Supermarine Spiteful and Seafang

[Colin Leighfield]

Right, back to this one now that the Pushy Cat (Super Venom)! is ready to go. I've been worrying about an excessive gap between the nose ring and the spinner. This is due to poor planning by me at the design stage. In going for the front mounting I didn't accurately work out how much spacing I would need on the mounting to get the gap right and I'd got about 6mm, too much. I was thinking that going back to square one I should have used a rear mounting for the motor, should I bite the bullet, open up the nose and alter it? I decided to do that, but when I had cut the nose open (weep) I realised that the front end is so solid there's no priority in doing it, just packing the motor back with a good secure spacer and longer screws will do a perfectly good job. I will however show the rear mount on the drawing and if I do another, that will be it.

I had put a lot of effort into getting the nose profile right so had to swallow hard, you will see from the photos the level of destruction! However, once I have put it back together, with a bit of TLC you will never know, so here goes.

Edited By Colin Leighfield on 07/02/2014 20:59:47

Edited By Chris Bott - Moderator on 07/02/2014 22:47:32

[john stones 1 - Moderator]

you don't see many of these Colin

I test flew a Traplet one a few years ago, belonged to a member of club

he'd made a beautiful job of it, proper scale look retracts the lot, standard size servo's i.c.

weighed a lot for its size

took off and flew lovely, i'd tested stall high up brought it in to land and it went home in a bin bag

looking at yours wing loading is going to be way under his

I think advances in electrics and smaller servo's plus a flat sheet wing would give you a very good chance of being successful

i'd wish you luck but don't think you'll need it

[Colin Leighfield]

Thank you John. I've put a bit of thought into it and I think it will work, hand-launching is the nervous bit for me. It's got enough poke to go vertical though, so should be ok.

[Colin Leighfield]

I've finished up re-positioning the motor to get the right clearance for the spinner. Also tidied up a bit inside and put the ESC on the floor instead of the fuselage side. I will make proper accommodation for the Lipo, then put the nose back together and sort out the finishing off. I need to do a proper job of the spinner, finding it quite difficult to get a really accurate mounting of the spinner cone on the base to get it running true but will persevere. I noted that Danny Fenton has used this style of spinner on his Hurricane. I've got two I had spun out of aluminium as well and I will ask Steve at Vortex if he can use one of those as a plug to make me some more plastic ones.

Some pictures, also one from Eric Brown's book "Wings of the Weird and Wonderful 2" in which he describes that the small performance advantage of the Seafang over the Seafire FR47 combined with its' much higher landing speed into the arrester wire meant that it was not the preferred choice. It's interesting though that the Attacker using the same wing and weighing more was put into service and operated successfully off those same carriers a few years later. I don't question Winkle Brown's judgement though.

[Tony Bennett]

that looks nice.

[Colin Leighfield]

Thanks Tony, it's pretty small beer compared to your efforts though!

[Danny Fenton]

Hi Colin I think the reason I get away with my vacformed spinners and plywood backplates is to do with the low rpm I use. Getting some ply that is really flat is also a problem. Don't forget the radius where the motors threaded section meets the prop backplate, it often means the spinner backplate needs the central hole releaving too.
Cheers
Danny

[Colin Leighfield]

Thanks Danny, I take your point. I've had an email back from Steve at Vortex and he says there's a risk of bursting at high rpm, so only recommends using them for PSS. I was a bit surprised because I used the original Pilot moulded (ABS)? white plastic spinner on an OS25.

However, commonsense is beginning to say use the aluminium version. I thought plastic would be better for electric but perhaps not. It does emphasise though the potential difficulty in scale models where the spinner is unique. The Griffon Spitfires/Seafires/Spiteful/Seafang are certainly in this category. Perhaps another way is to turn one out of foam and use light glass cloth with Ezekote or something similar. In the meantime, I'll get on with trying to set the aluminium version to run true. It's amazing how much time it takes trying to sort out details like this, but you know all about that of course!

[Graeme Poke]

Hi Colin, Any progress on this project. I am very interested in the Spiteful/Seafang and am keen to know how it flies.

All the best Graeme

[Colin Leighfield]

Hi Graeme. I allowed myself to be diverted by the mass build for Greenacres 2014 (Pushy Cat modified to look like a DH Venom) and Nigel Hawes's Can Doo, thinking that would also be an interesting one for Greenacres.

However I haven't lost sight of the intention to bring the Seafang to Greenacres as well, because there seems to be quite a lot of interest in it and I've had ideas about doing this for a long time. In fact I've also got the drawings that I scaled up to 1/6 (70" more than 25 years ago!

I've been away a lot this year as well and I'm actually in Spain at present, but will be back later this week and intend to get straight on to finishing the Can Doo, which is nearly done.

