Percival Vega Gull

[Outrunner]

Looks fantastic John! I'm following in awe.

 

I really like those old airplanes with folding wings.

[John Rickett 102]

The left wing was progressed sufficiently to allow sorting out the hinges and making sure the dihedral was the same as the right wing.

 

 

I was quite pleased with the result so thought I’d drop the fuselage over the centre section to see what it all looked like. At this point I realised I’d made a catastrophic error, the geometry of the wing fold is completely wrong meaning that when the wings retract, they follow a descending arc and end up below the level of the tail wheel by a considerable margin!

 

 

The reason is that the dihedral was incorporated into the centre section ribs not the outer panels, I did this to maximise the available thickness of the wing which occurs in the centre section and reduces progressively toward the tips. I didn’t think at the time that having the hinge axis at the dihedral angle would have any effect on the wing fold, but of course it means that the retraction plane is angled……..in the wrong direction.

 

Having played with making up some more hinges to move the hinge axis in the opposite direction, which works to some extent, I’ve concluded that the gap between the centre section and the wing would be too great.

 

 

It would be major surgery to cut out the hinge supports, straighten up the centre section outer ribs and start again, as well as adding weight, so I’ll just have to live with the situation.

 

 

Here the wing is now higher than the tail wheel but there would be a large gap to fill between the centre section and wing which would also put the trailing edge out of alignment.

 

Its not the end of the project, the wings will still fold for transport if a tail support is made to keep the tail off the ground sufficiently, but with the wings stowed it looks a bit silly and defeats the original intent of a practical model with folding wings. 

 

This model may now be put on the back burner until enthusiasm is rekindled.               

[Ace]

I am gutted for you John as I have been following your progress with great interest.  Hopefully a solution will emerge once your disappointment has subsided.

[Richard Crapp]

I don't think that is a big problem . You just have to alter the vertical plane of the hinge.

Like re-fix it with the bottom of the hinge more to the rear. You might have to insert some more hard wood.

The real one had warnings about not stressing the hinge area , the tips to be supported during the fold process.
  In the  pictures you can see the tips nearly hit the flore when folded.

[RottenRow]

Don't give up John!

 

Could you make new bottom hinges, with the pivot point offset? Something like this drawing.

 

 

The modified hinges would mount in the same holes on the spar. The actual amout of offset required would probably be quite small.

 

The wingtips would then move on an upward arc as the wings are folded (viewed from the rear).

 

Brian.

[Basil]

16 hours ago, Ace said:

I am gutted for you John as I have been following your progress with great interest.  Hopefully a solution will emerge once your disappointment has subsided.

Ditto.

Bas

[alan p]

If the hinges are set vertical  in the ribs when folding the wing it will adopt the incidence angle of the wing, as the others have said pitch the hinge equivalent to the incidence or slightly greater to the vertical and it should fold parallel to fuz centre line. Excellent build so far shame to halt now👍

[John Rickett 102]

Thanks for the commiserations and good suggestions, repositioning the lower hinge pivot more to the rear would probably be the least amount of work. I think I could experiment with the left wing as little has been fixed which cannot be easily cut away. It would need some 2mm flat bar about 25mm wide, if anyone knows of a source?

 

 

 

If it works for the left side I'd be a bit more confident about cutting into the right.

 

 

The folding flap section may have to be relieved at the top and bottom to make space for a repositioned hinge but it’s hardly a stressed area, spruce was used only to allow the hinges to have a decent anchor, so would be simple to modify.

 

 

The top hinge would need remaking and angled back to allow the M3 bolt to line up on all the holes. The hinges are only 2mm mild steel so will withstand a small amount of twist which will be easier than making the wood supports with an angle which accommodates both the dihedral and the offset we are now talking about.

 

 

The first idea was to move the top hinge forward, but moving the lower one back is a better suggestion.

 

 

This is the view from the underside of the centre section, right hand side.

 

I really don't want to straighten the centre section ribs as I'm sure it would end up weaker. The undercarriage mounts are right at the edge and the holes were awkward to get right, plus the leading edge is now in the way.

   

After the last few days of deliberation, I’m now a little less circumspect and hope that the original plan of practical folding wings can be achieved. The model was always going to be sport scale, my building skills aren’t to competition standard, so these modifications won’t potentially lose any scale points.

 

Schoolboy trigonometry will have to be brushed up to calculate the amount of offset which will put the wing tip just under the tailplane. As there is the existing dihedral which was the original culprit, I don't think its a simple calculation, but a bit of experimentation without spoiling what is already there will probably yeild a result.

