by Tommy H. Thomason
Saturday, December 2, 2017
Grumman F9F-2 vs. F9F-5 Wing Root Comparison
HERE. The F9F-5 example is a crop from the Howard Mason walkaround photo collection in Prime Portal HERE.
The reason is that the -5 had a thinner outboard wing (10%) than the -2's (12%) in order to delay the drag rise at transonic speed, an aerodynamic benefit demonstrated in flight test of Air Force and Navy research airplanes in the late 1940s.
Since it was desirable to retain the depth of the wing at the wing fold, the location of the wing-folding hardware and the main landing gear, and still reduce the thickness ratio there, the wing and fairing chords were increased on both sides of the wing fold. The change to the leading edge is obvious but it turns out the trailing edge was moved aft as well.
Note that the end of the wing-to-fuselage fairing was relocated aft as well to decrease its thickness ratio as well (on the F9F-8 Cougar, it was moved all the way aft to the end of the fuselage).
Sunday, October 22, 2017
Sword 1/72 North American FJ-2/3 Furies
25 October 2017: Added a discussion (more than you probably want to know) of the nose landing gear here: http://tailhooktopics.blogspot.com/2017/10/fj-23-nose-landing-gear.html
24 October 2017: Added discussion of the shape of the upper nose.
At last, injection-molded kits of the North American FJ-2 and -3 Furies have been released, thanks to Sword Models (www.swordmodels.cz)! It's inexplicable to me why it has taken this long. The swept-wing Fury, like the iconic F-86 Sabre it was based on, is not only beautiful jet but it was dressed in the some of most colorful of 1950s and 1960s markings. Sword has released three high-quality and detailed kits:
FJ-2 SW 72107
The FJ-2 kit has a different fuselage and wing than the -3 and -3M. The FJ-2 had a slightly smaller engine intake, a slightly less deep forward fuselage, and a slightly different air inlet on the after aft side of the fuselage. These differences are correctly represented in the kit rather than making do with the almost identical FJ-3's fuselage. The FJ-2's wing was similar in planform to the F-86E and early Fs with aerodynamically actuated slats. Again, instead of making do with a common wing, the FJ-3 and -3M kits have the notably different, later, so-called "hard wing" with the cambered 6-3 leading-edge extension (and teeny barricade snaggers, although the most outboard one wasn't included). For more on these differences, click here: http://tailspintopics.blogspot.com/2011/04/fj23-fury-redux.html
The FJ-2 was assigned to the Marine Corps and shore-based since it had retained the F-86's J47 engine but was burdened with an increase of about 1,000 lbs in empty weight for carrier-basing capability. It was also one of the airplanes assigned to the Navy's experimental bare-metal exterior project. These are the decals provided with the kit:
As far as I know, all the FJ-3s with the cambered leading edge 6-3 wing were painted gray and white (blue ones would have had the same slatted wing as the FJ-2). These are the markings in the FJ-3 kit:
If you're thinking that not coming from a Japanese model kit manufacture means these must be short-run, relatively crude moldings with 1/4-inch sprues, you will be very pleasantly surprised. The control surface and panel lines are engraved and petite. All the many detail parts such as the pitot look as close to scale as can probably be done in 1/72. The canopy is injection molded in two parts and clear. The ejection seat consists of two pieces, seat and headrest, with very fine face-curtain handles and knee guards (however, it is missing a cushion, backpack parachute, and straps). I haven't checked the fit except for fuselage halves and the wings but so far, so good except that the trailing edge of the wings will require some work to be reasonably thin enough.
I regret to report that the kits are not quite perfect in size and shape. The most notable (but not to the eye) is that the fuselage of both the -2 and -3s is about 3/16 inch (5 mm in 1/72; 13 inches full scale) too long due to a misunderstanding about a length measurement. Since the error is pretty much spread along the fuselage, it would be a lot of work to correct and in any event, really isn't noticeable.
