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Cox Engine of The Month
Li'l Wizard Stunt
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Li'l Wizard Stunt
I knocked out the buildup of my son's Li'l Wizard. I chopped about 3/4" of the nose and added some extra trailing edge. I didn't want him to get bored so hopefully he can do a few stunts with it.
Now that I knocked off the nose some how do I go about figuring out where the CG is?
https://i.imgur.com/SyjBy.jpg
https://i.imgur.com/5oobX.jpg
Now that I knocked off the nose some how do I go about figuring out where the CG is?
https://i.imgur.com/SyjBy.jpg
https://i.imgur.com/5oobX.jpg
Cribbs74- Moderator
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Posts : 11907
Join date : 2011-10-24
Age : 50
Location : Tuttle, OK
Re: Li'l Wizard Stunt
Grab the engine and fasten it on with a pushpin. Find the balance point in this configuration and mark it. If it is at 20% of the wing area is in front of the CG then you should be OK. If it is much further back you are tail heavy. Naturally you will need to fly and trim, but it shouldn't be too far off.
Shortening the nose of the lil Wizard is all it should have taken to make it come alive for stunt.
Phil
Shortening the nose of the lil Wizard is all it should have taken to make it come alive for stunt.
Phil
pkrankow- Top Poster
- Posts : 3025
Join date : 2012-10-02
Location : Ohio
Re: Li'l Wizard Stunt
Thanks Phil,
Yeah, I remembered the nose needed to be shortened, but I figured a little more wing area couldn't hurt. I will mount the motor and check where she balances at.
Yeah, I remembered the nose needed to be shortened, but I figured a little more wing area couldn't hurt. I will mount the motor and check where she balances at.
Cribbs74- Moderator
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Posts : 11907
Join date : 2011-10-24
Age : 50
Location : Tuttle, OK
Re: Li'l Wizard Stunt
From my bad experiences with maidening unknown models, all I can add is to only use a SIP of fuel. You can probably hang on for 2 or 3 laps and then you'll know which way to go with the CG. If it's too easy to fly(nose heavy) or too unstable(tail heavy), adjust accordingly until it's right on the edge of twitchy. That's your max stunt setting.
_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
RknRusty- Rest In Peace
- Posts : 10869
Join date : 2011-08-10
Age : 68
Location : South Carolina, USA
Re: Li'l Wizard Stunt
[quote="RknRusty"]From my bad experiences with maidening unknown models, all I can add is to only use a SIP of fuel. You can probably hang on for 2 or 3 laps and then you'll know which way to go with the CG. If it's too easy to fly(nose heavy) or too unstable(tail heavy), adjust accordingly until it's right on the edge of twitchy. That's your max stunt setting.[/quote
Looks like that's what I am gonna have to do Rusty.
Here it is, almost done.
https://i.imgur.com/4jo5VUo.jpg
Looks like that's what I am gonna have to do Rusty.
Here it is, almost done.
https://i.imgur.com/4jo5VUo.jpg
Cribbs74- Moderator
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Posts : 11907
Join date : 2011-10-24
Age : 50
Location : Tuttle, OK
Re: Li'l Wizard Stunt
My son will be building a Brodak Lil Wizard soon, kit should arrive today.
By comparing your photos with the Brodak Lil' Wizard it looks like your nose is 3" shorter at least. You only removed 3/4" ?
I hear these are very nose heavy and I'd love to make the plane more maneuverable.
This may be a very novice question but... how does one move the CG forward or backward? Adding weight to the fuselage?
Thank you. Greg
By comparing your photos with the Brodak Lil' Wizard it looks like your nose is 3" shorter at least. You only removed 3/4" ?
I hear these are very nose heavy and I'd love to make the plane more maneuverable.
This may be a very novice question but... how does one move the CG forward or backward? Adding weight to the fuselage?
Thank you. Greg
Sig Skyray- Gold Member
- Posts : 222
Join date : 2015-04-02
Age : 63
Location : Lake Mary, FL
Re: Li'l Wizard Stunt
I love the new look Wizard Ron. The increased wing area makes it. Looks like the trailing edge has a little "up" in it or does it flow with the plane of the wing? Are those wing skids functional? Whats the finish? Too many questions?
Bob
Bob
rsv1cox- Top Poster
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Posts : 11250
Join date : 2014-08-18
Location : West Virginia
Re: Li'l Wizard Stunt
Sig Skyray wrote:My son will be building a Brodak Lil Wizard soon, kit should arrive today.
By comparing your photos with the Brodak Lil' Wizard it looks like your nose is 3" shorter at least. You only removed 3/4" ?
I hear these are very nose heavy and I'd love to make the plane more maneuverable.
This may be a very novice question but... how does one move the CG forward or backward? Adding weight to the fuselage?
Thank you. Greg
Greg,
This was built from an original kit and was designed around a Babe Bee engine. As you can see the Brodak version was designed for a beam mount using a front rotary engine. Generally the TD's and Brodak .049's are lighter so they require a longer nose to balance.
To answer your second question there are many ways to shift the CG and adding weight is usually the last thing you would want to do.
Normally you would either cut the nose, move the wing location, shorten the tail or find an engine that weighs more or less. Doing these things will shift the CG front or back.
Ron
Cribbs74- Moderator
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Posts : 11907
Join date : 2011-10-24
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Re: Li'l Wizard Stunt
rsv1cox wrote:I love the new look Wizard Ron. The increased wing area makes it. Looks like the trailing edge has a little "up" in it or does it flow with the plane of the wing? Are those wing skids functional? Whats the finish? Too many questions?
Bob
Bob,
The wing has an airfoil sanded into it from the factory so it makes it appear that the TE points up. It's actually level with the bottom of the wing which is flat.
