Pop Rivet Removal

You have to remove a number of temporary factory rivets to commence assembly of various parts of this aircraft. The pop rivets used do not have a full length mandrel and are therefore easily removed using a drill on the center of the rivet to remove the head.

This builder only has access to battery tools which operate at much lower rpm compared to air operated toosl shown in the video below. Their advantage is they are relatively quite and are ready to use on demand. An unstated advantage is that most people that surround us are unlikely to be in love with your compressor running to provide air on demand.

Note:  Set the clutch at it lowest setting to ensure that if there is the slightest increase in load it should release the clutch. Ensure the battery has a good charge to provide maximum revs.

Select a sharp drill that is slightly smaller than the head of the rivet to be removed. Drill to about the point shown and at this point pulse the drill as it is close to breaking the head free. Keep drilling using small pluses until the head breaks free.

Note: For the 3.2 mm rivets a 4.5 mm drill works well

Drill Rivet

Stop & Pulse Drill from here

Head sheared off

Remove the rivet using a small punch to drive out the mandrel or if you have access to the rear of the rivet remove with a pair of side cutters with a rolling action.

Generally this works but this builder found the rivets that secured the skin at the top longeron were another case [location shown above]. After a number of blows of ever increasing force, it was clear the lack of structural rigidity was not allowing the blows to do their work and there was NO rear access.

At this point it was decided to resort to the drill, not the favored option as you can loose control easily.  Punch out the mandrel with a 1.5 mm punch then drilled out the stem using a sharp 2.5 mm drill until it breaks free, generally before reaching its end - little force is required just great care. 

  Removing Pop Rivets

Dimpling Skins

Flush riveting the first 30% of a flight surface can effectively reduce the majority of parasitic drag created by riveting with the remainder of the wing providing little drag reduction for the additional work.

Begin located in Australia C press riveting frames were unavailable and due to cost and size airfreight was not a option. It was decided to examine the use of a low cost option of using a dimple die and pop riveter.

Dimpler - click link 

Aircraft Spruce lists a 120 deg dimpling tool to suit the Cherry G-28 pop riveter. This unit is designed to screw into a Cherry pop riveter tool but as luck would have it did not suit my unit. With no alternative available it was decided to modify the die and the threaded portion was cut off. 

Note: There are other dies available that are universal but this one created the result illustrated

A trial on one rib indicated that the tool created a usable countersink in the rib and the decision was made to proceed to dimple the leading edge of the elevator stab to the face of the spar. If you were planing the next grand champion then it would pay to use better equipment but this is beyond my ambition and skill level. 

Modified Dimpler

The final result is dependent on technique and this builder will describe his method as clearly as is possible below. 

The nails provided have about a 0.25 mm clearance in the pre-drilled hole so the best method is to install the female die at the rear then place the male at the front of the component. 

For ribs use a thumb and forefinger to support the female die and too center the male on the hole. Mount the puller and while holding it about 1/3 along the handle close the two dies to hold the dies in potions and apply light squeeze, next place the other hand at the end of the handle  and apply firm pressure clamping the dies closed.

Update 11/5/16:  A new tool has been found to create a better dimple - Click 

For the skins use the same technique but fit the rivet gun, apply LIGHT pressure and wriggle the male die until it "Clicks" into center off the hole then repeat the technique above.

The nail will require light dressing to remove the ribs created by the tool from time to time - this becomes less with use and this builder used two nails for the elevator stab. When correctly centered there is a very short stroke required to form the dimple. The factory supplied rivets fitted neatly into the assembled countersinks.

Footnote: The blue painters tape covers the holes that fix the skin to the spar. They are in place to prevent the builder accidentally applying a dimple to any of these holes as time passes working and the builder enters a derrrrrrr..!!!! zone. Knowing this a series of NO RIVET was also added with a felt tip pen. A story for a future blog will illustrate how errors are created by human performance during assembly.

Completed Elevator Stab

Stab fitted into the Assembly Jig

Comment - 21/6/18
I purchased a CherryMax riveter to fit the die as it was easier and helped when the nail broke as the two components just took off - Tried another similar product from another supplier and this one produces the best dimple.

Nut Plates

As part of the assembly the spars of the aircraft tail require nut plates allowing installation and removal of various components without access to a nut. This task is was accomplished using simple jigs and micro stop countersink.

Drilling Nut-plates
Using a piece of dressed timber, drill a 5 mm hole through then using a #8 screw  of sufficient length to engage the plate. Insert the screw through the hole and then fit a nut plates supplied with the kit and drill a 1.5 mm hold through one of the lug mounting holes. Insert a a discarded pop rivet shaft as a locating pin as it adsorbs the torque of drilling and its a true finger saver.  

Drill the hole on the opposite side to the pin 3.2 mm [1/8''] through, remove and refit the nut-plate and drill the other side and de-burr. 

Now all that you do now is the rest - Joy..!

