Vought F7U-3M Cutlass***FINISHED***

[PeterB]

These days, what with computers, wind tunnels and the like it may seem relatively easy to design a halfway decent aircraft, though there are sometimes exceptions such as the F-35 (OK, I don't quite know why I am unimpressed with that particular plane though I doubt I am the only one), but it still takes a lot of money, skill, experience, hard work and sometimes a bit of luck I think. After all, powered heavier than air flight has only been around for not much over 100 years (depending on which book you read) and back in the late 1940's the arrival of the jet engine was an added complication to what was then far from a perfect science. Some of the early jets designed in the USSR, UK, and US were real lemons whilst many others were, at best near misses, partly from design failings, but also due to problems developing powerful jet engines that not only produced the designed thrust but were reliable. I have already touched on the engine problems in my thread on the F3H Demon and now I am going to build another less than perfect example of a jet fighter for the US Navy. Between April 1954 and November 1957 it seems to have served in up to 13 USN squadrons if the test/evaluation ones are included, but in several cases accidents and maintenance problems resulted in them spending most of their time operating from shore establishments.

 

I don't know about you but growing up in the 1950's I heard mention of a number of US aircraft that sounded rather weird and interesting, but with no internet and very little in the way of other media information knew very little about them. The Cutlass was one, and when I had "grown up" a little and decided to build a kit of one, all I could find were vacforms by Airmodel and Rareplanes. I can't remember which I actually built but I remember I painted it blue!

 

Back in 1987 Fujimi released their injection moulded kit of the F7U-3, followed by the F7U-3M with missiles and the F7U-3P with the extended photo nose, and in around 1990 I picked one up cheap at my then local branch of Beatties in Cardiff - now long gone sadly as I had a "Price Match" card which allowed me to buy anything at the lowest price I had seen it advertised anywhere in the UK, saving quite a bit over the years! It comes with makings for 2 NMF examples and one Gray/White one, but given its age and provenance I will give the decs a coat of MS Liquid Decal Film as a precaution. If that fails I may be somewhat stuffed.

 

The Cutlass was a product at least in part of the German aircraft technical information that fell into the hands of the allies at the end of WWII, resulting in what might be termed the "Buck Rogers" period of design, ranging from the fairly basic swept wing to deltas with and without tails and flying wings, some of which were pushing the boundaries of known aerodynamics at the time, given the research/design tools currently available. I am not quite sure what type the Cutlass should be classed as - some sources say a tailless swept wing even though it did have two vertical fins! With its long nose wheel leg to give it a high angle of attack on take off like most delta winged aircraft, one of its nicknames was apparently the "Preying Mantis". It is often dismissed as an underpowered failure that had a habit of killing its pilots - some sources say that a study in 1957 by Vought found that with around a quarter of the airframes (288 plus prototypes) produced being involved in accidents (78), and 4 Test Pilots and 21 other USN pilots killed it had the worst safety record of any USN swept wing jet aircraft, which may have given rise to another nickname - "Widow Maker". I will fill in some more background as we go along.

 

Pete

[theplasticsurgeon]

36 minutes ago, PeterB said:

It comes with makings for 2 NMF examples and one Gray/White one, but given its age and provenance I will give the decs a coat of MS Liquid Decal Film as a precaution. If that fails I may be somewhat stuffed.

 

Great choice of kit Peter,  remember mine from 2021?  Decals worked a treat, so I really doubt you will have any problem.

I've still got the leftovers in my spares box, so call if you need them.

[PeterB]

16 hours ago, theplasticsurgeon said:

Great choice of kit Peter,  remember mine from 2021?  Decals worked a treat, so I really doubt you will have any problem.

I've still got the leftovers in my spares box, so call if you need them.

Thanks Tim. No mention of ballast in the instructions but I presume that the odd geometry means it is naturally nose heavy?

 

Pete

[Toryu]

Failure or not - I love those US fighters from the fifties. They all look weird indeed but that's what intrigues me even if I'm not a jet modeller. Interesting GB entry!

[stevej60]

Always a head turner Pete what's not to like about the Cutlass?

