the facing piece and put it into place flush with the edge of a fin core and with the cutout aligned with the slight nib on the core. For best adhesion of the facing parts, a thin uniform layer of adhesive is best.

  3. Install the forward-facing piece by again applying medium CyA adhesive to the bottom of the facing piece and apply the facing to the core, flush with the outer edge of the core. If there is a slight gap between the facing sections, that is okay as it can be filled later when the final surface of the fin is filled and sealed. Repeat steps 2 and 3 for all the facing sections on both sides of all four fins.

  4. Optional: if building scale fins (with only two S-Band antenna fairings) cut four of the facing filler sections from the laser cut facing sheets (P/N 15739) and glue them into place on the two fin blanks without antenna fairing nibs (that were removed in step 1) using medium CyA adhesive to secure the balsa in place. Any gap will be filled later.

  5. Apply a bead of thin CyA adhesive along the edges of the fins between the facing balsa and the basswood cores to prevent chipping of the edges while the fins are being shaped. Allow the CyA adhesive to set entirely before continuing to shape the fin blanks you have assembled.

  6. The first step of shaping the fins is to taper them from root to tip. Using a coarse sandpaper (80 grit), sand a linear taper into the fin blanks from the full thickness at the root, down to 5/16” (8mm) along the tip. Be careful to sand the fins evenly on either side of the core and sand so that the final surface is flat. Taper all four of the blanks similarly.

  7. Once the blanks have the initial taper sanded into them, the trailing edge should be tapered. Use a coarse sandpaper (80 grit) to taper the aft section of the fins down from the centerline of the fins (marked by the joint between the forward and aft facing pieces) down to the trailing edge. Take care to avoid damaging the nib that sticks out past the trailing edge (on the two or four fins that have it) when sanding down flush with the fin core. Repeat on both sides of all four fins.

  8. Use a medium grit (180 grit) sandpaper to shape the fins into smooth airfoils. Only a small amount of material needs to be removed from the middle of the fins as the two tapering steps have removed the majority. Pay special attention to the leading edge and form a smooth uniform curve on all four fins.

  9. Remove the S-Band antenna fairing sides from the basswood sheets (P/N 15738). One at a time, and the pieces so that when they are installed next to the nib on the fins, the final form will be smooth like a bullet and will also meld smoothly into the fin surface. Once a fairing side is shaped, install it with medium CyA adhesive. Repeat for all eight fairing pieces (or four, if building with the scale two S-Band antennas).

  10. Remove the control tab hinge details from the cardstock sheet (P/N 15500) and glue into the slots on the fins using medium CyA. The flared section of the hinge detail goes toward the aft end of the fin while the forward section will roughly parallel the sanded surface of the fin.

  11. Use a wood filler to smooth any gaps, wood grain, or damage on the fins and allow it to dry. Use fine sandpaper (320 grit) to smooth the surface. Repeat as necessary to ensure that any imperfections have been repaired.

  12. Optional: Cut out the fin root surface details from the printed cardstock sheet A (P/N 37021) and wood glue into place at the aft corner of the root edge on either side of each fin. Allow the fins to dry entirely before sealing the fins.

  13. Apply multiple coats of wood sealer to the fins to hide all the wood grain. This process is very similar to applying the wood filler. Simply apply a coat of sealer and allow it to dry. Once it has dried, sand the sealer with fine sandpaper (320 grit) until uniformly flattened and reapply a fresh coat if the grain has not been filled yet. Once the fins are smooth, set them aside for later assembly. Rail Button Mounting

  14. The rail buttons are mounted to the boat tail and main body tube. To install the forward weld nut, apply some medium CyA adhesive to the upper surface of the weld nut and press it into place so that it sticks out of the main body tube through the small hole. Use a piece of masking tape to hold the weld nut in place while the adhesive sets.

  15. Cut off the pointed end of the laser-cut boat tail (which generally comes in the kit looking like a complete nose cone) and remove any plastic remaining in the slots using a sharp hobby knife. Sand the laser-cut end smoothly using fine (320 grit) sandpaper.

  16. Using a razor saw, cut the loop off of the shoulder end of the laser-cut boat tail. Separate the piece at the molded grove just behind the loop.

  17. Remove the round spacer from one of the basswood fin core sheets (P/N 15738) and use the laser-cut boat tail to sand the spacer so that it conforms to the shape of the surface. Use medium sandpaper (180 grit) held against the surface to sand a small conformal undercut on one side of the standoff. When sanded, the aft side of the standoff should be the full 3/32” (2.4mm) height of the wood while the opposite side should be about half that depth (3/64”, 1.2mm). A perfect match is not necessary as the joint can be easily filled during finishing.

