Cloud Dancer

[rotor]

Here's a nifty little gyro from Rotortech Germany - the Cloud Dancer

More pictures here in the Gallery (http://www.rotorcraft.com.au/photoplog/index.php?c=54)

Here's a link to their site: RotorTec (http://www.rotortec.com/)


http://www.rotorcraft.com.au/photoplog/file.php?n=473

[Mitch]

G'Day Rotor,

Had a good look at the video and all the gallery pics.....nice ship.

Again I am suspect of the use of stainless in gyroplanes, that'll set the 'cat amongst the pigeons'.

And whilst it is sleek and pretty and almost has that new car look to interior, I dont like this setup....no redundancy.

Cheers,

Mitch.

[Mitch]

OK,

How about this bracket arrangement?

Thoughts.....

Mitch

[splashdown]

That engine bracket does look a bit agricultrural but I'd be more concerned with this....

2653

Control arms that appear to be crimped together? and no locknuts??

[niquenaque]

Yep, dodgy bits everywhere!! [flippant remark] Your analysis of the bracket is a good one, I would tend to think they have a bolt going through horizontally as a vertical bolt would have to be spaced off to avoid the issue you raised with radius on the corners - speaking of which you may note the non - radiused cut of the vertical fin plate in this bracket - a bit rough if you ask me, though I think it would be strong enough initially there may be a bit of flexing on the bracket which would lead to the vertical fins cracking - not good.

The other thing too is that the bracket can rotate if only fixed on a single bolt. I suspect it is designed like this because it is a connection which nominally lives in tension, though this is a guess without a damn good look at the machine in person. For my money every connection should have at least three bolts to diffuse the load and avoid stress raisers caused by the bearing load on the RHS that is suffered with just one bolt in the connection.

As to the fuel pump redundancy - pah! who needs it in a gyro?? Yes, joshing again, fuel redundancy is very, very nice to have when you´ve got a fuel pump failure just on take off when your glide path is going to take you into a fence... Phil Wrights two seat trainer makes use of two pumps on take off and on approach, the second unit is turned off when S&L flight is established.

I concur with your objections to the stainless, having been the near victim of two such failures on my gyro:chainsaw: - once with the rudder which was discovered thanks to some rotor flap, and then the first nose wheel bolt which was discovered due to taxiing through some rough grass [not the Manilla folder incident - that came later]. There are some aircraft which use stainless steel sheet as the aileron hinge - madness:crazyas: if you ask me - especially if the stuff can´t hold out as a static bracket.

As to the control rod, it could be swaged and glued. With my experience with such pipe work connections you´d be hard pressed to pull it out with the loads that are imposed on the system, but, as we know, time will tell how good it is, I just wouldn´t want to be there at the time it chose to fail if it was prone to do so. Putting a bolt through it may make it just as weak when you come to think of it. The lock nut may have been omitted if they made use of locktite or have a nylon locking strip included in the thread of the rod eye, though with a few adjustments this could be an issue as well.. consider the invisible grub screw...

Cheers,

Nick.

[Mitch]

G'Day Nick and All,

Nick I was referring to the control lever arm welded bolt.
See attached

Splashdown have a look at the bottom of the push rods.
Most of the tubes are finished in this manner......

It looks to my untrained eye that the tubes on this craft can all be adjusted plus or minus a 'bees dick' and that the front keel mounted bracket discussed above is 'held' in tension. This allows for easy build with plenty of scope for 'forcing' components not fitting just right, to come together.

For my mind you can put the whole thing together loosely and then adjust all the tubes until it locks the bracket in place. If this is the case then accuracy of alignment etc could be compromised?

I do not see how a bolt could be passed through horizontally, in this instance as the tubes in the bracket appear not to allow enough room and remember this is an articulated joint, Moving with the movement of suspension.

I do not like these stainless fittings on Alum or on gyros generally.

How does one get a stainless mast that has a crack in it repaired?
Replace it OR Re-weld it?

Cheers,

Mitch.