[Bertie McBoatface]

Fascinating aircraft. It must be a unique configuration. (Until someone knows otherwise.😁)

[PeterB]

3 hours ago, Bertie McBoatface said:

Fascinating aircraft. It must be a unique configuration. (Until someone knows otherwise.😁)

As far as ones that actually entered service perhaps but there were a few quite similar ones, mostly classed as "flying wings", such as the AW52 that Mr T is building over in the "Prototypes etc" GB. The difference between a tailless swept wing and a flying wing seems a bit of a "grey area" to me, in the same way that I have seen the EE Lightning described as a "delta with a bite taken out of the trailing edge" or words to that effect and come to that my F3H could almost be classed as a tailed delta. All depends on your point of view I guess.😄

 

Pete

Edited January 18, 2023 by PeterB

[Col.]

Another interesting subject choice Pete and a lovely kit of it  

[PeterB]

I spent part of today putting yet another shelf up in my roof - I would have preferred to have waited for warmer weather as it was ruddy cold up there and bad for my knee joints and chest, but I suppose it proves that the insulation is keeping most of the heat in! Unfortunately I did not have a lot of choice as my kit storage situation had become critical and I already have 7 recently completed kits sitting around in my work room where they are vulnerable to damage. This was the sixth shelf I have put up there since starting my first GB back in June 2019, but with something like 100 kits built since then they had to go somewhere.😄

 

Anyway, I have managed to make a start on the Cutlass. The cockpit is the usual thing - a tub with side panels, IP, Stick, Seat and rear bulkheads, and comes with the choice of engraved detail or decs. I have used the decs, but may have put too much MS Liquid Decal Film on as they were rather stiff - just hope I have not screwed the others up! Anyway I have made a copy as a precaution. I have not as yet added the top part of the seat as I would probably knock it off.

I have also joined together the two halves of the intake trunking and fitted it together with the bulkhead/fan fronts into the lower rear fuselage. As the trunking is split horizontally there was a visible seam but a bit of work with a cocktail stick, cotton wool bud and PPP has made it less obvious.

 

Contrary to my previous comment there is a small symbol indicating the need for weight in the nose though no indication how much - not a lot of room in there so probably about 5g unless somebody knows better? If I build up the rear fuselage complete with landing gear before adding the nose I should be able to check! I remembered to open up the holes for the wing pylons but not the ones for the belly rocket pack the earlier version had. The pack had either 32 or 44 2.75" folding fin unguided rockets, depending on which source you believe - most say 32. Unlike the belly pack in the F-86D, these were not arranged in two rows one above the other, but one behind the other so they went out of the same exit holes. Of course sometimes one malfunctioned and if you were lucky the one behind would knock it out of the way, but if not then the belly pack caught fire - clearly not the brightest of ideas!I guess they were trying to reduce drag!

 

This being a type that is perhaps not that well known, I thought I would go into rather more detail than I would for say the F4 Phantom II. Info from a number of sources but mostly the Naval Fighters book on the subject.

 

As mentioned in my F3H Demon thread, the USN were a little reluctant to acquire a jet for carrier operations due to a number of factors including low engine power, high fuel consumption and poor reliability but eventually asked McDonnell Aircraft to build what would become the rather pedestrian paced FH-1 Phantom. Once that proved the concept was workable and wanting something rather better, they sent out another request for proposals in November 1944 to 8 companies, and had 4 replies. They turned down the Grumman one as they felt that company was already fully committed, and accepted the other 3 which would become the North American FJ-1 Fury, Vought F6U Pirate and McDonnell F2H Banshee. All were fairly conventional planes with straight wings and only the latter would be built in numbers. Just 30 each of the other 2 were ordered but whilst the Pirate never went aboard a carrier, one squadron did at least take the Fury to sea, and that design was developed into the much improved F2-2/3/4 Furies via the F 86 Sabre.

 

Grumman had their F9F Panther accepted in 1946, having first proposed a plane with 4 small engines, then one with two, but at the end of that year another request for proposals was issued specifying a speed of 600mph and a ceiling of 40000ft and in early 1946 no less than 12 designs were submitted by 6 companies - Martin and Douglas one each, McDonnell, North American and Curtiss-Wright two each, and Vought four, namely the V346A,B,C, &D, all with swept wings. The B and D were relatively conventional designs, the former with two fuselage mounted engines and the latter with two in pods under the wings, whilst the A was a “tailless” design with two fuselage mounted engines, and the C was effectively an A with an extra engine making 3 side by side. The tailless design was apparently arrived at as a result of compressibility problems being experienced on planes such as the F4U at high speeds, and Vought decided that removing the horizontal tail completely was a way of getting round this on even faster machines. On June 25th 1946 a contract was awarded for 3 prototype Model V346A as the XF7U-1 and following on from the Corsair and Pirate, Vought named it “Cutlass”.

