E-flite/Hori­zon Hobby UMX F4F Wild­cat

This small war­bird is big on scale de­tails and per­for­mance

Model Airplane News - - CONTENTS - By Rich Urav­itch

This small war­bird is big on scale de­tails and per­for­mance

E-flite has in­tro­duced its lat­est of­fer­ing in a grow­ing line of UMX RC mod­els that em­ploy the now fa­mil­iar AS3X sta­bi­liza­tion sys­tem, which, like a gyro, al­lows a small light­weight air­craft to be safely and com­fort­ably con­trolled in wind con­di­tions that would keep even larger, non­sta­bi­lized mod­els grounded. Not that you would want to fly these diminu­tive cuties in con­di­tions that would re­quire full throt­tle to main­tain zero ground speed—only that you could. And the sys­tem re­ally does work!

This model, like most of its pre­de­ces­sors, has a molded foam struc­ture, is one piece, and comes pre­dec­o­rated with all paint and mark­ings. It’s made out of in­jec­tion-molded foam, much like the larger foam mod­els we see to­day. This adds frac­tion­ally to its all-up weight, but dam­age po­ten­tial seems to be sig­nif­i­cantly less. What you get in the box is a Bind-N-Fly air­frame to which you’ll only need to add a 2S 280mAh LiPo bat­tery to start fly­ing over your lo­cal ver­sion of Guadal­canal look­ing for Ze­ros! The land­ing gear is in­cluded, and it’s pre­in­stalled but re­mov­able.

Po­ten­tial pi­lots of the Wild­cat should be com­fort­able fly­ing a 4-chan­nel model, prob­a­bly plac­ing them in the “in­ter­me­di­ate” cat­e­gory, but I have no doubt newer fliers could han­dle it, with some ini­tial help look­ing over their shoul­der dur­ing trim flights.

IN­CLUDED IS A IN­STRUC­TION MAN­UAL THAT GOES INTO EVERY SETUP DE­TAIL YOU MIGHT EN­COUNTER, IN­CLUD­ING RE­CEIVER ARM­ING AND GET­TING THE CEN­TER OF GRAV­ITY COR­RECT; IT ALSO IN­CLUDES A HANDY “FIRST FLIGHT” CHECK­LIST AND A COM­PRE­HEN­SIVE “TROU­BLESHOOT­ING GUIDE,” WHICH AN­SWERS EVERY PROB­LEM OR DIF­FI­CULTY YOU’RE LIKELY TO EN­COUNTER.

UNIQUE FEA­TURES

As an ul­ti­mate ARF, there isn’t any­thing to as­sem­ble since it’s re­ally bind-and-fly, but I did thor­oughly in­spect the model be­fore I took it out to fly. I re­ally like the eas­ily re­mov­able land­ing gear. This model, like many oth­ers, ben­e­fits in ap­pear­ance when the gear is re­tracted. I no­tice no dif­fer­ence in fly­ing qual­i­ties, prob­a­bly be­cause the weight of the gear was neg­li­gi­ble and close to the cen­ter of grav­ity any­way.

The spin­ner is molded plas­tic, soft and glued into place on the prop hub, and there is nothing to true-cen­ter it on the prop. Mine was a lit­tle off, which be­came ap­par­ent the first time I pow­ered up the mo­tor. It didn’t af­fect per­for­mance at all but looked funny run­ning out of round. Af­ter a nose-over land­ing, it re­ally be­came out of round, so I re­moved it af­ter un­suc­cess­fully try­ing to glue it back in place in a cen­tered po­si­tion. I haven’t both­ered to re­place it. While we’re at the propul­sion end of the model, I’ve got to let you know that the scale-look­ing 3-blade prop looks great and also works well with the pro­vided mo­tor and bat­tery, but be care­ful. If you break it, it’s go­ing to set you back about $7 for a re­place­ment.

IN THE AIR

The first flights of my Wild­cat took place at our club site, where we’re for­tu­nate enough to have pre­pared con­crete sur­faces for take­offs and land­ings. I left the model as sup­plied, with the land­ing gear in place (ex­tended po­si­tion). There is a sig­nif­i­cant and vis­i­ble amount of both right and down thrust built into the mo­tor-mount­ing sur­face, and those thrust set­tings do ex­actly what they’re sup­posed to do, es­pe­cially when ap­ply­ing power for that first take­off. I needed no right-rud­der cor­rec­tion af­ter ap­ply­ing power. The model ac­cel­er­ated, its tail came up, and it was air­borne in about 15 feet, climb­ing out smartly. I pre­set the dual rates on aileron, el­e­va­tor, and rud­der to 100% (high) and 70% (low), per the man­ual, and ended up fly­ing it in low rate most of the time. The man­ual pro­vides no rec­om­mended set­ting for the “Expo,” but given the fact that it is a small model, I set it to 75% and it felt just fine. There didn’t seem to be any power-trim change, so I guess the off­sets of the mo­tor I men­tioned ear­lier were right on the but­ton.

GEN­ERAL FLIGHT PER­FOR­MANCE

Sta­bil­ity: All trimmed up, the Wild­cat can prac­ti­cally fly hands-off.

Track­ing: At full throt­tle, it’s pretty fast— vis­ually, a lit­tle too fast. (Had the full-scale

Wild­cat been pro­por­tion­ately this fast, there would have been no need to de­velop the Bearcat!) The AS3X sys­tem works well, cor­rect­ing for gust­ing wind con­di­tions when nec­es­sary.

Aer­o­bat­ics: Most aer­o­batic ma­neu­vers were eas­ily per­formed in­clud­ing loops, rolls, and any typ­i­cal war­bird ma­neu­vers.

Glide and stall per­for­mance: Land­ings are eas­ily done; the model slows down nicely and seems to pre­fer three-point ar­rivals as op­posed to wheel land­ings.

PILOT DEBRIEFING

The nar­row-track land­ing gear makes you tend to avoid long roll­outs and taxi back; re­mem­ber this war­bird only weighs 3.7 ounces, ready to fly. To avoid is­sues taxi­ing, in­clud­ing the “wingtip rash” po­ten­tial, sim­ply re­move the land­ing gear per the in­struc­tions, put the dummy cov­ers in place, and hand-launch it, then land in grass or a smooth dirt sur­face. The Wild­cat looks much bet­ter in the air with­out the gear, any­way. Over­all, the UMX Wild­cat flies and han­dles like a larger model and one with which you can eas­ily be­come com­fort­able.

The bat­tery pack and the mo­tor are easy to get to un­der the re­mov­able cowl.

The scale-look­ing land­ing gear are re­mov­able. You can fly with them in place for ground take­offs or re­move them and hand-launch the Wild­cat.

These open­ings in the belly pro­vide cool­ing for the mo­tor and speed con­trol.

The photo at far left is of the model straight out of the box. At near left, you can see the dif­fer­ence that a lit­tle weath­er­ing makes.

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