He came over last weekend and did a training day with me.
Reinforcing the joints on a test piece I made. It turned out very good.
I think he will order a kit soon!
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| Johan cutting out fabric with the rotary cutter |
Wednesday, 8 August 2012
Another Twister fan
Say hi to Johan from Belgium.
He came over last weekend and did a training day with me.
Reinforcing the joints on a test piece I made. It turned out very good.
I think he will order a kit soon!
He came over last weekend and did a training day with me.
Reinforcing the joints on a test piece I made. It turned out very good.
I think he will order a kit soon!
Week 52 - Gear align and fuse reinforce
Hours to date: 464.25
Finally got the gear aligned to my satisfaction - as you will see from the below photos they are both exactly 0.25 degrees toe out - perfect!
While on the subject of gear I thought I would let you know that I found one of the gear leg holes made for the axle to be too big on one side of the hole. This allowed for a little play and I was not at all happy about this, even though the axle gets bolted to the gear leg, that little play was unacceptable to me.
So how to fix it?
I had a scrap piece of axle - that is trimmed off (see photo) so the the axle is flush with the edge of the gear leg. So I put 3 layers of mould release wax on this and then flocked in the hole - using this piece of axle to make a perfect fit for the hole. Some flock was pushed in around the edge - you can see from one photo below that quite a bit was needed - it is the lighter coloured material just on the edge of the hole.
When it was all cured I was a touch nervous that the axle would not come out - but it came out easily with a few gentle taps with a socket of the right size and rubber mallet.
The axle now fits perfectly - no play at all.
This week I've started on reinforcing the fuselage seams - just done the top so far.
On the weekend I hope to start on the inside of the fin - there are two carbon sandwich brackets that need bonding in there - to do this job I will need to have the garage door open - so I hope it is a nice day.
Finally got the gear aligned to my satisfaction - as you will see from the below photos they are both exactly 0.25 degrees toe out - perfect!
While on the subject of gear I thought I would let you know that I found one of the gear leg holes made for the axle to be too big on one side of the hole. This allowed for a little play and I was not at all happy about this, even though the axle gets bolted to the gear leg, that little play was unacceptable to me.
So how to fix it?
I had a scrap piece of axle - that is trimmed off (see photo) so the the axle is flush with the edge of the gear leg. So I put 3 layers of mould release wax on this and then flocked in the hole - using this piece of axle to make a perfect fit for the hole. Some flock was pushed in around the edge - you can see from one photo below that quite a bit was needed - it is the lighter coloured material just on the edge of the hole.
When it was all cured I was a touch nervous that the axle would not come out - but it came out easily with a few gentle taps with a socket of the right size and rubber mallet.
The axle now fits perfectly - no play at all.
This week I've started on reinforcing the fuselage seams - just done the top so far.
On the weekend I hope to start on the inside of the fin - there are two carbon sandwich brackets that need bonding in there - to do this job I will need to have the garage door open - so I hope it is a nice day.
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| Port gear - perfect |
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| Starboard gear - ditto |
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| Scrap axle off cut I used for gear hole fix |
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| Flock is lighter coloured around edge of axle |
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| Fuselage - reinforcing the seam |
Tuesday, 7 August 2012
Getting in on the display act
I see Adrian Hatton in his fixed gear Twister is doing displays now too.
Link to his site here:
http://www.twisterairdisplays.co.uk/
I know Adrian as he used to do the CofA on our glider.
Link to his site here:
http://www.twisterairdisplays.co.uk/
I know Adrian as he used to do the CofA on our glider.
Sunday, 29 July 2012
Week 51 - Gear align and setting Dihedral
Hours to date: 452.75
I haven't got much done since the last post. Visitor staying with me and I went to the Olympics yesterday - to watch the Cycling Road Race.
As far as the gear alignment goes I think I am there now. I used a laser level to cross check my previous work with the string and it turns out that the string gives a pretty accurate measurement.
The error was less than 0.1 of a degree - that was on the starboard side and on the port side it was a little more (I kind of knew this would be the case with the port side as I added a tad too much plywood to that one). So I've taken both the plywood blocks off again and got them to where I think they should be perfect.
The other thing that I've done is drill out the 8mm hole in the gear legs and axles so that they can be attached with the allen bolt and made rigid - there was room for play before. I still have to fit the brakes to the axles but this can be done later.
Another job that needs to be done is making sure that the gear has the right amount of dihedral.
To do this I had to build a little contraption out of wood and a steel tube. See pic below.
