Nosewheel Weights?

Started by sequoiaranger, March 27, 2011, 09:29:31 AM

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sequoiaranger

I searched a few pages back for this subject but did not see it--pardon me if it is a repeat.

Obviously real aircraft are a lot heavier and better-balanced than plastic models, but most of us who have made "tricycle landing gear" aircraft are aware that the model "wants" to sit on its tail rather than its nosewheel. It is up to "us" to "convince" the model to use the three points of contact intended.

Forgive me if I am too simplistic anywhere here, but the principle is that the model be just out-of-balance toward the nose, as "seen" from the main landing gear. Weight can easily be overdone, and imperil spindly landing gear, so go easy. Think of the main landing gear axle as the pivot point/balance point of a "teeter-totter". Using the principle of the lever, ANY weight forward of that point will be a bonus, but the farther away from that pivot point, the more "leverage" the same weight will gain. It is always better to use less weight farther from the pivot point, but we don't always have that option.

The nose cone is, of course, the best place, but don't overlook twin-engine nacelles, or even wheel wells that have space forward of the wheel axle.

Probably the best, cheapest, and most common weight is lead. I like lead sheet, as it is cut-able, bendable, and rollable. Automotive wheel-weights (lead and antimony) used for balancing tyres is very useful, and any tyre shop probably has "free" casts-off all over their floor. Fishing weights are cheap, and come in all kinds of sizes and shapes. Birdshot is small, compact, and can fit into small places, but you have to be careful to completely encase it lest your model becomes a "maracas" of moving particles.

Don't neglect lightening the rear as another way to "move" weight forward.  You can drill out heavy resin rears, or possibly substitute vac-formed parts that are lighter (I have done both of these).

I'll stop here and others can contribute their ideas.
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JayBee

How about somebody casting nose wheels in lead or white metal? That way you could add forward weight without stressing "spindely" u/c legs.
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Weaver

Think there are some weighted wheels, arn't there?

Another option for appropriate types is heavy cargo. I did this for my Avro-Cierva Dragonfly, because I eventually intend to have it flying in a diorama, so I didn't want to add any permanent weight. The cargo is removable:





The box is just Evergreen glued around a collection of lead strips.

I think somebody else did something similar with a fixed-wing model, but I can't remember who - sorry.
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philp

When I lived in Montana there was a spot just off base that people used to go shoot at.  I went through it one day when no one was around and picked up all kinds of spent lead bullets.  They were added to my cache of fishing weights.  Also pick up the odd wheel weight when I get the chance.

You can also find pre made weights if you have the right model.  Here is a link to one. While mainly 48th scale he does have a few for 72nd and at least one for 32nd.

Haven't tried the lead strips but found that you can get some with adhesive backing to stick them right in the kit with no muss.
http://www.michaels.com/Self-Adhesive-Lead-Strips/cp0271,default,pd.html
http://www.dickblick.com/products/pebeo-self-adhesive-lead-strip/
http://www.tracysworkshop.com/p-4158-decra-led-self-adhesive-lead-strip.aspx?affiliateid=10050

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kitnut617

Quote from: JayBee on March 27, 2011, 09:34:13 AM
How about somebody casting nose wheels in lead or white metal? That way you could add forward weight without stressing "spindely" u/c legs.

Anything made of lead or has lead in it that involves kids is an absolute no-no over here in N.A.  And not much different for the adult kids either  ;D
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beowulf

one other word of warning using lead.............never use CA to attach it....cos it reacts with the lead....veeeeery slowly!...............it grows that white crusty stuff like on a car battery, and eventually expand so much it will force the fuselage to crack open......can take years for it to get that far tho

rather than lead i use ball bearings........not quite as heavy as lead but still heavy enough to help
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The Rat

Quote from: beowulf on March 27, 2011, 12:11:19 PM
one other word of warning using lead.............never use CA to attach it....cos it reacts with the lead....

