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  #1  
Old 05-24-2007, 08:05 PM
Northman Northman is offline
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Default Fixed Nose Gear on Long EZ?

I really feel like a complete noob asking this, but I poked around quite a bit and never saw this specific question anywhere.

I'm aware of the CG issues inherent in the Long-EZ design, but is it possible to make a (theoretically) safe modification to allow for a steerable fixed nose gear? Honestly, if I wanted retracts, I'd go full retract. I love the Long-EZ's design, but the hybrid approach to the landing gear really bothers me.

Given a long nose design and 50 pounds of ballast (for sake of argument) can a fixed nose gear be realistically done?

An alternate idea that I was kicking arouind -- a steerable nose gear system, but with a pinned lower shaft that can be removed -- the nose is kept dropped, but when you fly it, you lift it, install the nose gear (and retaining pin -- Clevis, maybe?) and off you go.
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Old 05-24-2007, 08:18 PM
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With that much weight in front of the canard you will overload that wing and cause it to stall. To remove the retractable nose would be akin to trying to order a Cadillac with a manual transmission.
Not good!
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  #3  
Old 05-24-2007, 09:06 PM
Lynn Erickson Lynn Erickson is offline
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Quote:
Originally Posted by Northman View Post
I really feel like a complete noob asking this, but I poked around quite a bit and never saw this specific question anywhere.

I'm aware of the CG issues inherent in the Long-EZ design, but is it possible to make a (theoretically) safe modification to allow for a steerable fixed nose gear? Honestly, if I wanted retracts, I'd go full retract. I love the Long-EZ's design, but the hybrid approach to the landing gear really bothers me.

Given a long nose design and 50 pounds of ballast (for sake of argument) can a fixed nose gear be realistically done?

An alternate idea that I was kicking arouind -- a steerable nose gear system, but with a pinned lower shaft that can be removed -- the nose is kept dropped, but when you fly it, you lift it, install the nose gear (and retaining pin -- Clevis, maybe?) and off you go.
It could be done. you can fly a long eze all day without raising the nose gear. the plane flys just fine, a little slower but there is no wheel pant to help in drag. the nose strut is a bit long to have down the whole time. the problem is it has to retract to store the plane, nose down. so that being the case why not retract it during flight and leave the ugly wheel pant at home.
as for the streerable nose wheel I have to say WHY? what the h#ll for? I will ask, have you flown or flown in a long or cozy? with over 600 hours and 500 landings and takeoffs in ezes I have yet to need a steerable nose wheel and I am sure most other owners will agree.

as for the removable nose gear, how will that look on the flight line when you have to remove the gear and everyone else just pushes a button and the nose is lowered. look mom no hands. the electric nose lift works great in a long eze as well as a cozy. you won't have to worry about 007 stealing your long eze. he will go for the one with the push button lift and off you go.
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  #4  
Old 05-24-2007, 09:19 PM
Nathan Gifford Nathan Gifford is offline
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I believe there was on EZ derivative with a steerable nose gear. It was a special, purpose-built, EZ allegedly built to test some military gear. Presently I think it is in Texas somewhere.

To get this thread off right, what are seeking to do? Is you purpose to have a steerible nosewheel, or an aircraft that does not kneel?

If it to avoid kneeling, there are issues in adding weight to the nose. For one thing you need to have enough weight such that it will not tip over on its rear. You may find that 50 pounds may not be enough. After all you would not want to have a gust tip your plane on its rear.

On the steerable nosewheel, this comes up infrequently. You will find a lot of debate over whether steerable nosewheel or castoring would be better. Both have their own advantages. Probably if you search on steerable you will find much.

The problem with the steerable nosewheel is all the additional hardware it requires. Assuming you go with an oleo strut, shimmy dampers, etc. you might have your 50# already. You also will probably lose some of the aircraft's turning radius.

Another issue are the differential rudders. Velocities have steerable nosewheels and no differential rudders. Without differential rudders you cannot use the EZ/Cozy trick of deploying both rudders at the same time as a speed brake. Of course, Velos fly just fine without differential rudders.

So articulate a few paragraphs about what you are seeking to do and lets this thread evolve.
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  #5  
Old 05-24-2007, 09:40 PM
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Quote:
a steerable fixed nose gear?
You present two problems, Fixed, and Steerable.

FIXED NOSE GEAR:

As you know, the plane is normally parked on its nose because when the pilot is no longer in the seat, the CG is shifted so far aft, that the plane will easily tip over back-wards.

If you desire to leave the plane parked on all three, then the only way to correct for this is to either mount the rear wheels a couple inches farther back, or add weight in the nose.