 

More later.

 

Pete

 

 

Edited January 22, 2023 by PeterB

[PeterB]

I suppose I delayed building this for so long because I feared it would be difficult, but in fact it is fairly simple so far and the fit is pretty good - that might change when I come to add the nose and intakes, but it is racing away.

As with the AE-6A of theirs I built a few years back, they mould on the tracks for the slats which can be cut away if you prefer them closed, but on virtually all the photos I have seen they seem to be at least part open on the ground. The same applies to the wing control surfaces - what we now call "Elevons" I believe though Vought called them "Ailavators", which are normally drooping at rest.

 

I have added the main landing gear so I can check what weight is needed - turns out 5g is enough though I have added nearer 7g.

There seems some uncertainty about the colour of the interiors of the wheel bays and doors, together with the legs - with the gray/white scheme you would normally expect white and that is how the preserved examples are painted, though the wheels themselves are "silver". The kit instructions and the Naval Aircraft book say silver for everything, which may make sense as when the F7U-3 entered service they were in the silver overall scheme, so the one I will be doing must have only just been painted gray/white and maybe the u/c was not repainted initially? In the above view you can see the speed brakes inboard of the undercarriage, and the well for the "A-frame" arrestor hook which replaced the unsatisfactory "sting" type mounted at the extreme rear of the fuselage on the F7U-1.

 

A bit more history-

The first prototype flew on September 29th 1948, powered by two Westinghouse J34 without afterburners as they were not yet ready, and the Navy was sufficiently impressed to order another 14 as production F7U-1. The story of the development problems is too long for here, but suffice it to say that there were problems with the undercarriage being too weak and collapsing, the engine/afterburners malfunctioning, handling problems and a poor view from the cockpit. All of the prototypes were lost, the No2 one, repaired after the undercarriage failed to extend on landing vanished in early March 1949. The pilot was never found but later some small pieces of wreckage were recovered from Chesapeake Bay. The number 1 and 3 prototypes , now with afterburners fitted, continued the test program but early in 1950 the number 1 machine, testing the installation of drop tanks, started to yaw and roll during take off and crashed, though the pilot was unhurt. In July of that year the remaining prototype burst into flames during an airshow and was lost though the pilot did eject using the Vought designed seat. The suspected cause was a leak in the plumbing for the recently installed afterburner.

 

The production version had modified and enlarged vertical tails and rudders which reduced the tendency to “hunt” found on the prototypes but handling was still a problem. One of the 14 F7U-1 was lost due to control failure and another when the pilot is believed to have suffered oxygen starvation in the pressurised cockpit. The rest were mainly used for testing. The up-engined F7U-2 was never built and the Navy ordered the larger, faster and somewhat improved F7U-3 in August 1950 – whilst the F7U-1 was considered rather fragile, one source describes the F7U-3 as being “built like a Sherman tank”. The first flight was made in December 1951, but the first 16 produced were fitted with the non-afterburning Allison J35 as the new and more powerful Westinghouse J46 was not yet ready. In an attempt to improve the pilot's view the canopy/seat were raised but as that did not suffice, the cockpit was raised even further and rather blunt “bull nose” was also redesigned and made smaller and shorter in the rest of the batch. Many more changes were made, for example over 100 new access doors/panels were fitted and the electrical and hydraulic systems runs changed to make it easier to maintain the aircraft, but besides the new nose shape, the most obvious external changes were the new nosewheel assembly with twin wheels and the repositioning of the 4 x 20mm cannon from the nose to the top of the air intakes, though this was to cause problems as the engines sometimes flamed out when the guns were fired - they did the same also on later versions when Sparrow missiles were fired as they ingested the exhaust fumes! Apparently this was cured by controlling the guns so that they did not all fire at once creating a pressure wave, and by adding vents over the guns to get rid of their fumes.

 

Final instalment next time.

