Kitty Hawk 1/32 OV-10A/C Bronco Tweak List

By Dave Culp & Thierry Laurent

TYPE: North American Rockwell OV-10A/C Bronco (USAF-USN-USMC)
SCALE: 1/32
COMPANY: Kitty Hawk
KIT Number: KH3204
MOLD CREATION DATE: 2015 (A sprue)
2014 for the other sprues (OV-10D)

TWEAKS LIST VERSION 1.1 (publication date: July 2022)

Compiled by Thierry Laurent & Dave Culp

The following list is intended to help modelers in improving scale accuracy of an airplane model replica. In no way is it intended to support or be offensive towards a scale model company.

As such, it is only the result of a progressive process and is in no way intended to be absolute or even comprehensive. Hence, it is intended to focus on commonly admitted discrepancies and will probably not cover some errors. It is up to the modeler to decide whether correcting the listed issues is worth the time and money he will have to invest in the quest for accuracy process.

No aftermarket correction or detail set is mentioned in this document as the availability of such items may be very variable. Hence, refer to other LSP sections to find relevant information. Moreover, aftermarket sets do not necessarily correct all listed issues. Please refer accordingly to relevant documentation.

GENERAL REVIEW

The OV-10A Bronco was used for a long period by various US armed forces, notwithstanding other countries that used similar or other variants of the short nose Bronco. The kit does not depict one specific configuration, but it has essentially USAF features. Accordingly, it is required to assess the configuration corresponding to the specific user, era and theatre of operations during the half-century use of the short nose Bronco. The tweak list is essentially based on USAF airframes, but the contents should be globally valid for most US short nose Broncos.
The kit is sharing most of its contents with the OV-10D model released the year before. One sprue has been replaced (A) and mainly includes the shorter nose, early cockpit IPs, standard rather than infrared suppressive exhaust stacks, pitot tube and some small parts. This means that some parts are not accurate for some of the versions you can chose. For instance, the various US users relied on different versions of drop tanks. Multiple OV-10D parts are present on the sprues. So, check closely which parts you are using.
The kit is mainly made of 11 light gray styrene and one clear part trees. There is also a photo-etched fret for the seat belts, Garret engine nacelles detail parts and some other small items. Last, one white metal weight is included.
The release has two USAF, two USMC, one Thai AF and one Philippine AF schemes. Note all US schemes are depicting post-SEA war planes.
Shapes & dimensions are correct, and the details are generally accurate even if simplified here and there.
Fit is generally excellent. However, there are some noticeable design flaws that may create huge assembly issues (e.g. the center wing or components in the front fuselage). Unfortunately, the instructions are confusing and lacking correct directions to avoid such issues.
The kit plastic injection design could have been better as there are some sink marks and a lot of ejection pin marks to remove. This is particularly time-consuming to solve in both front fuselage halves and landing gear bays.
The kit has finely engraved rivets. Panel and rivet lines are generally correct even if quite shallow here and there. However, some panel lines should be filled in (typically on the fuselage halves) and the kit does not have the lines of positive rivets that are visible on some parts of the fuselage.
The kit surface has some lines to remove produced by the use of multi-parts molds. This is quite visible on the nose halves bottom.

FUSELAGE (from front to rear)

The fuselage is made of four sections. It is recommended to assemble first each fuselage half with the corresponding nose half (A1+D1 & A6+D6). Strengthen the seams between the front and rear sections with plasticard.
One main rule: dry fit all the main internal components before gluing them as you may have difficulties to close the fuselage halves when all the components of the front landing gear well, the cockpit tub and the rear bay are added. Cautiously trim them before final assembly to get a correct fit.
Replace the plastic pitot tube (Part A13) with an aftermarket one or two thin metal tubes put into each other.
The nose weight is not a drop fit. The locating tabs need some trimming to position it correctly. Secure it with epoxy glue, not CA.
There should be 5 boarding steps whereas the fuselage has only 4 of them. Their location is also a little bit suspect but it is not very noticeable. Add the missing aft-lower one located close to the sponson leading edge.
RHAW antennas are for required some USAF airplanes. The two nose RHAW antennas (parts A16/17) should be rounded and mounted slightly lower.
The FM towel rack (Part F35) was used on the USAF FAC planes but not on all other operator planes. For example, Navy or Marines Broncos in SEA did not use them. If you do not need it remove the two circular supports molded on the fuselage halves.
The relief system evacuation small vent was located under the rear of the fuselage.
Remove all features on the cargo door. Then add the gust lock device at the apex. If you want to open the bay, the door will be open 90 degrees to left, and that gust lock will connect the top of the door to the left boom. Wiring bundles and connectors also need to be added on the black boxes in Part D11.
Various items can be added to cargo bay: Oxygen bottles, radio rack, hydraulic pump, side wall details and insulation (when present), a lot of wiring bundles, etc.
Add plasticard sheet to close off and feather the roof area which extends aft of the cargo bay, over the entry of the cargo compartment.
The kit design is asking for installing the four very fragile M60 machine guns (Parts I25 & I26) in their sponsons before filling and sanding the seams, ending the airframe assembly and go through all the painting phases. It is useless to say this is a quite risky business. Accordingly, it is recommended to modify the machine gun parts to be able to add them at the very end of the painting and weathering process of the model. Unfortunately, this is quite complex if you intend to leave one or the two sponsons opened. Note the M60s were not always used. Even in SEA, some pictures showed USAF Broncos with faired over machine gun holes.

