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4th 2021 2m F3-RES, F5-RES 14 day Duration Challenge


martynk
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cirrusRC

Got out for a few hours today.   Grass at the field is very long,  not ideal for bungee launching.     Grey sky, no sun but warm.  Hardly any wind - my indicator was spinning round like a broken compass.   Lift firing off all over the place.     No kites but conditions looked great.

First couple of launches I could see why the kites were snoozing.     Air was like treacle.    Light lift and very narrow.    It felt like the whole sky was full of feeler tentacles hanging off the main thermals higher up.     It meant lots of false positives.   One minute you were in good lift, the next minute it was gone.

First 2 launches were around 7 minutes.   3rd launch, worked some light lift before finding something stronger.    Took me up to 500 meters,  hovered around this height for a few minutes before the lift turned super light.   No major sink but gradually came down, eking out the time by working patches of light lift.      Was hopeful at the end but it never developed.    Landed with 42:20 on the clock, shortly before the rain arrived.

Suspect the field will be closed soon so might be a while before I get to give this challenge another go.    Right on Q for the June heatwave!

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StraightEdge

Another excellent time David, another fascinating narrative.

You're welcome to pop over here any time the weather is right; grass is lush but the field remains open.

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cirrusRC

Thanks Jon, appreciate the offer.  Let's see how the weather works out.

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I did 27 flights on Thursday - I had forgotten how exciting the 15:23 was until I downloaded it today.  Got below 11m at one point.

 

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martynk

Just got back from a week away so I'll update the tables later. 

 

Mike, have you set your altitude cut off to 50m?

 

 

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No it was set to 175m and I guessed when to shut down!  I didn’t have access to the means to reset on Thursday - I have 60m/20sec set now.

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StraightEdge

Current state of the grass.  Ideal for trimming FF scale models but not so sure about the bungee... I should train him to sniff out and retrieve the pennant!!

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Whitmore

Those ears 😂

10 hours ago, StraightEdge said:

Current state of the grass.  Ideal for trimming FF scale models...

Yup! Although I now have mad itchy knees and streaming hayfever from tramping about in shorts all morning.

 

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Graham Lorimer

Another lovely day at Fish Meadow, and lots of 2 meter flights with Purito and Circle Dancer.

Purito came out on top today with a best of 36 minutes 40 seconds. It was the very first flight of the day, and despite numerous attempts, nothing better was achieved. Nearly 10 minutes of scratching around looking for something to ride up on, and persistence paid off, despite dropping down to 40 meters twice. Finally got everything working, and made 500 meters for a short while, and whilst dropping down at 25 minutes, got another ride up to near 400 meters.

Interesting piece of information for anyone wondering about battery use, using a fully charged Hacker 350 mahr battery, it only took 115 milliamps to top it right back up after the launch and 36 minutes of flying.

Circle Dancer had a best of 15 minutes 40 seconds.

Graham Lorimer

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cirrusRC

Amazing how many flights we have around 36 minutes.  One of these days we will hook up 4-5 separate big thermals including descent and climb.

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Graham Lorimer

The problem is you really do have to jump from Thermal to Thermal, otherwise you end up too high or too far down wind and these little models do not float for long in average or bad air, and even at 400 meters, you really don't have long to find the next thermal.

GL

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StraightEdge

Nice one Graham, and thanks for the useful data on battery usage.

Interpolating from my own earlier bench tests, I'd very roughly guess that each 20s launch will account for about 60mAh, the other half of your 115mAh used being the relatively extremely modest demands of rudder and elevator over the half hour.  Just so long that the real boomer doesn't come along after several prior unsuccessful launches on the same Lipo...!

My repaired and electrified X-RES is ready to test fly this afternoon.  It now weighs 520g (was 450g as a pure glider) with a 3s 450mAh battery.  I'll have the PuRES and the bungee with me as well, so will be interesting to see how they compare in the same conditions.

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martynk

I maidened my F5 version of Mad Hatter this morning. The first attempt yesterday was a disaster. The model was a little under elevated and the boom snapped in front of the tailplane where the snake protrudes on a hand launch test glide. So yesterday, back into the workshop, add an internal cf sleeve brace and retry this morning.