 

Interestingly, the picture below shows the Proctor wing fold attachments (this one awaiting restoration at East Kirkby) and there doesn’t appear to be an offset in the rear mounts, perhaps there doesn’t need to be if the end rib is perpendicular – my fundamental mistake I think.

 

 

The Proctor was the military successor of the Vega Gull and apparently retained the same wing fold.     

[Nick Cripps]

As a first approximation, measure the distance you need to raise the wingtip to match the desired height relative to the tailplane. Divide that measurement by the distance from the wingtip to the hingeline and then multiply the result by the vertical distance between the top and bottom hinges. This will give the rearward offset required for the bottom hinge (with the top hinge remaining in the same place, albeit twisted to match the new hinge axis).

 

I don't think the dihedral will make any difference to this calculation so the principle of "similar triangles" should work.

[RottenRow]

2 hours ago, John Rickett 102 said:

It would need some 2mm flat bar about 25mm wide, if anyone knows of a source?

 

You can buy this from B&Q. 25mm x 2mm x 1 metre length.

 

https://www.diy.com/departments/black-varnished-drawn-steel-flat-bar-l-1000mm-w-25mm-t-2mm/254141_BQ.prd

 

Wickes also sell some sizes, but only upto 20mm wide in 2mm.

 

Brian.

[Richard Crapp]

Any build news John.? I look forward to them. I am just getting a bit more done on mine.

[John Rickett 102]

Richard, pleased to hear you are making progress.

I played around with some offset hinges and did get the wing to fold just below the tailplane but the wing join wasn't pretty. As the model wouldn't be ready for this year, setbacks or not, I decided to concentrate on two other models in need of some repair and restoration which could be brought up to the painting stage by the time the weather improves. These are on track so hopefully I'll be back on the Vega Gull in the spring although I don't tend to get a lot done in the workshop during the warmer months.

I'm resigned to having the Gull's wings fold well below the intended position, which won't affect the looks, once assembled, or the flying but of course will look very silly sat in the van.

Us modellers have to be made of stern stuff!            

[Richard Crapp]

It's about the same with me. I had to put the gull aside to freshen up the 12 year old Wessex try-motor that may be called for flying duties.

It's done except for test flights so I can now tinker with the Gull but wont get it flown this year.

 

I was going to ask if you knew how many hinges the rudder had? but i decided on 3 and its done now.

 

Don't get to hung up by folding wings. I found out with the Swordfish they can be more trouble than their worth.

Mine fold but only after I remove the wing tube!

More of a party piece than useful.

[John Rickett 102]

While having to wait for decent painting weather for two other projects, I thought it therapeutic to progress the cabin interior.

 

With Beryl looking a bit more life-like with some colour in her cheeks and with a new completed control column to grasp and straps to keep her in position, it was time to prove that she and the tanks could all be fitted through the doorway.      

 

 

 

Major surgery was required on her feet (her ankles had to be removed) to clear the obstruction of the radio tray, even so as the butchery is low down below the instrument panel, I don't think it will be very visible. Beryl didn't say a word.

 

I doubt a four-point harness would have been fitted originally but to my mind its in keeping with a perilous record attempt and its all that holds her in the seat.   

[Richard Crapp]

Nice advantage of those huge tanks is that it will save you from detailing the cockpit.

I did not want to see here toes anyway!

[John Rickett 102]

Satisfied that the cabin interior parts would go through a doorway with sufficient margin, attention was paid to making the doors.

With multiple curves, the challenge was how to make them to hold the correct shape, yet be light and strong. I first considered making a mould and laying them up in fibreglass, removing all but the frame afterwards. I’m sure this could have worked but I wanted a way of building in a rebate for the glazing. There may be other suitable methods but I settled on making them out of laminates of ply having first proven that the ply would bend sufficiently and then hold its shape and that the corners could be made strong. The frames couldn’t be more than ¼” wide otherwise the result would look clumsy.

 

A couple of test pieces were made up as in the pictures

 

0.9mm ply once wetted and allowed to soak for 10 minutes then laid up in 3 strips over a suitable former, will hold its shape.

 

 

By overlapping alternate corners, the strength is as high as it needs to be. No attempt has been made to force the joint to destruction, but in pulling at it as if it were a wishbone, satisfied me that this type of joint is more than adequate.    

 

 

 

The doorway former was made form scrap bits, covered in parcel tape or Sellotape and clamped into position. Each side has a curve to some degree. 

