Chris Foss Phase Four and Phase 5

[Gary Binnie]

A couple of weeks ago I acquired a pair of Chris Foss slope gliders, a Phase Four and a Phase 5.

 

I have the plans for both and they were in the building queue but kept slipping down it!

 

The Phase Four is a 67" span, symmetrical wing section progression of the Phase 2 (there was an abandoned Phase 3 design according to Chris). The plan shows strip ailerons, there is another plan (that I don't have) that details flaps and ailerons with a mechanically coupled flap/elevator mix. This particular model had the split controls (or a variation of it) and an enlarged rudder with ventral fin. Reading a note on the plan the large rudder was revised in 1975 and the wing mount is also reversed (bolt at the front, dowel at the rear) so this model is either pre-1975 or built from the pre-1975 plan. The radio hatch was missing and some lead had punched a hole through the noseblock.

 

I'm not sure if it has ever flown, there were servo screw holes but no grass stains or other signs of use.

 

The Phase 5 (now available as the 5e in ARTF form) was unfinished, there were no fuselage servo mounts and the tailplanes were either missing or not built. It has been built true to the original plan with one aileron servo driving inner and outer ailerons through piano wire links and bellcranks. I have managed to free this up and get it working nicely, it would have been too much work with a risk of damage to convert it to a four servo wing (but I am doing that with the Phase Four).

 

Both models have been very well built and nicely covered in nylon, a skill I've not tried to learn (I know it wouldn't go well!!).

 

Some general photos:

 

Phase Four wing underside:

 

 

Fuselage:

 

 

Pre-1975 rudder and under fin, the other hole is for a 35 mHz aerial exit:

 

 

Fairly sound but missing the radio hatch:

 

 

Phase 5, minus tailplanes:

 

 

 

 

[Gary Binnie]

I worked on the Phase 5 first, it needed tailplanes and radio installation.

 

The all moving tailplanes are shaped from 3/8" balsa, I didn't have any sheet big enough so I laminated sheets of 3/16", have had to be resourceful in the lockdown.

 

The tailplane joiner and drive wires were rusted solid in to the plastic bushes and bellcrank, I used quite a lot of force and was in danger of breaking it but they wouldn't move. While I was gluing the tubes in I managed to CA one tailplane to the wires, doh!! I gripped the wire in my cordless drill chuck and turned it by hand, thankfully both wires eventually surrendered and I made a pair of shiny new ones.

 

The fuselage needed servo rails adding for the elevator/rudder servos. The wing looked visibly skewed when bolted on and it was quite a way out of alignment, I carefully broke out the wing bolt anchor nut and repositioned it (also upgrading from 2BA to M5 thread!).

 

The wooden elevator pushrod had been left overlength, all I had to do was trim it and add a bike spoke M2 threaded end, secured with CA and heatshrink.

 

The pull-pull rudder cables were installed but were quite rusty so I replaced them. It has a beam for the cables, what is odd is that the distance between clevis hole centres on the beam and rudder horn are not the same, this results in a slack cable. It has been built to the plan.

 

Installed servos and set the CG, one side of the wing was very much heavier than the other, no idea why. Have attached 30 g of lead to the opposite tip for the first flight.

 

The surface finish felt slightly rough, as if it needed de-nibbing, so it had a light rub of 400 grit all over. Some lumps and bumps from storage were filled with filler and non-shrinking dope mixed with some drops of Sadolin shed paint to darken it.

 

It's ready to fly now, I am working on some graphics for the wing and will probably add the painted canopy shown on the plan.

 

It's fair to say that both gliders were a bit grubby!:

 

 

Wing alignment, the aileron spar should be at 90° to the fuselage centreline which should also give equal measurements from the wing tips to the trailing edge of the rudder (fixed neutral)

 

 

Anchor nut visibly off centre, replaced this ply plate:

 

 

Rudder pull-pull beam, checked and cleaned, threadlock added to the 4BA nut:

 

 

Tailplane 'segments' with the grain direction matching the plan, I think this is for no other reason than making the planing and sanding easier though it possibly helps to prevent warps.

 

 

Tacking the tailplane wire metal tubes, making sure everything is square. It was at this stage that one tailplane got stuck to a wire.

 

 

Pretty much ready to fly, I think in this photo the tailplanes haven't been sanded to section.

