Jim.Thompson's blog View Details
Posted by Jim.Thompson | Sep 16, 2011 @ 02:45 AM | 4,392 Views
After reading this thread:https://www.rcgroups.com/forums/show....php?t=1506575 I have had further thoughts re. my wing moulds. I like the idea of steel reo, and always have. Adam describes how the glass can be balanced either side of the steel frame which avoids any likelyhood of warping due to CTE differences which apparently are very small anyway.
I am trying to find a source of Poraver beads, but if I cannot get some, will use sand or crusher dust as recommended.
It appear to be a very stiff and economical mould making method. I like it.

Jim.
Posted by Jim.Thompson | Sep 14, 2011 @ 05:00 PM | 4,529 Views
I am now sanding and surfacing up the plugs. The very best tools for this job are the long sanding boards as suggested by Larrikin Dave. The enable all the waviness to be eliminated with many fill/sand cycles. It helps to place the plugs in differing light conditions to show up the slight imperfections.

I have meanwhile started a wing joiner bar mould. I am making it as an epoxy surfaced and plaster backed mould. This will serve as a trial for the main wing moulds which I plan to employ the same combination. I have incorporated several layer of light glass cloth after the usual tooling/surface coat to strengthen the face coat. The finally a coupling coat of epoxy and a dust with cotton flock before allowing to cure for at least 3 or 4 days.
Posted by Jim.Thompson | Sep 09, 2011 @ 08:03 PM | 5,255 Views
The wing plugs are being primed and surfaced. I've made the parting boards to suit and they just need some fine adjustment and finally some splooge on the LE. I'll do this after painting them using cling wrap like Larrikin Dave did on his build log.
Posted by Jim.Thompson | Sep 01, 2011 @ 11:24 PM | 3,787 Views
I have decided to build hollow moulded wings for this plank, inspired to some extent by Dave's (Larrikin) build log -https://www.rcgroups.com/forums/showthread.php?t=1461579 .
This will be my first adventure into fully hollow moulding.
I have carefully cut the foam cores and have vacuum bagged them with 2 layers of 185 gsm 4H glass. They are still in the mylars. I will strip them tomorrow and get started with the parting boards before surface priming them.
The plans are to do an epoxy surfaced plaster mould. This disscussion going on the other thread : https://www.rcgroups.com/forums/show....php?t=1485623 is helping me make a choice of combinations in this regard.

More later,

Jim.
Posted by Jim.Thompson | Aug 24, 2011 @ 06:15 PM | 3,896 Views
I just cracked open the mould and pulled the first useable part from the plank mould! Overall, its very good if a bit heavy, but that does not matter. The fin seam is fine, the bladder came out of the fin except for a little bit in the LE. The fin is rigid - I reinforced it with spread carbon tow arranged in a cross pattern. I spead the tow on a rack, pics of which I will post later.
The only slight adjustment I will make is to the canopy opening as it is not quite symmetrical. Easy fixed by trimming one of the spacer halves before pulling the next part.
This one is four layers of 100gsm plain weave cloth. I think 3 would have done it, but I am aiming at a heavy plank, so no real penalty to have the heavier one. There is plenty of carbon tow in the fuse as well, four runs of 50k, spread as above.
Posted by Jim.Thompson | Aug 23, 2011 @ 04:09 AM | 3,800 Views
I have now successfully made the canopy mould and made some canopies from it.
The mould is nice and cured now and I'm preparing to do a fuselage lay up. I cut out the glass today, the layup will be four layers of 100 gsm plain weave glass cloth with a doubler on the front half. I will add four runs of carbon tow in the fuse with some in the fin to stiffen it up a bit.
Presently waxing up the mould and hoping for some dryer weather. We are experiencing yet more very wet weather.
I'm now toying with the
idea of building moulded wings for this one, based on the flying success of the prototype. These will be my first attempt at moulded wings. I will cut foam cores and vac bag them. Then they will be very carefully primed, sanded and surfaced up using external airfoil templates as a guide and using long sanding blocks.
Finally, I will probably spray them with 2 pack paint prior to setting them into a parting board. The first mould will possibly be done with a product called "Trowel On" as a thick surface coat. Then I will back it up with either plaster or an expanding PU foam.
Currently, "Emufingers" is conducting experiments on the above products.

