Yet Another Prototype Slope Soarer

Pike the Slope Soarer

Following the successful maiden flight at Leckhampton yesterday I thought I should take a couple of pictures of it whilst it is unscathed… Pike started out as an experiment to make half a wing using balsa covered foam to compare weights with the glass fibre wings. This showed a 50% reduction in weight for the equivalent wing area in glass fibre. I also wanted a thinner wing section to help with the speed range to the extent that the aileron servos are mounted to the wing core within the fuselage and using a torsion bars. To test the wing I built a crude balsa box fuselage with V tail and painted the whole lot in clear acrylic varnish.

The initial maiden was carried out at the field where it performed in a similar fashion to the Skua being a light wing loading (9.8oz /sq foot). for maiden at Leckhampton, Mel launched it and to my surprise it was easy to fly and more stable that the Skua which maybe due to the bigger wing span, 1.87m against 1.5m for the Skua. The only real problem was the crow braking which caused the nose to climb, more down aileron needed.

What next, slicker stronger wings, sleeker fuselage…

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RE8 ‘It Flies’

The decision to build a RE8 is from recent information from Belgium confirming my Great Uncle died whilst flying an RE8 in Belgium at the end of the First World War, which was a surprise as he normally flew Bristol Fighters.

This first model is small with a 37″ wingspan and 25″ long and a bit heavy, it is intended to test its ability to fly, as they had a reputation of being a ‘Killer’ even models are said to be difficult to fly. The plan is to build a larger version next winter using wood and cloth. I used the attached drawing plus a specification of the original planes to design the model using balsa, aluminium and foamboard for the main wings.

The maiden flight was a surprise as it took off cleanly and was stable with no trim required… however, like the fullsize aircraft it does not like too much roll as it stalls the wings and drops into a dive. but flown in gentle circuits it is stable together with a nice glide for landing. It did manage 1 loop, but was not happy.

Drawing_RE8

RE8_1

RE8_2

Roll on the weekend for another fly

Riot goes FPV

Following the development of a new fuselage over the winter and the addition of a camera and transmitter, the Riot has now gained a Eagle Tree Vector control unit and GPS/compass. So for those interested in this technology and to demonstrate my inability to fly in straight lines I have attached some data outputs from the Vector. The circling on the right of the Google screen dump is the plane in loiter mode whilst I took off my head set (cardboard box with LCD screen fitted) and put on my glasses  so I could land, a little more practice is required before landing in FPV…

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Note: all data in English Units

A key learning point from the day was the criticality of wing incidence, my Riot was not the easiest of plane to fly which I thought was due to the CoG being 15mm further back than the maximum recommended in the in the Riot manual. So I moved this forward for the first flight of the day and it made negligible difference, so I tried packing the trailing edge, this made it worse still, so I put the CoG back to my original setting and packed the leading edge of the wings by 4mm and this transformed the characteristics for the better.

BFG (Big Friendly Glider)

For those who do a spot of slope soaring, these are my initial pictures of my latest experiment – 3.75m glider using glassfibre wings and balsa for rest of the construction.  If it doesn’t fly, it will be a big crash…

the BFG development is now ready to test, all we want is a nice westerly and a visit to Pole Cottage…

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Sorry about the orientation of pictures, rotate does not seem to work on the blog

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‘Thermolite’ Slope Soarer (with a…)

Following on from the ‘Flying Brick’ lessons learned which is ready for the right conditions i.e. lots of lift… I had a rethink on my second prototype requiring it to be significantly lighter and have a motor fitted (hidden when soaring) to enable it to be flown at the field assuming it does fly.

The key differences to try and meet the lighter weight is; a carbon fibre boom and moving tail as the back end of the Flying Brick is the primary contributor to the overall weight as the balance weight had a ratio of 2.8:1.

To improve the build finish and help keep the weight the wing skins are made as two separate pieces using aluminium moulds then bonded together with spares glued in. The fuselage mould is mage from 2” aluminium tube; shaped then split on the vertical axis.

I have attached a couple of initial photographs; one of the moulds and the other of the part assembled components. I will be providing updates as I get a little further through the build.

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We are now getting closer to painting, need to fit the wing servos and tips… The controls for the moving tail and rudder are complete ready to fit after spraying, but what colour(s) shall I use?

Thermolite nearly ready to paint

The final painting and assembly is complete with an ready to fly weight of 1.4kg a touch heavier than wanted and may push the motor to the limit when field flying, that’s assuming it flies… I used base coat metallic silver as it thin and should be lighter that standard gloss cellulose.