I wanted some breathing space on it as well because of sorting out the difficulties with the unique spinner shape and getting the clearance right between spinner back-plate and the nose-ring. That is resolved now, so there's not much to do. Radio and servos are in and everything is working. It will be ready to go in May and I will be posting on this thread again shortly.

The final "pondering point" has been about the launching issue! I'm nervous about doing this with low wingers from old experience and the solution of fitting retracts on a deliberately simple design of this size with a flat plate wing isn't realistic. Neither is a fixed undercarriage, it could be done but I want this one to look right in the air. I've considered making a wheeled bogie because they can work well. However, I've suddenly found that I can under-arm launch the Pushy Cat very easily, something I've been scared of suddenly seems to be practical. Therefore I'm going to try this technique with my (Sea)! Tucano and if I can do it, I will (1) take the wheels off that and then use this method for the Seafang. It's the obvious solution, but I'm naturally slow.

So you will see it again soon on this thread. I don't see why it shouldn't be ok because it's actually and deliberately very similar to the Tucano in all key areas. The next step will be to dust off the 70" drawings and start working on that. In the meantime, I'm looking at another even more unique Supermarine prototype which could be of interest to some and should be able to start a thread on that shortly.

[Graeme Poke]

Thanks for the update Colin. I look forward to seeing the final result.

Now, a 70" one would be just the ticket. That's the size that I would love.

Cheers, Graeme

[Electriflier]

You know, how refreshing it is to read Colin's posts. Informative, factual, well-written and always interesting. Keep 'em coming Colin!

70" Seafang?......... Yes please!

Roy

[Danny Fenton]

Hi Colin I think Steve at Vortex is covering himself. I have not had one of my vacformed spinners let go, but he is quite right they may fail if stressed to high rpm. My limit seems to be around 7000 rpm max. And normally half a dozen screws around the perimeter. My Sea Fury and Chipmunk both have vacformed spinners, as does the Hurricane and Bistormer, but the Sea Fury and Chipmunk are more of a yardstick as have about 50 flights each.

Cheers

Danny

[Colin Leighfield]

Thank you Graeme,Electrifier and Danny. I've always been a 'plane enthusiast and as a kid read everything I could find. The fascination has never gone away and this forum is brilliant for the opportunity it provides to share with and learn from like-minded people.

As far as the moulded spinners are concerned, I think that Danny's right in his suggestion that Steve at Vortex is covering himself. Liability issues can be such a problem that he is rightfully being ultra-cautious. Who would blame him? He's not refusing to supply, just refusing to endorse the application. What we decide to do is down to us. Danny's practical experience is more important.

The 70" Spiteful or Seafang is a definite possibility. I'm trying to get some kind of plan into what I do in the next two years. There's always a risk of being distracted by something that looks quick and proves not to be(!), however this Seafang needs to be ready for Greenacres and hopefully will survive test flights to get there. If it does work out I'll see if the drawings can be improved in case anyone else wants to have a go.The Chipmunk build will commence in October and will be timed to synchronise as well as possible with the others who are doing this.

The Supermarine prototype I referred to is something that Dylan Reynolds is currently working on for me and hopefully will be well on its' way by the time we start on the Chipmunk. Hopefully I will be able to start the thread soon. I'm seriously considering asking Dylan to look at my 1/6 Spiteful/Seafang drawings and commissioning him to do the CAD work and laser cut the parts.

Finally like many I'm seriously impressed by the 86" Depron Spitfire and it hasn't escaped me that this approach is a possibility for the Spiteful/Seafang. However I'm not there yet and I've only just ordered a load of Depron to have a mess with, I may take some time! We'll see.

Other already "built but needing work" projects are my 70" Westland Welkin (not yet flown) and 55" Hughes XF11 (which has flown very well). Finally another one that drew my attention a long time ago and is also drawn up at around 70" span is the Wicko Warferry. If I can work with Depron, maybe that's the one for my first serious attempt to use it for a scale model. In the meantime, I'm thinking about following Chris Bott's lead and using it to make a Tyro! That could be the perfect start.

[Chris Bott - Moderator]

Posted by Colin Leighfield on 29/04/2014 18:43:21:

I'm thinking about following Chris Bott's lead and using it to make a Tyro! That could be the perfect start.

Thanks for the vote of confidence Colin but the depron Tyro is by a different Chris. (Who is indeed another Greenacres member).

Looks good though doesn't it? and I agree it looks like a great place to start.

[Colin Leighfield]

Sorry for taking your name in vain Chris! However, it looks like a good starting point to properly try this stuff.

Another diversion from track "but it won't take long"(!)(?) Oh dear, the number of times I've thought that!

[Erfolg]

Colin

My Canard is using AG 03 which is 6% thick, I think the rest are thinner still. Pretty much so called flat plate airfoils, although cambered just 2%. I came across the sections whilst surfing looking for information on flat plate sections. Ther has been a lot more work done with them than I at first assumed.