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 Only 3 flights on the 250mA 2S battery. The first, despite a launch directly into the sun, was the best but only 2:59 from a pretty lousy low transition. The next two were in dreadful sink but I was calibrating the glide and testing the spoilers so wasn't too concerned  I then managed to break a wire to the LiPo connector when changing a battery so that was the end of flying today.  A bit too breezy for record breaking scores anyway. 

However, it flies and seems to be very gentle in pitch and yaw authority is good.  Not brilliant, but, at least its a score.. 

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StraightEdge

Maidened the repaired and electrified X-RES this afternoon.  Not posting a time as (i) haven't yet fitted the Altis, and (ii) it was just too windy to even bother trying to exceed a couple of minutes or so... even the birds seemed to be sitting it out!

This, my first ever electric-launch thermal model, was really quite unstable in pitch until I increased expo and added a 5g weight behind the bulkhead (aft of the motor), which tamed it but not quite as much as I'd ideally like.  The other problem (although hard to unpick because of the strong wind) seemed to be a bit of viscous tip-stalling if turning too slowly or too tight.  It certainly doesn't feel as 'nice' as my much lighter bungee-launched PuRES, but reserving judgement until I can fly it again in more suitable, calmer conditions.

Launches on full power at a 45-60° angle (higher angle due to strong ambient wind) to 60m in about 10secs, and 100m in about 15secs, the latter using about 40mAh (very roughly).

So proved concept (to myself at least!) at a modest cost by repairing and fitting a power-train to this previously damaged model (which was never that great when I bought it second hand and had to bully a load of warps out the wing!). I'm sure I'll get more used to it this season as I tweak things and learn about its quirks... and there'll be time to build a pukka new one (choices, choices!?) next winter.

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Brian Taylor

 A lovely day yesterday, 22deg with a variable light SE  breeze ranging from flat calm to 4mph. The flying field grass is suffering the same fate as others -  getting rather long now but luckily there are a couple of light aircraft that fly from here, the farmers Tiger Moth and a Piper Cub used for aerial photography and banner towing, so there is a nice mown 25m wide strip right down the middle. All I need to do is train the bungee to fall back on that instead of hiding in the long grass!

The first 6 flights all managed between 6 and 12 minutes with plenty of small thermals kicking off but none of them producing anything spectacular. On the seventh flight the glider seemed to hit a brick wall on the tow at around 15m and then recover, shown as the "step" on the plot ( maybe the line snagged and released but I didn't see it do that) A string of small thermals came through though they never produce long lasting lift with 204m being the max altitude recorded. Any way it was very pleasurable flying being able to leave one thermal and  move back up wind and pick up the next without too much effort.

The  -SF plot  is my flight timer switch on /off , anyone know why Opentx Companion Log Viewer gives such awkward time scales? I was using the FrSKy Archer V6 receivers internal altimeter which for some reason hasn't read zero on landing. I have an altimeter reset function to zero it before launch - guess they aren't that accurate.

5 Jun 21

Slite V2 RES

21min 44 Secs

Cheers,

Brian

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cirrusRC

Nice flight Brian.  The altimeters have a habit of drifting.  It can be improved by letting them stabilise on the ground for 5-10 minutes before launching and resetting.   They are useful as a guide but not super accurate.

Was hoping to meet Jon for a fly today.  Wind looks perfect but risk of rain most of the afternoon put us off.  Legs will thank me after cycling 100 miles yesterday.  Gives me a chance to work on electrifying dad's old Dunne Tailless model.

Martyn, can you add my time to the table please 😀

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Brian Taylor

Not familiar with the Dunne Tailess model but it sounds an interesting project. Think I might look at  the Purito E F5 RES as a winter building project. I’m quite at home with the bungee but there are times when the grass / ground conditions mean the option of electric launch would be handy and also quicker if popping out for a quick hour or so.

Cheers,

Brian

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StraightEdge

Well it didn't actually rain (I've rarely known a day with such a constantly changing forecast hour by hour!) and it remained relatively calm, quite warm and humid, with lots of cumulus but little direct heat to generate proper thermals - so my lastminute.foray to the field at teatime yielded nothing better than 4:25 with the PuRES off the bungee... the best in a repeated game of launching to 60m or so then staving off descent for as long as possible each time.

Jon

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martynk
On 06/06/2021 at 10:46, cirrusRC said:

 

Martyn, can you add my time to the table please 😀

Apologies for that, I occasionally need a nudge and I don't take it personally. :D

Updated table.  Any more errors or omissions?

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Thanks all ..

      

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