Pre maiden flight
Pre maiden flight

Assuming it flies at the field and is not destroyed, the next step will be to replace the prop spinner with  a glass fibre nose for soaring.

‘Flying Brick’ Slope Soarer

Earlier this year I tried a new flying change – slope soaring using a Spectre flying wing. Following this initial experience, I decided I wanted to build my own conventional type of glider and started looking at kits and glass/carbon fibre planes. However, having spent many years messing with, building and racing cars, I thought it may be a interesting idea to try some of the techniques and methods used in developing and building car bodywork, hence this design and build exercise.

I started by researching designs using information from various sources including:
http://www.phoenixmp.com/articles/slope.htm
http://www.rc-soar.com/tech/perfanal.htm
http://charlesriverrc.org/articles.htm
http://www.flyingobject.com/

My first activities were to develop a design spec based on the phoenixmp article, full size wing drawing and produce a short piece of wing section from a split aluminium sheet mould to understand the weight and strength. The spec is attached to this blog, where ‘1850 Mk1’ is the current build which started with a target 12oz / ft2 wing loading (I was dreaming…) and ended up at 21oz to achieve the balance, hence the flying brick. The ‘1850 Mk2’ worksheet shows my initial thoughts for my next build with the primary focus on reducing weight.

Design Spec v0.2

To give an idea of the build, I have included some photos showing the wing moulds and views of the model.

Wing mould

Unpainted model

Radio and V Tail Servos

Prototype ready for flight
Prototype ready for flight

Key points from this initial prototype:
– the tail and back end of the fuselage needs to be lighter;
– extend the nose length to reduce the ballast up front;
– reduce the size of the ‘V’ as this was based on the suggested ratio, hence change in ‘V’ tail spec;
– change the wing build method from two single sheets of 200g Woven Roving layed-up across both halves of the mould and folded over the spares, to producing two separate halves then join together over the spares;
– Use a metallic silver paint base coat instead of normal cellulose to reduce weight;
– reduce the diameter of the fuselage where the back used a split and tapered 1 1/4 “ waste pipe and rolled lemonade bottle for the front, this will necessitate putting the ‘V’ tail servos in tandem;
– Stiffen wing control surfaces.

The maiden flight was carried out at Burton Dassett with a westerly wind, not the ideal direction, limited lift and turbulent. flew my wing first and struggled with lift at times as it is 50% over the recommended weight, but in for a penny, in for a pound decided to try the brick. Before Robert threw it off the hill we checked the controls surfaces and put on a few degrees of flap. Much to my amazement it flew straight and level but did struggle to make height, eventually after a few turns landing on the slope. The second flight was better but still struggled to make height particularly on the turns, its 2.165kg weight was showing. It should be easier to fly with a more stable lift, Great Orme beacons or at least a true SW wind at Burton Dassett. In the meantime, build Mk2.

Not so Ultimate BiPlane

It has been over 40 years since I last scratch built a plane and then it was balsa and tissue, and it crashed… So this time not wanting to make life easy, I printed a A4 version of a foam plane, scaled the general proportions and used a flight test method of construction. The general specification:

Wing span: 840mm
Target weight: 1400gm
Wing area circa: 35dm2
Motor: 3536/1100/7 – 470watts
ESC: 60A

To give you an idea of the current build state, I have (I think) attached a couple of photos. During the ongoing build, I will provide updates, but do not intend to maiden it until the weather is better and I have mastered the RIOT!!!

Wing construction
Wing construction

Main components

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Partial painted components

Hi all, now for a quick update; as can be seen from the pictures, the BiPlane is basically finished, however I do want to replace the wheels as I’m not happy with the current foam board version. I am trying a bit of an experiment with the sprung under carriage to help with landings on rougher ground (not that I would miss the landing strip).

At the start of this project, I had some target design figures with the key target being weight which has come in at 1.29kg fully loaded with battery. The result of this shows in its ability to not only lift itself vertically, but also pulls my arm up… All we need now is better weather so I can practice with the Riot before risking this plane.

BiPlane front quarter view
BiPlane front quarter view

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OK… The first maiden flight lasted a couple of seconds… the last maiden flight was a few seconds longer as shown in this clip

All is not lost, the parts have evolved into the FlighTest Spitfire, a little over powered, but still within the FT design weight at 830 grams including battery

The evolution of the not so Ultimate Bi-Plane - Reborn
The evolution of the not so Ultimate Bi-Plane – Reborn