 

 

   

[Gary Binnie]

Was going to leave sorting the Phase Four out until later but needed something to do during this chilly weather (not tempted to the flying field again, have been once).

 

It had a two-servo flap/aileron mechanism in the wing, I couldn't figure out quite how it was supposed to work and as it turned out the linkage was so stiff it would have probably burned out servos.

 

I was worried about damage during the surgery but it went very well. The piano wire running most of the span was chopped in to sections with a Dremel cut off wheel and then curled using two pliers. I attached some cable to the piano wire with heatshrink to have something to pull servo cable through (hoping that the holes in the ribs were big enough).

 

The 90° bell cranks were removed and their pivot bolts were cut down as I couldn't access them from the top, one nut refitted to secure them.

 

Luckily the holes in the ribs were just big enough for servo cable to be pulled through (very gently and slowly!).

 

Today I have been making servo mount plates and blanking unneeded pushrod holes.

 

This is the underside of the right wing, fuselage to the left, trailing edge up. The brown Paxolin link (one each side) operated the flaps (inboard ailerons), the spanwise piano wire was operated by a central aileron servo, when that moved the flaps moved in roll as well. Where washers were soldered on to the bellcrank links it was very stiff, possibly melted, I can't see that it ever worked as it was. No servos were fitted although there were screw holes.

 

 

 

I cut the piano wire into sections and attached thin electrical cable to the inboard end with heatshrink. Two brown Paxolin runners for the flap mixer can be seen.

 

 

At the outer end I curled the wire up and out of the wing using two pairs of pliers, the steel ruler is placed to protect the structure, I was hoping to spring the wire up and simply pull it out but it wasn't flexible enough.

 

 

The operating table! Have run out of gas in the shed so am allowed to work indoors.

 

 

All the mechanism removed, I had carefully cut out the Nylon from each servo bay which was very useful later.

 

 

More heatshrink used to attach the servo cable, it's shown near an end of the guide cable here but I attached it at the mid point so that if it fell off I would still have guide cable at both ends. I also tied knots in both ends of the guide cable to guard against pulling it out accidentally.

 

 

Luckily the holes in the ribs were just big enough to pull the servo cable through, phew!!

 

      

[Gary Binnie]

Carrying on with the wing servo prep for a bit.

 

I will mount the servos to hard balsa plates that will fit into the square holes left after cutting the covering away.

 

The main spar forms a ledge at the front of each bay, I added balsa strip around each bay to support the servo plates.

 

The covers for the flap links were missing so I made a pair.

 

Just waiting for servos now which will probably arrive tomorrow along with supplies for the A-10 build (I haven't abandoned it yet!)

 

Adding balsa ledges to the servo bays:

 

 

I realised that I could use the cut out pieces of covering to cut the servo mount plates to size and it will also help to partly disguise the conversion.

 

 

Cut slightly oversize, using the masking tape to double check, measure twice, cut once! I fixed the hole in the covering a bit better later.

 

 

Perfect fit! I blanked the old pushrod holes while I was at it.

 

 

One thing that I noticed was all the control horns were bent, leaning to one side. I think the wing was probably stored flat, lower side down and the weight resting on the control horns has caused them to deform over time.

 

 

I remembered a trick from school, thermoplastic can be reset with heat. I made a fire blanket from cereal packet and applied my heat gun, pushing the horns straight with a block. Worked well, the horns are too long, I will trim them once I've worked out the best gearing.

 

 

 

 

 

[Gary Binnie]

Another job was to make a new radio hatch.

 

I had a mental block on how to do it for quite a while, in the end I pretty much followed the plan.

 

It's made up from 1/2" balsa sheet, again I didn't have any scraps large enough so I had to change the grain direction of the top part and add it in sections (instead of two pieces).

 

Back marking the dowel holes accurately was a little bit tricky.

 

It looked very rough before carving and I wasn't convinced it was going to turn out well but it did, yay!!

 

To hide the very new balsa colour I will paint on the canopy shown on the plan.

 

Two 1/2" balsa sides with an 1/8" wing seat (not on the plan, mainly there to hold the sides in the right place).

 

 

Adding the top sections, grain crossways (supposed to be lengthways), just makes carving/sanding a bit trickier. The sheet at the front is acting as a wedge to compress all the glue joints (wing is bolted down).

 

 

I wasn't convinced it was going to turn into a thing of beauty but it did!