[Mitch]

Further,

Maybe it's the photo or my eyes but it looks like there might be a subtle 'kick' bend in the mains tubes where they couple with the shock strut plates and axle tubes etc.

Anyway,

I love the pod and the interior, would look great on my gyro.

Mitch.

[Mitch]

Looks to me like the struts could be stainless...

Mitch.

[niquenaque]

Ah, yes, such an arrangement could have you playing a harp above the clouds, rather than dancing..

The bolt may also be arranged such that the threaded section is in the shear plane - which is basically how my first taxiing incident occurred - the nose wheel collapsed and fortunately I had no rotors on, so it just fell down at the nose and stopped.

The bolt, though larger than normal is only in single shear, it should as you have pointed out be in double shear..

Cheers,

Nick.

[Mitch]

G'Day Nick/Rotor,

I emailed John a few days back and had a reply. Said he was happy to answer questions re: Cloud Dancer.

Emailed again last night with a few questions including cost, will advise.

Mitch.

PS. Everything working Geoff, Firefox and Explorer, cleaned out in the 'tools' like you advised.:cheers:

[rotor]

G'Day Nick/Rotor,

I emailed John a few days back and had a reply. Said he was happy to answer questions re: Cloud Dancer.

Emailed again last night with a few questions including cost, will advise.

Mitch.

PS. Everything working Geoff, Firefox and Explorer, cleaned out in the 'tools' like you advised.:cheers:

Good stuff mate ... computers are a bit like polies - leave em to their own devices are they can become corrupted - a quick clean out and they start to perform again ....

[Bell430]

Hi guys,

What do you mean by 'double shear'?

Are you refering to having the bolt long enough that the threaded portion extends past the mating surface, ie only the shank is in shear on both ends of the bolt ....... or something else?

Thanks

Paul

[Mitch]

G'Day Paul,

For my mind it's having both ends of the bolt doing the same job/sharing the shear forces, that the bolt in this arrangement is doing and is more vulnerable to sheer off. Yes/No?????

Nick, Tim Mc Sam and many other will know the correct answer.

I just did not like the set-up when I saw it.

Cheers,

Mitch.

[Mitch]

G'Day Gents,

Got a couple of indepth emails from John on this gyro.

I have asked him If I can release testing data etc here on the forum.

I have asked questions we have raised here and his answers are extensive.

Full info tomorrow. 34000 euro = $57300 AUD presently, plus import freight etc. Full Cert to British Std/acceptance. Rigorous process.

The red paint job on the web site was extra.

Mitch.

[Mitch]

G'Day Gents,

John has been very forthright in answering questions and frankly I'm impressed with the level of analysis and testing that has gone into this gyroplane in order that it pass the British Certification.

Getting back to your question’s on the Mast and Keel. Mast is made out of 2 Sections 50 mm by 25 mm with a wall thickness of 3mm making it to a Mast of about 2” x 2“ in Alum 6061 T6 Keel is 50 mm x 50 mm with 3 mm wall thickness. Some of the Cluster Plates are made in Aluminium 7075 T6 Cluster Plates at high stress Areas like at the Rotor head and the Connection to the tail section we use Stainless. The Fasteners in this Sections are AN Grade installed the correct matter as known to Aircraft spec. The frame Drop Tested under very high load to meet the BICAR Section T in every aspect.

The Tubes are made partly out of Aluminium and partly out of Stainless. The axel tube made out of stainless has in the stress arias steel inserts to be able to carry the
Heavy lodes not only applied in a drop test. The push rods are stainless crimped at the end und suitable of loads in excess of 3000 kg They are adjustable and made out of 2 sections on each side with an adequate hinge arrangement approx. at the middle of the mast.

The bracket on top of the keel is made of stainless taking the load vertical from the Motor and horizontally and for the axel tube vertically. The bracket it self is not sitting
with the radius on the tube but is held in place with an adequate AN Bolt horizontally thru the Keel.

