trevor wood 2

Not Raptors, but a feature on "one of the oldest model aeroplane flying clubs in the country"' to be broadcast on Countryfile at 6pm, Sunday 15th December. Apologies if this info has already been posted elsewhere on the forum.

Having spent most of my time so far working on the fuselage, I decided a change was needed so had a look at the wings. BEB had made the sensible decision to group all the wing wiring onto a multi pin socket firmly attached to the centre section. This will simplify wing attachment when preparing the model for flight. I thought it prudent to undertake a continuity test of the wiring as it was more than 5 years since this had been installed. I connected the multi pin plug into the socket and then attached a servo tester and battery to each of the flying leads in turn. The ailerons and landing gear checked out OK, but only the RH bomb release functioned correctly, the LH one just made a buzzing noise as though the servo had stalled. When I loosened the release attachment screws and retested the releases, the buzzing noise was reduced but I saw the RH side move forward as the LH side moved rearwards. At this point the only conclusion I could come up with was that the sevos had been installed as mirror images as you would for twin aileron servos and not in the same orientation as you find with twin flap servos. BEB had posted a photo of the RH side when he was constructing the wing, which showed the servo was intended to be permanently attached with no provision for easy removal. Using this photo plus the TN build plans I was fairly certain where the LH servo was located. After thinking about it for a while and failing to come up with any alternative course of action, I marked the top skin and cut out a rectangle about 2" x 2". Fortunately, the servo position was a mirror image of the RH side so fixing the problem was looking as though it would be easy. I removed the two attachment screws and tried to lift the servo, but it wouldn't budge. It appeared that BEB had used the "screwed and glued" method of attachment (and why not - it was never meant to be removed). Access was limited with little chance of levering it to break the glue joint, so I got out a small razor saw and started to cut off the attachment lugs. After removing the outboard lug I managed to twist the sego sufficiently to separate the LH lug from the bearer. It was then a simple task to turn the servo through 180deg and reattach with a screw on one side and a balsa wedge on the other side that was CA'd to the adjacent inboard rib. Having struggled to get the sevo out, I was confident that this method attachment would be more than strong enough. I then tidied up the edges of the aperture by cutting at a 45deg angle rather than vertically, and made a matching closure panel with 45deg chamfers. This method was described by Danny Fenton in his Chipmunk build articles that appeared in RCM&E a few years ago when he needed to repair the landing gear attachment. It allows the cover to be dropped into place without falling into the void and provides an increased gluing area. A light sanding and one more job was ticked of the list.

Bob, I thought I might be pushing the motor a bit too much, and your calcs show that is more than likely. I was at Weston on Saturday and found some Master Airscrew 15x7 3 blades. By the time I've rounded off the tips they are likely to be 14.5 x 7, so that could be one solution. As you say, TN flew his on 800W, although it was a bit lighter than mine is likely to end up. I'm aiming for no more than 1000W, which should be achievable with the 15x7 perhaps with a bit of end point adjustment on the throttle to limit the power.

Trevor, I'm also thinking of using a 500kv motor (a Propdriive 4258 from HK) with a 3 blade prop. HK's 16 x 8 with the tips rounded off looks to be about right, but only a watt meter will prove whether that's true. I understand your warnings about keeping an eye on the weight, especially at the back end and the electric scales have a reserved parking spot on the work bench for this project. Because the prop is possibly a little larger than the norm for this model, I'm going for a 5s Lipo rather than a 6s. I made some cardboard 'space models' of batteries in the 3,500 to 4,000 mAh range but couldn't get them to fit through the radiator opening. I was reluctant to leave them in the model for charging, so came up with a plan B. Robotbirds had some 2,600mAh/35c lipos on offer which would just fit through the cowl and lie horizontally below the motor. Better still there was space for two of them, so connected in parallel I will have a 5200 set up that should give flight times approaching 8 minutes. Dale, thanks for the link to your build. It's confirmed my thoughts/fears of the importance of weight control. As you've read above, I've already made a start saving every gramme, and like you, intended to make a built up rudder in place of the solid 1/2" sheet one shown on the plans. My servos and Rx will be fitted to a shelf immediately behind F1. I've got space for a 2s Lion battery and UBEC immediately below the motor. I like your method for installing the cannons, and will borrow that for my model. I noted that you said the taxiing was 'interesting' with a fully castoring tail wheel, so I plan to fit a short link rod from the rudder control horn to provide tail wheel steering (yes, an extra 3 or 4 grammes just where you don't want it!). With the airframe mostly complete and most of the electrics now sourced I put everything on the scales, and making an allowance for glassing and painting, I have a target AUW of 8.5lbs, plus whatever amount of lead is needed to get the CG into the acceptable range.

