Supermarine Spiteful and Seafang

[Colin Leighfield]

Hi Martin. Yes, I wanted to use the design principles in the Tucano to produce a similar size (1/10 scale) Supermarine Spiteful/Seafang and see if the flat plate wing could handle the potentially tricky double tapered wing, which in built-up form would certainly need wash-out. Also to have the potential to be built in the same time as the Tucano, which for you might be about 2 days, for me a few months! You said that you'd built one, I think it was the Traplet plan, that it was a pig to handle and you got rid of it!

Here it is so far, just fitted the cylinder block fairings, which need sanding to profile and I'm working on the cockpit which has been tricky, because the back half is cut from one i bought as fire damage when the original Jim Davies shop burned down about 30 years ago! It's a bit discoloured and mating it to the windscreen made from scratch is a bit tricky, but it's nearly there. If the model works and is worth repeating, I'll make a plug and get one moulded in one piece to save the hassle.

I've decided to leave the u/c because it would have to be fixed, with over 600 watts at full bat and similar weight to the Tucano, it should hand-launch ok. I'm fairly optimistic about it and it shouldn't take too long now that I've got stuck back in. When it's done i want to finish renovating the Hughes XF11, then on with the Pushy Cat. Don't think I'll be starting a P51 just yet, I'll enjoy looking at yours instead. I've mentioned this project before in the 2013 mass build thread, I think I'll start a new one for it.

Edited By Pete B - Moderator on 23/10/2013 20:52:52

[Colin Leighfield]

 

 

I moved this here to avoid cluttering Martin McIntosh's beautiful P51 build blog, don't know if it's of interest to anyone. My note to Martin in the previous post explains the thinking behind it and I mentioned it in the 2013 Mass Build Thread.

In November 1942 Supermarine described an intention to develop a new wing for the Spitfire intended to give even higher speed and a very high roll rate, because they thought the Spitfire wing might be getting close to it's limits for very high speed flight and potential aileron reversal issues associated with wing flexing. Their fears proved unfounded because the later 20 series Spitfire wing proved to be very good and had a theoretical reversal speed of 850 mph, way beyond what would ever be achieved in practice.

However, Supermarine worked with the National Physical Laboratory to develop an optimised high speed wing and integrated shallow radiator cooling system for high speed flight, with a laminar flow section similar to the P51. The result was the Type 371, slightly smaller than the Spitfire wing at 35' span and an area of 230 square ft. To simplify production the elliptical shape was replaced by a double straight taper and thicker skins were used in the attempt to get the smoothest possible surface in the interests of laminar flow. Because they expected the wing to have superior high speed characteristics, they made it thicker than the Spitfire wing, improving it's ability to accommodate internal equipment. Later, this proved to be a mistake, because the limiting Mach no. proved to be the same as a P51 at Mach .82, less than the Spitfire.

To test the wing it was fitted to a Spitfire XIV, NN660. On test it was found to be faster than the Spitfire by about 35 mph, but had a higher landing speed and unpleasant handling around the stall, with aileron snatch. After about three months it was destroyed when it flicked over in a tight turn and dived in, killing the test pilot, Frank Furlong. No official cause was ever attributed, but it was considered later that the aileron control rods may have jammed and modifications were made.

The next prototype NN664 had a new fuselage, based on the Spitfire but deepened with a bubble canopy, giving considerably improved forward view. Originally it still had the Spitfire XIV tail. NN664 was used to work on the handling problems and a number of changes were made, including a larger tailplane and fin which were also fitted to the Spitfire 22 and 24, also the Seafire 46 and 47. The handling was improved, but some of the speed advantage was lost. The first production Spiteful was RB515, which was designated an FXIV. RB517 was given the extended supercharger intake as on the Seafire 47 and this is helpful to motor cooling on a model.

17 were produced in all before the RAF order was cancelled in favour of the new jets, but they did extensive development work. RB518 was fitted with a three stage Griffobn engine and is still the fastest recorded British piston engined aircraft, with a top speed of 494 mph.

