Rotor Blades +/-

[bones]

Brian in the other thread you said;

Okay, that sounds more like it. I have the twisted and tapered , I hated them first off and got to love them. They are very diferent to the alloys.
The big problem I have with mine is that they dont carry a full load well on the odd hot day for some reason, I would like to see a smaller hub bar or is the tapered bit letting too much air out ?

So by that i take it that the blade do have a long hub bar, and that could be where your loosing some, and then you talk about the twist,,very interested in this, the thread on the yanky site sort of lost me abit, would you have a picy of the blades and or the hub bar, and anything else you want to throw into the issue
Thanks

[russ]

Bones, all robs blades are the same length, the hub bars are the determining "overall" disc size.

Over the yrs, i have flown many diferent types/ makes of blades........last yr when i was training at brizy, i was flying those tappered......twisted blades for the first time [ they were fitted onto the guys 2 seater ]
Mate...i loved them, am putting a set on me new 2 seater, guaranteed

i found they "hung in there" they had great lift, and they liked to fly quick using LESS throttle.

Downside...........bloody heavy, hard to "pat up", could give you some "interesting" moments, if you get low and slow amongst the trees [ low rotor rpm's ] then having to climb out over trees etc..........being heavy, you need some time to get em up to climb out rpm's

Personally, as for "working" blades.......i prefer light blades [ overall ] especially in tighter spots. Other pilots may have differing views re this..........each to his own

The day someone comes up with "the complete blade", he's going to swamped with orders

[bones]

Yep i hear you Russ, thou the AK's arent light either, and from what i saw they spin up pretty good,, i think mine is over rotored at the moment for gettin down and dirty, but just nice for cruising, so im still in two minds as to what i should be looking for, as was descibed in the yanky forum, sometimes the bigger blades for some reason just dont deliver the lift they should, now if it is to much rotor or just needing more time to spin up, i just dont know,, and funds being the way they are, i dont want to be doing the experimenting :evil_laugh:, but it has to be to my liking in the end so, i guess all i can do is try them and see.

[BeefBear]

So by that i take it that the blade do have a long hub bar, and that could be where your loosing some, ...


Mark, if you do the figures there's not a lot of effective lift being generated inside the first 6 feet of a set of rotors as the velocity is very much reduced when compared to the tip speed. And given the effects of reverse air flow on the down wind sector then there's a further decrease in the lift potential being generated.

[russ]

Ted, those blades bones has got are considerably wider at the root, with more pitch than normal blades as well.

they then taper [become more narrower] as they get to the outer tips
they also loose some pitch as they also get out to the tips

the idea is to get the inner section of the blade to generate lift, rather than just goin around, by then narrowing and lessening pitch at the outer ends, this controls the over excessive teetering that would occur as the whole blade is now working more efficiently.

Many yrs ago i tested a set of alloy "wide chord" blades..............the "lift" was absolutely unbelievable........but.......they teetered so hard, the shake was unreal. I managed to do 1 circuit.......phew

The more blade makers you talk to, the more you realise "they are all" perplexed with the constant downsides to getting the "magic" blade............but.......slowly they are getting there.

Even polishing blades real good has a reaction, just as bugs n shyte has a reaction to them.

I do know that certain blades suit certain machines/ horsepowers than other type blades. Great blades on YOUR machine could be ordinary on mine............mate, blades are weird things

[BeefBear]

Russ, I understand the purpose of the taper, however its the velocity of the rotor at the inboard section that is in question here. Changing the chord and camber of the rotor is definately the way to go for certain activities. The object here I believe is to construct a rotor which can perform within a range of rpm's, air density, temperatures, and enviornmental conditions.

To do so means from the chord profile view, the ability to maintain boundry layers for as long as possible. Once you get disruptions to this, the lift potential is disrupted.

http://selair.selkirk.bc.ca/aerodynamics1/Lift/Page2.html gives a reasonably clear definition and explaination of the lift formula. Should all else remain the same but your velocity changes, so to naturally does your lift being generated.

