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Baudis Model Trinity Introduction I was hankering for a new model just before Xmas, and stumbled across the Trinity whilst window-shopping German websites. A MG06 sectioned wing, at a substantially cheaper price tag than a Pike Brio, semi-justified the purchase of another 3m F3F model for the hangar. First Impressions Unwrapped, it turned out to be number 12 from the moulds (rather was close to being unlucky 13 for my liking) with a December build date. I haven't seen another Trinity to compare with, so I don't know whether the design and construction varies on later models. Mine came with carbon push rods, a sheet of lexan/polycarbonate bubbles for the servo linkages, and couple of spare screws; but no other fittings or a CofG The wing is in three fairly equal pieces, with slight dihedral at the wing seat and the centre panel to wingtip join. The control surfaces are around 30% of the chord as per Aeromod's original MG06 models. The full carbon/balsa version weighs in the region of 2800g before ballast; but lighter versions are available. The wing and tail layouts are definitely new-skool; curved leading edge and fairly straight trailing edge, leading into to swept back tips. It is pretty, but I prefer the old fashioned planforms ­ triple taper leading edge, and PikeWR/Tragi-style tips. In sharing the no-straight-lines approach of its baby brother, I think it should perhaps be re-titled as the "Big Banana".

First impressions were good. Paint depth is towards Samba-thin, showing off the construction and giving a functional appearance. Finish is tidy, accurate and sturdy. There's no sign of local epoxy and micro-balloon filling, like some Breta offerings. However, it's not in the Jaro Muller or Wizard Compact `thing of beauty' league. All the mouldings are accurate and true; no warps or twists. I found the hinging for one flap and one ruddervator shows a very slight misalignment at opposing ends of the control surface. Stiffness wise; in torsion the panels are excellent, but I don't think it's quite as stiff span wise as my Tragi PNS. I haven't sat on them in back to back test conditions though. All the control surfaces seem to be solid filled internally epoxy and micro-balloons, keeping their stiffness up and avoiding the need to locally fill for the control horns. On this carbon/balsa version the tailplane is glass skinned in the main, with heavy carbon reinforcement at the root and along the trailing edge for the last inch of the chord. This makes up for the lack of a sub-spar to support the extreme tips. The tailplane has two bolt holes, but no metal inserts. The holes were slightly oversize on my example. The fuselage has a separate nose section with a pre-installed ballast tube and pushrod guides. It's inserted into the rear portion of the fuselage, and contains the captive nut for the front wing bolt. The fuselage is glass (and possibly Kevlar), with a heavy carbon lamination around the wing chord section, and reinforced longitudinally with carbon. Building Although this a moulded model there is still a fair amount to do (it's taken me 5 months, but then it took me a whole winter of building to put two new control horns on the tailplane of a 60inch racer). The incidence pins are pre-done and the servo wells cut out. However, the fuselage needs to be opened up for the radio gear, the wing seat and centre panel for the connector and the ends of centre and tip panels for the wiring harness.

It's an annoyance to discover that the wing isn't pre-drilled for the control horns and if you plump to top drive the flaps you'll have to take a dremel, and a deep breath, before attacking the top skin, sub-spar and wiper. The Wing As ever, I do the easy bits first. The tip panel roots were drilled for the wiring harness, and Hitec HS-5125 digitals went into the available aluminium mounts (through Soarhigh, though I scrounged mine off Ian Mason). There isn't enough depth to use anything other than a 10mm servo, and even with these one of my flush servo covers bulges slightly at the trail edge. Incidentally, if you use these servos with Multiplex (3030 always, selectable on 4000 and Evo) centers, use 10% centre as neutral to avoid stalling the servo against its internal stops when on full travel. This is because more throw is available when using Multiplex; the pulse length is greater, giving approx 130% throw when compared to JR or Futaba transmitters. Credit for this tip goes to Simon Hall. The servo well is already reinforced with a good weight of carbon, so I just used 5 minute Devcon epoxy to fasten them in. The servos were placed in the middle of the wells for easy access, but measured carefully to ensure symmetry between left and right panels. I'm not convinced the servo wells were identically located in each panel, but the panels do themselves measure up as symmetrical. Tragi adjustable brass control horns are now available through Soarhigh, and were inserted perpendicular to the upper surface through a 4.5mm hole. This hole is drilled 11mm from the hinge line on the top, leaving it 9mm from the wiper on the bottom. This builds in some mechanical differential, and the servo horn can be set vertically. There is plenty of travel with the servo linkage placed on the inner hole of the servo arm. The linkages were made up with 2mm clevis' and soldered to length, once correct. The flat servo well covers were re-used with a slot cut in them for the servo arm; I didn't bother to stick the supplied lexan/polycarbonate bubbles on.

The centre panel root and wing seat were drilled for the wiring harness. Be aware that there really isn't enough depth above the ballast tube for a D-connector or similar. I used a green 6-pin Multiplex plug and socket, set up to lay horizonatally on top of the tube.

After much soul searching I decided to bottom drive the flaps, even though they are top hinged for 90 degree travel. Having to blow the sub-spar, and fashion the insertion of a control horn Brio-style was too off putting. If you want to see how this should be done, check out Andy Ellison's installation on Ian Mason's replacement model; or try and bribe him into doing yours . Tragi horns went in from the top surface again, aiming for 9mm from the hinge line on the bottom. This is 11/12mm from the wiper on the top surface. I dispensed with the locknut to reduce the length of the horn, and reinforced the base of the horn where it protrudes from the bottom side of the control surface. This was in view of the lack of depth in the thin control surface, and the fact that I had to fill and redrill after drilling the holes perpedincular to the bottom surface first time round. Doh!