 

 

The majority of the carving and rough sanding only took about 20 minutes. I fitted the hatch to the fuselage for final sanding, the wing bolt was used to clamp it, the brown wood is very old 1/16" ply. The fuselage was protected with masking tape.

 

 

I had made holes for a radio switch then later realised it would be better to have it in the black area of the canopy, I marked the canopy lines and happily it is ok where it is. The hole for the original power switch can be seen further forward, I plugged this with balsa and cocktail sticks in the screw holes.

 

[Jonathan M]

13 hours ago, Gary Binnie said:

Rudder pull-pull beam, checked and cleaned, threadlock added to the 4BA nut:

 

Fascinating refurbs.

 

What is the forward-moving pushrod on the rudder servo for?  Tow-hook release?

   

 

[GrumpyGnome]

looks like that goes to the servo to actuate the rudder cables...

[Gary Binnie]

Yes, that's it. Can also see here the new wing bolt ply plate which I doubled in thickness so the prongs from a 'T' nut could bite into it, the original 'T' nut was inverted (prongs pointing down) and hopefully epoxied to the bottom of the plate.

 

This is the Phase 5 as drawn on the plan, the Phase Four has a snake which I was going to replace but that is also original to the plan,when I looked closer it is a posh snake with wire insert. 

 

The space between the beam support and the thick ply half former in front is for ballast, would need some kind of lid or catch arrangement to stop it falling out when inverted.

 

 

 

[Jonathan M]

2 hours ago, GrumpyGnome said:

looks like that goes to the servo to actuate the rudder cables...

 

Durr! [slaps own forehead!] 

[Gary Binnie]

Phase Four:

 

Had a very full day working on it and feel proper worn out!

 

Wing servos arrived so I could push on. After checking they all worked the plugs were cut off the aileron servos (warranty gone) and they were soldered to the extension cables and insulated with heat shrink. At the inboard ends of the extensions I fitted crimped terminal and plugs (can detail this if anyone would like to know how to do it).

 

The aileron servos clashed slightly with the remnants of the bellcrank system so it had to be carefully removed.

 

The flap servos were much quicker to install as they didn't need extensions and there was no clash with any structure. The servos were connected to their surfaces using wire links with a double Z bend.

 

Just some tidying left to do then this model will be added to the pile waiting for their first flights at the slope.

 

1. To save cutting bigger holes in the ribs I took the plug off the flap servos and threaded the three individual wires through taped to the extension for the aileron servos then refitted the plug.

 

 

2. The servos were glued directly to the plates, this is normal practice for F5J glider tip aileron servos and is plenty strong enough. Sub trim was used to get the horns at 90° to the servo to avoid any differential problems.

 

 

3. Servo plates were taped in after threading through a double Z bend piano wire link, have left the horns over length at the moment but I think the gearing is about right.

 

 

4. Thought I would never get to this stage!

 

 

 

5. C of G and lateral balance to set/check, the wing and tailplane are not quite square (I have a cunning plan to fix it) and some decoration to be added.

 

 

 

 

 

[Gary Binnie]

Set the C of G on the Phase Four today, meant to weigh it and check the lateral balance but forgot to do either! Stuck a masking tape note on the wing to remind me.

 

Programmed the radio including fail-safe.

 

Masked the canopy area of both gliders, hoping that it will warm up a bit to spray in the garden.

 

 

 

[Phil Cooke]

I do like the Phase 5 - lovely renovation - great to see the incremental improvements made that got us to the thoroughbed standard that was the Phase 6.

Edited April 16, 2021 by Phil Cooke

[Peter Garsden]

I built a Phase 5 from plans in about 1975. Covered it in black Solarfilm with silver trim. Flew really well. Very aerobatic. My favourite plane at the time. Fond memories. Ah.....

[Gary Binnie]

I have a Phase 6 as well, sport wing version. I'm a fan of Chris's designs, both glider and power. I have the plans for the Phase One which looks like a challenging build and will require a re-mortgage for the wood!

 

I'm waiting for black satin paint and the temperature to climb a bit so I may as well come clean and list all the Foss types I've ever owned and/or built, in chronological order (roughly):

 

1. Two channel Middle Phase, learned RC with this, recently replaced with a new build with both wings.

 

 

2. Centi-Phase

 

Was given a wooden Centi-Phase that met its end at the bottom of a slope when the lift died (have no photos of that one). Acquired a finished model with Graupner spoilers (Orange fuselage) then an NIB kit (foam wings) from an emigrating airline pilot (white fuselage). Some time later I got hold of an original short kit rib and accessory set to make built-up sheeted wings, much lighter and transforms the glider. More recently I have built a wooden fuselage so I will eventually have all three versions (glass fuse/foam wings, glass fuse/built-up wings and all wooden).

