Flettner 282 Kolibri Build

legoman

Well-known member
With the P-51 MK1a build finished and I wanted to try build a rotary wing plane. So, I posted a poll, and this seemed to get the most hype in the comments and tied for first so I decided to build it. The Flettner Fl 282 was the world's first series production helicopter.

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Bill Stuntz

Well-known member
OK, here's another of my dumb questions: Did that bulkhead behind the engine exist in the original? It blocks the airflow from the internal propeller & prevents it from blasting against that huge rudder for yaw control. Shouldn't it be open? With the contra-rotating rotors, the torque is already cancelled out. Or is it counter-rotating?
 

legoman

Well-known member
OK, here's another of my dumb questions: Did that bulkhead behind the engine exist in the original? It blocks the airflow from the internal propeller & prevents it from blasting against that huge rudder for yaw control. Shouldn't it be open? With the contra-rotating rotors, the torque is already cancelled out. Or is it counter-rotating?

*Warning copious sarcasm*

yes the firewall should be there. it would really suck if the engine caught fire and lit the wood and fabric tail on fire. I guess it should be on the other side of the bracing. all the documentation I could find said an 8 bladed fan which sounds like a pressure fan to push the small cylinder shaped through holes in the baffle behind the engine. also if it were open that would likely kill cooling as the top of the fuse is a high pressure area and the bottom is a low pressure. the rotors are also tilted six degrees forward so airflow is headed slightly reward. I believe that the low speed yaw control is done mostly by the rotors similar to the CH-47/CH-46. the rudder is there so when at speed in forward flight the engine does not have to work harder to control yaw. best yaw authority was at 60 kph and worst was at 40 kph. which suggest to me that above 60 the engine does not have excess power to get the blades to fight each other and yaw the Heli and it is relying on the rudder and near fourty is where the rudder is not very effective and the engine is working hard to fly at that speed.

how can the rotors yaw the heli? one rotor could go to coarse pitch and the other could go to fine pitch and fee some roll into both rotors to counter act the asymmetric lift. Or twist the blade so the left rotor tries to nose the heli up the right rotor tries to nose the heli down the cancel out and you left wth a yaw moment as the left blade is trying to pull the top of heli backward the right rotor trying to pull the top of heli forward.

41004 miniart Kolibri V 23t (13).jpg41004 miniart Kolibri V 23t (14).jpg2975-32.jpg
 

Bill Stuntz

Well-known member
Thanks. I had considered that, but assumed that the asymetrical lift from the rotors would yield more roll than the yaw provided by the differential drag since the RPM's need to match. And I thought the dual rotor assembly looked like it pivots forward/back and not R/L. That R/L mounting from the rotor head to the frame looks pretty rigid to me. But the fore/aft looks pretty rigid, too. I must be missing something. And my assumption was that the prop wash would need to blast on the rudder for yaw control at low airspeeds. You've obviously thought this through more thoroughly than I have and spent a LOT more time looking at photos/drawings. I've never been very good with heli's and my ineptitude certainly shows. And I find it nearly impossible to balance that unbroken egg on a plate - it feels more like I'm trying to balance it on a basketball. I more-or-less (mostly less?) understand how they work, but the mechanics don't seem to come to me as naturaly as fixed wings do. I'm REALLY looking forward to watching your progress with this build!
 

space boy

Well-known member
I find it nearly impossible to balance that unbroken egg on a plate.
it took me very many sessions, maybe 50 or so, to be able to hover my real-life RC helicopter in the 90s. Hovering is more difficult than forward flight on a helicopter.
if I had RealFlight back then, I probably could have learned quicker.

I'm saying this to encourage you to just practice. you seem like the kind of guy that can learn helicopter flying just by committing yourself to learn.
 