A naval version was built, called the Seafang and the Navy ordered 150. Spitefuls were converted for initial testing and VG471 was called the Seafang F31, used extensively for carrier deck operational testing.However, the fully developed Seafang was the F32, with folding wings and contra-rotating propeller. After two were built, the Navy cancelled the order because they were happy with the Sea Fury and naval jets were coming. Two F32s had been built, VB893 and 895, but only VB895 flew. However, it and the Spitefuls did a huge amount of development work, the wing going onto the Supermarine E10/44 jet prototype which became the Attacker.

Although a limited success and unknown by many people, I think this is a very attractive aircraft and although not many were made, there is quite a choice between RAF and Royal Navy finishes, different serial numbers and supercharger intake design. I've long wanted to do one and I thought the Nigel Hawes Tucano design principles made a great starting point. I've drawn it up to about 1/10 scale, 42"span and structurally, pretty much the same as the Tucano in build time and materials needed. I've stuck with the flat plate wing for simplicity and the reasons in the earlier email. I'm doing it as Seafang F32 VB895, although I'm not attempting contra-props at this stage!

Here are photos of the hybrid prototype NN660, which I think would make an a attractive and different model in it's own right. RB515, the first production FXIV and Seafang F32 VB895. I don't know if this is of any interest to anyone at all, but if it is I'll take it through to completion and first flight.

Edited By Colin Leighfield on 23/10/2013 22:35:28

[Biggles' Elder Brother - Moderator]

Fascinating prototype Colin and a well written account - thanks for that very interesting.

And the model is looking very promising indeed. My Tuc hand launched really easily with 450W so, even if yours is a bit heavier, at 600W it should be no problem.

It will be interesting to see how it flies. The Tuc was quite nice handling (once trimmed!) but it was quick and bit twitchy on ailerons. The thin wing and relatively high wing loading saw to that. Having said that I found the slow speed handling very benign - its was a bit of a floater in the ground effect when coming in to be honest! I suspect this will be even faster than the Tuc though!

BEB

[Colin Leighfield]

Thanks BEB, I think it's a bit of a risk, but was encouraged by the way that the Tucs built with the properly tapered wing don't seem to have any vices. Also I've found that once the cg and control throws were sorted my "Seacano" flies a treat and slows right down without any tantrums. It's worth a shot, i think it might work out. Soon find out, nothing ventured, nothing gained!

[WolstonFlyer]

Very nice looking model and historical information about the design. Thanks for writing this up

[Ian Jones]

Good idea Colin - like it and watching with interest.

Ian

[Jon Laughton]

Colin

You are a man after my own heart when it comes to all things Spitfire etc. As I did not pick the original thread up in the P51 blog can you advise which plan (if any?) you are using please?

Thanks

Jon

[Colin Leighfield]

Thank you Ian. I'll try not to disappoint. I can't see any reasons why it shouldn't work. Aerodynamically it's actually not so different to the Tucano, although the span is a couple of inches less the wing area is only slightly reduced. The fin and tailplane areas are generous, moment arm is quite long and although it looks a lot sleaker than the Tucano, the frontal area is greater. I don't have a finished weight yet but the wood content is not much different and the power train/Lipo set up are identical. Tailplane incidence is zero to the datum line, wing incidence +1 degree. I've built in 3 degrees right side-thrust, the difference to the Tucano here though is that it has the down-thrust that the Griffon Spitfire/Seafire/Spiteful/Seafang family all shared, which I have translated as 3 degrees relative to the datum. The Tucano doesn't have that so it will be interesting to see how it works.

I will set the cg at 25% mean chord for starters and doubt if that will be far out. I expect it to be well over-powered because although this power set up in the Tucano enables incredible takes off and vertical maneouvres, I'm sure that if I held it flat out in level flight there would be a risk of taking the airframe past it's limits structurally and aerodynamically! If it survives beyond the first test flight and shows promise I would probably knock the next one back to 400/500 watts.

Potential weaknesses? First My nervousness with hand-launching, particularly first flights. However I'm trying to find the time to get in more flying time at the airfield in Fradley and will seek the assistance of some of the real experts we are blessed with in SCRCAC. You. are very welcome to have a go!

