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Old Apr 20, 2012, 09:21 PM
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Originally Posted by StarHopper44 View Post
Anyone who has followed this thread cannot have missed my trials & tribulations re the published vs recommended vs actual vs practical Flying Weight (AUW), and getting that weight located in the best position -- ie, finding a 'new' CoG if it came to that. I've established (herein) that the specified 'Flying Weight' can NOT be correct for the powered version - it's what the plane weighs without a battery! Perhaps that recommended weight is for the non-powered set-up -- I don't know. But wouldn't you think it a bit odd that, considering how much a motor/prop/LiPo/ESC weighs, that the Specs don't specify a powered and non-powered AUW?

I have seen it with other times ..even more blatant..

I have a SIG Ninja. its a wooded glider with foam core wings (balsa sheeted) wich cames in kit (good old small sticks and bit kits ) ... the box and manual say flying weight 860-950g..

Mine was done acording to the kit exactly.. only difering in extra reinforcement of the tail (that might add 50g slighty after the CG..so lets say 70g overall) and 2 servos for the ailerons instead one.. and no metal torque rods.. mine centered weighted 1210g after having to add 160g lead to center

I also built long ago a Escuela2000 glider (like an elektra) wich manual claims 1100g flying weight.. after completing it exactly by the book it was 1200


Well.. thanks for the adivises... lookin forward for tomorrow maiden (if weather allows )
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Old Apr 21, 2012, 03:03 AM
Heli's and gliders, what else?
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Nederland, GE, Slijk-Ewijk
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Originally Posted by traumkumy View Post
Hi there,

Wanted to share you a good day of sloping yesterday with the phoenix:

http://www.youtube.com/watch?v=RPbnnyw8Jc0
Very nice video, I wish the weather here would improve a bit.......
Again proof that the Phoenix is a great sloper!
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Old Apr 21, 2012, 05:51 AM
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Originally Posted by JLT_GTI View Post
I have seen it with other times ..even more blatant..

I have a SIG Ninja. its a wooded glider with foam core wings (balsa sheeted) wich cames in kit (good old small sticks and bit kits ) ... the box and manual say flying weight 860-950g..

Mine was done acording to the kit exactly.. only difering in extra reinforcement of the tail (that might add 50g slighty after the CG..so lets say 70g overall) and 2 servos for the ailerons instead one.. and no metal torque rods.. mine centered weighted 1210g after having to add 160g lead to center

I also built long ago a Escuela2000 glider (like an elektra) wich manual claims 1100g flying weight.. after completing it exactly by the book it was 1200


Well.. thanks for the adivises... lookin forward for tomorrow maiden (if weather allows )


Why do ya reckon they do that? Is it some vain attempt to make their wing-loading figures look better than they actually are, or something?

This (P2K) is my first 'real' glider of this type, so I don't know that much about the 'science' of the mfr's thinking....ie the things they want to impress everyone with, or why. Do they think we don't have scales, or that we won't actually weigh the darn thing??

It's all a huge mystery to me, why they do these things such as claiming numbers that are just absolutely wrong. What's even more amazing is, how pervasive this practice is in this industry.
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Old Apr 21, 2012, 09:31 AM
Row 0, Seat A
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Originally Posted by StarHopper44 View Post
Why do ya reckon they do that? Is it some vain attempt to make their wing-loading figures look better than they actually are, or something?

This (P2K) is my first 'real' glider of this type, so I don't know that much about the 'science' of the mfr's thinking....ie the things they want to impress everyone with, or why. Do they think we don't have scales, or that we won't actually weigh the darn thing??

It's all a huge mystery to me, why they do these things such as claiming numbers that are just absolutely wrong. What's even more amazing is, how pervasive this practice is in this industry.
Does it matter? I mean, really matter?

Who here bought or built a model based on it's claimed weight? Did you pass up buying a Whizbang444 because it was advertised to have a flying weight of 986 grams and bought a P2K because the box said it weighed only 921 grams (or whatever)? Show of hands. As I thought, I don't see anyone raising their arm.

Is the advertised weight a benchmark to accomplish in your build to achieve the stated performance? Oh, wait. They don't give any performance data so it's hard to miss the missing mark. I suppose it would be important if you planned to enter it in a contest limited to electric motor gliders weighing not more than 1Kg, but I've never heard of anything like that.

I think we buy or build a model because we think it looks kewel, or has the flying characteristics we want (glider, heli, 3D, EDF, super scale, etc.), or fits our current budget, or fits in your car, or any number of other reasons, but I think weight is not a consideration.

