Ready for prime time!

It has bee quite a while since my last post, as work has kept me (far) away from the Pelican project, but now I am back in Lima for a month or so, so we are moving full speed ahead on the project.

While away, had to find something else to do :)

While I was away, Gamal and Juan pretty much finished the fabric covering of the whole plane. The covering took a while (because of other planes getting on the way) but it was pretty much uneventful, except for an issue with the aileron tips.

The issue was with the tip of the aileron. Specifically, the when the aileron was covered with fabric, the tip area bent under the stress of the tightening fabric.  It could be that to the fabric was heated to tight... but my guess is that there should have been one more rib on the aileron between the last one it had and the end of the aileron.

The reason I think this, is because the aileron has ribs evenly separated, except the end rib, which for some reason is placed at twice the separation than the rest. I am guessing that this left the tip vulnerable to bending by the fabric pressure.  Our solution was to add another rib and an end plate before the re-fabric work.  So far it seems to be holding well, except for a little rubbing with a small spot on the plywood that covers the end of the wing. (our solution for this, was to file away the plywood "tip" )

As I mentioned before, we used Stewart Systems Ekobond as our adhesive and it has worked quite well, with the added benefit that it is easy to work on and a no "nasty fumes" chemical.

After the fabric work, a hand of Dope paint was applied and soon after a second hand with aluminum so to protect the fabric from UV.

At this point, the only thing missing is the cosmetic paint cover, to make the aircraft look good.

I am expecting that tomorrow , we might be able to give it a first tow to see how it behaves.

I will keep you posted!

Fabric time

Another week of work and we are making lots of progress.

Yesterday we finished the ailerons cabling, leaving the plane ready for fabric covering.

Gamal showing me how to apply anti-chafe tape

To cover a surface is not very difficult, but requires experienced hands to do a good job. Luckily we got our friend Gamal to give us a hand on it.

You start by cleaning all surfaces where you will be placing the adhesive and apply anti-chafe tape to prevent metal to cut through the fabric.

Cutting fabric

After the surface is ready you apply the fabric adhesive.  For this proyect we selected Stewert Sytems Eko-Bond adhesive mainly because it is a water based latex, so I had no problem bring it from the US on my checked in baggage.. Had customs asked about it, I was ready to say it is a new brand of hair shampoo :)

Applying the adhesive is quite easy, just "paint" a thin film of it and wait till it get sticky before placing the fabric on top.  ( a great video tutorial can be found At Stewart Systems youtube channel )

Applying the top layer of  fabric adhesive

Once the adhesive has cured, heat is applied to shrink the fabric to eliminate imperfections. Again, the process is not hard, but you need skill to do it right. I'll say it is more an art than a science. 

Water based adhesive, really nice to work with.

Gamal & Juan heat activating the sealant

Covered wing, ready for Aircraft dope

A good days work got us two wings covered and the prep work for the rest of the surfaces.

This week we should be finishing that and applying aircraft dope. With a bit of luck , the plane may be ready to test by next week.

All about cabling

Knowing how important is to properly set up the aircraft cabling, We recruited the help of our good friend Gamal Casas to help out in the process. Here in Peru, Gamal is sort of a legend among ultralight builders as he has assembled most of the flying ultralights in the region.

I've personally flew the first flight of the last Challenger ultralight he assembled, it flew hands off since the first run.

First we put together the GOAT and checked for symmetry between the wings and the fuselage.  To do this, we first installed the flaps and the ailerons with a few soft rivets to keep them in place. (We will remove those to fabric afterwards)

With that done, we measured and cut the structural cables to size, before assembling them with it's sleeves and nicos. Originally, the kit came with out any shackles. We decided to add them at on the main wings to make it easier to assemble and dis-assemble the kit for transport.  (Otherwise, it would have required the removal of bolts on the tail and nose every time)

Getting cables right is a slow and detailed process, always stopping to double check the symmetry of the structure and making sure the previous cable did not throw the alignment off.

We started with the tail section, and quickly found that  bottom cable connecting attachment was missing. I emailed Jon in NY who quickly replied with pictures of the prototype. With this Gamal was able to find a replacement from parts we had in the shop.

Tail bottom wires

Tail top wires

Wing to tail cables

Modified wing cable attachment point

The original cable attachment piece on the trailing edge of the main wing seemed to be a bit short in comparison to what we saw on the pictures, so we built a larger one to accommodate the for the flap angle.

Rear cables view

Rear cable split view

On the wing front cable attachments we added shackles for quick dis-assembly

Wing to nose cable

New rear cable attachment point with shackle for easy dis-assembly

Completed the structural cabling, we started the controls cables wiring with the pedals and rudder controls.

For this process we clamped the ailerons and tail surfaces in their middle position, then centered the pedals and the flight stick before clamping them too.

