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Kappa 35 F5J

Product Code: KAPPA35
 (14 reviews)

Price: $1,051.41 save 15%

Out of stock, notify me when back in stock


The Kappa 35 is probably the best pure F5J plane yet. It is amazingly light, it is a superb design and it is built to a very high standard. The Kappa 35's advanced structural design ensures it is strong enough for its intended mission, and its finish, completeness and attention to detail is outstanding. The model really is almost ready to fly, with all the wing control horns and pushrods ready fitted, so the only work required to finish the wings is to fit the servos. The rudder horn is also fitted, and all the tail pushrod and servo mounting hardware is supplied.

Special features of this model include:

  • A well designed low drag fuselage with a large canopy hatch giving good access to the powertrain and RC, making for easy RC installation and maintenance.
  • A high aspect ratio wing with proprietary airfoils optimised for F5J flying - the wing excels in low speed tight thermal turns, allowing the model to be thermalled away from small, weak thermals with ease. This allows competition winning low starts to be made with confidence.
  • Despite its extremely good thermal performance the wings maintain a good L/D up to higher speeds, allowing the Kappa 35 to return from a long way downwind with ease.
  • The wing has slightly swept back wing tips, making it approximate to the Schulman planform. This is meant to improve performance and handling, especially near the stall.
  • Superb quality of construction and attention to detail. The original MASTER airframe must have entailed literally hundreds of hours work by master builders. Which is fully reflected in the final quality of finish, which we consider second to none.
  • The plane was designed and optimised for electric gliding from the start, it is not a modified F3J design. This has allowed a high aspect ratio to be used and more suitable airfoils.
  • All the control surfaces are sealed and the wing control horns are all hidden inside the control surfaces, further reducing drag.
  • The level of completeness of the airframe is exceptional, allowing the model to be finished in just a few hours.
  • The wing breaks down into three pieces and the tailplane and fin are easily removable, allowing the model to be easily transported to contests.

The model is available in three composite layups:

Light - Mostly glass covered flying surfaces, with carbon local reinforcement and a strong carbon spar. This is the lightest version.

DBox - The flying surfaces have a carbon DBox at the front. The rest is mostly glass with carbon local reinforcement and a strong carbon spar. This version weighs approx 30 g more than the Light version but is stronger. This layup costs approx 7% more.

Spread Carbon - All the flying surfaces are covered in lightweight spread carbon, with extra carbon local reinforcement and a strong carbon spar, resulting in the lightest and strongest model possible. This version only weighs approx the same as the Light version but is much stronger and less susceptible to hanger rash and handling damage. This layup costs approx 24% more.

For all wing layups the fuselage is all carbon. The top of the fuselage is painted and the underside is left in natural carbon black. This looks very attractive. For all electric models (irrespective of the fuselage construction) we recommend the 2.4GHz aerials are exited from the fuselage, so they are in the outside airflow. One horizontal and one vertical aerial usually works well. There is too much electrical equipment in an electric glider fuselage for the RC signal to be reliably received inside the pod.

All models are supplied with high quality sewn cloth padded wing bags, to ensure the wing stays in perfect condition.

Kappa 35 Specifications
Wing span 3.5 m 138 in
Wing area 60.0 dm2 930 sq in
Length inc spinner 158 cm 62 in
Flying weight from 1275 g 45.0 oz
Wing loading 21.3 g/dm2 7.0 oz/sq ft
Aspect ratio 20.4
Wing airfoil Proprietary
EDA (dihedral) 5.0º
Spinner Diameter 38 mm
Centre of Gravity 85-93 mm from wing leading edge
Controls Rudder, elevator, ailerons, flap, throttle

Kappa 35 Light Layup Typical Weights
Fuselage & pushrods 166 g 5.9 oz
Wing centre panel 328 g 11.6 oz
Wing Tips 260 g 9.2 oz
Tail Plane 50 g 1.8 oz
Fin 34 g 1.2 oz
Accessories & glue 12 g 0.4 oz
Total structure 850 g 30.0 oz
Wiring 30 g 1.1 oz
Receiver 12 g 0.4 oz
Rudder servo 10 g 0.4 oz
Elevator servo 10 g 0.4 oz
Wing servos (4) 40 g 1.4 oz
Speed control 45 g 1.6 oz
Motor 120 g 4.2 oz
Prop & spinner 28 g 1.0 oz
Battery 130 g 4.6 oz
Flying weight 1275 g 45.0 oz