Jim.
Posted by Jim.Thompson | Aug 02, 2011 @ 06:22 PM | 4,081 Views
I have now pulled the first part from the repaired mould. No canopy or openings, so this one will not be used.
I am now using the part to make a canopy mould from. When that has aged enough, I will make some conopies and spacers ready to make my first useable fuselage from.

Jim.
Posted by Jim.Thompson | Jul 04, 2011 @ 04:08 PM | 3,918 Views
I am now waxing up both new mould halves. After the usual 4 or 5 coats of wax I will flood and drain it with PVA. Then I plan to do a sacrificial pull on the damaged half. I will use a surface coat and let it green off in the usual way, and then lay up some veil which I have in stock and otherwise no longer use. Several layers will give it sufficient stiffness to "pull" out of the mould intact. That is providing I have achieved a good release. This will be the proving of success the mould repair, or otherwise.
Posted by Jim.Thompson | Jul 02, 2011 @ 05:48 AM | 4,306 Views
I have now built the mould and allowed one week for it to cure and stabilise. I split it to remove the plug which came out of the second half without much difficulty. There were just a few pieces of gel coat off the plug which stuck to the mould around the wing fillet areas. I expected this.
However, the first made half stuck like it was meant to. It required total destruction to remove it and along the way, I damaged the mould half rather badly.
However, I have repaired it over the last week or ten days piece by piece. First of all, I cleaned it thoroughly with water and then acetone. I then ground out any cracks and deep gouged, first filling with vinylester tooling "Q" cells mix. Several applications were applied, sanding in between. Then I surfaced it with a surface coat of the tooling resin and graphite/Wests 403 mix. Sanded finally with fine 320 grit paper.

Today I mixed some 2 pack casting silicone and poured the wing fillet inserts.
Tomorrow I plan to begin waxing up. Then I will apply PVA by the "Flood and drain" method. When it is dry, I'll do a sacrificial light layup with some light glass. I want to do this to prove the release capability of the repaired surface before commiting to a complete fuselage layup. The repaired mould is all I have left of the shape that took so much work to shape. I have the original mould, but the shape has been very slightly improved in symmetry etc. since it was made. At worst, I could make a plug from this, reshape and build another complete mould. But I am hoping that it will not come to that.

Jim.
Posted by Jim.Thompson | Jun 09, 2011 @ 11:20 PM | 4,085 Views
I finally have my new revised plank plug and parting board ready for PVA and then first mould half. It has about 5 coats of wax as seen in the picture. Along the way, I had a house breakin and the kid damaged the plug by spearing it into the ground. Fortunately, it did not do much damage, and I was able to repair it reasonably easy. The police found the kid and return other stolen goods!
Posted by Jim.Thompson | May 01, 2011 @ 03:26 AM | 5,243 Views
The shaping and surfacing of the plug is nearing completion. It is quite a challenge to keep the wing fillets geometry correct and to maintain the sharp arris where the part will meet the wing.
I have started to cut out the parting board.
Posted by Jim.Thompson | Apr 23, 2011 @ 04:20 AM | 3,720 Views
I'm now surfacing and sanding the plug. I use polyester resin mixed with "Q" cells and "wax in styrene". This is brushed on and sanded with 40 grit paper dry to start with. After first couple of coats or so, I then wet sand between coats with 80 grit wet and dry paper.

This is in preparation for spraying with polyester gel coat.
Posted by Jim.Thompson | Apr 18, 2011 @ 03:43 AM | 4,498 Views
My recently built PW51 plank has flown many time now and is such a success that I am developing the plug to include the fin and fillets. I'm make a new mould from this. The final model will be a 2 part wing, my first.

The pictures tell the story, but a few details might help to explain how I went about it.
I made the fin by hot wire cutting a symmetrical (SD8020) blue foam core and gluing pre made skins onto it in the usual fashion. Wooden tips and LE were then added and shaped. I then PU glued it to the old plug.
For the wing fillets I went about it like this: I printed out several profiles of the airfoils on Profili2 and cut some 10mm thick Douglas Fir to the shape. These were glued onto the plug using the jig system in the pictures. I also cut out some formica profiles which are hot glued to the outside of the wood. These are intended to protect the arris on the end of the fillets during the sanding and filling process. To get them square with the fin, a 5mm locating hole was drilled in both sides and a larger one drilled through the main body of the plug to take the 5mm carbon tube. Everything was set up on a level surface and a plumb bob was used to get the fin/body vertical.
I also used the tube to ensure the fillets were square to the centreline of the body.
The last thing to check was that the fillets were parallel.
The two sandwiching boards clamped the assembly and were adjusted to be both parallel with each other and parallel with the centreline.

