Komet

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flyvulcan

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I shall start with a photoshopped picture of my project to show what the final product will resemble. The tailfeathers are not accurately sized on this photo as it was a really quick attempt at photoshopping and it is not my strong point, but it is enough to give you an idea of what I am hoping to achieve. Also, the wheels will be faired on the finished aircraft. It is a 2 seat twin-jet, using a kit that was produced in the early 1990s, modified to incorporate the changes needed to make the configuration viable. The original kit was a single seater which came with either a retractable nosegear or a tailwheel. Mine was started as a taildragger and due to the removal of the regular engine from the nose and the subsequent requirement to put weight in the nose to replace the engine, i.e. the pilot, there is currently no room for the retractable nosegear so I will leave it as a taildragger for now. If it proves to be a handful on the ground, then I will look at changing it over to nosegear. I was originally planning to use either the Phill Heward H200N (now licensed to Obilaser) or the JetBeetle H150 Locust. However, I am now working with another engine manufacturer who will be providing me with 2 x 180lbs thrust powerplants for use on the Komet. I purchased the kit around 12 months ago in the USA but it only arrived in Australia around 6 months ago. Progress has been steady since then with the wings being the first item to be tackled. I am hoping to have them completed before christmas. I hope you find my progress interesting.

Flyvulcan

PS For interest, I decided to add another shot of my project taken in August 2011 to compare the original rough depiction with how it is 2 years later. So here's the shot from 2011.

8.jpg

and another depiction from 2012

Komet copy.jpg
 

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flyvulcan

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There are 4 of us working on the project. We started with installing fuel filler points in the leading edge D-cell fuel tank.

I should advise readers now that there was never a set of plans, nor construction manual for the kit that I bought, so we are working in real "experimental" land with this project.

That said, we installed the fuel filler points at the high point in the tanks. Here we ran into some strange idiosynchrasies in the construction of the kit. My tank had been pressure tested and passed with flying colors, but when we inspected the the wing closely (after installing the fuel filler points) we found some very small, but obvious holes between the front of the spar and the rear of the spar at the end rib. How could it have passed the pressure test... Also, when looking inside the D-cell through the filler point, the end rib was foam only on the inside... not good for being exposed to fuel. Also, the breather tube extended from the wingtip along the spar somewhere down towards the root... After much headscratching, we realised that the fuel tank did not extend the entire length of the wing and actually stopped 2 ribs in from the tip. We have resolved this and our solution will be seen in a few posts.

We are earthing/bonding the fuel system so you will see a strap from the filler point to the aft face of the spar. This is connected to a wire which runs down to the fuselage inside a conduit, which will also house any electrical wires for wingtip lights etc.

Here's the filler cap going in.
 

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flyvulcan

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After the installation of the fuel filler points, it was on to the internals of the wing.

This involved preparing the ribs which were installed aft of the spar to have a cap strip installed.

The ribs consisted of some which were solid glass and some which were sandwich (original kit ribs plus "new ribs"). The solid glass ribs had integral cap strips but the sandwich ribs needed cap strips to be fabricated. This involved firstly trimming the core back. Then the top skin, where the cap strips would meet the skin were prepared, had a layer of release tape added, then 2 layers of bidirectional cloth (bid) was placed on the release tape. The ribs were filled with flox and the top skin, complete with cap strips was put in place, thereby molding the floxed ribs to shape and loosely attaching the cap strips.

2 days later, the top skin was removed, peeling it off the cap strips by using the release tape. The release tape was then removed from the cap strips, leaving the cap strips in place on the ribs and nicely molded to the top skin. Bids were then applied to secure the cap strips to the ribs.

The following 2 photos are of one of the sandwich ribs having some of its core material being removed with a Dremel tool and of the top skin being held in place to mold the ribs capstrips to the correct profile.
 