By doing either one of these, you present problems when the pilot gets in and wants to take off. ON a conventional aircraft the tail (elevators) pushes down. On a LongEZ, the canard lifts, approximately 20% of the weight of the entire plane. By moving the main wheels back, OR adding a significant amount of weight into the nose, This significantly increases the weight that the canard must lift in order to become airborne.

In order to get the canard to lift the additional weight (compared to the original), you either need to increase the speed of the air flowing over the airfoil, OR, increase the angle of attack of the airfoil.

Here is where the problem lies on takeoff roll: Your not going to be able to get the canard to increase its angle of attack, until it can provide enough lift to overcome the new additional weight. So, the only way to get the additional lift, is to increase the speed. (unstick speed)


The bottom line is; YES, you could do this , but you will need to increase your takeoff and landing speeds, substantially.

Keep in mind that the possibility of tipping the plane back on its tail would still exist, it would just be a little more difficult.

IMHO - This modification should not be performed, as the small improvement gained in safe gear operation comes at a decreased safety margin during the takeoff and landing phase of flight.

ALSO: I don't have any test data to prove it, but I don't believe the level of "tip back proof" would even come close to the tried and proven method of "parking on its nose".



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  #6  
Old 05-24-2007, 09:56 PM
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STEERABLE NOSE:

There are a couple of problems with this.

1) Steering linkages, etc add complexity to the design. These become even more complicated if you wish to retract the nose.

2) Because of the geometry of the landing gear, (the mains close together and far from the nose), nose wheel steering inputs will need to be used with caution, as aircraft could easily be tipped sideways.

This wouldn't be a problem if the mains were farther apart (wide track).

The advantage of differential braking (steering) is, its impossible to tip the plane over sideways. If you press to hard to get a sharp turn, the tire starts skidding (or even lifts off the pavement) When this happens, the plane no longer turns. self correcting steering.

IMHO: I would not recommend this modification. Steerable nose on a LongEZ adds complexity, and increases risk of ground handling accidents from ground loops.

Personally, I prefer differential steering on small aircraft. After you taxi around a couple minutes, you'll realize that you can easily out steer and out maneuver any nose wheel steered aircraft.

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Last edited by Waiter : 05-24-2007 at 10:05 PM. Reason: Brain Damage
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  #7  
Old 05-24-2007, 11:56 PM
Northman Northman is offline
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Waiter, et al.

Thank you for the insightful responses to my query. I must say, the answers aren't a huge surprise to me -- given the age of the Vari-Eze and its ancestors, it would likely be a mod I've read about.

The explanation about canard loading makes a great deal of sense. I suppose I should have figured that one out on my own, but I'm new to considering a canard.

For the poster above: No, I've never gotten to fly in any of the EZ-type aircraft. I sat in one in an airshow once. The look and cross country performance are whatattracted me to the build -- plus I'm interested in getting a Mazda 13B to work on an airplane, and it matches up nicely with the EZ, performance wise.

Waiter's sig actually sums up what I'm shooting for: F-16 performance on a piper cub budget. Actually, considering the prices of Cubs and Super Cubs these days, let's hope it's cheaper than that.

The reason for a steerable nosewheel is simple: I'm used to it. I can see how relying on differential braking would work just fine, though.

The retract nose gear is a concern for me. I suppose I'll just build the Wright (or equivalent) electrical easy lift into my plane from the start, and build in some rock solid warning systems.

Thanks for the replies, folks. Now, if someone can release a set of plans that would let me build my plane to Berkut standards, I'd be in heaven. 300 knots sounds good to me. Gives me an excuse to find a 3 rotor turbo mazda engine.

If anyone in the Anchorage area has an EZ and is willing to demo it, I'd happily pay your expenses for an hour, and throw in dinner at Simon and Seafort's.

Last edited by Northman : 05-25-2007 at 02:07 AM.
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  #8  
Old 05-25-2007, 04:06 AM
chasingmars chasingmars is offline
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Quote:
The reason for a steerable nosewheel is simple: I'm used to it. I can see how relying on differential braking would work just fine, though.
This seems to be a big predictor as to whether people like pivot vs. steerable, what they've flown to date. I fly Katana's so I'm used to pivot and love the ability to turn the plane on a dime, especially as rwy 04 at YOW requires me to do my runup pretty much on the taxiway, I can get turned into the wind, and turn back out, without going anywhere. I worry about crosswind landings and such if I ever were flying steerable, but I probably shouldn't, I'd learn...

