All Discussions Tagged 'dual' - Zenith Aircraft Builders and Flyers2024-03-19T14:00:01Zhttps://zenith.aero/forum/topic/listForTag?tag=dual&feed=yes&xn_auth=noThoughts on dual brake calipers...tag:zenith.aero,2021-01-04:2606393:Topic:7998782021-01-04T15:33:24.100ZDavid J. Beaulieuhttps://zenith.aero/profile/DavidJBeaulieu
<p>Happy New Year fellow "Z"s!</p>
<p>Am considering going with dual brake calipers on my standard stock STOL750 with single caliber Matco brake assembly and Turf-Glide tires. The Matco wheels are rated for the change to dual calipers and Matco makes the assemblies for the change relatively easy. My question to ponder is this - what real advantage will I be gaining in doing the change to dual calipers? I ask this because I find that the light weight of the aircraft, tire surface area contact…</p>
<p>Happy New Year fellow "Z"s!</p>
<p>Am considering going with dual brake calipers on my standard stock STOL750 with single caliber Matco brake assembly and Turf-Glide tires. The Matco wheels are rated for the change to dual calipers and Matco makes the assemblies for the change relatively easy. My question to ponder is this - what real advantage will I be gaining in doing the change to dual calipers? I ask this because I find that the light weight of the aircraft, tire surface area contact with the ground and friction of the ground surface all combine to allow the aircraft to "skid" forward (brakes are locked and wheels not rotating) during close to full power runups. It seems that the physics of the problem boil down to lack of suitable friction between the tire and the ground and not the energy dissipation capability of the braking system. Admittedly, the total energy of a landing aircraft is much greater than during a static runup and requires more energy dissipation overall, but I just can't see any obvious substantive advantages of going to dual calipers with the wheel/tire combo for short field landings. Let's discuss...! As always, thanks for all thoughts and opinions.</p>
<p>Dave</p>
<p>Mighty "Sky Turtle" 826DE</p> * * *EA81 DUAL pickup distributor WANTED * * *tag:zenith.aero,2018-09-19:2606393:Topic:6462492018-09-19T14:15:19.702ZGlen Rushinghttps://zenith.aero/profile/GlenRushing
<p></p>
<p>Looking for a Subaru EA81 Distributor for sale that has <span style="text-decoration: underline;">already</span> been modified to include DUAL MAGNETIC PICKUPs in the distributor?</p>
<p></p>
<p> OR: Does anyone have any documentation with good photos that shows exactly step by step, how to modify my distributor so it has DUAL Magnetic Pickups so I can selective power dual coils?</p>
<p></p>
<p>THANKS!</p>
<p>Glen Rushing</p>
<p>Tallahassee, Florida</p>
<p></p>
<p></p>
<p> </p>
<p></p>
<p>Looking for a Subaru EA81 Distributor for sale that has <span style="text-decoration: underline;">already</span> been modified to include DUAL MAGNETIC PICKUPs in the distributor?</p>
<p></p>
<p> OR: Does anyone have any documentation with good photos that shows exactly step by step, how to modify my distributor so it has DUAL Magnetic Pickups so I can selective power dual coils?</p>
<p></p>
<p>THANKS!</p>
<p>Glen Rushing</p>
<p>Tallahassee, Florida</p>
<p></p>
<p></p>
<p> </p> Dual Bungee Nose Gear Suspensiontag:zenith.aero,2016-08-16:2606393:Topic:5221102016-08-16T14:58:39.559ZJohn Austinhttps://zenith.aero/profile/JohnLAustin
<p>A popular, recurrent topic in the Forums centers around the Zenith nose gear bungee suspension design. As I always say, Chris Heintz is the master of simplicity and lightness and you can't get much lighter than his bungee system! As with all designs, there are some inherent compromises:</p>
<ol>
<li>The bungee is a single-point failure system.</li>
<li>Bungees seem to be unpredictable as to durability and failure, and deteriorate more rapidly with exposure to heat and oil.</li>
<li>Bungee…</li>
</ol>
<p>A popular, recurrent topic in the Forums centers around the Zenith nose gear bungee suspension design. As I always say, Chris Heintz is the master of simplicity and lightness and you can't get much lighter than his bungee system! As with all designs, there are some inherent compromises:</p>
<ol>
<li>The bungee is a single-point failure system.</li>
<li>Bungees seem to be unpredictable as to durability and failure, and deteriorate more rapidly with exposure to heat and oil.</li>
<li>Bungee replacement requires disassembly/removal of the nose gear.</li>
<li>The single bungee imparts some torque resistance to the nose gear turning.</li>
</ol>
<p></p>
<p>A popular alternative is the "steel bungee," which does not require periodic replacement, is unlikely to break, and induces no additional resistance to steering inputs. The only disadvantages are weight (I've seen 3.5 lbs quoted?) and expense.</p>