What is slightly off and noticeable, at least to my eye, is the nose. It doesn't appear to curve downward enough, the lower intake lip seems to protrude slightly forward, and the inlet is too far forward relative to the cannon ports (which some don't think angle downward enough):
There appears to be, however, enough plastic in the inlet to cut it back and reshape it if you desire, which also solves the problem of the cannon ports appearing to be too far aft of the inlet lip. Here's one possibility for the -3:
However, some or most modelers will doubtless be happy with the shape of the Sword nose as is. Neither the downward curve on the top of the nose or change in the curve of the side of the inlet lip is as prominent in this picture on an early FJ-2 being evaluated at NAS Patuxent River because the shape of the inlet lip varies with the viewing angle to some extent.
There are some other nits that have been discovered so far. For one thing, the FJ-2 fuselage (but not the -3s) has some "bumps" or bulges that should be removed.
Some wish that Sword had produced the FJ-2 wing with separate slats, since being aerodynamically actuated, they were almost always extended when the Fury was parked or even taxiing. Note that although this was also the static configuration of the F-86's slatted wing, very few kits of the Sabre have this feature either.
The nose landing-gear assembly illustration (seven pieces!) in the instructions appear to suggest that the nose-wheel yoke should be placed on the bottom of the strut. It really goes on the bottom of the small canted cylinder at the front of the bottom of the strut. The yoke itself may be too long but I've haven't confirmed that yet. The top of nose gear door should go into the well a short way, not be mounted outside of it. Also see http://tailhooktopics.blogspot.com/2017/10/fj-23-nose-landing-gear.html
Also the nose landing gear was presssurized for catapult launch to for a greater nose-up attitude.
The windscreen interface with the fuselage appears to need trimming either the forward end of the windscreen or the fuselage where it touches.
There are several threads running in Britmodeller that discuss the kits, with particularly informative and detailed posts by Sabrejet. There are links to a couple of them in my FJ-2/3 post for which a link is provided above. Searching the Britmodeller website (http://www.britmodeller.com/forums/) will uncover more.
Monday, September 25, 2017
Douglas A3D-2P/RA-3B/ERA-3B Skywarrior
Douglas built less than 300 A3D Skywarriors but its family tree had many branches. For a summary, click HERE
Phil Clayton is building the Trumpeter ERA-3B kit with the Steel Beach update set and asked for clarification on the location of some of the details. That led me down the usual rabbit hole of research in the process of resolving some issues that I uncovered in the process of answering his questions.
I hadn't spent much time on the ERA-3B (not to be confused with the EKA-3B, which was a derivative of the bomber) because it was restricted from carrier operations and fulfilled a vital but peripheral Navy mission, training the crews of Navy ships and aircraft to operate in a hostile electronic-warfare environment.
All eight ERA-3Bs were originally delivered as A3D-2Ps, a photo-reconnaissance "Version" of the A3D-2 bomber. Like the other Versions, the interior had been permanently rearranged to provide a cabin aft of the cockpit.
Another distinctive feature was the addition of a periscope sighting system providing a downward view through windows on the underside of the radome.
The view ports dominated the instrument panel (also see https://tailhooktopics.blogspot.com/2023/03/douglas-a3d-2pra-3b-skywarrior-cockpit.html).
When the RA-3Bs began to be supplanted by the supersonic RA-5Cs for reconnaissance, four were repurposed in the early 1970s to be ERA-3B electronic-warfare aggressors, BuNos 144827, 144832, 146446, and 146447. Note that the last two were delivered with the Cambered Leading Edge (CLE) wing, readily identified by the addition of a leading edge slat between the wing and the fuselage.
Side-facing crew seats were added for two equipment operators in the cabin.
The starboard flash bomb-bay doors were secured. The door actuators were unpinned from the doors and door locks were installed if I remember correctly.
The port doors could be actuated externally by either a selector valve when hydraulic pressure was applied or a small hand pump. They were (now) access "panels" for the removal and installation of the ALT-40 and ALR-75 systems equipment."
An escape hatch (19 above) was added above the aft compartment.