Paradoxically a true flat plate is pretty poor, with a rapid drag rise, as the AOA increases, with poor stall..

However if there is a an rounded entry that ramps up, and then tapered shaped back end. Then it would appear the section starts to work well, although the stall can still be sudden, depends upon who you believe. Or it could be all down to subtly of how it is shaped. Although the leading edge may appear to be irrelevant. A square edged, as a plank, is particularly poor. I have seen many differing claims on the max CL, I believe it to be lower than usual at typically 1.4, some claim 1.5 on the basis that somehow the section is more efficient.

With respect to the Seafang it looks good, very good.

What about a Martin Baker MB5? Using the same techniques.

I hope to see it, and I am wondering when is Greenacres?

Edited By Erfolg on 29/04/2014 19:50:41

[Colin Leighfield]

Thank you Erfolg. The wing on the Seafang is sanded to the same kind of profile as used on the Tucano and Pushy Cat, which gives a reasonably normal flat-bottomed aerofoil, albeit very thin and with maximum thickness sustained fairly well back laminar flow style. How important it is I'm still not sure, particularly when you see the way Pete Wilbourne's Can Doo performs with flat unprofiled Depron for wings and foreplane. I suppose that with a model like this, it is important to look reasonable and therefore careful sanding to give a reasonable aerofoil section is essential anyway.

I'm interested in the MB5 as well, but it's been done quite a lot already. However, overall it's quite an easy shape to do. There are a lot of very interesting WW2 and early post-war piston fighter prototypes which don't seem to have been modelled much, if at all. The frustration is not having the time to do them all. We can only try!

Greenacres is the weekend of 22/23 June.

[Erfolg]

My canard wing is Depron to.

I settled on AG 3 on the basis that if a wing is made from a plank, say 6" wide and is 0.375 thick, then the thickness is 6.25% thick, which equates it would seem pretty much with a lot of plank type wings, not being that much of a plank in reality.

[Colin Leighfield]

On with this now. Finished working around the engine mount, still not completely happy around the spinner but getting there. Solved the problem of how to get scale looking exhaust pipes which actually let air through from the cowl by using heat shrink tube! Cut into short lengths and glued in place it's rigid enough to do the job.

Next will be the cannons. Late in its' life VB895 was fitted with short barrel versions of the 20mm. Hispano, so I will reproduce those because they will be less vulnerable than the original longer barrel version.

All the electrics, servos etc. are in and working. Finish painting, put on the scale decals produced for me by Tim's Model Markings and we're ready to go.

[Graeme Poke]

Now then Colin, I can see that you are a very busy man what with Mr. Mitchell's bomber and the Chipmunk and all, but...is there any chance that there may be some progress on the poor old Spiteful/Seafang?

Cheers Graeme

[Colin Leighfield]

You're quite right to ask Graeme, after continuing frustrations in trying to sort out the spinner and allowing myself to be diverted again by the mass-build, I ran it up last week and the shaft of the XYH 3536 motor sheared off at the bearing housing and the prop and spinner hit the side of the shed. I'm baffled because the motor had never flown and it's identical to the one in the Tucano.I've got the replacement and it's going in tonight. I didn't want to post anything further until it was well sorted, but it won't be long now. The reason I kicked off the 317 last night was because I couldn't do any more with the Seafang until some bits I ordered from 4Max yesterday arrive, but their stuff normally comes within 24 hours.

So, after a deep breath, nearly there.

Edited By Colin Leighfield on 12/08/2014 11:13:52

[Erfolg]

What sized shaft does the motor have? As you have written, it is hard to imagine a shaft simply shearing in the manner described, when never previously run.

I have had motors tearing themselves out of the model. In my case on my Ta 152H, although it gave a warning, in that vibration started suddenly, at a particular point in the rev range. After several attempts, checking the prop balancing etc, driving on through the particular revs, there was a bang and the front of the model was torn of. Which is different to your issues.

At least your problem left the model intact.

The spinner looks particularly impressive, I guess you purchased it?

Better luck tonight!

[Colin Leighfield]

Surprised me too Carl, no previous vibration or warning. It looks like a brittle fracture. I'm in the office at the moment, will post a picture when I get home..

[Colin Leighfield]

Here it is, the shaft is 4mm diameter. Because I'd had so much trouble getting my ABS and spun aluminium spinners to run true, I searched ebay for something close and came across one very similar to the Irvine type, but in a longer profile, so bought two. To my astonishment, they seemed to be slightly out of true as well! It finally sunk in that perhaps the shaft was slightly bent, though I don't have a clue how it could be. Anyway, I thought I would give it a quick run-up and bang! The shaft snapped. I don't know how it could have been bent. The motor has only been briefly test run on a few occasions and has never flown. Anyway, I've replaced it with an Expert series motor from 4Max, so we'll see what happens next.