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flyvulcan

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Work on the wing has been progressing well lately. My co-builder found problems inside the leading edge D-cell of his wing that were built in by the factory (it came already sealed). We had to do a great deal of rectification work on his wing, so we decided for peace of mind to give my wing the same treatment.
Two weeks ago, my leading edge was "cut off" to gain access to the interior of the leading edge D-cell.
The core material was trimmed out of the skins/ribs to a depth of about 3/8 inch. This is where flox will be inserted for rejoining the leading edge.
Joining strips about 2" wide were made out of 4 bids and these were bonded to the inside wing skin to give the leading edge something to bond to when being rejoined.
The fuel tank originally ended 1 rib in from the wing tip, but this has now been opened to extend the fuel tank to the tip. With my jet engines, I will need what fuel I can get!
All ribs have now been bid to the spar; after radiusing the join between the top/bottom skin and the spar, a bid has been applied from the top skin and over the forward face of the spar to the bottom skin to provide a better seal between the skins and the spar; the end rib was sealed in a similar fashion and strengthened (as it is now the end of the fuel tank); and the entire fuel tank was prepared and then resealed with appropriate sealer. I am now confident that I will have a stronger wing with more structural integrity and it wont leak fuel.
Next week, the fuel probe, earthing/bonding wire and breather tubes will be installed and the leading edge will be re-attached.
 

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flyvulcan

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OK, there was a bit of a hiatus while the builders attended Oshkosh and had a long break visiting the US.
Since their return, the internals of the leading edge have been completed including the fuel probe, earthing/bonding wire, breather tubes etc and the logistically demanding task of reattaching the leading edge has been completed. Thanks to all hands who helped out with this task. The join has now been tidied up since the attached photos were taken.
Also, the wing upper surface inspection panels have been cut/fabricated, with 2 in each wing (above the flight control bellcranks). These should be finished at the next workshop.
It will then be on to finishing off the flaps, along with their associated hinges/brackets etc. which wont be too big a task.
 

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flyvulcan

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With the wings nearly done (hopefully finished within the next month), work has started on the fuselage. The empennage has come from another project and provides a larger vertical stab than on the original aircraft which will be required to address the one engine inoperative asymmetric situation.

This metal empennage replaces the original glass one as it is anticipated that there will be occasions when the hot exhaust gases may "warm" the tailfeathers.

The attached photo shows a trial fit of the empennage to determine the mounting requirements. Over the next few days, all empennage mounting/attach points will be fabricated and installed. The intention is to have a removable upper fuselage fairing for the empennage to facilitate easy removal/adjustment. There will need to be a measure of fairing of the rear lower fuselage to keep things looking neat at the tail end.

Progress photos will be provided over the course of the next weeks as the empennage is mounted. I also anticipate that the retractable nosegear mechanism/assembly will be installed in the next week, with the maingear already having been relocated aft to the correct tricycle gear location. I had decided to go firm on the nosegear option which will provide some benefits over the tailwheel option.
 

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flyvulcan

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The empennage has now been fitted. The aft bulkhead that is the mount for the vertical stab was moved forward about 6" from it's original position to facilitate the mounting of the new larger vertical stab. Two additional bulkheads were installed to mount the horizontal stab to. Horizontal stab incidence will be adjustable and will be accessible through a removable empennage fairing. Dont be concerned about the mounting hardware on the attached photos, it is just Sears nuts and bolts. The empennage has now been removed while more work is done on the forward fuselage. It will all be attached with correct AN hardware at the appropriate time.

The retractable nosegear has been mounted but we have some concerns about the angle of the nosegear when extended being insufficient. It is nicely flush when retracted. We are looking into this issue.

Tail fit small 3.jpg Tail fit small 2.jpg Tail fit small 1.jpg Nosegear small.jpg
 
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flyvulcan

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Here are a couple of extra photos of the work done this week. The shots include one of the new aft bulkhead where the vertical stab spar is mounted, one of the (rough and still to be finished) removable empennage fairing, and also the nosegear retract mechanism fitted to the wheel well.


