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Old Jun 15, 2002, 08:54 PM
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Darn Servo !'s Avatar
Joined Dec 2001
217 Posts
757 Toy Styro jet flies with Authority!

I was about ready to give up after my first attempt at getting one of these gliders to fly...But I didn't.

All I have to say is this thing flies great!

2 - 370 motors
2 - Zagi props
6 cell ni-mh AA battery pack (1500mah)

It flew right out of my hand and trimmed out great. It even flies at less than full throttle.

Compared to my last attempt, this plan is awesome!

Critical attributes (My guess):

-Motor squareness (thrust vector line)
-Wing dihedral

These attribute are what I paid more attention to on this iteration... It seems to have paid off.
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Old Jun 15, 2002, 08:55 PM
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More pics

More pics
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Old Jun 15, 2002, 08:56 PM
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Even more

More pics
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Old Jun 15, 2002, 08:57 PM
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Last pic

Last one...
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Old Jun 15, 2002, 09:43 PM
Giddy up!
Sal C's Avatar
Woodridge, Illinois
Joined May 2000
4,478 Posts
Very nice! I like your motor mount method. I have one I started, I'm going to have to get back to it. Nice job.

BTW, did you just use strapping tape for spars or did you add something underneath?
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Old Jun 15, 2002, 09:55 PM
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217 Posts
No Spar...

Hello Sal C,

I didn't use a spar, just the strapping tape. I just glued in the wings then I filled in the joints with clear RTV (actually I forced it into the joints with my finger). It really is sturdy.

As for the motor mounts, I struggled a long time on how to do this. The brass strip worked out great.

The plane really has a nice feel to it, it has a nice return to center effect. I am really surprised!
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Old Jun 16, 2002, 07:19 AM
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Aspen's Avatar
Kingsport Tn.
Joined Nov 2001
535 Posts
Good job! I've had the motors and plane for several months but have been putting off building it because I didn't have a good motor mount method. I didn't want to just glue them in, and had about decided to use 35 mm film canisters. I like your method better.

You say wing dihedral is critical. Can't tell from the pictures, but it looks about normal. How much did you change it? Also, did you wire the motors in series? Thanks.

John
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Old Jun 16, 2002, 07:45 AM
small electrics r BIG FUN
Iowa
Joined Aug 2000
4,320 Posts
Nice conversion, good looking plane. Would love to see some in-flight photos !

Al
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Old Jun 16, 2002, 09:16 AM
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Detroit
Joined May 2002
4 Posts
Goal Post Video

Servo, how about posting the video of the Crazy Sparrow getting up close and personal with the goal post? Hmmm?
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Old Jun 16, 2002, 09:25 AM
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About the Dihedral

I didn't modify the dihedral at all. What I did on the wing was to make sure the dihedral was equal on both sides. On
my last plane, I noticed that one wing was a bit lower.

For the motor mounts, I used 2 hole saws. I drilled out the outside diameter first and
then I drilled out the inside hole. I used RTV to attach the plywood plate to the
styrofoam.

The hardest part had to be squaring up the styrofoam on the front of the nacelle. I
used a square and razor to square it up.

I will upload in flight photos as soon as I can get some!

The motors are wired in parallel through a 5 amp ESC.
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Old Jun 16, 2002, 11:26 AM
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Crazy Sparrow getting up close and personal with the goal post

Hey Stallspeed,
That video will be on Pay-Per-View only.

And it wasn't a goal post, it was a jungle gym.


It can be pretty dangerous in those school yards...
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Old Jun 16, 2002, 09:37 PM
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Detroit
Joined May 2002
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My Bad

Sorry Darn Servo !, my bad. Hey, just wanted to let you know I put the Lithium-ion battery (7.4V, 1500mAH) in the Tiger Moth today. The extra 0.2v makes a noticable difference in performance. The extra RPM is needed to offset the additional weight, but seems to be a good trade-off. My first calculations say the moth will fly continuosly for 1 hour and 10 minutes! I'll have to drag the LazyBoy(tm) onto the front porch so I can be comfortable during extended flights. The extra weight seems to be stressing the wings a bit (variable dihedral during abrupt maneuvers), I plan to add support somehow. I think lithium is the ticket for the Crazy Max (not my son, the airplane you picked up for me) <---- get it? I made a charger out of an LM317 for the pack I made. It charges fine, but you have to watch for the current drop-off to figure out when to stop the charge. I'll have to add some kind of timer for convenience and safety. Didn't realize you flew the 757 already; nice job on the motor mounts.

Servo, forget lithium and the Crazy Max, way too much current draw from the motor! I'm adding the lithium battery to my styro glider (the one I picked up from Joe's Hobby) and plan to fly it in the morning. By the way, I had some trouble with the zagi prop spinning right off the 280 motor; added some superglue.
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Old Jun 16, 2002, 10:19 PM
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Joined Dec 2001
217 Posts
Lithium-ion battery

So when are you going to build up the Crazy Max?
I wonder how long it'll fly with the lithium ion batteries. Watch that 'variable dihedral'
feature, it's bound to show you the wing loading limitations when you least want to
see it!

I had about a 15 minute window of opportunity last night so I decided I couldn't wait
any longer and I had to see if the 757 would fly. Wow, It it was amazing, I only did
about 5 circles around the field when it started to rain and the wind picked up. I
thought for sure the thing was going to do the classic death spiral into the ground when the wind kicked up.
But much to my surprise, it handled extremely well. I wonder if the reduced vertical
stabilizer area minimized the cross wind anomalies. All I know is it can turn left and
right about the same with no unusual characteristics. Lots of power too, and it fly's
real fast!
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Old Jun 17, 2002, 08:45 PM
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In-Flight photos

Here they are!
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Old Jun 17, 2002, 08:46 PM
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Next shot

next shot
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