Secondly because I was well on with this fuselage before I realised the risk with a front mounted motor when the the one in the Tucano tore itself out and finished up in the garden fence! I changed that to rear mount and it's worked out fine. I had already drawn this one up with a front mount, but as there is more wood in the front and the gluing areas are much greater, I decided to leave it because it would have been a big job to open it up and change the front end around. However, if the model is promising I will draw in a rear mount for the next one.

I've used your post as an excuse for this long reply because as part ot the thinking process in a new project I thought it might be interesting to a few people to follow it through. Also I will do a bit of a "BEB" and write in some more history. I haven't done a build blog, but really it's a Nigel Hawes Tucano structurally and that's close enough for guidance. Again, if there's another one after this, there will be an opportunity.

If at the end it's a total disaster then it will still have been worth it to see what this rare plane looks like in rhe flesh! Hopefully though, it won't be.

[Colin Leighfield]

Hi Jon. Yours crossed mine, just seen it! There isn't one, I've drawn this one up on the back of the Tucano plan. If it's any good, I'll see if I can get it drawn up properly for anyone who's interested.

If you didn't know, there is a Traplet plan for a Spiteful, 51" span which has been up-dated to include retracts. i've never seen one but I think it's the one that Martin built a few years ago and he said wasn't very good. I have a feeling that it didn't have any wash-out and with a wing like this I would normally consider that to be essential. The reason for pursuing this project with the flat plate wing, apart from simplicity for a small/medium size model, is the evidence we have that for some reason this type of wing doesn't have incipient tip stalling tendencies. Clearly if it needed wash-out it would be very difficult to do but I'm reasonably confident it won't be a big problem.

I have got it in my mind that, again if it is successful, to draw up a wing with 3 degrees of wash-out and fit electric retracts, to widen the scope of the design.

Just for interest, I attach some more pictures of this at an earlier stage of construction. You will see how I have concealed the aileron servos in the radiators.

[Jon Laughton]

Thanks Colin

[bouncebounce crunch]

Nice job on the fairings Colin. A very niggly part to get right.

Looking Good.

bbc

[Colin Leighfield]

Thank you bbc. I use very thin micro-ply. It's expensive to buy, but I get years out of a sheet and it is amazing stuff.

I actually haven't got the top line of the fairings quite right, there was a degree of trial and error with this first attempt And the profile is slightly out. However it's close and I don't think will be noticeable after painting. Once again though, if the model is successful I will adjust this on the drawing.

[Colin Leighfield]

Making progress. Airframe ready for final sanding before painting, after sanding sealer, dope and tissue. As the photos show, it looks a bit messy at this stage because I've used bits of blue and white tissue that I had lying around.

I've pushed on a spinner, some work needed there to get it running true and close up the gap with the nose ring. I also intend to make up the exhaust pipes, they will act as an outlet for some of the cooling air coming off the motor.

As I mentioned before, because the Tucano with the wing tapered to scale seems to have no vices at low speeds, I'm hopeful that this will be similar. Wing area is about the same and the airframe weighed as it is, with motor ESC and all servos fitted, but without Lipo, weighs 1164 gms, or 41 ozs. The Tucano weighs 1330 gms, or 47 ozs. The only difference is the paint, so it looks as if I'll hit the target of similarity to the Tucano in all key respects. As the power train is identical, that should be ok too. The main difference is that this is scale, whereas the Tucano is semi-scale, although the build is basically identical.

[kc]

Assuming flight testing goes well ( and we certainly expect it to )can we expect a plan in RCME?

[Jon Laughton]

Thanks for sharing this - I'm finding it really interesting and I for one would be very keen on a plan in RCME

Jon

[Biggles' Elder Brother - Moderator]

Hi Colin, that's looking very good - its going to be a cracking model for sure. Tissue and dope on wood is a very good finish I think for a model this size - lightweight and because there are no unsupported spans very durable I would have thought. What are you planning to paint it with?