Sunday, September 3, 2017
Things Under Wings - Before Douglas High-Speed External Tanks
I've updated my post on the 150 and 300-gallon tanks in use before the introduction of the Douglas high-speed tanks thanks to research by David Collier. See https://tailspintopics.blogspot.com/2016/09/things-under-wings-post-war-external.html
Monday, August 21, 2017
F-4 Phantom ACLS Radar Reflector
Up until now, I'd never seen a good picture of the radar reflector as incorporated on the F-4 Phantom although I'm sure there must be one or more in the F-4 books that I don't have. This was the best I could come up with. There was a door under the nose and a corner reflector extended from the compartment it was housed in.
Thanks to Angelo Romano, we now have one:
Tuesday, August 15, 2017
Relying on Museum Pieces for Accuracy Part 3
6 December 2022: Oops - I relied on an inaccurate Douglas drawing that showed the vertical fin with cambered airfoil that was lifting to the right, whereas the fin itself is angled to the left, therefore lifting to the left. After reviewing Douglas manufacturing drawings with my AD subject-matter expert, Ed Barthelmes, it is clear that the vertical fin has a symmetric airfoil, with a slight amount of asymmetry at the top of the fuselage as it fairs back toward the airplane's center line. I've deleted the error from this post along with the fanciful theory as to why vertical fin was cambered and lifting in the opposite direction to the fin's offset...
Restored airplanes, either static or warbirds, can lead a kit manufacturer and/or modeler astray from an accuracy standpoint. Missing parts, ersatz replacement parts, flat oleo struts, one-off test program modifications, etc. have all resulted in kits and built models with errors. Sometimes, however, what's there is ignored or disbelieved. A case in point is the Douglas AD (A-1) Skyraider vertical stabilizer.
In addition to thrust, the propeller on a single-engine airplane creates other forces that must be taken into account. Consider the following for a propeller turning clockwise from the pilot's point of view. When the propeller is inclined nose up to the relative airflow, the down-going blade produces more thrust on that side than the other, resulting in a turning moment to the left (this effect is known as P-factor). The turning propeller also creates torque, causing the airplane to roll to the left; opposing this requires right stick, which increases lift on the left wing and therefore potentially drag and a turn to the left (some aileron-control designs compensate for this). When the airplane is on its takeoff roll, the torque also puts more pressure and therefore more drag on the tire on the left side of the airplane, causing a turn to the left. The swirl from the propeller, equivalent to downwash from a wing, impinges on the vertical fin, pushing it to the right and therefore the nose to the left.
In other words, a lot of right rudder (which results in a turn to the right) can be required to oppose these forces that cause a left turn. They change with the throttle setting and, in the case of P-factor, angle of attack. More powerful engines and bigger, heavier propellers result in higher forces. The flight-control forces to counteract them decreases with airspeed. As a result, the designer of a powerful single-engine, propeller-pulled airplane sometimes provides a built-in assist like a vertical fin with the leading edge angled left, providing a right rudder effect.
The Douglas AD (A-1) Skyraider incorporates such a feature, with the fin angled left at three degrees.
Although in the drawing above (from the Standard Aircraft Characteristics Chart prepared by the manufacturer) the fin also appears to have a cambered airfoil, in actuality the fin has a symmetric airfoil.
This is my picture of the fin of the AD Skyraider at the National Naval Aviation Museum that shows the angle to the left relative to the dorsal fin that can be seen forward of the red anti-collision beacon.
Byron (SpadGuy) Hukee (see http://skyraider.org/) provided this picture of a Skyraider's rudder.
An even more striking example was provided by Ed Barthelmes (see https://www.amazon.com/1-Skyraider-Walk-Around-No/dp/0897474295) of the AD-5's vertical fin leading edge. Its air inlet and dorsal fin provide an excellent perspective of the fin's offset to the left side of the fuselage.
The old Airfix 1/72 kit of the AD Skyraider incorporated this feature. Some modelers have erroneously gone to the trouble of removing it...