 

Pete

Edited January 20, 2023 by PeterB

[PeterB]

As I suspected the nose/intake to fuselage joints were not the best but not too bad - probably as well I am not going for an NMF version though.

That is one heck of a long leg - 3.3cm so just under 8ft in scale, and that's not counting the wheels, and yes, it is meant to angle back but not I think quite that much so I have adjusted it since taking the pic! The nose leg on the F7U-1 had a reputation for being too weak and collapsing, and to add to the problem sometimes when it came down the single wheel was at an angle to the direction of flight. On the F7U-3 it was modified, strengthened and provided with a pair of smaller wheels. I have a slight problem regarding the wheel doors - according to a diagram in the Naval Fighters book the rear doors closed after the wheels came down, but most of the photos show them open. Of course they could be opened manually for servicing to be carried out and that is how they are usually found in museums so I cannot rely on the walk-rounds where they are also open. I won't be gluing them on for a while so I will have a little think about that.

 

So, final episode of the history.

 

The unusual aerodynamics were still causing handling problems and in the Naval Fighters book on the Cutlass I came across an interesting comment. During testing an aircraft was lost when it started “uncontrollable gyrations” when well within supposedly safe parameters and the same thing happened when an experienced Navy test pilot tried to simulate the same flight – both pilots ejected safely. As the Vought handbook clearly said the Cutlass would not spin, they spoke to a Vought test pilot and he confirmed that he had experienced the same problem but insisted it was not a spin but a “post stall gyration” and when asked what he had done about it he admitted he too had ejected! Later, having enough height to play with, another Navy pilot experiencing this “non-spin” found that after trying all the usual recovery methods with no effect, if he just released the stick the plane would sort itself out (though not always it seems)! Actually, once pilots got to understand the plane some of them actually liked it. They said it was a stable gun platform, rugged and handled quite well, with an outstanding rate of roll. They felt that if it could have had more power it would have been a pretty good fighter. As it was the Westinghouse J46, though nowhere near as bad as their larger and infamous J40, never really delivered the goods, resulting in yet another nickname - “Gutless Cutlass”.

 

The original F7U-3 was, as mentioned earlier armed with 4x20mm Colt cannon and 32. 2.75” unguided rockets like several other designs, but the rockets were soon found to be not much use except at very close range Before entering normal squadron service it was test flown by the so called “Project Cutlass” team at Miramar before being passed on the Composite Squadron VC-3 for further testing. Amongst the pilots who flew it during the testing phase were future astronauts Walter “Wally” Schirra and Alan “Burt” Shepard, and although it never entered service with the Marine Corps, they clearly flew it a few times as another astronaut – Marine John Glenn – apparently flew the type as well. As the unguided rockets were not a success, pylons were fitted under the wings for Sparrow I missiles and the rocket pack removed, producing the F7U-3M. Inevitably, it was found that the wing strong points could be used for other stores such as bombs, and some of the units who flew the Cutlass were re-designated as VA instead of VF. There were 20 F7U-1 built excluding the three prototypes, and these were followed by one prototype XF7U-3, 192 production F7U-3, 98 F7U-3M plus a further 48 modified from F7U-3, and 12 F7U-3P with a recce nose. A further order for 202 planes was cancelled and production ended in August 1955, the Cutlass being withdrawn from service in November 1957 and in many cases replaced by the somewhat slower but more reliable Grumman Cougar.

 

I suppose that like the F3F-2 Demon and the F11F-1F Tiger and maybe even the F4D-1 Skyray, the Cutlass could be called another "almost but not quite good enough" aircraft, or perhaps just more victims of  US Aero Engine development problems, not that those were unique to the States.

 

Pete

Edited January 20, 2023 by PeterB

[Bertie McBoatface]

The model is looking good. Imagine trying to get out in a hurry, for an engine fire on start up perhaps!

 

The dissertation gets an A+ from professor McB. 

[Col.]

Good progress again Pete

 

49 minutes ago, Bertie McBoatface said:

Imagine trying to get out in a hurry, for an engine fire on start up perhaps!

From what I understand the biggest problem with these was the lack of fire about their engines  Sure I once read of a situation where an F7U pilot suffered such a slow throttle response during landing the aircraft stalled onto the deck and he had to taxi up to take the first arrestor wire.