I've just tacked the plywood blocks back in place and will do a final-final alignment and dihedral check before they are completely bonded in place.
I haven't got much done since the last post. Visitor staying with me and I went to the Olympics yesterday - to watch the Cycling Road Race.
As far as the gear alignment goes I think I am there now. I used a laser level to cross check my previous work with the string and it turns out that the string gives a pretty accurate measurement.
The error was less than 0.1 of a degree - that was on the starboard side and on the port side it was a little more (I kind of knew this would be the case with the port side as I added a tad too much plywood to that one). So I've taken both the plywood blocks off again and got them to where I think they should be perfect.
The other thing that I've done is drill out the 8mm hole in the gear legs and axles so that they can be attached with the allen bolt and made rigid - there was room for play before. I still have to fit the brakes to the axles but this can be done later.
Another job that needs to be done is making sure that the gear has the right amount of dihedral.
To do this I had to build a little contraption out of wood and a steel tube. See pic below.
I've just tacked the plywood blocks back in place and will do a final-final alignment and dihedral check before they are completely bonded in place.
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| Axle bolted to gear leg. |
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| Laser level check |
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| Dihedral setting rig |
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| Bar is bent to 60mm above floor to set dihedral |
Sunday, 15 July 2012
Week 50 - Gear align and spar tunnel
Hours to date: 438.0
A fairly good day in the workshop today.
Managed to get the gear legs aligned to 0.25 degrees toe-out. I had to take off 10mm on the Port, and add 8mm to the Starboard gear plywood brackets to get them both the same alignment.
With the plywood brackets removed I was able to finish the spar tunnel to safety cell reinforcing with carbon.
Next thing to do is put the plywood brackets back in place - I will just tack them in place with flock to start with. Then check the gear legs again (getting paranoid here) before fully flocking and glassing the plywood brackets in permanently.
On Friday I went to Farnborough. They now no longer have the trade halls open on the Public days (Sat and Sun), but release some special tickets for the Friday which I was able to get - so I had a good look at all the new tech on offer. Pretty interesting to see the Skylon stand with there prototype Sabre engine - the future of space travel? More about Skylon here: http://www.reactionengines.co.uk/space_skylon.html
Some pics that I took on this link: http://www.flickr.com//photos/andymac53/sets/72157630571936142/show/
A fairly good day in the workshop today.
Managed to get the gear legs aligned to 0.25 degrees toe-out. I had to take off 10mm on the Port, and add 8mm to the Starboard gear plywood brackets to get them both the same alignment.
With the plywood brackets removed I was able to finish the spar tunnel to safety cell reinforcing with carbon.
Next thing to do is put the plywood brackets back in place - I will just tack them in place with flock to start with. Then check the gear legs again (getting paranoid here) before fully flocking and glassing the plywood brackets in permanently.
On Friday I went to Farnborough. They now no longer have the trade halls open on the Public days (Sat and Sun), but release some special tickets for the Friday which I was able to get - so I had a good look at all the new tech on offer. Pretty interesting to see the Skylon stand with there prototype Sabre engine - the future of space travel? More about Skylon here: http://www.reactionengines.co.uk/space_skylon.html
Some pics that I took on this link: http://www.flickr.com//photos/andymac53/sets/72157630571936142/show/
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| Final bit of spar tunnel to safety cell reinforcing |
Tuesday, 10 July 2012
Week 49 - Main gear alignment
Hours to date: 431.5
I spent most of Saturday checking the main gear alignment.
I started by bolting the gear in place - the aluminium bars that go over the gear and hold it in place need radiator hose (30mm works well) over the parts where they would touch the gear legs. They also have 1mm thick rubber sheet underneath between the gear leg and flock mounting block.
Then I just measured the distance between the wheel hubs, found the centreline a good way back on the fuselage - over 2 metres back - and then measured out from there half way with an old broom handle as a straight edge.
I then used string from the wheel hub face all the way back to the broom handle and kept moving it until it was in a perfect straight line with the hub face.
Turns out the Port gear was indeed Toe out - by 4cm at 210cm distance. I then found an angle calculator tool on the internet which made it a breeze to find out, from the two values I knew, what the angle was. It was 1.07 degrees for the Port gear. So I need to alter that as I am shooting for 0.25 of a degree toe out.
On the Starboard gear it was a different story with that being Toe in. By 0.4 of a degree. So both gear leg brackets will need to be moved.
