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It’s not every day that something really special comes along, but the more I fly my new creation the more I like it……

So it began a little while ago, while flying on my Northerly slope, Jeffery Hill, I was having a chat with a great bunch of guys also making the best of the North facing ridge. Talking about models of course, they were enthusiastic of my collection of flying machines. It was through one of these Rivington Soarers that I was put in touch with another of their group, Mick, who wanted a new set of wings for his Jart. Well one thing lead to another and during a meeting in my workshop I was invited to Winter Hill, at the heart of the Rivington soaring association slope sites and not too far away either.

A good North Easterly was blowing and it was duly arranged to meet up on Winter Hill under the TV Aerial mast. I wish I’d met up earlier in the day , as the conditions were fantastic - a really nice ridge just a very short walk from the cars and a good breeze. A lively bunch of modellers were already there making use of the strong constant lift.

 There were a good selection of models on show; a Typhoon mouldie, Vulcan bomber, BD5 and many more. One of the models that was putting up a lively performance was a flying wing called a “Poky 40” and I was quite taken with how quick it was. A few of the usual questions of what is was and where did you get it saw me researching the Poky on the ‘net.  

A few weeks on and a moment of daja vu when I was chatting with another good friend from down in Staffordshire who wanted one of my Evolans that he said had also taken receipt of a Poky from the Germany company at www.stratair.com

The seed had been sewn and it wasn’t long before I was challenged by a few good friends to make a model that could possibly rival the Poky. I had been thinking of such a project and as I already had a baseline from which to work it didn't take long to make a start. So over the next couple of weeks using my Evolan model from which to develop a new faster model, I formulated a set of dimensions and had a selection of aerofoils to choose from. A set of vac bagged wings soon took form and I made a lost-foam epoxy glass fuselage to suit.

A couple of new thin Emax 3352 servos had arrived in the Xmas post, so roll the clock forward to current day having been away for the festive holiday, I was desperate to get back in the workshop and onto a hill to fly. It didn’t take more than a few days to finish off my creation, paint and install the radio. The model was taken to my local farmers field for a test launch which confirmed the C of G at 18% was a good starting point and with no trim change it was ready to get it out on to the slope.

The following day, New Years Eve (‘18), I managed to get up onto Parlick with a nice Westerly wind gusting 25mph. For most, it may have been a little too cold especially with the wind speed and the associated wind chill, but I was not deterred. I know the hill well and this type of model just begs for some good compressive lift so I didn’t have any concerns with such a wind speed for a test flight.

Having checked out the conditions with my Evolan, I then chose to launch the new model. Following the necessary pre-flight checks it was launched into the big blue yonder. Not so much blue, a cloudy dull day actually but with some good lift. I had dialled in a little too much reflex for the launch which saw the model climb straight up, elevator style from the gentle chuck. The launch reflex had been set up on a switch so having cancelled this, the model just started to build up speed, faster and faster with only a few tweaks on the elevator trim.

The C of G was indeed a good balance, with little tendency to pull out of dives on its own. Rolls were not as crisp as expected but were good but needs a little more throw to achieve. The stall was non-existent through normal control inputs.

Tight turns were surprisingly good with little speed lost and I was soon into the groove so to speak. Loops, rolls even a bunt didn’t over challenge this speedy little model. Not a model to take your eyes off while flying though, as it covered a huge amount of sky very quickly but a model that certainly gave me a buzz and a big, big grin!... A success!

A few passers-by, ramblers making the most of the dry weather asked the usual questions; that’s unusual, Did you make it, what is it etc, leaving me with a dilemma…… what was I going to call it,  so I have temporarily given it a title of “Wotz@” (Wot-zat) for obvious reasons.

Well that’s it for now as Breakfast is calling, and given that the first day of 2019 is sunny with a Northerly breeze, I’m going to go to Jeffery Hill to fly my new creation a little more, along with my usual go-to models, Evolan, Midge etc.