Vert stab bhead small.jpg Fairing small.jpg Retract mechanism small.jpg
 

flyvulcan

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Wing

I have just completed three weeks of intensive building with my helpers. The wing work involved finalising the rejoin of the leading edge.

This was done by sanding back the gelcoat from within about 2" either side of the join and adding a 2.5" bid across the join, followed by a 2" bid on top of that. We are happy with the result and feel confident in the integrity of the wing as a whole, now that the repair is essentially complete.

We also re-installed the aileron control system (temporarily) to check for fit etc.

Here are a few shots of the work.

Bid application.jpg Leading edge rejoin.jpg Aileron bellcrank.jpg
 

flyvulcan

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Fuselage stretch

The bulk of the effort during this construction period was in the area of the fuselage stretch. A 15" stretch was decided on to facilitate maintaining the cg within the original envelope and to provide additional leg room for the front seat pilot, who was going to be quite cramped in the original fuselage.

The fuselage skin was cut at around the 25% chord position where both the side frames and the lower fuselage were parallel. This allowed us to add a simple straight sided plug into the fuselage (did I just use the term "simple"?...). The centre channel was cut around 18" forward of the skin cut so that the skin join and the channel join was not in the same location.

The first thing we did after cutting the fuselage was to repair the skin and channel where the maingear had been removed (as part of the reconfiguration from taildragger to nosegear). This was quite straightforward and involved the usual steps of jigging all components into position, preparing them for application of the bids used to join the components, then applying the bids.

Cut 2.jpg Jigging.jpg Maingear cutout repair complete.jpg
 

flyvulcan

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Fuselage stretch 2

A large sheet comprising 6 layers of bid was prepared to cut the various channel/fuel tank sheets from.

We then jigged the maingear into its' new location and prepared all mounting fixtures to be reinstalled. With the maingear jigged in place, all pre-prepared panels that were to be installed on the channel were jigged into place. The next day, a simple former made from a sheet of aluminium was wrapped around the fuselage in the area of the join. This was covered in peel ply and four bids were layed up against the former.


 

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flyvulcan

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Fuselage stretch 3

Here are some of the channel parts being located. The channel in this area is also the fuselage fuel tank.




The next day, all parts of the channel were installed and bonded in place,with the exception of the top sheet which will give us access to the fuel tank which is incorporated in the channel.

 

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flyvulcan

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Fuselage stretch 4

The gear was then secured in its' final location with the mounts being bonded to the skins/channel and all mounting hardware was installed.

Here is a photo of the gear leg positioned in the lower fuselage:


Gear leg.jpg

Here is a shot of the mounts bonded into place:

Gear mountings.jpg
 

flyvulcan

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Fuselage stretch 5

The next step was to bid the outside skin of the join. I forgot to mention that there is a foam core longeron about 6" in width which runs the length of the fusleage. We had to incorporate some foam into the skin of the join to continue this longeron. We applied 2 bids as the outside skin, making a 6 bid join in total.

Bidding outside of join.jpg Bids complete.jpg
 

flyvulcan

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Fuselage stretch 6

We chose to add additional longerons over and above the ones included on the original design as a result of the 15" stretch.

A 1/4" x 1.5" hoop pine strip was run from the nose bulkhead to the tail, with a doubler for the front seat to engine mount location and a tripler across the centre of the join. This longeron was bonded in under the lip of the lower/upper fuselage join and was covered with 2 bids.

Here is a pic of the longeron bonded in place but before the bids were applied:

Longeron.jpg

I've not included the nitty gritty of all the steps in this process. There was a lot of fitting, trimming, sanding, mixing, drilling, painting etc. that meant around 200 hours of labour were expended over the last 3 weeks, but it has all been worth it with great progress being made.
 

flyvulcan

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Taking the work home

After we did all the work in Henry's workshop, I took my project home to store it until the next session. I took a few pics of it in the driveway. Here are some of them (some might note the slight flaw that will be sorted during the finish process).

P1020477.jpg P1020480.jpg
 
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