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the gear. Initially, it worked the sameon the LSM cowl. Then it was discoveredthat in flight, the gear was beingsucked down by low-pressure air flowingover the nose-gear door. That ledto a design change in which the nosegeardoor has its own extend/retractactuation system. A firewall-mountedelectric motor drives a series of rodsthat open and close the door insequence with the gear. The doormotor is activated by the gear handleswitch, but a'separate gear door handlemust be pulled before releasing theemergency gear extension system.The stock Comanche does not havea cowl flap. Cooling air exits the enginecompartment from behind the nosewheel.Because that area is covered bythe long nosewheel door, theLSM cowl has a cowl flap. It'son the left side of the cowland looks monstrously largebut only because we're usedto cowl flaps beingunder the nose.hiddenThe GTO includes all LSMmods except aileron seals.Tests with the seals installedshowed a degradation of stallcharacteristics. Aileron sealsare offered for other Pipermodels, principally toimprove roll response. Allfairings and seals are made offiberglass and attached with•LSM'splastic surgeryenables the airplane togo a heck of a lot faster.New nosewheel doors necessitatedaddition of cowl flap (above). Flange onprop boosts induction air pressure.rivets and sealant. A Teflon strip isattached with adhesive to flap andaileron seals to reduce frictionbetween the sealaileron surface.and the flap orWhen I visited LSM, the GTO stillwore an "Experimental" stickerbecause of the unusual propeller. TheHartzell three-blade prop has a uniqueplanform with swept leading edgesand a small trailing edge flange oneach blade near the hub. The flange issupposed to give the air an extra pushas it enters the induction scoop. Thispoor man's turbo system sounds plausibleenough to a lay gearhead, butLSM has done it one better: The propis synchronized with the induction systemto ensure that the superchargedair travels through the inductionsystem to the cylinderintake valve with the least lossof energy. Synchronization isachieved by the timing positionof the prop, the locationof the induction inlet, and thelength of the induction systemducting.If all this sounds like anengineering sleight of hand,well, LoPresti won't claim tohave applied NASA testingtools and methods to verifythe theory. But he does contendthat precise measurementsof average manifold62 • MAY 1994
pressure show about a I-inch increaseat typical cruise speeds from the specialprop. The tuned prop, spinner,and induction system package adds5.5 mph (4.8 kts) to the Comanche'sspeed, according to LSM.LSM is developing the special propin partnership with Hartzell, and anSTC is expected sometime this summer.What does all of LSM's plasticsurgery do to a Comanche besidesmake it look like a current productionairplane? Based on what I observed, itenables it to go one heck of a lot faster.Curt LoPresti, LSM's chief designerand test pilot, and I, plus about 90 gallonsof gas, departed Vero BeachMunicipal and climbed at 110 KIAS.The 5-degree pitch attitude afforded anadequate view over the nose and a 900foot-per-minute rate of climb at loweraltitudes. Cylinder head temperaturesduring the climb appeared to be about350 degrees, judging by the InsightGEM EGT/CHT display. The headscooled as ambient air temperaturedecreased during the climb to altitude.The engine in the GTO is exceptionallysmooth for a 540-cubic-inchLycoming, perhaps due in part to theexperimental three-blade prop. Theonly changes to the cockpit related tothe LSM mods are the addition of ared emergency nose-gear-door releasehandle and a T-handle to open andclose the cowl flap.I sampled a couple of cruise altitudesand power settings. At 8,500 feet,full throttle (22 inches), and 2,500 rpm,with the mixture leaned to 50 degreesrich of peak (about 15.5 gallons perhour), the airspeed indicator stabilizedat 148 KIAS/ 170 mph. Backing off to2,400 rpm scrubbed a couple of knotsoff the speed. At 6,500 feet, full throttle(23.5 inches), and 2,400 rpm, I waslooking at 151 KlAS/174 mph.Back on the ground, we fed the datato Jim LoPresti's computer (LSM is afamily affair; along with Curt and Jim, athird LoPresti son, David, is involvedwith the company, as is Roy LoPresti'swife, Peggy), and it crunched out someimpressive true airspeeds: 171.5knots/ 197.6 mph at the higher altitude,and 170.4 knots/196.3 mph down lower.The LoPrestis tactfully pointed out thatthe speeds I recorded were a tad underthe numbers they had been seeing andwere not corrected for standard conditions.So be it, I said; what I saw is what Igot. Even so, these speeds representhealthy increases over a stock 260-hpComanche and in fact are typical of a300-hp Bonanza. Higher speeds on thesame horsepower mean an increase inrange and endurance on the same fuelcapacity, too. Not bad for a 29-year-old(referring to the airplane, of course).The LSM cowl does have a few drawbacks,in my opinion. The cowl flap isunsightly given its location, and the cowlflap actuator handle in the cockpit possiblycould bang against the right frontMOONEY MUSClEGiven his past affiliationwith Mooney Aircraft, itshould come as no surprisethat LoPresti hasplans to modify a Mooney.At the time of our visit tothe LSM shop at VeraBeach, the finishing toucheswere being put on a260-hp Lycoming 10-540powered Mooney 231. Theconversion will mean 50more non-turbochargedhorsepower for the 231.LSM's computer analysispredicts the airplanewill fly at 187 to 191 knotsat non-oxygen altitudes,largely due to a more efficientcowling being designed,according toLoPresti.
Page 2 and 3: planes. "We want to become the prem
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