  18. Use medium CyA to glue the standoff into a position aligned with the rail buttonhole in the boat tail. The taller side of the standoff should face toward the small end of the boat tail to ensure that the rail button is as close to square to the rocket’s axis as possible.

  19. Install the second weld nut into the boat tail by applying medium CyA adhesive to the upper surface and installing the weld nut through both the hole and spacer. Push the weld nut firmly against the interior of the boat tail. Use a small piece of masking tape to secure the weld nut as the adhesive sets.
    Motor Mount Assembly

  20. Remove the two parts of the aft centering ring (rings A and B) from the laser cut heavy cardstock sheet (P/N 15500). Glue the two sections together using a thin layer of wood glue and align the central hole as well as the motor retainer hole.

  21. Mark the motor mount tube at 1/2” (13mm) and 5-1/8” (130mm) from the aft end of the tube. Also mark the tube 1/2” (13mm) from the forward end of the tube.

  22. Wood glue the aft ring just forward of the 1/2” marking on the motor mount tube being careful to ensure the ring is at right angles to the tube on all sides. Allow the glue to dry so that the ring is securely bonded to the tube before continuing.

  23.  Test fit the aft ring in the boat tail by installing the motor mount from the front. Because of variation in the blow molding process the thickness of the boat tail varies slightly; use coarse sandpaper (80 grit) to sand the outer edge of the aft ring so that the ring will sit just behind the aft edge of the fin slots.

  24. Separate the simulated nozzles from the laser cut 18mm tube using a sharp hobby knife, taking care to not distort the shapes too much. Discard the waste backing and ensure that any remnants of tabs are cleaned from the nozzle edges.

  25. Remove the motor mount tube from the boat tail to provide access to install the simulated nozzles. Glue the individual simulated nozzles in place with wood glue applied around the edge of the inset in the aft ring and up the side of the motor mount tube. Use a cotton swab to clean up any excess glue to avoid the need to sand it off later.

  26. Remove the rectangular cardstock spacer from the heavy cardstock sheet (P/N 15500) and wood glue it into place just forward of the aft centering ring and in line with the small hole.

  27. Remove the middle ring from the heavy cardstock sheet (P/N 15500) and using wood glue install it forward of the marking which was made 5-1/8” from the aft end of the motor mount tube.

  28. Using coarse (80 grit) sandpaper, sand the dotted section off of the large plywood centering ring (P/N 13328). This will allow the ring to slide past the rail button inside the tube in Step 36.

  29. Wood glue the small centering ring (CR-29/38, P/N 13378) forward of the mark at the forward end of the tube. Be aware that the fit of this ring will be loose. This is expected. This ring does not provide alignment but rather, it provides strength to both the shock cord attachment as well as the forward centering ring, so ensure that a continuous film of glue is present between the tube and the ring. Continue to complete the next couple of steps while the glue is still wet.

  30. Tie the shock cord around the motor mount tube just aft of the small ring. Use a slip knot to allow the shock cord to be pulled tight around the tube.

  31. Route the shock cord through the center of the plywood centering ring (P/N 13328) and wood glue the ring into place against the support ring installed in the last step. Rotate the ring so that the flat created in step 28 is roughly in line with the motor tainer hole. Pull the shock cord tight against the support ring then apply fillets to the joints and over the shock cord loop. Allow all the glue on the motor mount to dry before continuing.

  32. Apply a small amount of epoxy adhesive to the surface of the cardstock spacer then insert the threaded rod into the motor mount with 1- 3/16” (30mm) of the rod extending beyond the motor mount tube.

  33. Soak the edges of the nozzles with thin CyA adhesive to stiffen and protect them.

  34. Fill the spiral grooves in the exterior of the nozzles with a modeling filler and once dry, sand them smooth.
    Assembly of Subassemblies

  35. Ensure that the fins all pass through the slots in the boat tail smoothly and that the root edge of the fins are not lifted by glue blobs. Clean the slots and fin root so that the fins sit tightly against the surface before continuing.

  36. Apply a small amount of epoxy inside the boat tail where the forward and middle centering rings will sit -one bead to the forward and aft of the fin slots. Slide the motor mount assembly into the boat tail and align the simulated nozzles so that they are in line with the fin slots. Then slide the assembly into the main body tube (WITHOUT GLUE) to ensure that the motor mount is centrally aligned, using the flat on the forward centering ring to clear the weld nut in the main body tube more easily. Allow the epoxy to set before continuing.