I'm not sure why the factory flocked them on there in the first place - the manual shows these not being in place as supplied.
As you can see from the final photo the holes in the wooden brackets are in very different places. I still haven't figured out if there is a smart way to know how much to move these brackets by to achieve the desired toe out - hopefully I'll have a brainwave before I do this or just go back to the string method if all else fails.
Also as a result of doing this job I found out that the wheel axles I have been supplied have be made wrong. There is a flange that is welded on the axle and I am certain it is in the wrong place. I've contacted the Silence factory to see what they say.
UPDATE: It turns out the axles are fine - it just that the wheels are the wrong size. So the wheel supplier will be sending me two new wheels soon. Sorted.
On Sunday I had another break from the kit to go to the world's largest military airshow - The Royal International Air Tattoo - at RAF Fairford. A brilliant show as always with lots of aircraft I had not seen before and top class flying by all.
Some pics here: http://www.flickr.com//photos/andymac53/sets/72157630509985102/show/
I spent most of Saturday checking the main gear alignment.
I started by bolting the gear in place - the aluminium bars that go over the gear and hold it in place need radiator hose (30mm works well) over the parts where they would touch the gear legs. They also have 1mm thick rubber sheet underneath between the gear leg and flock mounting block.
Then I just measured the distance between the wheel hubs, found the centreline a good way back on the fuselage - over 2 metres back - and then measured out from there half way with an old broom handle as a straight edge.
I then used string from the wheel hub face all the way back to the broom handle and kept moving it until it was in a perfect straight line with the hub face.
Turns out the Port gear was indeed Toe out - by 4cm at 210cm distance. I then found an angle calculator tool on the internet which made it a breeze to find out, from the two values I knew, what the angle was. It was 1.07 degrees for the Port gear. So I need to alter that as I am shooting for 0.25 of a degree toe out.
On the Starboard gear it was a different story with that being Toe in. By 0.4 of a degree. So both gear leg brackets will need to be moved.
I'm not sure why the factory flocked them on there in the first place - the manual shows these not being in place as supplied.
As you can see from the final photo the holes in the wooden brackets are in very different places. I still haven't figured out if there is a smart way to know how much to move these brackets by to achieve the desired toe out - hopefully I'll have a brainwave before I do this or just go back to the string method if all else fails.
Also as a result of doing this job I found out that the wheel axles I have been supplied have be made wrong. There is a flange that is welded on the axle and I am certain it is in the wrong place. I've contacted the Silence factory to see what they say.
UPDATE: It turns out the axles are fine - it just that the wheels are the wrong size. So the wheel supplier will be sending me two new wheels soon. Sorted.
On Sunday I had another break from the kit to go to the world's largest military airshow - The Royal International Air Tattoo - at RAF Fairford. A brilliant show as always with lots of aircraft I had not seen before and top class flying by all.
Some pics here: http://www.flickr.com//photos/andymac53/sets/72157630509985102/show/
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| Gear with rubber hose |
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| Establishing gear alignment |
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| Plywood brackets - holes are in quite different positions to each other |
Friday, 6 July 2012
Week 48 - Spar tunnel and Oil cooler
Hours to date: 425.0
It's been a lazy couple of weeks - busy at work and then going to Goodwood for the Festival of Speed.
Pics of Goowood here for the petrol heads amongst us: http://www.flickr.com//photos/andymac53/sets/72157630401758498/show/
Anyway I did manage to get some more of the spar tunnel reinforcing done. Just one area left to do at the front underneath - but I will leave this until I have determined that the wooden main gear brackets put in place by the factory are in exactly the right place.
Taildraggers must have the main gear parallel to each other and in line with the direction of travel. Either that or up to 0.5 of a degree toe-out. If they are at all toe-in then a very squirrelly aircraft is what you will have. I'll be aiming for maybe a 0.25 degree toe-out.
I've also got both seat belt reinforcements covered with carbon now.
Now onto the oil cooler.
Being that my kit is a fixed gear version I discovered that there is a large space in between the safety cell and the wing root that is normally taken up by the main gear. This space will allow for a much more efficient set up of the oil cooler - there is ample room for ducting in there to achieve maximum efficiency with the minimum of drag.
The area under the wing is also an area of high pressure - good for the intake and the exit duct will be a simple slot further back on the wing. I will also add a cowl flap on the exit to give some control over the temps (on the ground and in the climb I see this flap being open - but closed in the cruise - much as a P-51 radiator set up is.)
