Freebird free downloadable plans for improved KR2S

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Tom DM

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one man's trash is another man's treasure

While we all like (to find) treasures and sometimes do... yet often we don't.

"For free" quite almost gives problems afterwards, such seems the nature of the thing.

If the "for free" requires updates / follow-up , then delete "quite almost" from the previous sentence and prepare to spend far more than intended or estimated.
 

cluttonfred

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Old plans can be very educational even if you never build them especially if you are interested in design. Not only can you learn how to put together an airplane, you can learn how best (or how not) to lay out drawings and present information and inspire builders. I have a number of plans that I never intend to built but have taught me a lot. Here's one that's easy to share because it's just one sheet for the whole plane. It's not very easy to follow but it is certainly inspiring! I have a version of it framed for my office.
 

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kr2pilot

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I own a KR2S and our group is the one generating the Freebird plans. The airplane builds off of the original KR design with a longer body and offers new generation wings. This new generation KR derivative offers the choice of VW, Corvair, O-200, Jabiru, and other engines popular today in the Experimental community. The canopy of choice is the Dragonfly canopy. It is fixed gear and can be built in taildragger or conventional style gear. The airframe is wider (38" - 42") and longer than the original with a larger tail.
 
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Vigilant1

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I own a KR2S and our group is the one generating the Freebird plans. The airplane builds off of the original KR design with a longer body and offers new generation wings. This new generation KR derivative offers the choice of VW, Corvair, O-200, Jabiru, and other engines popular today in the Experimental community. The canopy of choice is the Dragonfly canopy. It is fixed gear and can be built in taildragger or conventional style gear. The airframe is wider (38" - 42") and longer than the original with a larger tail.

Thanks for the update. You guys have added a lot of helpful info to the page linked in the OP. I'm glad that the VW engine remains an option It's great that this is to be an evolution of the existing design/method of the KR, there's a lot of hard won knowledge to use.
Do you know if the Freebird will have an option for removable wings (as the KR2 does)? It's always a tough call to make (easier and lighter to build without, most folks seldom use them anyway, and yet many prospective builders want them and hangar space ain't getting more available or cheaper).
The KR community is really something. So many designs have come and gone, but this design keeps on going.
Thanks again.
 
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dwalker

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If you wander over to n56ml.com you will find that the Freebird is exceptionally similar to Marks aircraft that he built, where there is precious little other than build technique left of the original KR2. He has lengthened it, widened it, changed airfoils, etc.etc. and powered it with the Corvair motor. Most of the things He is currently flying a VW powered aircraft and there is no reason to think that a 2180cc VW would not handily power an aircraft built along the lines of what the Freebird describes.
 

Vigilant1

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Yeah I think they are going to strongly recommend the Corvair powerplant...
Hopefully the big VWs will still be an option. The given specs are preliminary. Also, their estimated empty weight is 760lbs. If that's with a Corvair, then a VW might lop about 50 lbs off, which is significant. If another 30 lbs could be found elsewhere (??), we're down to an EW of 680 lbs. Add 400lbs of people/bags and be satisfied with 16 gallons (96 lbs) of fuel and we'd have a takeoff weight of less than 1180 lbs. With 24' of wing, climb could be okay if conditions (DA, etc) are otherwise favorable and if the plane is as clean as other KRs have been.

Lighter would be better (as always), and the little engine will be worked hard. In this situation another couple feet of span would help, too, but that's a major redesign. It wouldn't be a plane for two large people and a steamer trunk. We'd expect the plane would probably feel a lot more sprightly when flown solo, I know my Sonex does. Anyway, it seems the VW might still be in the KR biz.

Edited to add: Mark Langford writes that his Corvair weighs 245 lbs. If our VW Type 1 weighs 160, then we've just lowered the EW to 675 lbs. That helps a lot (now, just need to get the CG right...).
 
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sotaro

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Alternatively, the Yamaha 500cc twin, the Phazer, is firewall forward about 135 lbs, so that would save you another 25 lbs. It might be exciting to be in one of the first Freedom Birds with a 500cc twin powering it...
 

cluttonfred

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Alternatively, the Yamaha 500cc twin, the Phazer, is firewall forward about 135 lbs, so that would save you another 25 lbs. It might be exciting to be in one of the first Freedom Birds with a 500cc twin powering it...

The day that I can order a proven firewall-forward Yamaha Phazer kit I’ll be very interested, but I am not aware of any such packages available yet. If this is the engine we’re talking about, which hits 80 hp at 11,000 (!) rpm, then I’d be very concerned about longterm reliability in the sort of steady-state operation we need in an aircraft.

