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  #46  
Old 08-11-2006, 11:42 AM
Wayne Hicks Wayne Hicks is offline
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What's the question again? (I forget.) If it has something to do with landing gear geometry, it's really very simple.

To reduce rotation speed (get off the runway quicker), do these things:

(1) Locate the PLANE's cg when loaded to be as near to the main gear axles as possible. The more the CG is over the main gear, the less weight there will be up front, the less weight the canard will have to lift. HOWEVER, how far aft you can move the cg is LIMITED by aerodynamics -- the major limitation being deep stalling the main wings. For the plans-built Cozy MkIV, the aft cg limit is 102.5 (or something like that). That position is about 6 inches ahead of the FS position of the main axles. HOWEVER part deux, most of us can't fly aft cg except solo and lightly loaded. I'm pretty certain the Cozy 540RG is stretched to offset the weight of the heavier engine and landing gear set-up. Not to get off the ground quicker.

(2) Build the plane so that the canard has a more positive angle of attack on the take-off roll.

(2a) First option (my opinion) is to leave the nose strut longer than called for in the plans. Mine nose strut is one inch longer than per plans. That's about as long as you can go. My nose wheel barely clears the instrument panel when it is retracted into the wheel well.

(2b) Second option (again, my opinion), is to mount the canard into the fuselage with a higher angle of attack. Right now, the plans call for the canard to be at a zero incidence angle when the fuselage is level. You use the G-template to set that angle. Nat changed the G-template to provide for a more positive incidence angle, about 1-2 degrees if I recall correctly. The goal of doing this is to offset the nose going down when loaded. With the front seats loaded, the nose spring is compressed, and the nose points a little lower than when NOT loaded. Thus, the canard also sits at a lower incidence angle on takeoff. So the goal of setting the canard to a higher incidence angle is to offset the nose-low condition and return the canard to a neutral or positive incidence angle on take-off. HOWEVER, the more positive the incidence angle in flight, the higher the canard wing stall speed will be. The faster your landing approach speeds will be. How much higher? I dunno, A few knots perhaps.

(2c) Third option is to lower the arse end by moving the main wheel axles up a bit on the gear legs. An inch higher would makes a significant impact. HOWEVER, did I just say impact? The lower the back end, the higher the chaces of prop strike on rotation, more likely over-rotation. Those of us flying 3-bladed props can accommodate this change better then those with 2-bladed props. 3-blade props tend to have less a prop diameter than 2-bladed props, and hence provide more ground clearance.

(2d) Leave the canard wing at the original length. HOWEVER, Nat has proven that you can only load the plane to an aft CG of 100 point something! That's why he shortened the canard wing length, to regain some aft CG to 102.5 (That, and he added the lower winglets, which are good for about 0.5 inches of aft CG.)

(3) If you want the plane to remain level when parked unattended, then you must make compromises to that presented above. As I mentioned in an earlier post, the weight on the nose gear goes up significantly as the nose is lowered. Lowering the nose about 2 feet is all it takes to reduce the risk of tip-over.

That's all I can think of right now. My brain hurts.
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  #47  
Old 08-11-2006, 11:50 AM
Wayne Hicks Wayne Hicks is offline
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"how does this scare the heck outa you, moving the gear back 2 inches so the plane has better ground sitting ability. give up a little forward CG."

-----> Dust, let me tell you this for the LAST TIME. Moving the axle location doesn't affect the PLANE'S cg. You don't loose forward cg! It only affects the weight distribution on the wheels.

Repeat after me:

The more weight on the nose gear....
(the more weight on the nose gear....)

The harder the canard has to work to lift the nose...
(the harder the canard has to work to lift the nose....)

The higher the airpseed you need to produce that lift...
(the higher the airspeed you need to produce that lift...)

The longer the takeoff roll needed to accelerate to that speed.
(the longer the takeoff roll needed to accelerate to that speed.)

Don't make me stick you in the corner of the room for time out.
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  #48  
Old 08-11-2006, 11:56 AM
Wayne Hicks Wayne Hicks is offline
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Nat's rudders are 3 inches longer because he didn't have lower winglets originally. Look at the plans and you can see that the part of the rudder comes from the lower winglet.

That's the ONLY reason he extended them, to regain the surface area lost by not incorporating the lower winglets. It wasn't to gain more rudder authority.

I did the same thing because I originall was going to be sans lower winglets, too. Heck, I wish I would have cut my rudders full span. But that's another thread altogether.
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  #49  
Old 08-11-2006, 12:19 PM
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Dennis Passey Dennis Passey is offline
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Just to respond. "Scares the he!! out of me" is really, Dust, just a way of saying based on what you had described based on the gear location and etc as Wayne pointed out- I picture you augering into the treeline on takeoff somewhere trying to lift that bird on a high elev strip on a 85+ degree day.
I recall a great flight at full fuel with 4 large men in Marcs cozy and it performed beautifully in the heat of Tehachepi- and that doesnt seem possible in the bird you are describing as a good build..thats all. The axle location relative to rotation and the canard incidence is...blah, blah, blah...in less than optimal ....blah, blah.
You know the story. Why the .....Im outta here.
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  #50  
Old 08-11-2006, 12:26 PM
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Quote:
Originally Posted by Wayne Hicks
-----> Dust, let me tell you this for the LAST TIME. Moving the axle location doesn't affect the PLANE'S cg. You don't loose forward cg! It only affects the weight distribution on the wheels.
heh heh heh

if a = b and b = c then a = c

if moving axles back limits the take off ability in forward CG then??