I will copy the F-1 McLaren’s F-Duct for a ram air inlet - sat a little way up to avoid the boundary layer of stagnent air that is close to any skin surface. McLaren know a thing or two about aerodynamics!
I've contacted the UL Power factory and asked them about the extra long hoses and if they see that as a problem. They responded by saying it shouldn't be a problem but advised to use larger diameter hoses to minimise the pressure drop. They also recommended just a 13 row oil cooler as sufficient for cooling. I know Pete uses a 19 row so I will go for a 16 row - just to be on the safe side.
Because of moving the oil cooler away from under the cowl, the cowling will therefore be able to follow the profile of the sump and should look much prettier than Pete's setup - as well as being much more streamlined.
I'm off to Fairford tomorrow for the Royal International Air Tattoo - the worlds biggest military airshow. Should be good, a few new aircraft and display teams I have not seen before.
It's been a lazy couple of weeks - busy at work and then going to Goodwood for the Festival of Speed.
Pics of Goowood here for the petrol heads amongst us: http://www.flickr.com//photos/andymac53/sets/72157630401758498/show/
Anyway I did manage to get some more of the spar tunnel reinforcing done. Just one area left to do at the front underneath - but I will leave this until I have determined that the wooden main gear brackets put in place by the factory are in exactly the right place.
Taildraggers must have the main gear parallel to each other and in line with the direction of travel. Either that or up to 0.5 of a degree toe-out. If they are at all toe-in then a very squirrelly aircraft is what you will have. I'll be aiming for maybe a 0.25 degree toe-out.
I've also got both seat belt reinforcements covered with carbon now.
Now onto the oil cooler.
Being that my kit is a fixed gear version I discovered that there is a large space in between the safety cell and the wing root that is normally taken up by the main gear. This space will allow for a much more efficient set up of the oil cooler - there is ample room for ducting in there to achieve maximum efficiency with the minimum of drag.
The area under the wing is also an area of high pressure - good for the intake and the exit duct will be a simple slot further back on the wing. I will also add a cowl flap on the exit to give some control over the temps (on the ground and in the climb I see this flap being open - but closed in the cruise - much as a P-51 radiator set up is.)
I will copy the F-1 McLaren’s F-Duct for a ram air inlet - sat a little way up to avoid the boundary layer of stagnent air that is close to any skin surface. McLaren know a thing or two about aerodynamics!
I've contacted the UL Power factory and asked them about the extra long hoses and if they see that as a problem. They responded by saying it shouldn't be a problem but advised to use larger diameter hoses to minimise the pressure drop. They also recommended just a 13 row oil cooler as sufficient for cooling. I know Pete uses a 19 row so I will go for a 16 row - just to be on the safe side.
Because of moving the oil cooler away from under the cowl, the cowling will therefore be able to follow the profile of the sump and should look much prettier than Pete's setup - as well as being much more streamlined.
I'm off to Fairford tomorrow for the Royal International Air Tattoo - the worlds biggest military airshow. Should be good, a few new aircraft and display teams I have not seen before.
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| McLaren F-duct |
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| Radiator theory - 1/6 opening is all that is needed |
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| Dummy oil cooler made out of foam for position check |
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| Pencil lines indicate oil cooler ducts and position |
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| Seat belt support reinforced with more carbon |
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| More spar tunnel reinforcing |
Sunday, 24 June 2012
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.
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.
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| Starboard outer and more carbon on seat belt block |
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| Inside of Starboard wing root to Spar tunnel |
Sunday, 17 June 2012
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.
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.
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| Spar tunnel to cell reinforcement |
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| Spar tunnel at wing root - before starting the job |
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| Job done. |
Monday, 11 June 2012
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.
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| Pedal position test |
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| Leg room just right now |
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| Cell mod complete - still got to tidy up and paint |
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| Gear leg position check |
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| Gear mount pre-reinforcement |
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| Post - with carbon |
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| 'Knees' of gear legs that need reinforcing |
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| Gel coat taken off and roughed up |
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| Roving in place |
Wednesday, 30 May 2012
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.
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.
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| Test piece bonding and after cutting |
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| Kevlar Shears |
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| Tacking in place with Flock |
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| Cardboard templates with aluminium tape |
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| 3 coats of wax helps them release from fabric |
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| Partly done. |
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| Almost there. |
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| Block needs to be made taller to fit Carbon bracket |
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| Cardboard to make micro assume the right shape |
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| With micro in place and drying |
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| Block done (pre layer of glass) |
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