By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by CML

Anyone for a Tiffie?

Building TN's Typhoon

All Topics | Latest Posts

Search for:  in Thread Title in  

Chris Bott - Moderator18/05/2019 00:00:13
avatar
Moderator
6628 forum posts
1374 photos
1 articles

Trevor I'm glad to see this progressing. Keep up the good work.

The only IT advice I can suggest is to try taking a photo with the iPad held the other way up to usual. Yes I know it rotates on the iPad screen but I've always wanted to know if doing so would help on here.

Chris.

trevor wood 218/05/2019 00:59:09
avatar
37 forum posts
38 photos

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!

Craig Carr18/05/2019 10:39:30
avatar
662 forum posts
423 photos

Hello Trevor,

I have had that happen to me on occasion when uploading from iPhone or iPad. What I did was got into the iPad, select photos and then edit.

you can then rotate the photo 180 degrees and save. Then load into your rcme album as usual.  It should then appear correct way up

craig

Edited By Craig Carr on 18/05/2019 10:41:16

trevor wood 219/05/2019 00:40:42
avatar
37 forum posts
38 photos

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!

trevor wood 219/05/2019 00:53:55
avatar
37 forum posts
38 photos

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 Carr19/05/2019 07:51:04
avatar
662 forum posts
423 photos

Hi Trevor,

this website gives a technical reason click here

craig

Robin Kearney19/05/2019 09:48:03
avatar
1071 forum posts
183 photos

I was going to reply with an explanation but that link from Craig nicely covers it. In short its because the camera/phone hasn't really rotated it, they simply put a little bit of invisible data inside the photo saying 'rotate 90CW' (or whatever is appropriate). And the software that displays it then does it for you when you load the photo.

It seems that whatever software they are using to make the thumbnails etc for this site doesn't honour this extra data so it just blindly assumes the image is the correct orientation - result is upside down images sad

As you've seen, opening it on a computer/ipad in any photo editing software and rotating it twice then saving will actually rotate the image rather than using the Orientation field in the EXIF. They do this because its more widely compatible (as you have also seen) and they typically run on things that are far more powerful than a phone or a digital camera.

The EXIF rotation was added mostly because as images from camera/phones got bigger the the computational job of rotating them became harder for the device, whereas simply writing some text to say which way to rotate it and by how much is trivial.

trevor wood 210/06/2019 23:18:28
avatar
37 forum posts
38 photos

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.

image.jpegimage.jpeg

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.

image.jpeg

To finish off the tailplane structure, a couple of balsa fillets were attached to the inboard end of the elevator aperture.

Chris Bott - Moderator11/06/2019 09:42:57
avatar
Moderator
6628 forum posts
1374 photos
1 articles

That's looking very nice Trevor. I'm following with great interest.

Doc Marten11/06/2019 10:18:17
324 forum posts
2 photos

Me too, the Tiffie is on my build bucket list, maybe this one or the Brian Taylor offering.

Just proves the old mantra that even a small saving in tail weight is a major benefit.

Bob Cotsford11/06/2019 10:41:16
avatar
7835 forum posts
433 photos

11g, as you say, that's worth 2oz of lead in the nose. I'm surprised by the previous structure, I wonder why three layers of sheet? I have the plans squirreled away somewhere from when they were published, but I don't think I kept the build articles.

Bob Cotsford11/06/2019 10:41:19
avatar
7835 forum posts
433 photos

11g, as you say, that's worth 2oz of lead in the nose. I'm surprised by the previous structure, I wonder why three layers of sheet? I have the plans squirreled away somewhere from when they were published, but I don't think I kept the build articles.

trevor wood 216/06/2019 22:47:21
avatar
37 forum posts
38 photos

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.

image.jpeg

Trevor Crook17/06/2019 07:02:33
808 forum posts
63 photos

You certainly have to watch the weight at the rear. My 90% version flies on a 4s 3000 mounted vertically behind the motor, and a 4-cell NiMh to power the retracts also sits under the cowl. Nonetheless it still needed lead to get the cg forward enough.

Now mine is fitted with a lower kV motor (about 500kV) and turns a prop from a Dynam Hurricane. The old 2-blade setup pulled 600W, this one is just over 700 so it flies with more authority. Obviously the proper sized one will need a 6s setup. I reckon the motor/prop combo from the Avios Mk V Spitfire would work well, I've got one and it's rather overpowered for scale. Haven't measured the power, but I reckon it's at least a kW.

Dale Bradly17/06/2019 07:39:16
2 forum posts

Excellent to see another Typhoon on the build. I built this one a few years back and love it. If you want to read about my dramas with weight, (and maybe learn from my mistakes) check out my partial thread:

**LINK**

I'll be following along the read of yours

trevor wood 217/06/2019 11:50:15
avatar
37 forum posts
38 photos

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.

Bob Cotsford17/06/2019 14:31:32
avatar
7835 forum posts
433 photos

I'd expect that a 16*8*3 prop on a 500kv 1300W motor might get a touch hot. E-calc reckons on over 1390W/80A on 5s or only 800W/58A on 4S. I've found e-calc to give a good approximation of what to expect and it shows a 16*8*2 APC-e as giving around 1070W/62A, and as HK show a max current of 60A for this motor even the two blade prop is on the limit. If you want three blades then a 15*7 looks to be about the limit and is estimated as giving a maximum speed of 58mph.

If you went up to a 5055 430kv, then you would benefit from a little extra weight in the nose and it would cope with a Master 16*10*3 at 1260W/73A for 65mph.  Didn't TN fly his on 800W?  A comfortable excesslaugh but that's what you get with a 16" prop.

Edited By Bob Cotsford on 17/06/2019 14:38:52

trevor wood 217/06/2019 15:25:44
avatar
37 forum posts
38 photos

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 Crook17/06/2019 22:29:24
808 forum posts
63 photos

Trevor, the motor in the 6s Spitfire I mentioned is 380kV, and turns a 15x10 3-blader. I think 500kV is a bit high for 5+ cells. The motor is available as a spare from HK, as are the props. The latter come as a blade set and a very strong hub/spnner set, each costing about £6.50.

It's ages since I looked at the plan, but I thought it showed the battery in a vertical box that's on the front of the firewall, with the motor on the front of the box. That's how mine is, with a hatch underneath via the cowl. This gets the battery as far forward as possible. I'll try to post some pics in the next day or so, meanwhile if you look at the shot below, and imagine the lipo in front of the line that seperates the cowl.

dscn1041.jpg

trevor wood 217/06/2019 23:15:21
avatar
37 forum posts
38 photos

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.

image.jpeg

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.

image.jpeg

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.

image.jpeg

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!

Find RCM&E! 

Latest Forum Posts
Support Our Partners
Revoc
Motion RC
CML
Wings & Wheels 2019
Slec
electricwingman 2017
Gliders Distribution
Pepe Aircraft
Advertise With Us
Sarik
Latest "For Sale" Ads
Does your club have a safety officer?
Q: Does your club have a safety officer, or is the emphasis on individual members to each be their own safety officer?

 Yes we have a SO
 No, it's down to everyone

Latest Reviews
Digital Back Issues

RCM&E Digital Back Issues

Contact us

Contact us