Whirlwing Stop-Rotor Craft


Scale model of the Whirlwing Stop-Rotor Craft.
Scale model of the Whirlwing Stop-Rotor Craft.


Heading illustration- Whirlwing Stop-Rotor Craft

#1 Whirlwing Stop-Rotor Craft

#2 (Drawing) My Other Stop-Rotor Craft Concept

#3 Whirlwing Stop-Rotor Craft




All my experiments are on You Tube and some are linked. I have made a gliding model of the Whirlwing variant stop-rotor craft (shown in the main title heading above). I also made stop-rotor test videos to demonstrate stop-rotor (along with some glide videos to test out the plane design). I also have an open rotor stop-rotor craft concept (also illustrated above). I plan more experiments, like making a bigger plane variant with a (free-spinning) stopped rotor installed on it’s back (to test it’s speed and handling). A working model would be far too costly (at this stage) cos nobody makes the required software (for the two side rotors). One day I may get sponsored, or a working model of the X3 may come out. And I could probably make my model from that (cos it would have the software). But the helicopter part is already proven with the full-size Eurocopter X3. But transition hasn’t, and plane mode with stopped rotor hasn’t been proven.


Aircraft mentioned in this post are pictured above.

My idea is inspired by the Europcopter X3, which is basically a helicopter pushed through the air by propellers. So, in effect, my stop-rotor craft idea is an extension of the X3 concept. One step further, to make it a completely different craft. With the X3 the two side mounted propellers are also used as a tail-rotor (in hover). But with the X3, the main rotor spins at all times, and when at maximum speed there is a lot of drag, and it requires at least double the power (per seat) than a plane to do the same speed. It’s obvious that the spinning-rotor-drag is the problem. But with a stopped main rotor, the blades would be no worse drag than (say) an undercarriage (see illustration of my open rotor variant stop-rotor craft above). But when the main rotor remains spinning in forced forward flight (as in the case of the X3) the blades on one side do nearly 700 mph (400 mph faster than the X3) and the receding blade is effectively going backward through the air a hundred miles an hour. So there is immense drag on one side, holding the craft back, and it would probably nearly require double the power than with a stopped rotor (to go the same speed). Whereas a plane will need less than half the power to go faster than the X3 (as with the Avanti plane). So the stop-rotor still won’t be as efficient as a plane but is closing that gap considerably (I reckon). With the stop-rotor craft, each blade at the rear of the 3-blade stopped rotor, is (obviously) going the same speed as the craft. So the drag is less, and the drag is even on each side (instead of being much more severe on one side). So the Stop-Rotor Craft still won’t be as efficient as a plane, but (at-the-very-least) if should meet half way between a plane and the X3… A vast difference, but I reckon (and hope) the stop-rotor would be a bit more towards plane efficiency than exactly half way between a plane and the X3. And there is a window…a plane that goes a hundred mph faster than the average efficiency plane (with similar number of seats). A finely refined fast plane. So why not use that company (Piaggio) to make the Stop-Rotor craft (plane part)? The stopped rotor is allowed to hold it back a hundred mph and it still would retain (average) plane efficiency (if we base it on the Avanti). lol But not quite. It will be heavier and need a bit more power to go 300 mph. Say half again, instead of over double (as with the X3) so the stop-rotor craft won’t be quite as good as plane figures, but it still looks good on paper. And a stopped rotor may only hold it back by (say) 60 mph. If that’s the case, it looks good and we could get close to average plane efficiency if we have a particularly efficient plane and stopped rotor design (all fared). This thesis has all the figures that indicate this as a real possibility.


First see these short videos: (Copy&paste link into search bar if link won’t work.)

