Here is a list of all the postings trevor wood 2 has made in our forums. Click on a thread name to jump to the thread.
|Thread: Anyone for a Tiffie?|
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.
|Thread: Bryant Percival Gull 6 E conversion|
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!
|Thread: Dambusters Raid|
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'
|Thread: Anyone for a Tiffie?|
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!
Since collecting the model, t's been residing in the corner of the workshop whilst I finished a couple of HK laser cut kits. With the bench clear of clutter I decided to have a closer inspection of the airframe so I could decide what still needed completing and to plan a work schedule for later in the year. Well, you know what it's like; one thing leads to another, and before you could say "quick set epoxy" I was in to the build process.
The first thing that caught my eye was the tailplane. In BEB's earlier posts he described in some detail the care he took to ensure the incidence was correct, and the surface was correctly aligned. However, a quick eyeball check suggested the RH tip was 7 or 8mm higher and further forward than the LH tip. Hoping this was an optical illusion, I got hold of a tape measure, spirit level, string and set square to double check. No matter which way I measured the alignment, the results were the same - it wasn't mounted squarely. So realising it wasn't going to fix itself, I got hold of the razor saw, put a new blade in the scalpel and took a deep breath.
About 20 minutes later I had completed a successful fin and tailplanectomy.
I was able to take further advantage of this situation and instal the snakes that BEB only realised he had overlooked as he applied the last pieces of fuselage sheeting. He signed off his post with the famous words " it'll be alright. Trust me, I'm an engineer". Well I'm an engineer too, and trust me when I say that installing them was a real struggle. Cutting the holes in the fuselage sides was easily achieved using a section of old aerial as a boring tool. However I wanted to ensure the snakes were adequately supported along their length to prevent buckling when compressive loads were applied. Access to former immediately forward of the tailplane cut-out was through an aperture about 3/4" wide by 1 1/2" long. An hour and multiple failed attempts later, I had a snake support bridging the former.
The next former was more easily accessed through the wing cut out, but it was still located about 8 " aft of the trailing edge and so took another half hour to attach the support. However with that completed I was satisfied that there would be no unintended control slop.
Apologies for the inverted photos. It just seems to be an occupational hazard of using an iPad on some sites. Any IT advice to rectify the problem is appreciated.
Next time, re-attaching the fin/tailplane and finishing the fuselage sheeting.
I stumbled on this thread a couple of weeks ago whilst looking for BEB's Wot4XL rebuild info. It made great bed time reading, particularly the historical instalments. I was saddened when I reached the last page to learn that BEB hadn't managed finish and fly the model, and that it was now for sale.
Out of curiosity, I looked at the eBay listing and saw that bids had only just reached £90. A quick check of the TN Design web page showed the price of the plans, wood packs and mouldings was £191. With the retracts, oleos, wheels and sevos the total was probably closer to £300, so it was fair to assume that a final auction price would be in the region of £150, particularly when the models provenance was taken into account. A quick glance into my hangar ( the upstairs box room) showed there was no more space for something the size of a Typhhoon, but caught up in all the excitement, I made a silly maximum bid of £100, expecting to be sniped during the last minute..
Long story short, the snipers must have run out of ammunition and I ended up with the winning bid. I collected the model at the weekend, and was surprised to learn that it was being sold by a non-modeller who had obtained it at another auction as part of a job lot.
A quick examination showed the Typhoon condition was very much as it appeared in BEB's photograph of New Year's Eve 2013. The plan now is to carry on with the build, although initial progress will be intermittent until the 2019 building season starts in earnest later in the year.
|Thread: Modelflying.co.uk Christmas Advent Competition updates!|
Speaking as someone who never wins any competition, I'd just like to thank the RCME team for making me a Ruler - power at last! Season's greetings.
|Thread: Same motor with different kv|
Except for those occasions when you need fit a large prop to a scale model, or have built a large 2channel retro design for floating around the sky on warm summer evenings, or you want to fit a 4S lipo in place of a 3S in order to reduce the current draw. There will probably be other responses giving more reasons.
Bob beat me to it!
Edited By trevor wood 2 on 07/12/2018 10:01:22
|Thread: Any Electric Only Groups or Clubs in the North West|
BATS at Bramhall in Cheshire is silent flight and electric fixed wing only.
|Thread: WANTED INFORMATION – Balsacraft Hurricane Build Instructions|
Victor, sorry but that's the one piece of documentation I didn't keep.
I modified the wing centre section of my Hurricane and managed to squeeze in flaps and retracts, but the finished weight crept up to 55 oz. I wouldn't recommend doing this to your kit unless you can keep the final weight to no more than 3lbs as the wing loading starts to get a bit too much. One mod that is worth doing is a battery hatch in the top decking in front of the canopy. You will have to reposition some of the formers but it's not overly difficult.
I've placed a set in my photo albums. They are for the electric powered version. If you need the IC powered conversion instructions let me know.
You shouldn't have too much difficulty deciphering them.
|Thread: Design & Build FW 200 Condor / Syndicato|
Full size and model aircraft usually have acceptable handling characteristics over a range of CG positions that is likely to cover 5% of the chord. If your calculated position is correct this time and you have found the CG sweet spot, then everything should be OK. But to minimise the possibility of another 'upset' why not move the CG to what should be the forward limit for your second attempt (perhaps another 2.5% C forward), and then fine tune its position based on actual flight testing. The worst that could happen if you use up all the of the elevator up trim is that you would need to hold a bit of up elevator on the stick.
As someone said earlier in the thread, too far forward - flies badly. Too far aft - flies once.
Robert, l agree with the recent posts that that the likely cause was a CG that was too far aft. In your early posts you describe the model having a 72" wing span, and from the inverted plan view photograph in your back garden, I estimate the wing root chord to be about 10.5". In a later post I recollect that your calculations showed the CG should be at 124mm aft of the LE.
If you ignore the slight sweep back of the outer wing panels and assume a "safe" first flight CG to be at or about 25% MAC, yours should have been at about 66mm aft of the wing LE. If you want to include the affects of the slight outer panel sweep back (or are feeling particularly brave) then you might consider going to 75mm aft of LE for the next "first flight". A CG position at 124 mm would be in excess of 40% MAC, which easily accounts for the vicious pitch up you encountered.
PS. I wouldn't even consider trying to persuade someone to hand launch a 7lb, 6ft span, low wing, 4 engined scale model for a first flight.
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