Regarding the handling - I agree entirely that the slow speed handling of the Tucano is surprising good. I had expected a fairly viscous stall with that very thin wing - but no its a pussy cat. One thing I did notice (during the relatively brief life of my Tuc ) was a tendancy to be subject to ground effect (remember mine had no U/C and was virtually flat underneath). As I levelled out for the touch down it would "float" as if it was on a cushion of air that couldn't move out of the way fast enough! Not a bad characteristic in itself of course - but it could catch you out.

I once tried flairing a bit more in this situation, to slow things down and see if that would bring her to terra firma a but quicker. Boy that was a mistake! At first nothing, a bit further back, still nothing! A little more and the wing just suddenly went into "airbrake mode" and the model lost virually all forward speed instantaineously! I've never seen a model loose airspeed so quickly - it was like hitting a wall! It wasn't a stall as such I believe - it was just that the sheet wing has a very abrupt drag increase at a certain AoA. So one to watch out for maybe? If it wants to float - I'd be minded to just let it!

BEB

Edited By Biggles' Elder Brother - Moderator on 05/11/2013 13:41:14

[Former Member]

[This posting has been removed]

[Colin Leighfield]

Hi guys. As far as the plan goes, it depends on the mag. If it works I suppose they might be interested in doing it?

When Martin told me about dodgy handling with his Traplet Spiteful, I sent for the plan to have a look. I haven't studied it in detail yet, but at a quick glance I couldn't see any wash-out. With the sharp taper and a normal built-up wing, I would worry about that and would put in three degrees.

BEB's comments are spot on, the glide performance of the Tucano wing is astonishing, but I think there's a sharp increase in induced drag when you pull the incidence up sharply and that would explain what he saw and I have too. I'm on the train right now, I'll try to catch up later.

[Bob Cotsford]

that's looking very good Colin, a unique subject for sure.

Not trying to pile any pressure on but I'm sure we're all looking forward to seeing it at Greenacres next year.

[Colin Leighfield]

Thanks Bob. I'll seriously do my best to get it to Greenacres. It will be ready to fly quite soon, survival might be the true test! Regardless, if it's promising there might be another one by then, if not before. I'm getting the bit between my teeth!

Going back to BEB's earlier observation about apparent ground effect when landing and mine about induced drag at sharp angles of incidence with the flat plate wing, I've also noticed with the Tucano that if trimmed to slightly positive longitudinal stability in normal flight, in a high speed dive the trim seems to change to neutral, as though the centre of pressure moves back a touch. None of these characteristics change it from being very benign though, with no nasty traits at low speed.

I don't think anyone yet fully understands why this simple wing style seems to defy all preconceptions about aerodynamics and the importance of camber, but it seems to do that. It's one of the reasons I'm making this, because it's very handy on a smallish model like this. The Tucano and the Pushy Cat, which also has a flat plate wing, are set up with zero incidence and thrust line, which again begs the question about just how the wing works. The difference with this project is that it's set up with plus 1 degree on the wing and a scale down-thrust of 3. It will be interesting to see the effects and whether I need to make any adjustments later. We'll soon find out.

For further interest, the photos show Spiteful XIV RB516 undergoing armament tests at Boscombe Down. It could clearly carry the kit! In spite of the development delays, if the war had gone into 1946 the orders wouldn't have been cancelled and it would have seen combat service. This Spiteful along with RB517 has the extended supercharger intake, similar to the Seafire 47 and also on my Seafang, which suits engine cooling on a model. It's concealed here by a propeller blade.

Below that is RB518, the sole Spiteful XVI with a three stage supercharged Griffon. It holds the speed record for any British piston engined plane at 494 mph, to this day.

The last one is the first production Spiteful XIV, RB515. This plane is on one of the earlier photos, but this is from a different angle and shows off the markedly different (and less aerodynamically efficient) wing, to the Spitfire. I think it looks good, even so and at model sizes, it"s fine.

One final comment, when trying to work out how the changes to deepen the fuselage and give the pilot a much better forward view were done, I found that if you superimpose the Spiteful/Seafang fuselage profile over that of a high back Griffon Spitfire such as an early MkXIV, the line back from the cockpit to the tail is the same. What they did was to raise the cockpit floor in the original fuselage, put the canopy at the level that coincided with the earlier cockpit roof, then re-shape the nose panels to give a smooth sloping line down to the propeller. Basically, it's the same fuselage and was one of the reasons why altering production from the Spitfire would have been easy, which was important in war time when maximum production was essential.