The observant amongst you may have noticed that something had been overlooked in the last photograph; I had (another) senior moment and forgot to install the elevator joiner before completing all the reskinning and fillet work. This was in spite of the clear warnings included in TN's original build instructions that appeared in RCM&E. I was now faced with drilling an accurate hole close and parallel to the hinge line. The space limitations meant I couldn't even use a conventional pin drill to make the hole. After a few moments thought l made my own pin drill by epoxying a short length of discarded aerial tube onto a piece of snake outer. The end of the aerial tube was roughed using a hack saw blade and then pressed into position and the snake rotated between finger and thumb. The flexible snake acts as a universal joint and allows the clearance necessary to rotate the tool by hand. With the hole drilled , a length of 12swg piano wire was bent into a right angle at one end and slipped into place. The next job was something I wasn't looking forward to - trying to bend another right angle on the other end without damaging the balsa. I gripped the wire very tightly in some mole grips, slipped an extension tube over the end of the wire and pulled. I was lucky and ended up with a good bend.

You seem to have all the bases covered; a good motor installation and easily accessible battery will make it easy to prepare for flight when you take it to the field. Also, that motor should be reasonably unstressed at the quoted max power level. It should give the Gull very acceptable performance. I'm sure that Cindy will be very happy!

Interesting radio series by the Australian Broadcasting Company from 65 years ago telling the story of the Dambusters raid, and what 617sqn did next. Much better than listening to Radio 4's 'Book at Bedtime' **LINK**

With the fuselage snakes installed, I was now able to reattach the tailplane using expanding Gorilla glue after carefully sanding one side of the seat to make it level and square. The area around the attachment was covered with masking tape and I used only sufficient glue to minimise any excess needing removal after it had foamed and set. Thanks to Craig and Robin, the iPad photos illustrating the work can now be displayed in the correct orientation. Whilst the tailplane was, subjectively, the right weight for its size, the fin just felt too heavy even though it only weighed 28grammes. I decided to make a replacement in the hope I could save some weight. The original was 12mm thick and made from thre laminations of balsa (4.5mm/3mm/4.5mm). I constructed a central frame from 6mm square balsa which was covered in 3mm sheet. Once sanded to shape the new fin produced a magnificent saving of 11grammes. Whilst this may not seem much, the short forward fuselage of the Typhoon produces a 6 to 1 moment ratio and therefore means that 66 grammes less lead will be needed in the nose to achieve the correct CG. To finish off the tailplane structure, a couple of balsa fillets were attached to the inboard end of the elevator aperture.

I've just been playing with the iPad photo edit feature. If you rotate 180 deg and save, then rotate another 180 deg and save (ie. the photo in the iPad now reverts to being the correct way up), when you upload it to this site it no longer inverts. Success, but why?

Craig, thanks for the info. It all made eminent sense, but guess what....... I uploaded an inverted photo from my iPad album and, infuriatingly, it also appeared inverted in this forum's album!

I've turned the screen upside down with the screen rotation locked and unlocked and taken photographs, but in both configurations the actual photo recorded on the iPad is always displayed correctly orientated. Perhaps Apple should develop their technology and incorporate it into a Rx as a 'panic mode' anti-crash feature!