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Tim's Skywriter Build

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Tim Ballinger16/05/2017 08:33:20
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540 forum posts
227 photos

Good idea about the expo, a function I have not used yet .

Looking at the weather forecast ; flight is not going to happen any time soon. Just rain and wind forecast for the next week. Still we needed the rain.

Tim

Lindsay Todd16/05/2017 10:32:23
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1694 forum posts
1699 photos

All original movement correct I always use about 25-30% expo so that's a good idea, beautiful scheme and build good luck with the maiden. Linds

Tim Ballinger16/05/2017 11:14:05
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540 forum posts
227 photos

Linds, Many thanks. Good to have the designers view.

Tim

Tim Ballinger19/05/2017 10:19:25
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540 forum posts
227 photos

Pilots notes.

First Flight and landing......

Still all in one piece smiley

However the cg was too far back and it was an interesting ( == scary) ride for the first couple of minutes. Dual rate gave me a set of reduced control throws which helped . Moral here; stick with Linds plan position of 70mm from LE and ignore the clever formulae !

Power as expected was way over the top coupled with forward cg gave an almost vertical climb out but throttled back she flew really nicely.

Been having an intermittent issue with the radio whereby the tx switches either stay on or come at will. Guess what in the middle of the maiden flight the throttle lock came on. Got rid of it but this was also a bit scary !

Being holding off sending it back until it stays in a 'failed' state as intermittent faults are a real pain to sort. I think its going back anyway now as I can do without that .

Landing was smooth and uneventful once I had calmed the nerves !

Would like to change the cg and go back out while the weather is good but it will no doubt take some time to get the the radio back and I can not risk that happening again.

Ace model though !

Lucas Hofman19/05/2017 10:54:16
596 forum posts
316 photos

Good to hear all ended well! And thanks for the heads up about the CG.

Lucas

Tim Ballinger19/05/2017 17:56:40
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540 forum posts
227 photos

Thought a pic in the air was worth a post.

skywriter.jpg

Tim Ballinger28/05/2017 12:01:55
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540 forum posts
227 photos

No flying yet as waiting for radio to come back. Hopefully this week so I cut the field in anticipation. Was nearly long enough for silage!

img_0053.jpg

Tim Ballinger31/05/2017 16:59:16
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540 forum posts
227 photos

Well pretty pleased with the 4 flights today. The new cg position has cured the bucking bronco i had on the first flight.

She flys really nicely and is very responsive, may even cut the aileron throw down a little but I'll wait its quite nice to have something with a bit of zing. Hardly been above half throttle yet so plenty in reserve. Got as far as 1 loop and 1 roll.

We came back in one piece again albeit I had a mixture of landings ! One was just too short and I clipped the long grass which tipped me over but all was well. Next was a little too fast and fairly firm as I did not want to run off into the long grass the other end. Not sure if this site takes videos so I loaded a clip on to utube .... **LINK** warts and everything. One landing was a perfect three pointer right on the spot but my other half did not have the phone recording for that one. ( You'll have to take my word for it)

Really pleased with the way she looks in the air. Need some practice now.

Tim

Lucas Hofman01/06/2017 07:09:02
596 forum posts
316 photos

Hi Tim,

Thanks for the video. The roll rate (assuming that was with full aileron) looks fine to me. But the plane is "hunting" in the up/down direction. Both during take off and approach to landing. That could be due to:

- thumbs on the sticks instead of having the stick between pointing finger and thumbs. Especially then spring tension on the stick is low this leads to jerky movements (ever tried writing with your thumb only?)

- too much elevator movement (if you need it to prevent nose over you can tame it with more expo. 40% is acceptable)

- a CG that is too far back. A plane become less stable when you move the CG backwards. You can always some lead taped on the nose to see it flies better.

Or a combination of the above. Aim for a slightly longer take off run followed by a shallow climb i a straight line to circuit height. Same for landing - long straight approach til flare. If things become unstable abort and go around.