I'd bet after a bit of taxi-ing a pivot nosewheel, you'd be just as comfortable with it. Before you embark on such a mod, might be worthwhile to find a type with pivot nosegear and try it - you just might like it.

Quote:
The retract nose gear is a concern for me. I suppose I'll just build the Wright (or equivalent) electrical easy lift into my plane from the start, and build in some rock solid warning systems.
Electric from the start is a lot of peoples' plan, including mine. Remember that while not what you *want* to do, a (nose) gear up in a cozy/long usually isn't disasterous, just embarassing. Read peoples sites, and you'll find that it's happened to a fair number of flyers, but generally without huge damage, so it's not like you're trashing your engine on a gear up (assuming it's just the nose) All told, plans plus electric lift is a pretty good compromise.
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  #9  
Old 05-25-2007, 08:18 AM
Wayne Hicks Wayne Hicks is offline
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Differential steering takes about 1 minute to get used to. Once you do it, you'll never go back to nosewheel steering.
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  #10  
Old 05-25-2007, 08:54 AM
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Quote:
Originally Posted by Nathan Gifford View Post
IAnother issue are the differential rudders. Velocities have steerable nosewheels and no differential rudders.

Actually, Velocity's do not have steerable nose gear. What the Velo Corp. folks have now added (was an option, but now I think it comes standard) is the toe brakes. With this option/feature (?) I believe you do loose differential rudders. My Velo does not have toe brakes and I will be steering with my brake/rudder pedals. FWIW.

All the best,

Chris

added fluids (oil & coolant) to the rotary, cranked it and got oil circulating 'round the plumbing. Should be moving the fuel lines from "dry fit" to sealed, tonight. Then, I will add fuel to the sump and see if I can make this thing make noise on its own pretty soon. (I may have the local jet jockeys from the TX ANG and NASA coming by complaining MY engine is too loud
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  #11  
Old 05-25-2007, 10:12 PM
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David Staten David Staten is offline
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Quote:
Originally Posted by Wayne Hicks View Post
Differential steering takes about 1 minute to get used to. Once you do it, you'll never go back to nosewheel steering.
AMEN.


I could taxi a Grumman Cheetah/Tiger (with pivoting nosewheel) into much tighter spots and in a much tighter radius than any CessPipeBeeMooPlane.

If I was willing to sacrifice a smidgen of rubber, I could pivot the plane on a locked main gear in a tight circle.

Makes moving with a towbar a more capable feat too.
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Old 05-26-2007, 10:21 AM
Nathan Gifford Nathan Gifford is offline
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As far as nose gear up landings, there are systems to deploy the gear at 90. Also, builders are adding skid plates that minimize damage from gear up accidents.

There are times where deliberate gear up landings are an option. When you really need to stop the plane fast in an emergency you land with the gear retracted. My guess is that most new builders are building their aircraft with skid plates, these minimize damage.

The standard mechanical retract has an additional advantage in that if during landing you need to perform an emergency retract, you only need unlock the retract mechanism a few turns. The weight of the nose will strip out the retract mechanism and the plane will promptly settle on its nose. More to repair, but a very quick stop.
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Old 05-26-2007, 10:41 AM
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Quote:
Originally Posted by Nathan Gifford View Post
More to repair, but a very quick stop.
Just to add to that, a few pieces of kevlar added to your layups around the area of likely contact will improve the durability of that area a lot.
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Old 05-26-2007, 11:57 AM
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Just to add to that, a few pieces of kevlar added to your layups around the area of likely contact will improve the durability of that area a lot.
You know, I heard that somewhere else, but has anybody actually tried it and found that kevlar reacts better to a hard grinding (abrasive) force than other fibers? I thought it strength lie in other areas.

I did however see an ad for a ceramic coating that goes on the bottom of boats to prevent damage from beaching. That would be an abrasive force for sure. It uses an epoxy base. Hmmm.

It would seem that besides the raw abrasive effect, there is heat generated too. Probably enough to melt the epoxy or at least make it stink! What would happen to the kevlar plies I wonder?

It would be nice to know for sure if it actually helps enough to make it worth the effort.
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Old 05-26-2007, 12:30 PM
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The Infinity 1 has 3 plys of Kevlar on the bottom of the fuse (as does the Berkut) for damage protection in the event of a gear up landing.
The two PIAs are cutting it and sanding it. Kevlar shears will get you past the first on and a final layup of glass over the Kevlar will get you past the second. Kevlar has a tendency to fuzz up if you sand it. I've also read where a very fine grit sandpaper will help avoid this as well.
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