Pre Lockdown Fly at L.H

By | November 4, 2020

Although the breeze was from the North East and unfriendly for gliders, it was good to get out and enjoy the really calm and clear air this morning. I decided to get out the thermal clothing and take my Riot up for a few circuits and try out my new Runcam2 camera for some area clips. Sidmouth Martin had made an early start but had not found any lift for his glider (sorry Martin, I cant remember the model name).  Exeter Bob arrived with his Vintage Models – Balsa Basics Cub for a maiden flight that went very well and I think the aerobatics were intentional. My Riot bumbled around the sky and recorded some aerial clips but I must remember which side the camera is pointing when I fly past our group. Duh!

Club Newsletter

By | November 2, 2020

Welcome to our first newsletter for a very long time. We thought that with winter looming and opportunities looking limited to meet up inside or out for a while that a Newsletter would help to keep everyone in touch. As John said in his covering email, the frequency of  issuing future newsletters will depend mainly on having something to report. We have had a couple of suggestions already, including highlights from our Facebook page, for a subsequent edition, so if anyone has any ideas or has anything to report from the building board, just drop Robert or John an email.

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David’s DR 420 test flights

By | October 9, 2020

By today’s standards my new ‘DR420’ is a blast from the past – balsa and ply, with spruce spars, full length flaperons, and mechanical mixing. She’s also the first model aircraft I’ve designed in over 40 years!

 

Maiden – test flights 1 & 2 – Black Hill

Her ‘maiden’ consisted of two flat field test glides and two 40 min test fights in a gusty 6-12 mph:

I didn’t touch the flap function for the first 20 mins just used aileron and elevator and struggled to get above 30-40 feet in less than ideal conditions. Applied about 30% down flap and she was 80 feet up quite quickly.

Stalling straight showed no tendency to drop a wing and recoveries were easy and with little loss of height. She did sometimes drop a wing in turns but usually not. I couldn’t establish exactly why but suspect that variations in wind speed caused the inconsistency. Mostly she flew pretty well for a first attempt. I found that:

  1. Flap function made more difference to airspeed than altitude and no constant elevator input was needed. With full up flap she does come down gradually but gains considerable energy. At full down flap she flies close to stall speed but with careful handling is still well behaved. 25-35% down flap was best for climbing.
  2. The aileron response is disappointingly slow even at high airspeed. Increasing aileron throw a bit made little difference. I couldn’t roll her past about 80 degrees no matter what I did and even that took ages and height was lost. I expected to be able to do quick 90 degree banks and turns using up elevator but she was having none of it. Most turns were fairly close to flat.
  3. When I flew her rudder/elevator the flight characteristics were almost identical (even with very little dihedral).
  4. Remarkably, flap position made no difference to aileron authority and no difference to the likelihood of dropping a wing. That’s good.
  5. She looked majestic in flight and sounded great in passing.

Next Day – test flights 3 & 4 – Chinkwell Tor

Beforehand – I increased and aileron throw AND the up-flap throw but decreased the down flap (bearing in mind that these are full length flaperons not separate control surfaces). Conditions were far better, a much steeper slope with a much stronger wind than yesterday gusting 7-17mph at eye level .

In these conditions she flew like a different bird possibly because of the overall higher airspeed but the increased aileron throw was obviously making a huge difference. Mostly I just tested her responses and watched for tip stalls:

1) Aileron response was good at a wide variety of airspeeds and was not affected by up or down flap input. She still won’t do a complete roll but did pretty fast 80 degree banked turns (both into wind and downwind) and half rolls from inverted were no problem. She even did a half-decent Cuban 8.

2) Up flap (now about 30 degrees) response was much stronger and looked identical to down elevator input (it had zero braking effect – quite the opposite!). It worked brilliantly when more penetration was needed but for bringing her down I guess the next thing to try is up flap and up elevator at the same time(???).

