Rotax 583 powered KR2

[Henni]

Hi all,

This is where I stand after today. How's that for a spacious KR2 cockpit? Just look at the leg space. Look at the space left next to me for the passenger. This cockpit will be rather roomy - by KR2 standards that is. Aaaahhhh!!! I do not need to alter the firewall any more. I'll move the rudder pedals more forward & that will suffice. Also, to my utmost surprize, the previous builder already build a wingwalk area into the left inner stub wing. I can stand on it on one leg only with all my weight on it. It is rather strong. So this is another bonus for me.

Finally I fit with ease. And so will Monica. Everything is starting to come together. My arm will be in that position with the canopy closed. The instrument panel will fit to the front of the remaining turtle deck. No need for a centre console any longer. The canopy won't be all that much wider. it'll start at the original existing fuselage position at the front & rear turtle decks & widen to the outside of my arm in the middle only.

Within the next week or so I can maybe at last start with the canopy. I'm looking forward to that as after all this is REALLY what it's all about! I'll start off by widening the window sills where our arms would rest with ply. Then I'll blend that on both sides into the very bottom part of the fuselage also with very thin ply. Once that's done, I'll start with the upper canopy frame & eventually adding the lexan windows.

Wow, but this aircraft is built very, very light. The part of the forward turtle deck that I cut away weighs almost nothing. The previous builder can sure work with wood & I get more and more respect for the deceased man.

Please note that the stall speed I'm aiming for is with one up. I have no idea what it would be with a passenger and full fuel. Maybe closer to 50mph or so. I'm not that unrealistic & I'll try my utmost best to get her stall speed down to 40mph or less in a light configuration.

Keep well all,

Henni

[Henni]

Hi everyone,

Does anyone perhaps have a link available of any more detail on how to make these:

http://www.love4aviation.com/DYNAERO/Te ... +2003.html

I can come up with a rough idea, but I'm sure there is a better way. How is the forward airfoil of the flap made & how is it attached to the rear section? (thinking wood, foam & F/glass, that is)

Yes, I'm aware of the serious trim changes caused by these, however I'm still interested in giving it some more thought. The Black Shape aircraft uses the same, and so do many other designs like i.e the Pilatus PC6.

Keep well all,

Henni

[Henni]

Hi all,

Completely finished the second seat today. I HAD to get our SsangYong going this weekend. I just put the spanners down & took her for a test drive a while ago. I'm so happy that everything is back to normal again. That single task sure kept me occupied for quite a while.

As soon as I've done something interesting again, I'll post some more pics. In the meantime, I have decided to go for the slotted flaps as per my request above. Just see what the runway looks like on finals with those deployed! Would be rather interesting once I start making it...

Rudi, thank you so much for the kind words the other day - highly appreciated my friend!

Keep well all,

Henni

[Henni]

Hi all,

I've been rather quiet for a day or two. However, things are in the works for a possible better engine & the choice I make in this regard will effect EVERYTHING that I do onwards from here. Except for a few simple tasks, I simply HAVE to wait for the outcome before I can proceed. It's all about the total weight in the nose...

Hopefully I'll know & make the best choice in my own interest within a week or so & then I'll continue in all earnest again. In the meantime a few more pics of how I intend to modify the flaps, only in my case it will be the double slotted Fowler type as on the MCR4S. I would be a fool not to add those to an otherwise already highly modified project. Might as well go for the max I could achieve. My ailerons are already huge and inboard only, so I am in the ideal situation to use this to my advantage.

I definitely don't want another KR2 that floats forever during landings...

I put 1130 hours on N56ML and did over 2800 landings, most of them at the absolutely bottom of the speed envelope, putting it very close to the end of the runway (and occasionally a little short of it) so I could stop it ASAP...and that's using barn-door flaps! And yes, I usually slipped it fully all the way down with my huge rudder, and straightened it out maybe a second or two before touchdown. I'm familiar with that, but I still used my flaps almost EVERY landing. The few times I didn't use them (just to stay proficient), I felt like I was landing downwind!

I'm almost finished putting a 1/4" thick speed brake on the belly of N891JF, and the total installation, including actuator, will weigh a little more than three pounds. That's a trade I'll take.