  37. For installation of the fins, a long-cure epoxy is preferred to allow for more time to get everything fully aligned. If only a 15 minute epoxy is available, consider installing two fins at a time (on opposite sides of the tube). Apply a small amount of epoxy to the bottom of each fin tab as well as the root edge of the fin, and insert the tab through the slots so that the root of the fin is flush against the boat tail. There will be gaps between the balsa facing of the fin and the boat tail where the fins are thickest, but the forward and aft ends of the fin should be tight against the boat tail. Once all four fins are installed, use the included cardboard fin alignment jig (P/N 15501) to ensure that the fins are correctly aligned. Use masking tape to hold the fins tight against the boat tail. Optional: If the scale option of two antennas was chosen, the two fins with antennas should be installed opposite each other with one of them installed in line with the alignment mark cut into the forward end of the boat tail.

  38. Once the fins are installed, remove the alignment jig and apply epoxy fillets around the roots of all the fins. To make the creation of uniform fillets easier, and also reduce the mess, apply masking tape (blue painters tape or Tamiya masking tape) approximately 1/8” (3 mm) from the joint on both the boat tail and around the base of each fin. Use a filled (thickened) epoxy to prevent the fillets from flowing out of place then use a 1/4” dowel or finger tip (while wearing gloves to avoid epoxy allergies!) to apply the epoxy and smooth the fillet. Allow the fillets to partially harden so that the epoxy is still flexible and slightly tacky. Carefully remove any tape as removal at this stage is easier than when the fillets are fully hardened.

  39. Pull the main body tube off of the fin can assembly then pass the shock cord through the motor mount tube and out the back of the rocket.

  40. Apply epoxy inside the main body tube approximately 1” and 4-3/4” (25 mm and 120 mm) from the back edge using a dowel – the rail button is installed closer to the back edge of the tube. Slide the fin can assembly into the back end of the main tube and align the two short alignment marks (at the edge of the boat tail and engraved at the edge of the body tube). This will also align the rail buttons. Press the fin can all the way into the main body tube to close the joint and ensure that a solid fillet has formed on the forward side of the plywood centering ring. If no fillet is visible from the top of the tube, apply a fillet to the joint using a dowel.

  41. Apply modeling filler to the boat tail/body tube joint as well as the spiral groove on the main body tube. Once dry, sand the filler to achieve a smooth surface.

  42. Optional: Cut the nose cone extension wrap out of the printed thin cardstock sheet A (P/N 37021) please note, a second wrap is provided, just in case. This extension can either be wrapped by hand or it can be wrapped with the assistance of a 3D printed jig (NOT INCLUDED, file available HERE). Pre-curve the wrap by pulling it over the edge of a table or forming it around a small dowel.
    Scan QR Code for Link to Instructional VideoApogee-COMPONENTS-MX-774B-Hiroc-
Kit-FIG-45
    www.apogeerockets.com/Advanced_Construction_videos/Rocketry_Video_405

  43. Form the wrap into the correct shape then apply wood glue to the tab (marked “Overlap”) and tape the extension together. Take care to form the extension with a sharp point. Attach the extension to the nose cone with epoxy. First fill the tip of the extension with epoxy and then apply a thin layer to the remainder of the interior of the extension, sliding the extension onto the nose cone and holding it in place with masking tape while the epoxy hardens.

  44. Once the epoxy has cured, remove any tape then fill (using a modeling filler) and sand smooth the length-wise step in the extension using fine (320 grit) sandpaper. Do not fill the step at the base of the extension as it represents a panel joint.

  45. Round one end of each half-round piece of balsa using medium sandpaper (180 grit) to represent the forward end of the cable races on either side of the rocket. The front end should be roughly the shape of an ellipsoid. The engraving on the main body tube can be used as a reference for the shape of the cable race.

  46. Once the forward end has been shaped, cut the balsa half-rounds to a length of 14-3/4” (375 mm) and shape the aft end of the balsa so that it fits nicely around the front edge of the two fins that are inline with the engraved mounting locations.

  47. Once they fit accurately around the fin, use medium CyA adhesive to glue the cable races into place within the etched lines on the main body tube, from the fin forward along the boat tail and main body tube. Take care to keep the cable race secure against the curved boat tail section.