The first flight is now on Youtube at the following link

The first day of 2019, saw a light breeze from the North, but on arrival at Jeffery Hill, the wind seemed too light to fly. Even the Paragliders were having problems getting airborne.

I did commit the new model to flight and managed to fly it around gently for a few circuits but the wind was too light. I tried one of my other models, but the conditions proved too light also, so I went home.

The weather over the following few weeks has not been too kind, given low cloud, rain but good times will return and I’ll be ready.

In the meantime, being so pleased with the model I am already making a plug for the fuselage mould and have cut another set of wings with slightly different dimensions to compare performance. Time will tell.

Happy New Year for 2019.

Roll the clocks forward to what is now approaching the end of January, the weather being pretty poor since the first flights, and the forecast to be much the same for the next week but Sunday 27 Jan saw North – North Westerly wing a forecast of wind speed between 40 and 57mph. Well it turned out to be a bright day with sunny intervals and the clouds were moving pretty fast. Not to be deterred, I thought I would venture out to Jeffery hill to see if it was flyable. On arrival a couple of other modellers had just arrived with a collection of foamies, SAS “Wild Things", I think.

After the short walk with all my cold weather kit on, I checked the wind speed. The forecast seemed a little excessive, it actually measured 35 - 49mph, although during my first flight it seemed like the occasional gusts were much stronger causing me to find a better footing to stand upright.

Once again, the “Wotz@” just ate up the sky giving so much confidence in its controllability and leaving the heavily ballasted “Wild Things” almost stationary in comparison. I had slightly increased the aileron deflection which improved the roll rate with no trepidation in flying the pocket rocket around. The model just oozes confidence and one that I just want to fly more and more.

I have decided to make a proper mould for the fuselage and to try a slightly higher aspect ratio wing as a trial to find out if indeed I have already got the perfect formula or if it can be improved a little more. How? Well I don’t know but it’s worth having a play with a slightly different wing to compare.

In the meantime, I am wishing for some nice weather to go slope soaring again soon.

Making the fuselage mould has being somewhat eventful with problems with tooling gel coat and release agent. I used to use Polyester gelcoat and resin for my moulds and have not had any problems until I started the Mould for this model. A few trials and tribulations, I’m playing it all down a little......... its been a Trial!!!!! lots of lessons learned and I now use epoxy for my moulds. Much easier to work with, although a little more expensive, I think well worth the investment and I’m now back on track.

I also decided to make a mould to utilise an internal bladder system to help improve the fuselage mouldings. The inflated bladder pushes the cloth into all the nooks and crannies, it makes a better job of the seams and actually pushes out unnecessary resin, which results in a strong and much lighter fuselage. This technique was new for me, but a few you tube training videos later, I’d got it sorted, and the added bonus, is that it doesn’t take all day to get the two halves of the mould joined. From start of the lay-up to joining now only take a little over a two hours, where before, a couple of hours to lay up then wait till the resin has gone "green" before trimming and joining. effectively an all day event which need a planned approach.

The use of modelling balloons to inflate from the inside of the fuselage can be seen in the photo. Clear resin, with balloon pulling the guide tube and balloon adding colour to the moulding until it is removed. Removal of the balloon is fairly easy given a little patience. Gently pulling the tube and the end of the balloon see’s it releasing from the internal contours of the fuselage.

Once the resin swarf is trimmed from the moulding seam then everything is good to go, with just the cockpit and wing wiring openings to cut out.

Feedback from friends who had me cut them a few wing cores, which they married up with a range of home brew fuselages, has been useful. Whilst the little 40” model continues to blast around the slopes, a new idea that was suggested was to increase the wingspan a little to see how it would fair against the original design. A set of 48” cores for a friend which were vac bagged with 100g uni-direction carbon making for a really strong wing. He married these up to a homemade lost-foam epoxy glass fuselage, which worked really well. The vtrst flight was good and later putting 7 oz of ballast in it made for big manoeuvres with the model retaining energy well.