 

    

 

It was then a case of adding the ply strips and slowly building up the layers.

 

 

There are 6 pieces to each layer with 6 layers required to get to the desired thickness. With each strip being wetted the drying time takes longer so is quite a slow process...but we're getting there.

 

  

[Richard Crapp]

Strangely I was working on the Gull 4 dores yesterday. They are a different style to your Vega Gull. Part of the Gull evolution.

The top at the moment comes off and can be hinged to the rite. To make the dore on the left open will require some sawing!

https://www.rcscalebuilder.com/forum/forum_posts.asp?TID=35651&PN=1&TPN=15

 

There are three nice photos here  including the cabin

file:///C:/Users/Richard%20Crapp/Desktop/PERCIVAL%20GULL%20IV%20-%20Classic%20Aircraft%20Sales%20Ltd.htm

[John Rickett 102]

With the shortening and cooling days, residence in the workshop is becoming more appealing and with it a view to continuing with the Vega Gull.

Spring and summer were not entirely neglected on the modelling front as an SE5 repair/restoration project was completed and the model subsequently sold. Also, a 20 year old Chrislea Super Ace which was looking rather decrepit has been recovered and painted, hopefully it will fly more frequently next year.

 

Some thought over the last few months has been spent on the shelved Vega Gull and what to do with the wing retention. So far I’ve rejected the options for having a scale wing fold given my limited workshop facilities and will probably simply use the existing lugs (in their present position) to attach the wings. To prevent this project from being a disappointment and permanently shelved, I thought that if I progressed parts other than the wings I’d get myself into a psychological position where all the other difficult and time consuming bits had been done, therefore it would be daft to shelve the project with so little else to do!   

 

With the building board cleared the Vega Gull was resurrected, with the first task being to get the other door made and both doors hinged. The method adopted for the first door worked, so why change things for the second. Suitable scrap wood was fashioned into a template for the inside of the doorway and then six layers of 0.9mm (1/64”) ply were laminated to form the shape.

 

 

The hinging was from cut-down strip hinges that had been squirrelled away years ago waiting for a suitable use. The hinges are 2.4mm thick so a recess was needed in both the door and jamb or an ugly gap would have resulted.

The next problem then was how to cut the rebate leaving a nice straight and flat surface for the strip hinge. The layers of ply, once laminated, form quite a hard material which I doubt could be reduced evenly without using some mechanical assistance. The solution was to make a straight edge (two actually) from flat bar, clamp them in turn to the door and jamb, sanding down with a rotary file. The method worked quite well.

 

 

 

 

The next task was to latch the doors. With them being such an unusual shape, they really needed latching at both top and bottom corners. Small neodym magnets offered an unobtrusive, lightweight way of holding the doors in just the right position. Not wanting to drill into the corners and weaken them, small fillets were added, which wouldn’t be seen when the doors were closed.

 

 

A feature of the Vega Gull, though not exclusive to it, is balance springs for the doors. At rest the tail sits down which makes the doors hard to push and keep open, so designed in is a cable attached to the outside of each door which attaches to a spring under the cowl. It was a fairly simple job to replicate and added minimum weight.

 

 

 

If anyone is wondering....the incomplete instrument panel is only temporarily installed for effect, its also held in place by neodym magnets so is easy to extract.

 

The doors have been progressed enough for now, the glazing and the chromed glazing bars will be fitted once the model is covered. The next job is getting some detail onto the cowl and then attention can return to the wings.  

Edited October 18 by John Rickett 102

[Ron Gray]

Glad you've got back on this build John and look forward to seeing it in the flesh at next year's Best of British at Buckminster!

[Richard Crapp]

37 minutes ago, John Rickett 102 said:

With the shortening and cooling days, residence in the workshop is becoming more appealing and with it a view to continuing with the Vega Gull.

Spring and summer were not entirely neglected on the modelling front as an SE5 repair/restoration project was completed and the model subsequently sold. Also, a 20 year old Chrislea Super Ace which was looking rather decrepit has been recovered and painted, hopefully it will fly more frequently next year.

 

Some thought over the last few months has been spent on the shelved Vega Gull and what to do with the wing retention. So far I’ve rejected the options for having a scale wing fold given my limited workshop facilities and will probably simply use the existing lugs (in their present position) to attach the wings. To prevent this project from being a disappointment and permanently shelved, I thought that if I progressed parts other than the wings I’d get myself into a psychological position where all the other difficult and time consuming bits had been done, therefore it would be daft to shelve the project with so little else to do!   