ENGINES/BOOMS

A typical weakness of large scale Kitty Hawk kits is the closing of the removable panels. Getting the engine cowls closing correctly is not that easy and asks for a lot of caution when assembling the Garret engine mounts. It is also required to trim a little bit the inside edges of the boom parts to close correctly parts I1 & I57. If you simply want to close them, it is probably easier to only add the turbine face to secure the propeller. Note as well that modifying the axis to use brass tubing allows the addition of the fragile propellers at the end of the painting process.
If you want to show the quite nice T-76 Garret turboprop engines, some details need to be added (mainly wire bundles and hoses).
Propellers should normally be set at flat pitch (pitch angle zero) when the plane is parked.
Add the missing seam on the engine exhausts shrouds with very thin plastic strips textured with glue and a file.
When forward RHAW antennas are used, aft antennas should also be present under the end of each boom (close to the rudder leading edge). Unfortunately, they are not included in the kit and need to be scratch built.
When an ILS is used (e.g. USAF airframes), the antenna should be added on the right boom sides.
The boom electronic equipment bay panels (Part F-40 & F42) are only accurate for the OV-10D. Such panels are flush and smaller on the OV-10A/C. Putty and sand them fully to rescribe smaller panels. Note some OV-10 got ALE-39 flare/chaff launchers over such panels late in their careers. A small electronic bay cooling vent is located under the boom.
The HF line antenna is missing. It goes from the horizontal stabilizer to just left of the "hump" on the rear fuselage.
Two FM antennas are missing. Insert them into the mounts H33 on top of each tail boom, close to the wing trailing edge. These should be straight, not bent back. A section of thin but stiff black nylon string is a good way to simulate them. If USAF planes had both, USN & USMC planes only had the starboard one. So, only use one H33 part for them.

WING

The structural design of the wing is weak. Without the addition of a re-enforcing spar inside the wing halves, they will significantly droop and there is a risk the seams will possibly break all together. Use thick hard plastic rods or brass tubes glued with epoxy to strengthen them.
Oddly, locating pin holes and assembly guides have been omitted in the wing central section internal side (Part E14). So, be very cautious when assembling the wing sections together. Do not hesitate to add plastic strips to reinforce the seams and ensure all components can be mated correctly. This is critical to ensure the geometry of all the main components (fuselage, wings, stabilizer & tail booms). One error at that step may result in a chain reaction of assembly issues. So dry fit, dry fit, dry fit and trim cautiously the mating surfaces to get a clean assembly.
When the plane is parked with a gust lock installed on the pilot's control stick, the flight controls are positioned this way:
- Elevator slightly up.
- Left aileron down.
- Left spoilers retracted.
- Right aileron up.
- Right spoilers up.
- Rudders neutral.
The kit's flaps are designed with a down angle whereas they should be fully retracted. Remove the flap mounting tabs to position them correctly and do not use the upper flaps extensions.
If an aileron or elevator is posed in any position other than neutral, the "Flettner tab" on that control surface should be posed in the opposite direction.
Oil cooler doors (Parts H25) are opened when landing gear is down.
Eight spoiler panels (parts PE1) are provided whereas only four can be seen at any time. The spoilers come out of the wing top when the corresponding aileron is deflected upwards. Note that when the OV-10 is parked with raised flaps, it is common to see the spoilers on the starboard side up half-way because the ailerons are in a bank right stance.
The center fuel tank cap is missing on top of wing. An aftermarket photoetched set can help to solve that. If you want to do it yourself, copy the features of the four caps already molded on the wing.
The antenna part A21 was not used on US OV-10As.
Two small fuel tank drain tubes with a cut end should be added in the middle of the chord of the wing undersides, on each side of each engine nacelle.