The shorter horn with the linkage located on the inner hole of servo arm gives me a good 50mm of travel on the flap, with the servo arm canted back about 40 degrees towards the trailing edge when in neutral. Too much mechanical differential, or the control horn too close to the hinge line will leave you with a lot of slop in the control surface. However, there is very little upward movement available or needed in the flap, so don't worry about a linkage installation which constrains upward movement of the control surface.

I used the Hitec HS-5125 digitals, with the aluminium mounts again; measure and installed as per the tip panels. Others have felt the need to install JR DS-368s for robustness. This will need the lugs cutting off and to be glued close to the spar to minimise how far they protrude from the wing surface; you'll have to source the raised X-Model Blade or similar servo covers to finish anything other than a 10mm wing servo installation neatly. The Fuselage The wing seat was drilled for the wing connector. This is a substantial carbon lamination, well and truly blunting some of my Dremel bits. The elevator and rudder servos go in

from the bottom of the model. This requires the appropriate openings to be cut in the moulding; it's designed for the Hitec HS-5125 digital form factor (again!). It may be possible to install other servos with some surgery; it would certainly require the installation of a lowered (or raised, depending which way up you look at the model) servo tray to align the pushrods, and stand a chance of clearing the snug fitting nose cone.

I cut the carbon pushrods for the tail linkage down, and installed 10cm length of threaded rod. This allows the servo to move through it's arc without the pushrod binding in its lengthy guide. I used slim balljoints from Kavan to terminate the linkages, but the nut and bolt length needs to be minimised and the horn sanded slightly to clear the entry lip on the nosecone. In the end I still had to cut some shapely nostrils in the nosecone to avoid the linkages rubbing on the inside. With the nosecone clearance I have, the elevator/rudder servos have to rotated forwards or backwards to get the lip of the nosecone over them. The required rotation is substantial, and just setting the arms slightly forward or back at neutral elevator/rudder isn't sufficient. I suspect Baudis intended a Z-bend to be installed, but this makes removal of the inner nose from the main fuselage impossible, once installed. The V-tail has its torque arms pre-installed, but balljoints need to be soldered on. Despite several irons, solders, fluxes and techniques, we couldn't get the solder to take on the torque arms. This seems to be a common problem, which I solved with 30 minute epoxy. The USA guys suggested Black CA, which maybe the same as Zap-Flex. I was going to try, but my bottle arrived by mail order already dried out. The carbon pushrods were trimmed to length, studding inserted and slim Kavan balljoints screwed on. The balljoints had to be sanded down, and the torque arms adjust with the pliers to get the mechanism to clear each other, the fuselage sides, the tailplane linkage shroud and the rear tailplane bolt. It all seemed exceptionally tight at the time, but didn't actually prove the headache I expected.

The inner fuselage was opened up to fit a 4-cell AA-sized receiver pack, switch and Multiplex Micro-9 IPD receiver. It just fits, and a 5-cell pack might not be possible in the full carbon/balsa model given the quantity of nose weight required. The nose weight spilled over into the battery and receiver compartment in the end; I didn't bother to mould the nose weight as it still wouldn't all have fitted ahead of the receiver pack, and I don't have suitable facilities in any case .

I've seen some installations with the receiver in the top of the fuselage, above and behind the tail servos but ahead of the leading edge of the wing. This looks very tight, and might only be possible with the Hitec Superslim receivers they are using. It also weakens the inner nose at the point it is subject to load in the event of a heavy arrival. In view of the quantity of carbon in the model, I routed the aerial through to the wing seat area out of the bottom (slightly to one side, as there is no tow hook to keep the aerial clear of terra-firma on landing), along and left the last 9 inches dangling. This now appears to a common recommendation for installations with the the Multiplex IPD receiver.

That was the build completed ­ a mere 5 months after delivery! Setup I still hadn't managed to install a CofG at this point, but recommendations points to 4045% of the 240mm chord as a starting point (there is a lot of tail area). The ballast tube is centered around 109mm, and the suing-culture crazy USA recommend a flick-free starting point of 102/103mm. I settled on 105, mainly because I'd run out of lead and it was too late to go to church . The control throws were set as follows, with the measurements at the tip for aileron and tail and wing root for the flaps · · · · · · · · · Flying Planned maiden flight is off of Devil's Dyke in a 12mm NNW. Racing BMFA League, South Wales 1st August 2004 Conclusions Positives · Brilliant value for money o £565 including P&P for the full carbon/balsa? o £200 cheaper than a Samba Brio Extreme? · Availability Elevator - 5mm up, 7mm down o 25% exponential Rudder - 8mm up, 10mm down Aileron - 10mm up, 4mm down o 60% differential in Multiplex terminology o 25% exponential Flap as aileron - 4mm up, 1mm down Flap as snap ­ 8mm down o Applied across full trailing edge Flap as flap ­ 5mm o Applied across full trailing edge o No elevator compensation Flap as spoiler ­ 50mm down Aileron as spoiler ­ 10mm up o Differential suppressed at full up Elevator as spoiler - 5mm down

·

o No 6 month waiting list? o Spares? Strength o Full carbon/balsa is virtually ding proof o Nothing has broken yet

Negatives · Lack of control horn pre-installation o Especially if you wanted to top drive the flaps · Nosecone diameter o Given the lack of clearance for the tail servo linkages · Nose length o Given balance weight required and room available for radio installation

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