Quote:
(3) If you want the plane to remain level when parked unattended, then you must make compromises to that presented above. As I mentioned in an earlier post, the weight on the nose gear goes up significantly as the nose is lowered. Lowering the nose about 2 feet is all it takes to reduce the risk of tip-over.
just one of those you gotta know or remember, I just don't like those kinda things. I have seen a KR2 that went forward while an A&P was working on HIS plane while it was running, not a pretty sight, trashed engine and prop, while he tried to run to the back of the plane to hold the tail down.

his tail was then between his legs
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  #51  
Old 08-11-2006, 01:01 PM
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So many essays I start writing I know would be a waste of time. Heck with it. Dust, perhaps you're not really, really, expecting yourself to fly your Cozy, but only manufacturing something (b)leeding-edge to sell? Sounds like you're making every excuse to delay you and the Cozy of being capable of flying. If you can't fly or can only obtain marginal piloting skills there's nothing you can do the Cozy to make up for it. Some of your mods will only trade a need for special operating considerations and techniques from 'here' to 'over there'.
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  #52  
Old 08-11-2006, 01:19 PM
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The plane will fly and fly well. Starting a week from sunday, i will work on it monday, thurs and friday night and saturday and sunday.

Monday night will still be woodworking, tues will still be beers with vtail nic.

I will never sell it.

Most of what i am talking about i am too far progressed to do, will not change gear position, front or back.

I will fair everything that i can and recess every screw and hinge

i will redo every little item that i wish to, i no longer have partners to offend with my pickiness.
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  #53  
Old 08-11-2006, 07:13 PM
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Quote:
Originally Posted by Wayne Hicks
(2b) Second option (again, my opinion), is to mount the canard into the fuselage with a higher angle of attack. That's all I can think of right now. My brain hurts.
I was planning to adjust, if needed, the angle of the canard based on the amount of elevator defection, up or down, based on how my plane flies after it ..... well flies.

For my plane, i am not worried about take off distance because of the planned CS prop.

better go and practice my flute now
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  #54  
Old 08-11-2006, 09:20 PM
DouglasHolub DouglasHolub is offline
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Make sure shifting the main gear back doesn't put too much weight on the nose gear. There's a lot more weight on a fully loaded FG Velocity's nose wheel (500 lbs) than there is on a fully loaded Cozy Mark IV (223 lbs).

I'm putting a Wilhelmson electric nose lift on my FG Velocity, so Jack tried putting a stiffer spring in it since it was going into a Velocity. I'm in the process of installing it now, so I'm not even sure it will work, yet.

Actually, I do hear of Velocities tipping over every now and then if they are not tied down and a gust of wind comes along.

Speaking of the Wilhelmson electric nose lift, I was not very happy with the control panel that came with it. The colors and sequences of lights are not very intuitive. There is a toggle switch that goes up and down and two lights, upper and lower. Each light can be one of two colors. (There is also a second toggle switch for the "lock" position that keeps the motors from moving when they are not powered up.) When you move the toggle switch up, the gear goes up and the lower red light comes on steady. When the gear reaches the top limit, the lower red light goes off and the upper yellow light comes on. When you move the toggle switch down, the upper green light comes on steady. When the gear reaches its lower limit, the upper green light goes off and the lower green light comes on. Maybe it's just me, but it's hard for me to remember what lights are supposed to be what color when, and I don't ever want a red light coming on my panel when there is nothing wrong.

So I designed a new circuit. The same two lights, but only two colors. The top one is yellow and the bottom one is green. When the toggle switch goes up, the upper light flashes yellow. When the gear reaches the top, the flashing yellow becomes steady yellow. When the toggle is switched down, the lower green light starts flashing. When the gear reaches its lower limit, the green light is steady.

And my control panel only has one toggle switch. The middle position of the three-position toggle switch is the "lock" position.
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  #55  
Old 08-11-2006, 09:25 PM
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the two switches are crapola also - replaced em - did you replace yours?

Also replaced the 9 pin connector - the one it came with was rated at 10 cycles, take aparts and put togethers
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  #56  
Old 08-11-2006, 09:42 PM
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MarbleTurtle MarbleTurtle is offline
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Dust... I think I'm gonna side with the peanut gallery on this one buddy.

As I often say in my line of work... "that ain't a defect, that's a FEATURE!" Keeping the mains near the CofG has all the benefits discussed. The nose gear is a match stick. Moving the mains back from the CofG puts more load on the nose gear and wheel than I think it can handle.