  48. Optional: The tank wraps are purely aesthetic and so can be skipped if desired, but they are certainly worth the effort as the final product is substantially more interesting and accurate. The wraps A & B should be cut out of the thin cardstock sheet B
    (P/N 37022) using a sharp hobby knife and the hole (in wrap A) should be lightly sanded using fine (320 grit) sandpaper to create a smooth edge. Wrap A is applied on the opposite side of the rocket from the rail buttons. Dry test the fit of the wrap. It should conform tightly to the body tube and extend to the balsa cable races. The wraps are marked slightly oversized and can simply be trimmed down to fit. To apply the wraps, spread a thin layer of wood glue on the printed side of the wrap and position the wrap between the engraved lines on the main body tube. Apply wrap A with the hole toward the back of the rocket. Repeat for the second wrap (wrap B, on the side of the rail buttons) and allow the glue to dry.

  49. Repeat the previous step for the outer wraps (C and D) by cutting them out of cardstock sheet A (P/N 37021), dry fitting, and trimming for a proper fit. Apply wood glue to the printed surface of the wrap and install it. Wrap C (with the large circle cut out of it) should be applied flush with the aft edge of wrap A with the holes concentric, while wrap D (the solid rectangle) should be applied flush to the aft edge of wrap B.

  50. Route the shock cord back through the motor mount tube. Cut a slot in the parachute protector at the buttonhole location and pull the shock cord through the slot. Slide the parachute protector toward the rocket to make room for the nose cone and parachute.

  51. Tie the shock cord onto the nose cone loop, securing the tails of the knot with a small piece of masking tape.

  52. Attach the parachute by collecting the center of the parachute’s shroud lines. Pass the combined lines through the loop on the nose cone, and pull the parachute back through the loop in the lines, pulling the knot tight. Finishing of the Hiroc

  53. Fill any imperfections in the rocket with a modeling filler, allow to dry, and lightly sand the entire rocket with fine sandpaper (320 grit) then apply a thick coat of sandable primer to the entire rocket. This is particularly important to seal the more porous materials such as the balsa and the cardstock details. Sand the primer coat to make the surface smooth but avoid rounding the edges of the cardstock details. Apply modeling filler to fill any remaining imperfections on the surface of the rocket. Allow the filler to dry and sand the surface smoothly (again using 320 grit sandpaper). Finally, apply a thin, uniform, coat of primer to the entirety of the rocket to provide a solid base for the paint. If the next (Optional) step of preshading the rocket is going to be completed, it is suggested to do this final coat of primer using a medium gray primer to provide contrast to the preshading.

  54. Optional: Apply shading to the rocket to add detail to the final paint job. Suitable preshading includes painting the wraps around the center section with a white primer. Additionally, apply black (or dark brown) paint to any panel lines that should be highlighted. It is recommended that the panel lines be highlighted in acrylic paint if the base paint is going to be enamel (such as most rattle can paint) to minimize it being dissolved by the base coat. Optimal preshading will have a sharp, dark, edge at the panel line, and fade toward the back over a length of 1/4” – 1/2” (6mm – 12mm). In any case, it is important to run compatibility tests on the paints to ensure that the top paint will not dissolve the preshading paint or cause it to bubble.

  55. Apply the white base coat to the rocket, ensuring a uniform coat but being careful to not entirely cover any pre-shading that was done in the last step. The result (with the optimal two-tone primer) should be a subtle two-tone white with darkened areas at the panel lines. Allow the base coat to dry entirely before continuing to detail colors.

  56. Mask the rocket for the roll pattern and the black forward ring (on the nose cone). Take care that the fin tab areas are masked so that the rust red tab color can be applied to the white base coat rather than having to be placed over the black. Fin tab templates are included on cardstock sheet A (P/N 37021) to properly shape and position the mask. Once the roll pattern has been applied, allow it to dry then remove the masking.

  57. Remask and paint any additional accents on the rocket. The control tabs, tips of S-Band antennas, tip of the nose, and the black forward band at the front of the rocket are a good minimal set of details to set off the decals. Additional weathering such as dirt and grime should be completed after application of the decals.Apogee-COMPONENTS-MX-774B-Hiroc-Kit-FIG-61

  58. Apply the water-slide decals to the surface carefully. For the overall best appearance, a decal setting solution can be handy as it softens the decal and helps it conform to the surface making the edge of the decal disappear when fully dry. Allow the rocket to dry entirely.

  59. Optional: If desired, additional weathering can now be added to the surface of the rocket using standard scale modeling techniques. Doing so now (before clear coating) ensures that the details are as robust as possible.Apogee-COMPONENTS-MX-774B-Hiroc-Kit-FIG-62

  60. Protect the finishing and provide a uniform sheen to the rocket by applying a satin clear coat to the rocket using several light coats. Due to the tendency of metallic paints to turn gray with clear coats, the nozzles (in steel) and the tip of the nose (in aluminum) should be masked so that they are not coated. Allow the clear coat time to dry completely before handling the rocket.