Recommended Servos
Elevator & rudder MKS DS6100, MKS HV6100, KST X08, Blue Bird BMS-A10H, Blue Bird BMS-106HV, Blue Bird BMS-107HV
Aileron MKS DS6100, MKS HV6100, MKS HV6110, KST X08, Blue Bird BMS-A10V, Blue Bird BMS-105HV, Blue Bird BMS-106HV
Flap MKS DS6100, MKS HV6100, MKS HV6110, MKS HBL6625 Mini, KST DS135MG, KST X10 Mini, Blue Bird BMS-105HV

The kit comes with CNC cut plywood fuselage servo mounts designed for the MKS DS6100 and HV6100 servos, so it is easiest if these (or the Blue Bird BMS-105, BMS-106, or BMS-107 compatibles) are used for the tail surfaces.

Kappa 35 Control Movements
Rudder 20 mm each way
Flap 85 degrees down
Ailerons 15 mm up, 12 mm down
Elevator 10 mm up, 10 mm down
Recommended camber settings (measured at flap root TE)
Speed mode -1.5° (flat bottom surface)
Cruise mode 0° (flat top surface at hinge)
Thermal mode +2° (2 mm down)

Kappa 35 Powertrain Recommendations
Powerline Micro 1025/F5J 3S 1.3Ah LiPo, 16x8 RF or GM prop (2000 fpm, 43A)
Leomotion L3007-5000 3S 1.3Ah LiPo, 14x8 prop (1750 fpm, 39A)
Leomotion L3013-4550 3S 1.3Ah LiPo, 15x9 prop (2250 fpm, 57A)
Hacker A20-6XL geared 4.4:1 3S 1.3Ah LiPo, 16x9 Aeronaut prop (1950 fpm, 46A)
Mega 16/25/4E direct drive 3S 1.3Ah LiPo, 12x6 prop ( 1800 fpm, 59A)
Mega 16/5/3 Maxon 4.4:1 gearbox, 3S 1.0Ah LiPo, 14x9 prop

Note that although the spinner diameter is 38 mm the width of the canopy hatch is only approx 27 mm, so the max diameter powertrain that can be fitted is 28 mm (with a little flexing of the fuselage skin). Also the RC and flight battery will have to be installed as far forward as possible to achieve a minimum flying weight. Unlike other (converted F3J) models the nose is only just long enough to achieve the correct balance when using a lightweight motor.

Web links
Build photos
RCGroups Kappa 35 thread
Another RCGroups Kappa thread with powertrain info
Kappa 35 Q & A thread

Reviews 14  

 Review by:

Kappa ..... WOW

I received my Kappa 35 a little while back now, and whilst I am a bit of a slow builder, I am very eager to get this beauty in the air. Packaged very well in lots of bubble wrap in a sturdy box. To be honest, I wasn't surprised. A year or two back I bought a Stark Pro DLG from Hyperflight, and it came in the same type of packaging, so it was no surprise ... Hyperflight looks after its customers.
Anyway to the Kappa 35. Wow .... very nice.
My only gripe was that the rudder horn must have rubbed on the horizontal stab (top surface) during transit, as there is a slight dent in the surface. However, very minor and I can fix it myself.
Other than that,.... beautiful plane. Already planning what servos I'd like to use, from Hyperflight of course.
Thank you Neil and team once again, over the many years of amazing service and support.

 Review by:

Kappa 35

what about the kappa 35 ... and although it is a superb discovery for me ... glider f5j different with its small wing surface and its superb lengthening .... it is an extraordinary glider ... I the favorite to my explorer3 ... exellent service from the distributeue ... that happiness

Comment by:

OK, 2015 I had my first Kappa 35 which met with an untimly end, last year I built a Kappa 40, 2018 I put a new Kappa 35 together as a winter project. The thoughts in the back of my mind, how will it compare with the 'Big K40'.