 

 

 

 

 

3. Wots-Wot

 

Acquired half-built about the same time as the first Cent-Phase (mid-1990s ish), not finished until about 2002. Glassed all over, lower wing is straight, upper wing is swept back. ASP 61 power.

 

 

4. Hi-Phase

 

Enormous three channel glider with a built-up wing (foam/veneer was available later) and a modified Centi-Phase fuselage (new balsa fin added with T tail). Later a dedicated fibreglass fuselage was available (taller, more swept back fin and revised canopy hatch cut-out to remove stress points). I built this model from a very poor condition fuselage which was possibly a copy and built the rest from plans.

 

 

5. Multi-Phase:

 

Built from plans with foam wings. Did not have a charmed life and was eventually lost to radio failure. I have an uber rare kit for the Multi-Phase 100.

 

 

6. Phase Lift:

 

Vintage thermal soarer bought built with equally vintage radio installed, it has all the original mechanical mixers for the 'trimmable trailing edge' and coupled rudder to aileron. Wing tips are backwards, very nice build but the tissue is quite brittle so it doesn't fly very often.

 

 

7. Phase 6, kit build, glassed all over. 

 

 

8. Xtra Wot.

 

Sometimes I like to be a hooligan! Kit bought from SMC in 2014, finished quite quickly and then sat for a long time until I could find a 100% fuel proof finish. painted with two-pack (forced air breathing in a spray booth).  OS 120AX power, two-seat conversion.

 

 

[Gary Binnie]

Had a nice ride on my motorbike to my nearest Halfords, their satin black spray has good reviews so I was hopeful of a good result. Got home and finished off the masking using newspaper and bin liners to prevent overspray and went for it in the garden. Temperature was just warm enough for spraying and no flies about so things went smoothly.

 

Once the black areas had had three coats (15 minutes between each) I moved the parts indoors and turned the central heating up to promote drying. One small area lifted with the masking tape but otherwise I'm very pleased with how it's turned out.

 

Tomorrow should be final fettling and weighing to discover what the wing loadings are then have to wait for the wind to change from East to West and throw them off a big hill!

 

1. Parts fully masked and painted, the whole Phase Four wing had to be masked just for the small area at the centre section. It's at this stage that I worry about any areas I might have left unmasked, as it turned out there was one tiny area of overspray that I just scraped off with the edge of a scalpel blade.

 

 

2. Swiftly moved in to the house to warm up and cure, no bubbling or other reactions and a first for me, no runs, pinholes or fish eyes!!

 

 

3, 4 and 5. I de-masked before the paint edges fully hardened which went very well apart from one small area that lifted on the P5. I fixed this by applying more masking tape and spraying in to a yoghurt pot and then dabbing with a very small paint brush.

 

 

 

[Gary Binnie]

Lovely day to work in the garden, both gliders are pretty much ready to fly. I'll do a post for each to avoid confusing myself (easily done!).

 

Phase Four:

1. Labelled all the wing servo leads.
2. Rechecked the C of G, slightly nose heavy so removed some lead, C of G at 4 inches/103 mm per the plan.
3. Lateral balance good, no weight needed on either tip.
4. Something that had become increasingly annoying was the wing bolt nut spinning under its plate, made a couple of new ply plates (one spare) as the old wood didn't look very happy and CA'd the nuts to the plates. It's a similar arrangement to the Phase  but I think that uses a spiked T nut.
5. Secured the receiver with Velcro and glued in guide tubes for the aerials.

Weight is 1,165 grammes or 41 ounces/2.5 lb, wing loading is a very low 10 oz/sq/ft. I think some optional ballast would be a good idea.

 

All it needs now is some wing seating tape as there is a gap on both sides and the wing can rock slightly, by adding more to one side than the other it will straighten the wing up to align with the tailplane (my cunning plan mentioned earlier!!).