 

sotaro

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On the Facebook page of the Yamaha conversions someone posted a query as to putting an Apex, the 150 hp 4 cylinder 1 liter engine, in a Tailwind. There was quite a bit of discussion of the pros and cons, with the majority writing that STOL aircraft capable of off-airport landings were safer at this point in the development of the Apex. The Phazer is in it's developmental infancy compared to the Apex.
 

KeithO

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The Viking 90 is supposedly 160lb for $10k. Pretty hard to beat unless you want a used Rotax 912 for a similar amount and still want to deal with carbs.

The 90 is a 3 cylinder engine with a balance shaft and "regular" port injectors so no direct injection injectors or super complicated engine controller. Even though its not a huge seller car wise, still very high numbers compared to any sort of dedicated aircraft engines. Mitsubishi Mirage sales approximately 22k/yr between 2014 and 2021 so in excess of 150k sold so far just in the US.
 

KeithO

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Video of slow flight in a Zenith CH 701 equipped with the Viking 90 engine. 0 indicated airspeed....
 

dwalker

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Hopefully the big VWs will still be an option. The given specs are preliminary. Also, their estimated empty weight is 760lbs. If that's with a Corvair, then a VW might lop about 50 lbs off, which is significant. If another 30 lbs could be found elsewhere (??), we're down to an EW of 680 lbs. Add 400lbs of people/bags and be satisfied with 16 gallons (96 lbs) of fuel and we'd have a takeoff weight of less than 1180 lbs. With 24' of wing, climb could be okay if conditions (DA, etc) are otherwise favorable and if the plane is as clean as other KRs have been.

Lighter would be better (as always), and the little engine will be worked hard. In this situation another couple feet of span would help, too, but that's a major redesign. It wouldn't be a plane for two large people and a steamer trunk. We'd expect the plane would probably feel a lot more sprightly when flown solo, I know my Sonex does. Anyway, it seems the VW might still be in the KR biz.

Edited to add: Mark Langford writes that his Corvair weighs 245 lbs. If our VW Type 1 weighs 160, then we've just lowered the EW to 675 lbs. That helps a lot (now, just need to get the CG right...).

So I had lunch with Mark and a couple other KR guys a weekend ago, and his comment on the Freebird is it is what the KR should have been all along. I gathered it will be very much like Marks N56ML, but also a choose your own adventure in that you can choose the original airfoil or you can choose the updated airfoil as used in Marks plane. The plans call for the Dragonfly wider and lighter canopy. From the start it is longer, wider, and slightly deeper so that unlike even the KR2S you should be able to fit two modern size adults in it. If you want it still slightly longer that can happen as well as wider, within some limits. VW power will fly the plane, but a Corvair or similar will probably fly it better, and you can put an 0-200 in it if you really want.
I feel like the wing planform will be almost identical to Marks N56ML aircraft with a couple of updates that "he wishes he had done".
It seems like The KR guys are kind of frustrated with the lack of support from the current and past owners of the plans. At some point it seems the widow basically said she did not care what happened with the plans, then somewhere along the way this other fellow claimed ownership and basically threatens to sue anyone who tries to sell KR plans or parts, even though at this time I am not sure he would win that battle no one cares to fight it. At the same time he is actively not selling anything but the "business" of making the parts and wants a bit more than a bit too much for it. It is a shame because he has the Deihl parts for the KR, the rights to the Ellison Throttle body and a bunch of other things that would be handy to have available again, he is just not doing anything with it.
Not sure that helps any if at all, and I meant to post this last week but I actually kind of forgot about this thread.
 

Vigilant1

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So I had lunch with Mark and a couple other KR guys a weekend ago, and his comment on the Freebird is it is what the KR should have been all along.
Thanks for the update and new info.
Considering that the KR2 has been very popular for over 50 years, and that Ken Rand has been gone for so long and the ownership/leadership of the company/community has been "amorphous" for so long, it's amazing that the community is holding together as well as it is. That's a testament to the work Mark and others have done.
Like virtually everyone, there are things I'd want to modify to make the plane perfect for me. It looks like Mark will use Freebird as a vehicle to further refine what he learned during construction and mods to N56ML and (significantly) to put it all into a coherent construction sequence. That'll be a pleasure to see, read, and maybe build by. He's already explaining "forks" that allow builders to choose "easy construction" vs "better looking" (fuselage sides vertical vs canted out at the top).
 
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