We use Stainless parts (welded or not) only in areas of low or no vibration. 75 % 0f the frame is made of high grade aluminium but for some parts we are better of using it. The Axel tube has been made of Aluminium first, but the drop test ( 3 G) killed it totally and showed it is not suitable in this area.

Greg you will find on the web site more information what is included in the cost of the
Aircraft www.rotortec.com/cms/index.php?page=871 (http://www.rotortec.com/cms/index.php?page=871) and the price for it. The red one is sold already but can be made again next year. There are no more delivery’s planed 2007, orders taken now will not be served before Feb. of 2008 Presently we are looking for partners willing to help us with distributing the product at the future.

We are very open and like to answer any question. We also like to now if anyone can see any problem, with the design, or any other aspect since we believe that 4 eyes see more than 2.

Enclosed I have 2 Pages for you, one is showing the trust line of the aircraft related to the centre of mass and on the other 2 pages are the Test results and loads applied to the Frame.



.................................................. .................................................. ....................


Hi Mitch,
will always call you Mitch no problem ! If you like to sheer Information feel free to do so, we are building aircraft for our customers not for our ego.

I can see your point on the push rod attached to the Bolt on the control arm. First of all it would be very easy to bring the bracket around insert the bolt und tighten it up. Be believe it is not needed, the simulation for stress on the CAD shows now stress in this area. As on the sheet I have send you yesterday you will find under point 3.3 and 3.6 that the max load in this area will never more than 68.04 kg of pressure. The set up as is now will support more than 10 times of this. The nut is pressing against the eyebolt in the Rod End holding it tide to the control arm. This lives the weak
point in the Rod End itself. But to do a change and make it a double bracket is no problem at all.

On the bracket going to the keel supporting the engine mount we have some sheer moment. The AN4
Bolt in this area is taking the load and never gave us any problem. The engine has 45 kg and we tested this section to 4 G as you can see under 7.1 and 7.2 in the document send yesterday.

About the cluster plates in some areas where we us Stainless I like to ad that we have to us them for more strength. Like the Cluster plates where the Keel mounts up with the Tail section. In this area there is a very high stress point in all directions. Even more on a fully enclosed aircraft. The Horizontal and Vertical stabilizer has to carry far more load then on a open machine. Therefore we decided to us Steel Instead of 7075 T6 All our Steel Parts are cut with Water Jet and we have no surface hardening in the Plates ore around the cutting edges. Don’t get me wrong, but when I see the tail section on your Butterfly where it is attached to the keel tube it gives me some heartbeat to. But when it works, fine. We would not get it approved here. An the picture I send you yesterday we had to proof a side lode of up to 225 kg for the tail section and his attachment to the keel is needed.

Enclosed I have a picture showing the Engine support. There will not be very much Vibration transferred in to the frame of the Aircraft. Most will be absorbed by the 6 shock mounts in the engine Support itself.

For any more question feel free to contact me again.

P.S. About the cabin you like I like to tell you that the weight for the full Cabin including the fuel cell is only 12 Kg in total.


Best regards

John

.................................................. .................................................. .........................

I think this bloke has a fine gyro and I'm impressed with his openness.

Thanks John.

I did ask more questions of John and will post that and another pic tomorrow.

Cheers,

Mitch.

[Mitch]

G'Gay Gents, I have cut and pasted two emails into one here for the purpose of continuity. This is what John has to say about www.rotortec.com (http://www.rotortec.com) 's new pre-rotator.... ROTORTEC PRE-ROTATOR We at Rotortec have made a new Prerotator very unique, reliable and no wearing parts. Nothing on it can go wrong ore brake down. We have applied for a World Patent on it and I can personally tell you, it is a killer Unit. You do not need drives wheel's clutches, belts, Pulleys, Chain's Gearboxes and all the silly things people put on there Gyro's . All you need is our Rotortec Prerotator, Install it, push a button and our new Prerotator, speed,s the rotor up to 300 rpm and up you go. How about this. You can change it out for any Wheel Gear Unit like (Wunderlich) and it is very simple and very easy to do so. It is lighter in weight than the Wunderlich Prerotator with all his Parts. The Prerotator will be available for everyone and is suitable for any design Rotor head. As mentioned before I will post the Video on our web site possible in the next coming week. And as I said before, it is a Killer Unit and it will change the way of Prerotating Gyros forever. From John ex Rotortec John seems like a good bloke, genuinely interested in advancing the sport, his Cloud Dancer and getting more time to fly. Good on him and I wish him every success with his gyroplane and plug and play components. Cheers, Mitch.