[PeterB]

4 hours ago, Bertie McBoatface said:

The model is looking good. Imagine trying to get out in a hurry, for an engine fire on start up perhaps!

 

The dissertation gets an A+ from professor McB. 

Hi Bertie,

 

Yes, it was a long way down from the cockpit without a ladder! Glad you liked my rant lecture Prof - I had you in mind when I wrote it😄.

3 hours ago, Col. said:

Good progress again Pete

 

From what I understand the biggest problem with these was the lack of fire about their engines  Sure I once read of a situation where an F7U pilot suffered such a slow throttle response during landing the aircraft stalled onto the deck and he had to taxi up to take the first arrestor wire.

Thanks Col,

 

I think slow throttle response was a problem with most early jet engines and Eric Brown often mentions having to come in to land with the throttles wide open in case he needed to go round again - I gather than on the Me 262, if you opened the throttles too quickly the engines would flameout! The Vought ejector seat seems to have been used quite a few times on this plane, but in those days they were no use low down, so landings would have been rather stressful. Getting the right combination of engine power vs reliability seems to have taken quite a while.

 

Pete

[PeterB]

Whilst I like the look of the gray/white planes of this period, the white can be a bit problematic. I can remember my late father when he decided to modernise the panelled interior doors in his house and faced them with a sheet of hardboard. He was a meticulous painter and so applied several coats of undercoat, flatting each one down when dry, before adding at least two top coats of gloss and yet he was never entirely happy with the results when using white - even the then brand new "brilliant white" - though I suspect most of the "patchy" look was down to reflections. In the past I used  Halfords's white plastic primer spray but a year or so ago they closed my local store - they said I could always have stuff delivered from the one 12 miles away but when I tried they did not seem to deliver spray paint for some reason even when the order was over the £25 minimum. I must get some more when next I am in that area but for the moment I hand painted some flat white on the unders and a light grey on the uppers as a primer.

 I will let that dry then make a start on the top coat. In the meantime I may have solved the problem regarding the undercarriage doors I mentioned earlier - the drawing I referred to with the caption saying the doors closed after the wheels extended was for the F7U-1 but the later F7U-3 had a different wheel leg/door arrangement so they probably did stay open!

 

Pete

Edited January 23, 2023 by PeterB

[PeterB]

Getting there slowly. After several thin coats of Gray and white the basic painting is done - I will leave the touching up until I have finished the detail work such as the NMF leading edges etc.

As you can see I have added the tailpipes and the top bit of the ejector seat.

 

Pete

[Bertie McBoatface]

Slow and steady wins the day! 

[paul-muc]

You may control the angle of the nose undercarriage. It stands vertically on the ground. The stabilizer in the wheel bay is too short.

[PeterB]

11 hours ago, paul-muc said:

You may control the angle of the nose undercarriage. It stands vertically on the ground. The stabilizer in the wheel bay is too short.

I had the nose leg on and off several times and reached the same conclusion. I have ended up with it still at a very slight angle, but the some pics show it vertical and others seem to show it slightly raked backwards, though that may be to do with perspective/camera angle. Anyway it is a lot better than it was.

Touching up finished and the strange canopy and windscreen glued on - I can only assume that either it was not yet possible to "blow" a clear one big enough or else they were worried about strength.

 

I have given it a gloss coat and tomorrow I will see if have I wrecked the decs - hopefully not.

 

Pete

Edited January 30, 2023 by PeterB

[PeterB]

This might just work - the decs are just about usable but very fragile. I don't know if the MS Liquid Decal Film has helped or not but they are very stiff and getting the one over the rear of the canopy was tricky even laying it on a film of wet varnish.