[russ]

Ted, agree with all you say here.

Getting back to those test blades, the maker has/had a contact at sydney uni, they spent huge hrs in wind tunnel with different profiles, different this, different thats, and they came up with the "magic" blade.

With great anticipation it was bolted onto my machine, as i said B4 it lifted like hell, machine flew a lot faster with a lot less throttle.................but shook like hell.

This was not expected to happin during concept stage. To proceed further with research was simply too many bucks, so it stalled.

Do know that the forces associated with "lead lag" were a big factor, do know that other blade makers overseas are at the minute installing different components to control this "lead lag" problem.

As i said B4 ........blades are weird things [ what suits your machine, can be ordinary on mine ]............much more techo than we think..........mind benders

[Aussie_Paul]

Ted, agree with all you say here.

Getting back to those test blades, the maker has/had a contact at sydney uni, they spent huge hrs in wind tunnel with different profiles, different this, different thats, and they came up with the "magic" blade.

With great anticipation it was bolted onto my machine, as i said B4 it lifted like hell, machine flew a lot faster with a lot less throttle.................but shook like hell.

This was not expected to happin during concept stage. To proceed further with research was simply too many bucks, so it stalled.

Do know that the forces associated with "lead lag" were a big factor, do know that other blade makers overseas are at the minute installing different components to control this "lead lag" problem.

As i said B4 ........blades are weird things [ what suits your machine, can be ordinary on mine ]............much more techo than we think..........mind benders


No they're not russel!!! The problem has been solved by Magni, and I will end up with the same on Firebird. Every part of the machine has to work in unison from the blade tip tp the control columnthe torque tube offset to the angle of the mast. That is why Magni will not supply blades to non magni owners for their Magni machine.

I am sure most of the experienced gyro pilots around have at some stabe tried a diferent brand/style of blade and found that they needed to change the trim tension. What that says is that the different blades behave differently to the previous blades.

Then idea that we all had years ago was that you can just throw different blades on and go fly. Well yes you can, BUT that will not guarrantee the most efficient performance out of those blades. I spent considerable time testing different torque tube off sets and other variables to achieve the best performance and stabiluity for one set/brand of blades. When I change to another blade brand I had to go through it all again.

If approx. 70 or 80 % is good enough then it does not mater much, BUT if you want, as I do for my Firebird to be as efficient and as stable as possible, I have had to conduct the testing to get it right. Just R & D for a particular result. Then, as a machine manufactured out of jigs and CNC'd parts, all will be and should fly the same.

Aussie Paul. :shiver:

[BeefBear]

Spot on Paul. Blade characteristics can change dynamicly with different flight conditions. Just ask helo engineers. And while manufacturer's are constantly trying to minimise the defects incurred in the manufacturering process, its still possible to obtain blades that are not matched correctly

[russ]

Hey paul..........see your little sign off man is rugged up and shivering a tad....

by chance, you wouldn't freezin ya tits off down your way....................bewdy :peace:

bleedin cold up ear to.............18 last nite........unreal aye............freezin :lol:

[Aussie_Paul]

Hey paul..........see your little sign off man is rugged up and shivering a tad....

by chance, you wouldn't freezin ya tits off down your way....................bewdy :peace:

bleedin cold up ear to.............18 last nite........unreal aye............freezin :lol:



Russ said, .............18 last nite........1.8 here!!!!!!!!!!!!

I have a head cold and flew 5 hours over the weekend in a single seat Domiunator style with a pod. Some people never learn. I got no sympathy at all at home last night!!!!!!! BUT I had a great time flying with friends, one who has not woken up yet and has a trike. A Tif next week might convert him.

Next week I begin training the guy from Canberra who bought the U beaut $58k gyro here in Ballarat.