The building process has been covered well enough here so to the flying . . . I had to weight a long time to do any comparisons due to poor weather. Eventualy we got some decent weather, I have been doing a lot of test trimming of bothe aircraft.

The Kappa 35 settled quickly into here trim slot, reminding me very much of that first K35, able to fly the tinyest puff of lift. Penetration into wind is excelent and a turn of speed when required is easily achived. Indeed both the 35 and 40 have similar attributes, although I have found the 35 to be easier to trim to a 'ballance' of my satisfaction. The 40 is not quite the pussycat that the 35 is, it is getting there by using the 35 as a bench mark or refererance to the tiny trim changes that affect performance.

An area both excell in is the landing approach, I only use flaps, no crow required IMHO, although a lot of down elevator mix is used, speed and decent is perfectly controled on a slider with a combination of elevator overriding the elevator mix as required. Aileron/rudder are fully efective with no crow, flap and elevator varies but around 1/3 to 2/3 is normal with a nose pitch down perhaps 10 degrees esaliy controled with the elevator override. The final few meters can require FULL FLAP (about 80 degrees), both K35 and Big K40 almost stop dead, aileron, elevator and rudder control is still fully fuctional with a ballance of flap and elevator for final touch down, no 'donking' required other than the natural dose down pitch.

Thats how it works, if only I was better at that final alignment . . . ?

Kappa 35 is perfectly capable of an easy 10 minutes and a 50 landing in the right hands, Kappa 40 is equaly capable

My conclusion, Kappa 35 as the original design has a finess and togetherness to its handaling that can only be matche by an elite few aiframes, a design that has been missed by many, original in concept with no F3J version, a throughbread indeed. Perhaps the K40 as a modified 35 just lacks that final balance and finess of the 'original' design . . . ? However I am still working on its final 'micro trim' that works well on both models.

A final point, in my opinion, the 'D' box versions have a lot going for them in strength and durabuility, both here are D box, the original 35 I had was all carbon and comparitivly fragile IMYHO.


 Review by:

My third Kappa

This is my third Kappa and second 35 I also have the Kappa 40, ('Big K'). sadly my first Kappa 35 met an early sticky end, my own fault, inexperiance of handaling carbon composite, we learn.

One has been waiting many weeks for some decent weather. Look down the reviews, you will find my original coments on the build,. A little more refine ment perhapps on the part of the manufacures over three years, otherwise all was familiar teritory.

Inbetween times, then and now, I have been flying my 'Big K40', most enjoyable to pilot, no nast habits, the size and proportions present a very nice picture in the air, handaling particlarly well on flat controled landing approches.

This is a review of the 'K35' my sevcond bit at the cherry. I think the fusalarge has been beefed up a little to advantage, nothing has been don about the tail/fin attachment, a 'three handed job' of frustration!

However a minor iritation provided you do not remove the tail fethers every flight session . . .

I took to heart the note in Hyperflights coments re the CG and the nose being only just long enough. On chose the full carbon leyup first off, but experiance has played a part in this number two K35 being the 'D' box leyup. My Big K is a 'D' box layup, she has taken many knock and scrapes with little or no damage. Therefor it seemed logical to go 'D' Box for the new Kappa 35, saves a big chunk on cost over the full carbon offereing. Yet it is strong, feels tough and rigid but with enough give to 'forgive' those dodgy manuvers and landings.

The all up weight RTF as shown by Hyperflight is 1275grs, my original carbon version came in at a tad over 1300grs. The curent Kappa was purchased as a medical theropy to keep my mind active through the winter. I decided to take it on with weight saving as a priority, the carbon 'D Box' ads 30-40grs to the basic glass or all carbon K35.

There is saving weight and saving weight . . . no point in building so light that at the first knock it alls apart. So much thinking and perusing the webb, I came up with verious options based on what one has learned about composite buils, what one likes and dislikes and just how panickity I wanted to be, that takes in dificult non standard building protocols, aproaching a problem from the other side or side ways on.