Another good friend had me cutting a set of 50” cores for him and I decided to put one together for myself as well, which I planned to marry up to to the first moulded Wotzat Fuz.  Given the steer and a source of 100g uni-direction carbon from Easy Composites, I also laid up the cores with a layer of 100g uni-carbon and 80g glass in the vac bag and with the addition of a carbon leading edge, I have been so pleased with the results.

Without waiting to paint the model, I cut and freed the living hinges for the Elevons and fitted the gear. 2 Emax 3352 MG servos for the wings and a 2/3 AF NiMh and mini receiver to the Fuz. A little moulded nose weight and I had the model balanced at 18%.

The first flight was in fairly light conditions which saw the model buoyantly flying lazy figure eights with good speed. The following weekend, had me travelling down to the Leek and Moorland slopes joining a good crowd at the Mermaid pool slope.

Not a weekend for the faint hearted, Initially the 50mph high winds measured at the top near the cars, and slightly lower down on the ridge - a cold brisk 45mph. Conditions got worse as the day progressed within increasing wind speed and punishing gusts causing lots of turbulence.

I decided to give the stretched Wotzat model an airing. A bit of a challenge for its second flight, but I had confidence in its pedigree and having put 170g ballast in the fuz on the CoG, it was all or nothing. The model launched well and proved a success. It scooted around in the turbulent conditions with an air of grace. Loops were big and whilst the roll rate had been improved with greater control input from the first flight, I hadn’t got the aileron differential quite right with the rolls initially a little wobbly. Its second flight of the day was better and rolls much more axial having made a few tweaks to the transmitter settings, but there is still a little more tweaking required. I was really thrilled with its performance and only the bigger gusts of wind during turns had an effect on its composed posture. I was fairing a little worse by having to go down onto one knee to stay upright in the punishing conditions. I figure that for these conditions, more ballast would help the model and I have prepared a 300g slug to fit in the fuselage for next time we have a big blow, maybe a trip to the Great Orme, assuming I will still be able to stay on my feet in such windy conditions.

To compare its performance, I launched the smaller, 40” version into the extreme weather. 120g of lead ballast added first, and as before, the launch was uneventful. The smaller model was less effected by the turbulence and felt good on the slope. Not bad for a AUW of 500g!

I am now finally putting a little colour onto the new 50” model, it’s a shame to cover up the carbon, but I do like a nice colour scheme; In fact, the unpainted model was at times, difficult to see against lower reaches of the valley floor. The current weather isn’t conducive to painting the model though, not wanting to make a mess of the workshop, requiring a dry fairly calm day to warm up the paint, rush outside to put down the colour on the airframe and rush it back inside into the warmth to dry. Not ideal, but I don’t want to have to wait till the summer to finish all the paint jobs.

A week or so on, and a break in the very wet and windy conditions has allowed me to finish the painting which I am quite pleased with. I even got the underside paint to give me a carbon effect weave texture....
 

Now for more flying once the latest storm Dennis has died down............

Whilst I favoured the Small 40" wotzat over its big brother (50"), I now really like them both. The smaller one goes well and with a little ballast will take on most conditions just locked in and flying on rails. Some feedback suggests that the CG position is key to this. I must have got mine bang on the optimum CG position from the start, buty my good friend Mark, said he took him a little while to find hte CG sweet spot..

Its small size means its easy to transport and carry up the hills. My main flying site Parlick, requires a 20 - 30 minute walk to get to the place where we fly. A nice walk with fantastic views, so its easy to strap to my back pack, or even put it inside to carry up. The larger model Wotzat XL at 50" is not really that much bigger in comparison, but a little too big to put in the rucksack. However, now I have this model trimmed and dialled in and have made some ballast for it, it certainly generates conversation from the onlookers when its flying. Its fast and agile with 250g of ballast, indeed, Mark says he doesn't take his ballast out of his Wotzat XL.