The point of flaps is to both provide more lift, yielding a slower landing speed, and drag, to help you slow it down on descent and while landing. A belly board doesn't give you the lift, but the drag is vital during landing, especially during ground effect, not to mention improved visibility over the nose, which improves safety. Almost everybody who has flaps or a belly board loves them. But if you don't want to trouble yourself with that compromise, nobody will beat you up for it...

Mark Langford

...however the landing are a challenge it floats a lot more than mine and it seems to have a tendency to dart off to the left @ the end of the landing roll.

Heres a very nice link where you can download the plans for the Falco F8L (photo at the bottom) for free. No, I did not think you would care to build one as it takes forever to do, but there are some GREAT ideas & woodworking tips contained in it! Well worth the download.

Keep well all,

Henni

[Henni]

Hi everyone,

At last, some progress again. Off course you know what this means - I have found the engine I was looking for. Yes, I've found a Rotax 583 that delivers 97hp at 7250 R.P.M. When you throttle back, it yields 3.5 gallons per hour. Weighs just about the same as the Rotax 582. What more could I ask for? It will cruise like a full blooded KR2 after all. You can read more about the pros & cons of it over here.

Herewith some long promised pics of the first window sill. Note how much wider it is. Now multiply that by two. That will be the gain in my cockpit width at the shoulders. I will flare the bottom into the lower fuselage sides with thin laminated ply. Not much weight gain at all! Once again I am elated. My ideas are starting to come together and the results are even better than anticipated!

Man, if only I had a way of blowing my own Perspex canopy, I would have made myself a very nice bubble shaped canopy ala the Sting (pic 3rd from the the bottom) that will blend in all the way to the lower fuselage on the sides. But alas, I'll just have come up with another plan that will also not look to shabby at all. This project really keeps my mind going.

And lastly, the pic 2nd from the bottom is the exact shape & way I want to make my flaps. The results of these deployed are just AMAZING! Just think of what these are going to do for an already otherwise light aerie! On the MCR4S, which uses more than a third of the wing's chord for flaps, on take-off it ups the lift by 1.5 and during landings by 2.5. Just imagine that, having 2.5 times your normal lift whilst you land! Of course the KR2 uses much less of the wing's chord, but it will still make for a vast improvement. Add to that the VG's and just imagine the results. One NONE floating KR2 coming up. See bottom pic for my current aileron. Ideal for new flaps and new ailerons could be added at wing tips.

I am at peace tonight. It was a HARD choice weighing the SUPER reliable 165hp 296lbs Continental against the far less reliable 97hp 100lbs Rotax. I nearly started to turn her into yet another heavy "monster", it was just THAT tempting. By "monster" I mean being so much heavier than what she was designed to be.

I am elated now that I can continue with my goal of one of the lightest KR2s ever built apart from the prototype maybe. My goal is still achievable & I have the same horsepower to my disposal as those with the 6 cylinder Corvair engines that all weigh in at over 750lbs. empty. To have the same power available at 250lbs less would just be AMAZING, to use those very same words again. Maybe, at a later stage, I can buy one of the newer lightweight 100hp engines for her which will make her just THAT much safer. Won't require too many changes as the engine weight will remain the same. Mostly some mount & cowl modifications only.

Yes, by KR2 standards my canopy will be higher & wider, but at that weight my wings will fly at a much lower a.o.a making up for most of the extra drag that I've created. I think that I am going to be happy with her overall performance & she should cruise at the same speed most other KR2s do!

Rudi, I don't think I'll hold you back too much this time round my friend!

Anyways, keep well all my flying mates,

Henni

[Henni]

Hi all,

This is how it's done on the GlasairIII. Note that the main & secondary flaps each has different hinges, but hinging from the same pivot point.

Not sure whether this will be easier to make, but definitely worth considering. If only a single hinge point required at each end, then yes, this will be easier.

Keep well all,

Henni.

[Henni]

Hi everyone,

I am busy sanding the top of the longerons by hand where I need to attach the new window sills. This takes a lot of time doing it by hand. Another problem - My jigsaw blade is too course & I cannot cut the window sills without tearing the edges.