 

With the building board cleared the Vega Gull was resurrected, with the first task being to get the other door made and both doors hinged. The method adopted for the first door worked, so why change things for the second. Suitable scrap wood was fashioned into a template for the inside of the doorway and then six layers of 0.9mm (1/64”) ply were laminated to form the shape.

 

 

The hinging was from cut-down strip hinges that had been squirrelled away years ago waiting for a suitable use. The hinges are 2.4mm thick so a recess was needed in both the door and jamb or an ugly gap would have resulted.

The next problem then was how to cut the rebate leaving a nice straight and flat surface for the strip hinge. The layers of ply, once laminated, form quite a hard material which I doubt could be reduced evenly without using some mechanical assistance. The solution was to make a straight edge (two actually) from flat bar, clamp them in turn to the door and jamb, sanding down with a rotary file. The method worked quite well.

 

 

 

 

The next task was to latch the doors. With them being such an unusual shape, they really needed latching at both top and bottom corners. Small neodym magnets offered an unobtrusive, lightweight way of holding the doors in just the right position. Not wanting to drill into the corners and weaken them, small fillets were added, which wouldn’t be seen when the doors were closed.

 

 

A feature of the Vega Gull, though not exclusive to it, is balance springs for the doors. At rest the tail sits down which makes the doors hard to push and keep open, so designed in is a cable attached to the outside of each door which attaches to a spring under the cowl. It was a fairly simple job to replicate and added minimum weight.

 

 

 

If anyone is wondering....the incomplete instrument panel is only temporarily installed for effect, its also held in place by neodym magnets so is easy to extract.

 

The doors have been progressed enough for now, the glazing and the chromed glazing bars will be fitted once the model is covered. The next job is getting some detail onto the cowl and then attention can return to the wings.  

Glad you are back on it John. I also had trouble with the folding wing hinge in that the small brass hinges, 5 pr side , where i was going to insert the pin to allow the fold.

Total wast of time!    I have gone back to Merlin Locks to retain the wings on the tube. Apart from that I am ready for taxi tests. It weighs 28lb.

  if you want to have a look.

https://www.rcscalebuilder.com/forum/forum_posts.asp?TID=35651&PN=1&TPN=30

https://www.rcscalebuilder.com/forum/forum_posts.asp?TID=35651&PN=1&TPN=30       

[John Rickett 102]

Thanks chaps for the encouragement. Having paid a brief but enjoyable visit to the Best of British event this year and seen the way its being run, I would like to go to the next one, probably with the caravan in tow, so that prospect is a further incentive to make progress.

 

Richard, I like the foot-hold flanges you’ve made and will attempt the same trick of using a cutting machine. I’ve only cut paint masks before and not considered cutting plasticard, you’ve obviously had success with these thicker materials. Did you use the same (standard) cutter blade?

 

The intake flange on the cowl was made using litho, which worked ok though is probably a bit too wide, using a cutting machine means that small items not easily gripped by hand could be produced more accurately.

 

 

Looking at pictures on your RCSB site which include the foot-holds and then measuring a shoe, I make the presumption that they would have been about 12” x 6” therefore 3” x 1½” at ¼ scale, did you come to a similar conclusion?           

[Richard Crapp]

Using my Silhouette machine on some fairly thin plasticard I increases the blade pressure to about 6 .  There is also a setting for thin card that i used.

Same blade.

The shapes get to a pop out stage then you just help them out of the card by flexing. I did the D window (that is on a Gull 4) in the same way.

 

For the foot holds on the wing, (only one side on a Gull 4,) I measured them off against the known model chord.

Berell dose not look like she has size 12 feet in the picture you posted on page one !, but even so they do not fit in the foot hold.

So mine are 2.5" long and 1.4" wide including the border.  Model is 3.7 scale.

 

If you have a Silhouette machine I am tempted to offer to send the files but i have never sent cutting files and it might stretch my non computer brain.

Easy to re-size them though.

 

[John Rickett 102]

Percival’s designers added a bit of flair when it came to The Vega Gull’s carb air intake, it’s a long, streamlined affair extending to one third the length of the cowl. It was fairly easy to make so couldn’t be omitted on the model.

 

 

A plug was made from scrap B&Q plywood, sanded to an acceptable shape, and covered in one layer of 100 gm fibreglass cloth. Following 6 coats of release wax, the intake was formed with 3 layers of 100 gm cloth and left to harden overnight.