<p></p>
<p>An alternative bungee design may seem strange coming from me, since I have the Zenith single bungee system and it works perfectly! My rudder is silky-smooth and I and other pilots I've asked to fly it cannot detect the centering notch in the bearing support. However, I have had one bungee break (it was a non-event - had 9" prop clearance after breaking) and since some do have bigger problems, I was determined to see if a new design could offer some improvements while keeping weight and costs down.</p>
<p></p>
<p>Here's a sketch I came up with:</p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/2060775573?profile=original" target="_self"><img width="750" src="http://storage.ning.com/topology/rest/1.0/file/get/2060775573?profile=RESIZE_1024x1024" width="750" class="align-full"/></a>I've already thought of some improvements to this design:</p>
<ol>
<li>Make the nylon bearing a slip-fit on the nose gear leg, but over-size the steel rotating collar's hole so it does not touch the nose gear leg (the steel rotating collar will be shaped similar to a 2-bolt exhaust manifold flange). The nylon could be flush riveted to the collar or even simpler, be shaped the same as the steel collar and utilize the same bolt holes as the steel collar to secure them together in alignment.</li>
<li>Rather that suspend the bungees from "hooks," which might concentrate too much pressure/too sharp a bend on the bungee, weld up a tube with a tang on the end (such as is currently used on the back of the nose gear leg) to hook the upper end of the bungee on. The tube could be welded to a flat metal strap with a bolt welded to the top of the strap to allow the bolt to pass through the rotating collar and allow removal and adjustable pre-load:</li>
</ol>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/2060775653?profile=original" target="_self"><img src="http://storage.ning.com/topology/rest/1.0/file/get/2060775653?profile=original" width="374" class="align-full"/></a></p>
<p></p>
<p>While still using bungees, there are some advantages to this design:</p>
<ol>
<li>Minimal weight increase, minimal cost increase.</li>
<li>No single point failure. If one bungee breaks, half the support is still there vs. none! </li>
<li>Allows easy bungee removal/replacement without removal of the nose gear, encouraging routine periodic replacement</li>
<li>Tensioning and pre-load are accomplished with a nut on the bungee hook bolt (and locked-in with a jam nut). Negates the need for special tools to stretch and hook the bungee in place and also doesn't require a lot of room between the engine and firewall to accomplish this.</li>
<li>I talked to <a href="http://www.sbcindustries.com/index.htm" target="_blank">SBC Industries</a> about the design and was assured the two smaller bungees (which, for the same amount of suspension travel, will stretch roughly proportionally the same as the single bungee) would perform similarly to the single bungee. SBC said my design "was much better" since I could adjust the pre-load and tweak the suspension as necessary! He also liked the fact that the bungees are working in a straight line and there are no torsional loads! He also said the smaller #9044 bungees are conservatively rated and 2 would be perfect substitutes for the single #1280HD.</li>
</ol>
<p></p>
<p>Some unresolved questions/problems</p>
<ol>
<li>I think there is only about 1" clearance on each side of the nose gear leg - this would mean the "hook" for the bungee would have to be kept to minimal dimensions to avoid interference with the support alongside the nose gear leg. Thankfully, the smaller bungees are also smaller in diameter, which helps. Also, I'm assuming the two bungees would more-or-less keep the rotating collar aligned - slight fore and aft movements would be OK, but one would have to ensure there is no possibility of jamming or locking the nose gear leg if one bungee breaks - probably unlikely with the nylon bearing preventing the steel collar from touching the nose gear leg.</li>
<li>I show the bearing support welded immediately above the present bungee hook tubes. Likely one would have to put the two bungees in a test rig with a scale and stretch them to determine the pre-load length and to establish the bearing support placement. This same rig could also be used to determine the load at maximum suspension travel to ensure the test ratings are not exceeded</li>
</ol>
<p></p>
<p>This is merely an experimental and speculative design at this point. I'm thinking this might be an interesting winter project. I'd be interested in comments, constructive criticism and suggestions as I refine the design! </p>
<p></p>
<p>Fire away!</p>
<p>John</p>
<p>N750A</p>