Week 46 - Spar tunnel reinforce part 2

Hours to date: 418.75


Didn't get anything done during the week as I was very busy at work - late nights every evening.


Managed to get the Starboard outer and inner spar tunnel reinforcing done this weekend though.


Also after speaking to Pete he has recommended I put a strip of carbon over the wooden seat belt block. He said that he was very welcome of that extra strength during his crash with the first Twister.


Accident report here if you are interested in what happened.


http://www.aaib.gov.uk/publications/bulletins/november_2005/silence_twister__g_twst.cfm


Hopefully I can get the rest of the underside of the spar tunnel reinforced this week. Next weekend is busy for me as I am going to the Goodwood Festival of Speed - nice to have a break now and then.

Starboard outer and more carbon on seat belt block

Inside of Starboard wing root to Spar tunnel

Is it just me?

Or are these two getting closer these days?

Week 45 - Spar tunnel reinforcing

Hours to date: 412.25


Work this week was on the wing spar tunnel, which needs to be connected properly to the safety cell and fuselage.


This is done anywhere the two touch. I have done the inside and one wing root so far.


Nothing much to say about this job - pretty straight forward really. Just think about all the curves you have to go round and use several smaller pieces of carbon rather than going for one long strip each side - which would be a nightmare to work with.


The main new thing here was that I was using several layers of Carbon at once. And the weave must be offset by 45 degrees between each piece to give strength in every direction of load. 2 layers on the cell and 3 layers needed on the wing root. Each layer is 10mm less width so there is a smooth transition rather than a huge step.


Next job will be to flip over the fuse and do the other wing root and then the rest of the joins on the inside of the wing roots and the cell.

Spar tunnel to cell reinforcement

Spar tunnel at wing root - before starting the job

Job done.

Week 44 - Safety Cell mod - Part 4 and UC work

Hours to date 402.75

Finally finished the safety cell mod - well all the Kevlar is done - still got to pretty it up with some filler and paint - but that can wait till I am ready to paint the interior of the safety cell. What colour? Grey seems to be the popular choice. I'll most likely go for that.

As you can see from the below photo I can just touch the end of the cell with a pointed toe - so that should be well clear as the rudder control on full lock will not be that extreme a movement.

Next up I decided to tackle some of the main gear reinforcement - most of this will not apply to anyone building a retractable version.

The gear mounts have a layer of carbon on the inside and 4 metres of carbon roving wrapped around each 'knee'.

I hadn't worked with roving before but this job seemed to go okay. I cut each 4 metre piece into 1 m sections to make life easier. As you can see the 'knees' needed roughing up before applying the roving.

You can easily fill in any gaps in the windings with some spare carbon strips left over from other jobs (I knew these would come in handy!). Several can be wound together to form a thicker strip and easily bonded into place.

Next job may well be reinforcing the cell to wing spar box - which must be done inside and out with carbon.

Pedal position test

Leg room just right now

Cell mod complete - still got to tidy up and paint

Gear leg position check

Gear mount pre-reinforcement

Post - with carbon

'Knees' of gear legs that need reinforcing

Gel coat taken off and roughed up

Roving in place

Week 42 - Safety cell mod - Part 3

Hours to date: 382.0


Been working solidly on the cell mod for the last 2 weeks - the end is in sight now.


Had a little delay while I waited for some Kevlar Shears to arrive. I tried cutting the Kevlar with normal shears - no chance! Also the rotary cutter was defeated by this most strong material. The shears are not cheap at £28 - but essential for the job.


I started off by doing a test piece - to see if I could make a sandwich of honeycomb properly. This worked out very well and is incredibly strong even with just one layer of Kevlar on each side.


Next up I 'tacked' the front of the cell in exactly the right position using Flock. I used duct tape and pieces of wood to hold it in the right place while the flock set.


Then it was a case of making up templates in many sections out of cardboard, these were then covered with aluminium tape and given 3 coats of release wax. Taped in place these provided a perfect shape for the outer layer of Kevlar to assume when bonded.


Once the outer layer was set it was time to make up an inner layer that consisted of another layer of Kevlar on each side of honeycomb (Nomex), followed by peel ply.


If this sounds time consuming it's because it is!


It's worked out well though and when the pieces are overlapped the whole thing becomes very strong.


Almost done this now - just a few small fiddly pieces to go around the firewall support area. I will finish by putting another layer on all round of Kevlar - maybe even 3 layers on the part where my feet will be.


The other thing I've been working on is modifying the block that is bonded into the footwell and is the attachment point for the rudder pedals.


I had to change the angle of the back of it to match the new angle of the cell (a side effect of the mod). Also I found it needed to be made taller - by about 20mm to have the carbon bracket fit on it properly. I did all this with micro - as you will see from the photos - and finished up with a layer of glass (same as the factory had done).


Hopefully I will have finished the cell mod by the end of next weekend - which is a 4 day affair due to the Queens Jubilee and Bank holiday falling on consecutive days, Monday and Tuesday. I should be able to make some good progress.

Test piece bonding and after cutting

Kevlar Shears

Tacking in place with Flock

Cardboard templates with aluminium tape

3 coats of wax helps them release from fabric

Partly done.

Almost there.

Block needs to be made taller to fit Carbon bracket

Cardboard to make micro assume the right shape

With micro in place and drying

Block done (pre layer of glass)

Week 40 - Safety cell mod - Part 2

Hours to date: 352.5


Getting closer to bonding the safety cell mod but first there is a lot of prep work to be done and that's what has been taking up my time this week. Got a case of 'Sanders elbow' doing this.


