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Bowlus Super Albatross

Let us all watch your new project progress.
User avatar
Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Bowlus Super Albatross

Post by Peter Balcombe »

A bit more work done on the RH wing in preparation for applying the wing skins.
In addition to sanding the various areas of wood flush, balsa doublers have been fitted just behind the main spar web at root & tip to support the skins.
An 1/8” Sq spruce spar has also been let into position 30.9mm behind the spar web in the brake area to support the upper skin in this area. (The plan shows this support spar, but no slots in the ribs. I’m sure this will be sorted in further kits).
Also shown below is the aluminium wing retention tongue between the root ribs. This needs to be fitted before the upper root skin is fitted.

As can be seen below, the upper D box skin has also now been fitted. (Possible using 2 lengths from a 4ft sheet)
Brake area skin support spar
Brake area skin support spar
Wing retention tongue
Wing retention tongue

I have also fitted balsa support blocks at the aileron hinge poisons & epoxied Dubro#257 hinges to these prior to fitting the skin strips over them. (Brass hinge split pins used during fixing, but now removed until the aileron has been separated from the wing).
Aileron hinge fitting
Aileron hinge fitting
User avatar
Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Bowlus Super Albatross

Post by Peter Balcombe »

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After a few weeks off to visit family across the pond, I’m back in harness.
First job was to complete the upper skinning on the RH wing (apart from rib & brake vane caps).
With this now done, it’s time to turn the wing over & remove all of the building tabs ;)
User avatar
Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Bowlus Super Albatross

Post by Peter Balcombe »

A little diversion from finishing off building the first wing to make the tow release mechanism……

This release is based on a short length of 15mm Aluminium U channel section bolted onto the rear of the double thickness front former, with the channel forming 3 sides of a box on the rear side.
The tow loop is fed up into the channel from the bottom of the fuselage, guided by 2 wedges, between two 1/8” steel pins - above which slides an 1/8” steel servo operated cross pin.
Small hardwood blocks support the channel at the 2 attachment bolting points & a third block (mounted on the rear) carries the cross pin running in a brass bearing tube.
Hopefully the attached shots show how it works (angled end of channel at bottom, bearing tube block at rear. Ignore the unsupported hole in Ali 🤫).
View from left side
View from left side
View from front
View from front
View from bottom
View from bottom
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Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Bowlus Super Albatross

Post by Peter Balcombe »

1st wing now nearly ready for covering - just requires LE sanding to profile.
(Blue foam blocks attached to root rib in photo are to protect the wing retention tab.)
The 3D printed tip moulding was attached using 2 wire pegs epoxied into the tip moulding & balsa reinforcement blocks fitted inside the tip rib.
The aileron was cut from the wing once the main skin area had been fitted - starting from wide hinge gap on bottom surface & marking top rear of hinge spar for final cut in top skins.
M3 clevises & aileron pushrod used. Hatch fitted in lower rib bay & both top & bottom of aileron servo rib bay skinned.

Top surface skinned - brakes In
Top surface skinned - brakes In
Top surface - brakes Out
Top surface - brakes Out
Lower surface
Lower surface
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Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Bowlus Super Albatross

Post by Peter Balcombe »

2nd wing now at same state as the first, with just the final LE profiling to be completed prior to covering.
The 3D printed wing tips were fitted using 2 short 16swg rods epoxied into the moulded tip holes & then corresponding holes drilled into the tip ribs. In retrospect I should have fitted balsa support blocks on the inside of the tip ribs before skinning this area ;)
The tips were about 6mm shorter in chord than the tip rib, so I fitted centrally & sanded back LE & TE to fair in.
3D tip fitted
3D tip fitted

The aileron servo bays have been skinned top & bottom, with servo hatches & pushrod exits provided in the underside.

Aileron servo linkage
Aileron servo linkage

The fuselage pod planking is now complete apart from the area around the tail boom attachment. This has been given an initial sand back & faired in with the 3D printed nose cone.
With the cockpit fairing removed, the 2 temporary former bracing bars can be removed & easy internal access gained to cockpit & forward fuselage, plus the rudder servo area behind the cockpit.
The underside planking was initially extended over the wheel area & then a wheel aperture removed once the planking had been sanded to a curved profile.
Note that the laminated skid has yet to be fixed to the mount. Access to the tow release can be seen just behind the nose cone.