In Kappa's we have a 38mm nose ring, large by modern standards but very usefull to work with, plenty of room, plus the choice of motr is less restricted. K35 #1 had a Hacker 20 with gearbox, Big K has a Glider Drive direct . . . Kappa 35 #2 . . . moves away from powerrtrain convention and uses a 35/30 size motor, bolted from the back onto an aluminum CNC firewall which is screw atached from the side, remove the 4 screws and the motor/firewall assembly is easily removed. This arangment alows for a light'sh motor (88grs) to be used moves the eight forward considerably making the CG very easy to achive with out any lead. It also has a big offering in keeping the RTF weight to only 1275grs.

So flying today, almost no wind, light cloud and very warm, shirtsleves weather. Making all checks over and over, geting a friend to double check. Friend hand launched for me, its a good idea to have both hands on the TX.

Absolutly perfect, no trim changes wer require in the climb away, a non evenrt realy. So fly around get a feel one or two clicks on the elevator. Land check all is still tight, new battery and a second launch, this time by myself . . . . !!***!! . . . half throttle and the model was literaly wrenched from my hand!

I had got te motor setup absolutly spot on, half throttle or less for the hand launch, then more power as one would battle a wind, with a reserve of power if required to reach a point or extra hight.

After 4 batteries, = 3 power ups we called it a day, discussed the events of the day. The power launch was very unexpected, reserves of power could be usefull in certain competition situations. The light weight and very clean lines gave Kappa 35 a flying speed that I have rarly seen and yet reaction to control inputs is shown with no real vices, this has got to be an on going, work in progress for fine tune of the final trim.

It would habeen nice to have compared the Big K directly with the K35, gor so enthrauled that when we looked it was time to pack up.

'Kappa' gets my vote . . . Cj

 Review by:


I am still enjoying the Kappa.

Its done a lot of flying since July 2015. Its had a couple of incidents, caught a tree and landed nose on plus another time got blown into a fence, but damage has been minimal, cosmetic wing repairs only. Fuselage and tail are still like new. Tough model despite the low weight.

Last month it won the biggest F5J event in Australia in a mixture of conditions against a lot of good flyers with models from Ultimas, Maxas, Storks, Explorers, Avas, Pulsars etc including some ultra light specials.

Its still 1300g and I never add ballast. I also do not use camber changing, I think the airfoil works best in neutral with plenty of speed range with simple elevator trim adjustments. CoG is at way back almost 50% of root chord, seems to work because of the swept back tips.

Great model

 Review by:

Kappa 35

The Kappa 35 is a great plane for the money. The LDS system for flaps and ailerons cuts build time considerably !

 Review by:

First I'd like to warn you that the fuselage will crack if you land as heavily as those stronger gliders like Xplorers. The damage was easily repaired and the plane didn't get much extra weight.

I didn't have glider competition experience and I went to national contest after 3 hours of test flights with Kappa. In the middle of the day I won 1 round where only 2 of 11 glider flew the whole 10 minutes. When the wind speed raised a bit I lost a little bit confidence because my plane doesn't have ballast and weights 1420 g. My CoG was quite in a middle 90 mm. I've pulled it to 93 mm and it still isn't tail heavy when flying in strong thermal. Does anyone have CoG more back?

I decided to make tail links with simple l-bend (rudder) and z-bend (elevator). I takes some manouvers to assemble that on field but I'm already used to it.

I've all servos DS6100 but my opinion is that flaps needs something stronger when you can't have that bearing of "servo rahmen" in limited space. I think KST DS135 will survive better. The moment arm of that flap mechanism is demanding for the servo forces.

Last sunday I had good change to thermal in low altitude while the lift was relatively strong, windy and narrow. With active use of rudder Kappa was climbing nicely. I used flat wing without positive flaps. There was enough power in the ailerons even when there is now mixing with the flaps.

I'm totally happy to fly with Kappa35 and waiting to test how some ballast would affect on performance.

Comment by:

very nice gilder

Nice finish, very light, but need som time to get RTF.
Miss some space for ballast / weight as isīt always windy in Denmark.

 Review by:

Kappa 35

This is one fine aeroplane. It is capable in more wind than I expected.

Assembly was straight forward, although care is necessary to ensure slop free servo set up in the wings. I used balsa wedges to best locate the push rods to prevent them moving in and out in the servo arm holes.