[Gyrodes]

Ah Mitch, No good for you and me mate, the electromagnetic drive will intefeer with your bionic neck and my bionic ears :D:D:D. Thanks for the informative post. I forgot and PB's bionic teeth :cheers: ,
Des Garvin

[Dewie]

That engine bracket does look a bit agricultrural but I'd be more concerned with this....

2653

Control arms that appear to be crimped together? and no locknuts??
Heavy vehicles use crimping on draglinks and control arms where no adjustment is required, so it would not be a problem.

[Mitch]

That's right Dewie!

In this case it appears John has crimped fixed fittings at one end and adjustable rod end at the other. Personally I like it, it seems to me there is some adjustment available on each of these tube setups throughout the craft.

Anyone want to guess on the thrustline offset.

I have a drawing/schematic which John forwarded, which I will put up here tomorrow, very interesting results.:D

Cheers,

Mitch

[rotor]

Thanks Mitch ... looking forward to seeing that


rotor

[Mitch]

Come On Fella's,

Thrustline offset....?????

Come on PB, you can pick em, said so on the American Forum.:confused: Hmmm!

Mitch.

[bones]

Ok Mitch, i'll bite, after looking at the picy on the front of this thread, and bearing in mind that it is pasted by the poms, i'll say about 1" high or low or some where in the middle :D:mrhappy

No i go with under 1" high :confused: i think

[Mitch]

Hey Bones,

I'd thought PB would have a 'stab'.

I'll see if anyone else wants to have a guess.

Come On where are all the Xperts...:blahblah::censored::D

Mitch.

[Mitch]

You're the winner Bones!
Shame you were the only contestant. But your eyeballing skills are top notch.
PB would be proud of you;)

[Graeme]

And the first place prize is??

[splashdown]

Ahh Mitch, I think you have a problem.

That hang test pic says an 85KG pilot. How many of you fat buggers would make that weight these days? :poke::poke:

[SamL]

You're the winner Bones!
Shame you were the only contestant. But your eyeballing skills are top notch.
PB would be proud of you;)

A heavier pilot would lower the CofG and increase the offset.
Another thing is aerodynamics, a machines vertical centre of pressure, placed above its CoG will cause it to fly like it has a HTL.
All very interesting :confused:

But this little machine looks like it shouldnt have such a problem.

Sam.............

[Mitch]

Splashdown,

A days 'fasting' and a good crap should see me make the weight.:rolleyes::D

Sam,

You used the confused icon....what are you thinking?:)

Mitch.

[bones]

You're the winner Bones!
Shame you were the only contestant. But your eyeballing skills are top notch.
PB would be proud of you;)

See Pb been yteaching me well, hehehe ummm yeah
Mitch i must be getting old be frigged if i can see the measurements on that drawing, what is the finial result, since i was the only contestant, and winning is no big deal, bit disappionted no one else had a slash at it, but pB's puter was more than likely playing up and not working....

[marko66]

Hi Splashdown

Being one of those fat buggars mate i'd probably nudge that figure by twenty five kilos or maybe more suited up and in flying mode so I guess that will give a few guys a point to aim at.:cool::cool:


Regards Mark

[SamL]

Splashdown,

A days 'fasting' and a good crap should see me make the weight.:rolleyes::D

Sam,

You used the confused icon....what are you thinking?:)

Mitch.

I was only playing Mitch :mrhappy
Check out the pic bellow, and notice the blue thrust line. It is angled down compared to the machines level flight attitude. The level flight attitude is confirmed by the HS.

