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Mar 31, 2018, 07:29 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by bazsound

if yoiu push forward on the right stick, the elavotr shoiuld move up, pull doown the elavtor moves down

Are you sure about that bazsound ?


Maybe an illustration will be easier to understand ↓ :
Last edited by balsa or carbon; Mar 31, 2018 at 09:33 PM.
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Mar 31, 2018, 08:58 PM
Kimbers Keeper.
BHOFM's Avatar
I think we have found the problem??
Mar 31, 2018, 09:08 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by BHOFM
I think we have found the problem??
What's your guess ?
Mar 31, 2018, 10:29 PM
Scratch building addict
rotagen's Avatar
Quote:
Originally Posted by balsa or carbon
rotagen ,

the EzFly really IS a great design , you should build one !

If you take a look at the plans ↓ , you'll see that the KFm wing & h-stab are flat foam and are both on the same horizontal plane ... there is no positive incidence or negative incidence on either one . And the prop is centered vertical in a vertical slot , and centered horizontal in a horizontal slot ..... so there is no downwards thrust angle . But it has some down thrust effect because the motor/prop are mounted slightly ABOVE the pitch axis ( and center of mass ) .
Interesting. I've heard of some sailplane guys using zero incidence as well. In my opinion the reason you are able to get away with it is KF wings (at least in my experience) have much lower lift than a normal airfoiled wing. Less lift = less moment force pushing the nose down.

A zero incidence gives you an advantage in avoiding drag... neat. And still as soon as you nose down the hor stab comes into action.

But make a nice smooth upper surfaced fatter airfoil and I bet anything you would nose down like crazy. Of course you could probably fix that by moving cg back...

Speaking of CG I bet yours is well back of where I normally place mine.

I made a slightly negative incidence plane once after reading something about it on a sailplane site... impossible to fly no matter where you put the cg... weird thing, it flew great until that first turn then all hell breaks loose.

Anyways, what a fun hobby and that thing flies great.

I
Last edited by rotagen; Mar 31, 2018 at 10:36 PM.
Mar 31, 2018, 10:59 PM
Kimbers Keeper.
BHOFM's Avatar
Quote:
Originally Posted by balsa or carbon
What's your guess ?
Up or down? Could be either or?
Apr 01, 2018, 10:24 AM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by balsa or carbon
When I fly tomorrow morning I'll shoot a demo video of hand launching my EzFly .
Sorry , it was too windy and rainy to fly this morning .....
Apr 01, 2018, 11:25 AM
Registered User
E-Challenged's Avatar
Your model has an extremely short nose and looks extremely over weight. That piece of ply wood on the bottom ???. Try flying a proven foamie high wing design and try to copy the dimensions, power system, battery pack setup.
Apr 02, 2018, 03:19 AM
Registered User
Quote:
Originally Posted by balsa or carbon

Are you sure about that bazsound ?


Maybe an illustration will be easier to understand ↓ :
and this is why i avoid posting from my phone as its such an effort to just try and get a legible message the mistakes get missed, and a fatal mistake at that!

ive corrected the original post.
Apr 02, 2018, 12:16 PM
Registered User
So hopefully should be flyin today, going to fix the motor mount.
Apr 02, 2018, 12:36 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by jawsqb
So hopefully should be flyin today, going to fix the motor mount.
Can you post some photos of your finished EzFly ?

If possible , shoot a video so we can help you with potential launching/flying problems .
Apr 03, 2018, 09:04 PM
Registered User
Quote:
Originally Posted by balsa or carbon
1 ) OK , the polyhedral is a very important part of the EzFly design ...... that's what gives it stability . It would have been easier to add the polyhedral to the wing BEFORE you installed it onto the plane .
400g is not unreasonable . The heavier it is ( relative to the wing area ) , the faster it is forced to fly . The lighter it is ( relative to wing area ) , the slower it is able to fly .

2 ) The spot on top of the fuselage ( where the motor/prop goes ) is designed for a 10mm stick mount , but you'll just have to improvise a way to mount your motor so the PROP is straight and centered in the vertical & horizontal prop slots . The two forces on a motor mount are : thrust ( pushing forward ) and torque ( twisting OPPOSITE of motor rotation ) . So mount the motor in a way that it won't come loose from thrust or torque .

3 ) At the wing tips , the starting CG is about 1/4" to 1/2" in front of the KFm step . Then adjust the CG ( in small increments ) forward or rearward for optimum flight . I mount the batteries on velcro right on top of the nose , leaving room to move the battery forward/rearward as needed . For the slowest flight , move the battery rearward until the plane flies just shy of porpoising at half-throttle .