My beef is with manufactures who put forth a model that won't even fly without major modifications. Things like design and engineering failures such as not being able to achieve a flying CG when built to specification, designed rigging that results in controllability issues, severe structural deficiencies, or PNP and RTFs that won't even fly due to lack of power or inadequate control authority.

Just my thoughts on the subject.

Ted
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Old Apr 21, 2012, 12:19 PM
CURIOSITY Has Landed!
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Agreed TED. I thought that was curious whinge too!
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Old Apr 21, 2012, 06:13 PM
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Originally Posted by StarHopper44 View Post
...I've asked previously for the OP/thread-starter for this P2K thread, but got no response. I wanted to recommend he either set up a similar 'Page 1' setup here, or whatever action so someone here (or we) could maintain it as that other thread I cited. What it boils down to is, making the 'Page 1' a kind've 'FAQ' section, specific to this particular airplane. If anyone knows a way we could initiate this - presuming we'd want to - I'd help any way I could.
I totally agree with you SH. Why don't we just go ahead and create one post here (let's say it's this post #1656 for example) that compiles an initial summarized list of mods and Basic build steps that one of us can edit and then have the OP just link to that post (#1656) on his post #1. I think a few of us (since we're pretty active on here) would certainly qualify to be able to maintain that post and if whomever that is gets tired of being the one to maintain that list, someone else willing can take over and that post can be edited and moved over, and then a pointer can be added to point to the new post location. The Aurora 9 thread does something like this.

I would be happy to volunteer to get this started if everyone is OK with this, and if I miss something, or you guys would want something changed, I can edit it.

In my spare time, I might also re-write the P2K manual to something actually useful in a PDF format and we could add that document to the thread too. I can edit this post (#1656) to be "the one" post to link to from the OP's first post. :-)

What does everyone think? Let me know and I'll get it started.
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Old Apr 21, 2012, 11:04 PM
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Well im happy to report that i maidened the Phoenix without incidents.. it was a 100% slope soaring day winds on the 25-30km/h (more than enought for any glider) so i didnt used the motor at all... plane left slope straight and up not veering and stable..

-CG was ok with the 2S 2200 (130g) in the rear part of the battery try.. despite my issues with the CG i can tell the CG was slight tail heavy in the marked spot in the plane.. when doing the dive test it didnt stabilized itself wich means a slighty rear CG ... that means that for slope i can use the 3S 2200 as it would put it a bit nose heavy wich is better for slope soaring when wind allows

-Plane flew really well in the slope tought wind penetration was not spectacular.. that might be because i flew the plane slighty tail heavy and in the light side... putting a heavier battery should improve performance in the slope making it faster and more stable..

-Aileron authority was ok for flying but clearly inadecuate to do rolls ..its more than enought to fly arround and handle the slope but i couldnt perform a single clean roll.. tried 2 times and both ended in a unholly abomination of maneover .. in the near future with a more complex radio i might use all 4 ailerons to roll wich should help.. still this is not a plane for acrobatics i guess.. its my wider plane with ailerons (i have another bigger 2m glider wich relies on dihedral for that) .. elevator authority on the other hand is supperb.. im amazed how nice this will pitch up and down even with almost not air to handle.. rudder authority is just fair tought not much effective..

-It was fun seeing the plane pass the slope in a speed pax with the wings slight flexing... i take this is normal

-Tried the flaps, reflex and crow airbrake.. they all seemed to work , flaps made the plane able to climb almost indefily in the slope.. also slowed it to a stop.. reflex did increased the speed tought wing flexing was way more notable.. i have little flap up in the reflex but maybe i should try less ..or try using the exterior ailerons rather than the inner flaps.. had a funny issue with crow airbrake.. i tried at altitude to see what the plane did with it and it made the plane pitch up almost vertically.. found that it was my fault.. i had mixed elevator with airbrake and did it the wrong way (i put elevator up instead down).. once corrected crow airbrake seems to stop the plane quite well

-Found also how hard is to hold a nylon fuselage when about to throw it down a slope with 30km/h wind coming at you.. never had that problem before

My conclusions:

-Slope can use heavier batteries.
-Do not think about doing victory rolls
-It doesnt retain much energy in the slope .. tought that can be due to me using a light config.. will have to try with more weight if the wind allows