So the detail so far:

The Target build / All Up Weight (AUW) or un-ballasted flying weight for the Wotzat models as follows:

Wotzat:               383g (13.5oz)   

Wotzat XL:          596g (21oz)

Both the Wotzat variants have now flown with additional weight / ballast with good results. Indeed, increased speed and that locked-in feeling on both was very noticeable.

For the Wotzat XL, I made up ballast by using 22mm copper pipe filled with lead. A 250g slug (50mm length of pipe) and 425g slug (100mm length of pipe).

By positioning a mini receiver to the rear of the wing bay allowed for the ballast to sit on the CG. Essentially under the forward wing bolt. With an extended wing bolt and a suitable hole drilled into the ballast, the ballast is locked in place once the wing is attached to the fuselage.

Photo clearly show the hole for the forward wing bolt to lock the ballast in place.

Wotzat XL:

Un-ballasted, the Wotzat XL comes out at around 596g (21 oz) giving a wing loading of 11 oz. ft². This offers a good speed range and a graceful and gently flight characteristic in light lift. Additional ballast has been trialled with marked results. It seems the optimum for wind speeds 15 – 20mph, 250g of ballast is appropriate, and this works well in higher wind speeds also. Adding additional ballast didn’t seem to make the model fly any faster, but the feel was very positive, locked-in as before and manoeuvres were big. In my opinion, the 250g ballast is what I lean towards, but I will be trialling the extra ballast further when the wind picks up more. It is all a compromise though, as you have to consider not only the flight performance, but also the landing weight and speed. Although, it did not cause a problem with landing when I tried it. This was also reflected in the feedback from a good friend who also had similar results having put similar amount of ballast in his own model.

Wotzat XL:         

AUW 596g (21oz)             Wing Loading 11 oz / ft²                              (No Ballast)

AUW 843 (29.7oz)            Wing Loading 15.6 oz / ft²                          (250g Ballast)     (15-20mph +)

AUW 1003g (35 oz)          Wing Loading 18 oz / ft²                            (425g Ballast)

Wotzat:

Whilst the Wotzat uses the same fuselage as the Wotzat XL, where it would be possible to fit the same amount of ballast as the XL, I have not tried this and do not intend to. In my opinion, this would be too much for the smaller model resulting in higher wing loading of around 16 or 20oz / ft² . Although 16oz / ft² is not unreasonable, but again, I have not tried this.

In the prototype Wotzat model, which has the initial lost foam fuselage without a canopy hatch, my ballasting options have been limited due to the fact that everything goes into the fuselage from under the wing seat. And, I have positioned a switch that restricts access, unless it is removed of course. But, I have been able to add ballast on the CG at the side of the switch in the form of 2 pieces of 10mm x 175mm copper pipe filled with lead (127g) which have been taped together (see photo above). The switch and some foam holds this nicely in place in the prototype fuz. There is no reason why you couldn’t do a similar weight (127g) with 22mm copper pipe and hold in place with the forward wing bolt like on the XL.

The model without ballast is quick and agile and in wind speeds of 10 - 15mph it still holds its own well with little down trim. However, when ballasted (127g) it quickly locks-in after launch and just eats up the sky, definitely a Pocket Rocket, and it actually holds its own with speed against the mid-ballasted XL even with the reduced wing loading. The smaller wing area and reduce chord keeps drag to a minimum.

 Wotzat:

AUW 383g (13.5  oz)        Wing Loading 9.6oz / ft²                             (No Ballast)

AUW 504g (17.8  oz)        Wing Loading 12.7oz / ft²                           (127g Ballast)

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Latest News : End of 2021....

It's now been quite some time since I put the original Wotzat and Wotzat XL together, and I find them both go-to models taking at least one of them out every time. A little ballast transforms their performance especially if there is a bit of a blow. Favouring the XL for higher wind conditions but both perform well.