3) No sign of tip-stalling in any sort of turn or at any groundspeed (but probably the airspeed was constantly higher than yesterday).

4) Rudder response is great. She can be flown rudder/elevator and does great stall turns.

She really was a great pleasure to fly in these conditions. To anyone reading this who has not had a go at ‘designing your own’ I would say have a go.

With traditional spruce spars, her thin wings are pretty flexible and at speed she literally ‘wriggled’ her way though strong gusts – like a falcon rousing her feathers in flight – quite something to watch. In recoveries from failed manoeuvres I pulled far more G than intended which greatly increased my faith in the light balsa wing structure.

I hope to further improve the aileron response by increasing the flaperon differential (reduce the amount of down aileron). Mind you, if it doesn’t work I’m still a happy chappie. If I’d wanted an out-and-out aerobatic glider I would have designed her differently.

I guess that’ll be my next project.

David’s o/d glider build part 3

By | October 7, 2020

I um’d and ar’d over how to hinge the flaperons and eventually decide not to – to just let the film be the hinge. Multi-tasking was never my strong point so rather than try and wing-cover and hinge all in one go I decided to top-hinge the flaperons with a narrow strip of film first, I also covered the fuselage fairings before the whole wing:

Covering went well. The wing and tail undersides are dark blue. I was surprised to find that the cheap white Hobbyking went on better than the expensive dark blue Oracover. The winglets had 2 coats of sanding sealer, 2 of white enamel, and 2 of red:

The radio installation had been planned for from the outset so seeing it all fit – and the servo slide working –  was all very satisfying. Working out all the angles to achieve ‘more up than down’ was fun too:

The flaperon horns needed to sweep forward:

…and the elevator horn had to sweep backwards to be 90 degrees to the control cable:

I was pretty pleased with my first attempt at signwriting with Oracover after asking for advice on the Model Flying Forum.

Close-up of my first attempt at function mixing with a sliding servo:

The wing-mounted fuselage fairings hold the wing halves together:

Nose view:

 

 

 

 

Tail view:

 

 

 

 

 

And the finished model – the DR 420 –  ready for her first test flight. She balanced at 1/3 of her root chord without any ballast needed – pure luck!

 

Aero-Tow Events rescheduled

By | October 2, 2020

From John H.

Hi Everybody, here is a forwarded message from Rob Oats of the Okehampton Model Flying Club. It would seem the best option as suggested, is to just hold just one event at the most suitable venue Sunday the 11th Oct.

Good Morning Everyone,
Storm Alex has scuppered our plans for the aerotow at 18 Acre this
Sunday. We have next Sunday as the reserve, however this clashes with
the aerotow at Little Haldon. If the weather conditions favour Little
Haldon we will cancel. If weather conditions mean an aerotow in Exbourne
is more favourable than Little Haldon then we will consider holding the
event in Exbourne.

Regards,
Rob

1/3 scale K7 Build update from John

By | October 1, 2020

The K7 continues to grow slowly and the bags of laser cut parts are starting to diminish. After doing all I could to the fuselage I started on the tail end. The fin is integral to the fuselage so a rudder was next and fairly straightforward of balsa and 0.4. ply. A double horn was made from G10 2mm fibre board; very hard but files well. The closed loop cables will connect to this.

Lots of laser cut parts went together to construct the tail plane and this was covered in 0.4 ply as is the fin, all very strong but getting heavy! Elevators x 2 of built up structure are driven by 2 servos in the tail plane.

I made a mistake with the hinging and got the hinge line in the incorrect axis but hope to address this later.

As it is quite thick at the hinge line and the elevator needs to swivel rather than just move up and down.

I have now begun the first wing, will be in touch! (Robert: I look forward to seeing more pics of this stage John)

If anyone is subscribed to Scale Soaring UK, more pics of John build can be found. Click here –  UKJilles Smits 1/3 K7 Build

Now for Something Different

By | September 22, 2020

Stuart Chambers recently sent in a photo of this build by his No. 1 son. Does anyone recognise it? (of course Stuart knows the answer) Feel free to post your answer comment here or if more convenient over on our Facebook page.

