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Infinity 90 Build

How good is it ?

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cymaz10/04/2019 06:06:26
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8586 forum posts
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Thanks for the feedback yes

  • I’m sure I’ve got Clearcoat somewhere
  • The down thrust needed is very minimal. It’s a major job to get back under the engine mounting. I will try the mix first, if that proves problematic then it’s out with the tools
  • I’ve found the rates a little to “lively”, it seems half rates suit my speed of flying

cymaz13/04/2019 13:36:14
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8586 forum posts
1161 photos

Taking good advise from earlier postings I will add a bit of down thrust.

Mrs C is at work on Sunday, the weather is sunny combined with a howling gale...so no flying. I can settle down quietly on my own and get it done, after the housework though.

cymaz14/04/2019 11:54:00
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After 2 hours of work, ( it’s a long boring story) finally got 0.9* of extra down thrust. Just have to fly it now....if the trees stop bending sideways in the howling gale.

Edited By cymaz on 14/04/2019 11:54:52

cymaz16/04/2019 19:20:33
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8586 forum posts
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Test flew it after work today. The extra down thrust had made a world of difference. Much less pitch sensitive. Aileron rates cut down and a tad more expo added. More rudder throw as well.

Edited By cymaz on 16/04/2019 19:21:31

Bruce Collinson16/04/2019 19:35:55
384 forum posts

Good.

Remind me, what’s the absolute downthrust angle do you think?

Hoping to get mine up at the weekend...as it were.

BTC

cymaz16/04/2019 20:53:10
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8586 forum posts
1161 photos

Quickly done a couple of photos. If I had time I’d have put the wing on and got the correct starting incidence from there. So, here is the tail set at 0*

86836011-1e81-47df-9140-ece1029a0432.jpeg

And here is the angle showing on the back of the spinner at 0* at the tail. The photo is 90 degrees out

Hope this has helped somewhat. Sorry it was a bit rushed. I guess that’s 2.4* down thrust 

 

3f0ccc3d-e619-4106-a0d3-0714b92664c1.jpeg

Edited By cymaz on 16/04/2019 20:54:21

Edited By cymaz on 16/04/2019 20:55:00

Peter Jenkins16/04/2019 23:53:13
1234 forum posts
132 photos

Cymaz, you would get a more accurate reading of incidence if you use a bar with clamps that centre the TE and LE as in the photo below. This is a Robart incidence meter and it is also available as a digital readout meter.

Gangster 37.jpg

In this case, it is a Gangster 75, the aircraft was specified as 0 deg for tailplane, wing and engine down thrust. Side thrust was 2 deg but I've since increased it to 2.5 and it looks like it will need almost 3 deg to go straight up.

Bruce, there is no absolute downthrust setting. You just keep adding down thrust until when the aircraft is trimmed for half throttle, or possibly a bit more, you do not get any pitch up or down when you smoothly apply full power. That is until the aircraft has accelerated sufficiently to increase the lift being generated by the wing when it will start a gentle climb. Equally, when closing the throttle, you don't want the aircraft to pitch up or down as the throttle is closed.

On my Agenda, which has an electric contra drive, the setup is -1 for the motor, +1.5 for the wing and zero for the tailplane which happens to be an all flying tailplane. There is no side thrust in this instance as the contra prop removes the need for any.

Hope that helps.

Edited By Peter Jenkins on 16/04/2019 23:53:59

cymaz17/04/2019 05:28:24
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Peter

Thats what I would of done as I mentioned in my post. In my defence, it was late, busy day at work as well, and I was ready to hit the sack.

Peter Jenkins17/04/2019 11:20:49
1234 forum posts
132 photos

Cymaz, sorry, I clearly didn't read your words closely enough. You can still use the bar for the tailplane incidence but you do need the elevator servo powered up to avoid the elevator dropping with the weight of the bar and sensor. As you say, time was short but thought it worth mentioning as others may not realise that just using a sensor with a very short measuring length will lead to significant inaccuracies.