These have generated a lot of interest and the last kits to go out ( one of each) were to a couple of guys down in Cornwall, one was a second Slope Dude build having built a Midge previously.

Anyway, I was recently approached by yet another guy who said that the two Wotzats were to take their maiden flights on St Agnes Head in Cornwall in the near future and he was to take a video.

Xmas festivities over and sure enough just into the New Year 2022, I was sent a link to the you tube video. Sadly the video has been removed from YouTube  but it looked a very blustery and cold day and the feedback from the new Wotzat owners were very complimentary, but you'll just have to take my word for it.........

Another link below to a Carbon version of the Watzat XL being flown on the hills of the Isle of Man.

https://www.youtube.com/watch?v=YLGSVX2-fsg

 See you Soon.

Whats new for 2022.

For some time now people have been asking if I have a design for fast 60" version of a flying wing, specifically for a 60" version of the Wotzat, and I hadn't, but it has been an idea that has been lurking in my list of concepts to explore.

My original Dude plank is a 60" wing, but is not particularly fast. nice to fly but slow in comparison to later models - room for improvement I think.

I'd also considered a 60" version of the Evolan previously, and I have cut a number of 60" wing core for other modellers to try but at the transposed thickness of the Evolan wing it's chord is too thick and a bit draggy, resulting in slower flying. A little more research is needed and maybe a different or at least a thinner section needs to be considered, which then leads to questions like, how will I manage the rigidity of a larger wing? Would I need a spar? What plan form shape would be best? all those type of design criteria need to be thought through.

Well, I've had a lot on my plate recently, working from home due to the pandemic which has been rather stressful with long hours and tight deadlines. On my down time, I've been catching up on making models for others and replacements models for me as I've sold some of my old models, that I haven't had much time to play with any new designs, although I have had many prompts from others - all well intended I might had. So having finally got a grip so to speak, I have now progressed........ and I've been busy with the CNC wing cutter and vac bag...........

So, what is it?

Well its not a Wotzat, although it does have its main roots in that camp, and it's not a stretched Evolan or a reworked Dude; I wanted something new.

A new wings section, new shape and a new fuselage - The new wing chord would not fit on the Wotzat fuz, it would fit on the Evolan fuz, which I did consider, if only to test the wing, but it didn't look right and it was just crying out for a new fuz - more aggressive looking. A couple of weeks and a number of carved lumps of foam later, I think I've got it about right and now it has a new lost foam fuselage..

Lost foam fuselage: Foam fuselage shape covered in epoxy glass cloth and then foam is melted out from within the epoxy glass. hence the term: "lost foam".

60" double carbon wing, Aileron and flap configuration which are switchable into different combinations of full elevon control, or aileron / flap but primarily configured with a 4 servo wing so I can utilise crow braking to slow the model down for those slope side landings. A lost foam epoxy glass fuselage and its all now done and painted, but not to cover all that carbon, I needed some of that on show - well, I've got to show it off.....

The first prototype has now had its maiden outing........ and I think I have created something rather special - but currently, it's a model with no name.

The test flight was on New Years eve ( 31 Dec 21) on Parlick, my local hill. A cold blustery day gusting over 30mph.

It flew straight off although my initial launch could have been better. After the first few seconds, a couple of clicks of trim and it was away building speed quickly, the speed equally matching that of the Wotzat if not a little quicker and without ballast for the first flight. having performed a number of dive tests I felt it needed a little more nose weight, but this is a personal thing to suit my flying style. However, the balance for its first flight at 18% of the mean chord was spot on for neutral pitch stability.

Its performance did not disappoint and it was soon bringing a smile to my face. Rolls were smooth and quite axial for the set up I'd dialled in, pitch was neutral in the dive and it responded well to light and aggressive stick inputs. Gentle inputs to a stall was a non-event, the model just bobbed and meandered about at full elevator.