Once everything was in place, we cut and assembled the wires making sure that the control surfaces had proper travel 

Rudder controls view 2

Rudder controls

Pedals

Rudder pedals

Rudder pedals (springs located temporarily)

We paid particular attention to the ruder controls, as the ruder surface is quite large and did not wanted to allow over controlling of it.

Finally we routed the cables through the wing ribs by carefully wrapping the tense control cable with a piece of coarse sand paper (coarse side facing out of course) and sliding back and front till the tension disappeared.

Again, we put shackles on the cables so we could quickly dis-assemble the wings when needed. 

Control stick cabling

Cable routing through the ribs

Some dude posing as a pilot :) 

Weekend Update

This was a busy week!  We discovered some of the aluminum tubes where starting to build sulfate, so we decided to go ahead and zinc paint *everything*

Lots of work, one wing was pretty much done , the other had most ribs still missing, so starting Monday I had to wrap all the ribs with craft paper so the thinner wouldn't get to them. Tuesday I  painted the fuselage, the struts, the pedals.  Wednesday off, had to fly to paracas, Thursday finishing up  painting details.

Friday, a friend from Miami Fl, sent me 3 rolls of  fiberglass threaded tape (the same that came with the kit) and 3M aluminum tape. With this we where ready to assemble the rest of the ribs and get ready for 1st full assembly.

The flight club on Sunday's is usually quite busy, so we did not made a lot of work, but we managed to put the plane together with the wings finally ready. (also had an awesome meal cooked for all by our  latest student to solo. )

Tomorrow we will install the flaps and place the ailerons up with soft rivets so we can measure all control cables. (probably install the pedals and the seat too)

Finishing last details by the headlights of my truck

All about ribs

Today we spent the whole day working and made quite a bit of progress. 

First, we finished gluing the ribs and the corner edges through the ribs by shaving the inside of specific ribs .

A & B ribs shaved to fit the drag spar

After that, we riveted the few parts still being held by clecos and finally we covered the glued ribs with the aluminum tape.

Drag Spar in place

Close up of the taping 

Wing end corners

Another view of a corner 

The process is not hard but it is quite time consuming. 

To get a wing done we used three rolls of the fiberglass lined adhesive tape and almost two of the aluminum tape. This means i'll be short 2 rolls of the fiberglass and one of the Aluminum.. I've looked for it everywhere with no luck, so, I guess I'll have to get it imported from the US...

*Luckily some friends are coming to visit us for turkey day.. hopefully they'll bring me some.

finished with one wing and waiting for parts to do the next

Finished wing edge

Compresion tube suport 

Compression tube and aileron control mechanism

Completed wing

Gluing the ribs

Continuing with the wing assembly, yesterday we began the process of setting the foam ribs in place.

As described by the kit instructions, we start by applying a thin layer of Gorilla glue (previously mixed with water) on each end. Then, after setting them in place we wrapped them around with fiber glass tape. Gorilla glue expands quite a bit, so it is key to place *and tape* one rib at a time, otherwise you run the risk that the expanding glue will shift things around. The roaster jig that mike suggested we built for the wing, helped a lot in the rib setting process.

After the first set of ribs was in place, we decided to place the the drag strut diagonally through the rib holes.  We carefully shaved the rib's holes on the inside, just enough to allow the drug strut to fit in place with out bending any of the ribs.

By the end of the day , we finished the first section with pretty good results. All in all , the process is not difficult, it just takes a little patience to get the ribs placed right.

First section glued and tape wrapped

To be honest, the hardest part was to handle the amount of on lookers that kept dropping by, to chat and check things out !

See you next week!

Give me wings !

Continuing with the assembly of the goat, yesterday I put together the left wing according to the instructions sent by Michael. The instructions are no more than a page of basic instructions (no pictures).

Using the original Mike Sandling goat 1 drawings I was able to figure out most of the assembly. The few things that left me puzzled where answered by Michael (via Jon) that same afternoon.

There are a few differences between the original and this Super Goat. One is that the X shaped drag cables on the first section of the wing, have been replaced by a single drag tube. Another is that the second set of drag cables (the one on the second section of the wing) are gone altogether! I am guessing that the new style of rigid foam ribs will give good structural integrity to the assembled wing. The new style ribs are made out of a foam board called Pactiv Extruded Polystyrene Foam Board Insulation. I looked at the material info on them and they seem to have pretty good compression resistance. the way they are   installed is glued *and* wrapped by fiberglass and aluminum tape. I am pretty sure this should create a pretty good strength against expansion.

We also assembled and tested the rotissery wood setup made to help install the ribs (neat!)

Time ran out, so we stored the wing as it was (all put together with clecos ) on the hanger, and left for lunch. Tomorrow I will be testing the fabric glue and the ribs glue to see ho that works.