Bill Stuntz

Well-known member
I'm saying this to encourage you to just practice. you seem like the kind of guy that can learn helicopter flying just by committing yourself to learn.
You might be right about that. But since I can't really do it in real-life because of my vertigo, I don't have much incentive. But maybe I should re-think that. If I could REALLY control a heli, I could probably keep it low-ish & in front of me better. Looking up and side-to-side really triggers the vertigo. I've never actually fallen down, but when it really hits, I can't even stand up. I've been known to crawl to the porcelain throne to worship. And I'n NOT going to post a photo of THAT, either.
 

asj5547

Well-known member
WOW ! The Flettner FL282 looks awesome, love all the detailed frame tubing and the Radial engine that is shown. (in post 1 pics above)
Yet another exceptional model in the making from the Legoman Aviation Production Line, I am looking forward to flying the 282.
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asj5547

Well-known member
Thanks for the beta of the Flettner 282, it looks and fly's great, the only thing I would like to see is a bit more power/speed at the moment the most I can get is 55 mph in a shallow dive, the specs for the 282 says 93 mph max. (maybe that is in a steep dive)
 

Bill Stuntz

Well-known member
As bad as I am at flying helicopters, it flies pretty well for me. I found that the way the dual rotors independently destroyed themselves when I accidentally set it down in the weeds was pretty amazing. Each blade flew off independently in a different direction at slightly different times! :ROFLMAO:

But I STILL don't understand the physics/aerodynamics of the yaw control. Is it the rotor wash reflecting off the ground, blowing horizontally over the rudder in ground effect? In forward flight (or backwards, I suppose - I didn't try that) it's obvious, but in hover, I'm confused. It doesn't seem like vertical rotor wash over the horizontally deflecting rudder should be very effective, especially when attempting to hover at higher altitude out of ground effect.
 

legoman

Well-known member
As bad as I am at flying helicopters, it flies pretty well for me. I found that the way the dual rotors independently destroyed themselves when I accidentally set it down in the weeds was pretty amazing. Each blade flew off independently in a different direction at slightly different times! :ROFLMAO:

But I STILL don't understand the physics/aerodynamics of the yaw control. Is it the rotor wash reflecting off the ground, blowing horizontally over the rudder in ground effect? In forward flight (or backwards, I suppose - I didn't try that) it's obvious, but in hover, I'm confused. It doesn't seem like vertical rotor wash over the horizontally deflecting rudder should be very effective, especially when attempting to hover at higher altitude out of ground effect.

it yaws in a hover by forcing the right and left rotors to equal and opposite deflections on nose up or down. the blades "flap" up at high defection and down (up less) at low deflections or down at negative. and force the bubble of air the rotor is generating and fly on to "flow" for or aft on either side forcing the heli to yaw. these terms are probably not correct but i think they get the point across.

tilt rotor vtols handle yawing similarly but instead of rotating the pod. the heli relies on the blades and the flap linkages to flex from increased load.
 

legoman

Well-known member
Thanks for the beta of the Flettner 282, it looks and fly's great, the only thing I would like to see is a bit more power/speed at the moment the most I can get is 55 mph in a shallow dive, the specs for the 282 says 93 mph max. (maybe that is in a steep dive)
that is also the full-scale helicopter not the third scale model. I was going to make quarter scale, but the engine choice was looking like a saito FG73R5 and a painfully slow speed of mid to low twenty's.
 

space boy

Well-known member
here is a preliminary flight model of the flettner. if something is out in left field with the rotor let me know. (headspeed, stiffness, etc)
This is more interesting than I thought it would be, @legoman . It sounds really cool, first, and the rotors look SO WILD, like they're just flapping all over the place. And it WORKS! It flies nice and gently, more similarly to an airplane than most helicopters, just like it seemed to do in the video.


It's ALMOST too docile, like I wish there were more control authority. But maybe that's just the nature of this particular helicopter.

I love it and I'm keeping it and I am definitely going to get the finished version.
 

space boy

Well-known member
That reminds me of something I discovered: a modified F15 with canard fins and thrust vectoring...

1280px-F15smtd01.jpg
 
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Bill Stuntz

Well-known member
That's a really ODD photo! I did a double-take until I realized I was looking directly tip-on down the length of the extra what... canard, winglet? What exactly IS that? The visual asymetry from that angle is striking.
 
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space boy

Well-known member
I think it is a view from the tip toward the root of one of those canard thingies. 🤔🤔

(looks like I've been reduced to using technical terms, such as canard thingies! 😄)
 
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