I also spent quite a bit of time doing test runs with tape holding the front of the cell in the right position - my earlier calculations seem to be right. 5 inches at the base and 7 at the top. A side effect of changing the angle of the footwell is that the Micro block that the rudder pedals get attached to will have to be modified to sit flush at the right angle - easily done, just got to add more material to it.


Just as well I didn't order the BRS option on this kit - there would be no room for it. The space I am taking up with my mod is normally reserved for the Ballistic parachute and explosive charge.


I also bonded in the seatbelt reinforcement plywood blocks and sanded everything down smooth so nothing can chaff the belts. Still got to fill in the honeycomb with micro on that job.


Finally I made the top access hole in the fuselage a little larger so access will be easier for the cell mod.


Hopefully this week I can begin the bonding of new Kevlar and honeycomb to the front of the safety cell. This will be done in several stages - most likely a 'tacking' stage first with flock on the struts then once that is dry the outside layer of Kevlar followed by honeycomb in the void and then finally another layer of Kevlar on the inside.

Front of cell roughened up for bonding

Ditto at the other end and on the firewall support struts

Seatbelt reinforcement flocked in place and sanded

Upper access hole made bigger

Week 39 - Seat belts and Safety cell mod

Hours to date 343.25

Made some decent progress over the long Bank holiday weekend.


I took the plunge and cut the front off the Safety Cell. 


It will need extending by 5 inches at the base and 7 inches at the top. Such is the freaky nature of my long legs!


The upper part curves inward - hence the top being extended further - that way my toes won't hit the end when full lock with the rudder.


It was a bit of a mission to cut. Kevlar is super strong and destroys the Dremels cutting wheels. I went though my 2 best wheels and then about 12 of the cheaper cut off wheels. All in all took about 4 hours to mark and cut.


The weird shape of the cut is due to the safety cell being attached at the front lower portion by a huge amount of Micro. Rather than grind all that away I just went around it.


A further complication is the carbon reinforcing struts that come back from the firewall. They will get in the way of the front lower part of the safety cell when it is moved forward. So I will have to modify the shape of the cell in those areas to accommodate the Carbon struts.


I also cut out the lower and upper access holes - which are needed anyway - but needed now so I can work on the outside of the cell when I extend it.


I plan to attach the front of the cell temporarily in the right position with strips of plywood and 'bondo'. (A technique I learned from Mike Arnold on one of his videos). It's going to be a mission to do this mod - also I have no experience of working with Kevlar and have heard that it is hard to wet out properly. Still it's got to be done. Comfort in the cockpit is paramount!


Next up is the seat belts. The manual shows the two plywood reinforcement strips  already in place. Mine as you can see from the photos were not done. Studying the photo in the manual I saw that this area has been reinforced by carbon. So I've applied two strips to stiffen up this area and distribute the load some more. When that is dry I will add the plywood reinforcements with a load of Flock.

Micro at front of cell

Footwell of cell before marking or cutting

Bingo!

View through to firewall and carbon struts

Seat belt holes and reinforcing plywood - pre fitting

Plywood blocks now shaped to fit better to the cell

Carbon reinforcement - prior to bonding on plywood blocks

Lower access hole cut

Remnants of cutting wheels - Kevlar is tough stuff!

Fuselage dolly

Finally finished the fuselage dolly.

It took me a bit longer than planned as I wasn't feeling the best after suffering from another cold.

All done now and fits good.

I don't think the paint stand will work for the rear of the fuselage - it's too high - so I may have to build something for that. It will be pretty straight forward - just a mini saw horse type thing with maybe carpet or foam on top.

Hope to get this sorted soon and actually make some progress with the kit! It's been a while.

I'm thinking that one of the first jobs will be modifying the safety cell - so I have to determine by how much. While I'm thinking about it this will mean a lot of sitting in the cockpit and making plane noises...

Dolly partly made

All done - fits good

The great swap

Well not much has happened since I last posted.

I had my brother staying with me so didn't get much done (other than building the wing stand).

Also Pete stalled a bit on getting back to me about the wing swap and in the end told me he no longer has the room for storage.

So I ended up having to find a new place for the wings. Luckily my friend has space is his garage so the wings are there now.

The fuselage is in the garage okay but everything is a bit of mess at the moment - so I need to tidy up before starting any jobs.

First job after tidying up will most likely be to build a dolly for the front of the fuselage. I plan to put the rear on one of the paint stands and see how that goes. I may have to build a dolly for the rear fuselage - but for the moment we'll see how we get on without one.

Hope to build the front dolly this weekend.

Fuselage finally in the garage

What a mess

Week 33 - Wing stand

Finally got the wing stand finished - it took three times as long and cost twice as much as expected. This rule seems to hold true when building a plane (or boat).


Also thought I would put a couple of pics in of the plywood washers that I made for the bell crank. Pete turns a single piece out of Nylon block. I don't have a lathe (or those skills) so I made 2 separate pieces of plywood. All very snug and no movement in the bell cranks now.


I'll hopefully get to swap over the wings and fuselage during this Easter weekend.

Small washer in bearing

Then larger washer on top

Port wing - up to speed

Insulating foam in wing stands before cutting out

Wing stand in progress - one end nearly done

All done - now to see if the wings fit!

Wings fit very snug - no movement