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Grove Spring Gear

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Posted

Guys,

I'm looking at the grove spring gear for my Avid Magnum.

Can someone, with the Grove gear, give me the pros and cons?

I'm planing on buying 26" tires for it, and I want to use it for backcountry flying here in Colorado.

Does this gear have a tendency to bend the bottom longerons?

My only other options would be building a new, wider and taller bungee gear, or building a cabane style wider and taller gear.

I am leaning toward the cabane style gear, but it sure would be easier to buy the proven grove spring gear.

Thanks,

Ron

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Posted

Guys,

I'm looking at the grove spring gear for my Avid Magnum.

Can someone, with the Grove gear, give me the pros and cons?

I'm planing on buying 26" tires for it, and I want to use it for backcountry flying here in Colorado.

Does this gear have a tendency to bend the bottom longerons?

My only other options would be building a new, wider and taller bungee gear, or building a cabane style wider and taller gear.

I am leaning toward the cabane style gear, but it sure would be easier to buy the proven grove spring gear.

Thanks,

Ron

I have grove gear on my Magnum with 800X6's and optional 29 inch bushwheels. I love the fact that it opens up the entire bottom of the plane to carry my kayak. As far as handling characteristicsI am more a fan of the bungee type gear because there is no movement until it is deflected during landing. Grove gear is kind of spongy during ground handling. So I would prefer bungee gear for for its handling characteristics, but prefer grove for its practicality and the versatility for cargo carrying. Grove gear is also much heavier.

One thing to note is that you will have to modify the fiberglass boot cowl 9bottom of plane) to use grove gear, unless you got the original spring brackets from Avid for the grove gear. The grove brackets place the spring an inch or so higher up under the fuse and it will interfere with the fiberglass. It will be a pretty big job in terms of glass work to make it work. My plane had the Avid brackets which were designed around the Avid cowl so the spring fits fine. When I wrecked my Magnum, it runied the stock speing brackets and I had to buy grove replacements. That's how I found out about the fit difference.

If your concern is bending anything where the gear attaches, I can assure you that the whole plane will end up wadded up in a ball before anything in the area of the gear truss structure will bend!

All in all, if you do not plan to carry cargo or a boat under the plane, I think you will be happier with Bungee gear and not have to modify the cowl.

ChrisB

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Posted

I have grove gear on my Magnum with 800X6's and optional 29 inch bushwheels. I love the fact that it opens up the entire bottom of the plane to carry my kayak. As far as handling characteristicsI am more a fan of the bungee type gear because there is no movement until it is deflected during landing. Grove gear is kind of spongy during ground handling. So I would prefer bungee gear for for its handling characteristics, but prefer grove for its practicality and the versatility for cargo carrying. Grove gear is also much heavier.

One thing to note is that you will have to modify the fiberglass boot cowl 9bottom of plane) to use grove gear, unless you got the original spring brackets from Avid for the grove gear. The grove brackets place the spring an inch or so higher up under the fuse and it will interfere with the fiberglass. It will be a pretty big job in terms of glass work to make it work. My plane had the Avid brackets which were designed around the Avid cowl so the spring fits fine. When I wrecked my Magnum, it runied the stock speing brackets and I had to buy grove replacements. That's how I found out about the fit difference.

If your concern is bending anything where the gear attaches, I can assure you that the whole plane will end up wadded up in a ball before anything in the area of the gear truss structure will bend!

All in all, if you do not plan to carry cargo or a boat under the plane, I think you will be happier with Bungee gear and not have to modify the cowl.

ChrisB

Chris,

Thanks for the words! I do like your kayak idea! I think I saw pics of you mounting the kayak to the bottom somewhere. That is awesome.

I was worried about the gear putting excessive forces on the mounting points, but it sounds like it is a sturdy setup.

So cons are, costs, modifying the cowl, and weight.

I can live with those, because all of the other options involve me custom building a gear.

I love the bungee gear I have on another plane, but I always worry about that bungee snapping. I know you can put a safety cable in there, but it still bothers me!

I'm intrigued by the cabane system...but I don't know if I want to design my own.

So I'm thinking grove spring gear wins! Any last minute don't do its?

Thanks

Ron

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Posted

Having converted from bungee to grove on my Kitfox all I can say is I would never go back!

My plane gained only 12 pounds but the difference is amazing in the ground handling and landings. I now have "real" aircraft wheels and brakes that actually work. The old ATV wheels and brakes at best sucked and at worst were dangerous. I prefer the softer ride of the grove spring on the ground and the added width is far more stable.

I am planning a grove set for my project as you can see in the other thread.

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Posted

Robby Grove will make you a custom gear - If you dont want the standard for your model, you can use his order form to change height, width, GW, etc, or get his input in the design.

Imagine the cost will be in line with the stock gear.

He is very knowledgeable and easy to talk to.

ED in MO

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Posted

Robby Grove will make you a custom gear - If you dont want the standard for your model, you can use his order form to change height, width, GW, etc, or get his input in the design.

Imagine the cost will be in line with the stock gear.