Bruce Collinson19/04/2019 19:34:31
384 forum posts

Well I managed to get it up not once but three times, after a lengthy intermission involving a Laser 100 and a bottle of fuel which had evidently passed its sell-by date. Fortunately I had a fresh bottle, on which it fired, ran and idled.

needed some trim but luckily the Yeti had just been fitted with aftermarket joysticks so they can be used intuitively and by feel. Not overpowered by any means but nice to fly albeit loads of down in inverted so I suspect the c of g is a bit conservative.

Loads of trim loose so have just ordered Prymol, a scarce resource. Anyone know the generic substitute? Etch primer for plastic film?

BTC

cymaz19/04/2019 20:42:07
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8586 forum posts
1161 photos

I’ve done the edges with Clearcoat.....so far so good

cymaz12/05/2019 17:28:30
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8586 forum posts
1161 photos

Had 7/8 flights all day with it. Handles the cross wind landings and takeoffs well. Bruce, Added more down thrust. Tracking better. Adjusted and fine tuned mixtures, elevator expo, throttle throw on the servo end.

Really liking this plane more and more. Now got 17x6 apc pattern prop.

cymaz12/05/2019 17:28:32
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8586 forum posts
1161 photos

Double post 

Edited By cymaz on 12/05/2019 17:29:13

Bruce Collinson13/05/2019 08:47:57
384 forum posts

Interesting, good progress. Thanks for the update.

Mine is "stalled" pending A Certificate attempt in a fortnight, new oval tank fitted, c of g still to do. Flies really nicely but underpowered, toying with a Laser 120 after I've tinkered with props. Have a 155 but strongly suspect it won't fit.

Happy landings!

BTC

cymaz13/05/2019 17:13:15
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8586 forum posts
1161 photos

The DLE 20ra installation is a REAL pia . However once set up it a oodles of grunt and the 17x6 APC provides enough thrust but grips the air well for landing . Yesterday there was a 90’ cross wind. I let it crab in with no wing rock at all under a tiny bit of power and at the very last minute put a good amount of rudder on to straighten things up and it’s a winner.

Bruce Collinson13/05/2019 18:26:19
384 forum posts

For Pakistan International Airlines, am I reading “pig” correctly? Unnecessarily tight, isnt it?

been meaning to ask, have you settled on a c of g which is reliable? Measured from the root le would be very welcome. I’m halfway through making space for Veronica to do the Infinity and my big Yak.

BTC

cymaz13/05/2019 20:06:03
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8586 forum posts
1161 photos

I’ve got a temperamental rcgf 30cc to beat into submission. If you can give me 24/48 hrs I will gladly measure it.

Bruce Collinson14/05/2019 09:42:28
384 forum posts

Yes, saw that. Petrol 2 strokes; little girls; when good, v. v. good, when bad, awful etc. Somebody's 100 twin something ... begins with a D ... doesn't help, does it? ... Sunday, not quite on song, cowl off, much huffing, one head loose. An hour later it was back together.

I will gladly wait, as preliminary foray into the outside mancave last night did not clear enough footprint for the Valerie rig but did disturb a couple of arachnids whose footsteps were clearly audible and which might require the weed gun on full heat to evict; plus I suspect there's either Lord Lucan and Shergar, or a Japanese sniper, under the bench. And the weather is very flyable!

Do it when you can, I'll be grateful.

BTC

cymaz19/05/2019 10:41:50
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8586 forum posts
1161 photos

Bruce, I will measure the CG but not had a good day Saturday angry. Ignition battery decided to drop a cell just at the point of no return, it was flyin’ flippin’ great as well.

 

Despite all all the trails and tribulations the more I fly it the more I think ...

what a super airframe

Ive emailed DS models in the Far East ( who now seem to make it), to see if they can send me a new horizontal stabiliser and elevators. I will phone Probuild on Monday. Hopefully someone comes up with the goods before I try and glue the thing in straight. That is the only damage, nothing else.

79f80c28-cdb7-4ab8-8175-e2485514c413.jpeg

 

7fda0fac-e422-4120-9d85-3c569a42d495.jpeg

Edited By cymaz on 19/05/2019 10:42:42

cymaz19/05/2019 10:55:39
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8586 forum posts
1161 photos

Bruce, having lightly taped the elevators in place, the CG I’m using is 140mm. 17x6 APC suits the DLE20ra.....goes up and up.

....Or it did blush

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