Flight test: Spacek SD-1 Min­is­port

Whether you build it or buy it ready to fly, this Czech de­signed SSDR will put a big grin on your face

Pilot - - CONTENTS - Words Dave Un­win Pho­tos Keith Wil­son

Fun and af­ford­able, this sporty sin­gle-seater can be fac­tory or home­built

Hav­ing strapped on the SD-1 (well, that’s what it feels like) I ges­tured at the fuel sight tube: “Looks like around twenty litres Jiri, so how much play­time do I have−about an hour and a half?” “Ap­prox­i­mately four hours,” he replied with a grin. Now, I’d sub­con­sciously in­cluded the thirty min­utes ‘day VFR’ re­serve in my guessti­ma­tion, but still…

As some sec­tors of UK gen­eral avi­a­tion seem de­ter­mined to price them­selves out of ex­is­tence, it’s al­ways re­fresh­ing to dis­cover a new, fun type that is also gen­uinely af­ford­able. Hav­ing flown sev­eral in­ter­est­ing sin­gle-seaters (and be­ing the owner of a Jodel D.9) the smart lit­tle SD-1 re­ally caught my eye at the 2017 LAA Rally at Sy­well. Once I learned a brand­new ex­am­ple could be ‘flown away’ for around £22,000, I wasted no time in set­ting up a flight test−and UK agent Jiri Kra­jca oblig­ingly flew it to Fen­land one af­ter­noon last month.

As it tax­ied across the grass the SD-1 looked a lit­tle rem­i­nis­cent of the MiniMax, prob­a­bly be­cause of the canopy, al­though it is ac­tu­ally a clean-sheet de­sign from Igor Spacek, and in­tended to meet SSDR rules whilst also be­ing com­pet­i­tively priced and−of course−fun to fly! My ini­tial thoughts are that the build qual­ity is very good; even close-up the wing and fuse­lage are so smoothly fin­ished they look like they are made from com­pos­ite (but are ac­tu­ally ply skinned). Al­though a rel­a­tively sim­ple air­craft to build and fly, the SD-1 is not the eas­i­est to write about, as it is avail­able with three dif­fer­ent un­der­car­riage ar­range­ments, five dif­fer­ent en­gines, and even an en­larged fuse­lage. Con­se­quently, this re­port will fo­cus on the ac­tual air­craft tested, G-CJLU. Start­ing at the spin­ner, the pro­pel­ler is a Helix H30F two-blade com­pos­ite unit, which is spun by a closely-cowled SE-33 air-cooled V-twin. This 820cc en­gine is based on a Briggs & Strat­ton de­sign usu­ally found in in­dus­trial ap­pli­ca­tions. It pro­duces 33hp at 3,600rpm, weighs a cred­itable 32kg, and is fed from a 35 litre fi­bre­glass-pvc foam sand­wich tank, lo­cated im­me­di­ately aft of the fire­wall. Unusu­ally, each cylin­der has its own mag­neto, while the twelve-volt elec­tri­cal sys­tem uses a light­weight lithium-ion bat­tery charged by an al­ter­na­tor. The fixed tri­cy­cle un­der­car­riage fea­tures a cas­tor­ing

nose­wheel fit­ted with a fric­tion damper, while the 300x100 main wheels fea­ture ca­ble-ac­tu­ated drum brakes and are car­ried by pul­truded fi­bre­glass legs. All three wheels are closely spat­ted.

The main­plane is a two-piece unit, and Jiri tells me that it can be eas­ily de-rigged by one per­son in around five min­utes. One of the rea­sons it can be done with­out help is that, at only twelve kilo­grammes, each wing is in­cred­i­bly light. The wing uses a GA 37U-A315 aero­foil sec­tion and con­sists of a com­pos­ite main spar with car­bon caps, which car­ries ribs made of ex­truded poly­styrene, glued in place and cov­ered

The main­plane is a two-piece unit... de­rigged by one per­son in around five min­utes

with 1mm-thick ply­wood. The up­turned wingtips are en­tirely com­pos­ite. Al­most the en­tire trail­ing edge of each wing con­sists of full-span flap­er­ons which have three set­tings: ‘Up’, ‘T/O’ (7°) and ‘Land’ (20°).