 

 

The next morning the moulding was given a further coat of resin to fill the weave and then left for two days to cure sufficiently for sanding. The intake would be an awkward thing to hold while rubbing down but the plug makes the prefect grip so rubbing down to a finish was achieved prior to releasing.   

 

 

 

 

The plug had been made longer than needed and with deeper sides than the finished intake so that it could be cut down to the correct dimensions (which were an estimate anyway but shown against a photo of a remaining Vega Gull for comparison) and to form lugs which would slot into the cowl and provide a substantial fixing.

A tungsten carbide disc is ideal for cutting fibreglass, anything else is quickly blunted.

 

 

There is a double row of hinges on either side of the cowl. Presumably this is so that the hinged portions could be folded right back without straining the hinges.

The hinges were replicated by marking out and cutting slots (1/2” pitch) on both long edges of a strip of litho.

 

 

This was the second attempt, I had made a pair with 3/8" pitch as I guessed that the real thing would have been 1 1/2" pitch, however on a recent visit to Old Warden I got the chance to measure their Hawk Speed Six cowl hinges and found they were 2" pitch....the others are now in the bin. 

 

The strip was then held in position by a straightedge and each tab lifted through 90⁰ before pressing and rolling back down again with a length of 1mm piano wire underneath.

 

 

Before attaching the hinges the panel lines were added using fine tape followed by a few coats of epoxy primer to build the depth. The cowl panel line also set the limit for the hinges

 

 

 

Once dry,the primer was cut back with wet & dry until the colour of the tape was visible and then peeled off. 

 

The simulated hinges were glued into place with contact adhesive and then given a couple of coats of primer to seal against any subsequent fuel or exhaust ingress. The coats of primer tended to fill in the previously cut slots so these were carefully scratched across with a knife to try and make the gaps more prominent.

 

 

Before gluing on the carb air intake the area was sprayed with the finish colour as it would have been impossible to reach later and would have left an unsightly white bit.

As there was some paint left in the gun, it seemed a shame for it to go to waste so couldn’t resist the opportunity of seeing what the finish will look like……..turquoise is a bit garish but who am I to comment on the taste of a Percival customer of 1936. On my screen this looks like light blue, but its even more garish in daylight!     

 

 

[Richard Crapp]

I found this picture of the foot holds

[John Rickett 102]

Thanks for the photos Richard, its heartening to know that you’re taking an interest in my amateurish efforts. Construction has reached the stage where the wing centre section and fuselage need to be mated, but before that can be done the radius of the fairing needs working out as the edge of the fairing will determine how far the footholds are from the fuselage. I’ve given myself some problems here as the footholds need to be installed in the 1/8” wing sheeting before the wing and fuselage can be glued together. The fuselage is going to be stuck directly onto the wing sheeting so the centre section sheeting needs to all be in place first.

 

 

 

After studying quite a few photos which include the ones you’ve sent and the ones of Beryl Markham and Jean Batten’s feet (!) and measuring my wife’s more sensible shoes, I’ve concluded that the footholds would have been about 8.5”x 5”. As best I can judge, it looks as if the radius of the fairing ellipse was 5”.

 

 

These dimensions could well be wrong of course but provided they are not grossly out of proportion, it will be good enough for what is essentially a sport model. When designing the Vega Gull I gave scant attention to the wing fairings and now find I didn’t build in the support for the fairings on the fuselage sides, extra balsa has now been added to provide a fixing and to allow for blending in. The fairings look as if they were attached after covering and possibly removeable so I’ll try and incorporate a step at the edges with masked primer.   

 

The next consideration was how to make the footholds, and mount them, with the least weight gain. The options were to laminate a few layers of 1/64” ply around a former and them glue on a base, or wrap litho around a base. I decided in the end to try making them out of fibreglass, the benefits being that if moulded there would be nothing to come apart later, minimal weight and all four would be identical.

 

A plug was shaped (intentionally made too long and too high so that the subsequent casts could be trimmed later on) and covered in two layers of 80gm cloth, then once dry, a further coat of resin was applied to fill the weave and finally rubbed down to a smooth finish after leaving to harden for a couple of days.

 

 

Two layers of 19gm and one of 50gm cloth produced a result which weighs 4 gm. I’ll call this one a test piece as the inside corner is a bit rough (needs some gelcoat adding before glassing I think). The result is encouraging though so will persevere with moulding the footholds in fibreglass.