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Old May 28, 2008, 02:37 PM
Flashmeister Aviation Inc
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Joined Aug 2005
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Quote:
Originally Posted by BaldEagel
I will throw myself on my sword the next time I get it out to clean, as long as I don't hold it upside down.

Mike

lmao
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Old May 28, 2008, 07:15 PM
'FPV'er...not a "LOS'er
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Las Vegas, NV
Joined Sep 2003
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Don't be ashamed BaldEagel. That was an honest mistake and an easy one to make. Now if you really want to spice things up...start talking about up/down thrust on a pusher configuration with the motor in the back of the plane. That one confuses me to NO END!!!!
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Old May 28, 2008, 07:32 PM
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Cayman Islands, Grand Cayman, Patricks Island
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Lol thanks for all the replies, so too much down thrust, okay, so i don't get it wrong, that then means you back off the top left and top right screws on the thrust plate by i guess 1/4 of a turn and re-check in flight.

Regards

Dmac
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Old May 28, 2008, 08:07 PM
'FPV'er...not a "LOS'er
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You got it Dmac...back off the two upper screws a little. I'd go at least a 1/2 turn and then refly it.
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Old May 28, 2008, 08:20 PM
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Thanks Vantastic

Dmac
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Old May 29, 2008, 02:26 AM
Flashmeister Aviation Inc
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Joined Aug 2005
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erm dunno about the trimming screws because Im using the littlebirdz mount. As a rough guide I think Im on about 1.5degs down on mine ( just visible if you look closely from a foot or so away) although a few people I know run it at zero ..ie dead straight .

While we're talking about trimming, once you're happy with the thrust angles, try flying it inverted (quite high ) and it should fly hands off dead level or just need a fraction of down elevator to keep it in level. If it climbs skywards its tail heavy, if it pulls its nose into the ground then its nose heavy.
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Old May 29, 2008, 12:31 PM
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Quote:
Originally Posted by Vantasstic
You got it Dmac...back off the two upper screws a little. I'd go at least a 1/2 turn and then refly it.
Don't forget to screw in the two lower screws to take up the slack you have introduced, otherwise it will wobble about and introduce vibration.

I am sure that's correct anyway.

Mike
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Old May 29, 2008, 12:55 PM
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Quote:
Originally Posted by MrFlash
While we're talking about trimming, once you're happy with the thrust angles, try flying it inverted (quite high ) and it should fly hands off dead level or just need a fraction of down elevator to keep it in level. If it climbs skywards its tail heavy, if it pulls its nose into the ground then its nose heavy.
I also tried a different method to test CG. It was from a trimming guide. It said to bank the plane at least 60 degrees in a turn, then if the nose falls, it's nose heavy, if the tail falls, it's tail heavy. I can never get the tail to fall, even when I move the CG way back that it's obviously very tail heavy. (need up trim when flying up right and plane climbs fast when inverted) So does this mean the banking test is invalid or I'm just doing something wrong?
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Old May 29, 2008, 01:05 PM
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Quote:
Originally Posted by rcboosted
I also tried a different method to test CG. It was from a trimming guide. It said to bank the plane at least 60 degrees in a turn, then if the nose falls, it's nose heavy, if the tail falls, it's tail heavy. I can never get the tail to fall, even when I move the CG way back that it's obviously very tail heavy. (need up trim when flying up right and plane climbs fast when inverted) So does this mean the banking test is invalid or I'm just doing something wrong?
This sounds like a thrust issue rather than C of G, if you have up trim when flying upright that transposes to down trim when inverted, but you say you are climbing, this all points to excessive up thrust on your engine.

Try this for C of G checking, trim for straight and level first, pull to a 45deg up line, roll inverted and see what happens if the nose drops you are nose heavy, doing it this way takes out the thrust issues, when trimming an aircraft for aerobatics you must get the C of G correct first, its vital otherwise all other adjustments will have to be re-done if you adjust them first.

Mike

EDIT: to add link, this is the best trimming guide I have found, it is for aerobatics not 3D, but the principles are the same: http://www.flagstaffflyers.com/image...thTrimming.pdf
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Old May 29, 2008, 02:25 PM
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Quote:
Originally Posted by BaldEagel
This sounds like a thrust issue rather than C of G, if you have up trim when flying upright that transposes to down trim when inverted, but you say you are climbing, this all points to excessive up thrust on your engine.

Try this for C of G checking, trim for straight and level first, pull to a 45deg up line, roll inverted and see what happens if the nose drops you are nose heavy, doing it this way takes out the thrust issues, when trimming an aircraft for aerobatics you must get the C of G correct first, its vital otherwise all other adjustments will have to be re-done if you adjust them first.

