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Old Sep 04, 2011, 09:48 AM
Owner of CFC Graphics
Florida
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Landing gear and issues?

Hard landings can certainly damage areas of the wings where the retracts are attached.

My guess is, most damage is blamed or attributed to hard landings. Possibly?

Certainly poorly designed gear/struts or gear/struts which doesn't function properly could also be the cause of damage.

Has anyone experienced damage, to the area where their gear is attached, possibly because of poorly designed gear/struts?

There's many gear/struts available, and I'm trying to do an evaluation.

Thanks,

Charles
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Old Sep 04, 2011, 08:11 PM
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I think most of the damage is caused by pilots doing carrier style landings. I've watched too many to count and they all start out with lousy approaches.
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Old Sep 05, 2011, 08:37 AM
Owner of CFC Graphics
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Luv,

Correct, you do have to know a bit about landings and how the model reacts.

However, I'm guessing there's a story to be told from what I see in the way gear is designed.

Input from individuals is necessary.

Charles
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Old Sep 05, 2011, 02:17 PM
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well, the strut is designed simply to take away the shock of hitting the ground, but it doesn't do anything about the inertia transfer. it's the transfer of intertia that causes all of the damage. furthermore, it's the design of the aircraft that dictates what this transfer of inertia does to the structure. I've seen many poorly designed airplanes, that had no hope of survival. the problem is that a lot of folks don't seem to grasp the concept of some sort of carry through structure, that allows this force to be disippated smoothly and evenly across the whole structure. you need a solid structure, that not only goes from one side to the other, but also ties solidly to the fuselage aswell. this will allow the force to distribute evenly across the whole airframe, rather than be confined to a single area, causing damage to that area.

also, remember that for every action, there is an equal and opposite reaction. so if you see damaged struts, it's because the strut wasn't working properly and the airframe was. so the force is able to concentrate in the strut, damaging it.
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Old Sep 05, 2011, 02:30 PM
Owner of CFC Graphics
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Luv,

Right at the moment, there are 63 people viewing. Where are they all? They got some secrete place.

I see Threads that are months old with a thousand hits and only 12 replies.

How does one digest shared information with results like this?

I'm designing my own gear struts for my model. Not because I want to, but because I see nothing available that suites my needs.

I'm not the best pilot so I need backup in great operating gear. I don't like repairing models that I've finished.

Charles
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Old Sep 05, 2011, 03:02 PM
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If you fly from any sort of un-improved runway surface (grass, gravel, dirt, mud, whatever) do yourself a favor and run a trailing link style gear. They absorb a TON of abuse w/o doing much damage to the model.

My current eurosport has trailing links on it, my previous one had straight struts. I fly from a fairly smooth grass runway, but with my previous eurosport, it sounded like someone was using the wings as drums from all the abuse the struts were transferring into the wing from the runway surface, Even at a SLOW taxi speed.. With the new euro and trailing link, its quiet as can be even during take-off and landing speeds.

A couple of thinks in mind.

Hard landings are ALWAYS going to damage the weakest link, the thing you have to decide, is what do you want to consider "hard" and what would your rather replace/repair.

The more surface area you can spread the loads into the less chance's their are of damaging the mounting structure.

IMO BVM has soem of the best designed gear mounting setup's in their jets. The use of their flex-plates that bolt to the wing/fuselage and then the gear to the flexplates allows them to take allot of abuse and damage w/o destroying the wing structure.
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Old Sep 05, 2011, 03:47 PM
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Look at this flight starting at about 3:15. He is flying a 1/4 scale f16. The problem there I feel is he was trying to slow this thing down waaaayyy to much and over compensated for the lack of speed with a boat load of elevator. PIO with the help of the ground. Surprised this aircraft survived..... And then they clapped at the end?? I would have walked away shaking my head.

Luv and Invertmast hit the nail on the head. You don't need a ton of people to respond to come up with a design.
Look at real aircraft for design inspiration. The F-18 has some of the most rugged gear I have ever seen. It is a trailing link gear that allows for a ton of movement and protection from the carrier landings.
When I flew the Citation Ultra with straight legs you could feel every little bump and poor landing was extremely noticeable. Everything was transferred to the wing and then to the fuselage. The Citation Bravo with trailing link gear REALLY made a difference in the transfer of taxiing/ landing anomalies to the airframe.

So..... Build a structure that will distribute the loads of taxiing/ landing to the airframe and if you really want to protect the structure trailing link gear is the only way to go in my opinion.

Neil
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Old Sep 05, 2011, 03:53 PM
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you notice that mostall full size aircraft that are designed for high abuse, such as carrier landings, semi-prepared strip and rough field capability have a trailing strut design. think of the F-18, Sepecat Jaguar, some Russian designs, French designs and the list goes on. as stated, it's the easiest way to transfer energy to the airframe and also handle return energy.
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Old Sep 05, 2011, 04:37 PM
Owner of CFC Graphics
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The gear I'm drawing up is of the trailing link design. I've already Posted a drawing. In fact, I'm trying to get a Manufacturer to pick it up and run with it.

I believe, at least in most cases, the struts available are fixed to the retracts and NOT attached to a 5/32 steel wire that has a "recoil" loop.

Remember these recoil loops. They are needed.

Charles
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Old Sep 05, 2011, 06:08 PM
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Quote:
Originally Posted by avaiojet View Post
The gear I'm drawing up is of the trailing link design. I've already Posted a drawing. In fact, I'm trying to get a Manufacturer to pick it up and run with it.

I believe, at least in most cases, the struts available are fixed to the retracts and NOT attached to a 5/32 steel wire that has a "recoil" loop.

Remember these recoil loops. They are needed.

Charles
Recoil loops aren't needed IMO. If your doing a trailing link gear, those ARE your recoil loops. Now if your doing straight struts, they still aren't needed if the design is done right (IE, it needs some "flex" but not any "give")

look at full-scale aircraft with straight struts. No recoil loops... F-86, F-16, F-15, F-14, etc no recoil loops.


While most navy carrier jets are using trailing link now, the F-14 and A-6 intruder did not. In-fact the F-14 had what they called a "gotcha" brace. When weight was point on the main wheels and the struts began to collapse, this brace would fold out and then lock into a casting in the side of the nacelle. This kept the landing gear from splaying outwards from the force's of the landing. since the A6 / F-14 essentially used the same landing gear, i wouldn't be surprised if the A6 had the same thing.
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