The little tips are not actually skids and have no function. They are ply if I recall correctly and were added for decoration I assume. They inboard one acts as a leadout guide.
Paint is Krylon with TF clear over it. Not my best work, but it's a trainer so....
Cribbs74- Moderator
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Posts : 11907
Join date : 2011-10-24
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Re: Li'l Wizard Stunt
That's my combo of choice too Ron. Did you use a primer or sanding sealer?
rsv1cox- Top Poster
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Posts : 11250
Join date : 2014-08-18
Location : West Virginia
Re: Li'l Wizard Stunt
Ron,
Cool plane. I like the idea of making it more versatile. My first plane was a Lil' Wizard with a black widow and I outgrew it fast.
To locate the proper c.g. Point you want 20% of the average chord. Since you have constant taper from root to tip the average chord will be the halfway point of one of the wing panels. Measure the chord at that halfway point and calculate 20% of that length. Go back that far from the leading edge and that is where you want your c.g.
Jim
Cool plane. I like the idea of making it more versatile. My first plane was a Lil' Wizard with a black widow and I outgrew it fast.
To locate the proper c.g. Point you want 20% of the average chord. Since you have constant taper from root to tip the average chord will be the halfway point of one of the wing panels. Measure the chord at that halfway point and calculate 20% of that length. Go back that far from the leading edge and that is where you want your c.g.
Jim
JPvelo- Diamond Member
- Posts : 1972
Join date : 2011-12-02
Age : 57
Location : Colorado
Re: Li'l Wizard Stunt
Paint almost always moves the CG towards the back, simply because there is more area to paint behind the CG due to the heavy engine.
Rattle can paint is heavier than dope, so if you choose that route be careful and try to stay with 1 coat after a well-sanded series if primer coats.
Phil
Rattle can paint is heavier than dope, so if you choose that route be careful and try to stay with 1 coat after a well-sanded series if primer coats.
Phil
pkrankow- Top Poster
- Posts : 3025
Join date : 2012-10-02
Location : Ohio
Re: Li'l Wizard Stunt
Funny, I am getting more tips and kudos now than when I posted this over a year ago.
It's been finished, flown, crashed, flown many times since then. I only flew it once just to check it out then passed the handle to my son. If I were to do it over again I would probably have done it without the wing extensions.
It's been finished, flown, crashed, flown many times since then. I only flew it once just to check it out then passed the handle to my son. If I were to do it over again I would probably have done it without the wing extensions.
Cribbs74- Moderator
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Posts : 11907
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Re: Li'l Wizard Stunt
Our kit came today and I'm glad you mentioned not adding in the wing extensions Ron because just before reading that I decided it was a good idea. I found ample balsa here in another box and was ready to go for it. I will be shortening the nose. Thanks for the update.Cribbs74 wrote:Funny, I am getting more tips and kudos now than when I posted this over a year ago.
It's been finished, flown, crashed, flown many times since then. I only flew it once just to check it out then passed the handle to my son. If I were to do it over again I would probably have done it without the wing extensions.
BTW, my Carl Goldberg Lil' Wizard kit from the 70's used a lead rod for outboard wing weight. That bar was about 1/8" by 3" long, no kidding... it was big. This kit says to glue two pennies to the underside of the outboard wing tip. Very curious to see how this will model will compare.
Greg
Sig Skyray- Gold Member
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Re: Li'l Wizard Stunt
Greg,
It's really up to you, It's just it didn't help anything. I think Phil was right about that point.
The Brodak Wiz, a Medallion and a properly plumbed hard tank would make an excellent trainer.
Please post pictures of your progess.
Ron
It's really up to you, It's just it didn't help anything. I think Phil was right about that point.
The Brodak Wiz, a Medallion and a properly plumbed hard tank would make an excellent trainer.
Please post pictures of your progess.
Ron
Cribbs74- Moderator
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Posts : 11907
Join date : 2011-10-24
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Re: Li'l Wizard Stunt
I should add this: If you aren't sure if it's just a little bit nose heavy, when it shuts off flying level, add no input, just hold neutral. If it immediately sinks, requiring UP input, then lighten the nose some more. Of course if it went up at shutoff, requiring DOWN input. your plane is _____________RknRusty wrote:From my bad experiences with maidening unknown models, all I can add is to only use a SIP of fuel. You can probably hang on for 2 or 3 laps and then you'll know which way to go with the CG. If it's too easy to fly(nose heavy) or too unstable(tail heavy), adjust accordingly until it's right on the edge of twitchy. That's your max stunt setting.
Fill in the blank.
Rusty
_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
...and never Ever think about how good you are at something...
while you're doing it!
My Hot Rock & Blues Playlist
RknRusty- Rest In Peace
- Posts : 10869
Join date : 2011-08-10
Age : 68
Location : South Carolina, USA
Re: Li'l Wizard Stunt
RknRusty wrote:I should add this: If you aren't sure if it's just a little bit nose heavy, when it shuts off flying level, add no input, just hold neutral. If it immediately sinks, requiring UP input, then lighten the nose some more. Of course if it went up at shutoff, requiring DOWN input. your plane is _____________RknRusty wrote:From my bad experiences with maidening unknown models, all I can add is to only use a SIP of fuel. You can probably hang on for 2 or 3 laps and then you'll know which way to go with the CG. If it's too easy to fly(nose heavy) or too unstable(tail heavy), adjust accordingly until it's right on the edge of twitchy. That's your max stunt setting.
Fill in the blank.
Rusty
Nose heavy fly poorly, tail heavy fly once?
Phil
pkrankow- Top Poster
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Location : Ohio
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