I don't know whether I put too much on or whether the decal film has a short shelf life and goes off - this bottle is about 5 years old and I can remember throwing the previous one out as it seemed to be causing problems. Anyway, a bit of careful touching up should fix the bit that broke off in the middle where there was a slit to help with the curvature presumably. I am doing this in the markings of Test and Evaluation Squadron Four (AIRTEVRON FOUR) aka VX-4 "The Evaluators" and this is what Wiki has to say about them-

 

"There were two squadrons which used the designation VX-4. The first was established in 1946 as Experimental and Development squadron Four at NAS Quonset Point equipped with PB-1Ws to evaluate and develop Airborne Early Warning equipment and procedures. In 1950 it relocated to NAS Atlantic City as Air Development Squadron four. The squadron moved to NAS Patuxent River in 1951 where it was disestablished later the year due to the lapse of assigned projects. The second squadron to carry the VX-4 designation was established in 1952 at NAS Point Mugu to conduct evaluations of air-launched guided missiles as assigned by the Commander, Operational Test and Evaluation Force. In 1960 the squadron began to include additional projects that were not associated with guided missiles. Projects such as the operational test and terrain clearance radar, Doppler navigation systems, and air-to-air distance measuring equipment were included in the squadron's tasks.

 

VX-4 flew aircraft that were currently in operational service with the US Navy, and began their life with the Chance Vought F7U Cutlass. Later they transitioned to the McDonnell Douglas F3D Skyknight, redesignated F-10. With the AIM-7 Sparrow missile being used, the North American FJ Fury, Douglas A-4 Skyhawk and the McDonnell F3H Demon replaced the Cutlass and the Skynight. When the AIM-9 Sidewinder came about, the F-8 Crusader was introduced to VX-4, and in the early 1960s the F-4 Phantom II made its debut with VX-4. In the early 1970s the F-14A Tomcat arrived and when the F/A-18 Hornet came to the fleet, it appeared with VX-4 as well, plus newer variants of the F-14 Tomcat. Operational tests and evaluation of airborne fighter weapons systems included the AIM-7 Sparrow, AIM-9 Sidewinder and the AIM-54 Phoenix missiles as well as radar warning devices and self-protection jammers."

 

Pictures show that some planes had plain blue/red on the canopy whilst others had white stars as well. They all seem to have had blue/red tips to the wings which Fujimi does not provide - seems like I will have to do them myself!

 

Pete

[Bertie McBoatface]

I definitely do not miss decaling now that I've moves away from aircraft models. Good luck Pete, with the rest of the frustrations and fragilities of the process!

[PeterB]

Most of the decs are now on and they have behaved pretty well.

As you can see, the unusual configuration means that the vertical tail was a bit "cluttered" as some of the markings that would normally be on the fuselage had to go on it instead - not quite sure why the serial is so ruddy big. Also, unlike most swept wing planes the wing markings were not themselves at an angle, but as with delta wings they were perpendicular to the line of flight. I am making a couple of changes to the colour scheme shown in the kit instructions - I have added the blue wingtips with red lining that VX-4 used, and the flaperons will be white above the wing and below - the kit shows them grey on top and maybe they were in some early cases but photographic evidence shows them white.

 

Pete

[UberDaveToo]

Lt. Joel Premselaar shows how it was quite a climb up to the cockpit of the Cutlass...

 

[SoftScience]

Neat! I've never been able to find this kit, but I've wanted one since the early 90s, when I saw the great Paul Boyer build an excellent aluminum finish plane in an issue of Fine Scale Modeler.

 

 

Yours is looking excellent. I'm really liking the red slats area.

[UberDaveToo]

5 hours ago, SoftScience said:

Neat! I've never been able to find this kit, but I've wanted one since the early 90s, when I saw the great Paul Boyer build an excellent aluminum finish plane in an issue of Fine Scale Modeler.

 

 

Yours is looking excellent. I'm really liking the red slats area.

I found this:

 

https://www.ebay.com/itm/234576430122?hash=item369dd8442a:g:v~QAAOSwfHFimJ~R&amdata=enc%3AAQAHAAAAoDNm%2BApJO8qoez2kBMduBgWvmxMRKuxW2cD3BuGT%2B9nT20I25Qsbj%2BH86QJLmAnfNC%2Bl%2BxHtY9jtAQVpI0MGY4G%2BrEgZs8i3ggViQucBmAl0ZwtRu172PtV%2FlST4%2FJbekLqMsxayVfnIY4dhQKoDEVcPUdOnciO0sE1ckwHR8iinY4t58aZDMzk58RxkhrJIOPCW05LZgBoJFwTj%2BYsxplA%3D|tkp%3ABk9SR4zTpOfCYQ

 

It the Fujimi boxing of the F7U-3P photo Cutlass in markings for the Naval Parachute Unit that was involved with testing dropping sea mines for the Martin Seamaster program.