Mike
I have a brand new AM with no adjustment screw just the motor bolted tight and I can see no thrust angles on the props. So I think the thrust is fine. I was just asking whether that banking method is valid test. Going from full throttle to 0 throttle also did not give me any abrupt up or down movement. The only time I needed to use up or down trim was during the banking test where I moved the CG way back. Once I moved the CG back to suggested 120mm, all those problems are gone. Except the bank test, hence why I asked if it's valid. I will try out the test you suggested and from the PDF this weekend as well. Thanks for the link.
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Old May 29, 2008, 03:02 PM
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Thanks for all the tips Baldeagle, rcboosted and Mr Flash, i will use them all.

Regards


Dmac
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Old May 29, 2008, 03:50 PM
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Saw a MultiPlex add in this months M.A.N. They're showcasing their Elapor line. Pic's of the funjet, EZ, Parkmaster, and others...but no Acromaster
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Old May 29, 2008, 07:18 PM
'FPV'er...not a "LOS'er
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Quote:
Originally Posted by stanordave
Saw a MultiPlex add in this months M.A.N. They're showcasing their Elapor line. Pic's of the funjet, EZ, Parkmaster, and others...but no Acromaster
That's because everyone already knows how great the AM flies!!!
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Old Jun 01, 2008, 01:06 AM
Squish!!! Splat!!!
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Maricopa, Arizona, USA
Joined Oct 2007
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Well, Guys, you can pin the dumb@$$ award on my lapel tonight. It's gonna be real hard telling you what I did. It's pretty embarrassing and I'm not sure how to go about admitting this. I'll start by exclaiming that it takes a pretty big person to confess what I have to say right now. <grin> That's how I'm going to label this, but I can hear the laughter starting already.

My new AM, with all your help, looked and felt perfect. It seemed like all of you were pulling for me to have a good maiden flight, and I did. So perhaps now you are asking what it is I did to have to go through this admission of guilt, or stupidity, which it really is. Here's the story (It's beginning to hurt already even before I get the first word out).

A week ago I was giving her a nice WWII paint job and I had to line up the design on the fuselage with those on the wings, so I stuck the wings in the fuselage. Two or three days later the paint was finished and all the adjustments and trimming was done and she was ready for flight. The very next morning I took her out and she maidened very well. Being timid I just took her around in lazy circles and brought her in with two very smooth and soft landings....couldn't have gone better. No hint of a problem, whatsoever.

So, the following morning, with a little more confidence (cockiness), I put her up in the sky and twisted the sticks around quite a bit. Then I brought her down in a swooping dive and back up to about 200'. Still climbing I hit the aileron stick for a roll and POP, something came flying off the fuselage. It looked like a wing as it fluttered to the ground. But the fuse didn't flutter. It came straight down like an arrow and buried the motor and nose in the softish ground. This happened in knee high alfalfa and it took nearly an hour to find her, but I recovered the two pieces just as dusk was turning to dark.

I didn't notice too much wrong at first, except for the damage to the fuselage when she hit the ground so hard. But when I got her home and pulled the other wing from the fuse it seemed that something was wrong, something was missing. Then it dawned on me that THERE WERE NO CARBON FIBER SPARS in either of the wings. I thought it would have been pretty difficult for them to have pulled out by themselves so I looked in the AM box. This is where it gets really hard to continue....THERE THEY WERE. I had forgotten to pull the wings out after the paint job to insert the spars. I'm wondering how the AM got through her maiden so well, and how she managed pulling those stunts for more than a minute before she came flying apart. So I get, and well deserve, the dummy award. Please make it swift.

She's all repaired, trued out and ready to fly again, AND the CF spars are inserted in the wings this time. I can't take her up tomorrow (Sunday), but I'm excited about getting her in the sky Monday morning. She flew so well as a cripple that I'm looking forward to some really good flying fun on her next run.

OK, ok, that's enough...you can quit laughing now. I'm sure some of you have pulled some good stunts yourselves. Maybe not as foolish as this one of mine, but enough so that I'm not completely alone. But, then again, perhaps I AM the only one with an AcroMaster who ever accomplished this kind of flub.

BTW, absolutely no damage to the wheel pants...go figure...!!!

FS
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Old Jun 01, 2008, 01:38 AM
Retired USAF
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USA, SD, Piedmont
Joined Jul 2005
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LOL...at least you can laugh at yourself! Story would have had a really bad ending if it was a balsa plane though--elapor lives to fly again!

BTW, my wheel pants will live forever too...especially since I took them off after the first few flights!
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