Vertical Descents

[asra]

Cheers Des, yes lurked on this and other Aussie sites for a while, lots of good stuff. Often see some of you Downnunders over on the Rotary Forum giving us the benefit of their experience.

[asra]

For my .1 cents worth.Luckily when my instructor heard of my plans to get a Rosco he warned of the design"s tendency to spin in a vert decent. Found that to be true. Propwash over opposite rudder with forward stick has worked.

[asra]

GTG KRUZA executing a few rotations.Regards SamL......http://www.youtube.com/watch?v=2c3rqBkxiO4

[birdy]

Would be very interesting if anyone knows why the machine does this?Yes Baden, our rudders aint worth jacs ina VD without abit of power on.And the rotation in your type machine is generaly the "advancing/retreating" airflow over the prop ina VD.The left hand 912 prop has greater AS on the left side, coz its go"n down and the air is comen up, so you get more thrust on the left side of the prop disc, rotatng the machine rite.

[Brian]

One of the most important instruments a gyro can have [and I have now seen the same on an R22 & twin turbine Squirrel,] is a yaw string, mine is on the UHF aerial on the nose and if you keep a eye on that string or cotton, it well tell you at all time what the gyro is doing in relation to all aspects of flight.Over the years I have done most things yo can do in a gyro and at all times, I reference what I"m wanting the gyro to do in relation to that bit of string as it doesnt lie. eg, if you are doing a flat

[birdy]

Birdy, when you get time do another bit on rotor management as it seems to me some pilots are forgetting the rotors??????????????Wot do you mean "do a bit"?I been do"n plenty of ungyro things on these spastic tip weighted Gerrys. I usualy take wotever Chuck Beaty says as gospel, coz he knows his s**t, till he said Gerrys blade profile "goes to hell ina hand basket". ???Unless, of course, i fly like hell ina hand basket.

[Brian]

Yeah, I noticed that Chuck didnt think too highly of the Gerrys profile but if they work for you, then thats great !! Wouldnt worry too much as if they were as bad as Chuck reckoned they should be, then they would be nearly useless.

[IanM]

I would like to commend Birdy for starting this thread (5 years ago) and his thoughtful and knowledgeable information on both vertical descents and spins.

[birdy]

The only real way of known if your ina controled flat spin or ina reversed airflow spiral is the machines attituide.Ina flat spin, intentional [ controled] or not [ you dont know why its spin"n] the keel will be close to level.In spiral, the machine can become "locked" into a nose high attitude.Unintended rotation ina flat spin is generaly caused by the unequal AOA on the prop blades from the virtical airflow, causen the dropn side of the prop to produce more thrust than the riseing side.Extra power will give better rudder effect so you can just rudder out of it.

[asra]

Seems a while since anybody posted here, so I guess the thread pretty my covered what had to be said.Managed to get a little bit more time in different machines since I last posted here and I like to see how they handle in the various maneuvers including vertical descents. What has been immediately noticeable is the rate and degree of reaction time to control inputs between the various singles when flying them. So far I have tried two different Bensens two Crickets a Merlin a Hornet and an AV-18. These had various rotors, Dragon Wings, Rotor Hawkes, McCutcheons, Layzels and Rotordynes.Reassuringly they all seemed to handle similarly in the vert descents, all seemed to enter and recover from turns while doing so though some were noticeably more sluggish. The AV-18 (an unpodded Campbel Cricket) while the Bensen B-18 which was flow with the Rotor Hawkes and Rotordyanes seemed the most responsive. Approximate rates of vert descent around 1800"-2000" fpmHaving done one tail-slide intentionally quite early on I have tried to avoid doing so again, and so far seem to be able to keep all machines tried, under reasonable control and with no airspeed registered. Recoveries had varying losses of altitude from initiation the Merlin having the biggest, however it was also the heaviest machine. In most cases the rotors were 22" in two cases with a Bensen and the Hornet 23" and recovery was between 200" and around 400".I was not taking notes and so please understand that these figures were approximate and all subject to memory.

[eigyro]

I took the time to re-read this thread from the beginning last night. Great thread.One observation, if I may.I enjoy vertical descents, but I approach them cautiously, as my skill level is not nearly up to dealing with backslides.I slow down gradually to zero AS. True zero, as per a well-positioned yaw string. As I dont trust my engine at idle for too long, I keep a little throttle on, not far above idle,and adjust the stick fore-and-aft, to achieve zero AS.So I"m balancing a little forward thrust from the engine against a little rearward rotor thrust.Apart from anything else, this gives me good rudder authority, and reduces the likelihood of reversed airflow over the rudder.This seems to work fine, generally,One occasion, however, I let the yaw string move a little forward, indicating rearward movement of the machine.Then I noticed the stick wanted to move forward of its own accord.I let it do so, and the nose dropped gently and I flew out of the VD without much height loss.I thought about it for a while, and I reckon the uncommanded forward stick was actually the rotor tellingme it was seeing airflow coming in from behind, and "blowing forward".Not sure I would want to rely on it, but it was the forward stick movement that alerted me.I note that on Roy Davis"s demo flights he does a lot of VDs and serious backslides, but he seems to keep a lot of power and backstick on, and the smoke trail seems to indicate airflow over the rudder is not reversed.Nice balancing act.Roy in action;http://www.youtube.com/watch?v=Gsdkt...7WlwVTFYvKusBA

[RossM]

Cool bit of flying!, on the link.

[Disco]

That"s awesome isn"t it.

[MadMuz]

What a great thread, it definately is good it is still popping up as it is still as relevant as ever. As Ian touched on, IMO, the key to a safe vertical descent is the gyro must be hung correctly. I watched a mate in Canberra vertical descend from about 300" onto the ground.... he was ok but the machine detonated in the usual way as it touched down. I am guessing it must have been about the same or similar impact and gyro

[birdy]

So, the machine was spiraling to the left... why? There is a tiny bit of bearing drag in the rotor head bearing, so with the tail (picture a V tail in your head) hanging well below the prop wash and having no airflow to do any good.... no horizontal stabliser effect when airflow coming up from under a V tail in descent, there was no chance of recovery.No chance of recovery??? Really??If your rotor is still attached and spinin, and your stick is still attached to it, there"s NO reason to think theres no option.You could have a rudderless rock hangn off the rotor head and still have full control.No matter the weight, configuration, power, hang angle, or paint condition, if you have control of the rotor and take off, you have control enuf to get down.You said he powered up, powered down, wagged the rudder, all to no effect. Wot happened to his primary control? Did his stick break?Machines are go,n to continue to spin in till everyone starts to fly the rotor, first.And for Christ sake, forget bout rotor bearing drag.If there"s that much drag from the rotor bearing it"s coz it"s bout to seeze, or has seezed, so spin,n in is the least of your worrys rite now.