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Old Aug 19, 2007, 08:06 AM
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dick hanson's Avatar
slc ut
Joined Nov 2003
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these large flat foamies outperform any of the pretty built up smaller stuff -
I have two "scaleups" each at about 430 squares and all up weight using 2100TP packs of 16 on the SS and 20 ozs on the Thing.
wing loading is under 7 ozs in either case
the white unpainted one is powered by a 480 EFlite the Super Star - a Hacker 20-20
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Old Aug 19, 2007, 08:15 PM
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Annapolis, Maryland USA
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Flight Report

Went out this morning to give her a try with better batteries and of course the
Sombra Labs Shadow 3 super duper wiz bang cant be shot down receiver kept dropping out , seemed fine last time.
Swapped in a spare and brought a conventional RX on the evening attempt.
All seemed well so I gave her a toss. This flight was on 3S2P 1700 20/30C paks and she flew nicely and probably 12+ minutes. However, vertical was mininal and she definitely required some airspeed to fly.
Late in the flight I decided to try some full rudder flat turns and was stupified to find out that about half way around she rolled over into an uncommanded spin in the opposite direction. After about 3 confirmation attempts I decided it was for real. WOW, I've never had a plane do that.. its well, like a real airplane would do
Next I tried one of my old 2100 15/20C paks again(found last attempt, the charger I used turned off at 12.05v, just over half charge) she flew MUCH lighter
but the pak has about had it.. she faded in about 2 minutes
Next up was its sister pak, this one gave me about 6 minutes and I came down a little early. Noteworthy was the TOTAL absence of the tendancy to spin out of flat turns.. she just turned. KE was much nicer cause it flew much slower. Hovering was much easier too but still very marginal power.
Last up I tried a slightly puffy 1700 like above but by itself...this produced a
significant rearward shift in CG but it was barely noticable in flight,,2 clicks trim took care of it.
Again, weak vertical but she flew even nicer on the wing and seemed to like high alpha.
What surprises me is whole range of weight I tried is only 5 oz. With 10oz of battery she was clearly too heavy to feel nice. With only 3.3oz less she was a different bird despite identical CGs. With 2 oz less yet and aft CG I was thinking I would probably always fly this one on high rates even thought it was quick even on low rates...hard to explain but like the ad says, its precise - so much so you can handle more than usual control authority.
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Old Aug 19, 2007, 08:37 PM
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3D World, Florida
Joined May 2005
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Strange little flight tendency,huh? Haven't seen that one in mine. Curious as to what makes that happen. At least you got some flight time in, good goin'! KE's are a blast, hardly any rudder input is needed(until it's time to do a KE loop!). I'm making some more VG's this week will post pics when done, these really do make a difference with the slow flight characteristics. On the down side they also soak up more amps. I'll probably give myself about 200 watts per lb on the next version just to have a little headroom.
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Old Aug 19, 2007, 11:04 PM
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Annapolis, Maryland USA
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The spin is most likely just a result of just plane too high wing loading, the direction change makes sense too as there is some counter aileron involved in keeping the turn flat not to mention torque as I alway turned to the left

I ordered a speed controller for my 600w Axi...but hopefully the right prop and a few more amps will get her done with the current motor I have both Graupner and APC 13 and 14 inch 4 pitch props coming and a 100amp wattmeter on their way so I'll get there
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Last edited by crossup; Aug 19, 2007 at 11:11 PM.
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Old Aug 20, 2007, 12:23 AM
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3D World, Florida
Joined May 2005
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Hmm, my plane is more of a pig than your's but hasn't shown any spin tendencies. Hey it never hurts to add some more watts! At least not in this plane. 500watts seems like just enough to be fun More power certainly wouldn't hurt my feelings.


Quote:
Originally Posted by crossup
The spin is most likely just a result of just plane too high fun on my plane. A few more watts wouldn't hurt my feelings eitherwing loading, the direction change makes sense too as there is some counter aileron involved in keeping the turn flat not to mention torque as I alway turned to the left

I ordered a speed controller for my 600w Axi...but hopefully the right prop and a few more amps will get her done with the current motor I have both Graupner and APC 13 and 14 inch 4 pitch props coming and a 100amp wattmeter on their way so I'll get there
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Old Aug 20, 2007, 01:00 PM
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we THINK your plane is heavier, however this would not the first time a bunch of extra weight snuck into one of my planes...
I dont have a scale that will weight it assembled but my best guess is I flew at up to 39oz and 34 oz at the lightest
I'm holding out for a scale that will go to at least 25 pounds as I have some IMAC builds to do
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Old Aug 20, 2007, 03:02 PM
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3D World, Florida
Joined May 2005
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I started out with a bare 14oz foam airframe that ballooned up to 42oz fully loaded. Oh hell, try as I might the oz. have a way of multiplying. At any rate I've determined that this plane needs the weight and the watts so I'll power the next version accordingly. Noticed Scorpion has added some more motors and are advertising up to 85mm motors coming soon. I think they might be the cost effective solution to bigger more fun birds. I've got them saved to favorites for sure!

Quote:
Originally Posted by crossup
we THINK your plane is heavier, however this would not the first time a bunch of extra weight snuck into one of my planes...
I dont have a scale that will weight it assembled but my best guess is I flew at up to 39oz and 34 oz at the lightest
I'm holding out for a scale that will go to at least 25 pounds as I have some IMAC builds to do
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Old Aug 20, 2007, 04:16 PM
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Cheers for the info lads and keep the discussion rolling... this is very educational!