But I wouldn't even if I thought the nose gear COULD handle the extra load. One thing I don't like about the Velocity is the large canard. It's basically a bi-plane (or maybe a mono-and-a-half plane?). Ideally, you want one flying surface creating lift. Lift creates drag, a large part in the form of tip vortices. Since nature is a vacume whore, those tornadoes at the wing tips rob you blind. Outside of structural considerations, monoplanes are more efficient than bi-planes. You want one wing doing most of the work, and make everything else streamlined... ideally.

However we DO have a wing up front. And a nose gear. Well... think of it as tipping a chair on two legs and then leaning it lightly against a wall. Much more stable than trying to balance on only two legs, but the wall is lightly loaded. Move the legs of the chair further away from the wall and the wall is more loaded... or dented.

So... you add load to the nose gear (higher lift requirement at takeoff, but no add in gross weight) so you now you start looking at making the canard larger. Now you get a bigger airfoil out front creating more drag... all so your bird doesn't moon the other "normal" planes while parked. Bad idea.

Don't get me wrong... I still like the Velocities. I just think they would fly faster if they didn't need such a big canard.

We should continue to kick around any and all ideas around here. I just think this idea is headed for the trash. Sorry.
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  #57  
Old 08-11-2006, 09:52 PM
DouglasHolub DouglasHolub is offline
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I'm not using his toggle switches, either. In fact, I'm sending the whole harness back to him. He offered to refund the harness cost, which I thought was very decent of him. I think Jack is probably a mechanical engineer and farmed out the wiring harness. I'm very impressed with the quality of the mechanicals, though. And Jack was very helpful making engineering changes and working with me to try to get his nose lift to work in a Velocity.

I actually like the 9-pin connector, but I didn't know it was spec'd for only 10 connection cycles. I guess I'll try to route the harness somewhere that it won't need to be connected and unconnected often.
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  #58  
Old 08-11-2006, 11:10 PM
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Quote:
Originally Posted by MarbleTurtle
But I wouldn't even if I thought the nose gear COULD handle the extra load. One thing I don't like about the Velocity is the large canard. It's basically a bi-plane (or maybe a mono-and-a-half plane?). Ideally, you want one flying surface creating lift. Lift creates drag, a large part in the form of tip vortices. Since nature is a vacume whore, those tornadoes at the wing tips rob you blind. Outside of structural considerations, monoplanes are more efficient than bi-planes. You want one wing doing most of the work, and make everything else streamlined... ideally.

Don't get me wrong... I still like the Velocities. I just think they would fly faster if they didn't need such a big canard.
Heh. That's funny, it's one of the I really like about the Velo, looks better proportioned to me. Everything's a trade-off, though. At least it keeps it from tipping over. And picks my heavy butt off of the ground.

Brett
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  #59  
Old 08-12-2006, 12:49 AM
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YES - the mechanicals are very good and appear robust.

interesting how no one has done a calculation on how much extra weight would be added to the nose gear and are sure it is too much.

Talk to a non canard person and see if they easily accept the tipsy nature, i think we have just accepted it.
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  #60  
Old 08-12-2006, 01:27 AM
Lynn Erickson Lynn Erickson is offline
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Keeping up on this thread is like work. my head hurts. just a few thoughts on the subject. landing gear thingys wasn't it?

If building a cozy, stick to the plans gear they work great! flew one today and it worked!

The electric nose lift is a good mod and makes the plane much easier to handle almost a must on the Mark IV.

Oleo struts are not needed. really! they are not needed on these planes. if you just want them, well then you just want them. But, you don't need them. just repaired one on a Glassair today, alot of work no real gain.

Stearable nose wheel, to you guys I will say, fly in a canard first before you go to all that trouble and add all that weight.

As for the Retract Guys and Gals they know what they are getting into or they don't. they do know the risk they are getting into and have made the choice to go that way anyway because they are the cool thing to have and fun to operate. it is fun to fly a retract. there is some speed gain, although not much , for some it is a gain, none the less.

Now, as for moving the mains back. It has been done mostly with no change to performance. you can ask me how I know what moving it 4" back will do.

first of all, they say if you move the mains back a few inches the nose will not lift as soon. who cares when the nose lifts. its when the whole planes flys that counts. the runway will end at some point. the plane lifts when both the canard and wing are up to flying speed. rotating the nose up before the main wing is ready to fly does not shorten the takeoff roll.

the CG does not change if you move the mains back. I think that has allready been said by a famous pilot or some one anyway. I do know it has been told to someone though.

Getting the plane up to the take off speed is what uses up most of the runway used by a canard. simple fix. more HP and less weight.
The higher takeoff speed required by our type canard aircraft uses some runway. easy fix, get a different type of plane
wing loading uses runway, the heavier the load on the wings the more speed needed to lift off. fix, don't put all those un-needed things ( you think you need ) in the plane or get a bigger and more powerful plane.

And if you don't what to fly a bi plane or a canard because they have two wings and there is to much drag. well a flying wing might be for you, only one wing, less drag .

Just a few thoughts on, what was the subject anyway?
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