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Building Tips and technical articles. => Building techniques => Topic started by: Matt Brown on July 23, 2021, 04:52:02 PM
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Looking for landing gear mounting info on my profile Vector kit.
Plans provided are the full fuse plans so they don’t really help. The gear mounts to the side of fuse as you’d expect but there is a 3/8” balsa tripler on the inboard side of the fuse. If I cut away the tripler for the gear, it would be defeating much of it’s structural advantages. I could mount the gear and relieve the tripler for clearance and mount the tripler over the gear but that would make the gear more or less permanent and would be a pain to work around during sanding and painting.
Any other suggestions/ideas?
Thanks Matt
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Matt notch the tripler mount gear to ply doubler and be you glue
the doubler on notch the fuse for a 1/2''ply in the fuse than glue on
doublers on
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Matt notch the tripler mount gear to ply doubler and be you glue
the doubler on notch the fuse for a 1/2''ply in the fuse than glue on
doublers on
I already epoxied the ply doublers on. I put in some 1/2” dowels for hard points. If I mount the gear legs they will always be in the way during finishing unless I’m not understanding what you are saying.
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Make a new landing gear strut for the tripler side and tap the holes for the mounting bolts. Then you can hollow out just enough space in the tripler to clear the strut which will leave the tripler largely intact structurally. The bottom bolt hole will be mostly exposed if you contour the tripler so you can put a jamb nut on there if you're uneasy with tapped holes in aluminum. It's the bottom bolt that takes the beating in a hard landing; the top bolt just keeps the gear from flopping around when there's no load on it.
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Make a new landing gear strut for the tripler side and tap the holes for the mounting bolts. Then you can hollow out just enough space in the tripler to clear the strut which will leave the tripler largely intact structurally. The bottom bolt hole will be mostly exposed if you contour the tripler so you can put a jamb nut on there if you're uneasy with tapped holes in aluminum. It's the bottom bolt that takes the beating in a hard landing; the top bolt just keeps the gear from flopping around when there's no load on it.
Not a bad idea! I’ve got some 3mm PEM nuts that are pressed into place and work well in aluminum. Unless someone comes up with something that sounds even better, this will be my choice.
Matt
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Mount the gear legs as you normally would. Plan on the nuts being on the outboard side. Where the tripler will be over the inboard leg, releave enough wood so the tripler can be epoxied securely, the transfer the hole locations to the tripler. At this point, drill holes where the bolts are so that they can fit through and the bolt heads seat against the gear leg. Fine tune the fit so that when the bolts are removed that the gear can slide out for finishing and servicing later on. For the holes to look nice, you can sleeve them with any kind of tubing so that they toughen up the area so you don't dent the wood putting screws in and taking them out. Just make sure the tube is big enough for the heads of the bolts. When sanded off, and the model is dope and painted, it helps give a more finished look to the holes.
Type at you later,
Dan McEntee
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I put dowels through the fuse where bolts go. Used blind nuts on the inboard leg. Hogged the the cheek block to clear the gear . Painted, the bolted the gear.
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A lot of this may depend on your flying surface and skill level but I have found over the years that LG mounts that are made too strong do more damage in a "hard landing" than they prevent. On a normal flight your gear takes less stress than a flap hinge and in a not so normal landing they can be the reason the nose breaks off or a wing is destroyed and for that reason I use wire gear on a profile or mount them on the bottom RC style. First, the purpose of the trippler is mostly cosmetic and vibration absorption except at the wing joint and cutting back to the plywood is not going to affect that much where the gear is mounted. The mistake a lot of us make is not tapering the trippler to match the wing so that it glues on without a gap or we fill the gap with blue stuff.
So here is my solution - very similar to Dan's, ( and his is better IF you had not already glued on the trippler. So mark the gear location on the block and cut it out back to the doubler. Cut a piece of 1/8" bass to cover the gear and slide it in over the gear for a snug fit forming a box that will allow the gear to slide out. Epoxy that in from the outside so that you don't glue gear in. (Keep any CA in the next room). Now drill from the outboard side through the bass and put blind nuts on the insert. Now fill the rest of the gap with scrap balsa. Sand and finish - don't forget the wing gap. Tightly cram it with scrap balsa glued in not Blue Stuff. If you are going to glass the nose (recommended) do it after adding a fillet, it will be stronger.
One other piece of hard learned advice. The oil from an IC will find a way to seep into any hole you make in the nose given enough time. Dan suggested aluminum bushings - use them.
Ken
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My favorite failure mode is tearing the alum. LG off a full fuselage model and have it roll under the fuselage and tear the horizontal tail to bits. I'd rather the LG stay where I put it, partly because repairs do less damage to the CG location. D>K Steve