Stop-Rotor Test… https://youtu.be/VgMpsr0UchY (short)

Whirlwing Glide Test… https://youtu.be/LdGdiZHqpK8 (short)

Whirlwing 5-Blade Stop-Rotor Test… https://youtu.be/VyjBDA0NjPI (short)

Whirlwing Auto Rotate Glide Test… https://youtu.be/5XxW65KgkUM (short)

Whirlwing Stripped Down Glide test… https://youtu.be/9g8o7gH6GMo (short)

Also see this: (at your leasure)

Stop-Rotor Explained… https://youtu.be/LhE2VGAkLWM (long video)


Welcome to my stop-rotor concept. This is the Whirlwing stop-rotor craft. Unlike most stop-rotor concepts, this one isn’t used for lift. When the rotor is stopped in the air-flow, one of the blade aerofoils is going “backwards” into the airflow. So it won’t work as a wing (as has been tried before, with minimal success). This stop-rotor is used for streamlining only. No lift is produced with my stop-rotor design. It only reduces drag.

When it’s a plane the rotor stops in the position shown in the illustration (see main heading photo). There are links just above this rant for videos of my stop-rotor tests. I call the forward pointing blade the “lance” blade, and the two rearward blades the “jet-wing” blades (for obvious reasons) (and any blade can be the “lance” blade, depending on what position the rotor stops). And the two side rotors act as aeroplane propellers and push it through the air. It’s just a plane, with a stopped rotor on its back.

When it’s a helicopter, the main rotor is powered and the two side rotors act like a tail rotor, by thrusting opposite… and this is done by changing the pitch of the side rotor blades. This is to counter the torque on the main rotor (like a tail rotor does). So it’s just a helicopter (with stub-wings). The two side rotor idea is a great idea, but it’s not my idea.

But this particular type of stop-rotor is my idea (none other I know of).  And I’m applying my stop-rotor idea to the side rotor concept (that’s from another aircraft) to make it a pure plane (with a stopped rotor on its back)… instead of just a helicopter pushed through the air.

So, to stop the rotor, we simply give the craft a low angle-of-attack and give the blades neutral pitch. And thrust both side rotors backwards, so it thrusts the craft forward.  With neutral pitch, the blades will stop (even with some angle of attack). Or (as you saw) the rotor will stop with pitch on the blades, if there is no angle of attack. If we give the blades reverse-pitch, the rotor will spin-up in the right direction (that is, if we give the craft about 10 degrees angle of attack). Good for a quick rotor start-up.  Then we apply the clutch and apply power to the rotor and give the blades normal helicopter pitch. And also make the side rotors both thrust opposite to counter the main rotor torque (to act like a tail rotor).

With the stop-rotor craft, there is no “transformer” shape change. The craft stays in one piece. It does it all (from chopper-to-plane and back again) just by mucking around with the pitch of the blades of all 3 rotors, operating the clutch on the main rotor, and changing angle of attack, to about 10 degrees. And (of course) software would be essential for this (especially for the two side rotors). But that’s already been done, so that part is proven.

Most of my stop-rotor craft has been done before… Well, not all of it, but most of it. It’s all been done except the stop-rotor part. And that’s why I did this project. To give an already evolved helicopter that extra evolutionary push, to make it a completely new species. lol And stop-rotor is really only a small step in technology, as you will see. But with such a small mod, the whole thing is a completely different thing (it evolved) and is now up with the BA 609. And could even challenge the BA 609 in economy (if not in speed).  There is solid evidence that the stop-rotor craft would be much lighter than the BA 609. The Eurocopter X3 is just about identical to the stop-rotor craft, that is, you don’t need any extra major stuff, just a replacement part. So the new part shouldn’t weigh much more than the original part. And that part is the main rotor. Replace the whangee 5 blade rotor with a 3 blade ridged blade rotor…a different part, not an added part. But here is an added minor part…a clutch on the main rotor. I don’t think the new weight would be 2,000 kg heavier. lol That’s how heavier the BA 609 is compared to the Erocopter X3 with (potentially) the same amount of seats and same hp. I say (potentially) cos the X3 is an experiment and the empty weight could be high, but (according to Sikorsky) a similar craft is in-the-making. It’s meant to carry up to 8, with just over half the hp of the X3. (The Sikorski S-97 Raider) It is based on the Sikorski X2 (which has flown). The BA 609 is 2,000 kg heavier than the EurocopterX3, which is heavier than the Raider plans to be. The BA 609 only carries about 10 maximum. My guess is that much of the extra weight would be the tilt stress stuff and extra fuel (for a reasonable range). Weight data is all based on gross weights (maximum take-off weight). The stop-rotor craft is not just a helicopter, like the BA 609 also isn’t. But the EurocopterX3 is sort-of basically still a helicopter (just a push along one). And it is a start to a new completely different class (if they only stop the rotor). Or (more accurately) make one with a stop-rotor. And the X3 is what inspired me to apply my stop-rotor idea to it (cos of like its “plane propeller” setup and stub wings). The X3 is an emerging new type of plane, and you can see that in the illustration. I’m just taking it a step further, to bring it to a new level. lol And I have an equally radical (super simple) and effective addition to the Sikorsky Raider. lol