Thus I desperately need a belt sander and finer blades for my jigsaw. I'll be in a position to post some more pics soon. Please be patient.

All the best my friends,

Henni

[Henni]

Hi all,

Whilst my progress is a little slow, some more interesting info on the KR2:

I doubt if any aircraft have ever been designed that have been modified more than the KR2. There are a great many flying worldwide, and just about everyone is different. They are flying with Rotax two strokes, four strokes, Jabirus, VWs, Corvairs, Continentals, Franklins, Subarus and maby others. Engine weights range from 90 to 260lbs and output from 60 to 180hp.

Some have no flaps, others split flaps and even fowler flaps. Some have belly air brakes. Some have spoilers and no ailerons. Some have fuel in nose, some under cowling, some under seats, some behind seats, some in stub wings, some in main wings, some in both. Canopies range from square to round. They are opened to the front, to the side, sliding forward, sliding rearwards, have swing doors like proper aircraft to list but a few.

Elevators differ on many, have been extended, rudders differ on many. All the newest builds use a completely different laminar airfoil, not at all approved by the designer. Some are built from wood, foam & fibreglass, some only of fibreglass, some only of wood and some of wood using only fibreglass skins. The tail has been lengthened, the firewall moved forward, the fuselage rounded.

The under carriage range from anything you could imagine to anything you could imagine. Some, even here in South Africa, had water ballast in the tail that has to be drained when flying with a passenger. Some have had their main wings extended using foam covered with a little fibre glass only for main spars attached to the current boxed wooden spars. There have not as yet been a single fatality as a result.

Some have their main spars built from wood caps with wood webs and wood ply skins, others from laminated foam & fibreglass sections. Some have been modded to have dihedral right from the fuselage, others only from the stub wings. Some have their wings folded, other have a one piece wing only. The empty weight of at least one is more than 300lbs over the designed gross weight of the design, yet it flies very well on it's 180hp!

I can show pics of some KR2s that could no longer be recognized as the original design at all. Many, many a good idea came as a direct result of all of the above and many other aircraft designs came as a result of these. The KR2 has really been an excellent platform for the term "EXPERIMENTAL" to the fullest sense of the word! And the hardest thing to believe is that most of these ideas and mods came from mere amateurs without any official engineering qualification.

To my knowledge, there have only been two KR2 fatalities in South Africa. First one as a result of someone adding lead in the spinner to compensate for a rear cog that came off, took off the prop, moved the cog beyond the maximum rear position and the result speak for itself. The 2nd one, by all indications, was as a direct result of an instructor that tried to turn back to the runway under a engine out condition after take-off in direct conflict with his own teachings. Of the many flying over here, this says a lot for their safety record, modifications & all.

Keep well all my friends,

Henni

[Henni]

Hi everyone,

Been awfully quiet lately, but we've had a few developments in our lives. Firstly we had to go & fetch our boat that we've been paying off over the last few months. We finally made the last payment on it. Then I had to make space for it.

Next, before I found the Rotax 583 engine, I made arrangements to trade our tourer bike for a Aquilla 582 as I wanted the engine for the KR2. We'll it took up most of the weekend & finally now it's done & she's at her new home.

Yesterday I purchased the power tools required to continue, so hopefully as from later today I'll be able to post more progress pics on a continuous basis again. Funny how life happens - a short while ago I had no engine for my project, & now I have a Rotax 583, 582 & 532 with various gearboxes & props to choose from. I'm sure between the three I'll find the most suited one for my specific needs.

Keep well all my flying friends,

Henni

[Henni]

Hi all,

On Friday we visited the Airplane Factory where they build the South African designed two & four place Sling aircraft. What an experience is was!

They were getting ready to deliver three aircraft to Namibia, so we saw a lot of activity, including a lot of flying. What beautiful aircraft these are and how fantastic their short field & overall performance!

One can clearly see that it is a business that is well run & organized. Everything impressed me, from the design to the workshops to the actual product. These guys don't beat around the bush - they produce! Just look at the number of aircraft being readied for delivery. And the quality of workmanship on these are excellent! I could not help but observe the attention given to even the tiniest detail.