I'd configured the crow brake with the same settings as my Dude ds model to start with, expecting to have to tweak this a lot to get it right. Setting up the original Dude crow brake was an experience that I'd rather not experience again..........    but no, a slight pitch down but otherwise it worked well.

No sooner had I landed from the first flight in the fading light of a winter afternoon, I tweaked the crow setting, giving a little more throw, I launched the model again just to perform a few circuits and there was further improvement in the crow braking effect and no bad tendencies and maintained roll authority, all was good.

See for yourself - enjoy

By the time I got back down the hill to my car, the light had faded to the point I needed headlights to navigate the country lanes on my way home.

I flew the new wing again on New Years day 2022 having made the hour half journey up at Nonts Sara, close to Saddleworth moor to meet up with a friend. A cold southerly wind occasionally gusting to 40mph, but I had expected higher winds, so this time I had loaded 250g of ballast in the fuz that I'd fabricated the night before. Again, I and the onlookers were impressed in how it cut through the turbulence and how well it flew, quite majestic but with agility when the sticks are stirred.

Whilst the model is a delight to fly, I think I can possibly squeeze more performance from it so I am now going make a bigger slug of ballast to try, but I am also going to explore the virtues of a new wing section before I decide on the final design. The half  dozen flights to date has given me enthusiasm to get out in the cold and get some good flying in and continue to optimise the new wing. I just cant wait to get it out on the slope again.

I hope to bring you some more video footage when I get my new camera, so here's hoping for a good wind and clear skies.

Watch this space for an update soon.

We are now nearing the end of January and we have had some pretty windy conditions lately, so I decided to make myself some heavier ballast to further test the new wing.

I made up a 360g slug of ballast to be inserted into the fuselage on the CoG, much like the Wotzat models. The ballast was made up from 21mm copper pipe filled with lead. However, due to the depth of the lost foam fuselage, I couldn't quite get this under the wing bolt mount without flattening the tube a little. (note to self, when I make the moulded fuselage it will have to be 5mm deeper to accommodate the ballast without modification).

As I said earlier, I first tried the 250g ballast on Nonts Sarah, up near Saddleworth moor, Greater Manchester, and it performed well in gusting 35 - 40 mph and I was really pleased with its performance, with the model holding its energy well.

Just a week ago, there was forecast of over 50mph westerly winds and a clear day, so armed with the new model complete with both sets of ballast I was off to Parlick, my local slope. The hike to the top took much longer than normal, due to the high wind speed and loosing my footing a few times and almost being blown into the shallow gullies. In fact, I nearly turned round and went home. Once at the top, the cloud came down over the hill, so by the time my flying buddy turned up, we just sat around in the cold, sheltering from the miserable windy and wet conditions behind the dry stone wall having a good catch up and sipping coffee.....

An hour or so later and almost ready to give up and call it a day, the first glimpse of sunshine and a view of the ground below us through the whispy cloud looked promising.

By the time the cloud had cleared we were shivering with the cold, but I had to give the new wing a go.

The clouds cleared quickly and the initial wind gusts measured around 41 mph, a passer by, later told us that he had measured the wind further up the hill at 58 mph.

The launch of the wing was relatively straight forward and it picked up speed quickly. I flew for best part of 40 minutes on the first flight with a huge smile on my face. Further flights were similar to the first, with the model locked-in and grooving around well.

I have put a short video together to give a flavour of the wing's performance in the high winds. Hope you like it:

Whilst I'm really happy with the new wing, I am considering trying a new wings section based on some research I've been doing. An experiment to compare performance before I finalise the design. I know, many of my firends have said why, it goes well already. Well, I'm always striving to get that better performance out of what I make, and this new wing section just seems like it might be even faster, so I've got to give it a try. Anyway, I've already cut the foam blanks, so I'll have to make the new wing now......

I will be pulling together a blog of the old and new build in good time with the results of the outcome of different wing sections..

See you soon.