 

Edited By Colin Leighfield on 05/11/2013 21:21:09

[Colin Leighfield]

Just noticed I didn't answer BEB's question about paints. I will use Spectrum/Spectra matt dark sea grey and duck egg blue. Actually I think the plane might have been polished in the interests of laminar flow, but rather than use gloss paint, I might try polishing after painting and applying the decals kindly made for me by Tim at Model Markings.

[Colin Leighfield]

Next steps. After the first coat of dark grey on the upper surfaces, needs some careful rubbing down and detail before next coat, Spectra/Spectrum paints. The underside will be duck-egg blue.

Specific details needed then to finish will be :-

1. The exhaust pipes, a bit fiddly but not difficult and will be functional in releasing cooling air from the motor area. I'll need to make some ventilation provision further back to get air over the ESC and battery. It's occurred to me that it would have been a good idea to put the ESC into one of the radiators. Next time?

2. The 20mm Hispano cannons. Although tending to be vulnerable, these aren't too long and I'm hoping that the radiators will keep the wing adequately clear when skidding along the grass! When testing RB515, Pat Shea-Simmonds suffered an engine failure and did a belly landing on the grass at Farnborough. He said that there was very little damage, because " the Spiteful had a large wide-span radiator under each wing and slid along the grass on these; it felt just like putting down a flying boat on water". I'm hoping that my Seafang will do that and I've made the radiators robust for that purpose.

3. The spinner. That's a potential problem because it's not a commonly available size or profile. However, about 30 years ago, Micro-Mold did a very nice 1/10 scale (44" span) Spitfire 24/Seafire 46/47 which I built and still have. That included a moulded spinner. It was really too flimsy for a starter motor on the OS25, but ok otherwise. At the time, I bought a spare, which I still have. I must have had a bonus or something because I had two aluminium spinners professionally spun and I've still got them. They are identical to those on the Spiteful/Seafang and you can see on the photo that I've showed the plastic one and one of the aluminium ones as well. There's a bit of work to do on fitting whichever I use, but it has occurred to me that one of the aluminium spinners might serve very well as a master for getting some more plastic versions moulded. Co-incidentally I've bought a Hobby-King Spitfire 24, which I'm impressed with and flies well. That also is 1/10 scale and 44" span, identical to the Micro-Mold version. It's accurate in profile and I thought the spinner/prop combination from that might be a possibility for this project as well, however it is actually slightly smaller than scale. I'm not saying it couldn't reasonably be used, but the model would need some slight alteration to accommodate it.

The other part that is specialised is, as usual, the canopy. As I've mentioned before, I've made one up by attaching the back end of an old commercial canopy to a windscreen I've made. Not perfect, but it's reasonably accurate. Eventually I should make up a plug and get one moulded.

Hopefully I'll make reasonably quick progress now, although I can't get to it every day.

[Colin Leighfield]

The days go by and there's always something that gets in the way, but a bit of progress. Linkages all sorted out and second coat of paint applied, ready for final rubbing down and doing a proper job of finishing it off. These two pictures will lead to the question how I have the nerve to work in such a pigsty of a shed, but I know where everything is (almost)! and I will tidy it up when I've finished this one (Honest guv).

This is the late war up to I think 1949 scheme, with dark grey top right down the fuselage undersides, duck-egg blue underneath. In 1950 the Navy moved the duck-egg blue higher up the sides and made what I think is the more attractive scheme I used on my "Seacano" representation of the 1950 KoreanWar scheme used on Seafire 47s and Fireflies flying off HMS Triumph. I don't think the Seafang was flying by that time though.

Next job is the spinner, then the cannon and finally the exhausts. I will get there!

[Danny Fenton]

That looks great Colin really good build, should go well
Cheers Danny

[Colin Leighfield]

Thanks Danny, I'm taking it seriously and will do my best.