Boy, how I would like to be able to afford one of these... Well done guys! You are doing South Africa proud!

Read more here.

Henni

[Henni]

Hi everyone,

I promised some pics, so here goes. Progress was slow today. I could not decide between a orbital sander or a belt sander, so I purchased the orbital as it will come in handy when I start preparing for finishing.

I should have taken the belt sander instead. This is all I have to show for a whole afternoon's worth of sanding. Tomorrow I'll do the other side & then I can glue the window sills into place.

Keep well all my flying friends,

Henni

[Jean Crous]

Sanding with a belt sander can become a little bit ambitious, then one takes off wood instead of paint............. Patience Hennerik, patience
Groete
Jean

[Henni]

Aaaahhhh!

At last, some wise words. I was just thinking that if I go buy a belt sander, I'll cut one afternoon's work in half. Then, what would I use it for after that?

So yes, tx mate, I'll stick to the orbital for now, even though it's more than just a little paint standing in the way of gluing my window sills into place.

Anyways, nice hearing something from you. Always nice to get some feedback over here, where everything reads more like my biography than my project - I would have made a good writer...

All the best my friend,

Henni

[Henni]

Hi all,

Found this interesting write-up:

From: http://www.maddyhome.com/krsrch/thread?tt=f&on=1&hit=11

Subject: Flap Magic

Somebody opened the door by asking what the pros and cons of various flap
types are. So here is one viewpoint, hopefully not a blast of blustery
opinion.

A flap can be a multi-purpose thing. It can create some extra lift at low
deflections and extra drag at large deflections. In any case, adjusting the
angle of the trailing edge of the wing also directly changes the pitch
moment (nose down) created by the flapped part of the wing. This is a very
powerful influence, and should be carefully estimated for aircraft of the
configuration of the KRs (low wing, maybe short coupled, not very powerful
trim capability). Why? Because the extra drag below the center of mass also
creates a nose down pitch moment, and the semi-high horizontal tail reduces
favorable downwash coupling of the wing and tail.

In some extreme cases I have looked at, another complication enters the
picture. You would like to achieve higher lift flaps down than flaps up.
Ideally, then, you will get the maximum lift out of the flapped part just
before stall, while the rest of the wing is somewhat less close to achieving
it's maximum lift. This gives you the lowest stall speed. This is not
guarenteed.

Some flap/wing geometries can't get good lift out of the unflapped part of
the wing. If the flap is a powerful type (like a Fowler arrangement), the
incidence of the flapped wing can be approximated by the chord line from the
dropped trailing edge to the nose of the airfoil. So the flaps can
powerfully increase the effective incidence of the flapped part of the wing.
In a relative sense, the unflapped part is now operating at a much lower,
maybe negative incidence. In some cases this effect limits the chord of the
flap more powerfully than any other single factor. Make it too big
chordwise and your total maximum lift decreases!

Another thing. If you design the flap properly, now the tips of the wing
are loaded and may stall. Ailerons at the wing tips mean that leading edge
treatment may need to be examined to avoid nasty rolls at low altitude.

But a proper design will avoid all this, since the flap for a KR should be
there to do two things: 1. Increase drag to provide better landing control,
and 2. Lower the nose in landing to provide better visibility. If the plane
is built or loaded too heavy, the extra speed on takeoff and landing is the
smallest concern.

So my vote is with a good, light split flap arrangement. Good drag control,
incidence and pitch moment change is equivalent to half the flap deflection
of a regular flap (average of top and bottom surface at TE). Fowler is out
of the question. Plain flaps likewise not a good idea.

Walter Lounsbery
POB 54266
Hurst, TX 76054
(817) 285-8520
Walt@Lounsbery.com

[Henni]

Hi all,

At last! 1St window sill glued into place. As I do not have enough clamps, I'll glue the other side in place tomorrow. At least my cabin won't be another sardine can like the pic at the bottom, even though my fuselage width is the same!!! I think this will turn out to be a good way in which to gain much more cabin space from a stock standard width KR2 fuselage.

Well, 'fraid that's all for now.

Keep well all my flying friends,

Henni