Finish on the carbon D box section on the wing tips is disappointing, with roughness where the fabric weave is partially proud. Some paint has come away from the wing tip when joining tape is removed.

Gripes aside, I am delighted with the plane, and give it 5 Stars on its performance!

 Review by:

First flights

It arrived last week and I had it ready to fly in less than two days. Quality is amazing, all the fits are perfect. The biggest tasks are making the wiring harness, and programing the Tx.
It needs 8mm servos for the wing as someone said, and the horns have to be very short too, so the servos need to be good accurate ones.
I used a 28x26 out runner which is light so to get the CoG correct it needed a 3s1900 battery. There is only just enough space left for an F5J logger.
Weight is 1300g.
Weather cleared for flying today. It went up like on rails and just floated about. The three camber settings as specified give noticable speed range. Flaps and crow bring it down steep but well under control. After a few mixer adjustments I had a few more flights and some big thermal climb outs. Being light it shows you the slightest lift and can turn amazingly small circles.
Build tips: Trim the ply R&E servo frame down so the RX can be slid in behind the servos, while fitting the frame as far aft as possible. There is only just enough space in front of them to get any battery in through the hatch.
Looking forward to F5J event next week.
Phil S in Sydney

 Review by:

Just a quick few, lines to report that I have now flown the Kappa 35 I bought from HyperFlight a few months ago. I had sold my much loved AVA during the Kappa construction and was becoming anxious that the Kappa might not reach my expectations.

I need not have worried! It is an extraordinary glider. The combination of high performance with incredibly docile handling is quite remarkable. When I have a little more time I will write a fuller review, meanwhile many thanks for taking my money and replacing it with the best glider I have ever flown!!

Comment by:

Fly like a bird . . .

We have been waiting for some good weather to maiden flight Kappa. I have checked and double checked everything I could. I changed horses on the power-train during this checking, originally opting for a hi-speed 28mm direct drive out runner. Swapping at the at the last minute after some advise to a Hacker A20-6XL.

I have been on the field today in perfect trimming weather, sun, a bit of cloud and about 6mph from the west, a good direction for our field. Cup of tea, a chat, all glider pilots at the field in the week, they have been waiting patiently for Kappa to maiden.

Cant put it off any longer, Brian gave me a perfect launch, Kappa went away like she had been trimmed and sorted weeks ago. A bit of a non event really, no trim required apart from a few notches on the elevator. I had set the CG at the most forward recommended.

The Hacker motor, 4s, 1000mah 40c battery and 13x8 prop had Kappa climbing like a home sick angel. The setup can handle up to a 13x11, as I was only using a 50ah ESC the smaller pitch seemed appropriate as the watt meter indicated.

As I say the launch was uneventful, it was the flying ability of Kappa that took us all by surprise. That 'first trimming flight' on the one power up to about 100m lasted 15 minutes plus, I was not trying!

Flying Kappa is like choreographing a ballet, turns are flat and graceful. I had not mixed any rudder with the ailerons, I dont think she needs it although very tight thermal turns can be done if you include some rudder. Speed had a wide range.

How can I describe it, she is a very well behaved througbread, no vices that I could find during the 3 flights. The transmitter was handed round, all agreed "she is a very fine swan indeed".

OK so here we are, 15 minutes into the first flight, all had had a stir of the sticks, time to land . . . Absolutely priceless, as good as she is in staying in the air, she matches it with aplomb on her landings. A straight forward flap/linked elevator approach, total control, no vices and a 40 pointer as well, all three landings were equally good with the last, 50 points!

I will be working on the final trim, but it looks like my task will be an easy one?

Total thumbs up from me . . . she flies like a bird.

Comment by:

'A second bite at the cherry'

. . . Having sat back and relaxed after what was a very intense 6 weeks of single minded thought and assembly of Kappa. I can now sit back, relax and appreciate a few of the finer points of this 'very special' e-glider.

Just how clean the lines are can be seen in the heading picture, the fuselage is nothing more than a pencil.

The wings are 20:1 aspect ratio, tail and fin are of very fine proportions. The fin incidentally is the same size and plan-form as half the tail.