He is very knowledgeable and easy to talk to.

ED in MO

Thanks Guys...

I'm going to call Robby and ask him some questions.

Ron

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Posted

Guys,

I'm looking at the grove spring gear for my Avid Magnum.

<snip>

Does this gear have a tendency to bend the bottom longerons?

<snip>

Thanks,

Ron

Ron- I can't answer about the Magnum specifically. However, I can tell you with 100% certainty that the lower longerons on the earlier Avid/Kitfox models can not handle a hard horizontal, backwards force on an unmodified fuselage without something bending. Pics of my encounter with a ditch/hole at ~50mph attached for the rubberneckers.

If your concern is bending anything where the gear attaches, I can assure you that the whole plane will end up wadded up in a ball before anything in the area of the gear truss structure will bend!

ChrisB

Chris- thankfully, in my case, pretty much everything else was undamaged so I bought the salvage and parted out the plane. This is why I am so vocal about reinforcing the fuse sides under the doors. Probably equally important for Grove spring gear users as reinforcing the bungee truss is to any (oem, Airdale's W.I.B., or homebrew) bungee gear users.

post-53-13612937439545_thumb.jpg

post-53-1361293745117_thumb.jpg

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Posted

Ron- I can't answer about the Magnum specifically. However, I can tell you with 100% certainty that the lower longerons on the earlier Avid/Kitfox models can not handle a hard horizontal, backwards force on an unmodified fuselage without something bending. Pics of my encounter with a ditch/hole at ~50mph attached for the rubberneckers.

Chris- thankfully, in my case, pretty much everything else was undamaged so I bought the salvage and parted out the plane. This is why I am so vocal about reinforcing the fuse sides under the doors. Probably equally important for Grove spring gear users as reinforcing the bungee truss is to any (oem, Airdale's W.I.B., or homebrew) bungee gear users.

The Magnum is an entirely different animal than the MKiv or the Fat Avid. I have owned all three. The landing gear structure is INCREDIBLY strong and resiliant in the Magnum. Chris

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Posted

Ron- I can't answer about the Magnum specifically. However, I can tell you with 100% certainty that the lower longerons on the earlier Avid/Kitfox models can not handle a hard horizontal, backwards force on an unmodified fuselage without something bending. Pics of my encounter with a ditch/hole at ~50mph attached for the rubberneckers.

Chris- thankfully, in my case, pretty much everything else was undamaged so I bought the salvage and parted out the plane. This is why I am so vocal about reinforcing the fuse sides under the doors. Probably equally important for Grove spring gear users as reinforcing the bungee truss is to any (oem, Airdale's W.I.B., or homebrew) bungee gear users.

Dholly,

Holy bent longeron Batman! That is exactly what is worrying me. I am thinking about a custom Grove gear that is slightly taller than the standard, but I know the taller I make it the more the force will be on the aft mounts. I sure wish I had a third mount so I could distribute the weight over a longer area.

What are you suggesting be done for reinforcement of the longerons?

Did you almost go through the top plexi on that landing, or did it just come to an abrupt stop? We're you injured? I'm sorry that happened to you, thanks for sharing though!

Chris,

You are right, the Magnum is built tougher, to handle the higher gross weight, but the gear geometry is just awkward. I wonder why they designed the mounts so close together?

Thanks for all the discussion, and for the heartbreaking pics!

Ron

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Posted

This is what I did to add strength for my Grove setup. Post #53

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Posted

Ron- No injuries except the wallet. To be honest, after taxiing out of the field and then looking closer, I was shocked at the extend of damage vs. the fairly minimal 'seat-of-the-pants' jolt experienced. Remember, this was not a hard pancake landing or vertical force, rather, a horizontal front to back and twisting motion on the gear. I guess the large amount of twisting moment absorbed most of the impact energy, but I sure do remember thinking "S#!t, that didn't sound good!". In any event, I believe the reinforcing side plates shown in Av8r3400's link would most certainly have helped minimize and perhaps even prevented my damage with the spring gear.

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Posted (edited)

Ron,

I have the Avid Magnum builder manual, but cant honestly say that I ever paid attention to how the gear was attached - just assumed it was like earlier Avid & Kitfox. My KF2 had a minor sideways landing gear bump when it landed in a soybean field and grabbed the highdob in the bean row - this did major damage to one longeron and the middle cross tubes.

I posted photos of my new build, see "Foxy Flapper Fotos" somewhere in this site, maybe under "Kitfox IV" - I made the forward longerons stronger, the bottom crosstube stronger, and added three 3/4 x 2 rectangular stubes between the strut attach tube and a new tube (I only needed two) to modify mine to take the mounts like the Kitfox 7 radius blocks for the grove gear. Only time will tell how this works out. You might check out the later Kitfoxes gear attachments.

Robby Grove told me that moving my attach points closer together about 3 or 4 inches would not matter on the performance of the gear.

My KF1 tried a tree-landing, and bent hell out of everything, so the only thing learned there is to stay out of trees when landing!

ED in MO

Edited by Ed In Missouri

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