Regards SamL

[Gyrodes]

Looks about 90mm or 3.5 inchs HTL to me looking at Sams lines. Des

[Mitch]

Bones,

This is the description I pulled off John's website for the pre-rotator Prerotator: Over electromagnetic clutch and automatic belt tensioner. Cardan drive and shaft to the rotor head.

The Schublinie is the thrustline which runs through the vertical C of G. denoted Schwepunkt. which translates into english as 'emphasis'. I ran a few lines through (dependant upon my assumption that the HS is in Line with the Keel) and found the stepped keel gives the HS a slight negative angle of incidence.

I am posting this Sam and have not seen your diagram yet BUT I reckon this is a CLT with a HS that presents a neg incidence and with the fuel burning off from around the pilot, IMHO this gyro would be in the stable group. I also think the empenage reaching around and covering the engine coupled with that tail on a long enough moment will make the aircraft stable in yaw even with the canopy on.

Now to see what you put there Sam.

:)Mitch

[Mitch]

Exactly Sam. :D

I took it a step further, assuming HS is in line with keel, which if you run a line you will find it has slight neg angle and approaches from left to right the line drawn as ground reference line touching bottom of both front and rear tires.

The angled thrust line through the vertical C of G with a tad neg incidence HS and a centre of drag which looks almost coaxial with the thrustline, IMHO I believe this ship would be very nice indeed.

Hey Des,

Mate I believe the angled thrust is a design measure which lowers what would otherwise be a 3.5" HTL. Bensen I believe used to have a 2 or 3 degree down thrust in his designs.

Mitch.:cheers:

[Gyrodes]

Your observations there Mitch will depend on the accuracy of the pic.
To all, my observation is that the COM in flight conditions will be to the tail more. Look at any gyro in S&L flight and the rotors are nose up at somewhere around 8 to 10 degrees.
Big ? what is the engine out paramiters? Oh I forgot that just never happens with modern engines:mrhappy. :cheers: Des

[Mitch]

G'Day Des,

How are you Mate?

My copy is a full size PDF file and is from the manufacturer.
The centre of mass is depicted as per the hang test with full fuel and 85 kg pilot.

I believe John's hang test to be accurate as everything is done to satisfy the British Certification process and then the German process's all of which are far more stringent than US or OZ.

If you like I can email you a full size copy.

Hope youy are well and getting airbourne at every opportunity.

Best regards,

Mitch.:)

[SamL]

Your observations there Mitch will depend on the accuracy of the pic.
To all, my observation is that the COM in flight conditions will be to the tail more. Look at any gyro in S&L flight and the rotors are nose up at somewhere around 8 to 10 degrees.
Big ? what is the engine out paramiters? Oh I forgot that just never happens with modern engines:mrhappy. :cheers: Des

G'Day Des
I think I know were your comming from.
Yes the rotors do fly at about 8-10 degrees (trimmed) in straight and level flight.
The picture shows the machines hang test results, and I have merly added ground, thrust line, Vertical and horizontal references.
During a hang test the blades are not required to be fitted and so in the above picture, the manufacturer has merly included them in and shown them at there full stick forward (level) position.
The CofG seems OK and the only comment I can make is, I would have preferd it to have been measured at half tank of fuel.
Some people will do it as Cloud Dancer have to show that at max all up weight you will still not run out of back stick during a flare.

Regards Sam. :)

[Gyrodes]

One of the things i wondered with the hang tests is why not do the empty with the 30 minutes reserve reading, Then the half fuel test and the full fuel test. That would give all the weight senerio's.
Des:rolleyes::confused:

[SamL]

One of the things i wondered with the hang tests is why not do the empty with the 30 minutes reserve reading, Then the half fuel test and the full fuel test. That would give all the weight senerio's.
Des:rolleyes::confused:

Doing it the way you have suggested Des, would give you a better indication of the keel angle and remaining stick movement at all fuel load amounts.

Sam.......