  61. Mount the rail buttons on the weld nuts with the 6- 32 screws and mount the washer and nut on the all-thread retainer to complete the rocket. Congratulations, your MX-774B Hiroc is complete!

Launch Supplies Needed
To launch your rocket you will need:

Scan for Extended Motor Chart Rocket Preflight

  • A. Slide the parachute protector up to the nose cone then, to minimize the risk of zippers as well as tangling of the shock cord, z-fold the shock cord by folding several short (2-1/2”, 64 mm) sections of the shock cord together and taping the folds into a bundle with masking tape. Repeat creating bundles for the majority of the shock cord leaving about 1 ft (30 cm) by the nose cone to allow space to work on the parachute.
  • B. Fold the parachute so that the shroud lines all come together, then place the shroud lines onto the parachute in a loop and fold the parachute in half long ways to surround the shroud lines. Fold the parachute again – this time the other way – to shorten the whole package. Wrap the parachute with the parachute protector
  • C. Insert the z-folded shock cord into the body tube, followed by the parachute wrapped with the parachute protector, and finally the nose cone.Apogee-COMPONENTS-MX-774B-Hiroc-Kit-FIG-66
  • D. Install the motor by sliding it into the motor mount tube. The motor needs to be retained to prevent it from being blown out by the ejection charge. This is done with the washer and nut. Slide the washer over the retainer rod and secure with the nut.
  • E. Install the igniter according to the motor manufacturer’s instructions to maximize the chances of the motor igniting correctly the first time.

Countdown and Launch Procedure
As a large mid-power kit, the Hiroc can be flown on motors that will require a large field. It also flies well on smaller high-thrust motors, however, allowing it to be flown from smaller fields. Regardless, care should be taken to ensure the stability of the Hiroc as it is a short rocket, and motors larger than these recommended can cause it to be unstable if nose weight isn’t added. With a motor installed, the rocket should balance no further than 27-1/2” (700mm) back from the tip of the nose to ensure safe flight. Check that the area around the launch pad is free from dry grass and other fire hazards, and as far from trees, powerlines, and low-flying planes as possible.

  1. Remove the safety key from the launch controller (if it has been stored there).
  2. Place the rocket on the launch pad. The rocket should slide freely along the rail.
  3. Attach the clips to the igniter wires. The clips must not touch either each other or the metal blast deflector. Otherwise, a misfire is likely.
  4. Stand back from the rocket as far as the launch wire allows.
  5. Insert the safety key to arm the launch system.
  6. Give a loud countdown! 5… 4… 3… 2… 1… LAUNCH
  7. Press and hold the button until the engine ignites. Once the rocket is away, remove the safety key.

Suggested Motors

Manufacturer Model Altitude (ft.) Altitude (m)
Aerotech E24C-4 414 126
Aerotech F25W-4 1105 337
Aerotech F26FJ-6 918 280
Aerotech F67C-6 1311 400
Aerotech G25W-6 2077 633
Aerotech G40W-7 1735 529
Aerotech G80T-7 2078 634

Misfire Procedure
A misfire is when an engine does not light after the launch button is pressed. This is sometimes a result of the igniter burning but failing to light the engine. At other times, the igniter will not burn at all (this is often indicative of  a short between the clips). To deal with a misfire safely, remove the safety key from the launch controller and wait a full minute (60 seconds) before approaching the pad. Check that the igniter wires or clips are not touching and causing a short. If they were, the short can be corrected and a launch attempted again. If the engine simply fails to light, remove the old igniter and install a new one. Make sure that the igniter is installed into the engine and that it is in contact with the propellant. Always follow the NAR (National Association of Rocketry) Model Rocket Safety Code when launching model rockets.

Manufactured in the USA by Apogee Components Inc. Colorado Springs, Colorado, USA
www.ApogeeRockets.com

Instruction Sheet A: P/N 31284 Updated 03/18/2024

Frequently Asked Questions

  • Q: Are the recommended paint colors accurate for historical accuracy?
    • A: The recommended paints are based on historic photographs and descriptions, making them a best guess. While efforts have been made to ensure accuracy, exact color references are not provided.
  • Q: Can additional work be done to improve the accuracy of surface details and decals?
    • A: Yes, for a competition rocket, additional work to enhance the accuracy of surface details and decals is recommended.

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