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by David Jones
December 3rd, 2010, 5:49 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

The top hatch was made up by utilising wing seat W3, and the previously cut off formers F7 and F8. The ends were made up to match formers F6 and F9. The structure was built up in situ to ensure it lined up with the fuselage. In order to secure it in position, I decided to glue 1/4” lite ply tabs to ...
by David Jones
November 12th, 2010, 12:18 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

Soft block was again used for the end of the fuselage. Provision was made for the rear guns by pre drilling holes in the tail block and fitting 2 x 4mm captive nuts, the idea being that the guns can be removable to reduce the likelihood of damage in transit. I’ve made up a pair of guns by epoxying s...
by David Jones
November 12th, 2010, 12:15 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

It was time to turn my attention to the tail end and the fairing-in of the removable tail plane. The top section aft of the tail plane was made up from soft balsa block, carved and sanded to shape before being permanently fitted in place. Further sanding and shaping was then required to blend in wit...
by David Jones
November 12th, 2010, 12:12 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

The servo wires for the four tail end servos were put in place and labelled up. A ply plate for the nose leg (steering) servo was made up and fitted in situ before the top stringers were added. Formers F6 and F9, which will be the front and aft ends of the hatch cut out, were faced off to add some r...
by David Jones
November 12th, 2010, 12:09 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

Now that we have decided the centre section will be removable, the lower hatch area will have to be strengthened. The lower sheeting beneath the wing / hatch area was stripped back a full bay fore and aft, two new lower formers, F7 and F8 were made up and fitted. Stringers were added off set, so tha...
by David Jones
October 22nd, 2010, 8:42 am
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

The outer panels were then attached to line up the flap cut outs and the flaps finished off to fit. All the control surfaces were then dry fitted, the wing stood on its tip in all its completed glory and pictures taken, even the wife was impressed. While it was in this state, I couldn’t resist wedgi...
by David Jones
October 22nd, 2010, 8:41 am
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

The top sheeting has now been added and the nacelles finished off, the air intakes will be added after the wing has been glass clothed. The 5/16” balsa leading edge was then added and sanded to shape.
by David Jones
October 18th, 2010, 5:20 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

All that remained now was to fit the ply tongue at the leading edge of the tail plane and to beef up the ribs in the centre section with some hardwood spars to spread the load of the wing mounting blocks. The model was then taken to be inspected by Dave Johnson who passed it with flying colours and ...
by David Jones
October 18th, 2010, 5:13 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

All that was required now was for a fine day at the weekend, setting the wing up for accurate fixing to the fuselage needed plenty of space, so indoors was out of the question. Alan came across and we set the model up in the back garden. I had already drilled pilot holes in the hard wood blocks, so ...
by David Jones
October 18th, 2010, 5:10 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

The same principle was used to mount the removable tail plane, though there would be just two 4mm wing bolts at the rear into a 1/4” ply plate fixed across the tail plane seat, and a 1/4” plywood tongue at the front, which would locate into a strengthened F12, similar to the main wing on a sport mod...
by David Jones
October 18th, 2010, 5:09 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

The decision regarding “do we have a fixed wing or a removable wing” has always been a topic of conversation and lengthy discussion re the pro’s and con’s of the build. As far as the build is concerned it doesn’t matter, it’s as easy to make the wing removable as it is to have it permanently fixed. ...
by David Jones
September 9th, 2010, 8:00 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

There is still some work to do on the centre section before it is fitted to the fuse. When that is done I’m not just going to rely on glue, I’m going to fit some blocks and plates and bolt it in position as well. However, before I do commit myself to permanently fitting the centre section, I would w...
by David Jones
September 9th, 2010, 8:00 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

The centre section is going to be permanently fitted to the fuse and, in order to install it, the upper half of formers 7 and 8 have to be removed, along with the stringers. Once this was done the centre section was offered up. There was a considerable gap between the bottom sheeting and the wing se...
by David Jones
September 9th, 2010, 7:57 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

The engine nacelles on the centre section have now had a layer of glass cloth on them, and the glass cloth panels to cover the retract cut outs have been made up and only require cutting to size. The underside of the nacelles were cut away to allow fitment of the retract units onto the bearers. Beca...
by David Jones
September 9th, 2010, 7:54 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

One job I forgot to do was the air scoops on the outer wing panels. For some reason I thought they were on the centre section, so a quick phone call to Alan and I got the panels back before he started to glass cloth them. I made up the front face from 1/8” lite ply, cut some aluminium gauze to shape...
by David Jones
September 9th, 2010, 7:53 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

The attachment of the second fin was accomplished in the same manner, but I had to use a short piece of board clamped to the bench to cater for the overhang of the first fin. Square datum lines were drawn on the piece of board as before and the second fin was attached. The rearward slant was measure...
by David Jones
September 9th, 2010, 7:51 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

It was now time to attach the fins to the tail plane. In order to ensure they were square with the tail plane, both back to front and top to bottom, and that they would be parallel with one another, I drew reference lines at the end of my building board to act as datum points. I weighted the tail pl...
by David Jones
September 9th, 2010, 7:49 pm
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

I left off where I had completed the elevators. All that was required now before the fins could be fitted to the tail plane was to accommodate the rudder servos. Hitec metal geared mini servos are to be used and they will sit upright in the fins, with the servo head sticking out of the inboard side ...
by David Jones
August 22nd, 2010, 9:44 am
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

The elevators were then made up from 1/8” balsa ribs and false leading edge, 1/2” x 1/4” trailing edge and 5/16” ends. The main leading edge is 5/8” thick, with a groove cut down the middle to accept the piano wire hinge. Again this groove was cut oversize to accept the brash tube bushes which run t...
by David Jones
August 22nd, 2010, 9:42 am
Forum: Your New Projects
Topic: Zirolli B25 Mitchell build
Replies: 118
Views: 51360

Re: Zirolli B25 Mitchell build

This idea was scrapped and the servos were mounted on their sides on a 1/8” ply plate. The false ribs were removed and hardwood bearers were epoxyed to ribs SR4 and SR5, the ply plate acting as both servo mount and hatch cover. The servo wires were then added and the bottom surface of the tail plane...

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