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Apr 15, 2007, 10:05 AM
Your ruler, in part...
Angry_Monk's Avatar
Discussion

My [Brushless] .98g plane


I finished building this plane last weekend, and as of yesterday it flys amazingly well. i kept it in the air from full charge until it wouldn't climb anymore and that was about a 4-5 minute flight. it is so quite! most of the time you can't hear it. it does have a tendency to turn counterclockwise a lot more than clockwise, but i have almost fully corrected the problem. one thing i will have to change, however, is to make the rudder smaller and add a little surface area in front of the hinge point because it has very little control authority. that is a fix i hope to have done soon.

i should also say that this plane isn't a LRF by any means, at least not now. its faster than my square 5.5 and the safe turning radius is 3-5 times as big (considering the square 5.5 turning radius is about 1 foot). maybe after i get it under control i will try it in smaller spaces, right now its a small gym flier.

I really, really, like this plane, mainly because it is the first plane i have ever built that weighs under a gram and actually flys. now i can go around and tell people i have a plane that weighs under 1 gram. the main problem there is that most people don't know how much a gram actually is, or how heavy the parts are and so on. BUT, other model airplane builders, FF guys, who do know about the gram, but haven't heard about sub gram r/c planes have the best reactions. usually its something like "... no...how? do your have it with you?". breaking preconceived notions about anything is always fun.

This plane uses a stock 3.2mm motor, with about a 1.1" balsa prop. max thrust was measured at 550mg. the prop will end up being redesigned for better performance. eventually. the actuator was wound from 48awg wire. the receiver is a IRXA261 with the updated layout. the battery is the new 10mah from power stream. the wing design is directly copied from Robert's .95g plane, so i own it to thank him for that. the wing was interesting to build, but wasn't a huge pain.

weight breakdown:
airframe + act: 150mg
10mah li-poly: 400mg
IR RX: 120mg (76mg sensor, 44 mg receiver)
stock 3.2mm motor: 270mg
prop: 10mg
glue + wires + misc: 30mg

Total weight: .98g

video: https://www.rcgroups.com/forums/show...76#post7318766

This plane now uses a brushless motor which weighs 180mg, bring the total weight of this plane to 0.89g.
Last edited by Angry_Monk; Mar 16, 2008 at 04:29 PM.
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Apr 15, 2007, 10:21 AM
Registered User
very nice
Apr 15, 2007, 11:01 AM
Droner
SebastianJ's Avatar
Beautiful work Monk! Awesome!!
Lets have a vid please.

Sebastian.
Apr 15, 2007, 11:53 AM
Your ruler, in part...
Angry_Monk's Avatar
Quote:
Originally Posted by bas10an
Beautiful work Monk! Awesome!!
Lets have a vid please.
i'll try to get a vid soon. trouble is its hard to follow the plane and have the image big enough where you actually see this thing fly. right now it doesn't look like a plane flying; its more like a small blur moving around that may or may not be a plane .
Apr 15, 2007, 12:31 PM
Registered User
nice plane !!! congradulations ..
Apr 15, 2007, 01:17 PM
Droner
SebastianJ's Avatar
Monk, what are you using to TX koichi's receiver?
Apr 15, 2007, 03:48 PM
Your ruler, in part...
Angry_Monk's Avatar
Quote:
Originally Posted by bas10an
Monk, what are you using to TX koichi's receiver?
im using his TX circuit mounted is a PS2 controller. i posted about it a while back. here is the link if you are interested.
https://www.rcgroups.com/forums/showthread.php?t=641077
Apr 15, 2007, 04:57 PM
Registered User
Martin SJ's Avatar
Hey Monk,
Beautiful job. Congratulations!!!
I tell people who don't know how much a gram is: take a regular sized Kleenex, tear it in half - that's a little less than a gram.
--Martin
Apr 15, 2007, 07:52 PM
Your ruler, in part...
Angry_Monk's Avatar
thanks everyone, it is a good looking plane.

i think i should have flight vids up next weekend.

Martin - i need to remember that one, that is a good comparison for a gram. i usually tell people the plane weighs less than half of a penny.
Apr 15, 2007, 08:41 PM
Registered User
Hi Brian. VERY good job on your plane . I am very impressed on how clean you built it. I will be waiting for that video . I wish my airframe came out as clean as yours. I do have a question though. How were you able to make that prop the correct pitch for the Shicoh motor?
More questions later!

Regards, Jon
Apr 15, 2007, 09:19 PM
Your ruler, in part...
Angry_Monk's Avatar
Jon,

i found this post a while ago: https://www.rcgroups.com/forums/show...1&postcount=48 and i really liked the way the props were made and looked. i used the laser cutters at my college to cut out the pitch stand (seen in picture # 7) and pitch plates used to angle the blades. depending on the angle pitch plate you use, and the distance from the hub you get a prop of pitch X. there are tables posted my cmartin somewhere else in that thread.

the prop is not perfect, it gets 550mg of thrust on a stock 3.2mm when it really should get around 700-800mg. i will eventually experiment more with different pitch plates to find the best one.
Apr 15, 2007, 09:20 PM
Registered User
rguillot's Avatar
Nice job Monk (furious friar? ):good looking plane, good pics, great effort all around. I'm surprised it's not a LRF(yet). At that wingloading it most likely could be with a little fiddling of the CG and incedence. If it slows down a bit you might regain some rudder control without modifying it. I see the way you used wire insulation for wingpost tubes- good idea!

BTW, .3mm carbon rod splits pretty easily and the D-section bends easier and lends itself to flat tail surfaces. Try it and you'll see...

What's next? WR?

Congratulations,
Robert

Edit: I forgot to say your IR sensor could drop about half it's weight. If you sand off the copper plates till they are paper thin. Soldering becomes like surgery then. My lightest one was 25-30mg. Rx could drop 10mmg too
Last edited by rguillot; Apr 15, 2007 at 10:14 PM.
Apr 15, 2007, 09:35 PM
Registered User
Thanks for the info Brian. I may try that Prop idea, and see how it works. I can see that you used wire insulation for adjusting the incedence like I did. It works pretty well. I was thinking of replacing it with heat shrink tubing instead. That way, all you will have to do is dab it with the soldering iron to tighten it back up when it gets loose.

-Jon
Apr 15, 2007, 10:20 PM
Registered User
rguillot's Avatar
Just noticed one more thing. How doe the act work in still air? snap-snap? The tape hinges look wide. A 1/4 that width would make a much freer hinge perhaps?
Apr 16, 2007, 10:22 AM
Your ruler, in part...
Angry_Monk's Avatar
most of the electronics on this plane were first time builds. RX was the first one i ever built (second one i built was 36mg, saving that for another plane). the sensor was the first one i sanded down that worked. i just wanted to see if i could make a sub gram plane with those weighs. the next one i build i will pull out all the stops and get the parts as light as i can.

i am in the process of redesigning the rudder. i am using the general ideas about putting area ahead of the hinge to help the actuator when deflecting. basically im doing exactly what Jon did on his square 5.5. im starting to think that the IR RX doesnt give fully power to the actuator, because my plantraco RX i used on my square 5.5 could move that rudder around without any problem (and both planes use about the same actuator).

the new rudder will also have smaller hinges. the ones on the rudder now are way too big. the rudder does look proportional when no air is moving over it.

which direction would i have to move the CG in order to get slower flight? backwards?

Jon,
the wire insulation idea is good, i think i heard it from you when you were talking about your 35mg airframe. i think i did try shrink tube instead of insulation, but it ended up being heavier. also, if its on CF rod, and you touch it w/ a soldering iron, the heat may cause the CF to break.


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