Heard that before, never tried it anyway. I usually pour white glue all around it, sometimes putty.
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Weaver

Oh yeah - Little Cars are doing a product called "Liquid Lead", which is actually very fine lead beads. The idea is that you mix the stuff with glue to get a very heavy substance which can, of course, be worked into a space of any size or shape. You could even "paint" it onto the underside of a cockpit floor in a helo or plane with a glass nose.
"Things need not have happened to be true. Tales and dreams are the shadow-truths that will endure when mere facts are dust and ashes, and forgot."
 - Morpheus in Sandman: A Midsummer Night's Dream, by Neil Gaiman

"I dunno, I'm making this up as I go."
 - Indiana Jones '

dragon

There are also some very interesting weight solutions to be found in the Model Railroad section of your local hobby shops: smaller lead bbs, lead impregnated "clay", etc.

Then again, one can employ "Scale Gravity" (somehow affix the nose gear to a base).
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Gondor

Quote from: Weaver on March 27, 2011, 01:56:39 PM
Oh yeah - Little Cars are doing a product called "Liquid Lead", which is actually very fine lead beads. The idea is that you mix the stuff with glue to get a very heavy substance which can, of course, be worked into a space of any size or shape. You could even "paint" it onto the underside of a cockpit floor in a helo or plane with a glass nose.

Now that is a good idea  :thumbsup:

Gondor
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NARSES2

Quote from: Weaver on March 27, 2011, 01:56:39 PM
Oh yeah - Little Cars are doing a product called "Liquid Lead", which is actually very fine lead beads. The idea is that you mix the stuff with glue to get a very heavy substance which can, of course, be worked into a space of any size or shape. You could even "paint" it onto the underside of a cockpit floor in a helo or plane with a glass nose.

I use something very similar. A guy on a club stand at UK shows was selling camera film tubes filled with 200 grams of lead micro beads. They will "flow" very easily into most spaces. Very good and effective. Should have enough to see me through  :thumbsup: He was still selling the stuff at a couple of shows last year.
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Mossie

I use lead solder, it's pretty soft so relatively easy to work to shape & you can cut it to length.  Like sequoiaranger says, I stuff it anywhere forward of the CoG.

The way I determine how much weight I need is to dry fit the major components together.  I then balance it on something thin & round like a paint brush or brass rod to determine the CoG.  I add weight until the CoG is forward of the main wheels then I usually add a little extra to allow for for any changes with adding minor components.  It makes sure you don't end up using excessive amounts & I've never had a tail sitter.

Quote from: Weaver on March 27, 2011, 01:56:39 PM
Oh yeah - Little Cars are doing a product called "Liquid Lead", which is actually very fine lead beads. The idea is that you mix the stuff with glue to get a very heavy substance which can, of course, be worked into a space of any size or shape. You could even "paint" it onto the underside of a cockpit floor in a helo or plane with a glass nose.

I worked at a place that mixed tungsten powder into an adhesive to make plasters that were opaque to X-Rays.  Made fantastic nose weight as it would role into a ball that you could shape to fit, but it's a long while since I worked there.  You could make your own version with Iron filings mixed into adhesive or putty.  Tungsten powder is available on the net & would be much heavier, it just tends to be expensive, although a 250g tub would go a long way.
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sequoiaranger

I can remember the nosewheel models of the '60's advising to use "clay" in the nose to balance the models. (I thought I still had one or two such in my collection, but rememered I had purged my collection of the big surge of models I did when I was a teen-ager--had some until about four years ago.) You could work clay into all kinds of spaces, but it was only moderately heavy. I learned to add those tiny, copper-coated ball bearings known as BB's, pushing them into the clay for more density. The only problem was that clay sometimes would un-stick from the plastic and rattle around inside the model (I'm thinking of a particular Me-262 I did where that happened), but that was a result of extensive "playing" (gee, WHO DOES THAT?) with it. I "cured" that with a custom-fitted length of sprue jammed up against the clay crosswise into the weight-cavity and glued on the ends (thus a styrene-to-styrene bond) to the inside wall, creating a "jail" for the weighty "prisoner".
My mind is like a compost heap: both "fertile" and "rotten"!

frank2056

I discovered that museum wax works well when you underestimate the amount of nose weight required, or if there just isn't enough room forward of the main gears for extra weight.

Museum wax is used (not surprisingly) in museums to hold down exhibits without permanently gluing them down (and causing damage). It's also used in earthquake country to help keep delicate bricabrac on the shelves. It's cheap stuff. I used it to hold down the nose gear on my Ha 207 and so far, it's holding.