Saturday, August 12, 2017
Relying on Museum Examples for Detail Accuracy: Part 2
I hadn't noticed it until F7U expert Al Casby of Project Cutlass pointed it out to me, but the external tanks are almost certainly bogus. External tanks are not often seen on the F7U-3 (even though it was short on endurance) but if present, they would have been either the standard Douglas-design AERO 150-gallon tanks, the very similar Fletcher 150-gallon tank, or the bespoke belly-mounted tank. These tanks have no fins and their afterbody has a distinctive upward sweep.
I suspect that they are either the 200-gallon tank that was carried by F-86s.
Note that this F7U was delivered to the Pensacola museum with these tanks installed so they weren't a goof by the workshop at the National Naval Aviation Museum.
These are what the F7U-3 tanks should look like:
For other detail issues with this airplane from an accuracy standpoint, see http://tailspintopics.blogspot.com/2015/08/its-not-that-easy-to-get-it-right.html
Friday, July 21, 2017
F-111B Monograph: Buyer Beware
I prefer to write about the also-ran, unappreciated, much-maligned aircraft that were not flown by operational squadrons. Few publishers would consider even a paperback monograph on one of those little-known (in most cases for pretty good reasons) programs. Steve has been willing to front the printing of a monograph on whatever esoteric loser I am interested in writing about, which has sometimes been a loser from his standpoint as well. (You would do us both a favor if you'd order my excellent—don't just take my word for it; see the review on Amazon—monograph on the XFL-1 Airabonita, http://www.ginterbooks.com/NAVAL/NF81.htm from him. He has plenty.)
He did finally sell all of my F-111B monographs that he printed, mainly because that was almost 20 years ago. You'll see that he doesn't include it on his website.
However, it is for sale on Amazon. Unfortunately, some of what is being sold is not one of the originals but a "print-on-demand" version. I haven't seen one but I've been told that that at least some are not very good reproductions, indifferently reproduced on low-quality paper. There is now a review on Amazon to that effect. A known purveyor of them has graciously agreed to stop at my request, but I'm not sure that was the only supplier and of course there are the extant copies.
What to do? I have no control over what's out there and legal action would be a waste of time and money. I can only suggest that you ensure that what you're buying is an original, unless of course you don't need good quality pictures.
For a limited time, you can also buy the monograph directly from me, which will include a multi-page errata document that corrects and augments information in it. For a quote, email me at email@example.com.
Friday, June 23, 2017
F3D (F-10) Skyknight Post Synopsis
I've recently updated one of my posts on the F3D for the variations in the overhead hatch configuration: http://tailspintopics.blogspot.com/2015/04/the-f3ds-of-flying-nightmares-in-korea.html
Two of my other posts on the F3D may also be of interest:
Friday, June 9, 2017
Relying on Museum Examples for Detail Accuracy
It was created from an incomplete F6U hulk by retired Vought employees at the Vought Aircraft Heritage Foundation. For an illustrated description of the process, see http://www.vought.org/rest/F6U_Book.pdf. One entire wing and many other parts had to be created from scratch. As a result, there were some liberties taken.
This is what a production F6U should look like:
Note the difference in the canopy and the shape of the tip tank (the reproduction has simple conical additions to the front and back of a cylinder). Another major error is the location of the bullet fairing on the empennage. It should be directly aft of the stabilizer. Unfortunately, repair of this F6U was begun at the New England Air Museum and this was their contribution.
Vought retirees had to provide the landing gear from scratch so the struts are approximations, available wheels were used, and the outboard main landing gear doors were reduced from two to just one.
At some point between delivery of this F6U to Pensacola in February 2011 and November 2015, a modified canopy was installed to replace the single curvature one. It has more of a bulge but is still not accurate as the bulge is not quite as prominent as it should be and there is more sheet metal on its aft end than it should have. The bogus tip tanks were also removed.
For another of my posts on the F6U that includes links to others, see http://tailspintopics.blogspot.com/2013/03/vought-f6u-pirate.html