Just by stopping the rotor, the X3 could become the class of the BA 609, without the transformer shape change (and hopefully without the whole 2,000 kg extra weight). The stop-rotor craft also stays in one solid piece. Also it should be lighter, simpler and cheaper and easier to make, than the BA 609, and (pretty-much) do the same job with less hp.

This is the Eurocopter X3. It’s a helicopter that is forced through the air by plane propellers. And the propellers are where I got the propeller idea from. It’s much the same as my design, except that with the X3, the main rotor keeps spinning at all times. To show you how much drag this makes, all I have to do is compare planes that go a similar speed, and have a similar amount of seats to the X3. And by the figures I have from Wikipedia, the drag requires at least double the power to get the same speed. I will show you the comparisons later in this video. Also read it in the description below, and you have to think how on earth a spinning rotor can hold it back that much.

With the X3, the drag is only on one side, cos the advancing blade is going faster than the receding blade (compared to the airflow at speed). At full speed, the rotor spins nearly at full RPM (only 15% slower) and the advancing blade is going much faster than the craft. In fact, it’s nearly the speed-of-sound, at full forward speed of 293 mph.  The X3 is going nearly 300 mph and the advancing blade tip is going nearly 700 mph. lol And there is always a yawing cos there is more drag on one side (and correcting could even cause a bit more drag). It can be probably corrected by rudder or/and by the side propeller on the advancing blade side (given more pitch on the blades).

When the rotor is stopped, there is no braking system (there would probably be no need). And if a braking system was required, it’s a safety issue, cos what if the brake sticks and can’t be released (for some reason)?  The rotor just remains “free-spinning” when it’s stopped and the airflow keeps it in position (like in my stop-rotor tests).

With a stopped rotor, there would be less drag, and the drag is on both sides, cos when it’s stopped, it’s still free-spinning . So (being free-spinning) the rotor sets up its own center-of-drag, and thereby makes the drag perfectly even. And with fly-by-wire technology, we can make the rotor blades at any pitch, individually. Why? When the free-spinning rotor is stopped (in the air-steam) the rotor sets its own center-of-drag, and the forward pointing blade (the “lance” blade) should be perfectly pointing forward. That is, if the pitch of the two rear blades (“jet-wing” blades) on the main rotor, are set for the drag to be as even as possible (even with one “jet-wing” blade air-foil going backwards into the airstream). The backwards facing “jet-wing” blade air-foil would have a bit more drag than the other “jet-wing” blade air-foil (at neutral pitch) that is when the rotor is stopped in the air-stream. And so, the” lance” blade of the main rotor would not be precisely pointing forward. But…Just a slight twitching of the two “jet-wing” blades would make the lance blade straight. Whether it would decrease the drag is debatable until it’s tried. lol It would look better, but. lol And that’s important! And more trustworthy to fly with the rotor exactly straight (even if it’s just a psychological thing) and that’s important too


Whirlwing Stop-Rotor Craft




Whilwing Stop-Rotor Craft
Whilwing Stop-Rotor Craft


The Whirlwing is the name of one of my stop-rotor craft designs. There are several other variants of stop-rotor crafts that I have thought up, but this post is for the Whirlwing, a closed rotor variant. Good for confined spaces. And instead of blowing air all over the wing (with the main rotor) the wings are outside the roror disk, level with the rotor disc, making it a closed rotor. The two side rotors are also ducted fans. (coming soon)