Dartmoor National Park Bylaw on powered flight

By | September 22, 2020

We have had a couple of enquiries lately about whether powered flight is allowed on Dartmoor. The simple answer is No. As there may be visitors to our area intending to fly on Dartmoor and use our website to search out the best sites to soar, John asked for a statement to be added to our home page to reinforce our constitution and the advice given in our Dartmoor site guide.

“It is worth reminding club members and others visiting Dartmoor to fly RC that whilst non-powered flight is allowed, any form of powered flight whether electric or combustion is banned by the Nation Park Bylaws. Due to this importance this bylaw it is written into our constitution and  included into our guide on flying on Dartmoor.”

David’s o/d glider build part 2

By | September 12, 2020

An electric palm sander is a wonderful thing! If only I’d had one in the 70’s I could have filled the whole bungalow with balsa dust rather than just my little bedroom. Oh and the wonderful smell of cellulose dope… those were the days. And mixing my own diesel fuel… I regularly bought Amyl Nitrite and Ether over the counter in the chemist at just 15 years old! Anyway, back to the build…

After quite a lot of sanding:

 

 

 

 

 

Adding the fuselage fairings to the wing roots:

 

 

 

 

 

 

 

 

 

 

Then the wings had their final sand:

 

 

 

 

 

 

 

 

 

 

What you can’t quite see behind the winglets is, what was going to be the outer 4 cm of flaperon is now a short section of trailing edge with built-in washout. Will that prevent the nasty tip-stalls I’ve been warned about? We’ll have to wait and see.

To help achieve ‘more up than down’, the flaperons needed horns that were raked forwards. I couldn’t find any for sale so made my own using bits of plastic from an old bucket:

 

 

 

 

 

So here she is with her control surfaces pinned on just for the photo…

David’s o/d glider build part 1

By | September 7, 2020

I don’t know about you but I always like to start with the wings.

Using root and tip rib templates cut from some old aluminium I made a couple of ‘rib sandwiches’ using up bits of scrap 1/16th balsa and new ply for the root ribs. It’s a method I used ‘in the old days’, does anyone else still do this(?) I have no idea but I do think tapered wings are well worth the extra effort.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Building semi-symmetrical wings on a flat board required quite a bit of careful packing but before long the wing halves (one left and one right – hopefully) were mostly done minus the full length flaperons, winglets, and washout. Oh, and minus the fuselage fairings that would eventually cover each root (what?? – more on that later).

 

 

 

 

 

 

 

 

 

 

The fuselage was even more fun to build. Again, the plan was to use up lots of bits of scrap balsa (I hate waste) through creating a sort of ‘exoskeleton’ whereby the hard/curved outer skin of 1mm ply was fitted first then the thickness built up by adding strips of soft balsa internally. Curvy parts of the top & bottom were strip-built too.

 

 

 

 

I don’t have any kind of jig so I glued on the fuselage sides back-half-first making sure the fin was truly vertical before pulling the nose together a few days later.

 

 

 

 

 

 

 

 

 

 

Then the strip-work began in earnest until of all of my short 3/32, 1/8, and 3/16 scraps had gone.
Clothes pegs are great!

 

 

 

 

 

Whilst waiting for glue to dry I made up the sliding servo tray using a scrap of plastic cable trunking, a bit of old ali carpet strip, a bit of 1mm ply and off-cuts of light mahogany. Much more fun than transmitter programming(!), well, I think so anyway.

 

 

 

 

 

Underside view showing the internal strips and bottom strips going on:

 

 

 

 

 

At this point I decided to find out about setting up the flaperons and posed a couple of questions on the Model Flying forum which proved most informative (https://www.modelflying.co.uk/forums/postings.asp?th=167572&p=1). More news soon.
David