Wheel aperture
Wheel aperture
Tow release position
Tow release position
Pod nearly planked
Pod nearly planked

Next job is to fettle the wing roots to achieve a good fit along the complete 22” chord length prior to fitting the tail boom & completing the fuselage planking.
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Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Bowlus Super Albatross

Post by Peter Balcombe »

Pilots seat made up & tried for size in the “Office” :D
I laminated the seat pan from 2off 0.4mm ply sheet instead of the recommended single piece of 0.8mm ply, but either way would work. My reasoning was to more easily achieve the sharp bend at the rear of the curved pan, but pre-soak8ng the 0.8mm with hot water would probably do the same thing.
Seat assembly with loose backrest
Seat assembly with loose backrest
Sat in place
Sat in place
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Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Bowlus Super Albatross

Post by Peter Balcombe »

Tail boom now fixed in place after checking that the stabiliser & wing joiners were parallel - eyeing from one to the other makes this easy to do. Once the boom is in place & aligned, the fixing pin hole can be drilled through, dowel fitted & everything alignment re-checked before the epoxy cures. I used a short length of 1/4” carbon shaft length for the dowel.
Boom fixing dowel
Boom fixing dowel

The rudder closed-loop cables take a straight path from the forward end of their tubes to the servo, mounted an an angle just behind the pilot’s seat. However, this path goes through cutouts in the centre section brace plate & access to the rear part of this would be a challenge once the upper fuselage planking is in place.
Hence I decided that the C/L cables are better fitted & terminated before the fuselage planking prevents access.
There is limited space at the rear of the boom between C/L tube exit and the rudder horn, so I cut back the tubes as far as possible & terminated the C/L cables in loops which secure to the rudder using M2 bolts - allowing the rudder to be removed, but allowing full rudder movement when connected.
Note that an extended servo arm (made from Epoxy board) has been bolted to the top of a normal servo arm to give a 40mm attachment spacing as for the rudder horn.
Forward C/L tube exits
Forward C/L tube exits
Rudder servo & extended arm
Rudder servo & extended arm
Rudder attachment
Rudder attachment
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Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Bowlus Super Albatross

Post by Peter Balcombe »

With the upper fuselage pod planking completed & 3D printed tail cone pieces fitted, it’s time for another check assembly & balance to see how much lead can be safely put into the nose.
The plan shows the balance point to be 196mm behind the LE at the root.

With the wings pulled back 15mm or so from the fuselage, the model can be check balanced using a couple of hooks locating in the fuselage root ribs at 196mm from the LE (approx. the front edge of the wing retainer tabs).
This showed that approx 1.75Kg was needed in the front fuselage former bay to achieve balance,
After making an allowance for the planned 2off NiMh packs & pilot etc at approx. 1Kg then probably 0.4-0.5Kg can be safely put up front.
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User avatar
Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Bowlus Super Albatross

Post by Peter Balcombe »

Whilst finishing off the elevator/rudder skins/rib capping & sorting out the removeable canopy area of the fuselage, I now realise that the canopy glazing hoop C4 should have been fitted prior to finishing off the canopy area planking. The planking needs to go right up to C4 to avoid a step at the front & enable the surface profile to curve all the way up to the canopy.
Looking closely at the drawing & photographs of the full size replica, the canopy appears to need to be fitted into a narrow slot made in the planking around the edge of C4, thus effectively using C4 as a hidden internal locator.

The pic below shows the amended build, with extra balsa sheet fitted to the top of C5 & shaped to fit up against the outer edge of C4 prior to sanding to give a continuous curved profile up to the top of C4.
A slot will now need to be cut around the outer edge of C4 to allow the canopy glazing to sit in in due course.
(My backup plan is to fit a further hoop to the top of C4, but that would then be visible through the glazing!)

Last task before glassing the fuselage (including canopy section) is to fit registration pins & retention magnets to the canopy frame.
Updated canopy frame
Updated canopy frame
User avatar
Peter Balcombe
Posts: 1399
Joined: 18 Mar 2015, 10:13
Location: Clevedon, North Somerset, U.K.

Re: Bowlus Super Albatross

Post by Peter Balcombe »

Well, the canopy preparation wasn't as bad as I expected 😀
I first ran a scalpel around the the outside of the glazing frame C4 & then carefully made a 2nd cut 3mm further out. Removing the 3mm wide strip of balsa & cleaning out the slot with the edge of a needle file was straightforward, leaving a slot as below.
Glazing slot
Glazing slot

The canopy glazing moulding was then carefully cut to size, steadily taking parallel strips off the bottom until the glazing rested on the top frame hoop with the glazing sitting in the slot all the way around.
Then the rear of the glazing was cut to size with the canopy frame in situ.
I’m pleased with the result as long as I can keep the slot as clear during fuselage glassing.
It should then be a simple matter of sitting the glazing in place once the slot has been primed with canopy glue.
Glazing sat in place
Glazing sat in place
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