COCKPIT

Double check the location of the separation part F23 between the front and rear stations. It looks the fact the kit was made for both the A and D version disturbed the kit designer when the cockpit parts CAD was done. Moving that bulkhead between both stations closer to the front improves the visual interaction between the cockpit components.
For the same reason, the control sticks (Part H11) are located too far forward. If you look at the front one you will see that it is in front of the throttle (even if the throttle looks a little bit too far back when compared to windscreen frame). That issue combined with a bulkhead located too far back results in a too long front floor section.
The gust lock is a red fabric strap that wraps around the pilot's stick grip and hooks under the right cockpit rail. It is normally installed on the pilot's control stick when the plane is parked.
Do not forget the control sticks should be posed to match the control surfaces stance. The lower part of the stick is hinged to move fore-aft, and the upper part is hinged to move left-right.
Take care when positioning the front IP as this is not a drop fit. Use the windshield part to be sure to locate it correctly. Part A20 is a map container. Its forward face should be closed whereas the aft face should be a flexible flap that closes with a Velcro strip.
The kit does not have the floor armor plates commonly used in war theatre. Some other features can be added on the floor such as the message door hatch or -when installed- the KB-18 camera rear side (between the observer’s control stick and the pedals).
The kit LW-3B seats are correctly shaped but quite plain with missing details. The simple solution asks for replacing them with aftermarket resin ones. Even if you do not want to detail them yourself, you will need to check the following features:
- The canopy breakers need to be thinned and carved (Part 14 top).
- Many features are missing and need to be added on the seats rear, top and sides (ejection rail and details, the inertial reel gas generator, sensor, wires including the headset ones, etc.).
- A large funnel-shaped part is missing on each seat top of late Broncos. This was not visible on SEA deployed planes.
- The seat back cushions need some ‘organic texture’ to be added to lose that plastic part stiff look.
- Add thin ejection handles. Note the upper D-shaped handles are not mentioned in the instructions even if they are present on the I sprues (close to the parachute pack).
- The parachute packs (Part I18) should not be added on the same side of the seats. They should be on the port side for the pilot and starboard side for the observer. The detail lovers will recreate the packs with epoxy putty as the kit parts look stiff.
- Add oxygen hoses clips on the starboard side of each seat.
- If you intend to use the kit photoetched belts anneal them to be able to position them in a loose way. Another option is using the parts as templates to cut new belts in lead foil and add the buckles removed from the kit parts. Note the belts securing the parachute pack on the seat side are missing and need to be scratch built. Last, do not forget the belt locking release latch.
- Multiple positive rivet lines are missing.
- The seat rear armor plates are not included in the kit. The shape of the front seat ones was corresponding to its rear perimeter shape to keep the observer front visibility. The rear ones were behind the channel-shaped sheet covering the seat ejection tube. The plates were rectangular but left a gap between its upper edge and the bottom of the shelf of the circuit breaker panel. Each couple of plates was separated by a vertical seam. Add them for a SEA deployed plane.
- If you want to depict a parked Bronco you need to add the remove-before-flight flag on the ejection seat. There are two pins attached to either end of the flag. At one end the pin goes into the D-handle at the front of the seat. At the other end the pin goes into the ballistic charge which is located about level with the headrest and on the opposite side from the parachute pack.
Most of the protruding knobs and switches are not correctly depicted on the instrument panels.
The observer’s front IP is the USAF type. The USN/USMC types had different bezels with a larger top cowling center section.
The large landing gear handle is missing on the port side of each instrument panel. They should be scratch built as they are quite visible items.
The rear cockpit side consoles of Part F17 are inaccurate. Rebuild the sides without them or replace them with aftermarket rear station sides.
Pedals (G14) should be carved.
Many small details are missing in the cockpit. Whatever may be the version, the full-scale cockpit of the OV-10A is full of wire bundles. Add them with very thin lead wire and/or white color EZ line sections. They are very visible at the front of the rear IP (close to the front seat rear) and close to the rear seat.
Similarly, additional details should be added around the rear instrument panel cover and the cockpit walls. Oxygen hoses, relief tubes and utility lights are also missing on the starboard side.
The front bulkhead part (part F22) location on top of the nose gear well is not very clear in the instructions. Moreover, it is not a drop fit and you will have to trim its sides to position it correctly. Otherwise, the front fuselage may not be closed properly.
The full rear bulkhead (part F24) should not be added behind the observer seat. A cargo barrier made of a kind of covered mesh on a square frame was sometimes used to separate the cockpit from the bay.

CANOPY

The canopy bracing is missing behind the pilot's seat. This can be simulated with brass or plastic rod with copper wire to reproduce the balance bungee going from the top of the seat to the sides of the canopy.
The canopy opening/locking mechanisms needs to be detailed inside the window frames.
Mirrors, standby compass bezel, air vent tube and other items also need to be added and detailed on the windscreen internal side and arch. The kit just gives the sight parts.