The truss-type wooden fuse­lage is cov­ered with ply­wood vary­ing be­tween 0.8 to 3mm thick­ness and has a Galaxy GRS

4/240 bal­lis­tic (parachute) re­cov­ery sys­tem at­tached to the fuse­lage bulk­head be­hind the cock­pit, with the front straps at­tached to the up­per en­gine mount. The BRS is op­tional and this space can also be used for bag­gage if you choose not to have the ’chute. The bag­gage bay is be­hind the raked seat back and can carry up to a max­i­mum of ten kilo­grammes. The ac­tual amount varies ac­cord­ing to the pi­lot’s weight and fuel quan­tity. I’m not thin and, with no bag­gage, can fill the tank com­pletely, but with max­i­mum bag­gage I’d be re­stricted to 21 litres (which, you may re­call, is still around four hours, no re­serve).

The all-fly­ing tail or sta­bi­la­tor is stat­i­cally bal­anced and fea­tures a large anti-servo tab. Its con­struc­tion (and also the fin and rud­der) is es­sen­tially the same as the wings−a com­pos­ite spar with car­bon caps, poly­styrene ribs and ply­wood skin. The flap­er­ons and sta­bi­la­tor are ac­tu­ated by a com­bi­na­tion of pushrods and bell­cranks, with the mixer for the flap­er­ons un­der the seat. Ca­bles ac­tu­ate the rud­der, while springs (also un­der the seat) are used for pitch trim.

As I ex­am­ine the air­craft more thor­oughly, Jiri con­firms the salient facts and fig­ures. It has an empty weight of 130kg and a max­i­mum all-up weight of 240, which pro­vides a 110kg use­ful load. It is 4.35m long, 1.23m tall, with a wing­span of 11.1m, and has a power load­ing of 9.60kg/kw and a wing load­ing of 39.34kg/sq m. It stalls at 34 knots, has a Vne of 119 and can cruise at 85kt while burn­ing un­der five litres per hour.

As is usual for small sin­gle-seaters, get­ting in re­quires a bit of a knack. The com­pos­ite canopy is hinged to star­board and fea­tures a NACA in­let for ven­ti­la­tion. Hav­ing wrig­gled into po­si­tion (the seat is fixed but the ped­als ad­just) I ex­am­ine the in­stru­ments and con­trols. One of the great things about an SSDR is that you can fit as many−or as few−in­stru­ments as you want. Lima Uni­form’s is an ob­ject les­son in dig­i­tal min­i­mal­ism: the ‘glass panel’

diplays are an ipad and a back-up iphone, with en­gine mon­i­tor­ing han­dled by an MGL Stratomas­ter In­finiti E3−and that’s it! The ipad and iphone are con­nected to the pitot/static sys­tem via a Ta­los Ae­o­lusSense 3A, which re­ceives dy­namic and static pres­sure in­for­ma­tion, con­verts it into a dig­i­tal for­mat and sends it via Wi-fi to the ipad and iphone, al­low­ing air­speed, al­ti­tude, and ver­ti­cal speed to be dis­played in which­ever units you pre­fer. (If you’re not an Ap­ple fan, Ta­los also works on the

You can fit as many — or as few — in­stru­ments as you want

An­droid op­er­at­ing sys­tem.) A mov­ing map, com­pass head­ing, OAT, TAS etc can also be dis­played. The Stratomas­ter E3 is a very ca­pa­ble lit­tle unit that can dis­play (and record) a plethora of pa­ram­e­ters. On the test air­craft, it showed both CHTS, rpm and oil tem­per­a­ture, with the sta­tus of the oil pres­sure only shown by a red LED warn­ing above the MGL en­gine mon­i­tor. A red light set into the Stratomas­ter il­lu­mi­nates when­ever any of the pre-set max/min val­ues are ex­ceeded.