 

1. Labelling wing servo plugs.

 

 

2. Ye olde wing mount plate with spinning nut.

 

 

3. Not sure this is the right arrangement, it's different to the plan but it does work.

 

 

4. New plates made and nuts CA'd to them.

 

 

5. Power switch disguised in the canopy area, almost as if it was planned!

 

 

6. Homemade graphics.

 

 

 

7. Ready to go.

 

[Gary Binnie]

Phase 5:

1. Rechecked C of G and lateral balance, C of G is 88 mm/3.5 inches per the plan.
2. Something I had noticed earlier was a mismatch between the inboard and outboard ailerons on the right wing only, they should have been carved and sanded together because of the changing wing section toward the tip so I think the outer aileron has warped, possibly by being loaded up in storage. I've steamed the outboard aileron ('tis doped but the ends are not) and clamped it, hopefully it will recover its original shape.

Weight is 1,376 grammes/48.5 ounces or pretty much exactly 3 lb. The wing loading is also low at 12.3 oz/sq/ft. Will look at ballast for it and some kind of retaining method (not shown on the plan).

 

Going to have a full car next time I go to the slope, these two and a Multiplex Akro, Cortina and Twist all need maiden voyages.

 

1. ACME lateral balance checking device, round pencil taped on as both gliders are flat bottomed and don't easily tip to one side or the other.

 

 

2. Mismatch of the wing surfaces, only on the right side.

 

 

4. Steamed, clamped at the tip and loaded with some weight (control link disconnected), hopefully this will do the trick.

 

 

5. Homemade graphics

 

 

6. Ready to go.

 

[Jonathan M]

Neat and very efficient refurb jobs on both Phases, and the home-brew graphics finish them off perfectly!

[Gary Binnie]

Cheers Jonathan, I'm very pleased with how they've turned out.

 

Was toying with stripes on the wing and tail upper surfaces but the canopies will help very much with orientation. Was also worried that there might have been a paint reaction (I had a minor one early on with dope) then I would have really been in trouble! 

 

The graphics do a secondary job of distracting the eye from lumps, bumps and stains that couldn't easily be fixed. I have no idea what the finish is on the P5 ailerons and rudder, it's a sort of yellow/brown transparent stain, reminds me of Humbrol fuel proofer from about 45 years ago.

 

The aileron straightening trick seems to be working, I'll leave the weights on for a bit longer.

[Jonathan M]

If you find you need a bit more help with visibility, while avoiding paint reaction issues, there's always the option of some brightly-coloured self-adhesive Oratrim (or similar film product) for added vitamins...!

[Gary Binnie]

Spent yesterday flying F5J practise but I took the Phases to show my flying buddy with thoughts of test gliding them.

 

The wing loadings are quite low for slopers so I was fairly happy that they would be ok to test glide at a flat field (and I'm glad I did!).

 

I had way too much elevator travel on the Phase Four and it was very twitchy in pitch, my buddy launched it for me so I was on the sticks ready for  for corrections either way. I reduced the throw by half and it was much better. I do programme several flight modes with reduced travels so that I can calm it down at the slope if there has been no test gliding.

 

Chris usually gives the control throws on the plan and he had! 3/4 inch total elevator travel, the note was by the elevator on the plan and not near the rudder/aft end of the fuselage where he usually puts it, as I didn't build the tailplane/elevator I had missed it.

 

The Phase 5 was much better behaved, it appeared to have not enough elevator authority to flare fully for landing but I think that was just due to the low airspeed. Elevator (all moving tail) travel is on the plan in the usual place, 3/8 inch up and down at the trailing edge.

 

Just need the wind direction to change now.

 

F5J practise wasn't easy, chilly breeze knocking the thermals over and I deliberately used my heaviest model (built-in ballast!).

 

      Cheers

 

           Gary    

 

 

Little and large!

 

[GrumpyGnome]

Nice job on those!

What's the little glider with the Xplorer?

GG 

[Gary Binnie]

Cheers. The little glider is a Kyosho Swing which I think is pretty much the same as a Great Planes Fling, possibly built in a different factory.

 

The oldest photo I have of it is January 2007 so I probably bought it in 2006.

 

[GrumpyGnome]

Cheers Gary - very nice!

 

GG

[Mike Chantler]

Lovely looking Phase models :). 

I also inherited a very old and nicely built P4 with the full snap flap type mechanical linkages, and like you, replaced with servos. Despite the fully symmetrical section it flies in quite light conditions and I much prefer it to my own P6. It's lovely and slow, but fully aerobatic ? Very relaxed flying ? ? I'm sure you will enjoy.