4 ) A triblade prop will be fine if it's appropriate for your motor/voltage and fits in the prop slots .
Quote:
Originally Posted by balsa or carbon
Did you follow these instructions from post #49 ? :
" find an area with the thickest grass cushion and no wind , then with the rudder & elevator centered and the throttle at 1/4 to 1/3 , throw the plane STRAIGHT AHEAD , making sure the wings are level when the plane is released from your hand . Then RESIST the temptation to move the rudder or elevator , and observe what it does as itís heading gradually towards the ground . If it pulls to the right , adjust the rudder trim a little to the left . If it noses down SHARPLY , move the battery rearward a little bit , etc .

Once itís going fairly straight , then increase the throttle to 1/2 to 3/4 and throw it straight ahead with the wings level .... it should then gently climb . Again , resist moving the rudder or elevator until it has a little altitude .... then make a GENTLE turn with as little banking as possible ."

And I think I forgot to mention : start with low rates on your rudder & elevator . Do you know how to set up low/high rates on your FlySky transmitter ?

The hand launch throw needs to be hard enough to get past the stall speed , but not so hard that the nose pitches up a LOT . Getting the hand launch throw right is just another one of those things that takes practice .

If you get a video of your next flight attempt , I can analyze it to see what you're doing right or wrong . Don't worry about beginner issues , EVERYONE OF US here on RC Groups was a beginner at one time ..... and I guarantee you I've crashed WAY more planes than you have .

Here's one ( or two ) of my crashes on video :



https://www.youtube.com/watch?v=d3WlhjgxOpE


So here's my plane as of yet.

Still no success in flight . Sorry wasn't able to get video this time either, I definetely will next time.

The behavior I'm getting is:

- Plane preety much nose dives as soon as thrown
- When holding the plane and increasing throttle, the plane feels like its trying to curve downwards.


I marked where I was measuring CG on the picture.

Let me know your thoughts! Feeling pretty discouraged, all my planes thus far have been failures.
Apr 03, 2018, 10:22 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by jawsqb
So here's my plane as of yet.

Still no success in flight . Sorry wasn't able to get video this time either, I definetely will next time.

The behavior I'm getting is:

- Plane preety much nose dives as soon as thrown
- When holding the plane and increasing throttle, the plane feels like its trying to curve downwards.


I marked where I was measuring CG on the picture.

Let me know your thoughts! Feeling pretty discouraged, all my planes thus far have been failures.
In your photo you have a lot of down elevator , but the pushrod does not appear to be connected to the servo . If the elevator is in that position when you hand-launch it ...... it will definitely nose dive . Can you post several photos ( from different vantage points ) showing what your plane looks like "ready for flight" ...... with the transmitter on and the battery connected ?

Yes , increased ( full ) throttle pushes the nose down ( down thrust effect ) due to the motor/prop being mounted above the pitch axis & center of mass . As I said in the "first flight" instructions : with the rudder & elevator centered/neutral , try the first hand-launch at 1/4 to 1/3 throttle to observe the plane's tendencies .

A video will really help me see what's going on . Don't get discouraged ..... we'll get you flyin' !
Apr 04, 2018, 03:14 AM
Registered User
If your plane is nose diving and your control surfaces are all neutral then that could mean it is nose heavy, however we do no know how you are launching it because improper launch could cause it to nose dive. launch it at just a slight angle up, not too steep at an angle because launching at a high angle will cause the plane to slow down at which point the nose will drop.

if everything is right and the balance is right, it should glide slightly nose down as long as theres enough airspeed.

Also what is with the balsa spars? is that part of the plan? If its not it will be adding considerable weight to the plane.

right gonna get ink for my printer and build this plane

https://www.youtube.com/watch?time_c...&v=cEJvRPPU7fo
Last edited by bazsound; Apr 04, 2018 at 03:46 AM.
Apr 04, 2018, 12:52 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
If possible , also post a photo of your EzFly with :
transmitter on & battery plugged in , while balanced level on something ( two chair backs or two pencil erasers ? ) at the CG marks .
Apr 04, 2018, 07:03 PM
Kimbers Keeper.
BHOFM's Avatar
B&C, You talk about the EZflier so much, I have to build one! I am holding you personally responsible for this project, including all costs incurred during the build. Including and not
limited to cost of material, cost of electronics, cost of maintaining the place of the build,
including heat and or air conditioning, water, cost of laundry of work cloths, cost of cleaning
work place. You will not be held responsible for food and beverage during the build, but wil
be billed for the cost of TV cable watched during the build. You will be billed for cost of printing
the plans and the tape and blade used in putting the plans together.

I will bill you upon completion of the project!





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