Aussie Paul. :shiver:

[Sonnyj]

Paul
I got no sympathy at all at home last night!!!!!!!
Wellcome to the real world, and my house :friday:

All kiddin aside, I hope you get to fellin better soon.
Cheers
Sonny

[Brian]

Bones,
Pictures wont help you much as the difference between the tapered and twisted and straight blades are not all that visable.
Rob is probably the best bloke to get the facts from. The only thing I found with Robs hub bars are that they vary a bit which is disconcerting cause they should all be the same.
Anyway, going by what Birdy said about you being over rotored, I reckon a foot shorter, tapered and twisted would be the go but I would not sell your present rotors till you test the new ones !!

I was flying 28 ft AKs and have gone back to the Patroneys 26 ft 6 in and they are far far better for mustering, no comparision !!

[bones]

Ok Brian, so you went from 28' AK's to 26'6" Patroneys,,,, so do the Patroney's, can they handle quick full one side to the other side, with out shakin like a dog sh*tting razors, cause i was just talkin to a guy last night who flew a light weight gyro with 28' AK's and he said there was no shake side to side.. just wondering which way to go.

[Aussie_Paul]

Good morning people and Russell!! :wave:

IMHO Ak's don't shake because they have very little pitch, and hence less lift, hence don't have to work as hard.

FWIW I would be interested Ii I were a musterer to try some AKs with 1.5 degrees and say 2 degrees of pitch and see if they shake. If not, then the extra lift would be advantagous, but I reckon they would shake.

Aussie Paul. :shiver:

[bones]

IMHO Ak's don't shake because they have very little pitch, and hence less lift, hence don't have to work as hard

So why do they seem to be able to do the same job then, im getting more confused, the more i think about this subject..

[Birdy2]

Bones, all you gota do to increase the pitch/lift on blades that have a low pitch set in is to pull that stick back.

Pulln the stick back in pitch has the same effect as side t side as far as the blades are concerned, its cyclic input. [2 cycles per rev]
The faster they are spinin, the more cycles per second, more cycles per second means the pitch changes need not be as great to have the same effect.

[Brian]

Ok Brian, so you went from 28' AK's to 26'6" Patroneys,,,, so do the Patroney's, can they handle quick full one side to the other side, with out shakin like a dog sh*tting razors, cause i was just talkin to a guy last night who flew a light weight gyro with 28' AK's and he said there was no shake side to side.. just wondering which way to go.


Bones, quick side from side is probably more to do with the size of the rotors rather than how they perform, but in my case, yes, Robs blades are able to be pushed a lot quicker from side to side than the 28 AK's.
Personally, I like Robs blades better BUT the results can vary from one gyro to another eg, the same blades might be smooth as silk in one gyro and as rough as guts in another gyro. Rob built me a new hub bar, I sent him the blades but they were no where as smooth as the original hub bar! [Rob cant work it out iether :( ]

It would be interesting to give the AK's some more pitch and see what the results are, I reckon it would try them out for shake. I have a set of Ricks 27 fter's which need a new hub bar and cause Geoff builds his hub bar the same ar Rick did, I will give Geoff the job and ask him to pitch them at 1.5 or 1.8 and see what happens, I reckon originally, they had about 1.5 but I might be wrong!

[russ]

YEARS............back, most blade makers.....ie Rotorhawk,Benson,Jack Allens,Larkins............all made blades that you as the pilot could easily change blade pitch to SUIT YOUR applications.

Hub bar at each end had blocks top and bottom, with oversized holes. Blades had block at the ends with oversizes holes.
You butted these together, [ blade to hub bar ] inserted the joining bolts [4 ] and rotated the blade around the loose bolts, this allowed you to set whatever pitch you wanted, then you tensioned the 4 bolts up. Do the same to the other blade...................bingo, go flying.

Why this practise stopped beats me............

[bones]

hmmm yes Russ thats right, good point about those blades,,,,,, hmm you just got me thinking about that,,, might look at putting that attachment system, in these rotors cant be hard,then as you said just adjust it to suit.