Per­son­ally, I’d also put the oil pres­sure through the Stratomas­ter, as it is one of the best in­di­ca­tors of an en­gine’s health. Apart from the big red ‘Start’ but­ton

(which seemed un­nec­es­sar­ily large, al­though it does also hold the bracket for the ICOM trans­ceiver), all the elec­tri­cal switches are in a neat row on the far left of the panel, and con­sist of a guarded ‘Mag’ switch (it se­lects both mag­ne­tos), bat­tery mas­ter, Ta­los and fuel pump, with the rel­e­vant fuse above each switch. An anom­aly is the switch for the elec­tric oil pump. Al­though in­creas­ingly com­mon on large pis­ton-pow­ered war­birds (the last air­craft that I flew fit­ted with one was a Mer­lin-pow­ered Mus­tang) it seemed some­what out of place in an 820cc vee-twin. Jiri ex­plained that pre-oil­ing is sim­ply a way to re­duce wear by rais­ing the oil pres­sure be­fore start-up, par­tic­u­larly if the en­gine hasn’t run for a while. Once the en­gine is run­ning the me­chan­i­cal oil pump takes over. The port cock­pit side­wall car­ries the throt­tle, choke and el­e­va­tor trim, with the flap lever and BRS han­dle on the op­po­site side. Per­son­ally, I’d pre­fer the flap lever to be on the same side as the throt­tle, but was pleased to see the choke well sep­a­rated from the throt­tle. There is no carb heat.

One thing I didn’t like was the fuel sight tube. Not only would a bit of wire pok­ing out of the filler cap and at­tached to a float be per­fectly ad­e­quate, but the cur­rent ar­range­ment must make re­mov­ing the panel more com­pli­cated than it needs to be. Fi­nally, a sim­ple slip ball was no­tice­able by its ab­sence, (it can be shown on the ipad)−but one of the joys of kit­planes is that the panel can be truly be­spoke.

Clos­ing the canopy gen­er­ated my usual grum­ble about the lack of a di­rect vi­sion panel, (in fact, what this thing re­ally needs is a slid­ing bub­ble canopy) and, with the big vee-twin rum­bling away, I fol­lowed the C172 cam­era­ship out to­wards Fen­land’s Run­way 08. Even though I was taxy­ing on grass in quite a light wind, reg­u­lar ap­pli­ca­tion of the pow­er­ful rud­der was re­quired, along with an oc­ca­sional jab of heel brake, which made me think that the nose­wheel fric­tion damper needed tight­en­ing. In fact, a long cross­wind taxi on tar­mac would ne­ces­si­tate fre­quent use of the down­wind brake, and if the air­craft was to be based on a hard­sur­face air­field I’d rec­om­mend some sort of nose­wheel lock. The field of view while taxy­ing is good, al­though I did won­der if per­haps the bulged top cowl­ing would be in­tru­sive on the tail­drag­ger vari­ant.

I’ve never re­ally thought of a Cessna 172 as gen­er­at­ing wake tur­bu­lence be­fore, but as it starts its take­off roll and I taxi into po­si­tion it sud­denly oc­curs to me that wake tur­bu­lence is rel­a­tive, and the ma­chine I’m in is less than 25% of the mass of a 172! Con­se­quently I give the Cessna a head start, and also po­si­tion on the up­wind side of the run­way. Jiri has recommende­d us­ing a soft-field tech­nique with take­off flap, so I slowly open the throt­tle with the stick on the back­stop, and then just ease it for­ward as the el­e­va­tor starts to bite, the aim be­ing to hold the nose­wheel just clear of the ground. The am­bi­ent con­di­tions are close to ISA (Fen­land is only six feet above sea level) with a gen­tle north-east­erly, and that, and the pro­pel­ler’s di­rec­tion of ro­ta­tion, gen­er­ate a slight swing to port as the

nose­wheel lifts off, which is eas­ily cor­rected with a small dab of rud­der.

The SD-1 skips into the sky in the first third of the run­way and ac­cel­er­ates nicely, but a po­ten­tial ‘gotcha’ at this junc­ture is the low flap lim­it­ing speed, so I quickly change hands, whip the flap up and set off after the 172, with plenty of geo­met­ric cut-off for a quick join up. All three pri­mary con­trols feel crisp, taut and pow­er­ful, the field of view is fine and within min­utes I’m slid­ing into a close ech­e­lon port. Dur­ing the brief­ing pho­tog­ra­pher Keith had re­minded me that the SD-1’S diminu­tive size meant I’d have to get closer than usual−so I do. Fen­land’s cheery CFI Steve Brown does an ex­cel­lent job of chas­ing the lim­ited amount of sun­light around, and we soon have the shoot in the can, al­though on the first ‘break’ the spritely roll-rate only al­lows Keith to take two pic­tures, in­stead of the dozen or so he usu­ally gets. Suit­ably chas­tened, I break con­sid­er­ably more slowly the sec­ond time.