I will order probably couple of batteries .. one nanotech 1000 30-50C (as the 2836 drains arround 30A at WOT) for thermic and no-wind soaring and maybe one 1600 for all-rounder
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Old Apr 22, 2012, 01:16 AM
Reap the wild wind
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Bristol,UK
Joined Feb 2007
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Very thorough report of the model's slope credentials. Of course, having that motor up front helps you get out of trouble if it's gusty especially around the landing phase. I once had an all balsa 2m glider (no power) which stalled at low altitude when a gust of wind hit it. With no motor to pull out of it, it just smacked into the unforgiving earth. Result - right wing sheared off. My fault as it was too windy for the wing loading and wasn't at all suitable for the conditions. Ended up converting to electric and sticking a 2nd hand Alpha 180 wing on it.
Winds here forecasting to gust to 25 mph so I think my Blizzard will have it's first outing of the season. Just a touch more power than my Phoenix
Andy
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Old Apr 22, 2012, 01:47 AM
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France
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Originally Posted by JLT_GTI View Post
...
Hi JLT_GTI, congrat for your maiden, this report seems really consistent on phoenix capacitites.

Except maybe for the GC part , maybe you should do the dive test in neutral conditions because to obtain the correct reaction to this test I set it to 83mm. To achieve this, the battery holder need to be modified to allow the battery to be moved really back, right below the plastic bridge between canopy & wings opening. I use 1800 3S lipo.
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Old Apr 23, 2012, 09:47 AM
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What not to do on your first flight!

Hi All, and thanks for all the info - I enjoy reading this thread and thought it high time to start contributing!

My first post will be long and embarrassing to write. But I want to go in to some detail to show not just the mistakes I made, but how I made them, and what lead me to them. My hope is that through my embarrassment, others will learn and not repeat the same mistakes. And for those who already know it all, just sit back and get ready to laugh!

The build and first flight of my Phoenix was a VERY rushed one last Christmas. I was a new fearless flyer who had just landed his Mini-Swift at the top of a 30m tall gum tree and for the first time had no plane to fly and no plane to FIX! I woke up to a perfectly calm sunny day, and as you can imagine, itching to fly. Without a plane I decided to build up the Phoenix which had arrived a few weeks earlier, but I was saving until I had more experience on the little Mini-Swift. The jump from 600mm to 2000mm was a little daunting, but what was I supposed to do? Play cricket instead!?

So I found this thread and scanned for some tips but could see myself spending the whole beautiful day inside reading a computer screen rather than out flying! From my rushed research I had determined that a 2200mA battery could be mounted in the middle of the tray, don't use the motor too long, and Crow or Flaperons were needed to slow the plane down for landing! By the time I had finished the build and figured out how to program flaperons (silly stock 9x firmware), it was late and the sun was setting. So I put the battery in the 'correct position' and did a rough CG check with my fingers and it was close but a little forward of the marks.

In hindsight, and these may be very obvious to most reader here, but may help another beginner like myself, I made two very big mistakes with my first flight:

1. No power-off glide tests to confirm a nice long slow glide - it is a glider after all! This will confirm that the CG is roughly OK and allow you to trim the elevator. You can also try out the ailerons and see how much authority they have and if necessary you can increase throws. Tip: When you arm tires from throwing, practice using a short blast of 50% throttle to get the plane going enough for a glide test.

2. Use of untested flaperons for landing - the first flight was in a fairly cramped field so I was banking on Flaperons to apparently 'slow the plane down for a nice short soft landing'. Of course I would test how they worked '3 mistakes high'! I had NO idea of how much Aileron deflection to use for Flaperon (not many people document seem to document their throws), but obviously MORE would be better right!

The result of the above two mistakes made for a CRAZY nerve-wracking first flight! It started off promising with the plane climbing strongly, but things stopped being fun once the motor was cut and it went into a steady FAST downward glide. I tried to trim the Elevator to flatten out the glide but found to my disbelief that I had just ran out of UP TRIM!! I now had a fast plane losing altitude quick with what I found to be VERY poor Aileron authority - the turn radius was huge!

CG was too far forward and the elevator trim was too small to correct it. A local Brown Falcon came out for a quick look and quickly turned it's head in disgust. I was constantly using throttle to regain lost altitude and I was getting conscious of the dreaded 'motor overheat'. I brought it round for a landing run and took a punt and flicked the 3-pos switch to flaperons. The travel it seems was way too much causing the plane to aggressively pitch up and stall. Meanwhile I was battling with Aileron control as the plane was now turning in the opposite direction to my input! I was in an unwanted turn, pitching, stalling and rapidly losing height! I fumbled for the hard to reach 3-pos switch, but there was no time to find it now so with flaperons still deployed I hit some throttle as a last ditch effort to get some more height. The result was instant vertical and an equally quick stall just 5m or so above the ground! I knew it was all over and watch helplessly as it nosed in vertically!