Drilling Spars Nut Plates
While some of the spars in this kit had the mounting holes for the rivets to fix the plates drill they were not on the elevator stab spar but all require countersinking. Locate a #10 bolt or screw and fit into a unmodified nut-pate to a depth to secure the two items. Trim off the head of the bolt with a hacksaw and you have a low cost drilling jig. 

Mark a straight line across the center's of the factory holes using a felt pen and insert the exposed shank into the factory drilled hole and align the two mounting holes with the line. Mark and drill the first mounting hole, secure the nut-plate using a cleco from the rear then drill the next hole. 
Repeat for all the mounting holes as specified in the plans.

Countersinking Nut Pales
If purchasing a new micro stop investigate a slim line for this job especially for those in the rudder fin spar and remember to purchase 1/8'' cutters to suit the selected tool. This builder used an full size economy micro stop that was in the toolbox. 

Note: Countersunk pop rivets have 120 deg NOT 100 deg angle as a solid rivet.

Slim Micro Stop & Cutter

Nut plates should be aligned along the length of the spar especially on the rudder fin. Drill test holes in a piece of scrap and adjust the stop to the correct depth then countersink all the mounting holes and install the plates with 1/8'' counter-sunk pop rivets supplied. When riveting, fix the nut-plate to the spar with a short 3/16'' screw, align hole and pop rivet with the countersunk rivets supplied with the kit.

Countersunk holes have a tendency to find their own centers and are notorious in their lack of accuracy about the hole center-line they are applied on.

This nut alignment was missed by this builder on the rudder stab and resulted in some untidy work to fix the issue. 

Footnote: Countersunk 3/32 pop rivets are available but hard to source and not available from the usual home builder suppliers.
Apex Fasteners have one with a 3.2 mm grip, a bit long but you might get away with it. The gain is not having to drill the lug as outlined and the countersink should fully terminate in the 1 mm spar material. 

Metal Cutting Update

In the previous article about metal cutting examined the use of a Olfa Cutter to trim sheets. Franco at Flying Legend advised that the factory had supplied stainless steel strip drilling jigs. A quick search of the parts supplied identified a stainless steel strip 20 mm wide punched at a 30 mm pitch. This had been packed away with the thought that this looked very important and must therefore go somewhere important - not so. 

Its application is the same as the cutting guide outlined in the original article but its can also be used as a drilling jig for the fixing of components. Begin steel it provides a convenient edge guide when dressing the cutting burr with the file.

The other items shown with the punched strips is the flat strip to manufacture the attachments of the fiberglass tips to the aircraft. The folded 30 x 30 angle is just that, folded angle to allow the manufacture of various brackets as required by each individual aircraft.

Metal Cutting

Drilling jig

Disclaimer

Disclaimer

Legal Notice: The builder states that construction methods and procedures employed during the assembly of the blogger's Tucano R aeroplane kit, produced by Flying Legend, are not in any way to be connected with Flying Legend official documented instructions. 

By no means should readers of this Blog interpret the content therein as approved assembly procedures or official instructions by Flying Legend.

Construction techniques, comments, suggestions, experiences, design modifications, error correction, product usage and photo displays contained within this Blog are in no way to be construed as approved methods or instructions for the Tucano R airplane or any other aircraft. 

Before utilizing anything seen or read within this Blog, consult with a trained, licensed and approved aeronautical professional or technical adviser from your approved authority. 

Above all I am no writer and will over time return to a blog in an attempt to tidy up my poor writing skills and improve the readability - I apologize in advance

But above all have fun

Frank Walter Cale Pilot Officer

Spit-tano

Registration
The paint scheme chosen is the 2010 RAF- 50th Anniversary Battle of Britain Tucano demonstration team aircraft and it was decided to create an Australian link. [See: Styling] 

UO was the prefix for 266 squadron in 1940 and H appears on the grave marker Most aircraft carried UO with no unique ID due to the loss rate at the time.

Spitfire MK1 flown by Walter Cale

His aircraft was a Spitfire Mk 1A serial number N3168, construction number 410. 

Why Frank Cale?  - Like a lot of the unknown pilots, he lost his life paying the price for our collective attraction for evil men while receiving none of the public glory associated with the victorious but known in history as "One of the Few".


WAR RECORDS

On the 15th of August, the 266 Squadron scrambled against a Luftwaffe raid and were heavily engaged over Kent. In a stiff fight, the 266 lost Pilot Officer Frank W. Cale was shot down in his Spitfire Mk 1 (N3168) near Maidstone, Kent at 18:50 hrs. He was seen to bale out and his parachute opened.

However, all that could be located on the ground was his parachute with burnt straps. Cale's body was recovered from the River Medway on the 16th of August 1940.

He was aged 25 when he joined the Few.

This story is better told by the Kisten Alexander Blog 

Combat Report lodged by F. Cole 2nd June 1940