Leav­ing the 172 to re­turn to Fen­land I get on with the rest of the test, start­ing with a more in-depth eval­u­a­tion of the gen­eral han­dling and stick-free sta­bil­ity. The han­dling re­ally is very good, with plenty of con­trol au­thor­ity around all three axes and no dis­cernible break­out forces. My tests of sta­bil­ity re­veal it to be pos­i­tive di­rec­tion­ally, neu­tral lat­er­ally and just barely pos­i­tive lon­gi­tu­di­nally. In fact, hav­ing pitched up to lose ten knots from a com­fort­able eighty-knot cruise and then re­leased the stick, I won­der for a cou­ple of sec­onds if the SD-1 is ac­tu­ally di­ver­gent in pitch, as the ground be­gins to loom through the wind­screen. Any­way, just about the time I fig­ure that as the air­speed is still in­creas­ing, per­haps I’d bet­ter in­ter­vene, the nose slowly rises and after sev­eral high am­pli­tude short wave­length phugoids it re­luc­tantly re­turns to the trimmed speed. Of course, the SD-1 re­ally is quite short-cou­pled, and the slightly ‘soft’ lon­gi­tu­di­nal sta­bil­ity is prob­a­bly ex­ac­er­bated by the all-fly­ing tail.

Mov­ing on for a look at the cruise, the SD-1 is par­tic­u­larly im­pres­sive. At around 3,000rpm (to be hon­est this was dif­fi­cult to judge, as the in­di­cated rpm fluc­tu­ates due to RF) the IAS is a com­fort­able 80kt at 3,500ft, giv­ing a true air speed of 87 and a fuel flow of less than five litres per hour. Those of you who are par­tic­u­larly adept at con­vert­ing nau­ti­cal miles to statute miles, and litres to gal­lons have prob­a­bly just reached the same con­clu­sion I did while writ­ing up my notes−that’s about 100 air miles per gal­lon!

Slow­ing down for a look at the stall takes a while. It’s a slip­pery lit­tle beast,

80kt IAS at 3,500ft... fuel flow less than five litres per hour

and the low Vfe (56kt) doesn’t help. For the first stall I leave the flaps up, and at around 45 it starts to ‘mush’ earth­wards with an in­creas­ing sink rate, while a de­par­ture stall with take­off flap and power is also quite in­nocu­ous. How­ever, the full flap stall is a lit­tle dis­con­cert­ing−not for how the air­craft be­haves, but for how it feels. Ba­si­cally, the prob­lem with flap­er­ons is that there is a def­i­nite degra­da­tion in roll au­thor­ity at slow speeds. As the IAS drops be­low 45, lat­eral con­trol di­min­ishes ex­po­nen­tially−and as I’d left a lit­tle power on to see how slow it would go, by the time the speed gets down to be­low 35 it feels as if the metal rods that con­nect the stick to the flap­er­ons have been re­placed by el­derly rub­ber bands!

I must em­pha­sise here that this was a flight test, and that there re­ally isn’t any rea­son why most SD-1 own­ers should have to ven­ture any­where near this par­tic­u­lar cor­ner of the envelope. Fur­ther­more, an­other rea­son for the un­set­tling feel­ing is that above 70kt the han­dling is so taut and crisp that when you do let it get very slow it’s a “hmmm, has some­thing be­come dis­con­nected?” mo­ment. An early-model Kit­fox feels very sim­i­lar. It’s cer­tainly not an ex­er­cise I’d rec­om­mend on a bumpy day, and once the nose does even­tu­ally drop you’ve got to be care­ful not to ex­ceed Vfe. My ad­vice? Keep the speed above 45kt un­til you’re ready to flare.