Lessons learned on first flight:
  • Phoenix is fast with a nose-heavy CG and insufficient elevator trim.
  • Proper CG and correct elevator trim are your friend.
  • Don't trust someone else's pictures of where they put their battery as it seems that not all Phoenix's are the same!
  • It might be long walk each time, but it pays to do some glide tests before first flight (even if the sun is setting!).
  • Find a big field with room for a long landing glide and forget about flaperons on your first flight.
  • Flying with the sun low makes it difficult to pick plane orientation when banking as plane is a silhouette.
  • Adverse Yaw, unknown to me at the time, is a very real problem with downward aileron deflections on this glider. Avoid using too much travel for flaperons or your plane will appear to have a mind of it's own!
  • Practice flicking your flaperon switch over and over so in a panic you don't miss it.
  • Make sure flaperons are off before using the throttle!
  • Ailerons need plenty of throw.
  • Ply wing joiner will break and wings will tear at the small rear mounts and the fuselage will buckle if you nose in hard enough.

I hope to follow this up with some shorter 'What to do' type posts in the future.
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Old Apr 23, 2012, 02:21 PM
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France
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I made a leek the for the maiden (I modified the GC after this), I made another leek for the first flaperon attempt (now I Iands without anything) & I also made a superb leek for the first sloping session.

So maca55, sorry to read that, but it's the life of all beginers, but once lesson will be learnt, you will take big pleasure with it, like all of us.
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Old Apr 23, 2012, 04:32 PM
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Originally Posted by traumkumy View Post
I made a leek the for the maiden (I modified the GC after this), I made another leek for the first flaperon attempt (now I Iands without anything) & I also made a superb leek for the first sloping session.

So maca55, sorry to read that, but it's the life of all beginers, but once lesson will be learnt, you will take big pleasure with it, like all of us.
I assume "leek" = "nose dive"?
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Old Apr 23, 2012, 09:30 PM
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Originally Posted by maca55 View Post
..

.
the adverse yaw can be remedied pretty well with aileron differential.. i allready set mechanical differential advancing the servo horns a bit forward.. but also dialed 20% electronically in the radio.. the result seems to work .. tought in the tries of a roll it was a dissaster.. tought i atribute that to the slope flying .. plane had not enought airspeed when trying a roll and this plane being this wide and with a thin profile glider-typical will loose even more speed when doing such aerobatics..


Actually i found it on other maneouvers... loops are so easy thanks to this plane fantastic elevator authority but if you try a pure slope wide roll you will notice it looses speed quite fast at the end of the maneouver.. maybe more weight will improve that in the slope..


Im lookin forward to weather improving (its been raining non stop for 20 days with only 2 part day stops, one of them for the maiden.. now that was luck) so i can try this plane thermal capabilities..


Also to order the light batts for it.. the problem is that in 1000mAh this needs the battery to be 30C nimimun with 40-50C to be on fair side (i have had 2200 20Cs get puffy in 27-28A loads),. i guess i should go with the nanotechs
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Old Apr 24, 2012, 01:33 AM
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France
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Originally Posted by eosglider View Post
I assume "leek" = "nose dive"?
Your assumption is right, nose planted into the ground, when the glider looks like... a leek.
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Old Apr 24, 2012, 04:21 AM
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"Make a Leek"

traumkumy, hearing about your "Leek Farming" experiences has made me feel much better. I really like the term 'make a leek'. Is that a literal translation of a French RC phrase? Beautiful slope soaring by the way!

Fortunately my Phoenix fuselage was easily pushed back and smoothed into shape again with a heat gun. Some epoxy on the ply joiner and some foam glue and fibreglass tape had the Phoenix wings back in shape quickly. After making my first leek I decided to get the plane trimmed and CG sorted by doing many many glide tests across a Soccer field. (My new found patience was in part due to having a second plane to fly, having finally rescued my Mini-Swift from the tree.) Apart from getting very fit, I learnt a lot about how the plane handles and how slow I could get it to fly. The glide tests also let me fine tune the Flaperon settings and apply some elevator correction.

I found myself moving my batteries, ESC and RX, further and further back! The 2200mA is now almost in contact with the servo frame. The 1600mA not so extreme. All this and I am still far from neutral stability in a glide test. I will measure my 'current CG' and report. I believe is is around 76mm. I am excited to hear of someone using a CG of 83mm as I still feel that my Phoenix should be able to float better.

As others eosglider and StarHopper44 have commented it is puzzling how many appear to be able to use the battery tray fine with no over hang, so I wonder whether there is some weight variations between models. Not overall weight so much, but perhaps a variation in the distribution of the plastic in the fuselage?
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