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Old Dec 03, 2011, 07:04 AM
Pullin' G's Man
cmoulder's Avatar
Ossining, NY
Joined Dec 2005
1,005 Posts
Thanks, Peter

It was indeed very tedious work!!

Very satisfying to have completed it.

Discovered night before last that there were no aileron horns (err... bolts) in the hardware package. Picked some up yesterday at one of the few remaining hobby shops that the economic recession hasn't killed off. Also got some good 5-ply for the motor box because all I had on hand was some crappy 3-ply.
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Old Dec 04, 2011, 06:34 AM
Pullin' G's Man
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Ossining, NY
Joined Dec 2005
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Peter,

I need to make a correction.

After beginning work yesterday on the motor mount it dawned upon me that indeed the firewall DOES NOT have any right thrust built in. And after looking at it even more, I'm pretty certain it also doesn't have down thrust either.

I decided to take a different approach to the motor mount. I don't know how well it will work, but I am combining a couple of ideas I got from assembling pattern ships: 1) using a "sliding" pair of motor mount "wings" inserted into slots in the firewall, as was the design on my old Focus II, and 2) using a temporary front mounting of the motor to the cowl to get the alignment right and hold it in place, and then spot gluing the "wings" from the back of the firewall to set the position.

Once the alignment is confirmed, further reinforcements can be added to the motor box. The nice part about this (IF it works) is that the motor can be tilted up/down and left/right and also moved up and down relative to the firewall, and there is no need to finagle with stand-offs.

The photos show the motor mount and the side "wings", which turned out to be too large for the firewall and had to be reduced in dimension. However, much better to have to remove material rather than add!
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Old Dec 05, 2011, 12:50 AM
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Newcastle, New South Wales, Australia
Joined Sep 2007
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Bob,
I love your "out of the box" thinking with your motor mount and am looking forward to seeing how you handle getting the 3 axis plus down and side thrust right all at the same time. You're a better man than me!

I actually got mine out on Saturday but was disappointed that my Hyperion speedy and Himaxx motor have decided they're not friends anymore! I can't figure out why the sudden falling out since they have been cooperating for years. Maybe it was always been a shaky friendship and I just haven't noticed it....

Anyway good luck with your motor mount, just be sure to take some photos so I can steal your ideas!
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Last edited by Peter M; Dec 09, 2011 at 07:02 PM. Reason: spelling
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Old Dec 05, 2011, 06:54 AM
Pullin' G's Man
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Ossining, NY
Joined Dec 2005
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Peter,

I made a lot of progress yesterday, which was the first full day I've been able to work uninterrupted without work and family obligations. Made a lot of progress and likely will be able to maiden later in the week or next weekend if the unusually mild weather hangs around a while longer.

The motor mount idea worked pretty well although my alignment was off just a bit and forced me to give it a skosh more than 2 deg right, perhaps 3 deg, which is fine because I will be using a 20.5x14.5 prop, and with such steep pitch it might just be spot-on. Down thrust was just a little. In any event, it is a sport flyer so I don't mind ironing out any trim issues with Tx mixes.

Your model looks great! I love the classic lines and the open cockpit, and the fact that it's not another Extra or Yak. I have flown so much pattern practice that I need a break to fly something that is totally different, and just for fun.

I am taking photos as I go along and will post more later.

BTW, I thought about the weight issue with the Heavy motor and ESC up front and decided to put the rudder servo in the tail, so now there are 3 servos back there to hopefully balance things out. I will be able to do the first critical "CG read" tomorrow and definitely will have fingers crossed on that one.

As you and others have noted before, the landing gear really is sub-par. But it will suffice for now and I will ponder other options. But the wheels did stick out too far and I decided to cut the axle sections from the stock gear and used some slide-on replacements that permitted positioning the wheels in a more concealed manner.
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Old Dec 06, 2011, 11:31 AM
Pullin' G's Man
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Ossining, NY
Joined Dec 2005
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Quick question: What is the CG from the leading edge of the wing at the root?

Best I could figure from the still-errant (apparently) instructions, it should be 11.5cm at the root, not the tip as indicated.

However, it seems to me a bit too far forward at 11.5cm measured at the root.

-- Bob
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Old Dec 06, 2011, 01:54 PM
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Newcastle, New South Wales, Australia
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Bob,
I would still suggest you start at 11.5 cm from the wing root rather than the wing tip. You can always move it back by adjusting your battery position in later flights.

http://www.rcgroups.com/forums/showp...4&postcount=53

Regards
Peter
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Old Dec 06, 2011, 04:59 PM
Pullin' G's Man
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Ossining, NY
Joined Dec 2005
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Thanks, Peter, that's what I'll go with to start.

-- Bob
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Old Dec 09, 2011, 05:07 PM
Pullin' G's Man
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Ossining, NY
Joined Dec 2005
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Peter and fellow Sparrow Hawk fans,

Got mine finished and was able to maiden today, plus 5 more flights.