I then cut some small LE and TE gussets out of some 1.5mm ply. These were glued in to provide screeding stops for the splooge infill.
The last picture is the polyester/"Q" cells/wax in styrene filler roughly applied waiting to go off prior to sanding.

Jim.
Posted by Jim.Thompson | Apr 01, 2010 @ 06:51 PM | 4,745 Views
I have just stripped down my double taper wing for the new "Endorphin Rush" bagged in one piece. This is my first attempt at bagging a wing this size in once piece, and it turned out fine.

After some discussion with Sean Moloney is about to tackle an even bigger one (see his blog), I decided on buying a and using the FGI nylon vac bag material and tacky tape. "Tacky Tape" is the trade name, and it is a bit like blue tack and thick butyl mastic. The combination worked very well.

I hope the pics will describe the proceedure. Some carefull forward planning made it straight forward actually. I would do the same again.

Very pleasing result!

Jim.
Posted by Jim.Thompson | Mar 22, 2010 @ 08:27 PM | 4,794 Views
My new "Endorphin" is now trimmed and sorted. The brakes work so well, I had to reduce the deflection of the flaps to around 65 deg. To adjust the down elevator compensation, I selected the programmable mixer on the tx. before launch. I could then adjust it while flying, by bring the tx up close to my face while the plane was high and safe.
I have it trimmed nicely for all modes of flight. In the dive test, it stays on the set trajectory straight and true.
It will fly basic manouvres smoothly, but not too good on inverted flight, which is not surprising.

Very pleased with this plane!

Jim.
Posted by Jim.Thompson | Mar 08, 2010 @ 07:03 PM | 6,206 Views
The new rebuilt Endorphin is finished. I followed some suggestions from Steve Wenban regarding a couple of minor mods.
I changed the tip airfoil to E205 with the foot foil the same SD6060. This was to make it more manageable to suit my level of flying skills. I also built in a small amount of dihedral.
I have flown it, and it is mostly sorted. It satisfies all expectations, and the butterfly braking slows it donw to a hear hover for very safe, controlled landings. I'm really delighted with it!

I have already started another one, this time with the original symmetrical SD8020 on the tips. Also, it will have a double taper and more modern rounded tip LE.

More as build progress continues.

Jim.
Posted by Jim.Thompson | Jun 27, 2009 @ 12:59 AM | 4,922 Views
My recently built "V" tail was maidened at the Mt. Bora NSW Australia recon weekend early this month. I have posted info abou this, so will not add too much. It was one of my first composites, and eventuated over weight at 1.7 kgs. At 1800 mm, it flew (not surprisingly) very fast, much too fast for my limited experience.

I see it now as a successful prototype, and work has started on the new one which will be called: "Endorphin". Much lighter and with a more docile airfoil. The prototype had a blended airfoil, with a SD606 at the root, and a symmetrcial SD8020 at the tip.

More as this plane develops.

Jim.
Posted by Jim.Thompson | May 02, 2009 @ 12:49 PM | 4,553 Views
Ok. So I have found the way to make a post on my blog!
I started flying models when I was a teenager four decades ago, flying control line aircraft, freeflight and then single channel radio control. For those younger readers out there, these primitive planes had rubber powered escapements which we wound up with a hand drill, and rudder only. This meant that the nose dipped of the plane each time a command whas given. It was one click of a button for say left, and two for right. The escapement had to go through left to get to right. Or vise/versa. In hindsight, I do no know why it was not customary to link the rudder and elevator mechanically to provide slight up when the rudder was activated. It would have provided a more balanced turn.
After over forty years abscence from flying, I was drawn into it again after a visit to my brother in New Zealand who has been an active rc modeller (again) for decades, whith his own magnificent slope on Waiheke Island. Also, a previous employer of mine gave me a built up thermal glider, which I eventually cut down the wing and fitted ailerons to make it into a slope glider aileron trainer. I learned to fly on the slope with it, and it has been crashed numerous time. Its been in trees, in the ocean and flown at great speed through a barbed wire fence.
Recently, I have been learning to build composities, so effecient! I am currently building three models of my own design. Actually, only two now, as the plank is ready to go!

More later............


Jim.