LANDING GEAR

The nose tire has a wrong cross section shape. Its center should be more concave. Either correct the profile or replace it with an aftermarket resin one.
Fill as much as possible the injection pin marks on the front wheel well parts or cover them with sections of thin plasticard or photoetched parts where access is difficult.
The plastic cantilever main landing gear strut parts cannot support the model weight over time. There are not many solutions. Ideally, replace the kit gear leg parts with aftermarket brass ones. If you rather decide to use the kit parts, add some degrees of positive camber to compensate for the sag of the flimsy plastic gear and put a temporary foam support under the fuselage when the kit is stored.
The main gear scissor-shaped strut squat switch should only be on the port side.
The landing brake hose is missing on the landing gear struts.
Wiring and hoses are missing in the landing gear bays.

OTHER REMARKS

Check closely the configuration of the plane you want to reproduce as there were small differences between the different operators (at least the antennas) and the configurations (FACs, cargo, medevac, etc.).
All the decal US schemes depict planes used after the war in SEA. Double check them as there were variations in details not covered in the instructions (e.g. propeller blade colors and markings). For example, the black font propeller blade data stencils are missing in the kit decals for the USAF version that used bare metal propeller blades.
The painting call-out in the instructions are debatable to say the least. Choose your topic and check which colors are relevant. One good example: LG wells, doors legs and wheel rims were white rather than light grey.
Thai OV-10C had no underwing stores rack, no AIM-9 capability and a KB-18 strike camera was added (its control panel being located between the windshield internal mirrors). Philippines AF planes were surplus US OV-10A airframes.
The instructions do not mention which of the weapons should be used with the different versions and users. Moreover, some of the included weapons are not relevant for the short nose Broncos. Keep in mind the favorite weapons on such planes were rocket pods. However, LAU kit tube parts look too short and the rocket tips are very basically depicted. Hopefully, multiple aftermarket options are available. Note such 2.75 & 5 inch rocket launchers evolved noticeably since the Vietnam war but they keep very similar external features.
Many other weapons were tested on the Broncos but few of them were extensively used in operations. Besides the ubiquitous rocket launchers, flares, ADSIDs, dumb bombs and SUU-11 or GPU-2 gun pods were used in SEA (mainly by USMC). The AIM-9B were never used in SEA and the AIM-9L never used on the A/C Broncos.
The kit does not include the 230 gallons belly fuel tank typically used on USAF OV-10A planes. The Navy and Marines OV-10A used the Douglas Aero 1C fuel tank. The kit one can be replaced by far better options.
Static discharger wicks should be added (one on the trailing edge of the two vertical tails, one on each rudder training edge and one on each wing tip trailing edge). Cut hairs from a toothbrush, glue each one with CA and paint it black with a brush at the very end of the painting process.
Paint the lights in the following colors:
- formation lights (Parts GP10 to GP17): clear orange.
- left wingtip position light, lower & upper anti-collision lights (Part GP24, GP26 & GP27): clear red.
- right wingtip position light (Part GP25): clear green.
Hand grips can be added above the upper edge of the rear canopy opening section. Similarly, the retractable footstep can be added on the bottom of the fuselage starboard side.
The Broncos were always well-maintained planes. However, when the M60 machine guns were used in theatre heavy soot marks appeared close to their muzzles on the fuselage as well as over and under the sponsons.

The following sources were used to build this list.

Modelling essentials:

Mesko, Jim, OV-10 Bronco in action, n°154, Squadron Signal Publications, 1995.

Scale plans and TM extracts:

Rockwell International OV-10, Famous Airplanes of the world, n°71, Bunrin-Do, 1976.
OV-10 Bronco, Famous Airplanes of the world, n°45, Bunrin-Do, 1994.

Other references:

Naval Air Systems Command, Technical Manual Maintenance Instructions Airframe Systems Navy Model OV-10A, NAVAIR 01-60GCB-2-2, 1977.
Naval Air Systems Command, NATOPS Flight Manual Navy Model OV-10A, NAVAIR 01-60GCB-1, 1980.
USAF Secretary, Technical Manual Illustrated Parts Breakdown USAF Series OV-10A Aircraft, T.O. IL-10A-1, 1968.
USAF Secretary, Operational Supplement Flight Manual USAF Series OV-10A Aircraft, T.O. IL-10A-4, 1968.
USAF Secretary, Technical Manual Power Package Buildup Instructions USAF Series OV-10A Aircraft, T.O. IL-10A-10, 1968.