Back in the cir­cuit I take care to en­sure the speed is be­low sixty, and also ap­ply plenty of nose-up trim be­fore lowering the first stage of flap. In cross­winds or tur­bu­lence, the POH rec­om­mends only us­ing the first stage of flap, and keep­ing the speed around 55. For pi­lots con­vert­ing onto the SD-1 from more tra­di­tional types such as Cess­nas and Pipers, it can­not be em­pha­sised enough that the time­honoured for­mula of us­ing 1.3 x Vs1 on the ap­proach sim­ply doesn’t work, and that Vs1 x 1.5 or even 1.6 is much more ap­pro­pri­ate. Un­for­tu­nately, even on a calm day when fifty is ap­pro­pri­ate, you’re only seven knots be­low Vfe, so the speed must be mon­i­tored care­fully and the flaps re­tracted promptly in the event of a missed ap­proach. The field of view all round is ex­cel­lent and the SD-1 slides down to­wards the run­way as if on rails. As is of­ten the case my first land­ing is em­i­nently sat­is­fy­ing, so with plenty of run­way re­main­ing it’s full power, change hands− flaps to T/O, change hands, ro­tate, change hands, flaps up, change hands… and now you know why I’d rather have the flap lever on the left.

Half­way along the down­wind leg and the SD-1 is about to give me my sec­ond

“hmmm” mo­ment. I de­cide to try a glide ap­proach so, abeam the num­bers, slowly pull the throt­tle right back to the stop. Jiri had told me that the en­gine was a lit­tle ‘lumpy’ at flight idle, and in­deed it is. If you’ve ever rid­den a 1970’s Moto Guzzi 850 T3 you’ll know what I mean, and ini­tially it is vaguely un­set­tling.

Any­way, hav­ing turned in slightly too early, slipped off a load of height on base (in­ci­den­tally, it slips nicely) and rolled out onto fi­nal, I re­alise I’ve slipped off a bit too much height and de­cide to add a pinch of power. The throt­tle def­i­nitely moves un­der my hand, but the en­gine doesn’t pick up. Slightly per­turbed, I move the throt­tle a lit­tle bit more−still nothing. By now I’m be­gin­ning to think that the en­gine has stopped and the prop’s just wind­milling, but a proper shove on the throt­tle pro­duces a healthy burst of power promptly putting the SD-1 back on the glides­lope. It would seem that the first three cen­time­tres of an­gu­lar move­ment through the throt­tle quad­rant doesn’t do much. After an­other smooth land­ing, I re­tract the flaps fully dur­ing the touch-and-go and can’t re­ally dis­cern that much dif­fer­ence in the take­off per­for­mance.

I could’ve cheer­fully spent all af­ter­noon per­form­ing touch-and-goes on Fen­land’s de­light­ful grass run­ways but, with some re­luc­tance, con­clude that per­haps I’d bet­ter let Jiri get home in the day­light, as Lima Uni­form doesn’t have lights. For the fi­nal land­ing, I de­lib­er­ately land slightly long, com­pletely ig­nore the brakes and still have to add power to turn onto the taxi­way that par­al­lels 36/18. You don’t need much run­way with an SD-1.

A 21st Cen­tury Jodel D.9

I re­ally was rather taken with the Min­is­port, which could well be de­scribed as a ‘21st Cen­tury D.9’, and would love to own one. I’d prob­a­bly go ‘old school’ and have an open cock­pit (if pos­si­ble), tail­wheel un­der­car­riage and ana­logue in­stru­ments−but I’d en­joy the SD-1’S elec­tric starter!

Power comes from a 820cc air­cooled V twin — bik­ers will un­der­stand the Moto Guzzi ref­er­ence

The get-out clause: a BRS parachute is an op­tion (al­ter­na­tively you can make this an ad­di­tional bag­gage bay)

Sim­ple tri­cy­cle un­der­car­riage fea­tures a GRP bow. The air­craft can also be con­fig­ured as a tail­drag­ger

Op­er­ated by pushrod, the sta­bi­la­tor (all-mov­ing tailplane) is fit­ted with a large anti-servo tab

‘Get­ting in re­quires a bit of a knack’ — but Dave looks com­fort­ably en­sconced here. A bulged canopy is avail­able to suit taller pi­lots

To the right of the re­clined seat are the flap lever and BRS pull han­dle...

...and to the left are the trim­mer (green knob) and throt­tle

Glass cock­pit, SSDR style: ipad and iphone do­ing the hon­ours. One or two hu­mor­ous touches raise a smile — do you re­ally need that huge fancy car starter but­ton?

We do pre­fer me­chan­i­cal trim sys­tems like the neat one fit­ted to the SD-1

Full-span flap­er­ons make for sprightly han­dling at speed but give mushy lat­eral con­trol near the stall with flaps down

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.