Good take offs and landing are very satisfying.

Tim Ballinger01/06/2017 07:49:50
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540 forum posts
227 photos

Lucas,

Thanks for the thoughts. Nerves responsible for most of it. Subsequent takeoffs were better. That undershoot was caused by that excessive pitch down on finals. That elevator is very powerful so I might dial in some more expo like you suggest. I had all the deflections at a reduced rate compared to the numbers I started with, I think the Aelerons were at 75% of what I posted before and on reflection they feel about right. I'll measure them all again when I get where is comfortable for me. CG feels right now it's just the pilot to sort out !

Tim

Tim Ballinger01/06/2017 19:51:54
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540 forum posts
227 photos

Another session this evenening ,bit more wind which made spotting the landing a lot easier. Really enjoyed this evening , really big lazy loops and me a bit more relaxed. As I was running with a bit of down and right trim which was not needed under no power I Think a a smidge more downthrust and right thrust on the motor is required. A single washer should suffice.

Tim

Tim Ballinger15/06/2017 11:54:43
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540 forum posts
227 photos

Quick update. Had about a dozen sessions now and still in one piece !

I have definitely got it well over powered, it is currently limited to 80% max power and I am probably flying most of the time at half that. Will probably change the motor when I find a project to use the power of the current one.

I have the deflections cut down quite a bit from where I started as it is definitely a very sparky performer if you want it.; at least it seems it to this old pilot.

I think it's at its best flying really slowly when it really does look like a proper old biplane. As I think Linds said originally it is however quite slippery so if you only have a short strip like me, beware.

I guess I could cut the grass more often but as it gets longer I have decelerated into a slow motion nose over on a few occasions now so I might just bend a new u/c with a bit more forward rake.

That's it for a bit , off to the Weston park show tomorrow so hope the weather holds.

Tim

Lucas Hofman15/06/2017 12:41:48
596 forum posts
316 photos

Hi Tim,

You are quickly becoming the expert on Skywriter flying. I am looking forward to getting her completed coming winter.

Start exersizing on side slip to steepen your approach. It is fun to do (if you get the nack) and looks very authentic.

What size wheels do you have. Ballerina's 80 mm. wheels never nose over. It is worth giving bigger wheels a try, a more forward raked gear can lead to instability (and ground looping) on take off.

Cheers, Lucas

Tim Ballinger15/06/2017 13:07:58
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540 forum posts
227 photos

Wheels are same size as yours Lucas. It only happens when grass is too long and it seems to grow inches every night atm. I didn't quite give the full rake first time round so I have a bit in hand. Loved sideslip when I flew full size but never tried it with a model yet. So much easier when you are sitting in it.

Tim

Tim Ballinger15/06/2017 13:09:48
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540 forum posts
227 photos

... and of course with anything over a 5 mph breeze and flying at the right speed the approach is steep enough anyway. Its just those nil wind days when she flys on a bit.

Low pass Pete16/02/2018 13:19:21
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214 forum posts
121 photos

Hi Tim

I am hoping to complete my Skywriter soon but looking at the plan and article published in RCM&E cannot find any ref to control throws. Any advice would be very helpful as you have flown yours.

Best Regards

Peter

Tim Ballinger16/02/2018 13:43:00
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540 forum posts
227 photos

Pete,

Good to hear another one is ready to fly. As it happens I am about to take advantage of today’s sunshine and take mine out for a fly. However I find it very responsive at the plan cg position and my notebook tells me I am currently using:-

Ailerons 7mm (L) 9mm (H)

Elevator 20mm (L) 27mm (H)

Rudder 25 mmm

I also have 40% expo on everything.

Hope that helps

Tim

Tim Ballinger16/02/2018 14:51:47
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540 forum posts
227 photos

Pete, I actually flew on the high rate today as it was a bit gusty and it just gives you that bit faster roll response so that is probably the best place to start. Mind you I am an old slow pilot so you might want it spiced up a bit anyway!

Tim

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