There are no push rods, horns, lumps or bumps on any of the flying surfaces. In fact there are no lumps or bumps anywhere save a very well faired and disguised blister on the nose to accommodate outrunner motor power wires. Super clean surfaces with all hing lines sealed

A close look at the unspecified wing section reminds me of that seen on modern full size gliders with their heavily under cambered forms?

All of which makes me think that Kappa has been thought of along full size lines?

The front fire wall is molded in as part of the fuselage, (smooth) carbon back and front of a ply former. You wont knock that out on landing.

These clean lines make me wonder how much wind her 46ozs can cope with? Again looking at full size practice of carrying ballast for speed/penetration.

I have been doing some experimenting with ballast in the past 18 months. A friend has also tried it recently, we both have found that there seems to be a sweet spot, too much and you are flying a, 'house brick with wings', to little and the model just does not fly right, but get it right, and the results give an amazingly wide speed range using the same amount of ballast.

Hence my note in the review, that I have made provision for 'ballast adjustment' on the CG on my Kappa.

So its going to be interesting in the 2015 season just where Kappa is going to feature in the UK honors list. Will it break the hold of the other front running gliders?

 Review by:

A through bread machine . . .

Kappa has been a long time coming, it was a year ago Neil suggest 'watch this space'. Early December 2014 saw the large box in my living-room, carefully unpacked, I pawed over the contents. Kappa is special, she feels different to anything I have had in the past. Pick up the fuselage which is in one piece, it weighs nothing, a beautiful carbon fiber molding that feels thin and yet so rigid. Wings, tail, all had this quality 'attention to detail' air about them.

At first glance after the initial 'wow' inspection, Kappa looks like a straight forward assembly/radio installation job, which it is, but as she is such a through bread, the assembly is thought provoking. Simplicity, basic flattened brass tube is used for elevator and rudder horns, this coupled with the ingenuity of the totally hidden flap and aileron horns. There are is nothing sticking out in the airflow and all hinges are sealed,

Essentially, the fuselage is a 40mm tube that tapers from the wing back. The spinner diameter of 38mm and a blister to accommodate motor cables encourages one to think 35mm direct drive. Unfortunately the cockpit opening is only 27mm at it widest point. I spent almost the whole of December puzzling over how to get a quart into a pint pot?

Various ideas but the issue of weight always reared its ugly head. I eventually found a 28mm direct drive motor that could deliver enough power (by my pocket rocket standards) to go with.

Personal, I feel Kappa could have had a longer canopy or at least re positioned, it is impossible to get into the front without long tools that I had to devise . . . we overcame.

I cut a large hole in the fuselage wing seat, for two reasons, I wanted to mount the servos under the front of the wing and also to give room to ad ballast??? . . it also makes getting at the wiring loom so much easier. I worried that fuselage rigidity might be compromised, not a bit of it, no problem at all.

The rudder and elevator are connected to the servos by 0.8mm piano wire running in semi rigid outers, these are over a meter long. The wire was poor quality, being rough, I spent much time smoothing these out. In moving the servos I used a conventional servo tray rather than the multi piece unit supplied, saving a good few grams.

The wing is a pleasure to look at, but working on it, that is a different story. The preinstalled push rods and hidden horns make the geometry critical, achieving free movement on the ailerons requires much work and dry fitting. I used recommended 6100 servos,10mm thick, a mistake, go for 8mm servos on the ailerons, it would make things so much easier . . . hind sight is a wonderful thing.

So the only job to do was to build the wiring loom, not my favorite job but using Hyperflight light weight servo wire and a Multiplex multi plug, I did a fair job, even if I do say it myself.

Screwing the tail on needs 'three hands' but it was done. I was disappointed in a red airplane with a rather dull maroon color on the top surface and fin, not a deal breaker, perhaps red pigment is heavy.

CG required a little lead, due to the extra light motor, final weight came in at 1302gr, as my Kappa is the stronger 'spread carbon ' version, I think that is job don.

Not difficult to build but not for the inexperienced, comes with wing bags, nice touch. Over all I am happy with what I got for my money, this feeling got stronger as one handled a became closely acquainted with Kappa and her finer points.

Now we wait for a flying weather window, watch this space.

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