Russ.
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Old Aug 20, 2007, 05:10 PM
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Roseville, CA
Joined Aug 2006
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All this talk of watts...hmm, makes me wonder if my motor choice was the right one?

I picked a Scorpion 3008-32 and a 40a ESC for this plane. Prop data suggrsts I should be approaching 300w, 3S perhaps on a APC SF prop in the 12-13" range, low pitch range. I haven't sent a single amp into this motor yet but I'm wondering now if I should exchange it for a more powerful motor.

I don't know what the AUW of my 44" version will be but I've been guessing at 22-24oz. I'm thinking I'll be safe and guessing at the upper thirty range of thrust. The data on props dosent show much on the low pitch SF props so I am guessing the performance at this point.

What do you guys think?
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Old Aug 20, 2007, 05:51 PM
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3D World, Florida
Joined May 2005
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If you're getting 300 watts on a 1.5lb plane that should do the trick. 12-13" prop should be about right,(I like the 1/4+ prop:wingspan theory for 3D). I'm about 185watts/lb or so and that's just marginal. OK vertical-could use a little more IMO. I would think around 200 watts/lb would give better than satisfactory performance. My 2 cent deposit.
Quote:
Originally Posted by ToxicToast
All this talk of watts...hmm, makes me wonder if my motor choice was the right one?

I picked a Scorpion 3008-32 and a 40a ESC for this plane. Prop data suggrsts I should be approaching 300w, 3S perhaps on a APC SF prop in the 12-13" range, low pitch range. I haven't sent a single amp into this motor yet but I'm wondering now if I should exchange it for a more powerful motor.

I don't know what the AUW of my 44" version will be but I've been guessing at 22-24oz. I'm thinking I'll be safe and guessing at the upper thirty range of thrust. The data on props dosent show much on the low pitch SF props so I am guessing the performance at this point.

What do you guys think?
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Old Aug 20, 2007, 05:55 PM
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Annapolis, Maryland USA
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without knowing the weight its pretty hard to be more accurate, but EDF is saying 200w/lb seems about right for this design so at 24oz or 1.5lbs 300w should be just right
Personnally, I'm not gonna sweat it, I'll try to improve what I have and failing that I'll drop in some more horsepower.
But I know from experience, props make all the difference. I've had a plane almost not fly on a MasterAirscrew 18x6 and then go to a Mejlik 18x6 and the plane is ballastic.
So I'll be swappin' props and watchin watts
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Old Aug 20, 2007, 06:25 PM
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3D World, Florida
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That's the ticket, I went thru about 4 props before settling on the 13 x 4. Want to try out some Xoar props but my LHS hasn't gotten them in yet. Those should be even quieter and more effecient due to less flex. I'm going to be doing a giant scale 3D bird next so you can bet I'll be trying out the 22-24" Xoars first to get the size right and then a Mejlik. Getting a little tired of all the flexing and noise of the APC's.
Quote:
Originally Posted by crossup
without knowing the weight its pretty hard to be more accurate, but EDF is saying 200w/lb seems about right for this design so at 24oz or 1.5lbs 300w should be just right
Personnally, I'm not gonna sweat it, I'll try to improve what I have and failing that I'll drop in some more horsepower.
But I know from experience, props make all the difference. I've had a plane almost not fly on a MasterAirscrew 18x6 and then go to a Mejlik 18x6 and the plane is ballastic.
So I'll be swappin' props and watchin watts
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Old Aug 21, 2007, 09:13 AM
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Roseville, CA
Joined Aug 2006
624 Posts
Pull pull woes.

First time with a pull-pull.

Rigging the rudder, ATM. Horns are about 1.5cm off the rudder surface. Ran 10lb spiderwire brand mono (I think this is the problem), tied with bowline knots at the horn. Connected to 1.5" homemade pins (piano wire bent with a loop at the end) that feed to EZ connectors at the servo arms.

Unless it is pulled super tight (the mono seems to stretch quite a bit, which is why I think I bought the wrong kind), the rudder has a ton of slop when I wave the airframe around. When it is super tight, the strings make a decent guitar string sound, and the rudder either snaps to the right or left and will not equalize.

I think the problem is the fact that the mono is not a braided line type, it stretches quite a bit. Any suggestions before I trek back out to the tackle shop and look for somethign more suitable?
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Old Aug 21, 2007, 10:00 AM
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USA, OH, Cincinnati
Joined Dec 2003
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Toxic - I have used Berkley Gorilla Tough super braid fishing line (20 # test) for my pull-pull and it doesn't stretch a bit. Just tie the line in good tight knots and put a drop of CA on them to be sure they don't pull out. For the connectors I used long shank fishing hooks and cut off the curved barbed parts. This gives you a nice straight wire with a built in loop at the end. You can get fishing hooks in different sizes so you ought to be able to get one the correct diameter for the hole in the EZ connector on the servo arm. Good luck!
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Old Aug 21, 2007, 11:05 AM
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Annapolis, Maryland USA
Joined Feb 2001
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You're having a problem with tightness is because your rudder control horns don't come forward to the hinge line. Think of it this way: you want the hinge to be the axle or pivot and the control horn eyes or holes need to draw a straight line from hole thru the pivot or hinge and the other hole. This is how your servo arm works and the rudder end needs to duplicate the geometry of the servo end, precisely.
And yes, mono line is stretchy, you definitely want braid or layed line.
Using CA to lock knots works but does make a hard spot that will be the first place to fail in the line (actually immediately adjacent to the hard spot)
I see you did double bevel the rudder, thats good, hinging from one side does throw off the geormetry a tiny bit...I used actual hinge points on my XL ruddder
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