This is really one great flying model! Much lighter on the wing that I would have suspected and, as Peter mentioned earlier, it lands a little fast but not terribly so, and there was no tendency to tip stall at "reasonable" speeds.

The plane can fly fairly precisely and needs only a little aileron differential for axial rolls, and some mixes for knife edge (a lot of elevator mix) and maybe some aileron. But I did not do any mixing at all today, just wanting to fly it around and get used to it. The rudder is surprisingly effective and didn't take nearly as much as I thought would be required for knife edge.

I must admit I started out with the CG at 13cm and it was excellent In My Humble Opinion. I couldn't resist because 11.5cm plainly looked too far forward for such a wing. Inverted flight required only a bit of push, and the model was very stable inverted.

Upon landing after the first flight, one of the wheel collars came off and there was some minor damage to one of the landing gear fairings, but that was the only indignity suffered all day.

The Himax 6330 and 10s 5000mAh battery is a great combination. Gobs of power, but not to the point of silliness. Full power low passes looked just right on speed.

All in all, a great model and thanks go to Peter M for leading the way on this conversion project, which is my first.
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Old Dec 09, 2011, 07:04 PM
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Newcastle, New South Wales, Australia
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Congratulations!

Well done Bob!

The thought and effort you have clearly invested has paid off handsomely!

Regards
Peter
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Old Dec 09, 2011, 09:25 PM
Pullin' G's Man
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Ossining, NY
Joined Dec 2005
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Thank you, Peter.

On many occasions I referred to your photos and descriptions from the first few pages.

Makes me want to try another conversion. Some day. But not right away!!

-- Bob
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Old Dec 10, 2011, 08:35 AM
Pullin' G's Man
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Ossining, NY
Joined Dec 2005
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A more nostalgic look, courtesy of Photoshop.

-- Bob
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Old Dec 11, 2011, 04:21 PM
Pullin' G's Man
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Ossining, NY
Joined Dec 2005
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After horribly windy weather yesterday, today was a real gem: temp of around 40degF and a light breeze from the south, perfectly parallel to the runway. Can't ask for much more than that.

Got in 5 quick flights today because I was the only one at the field. Main purpose was to have fun, but also get the KE mixes figured out. Spent one flight working on this and now have No-Right-Hand KE (In Mode 2, that is!) for both right and left KE. It took 17% up elevator for left top rudder and 39% (YES, 39%!!) for right top rudder. However, there was absolutely zero aileron coupling on either side, and now the model will do no-right-hand KE's from either side, horizon-to-horizon. Makes for some very nice 4- and 8-point rolls and slow rolls.

Also was able to download all the data from the 5 flights into CC Data Log to find out what the electronics were up to. Discovered that I'm not pushing the systems at all. Max current draw for all the 5 flights was 65.8A and max Watts was 2242, this on a very aggressive flight of a bit more than 7.5 minutes. Recharging the battery for that particular flight with a Cellpro 10XP registered 3370mAh put back in. So there's plenty of cushion on the flight time. I did one flight where I tried to keep it sedate and "scale" looking, which led to a max current draw of 54 amps and average current draw of 9 amps with max watts of about 1600.

I am learning better how to land the plane. It really glides and therefore favors a long, shallow approach with a little throttle to tweak the glide path and steady elevator feed for a nice soft touch-down.

Although I wanted to get some video today, it wasn't possible as I was alone, but perhaps next time.

The more I fly the Sparrow Hawk, the more I like it!
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Old Dec 11, 2011, 04:59 PM
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Fayetteville, AR
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I gotta say, that's some nice grass on that field!

What kind of flight times are you getting with the 10s 5000mah?
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Old Dec 11, 2011, 07:46 PM
Pullin' G's Man
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Ossining, NY
Joined Dec 2005
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Quote:
Originally Posted by bicyclemonkey View Post
I gotta say, that's some nice grass on that field!

What kind of flight times are you getting with the 10s 5000mah?
The field is at Hudson Valley Radio Control Club in Haverstraw, NY. The grass is immaculately maintained by Club President and all-around dynamo Bruce Leach, who cuts it frequently, fills gaps and seeds them, rolls it after every rain (when the underlying clay is soft and malleable), and chases away the geese that love to leave huge, uh... deposits. It is located on top of a land fill - as are many flying fields in these parts - so it looks excellent considering that it's a real dump.

I am gradually extending flight times. I started out very conservatively with 6 minutes on the timer, but I actually get more flying time than that because I have my throttle stick programmed to start the timer, and it pauses it when the stick is in the idle position. So on downlines and other times when the throttle is at idle, the flying time is not counted. However, today I flew another 1.5 minutes past the 6-minute warning and still had a fair amount of battery left. So now, after 11 flights and judging the condition and remaining battery capacity, I would be comfortable setting my timer for 8 minutes, which would probably give me 9 or more minutes of actual flight time depending on time at throttle idle.



-- Bob
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Old Dec 11, 2011, 09:40 PM
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Fayetteville, AR
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That's cool, how did you program your radio to pause the timer while at idle? Or is that feature specific to your TX?
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