Rotor Rooter
Dave Jackson
Perhaps an elongation this profile might be worthy of consideration.
The flight of winged seeds.
Particularly, with today's strong and light composite construction.
Dave
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Tapered Rotors-An experiment
- Thread starter Master Roda
- Start date
Perhaps an elongation this profile might be worthy of consideration.
The flight of winged seeds.
Particularly, with today's strong and light composite construction.
Dave
Master Roda
The Jedi
I gave you my opinion. If the 8" X 25' blade is a good choice for the gyro you're using, then I would like to see how a 0012 airfoil with a tapering 8" X 12.5" X 24' rotor would compare (with a 4' Hub-bar). I doubt that anyone would want to hand spin those blades anyway. Of course with all your experience, you would know better than I.
Why a 4' hub bar? Hand spinning should be reserved for light machiens that can't afford the weight of a pre-rotator anyway
I built a larger oven so I'm not limited by size anymore. The next test though won't be that large at the root, but will be bigger than the first test. I had a couple of ideas to try with our 7" materials (9/7x24') This airfoil is much thinner than our 8,8.5". I can actually change the airfoil and twist with them.
Of course the only problem with all of this testing is time and money. I'm glad Jim is so willing to let me do all of this. Without his approval none of this would be happening.
Master Roda
The Jedi
Thank you! That's a great graphical analogy.
Of course it would have to be modified for purposes of construction, but I like it.
Rotor Rooter
Dave Jackson
Jon
Here is the article that the image came from. It might make for interesting reading. http://www.unicopter.com/Temporary/The_Flight_of_Winged_Seeds.mht
Dave
Here is the article that the image came from. It might make for interesting reading. http://www.unicopter.com/Temporary/The_Flight_of_Winged_Seeds.mht
Dave
RotoPlane
Gold Supporter
I wasn't too clear, huh. I meant that blade size considering the use of a 4' bar (don't know what size you use). So one blade would be 10' long, or a 2' bar, one blade would be 11' long. I like .5" of taper/foot
.Oh, and thank you Jim!
Master Roda
The Jedi
Makes me want to glue 2 of those together and see what happens
I wonder what the reynolds would be in scale? What shape would it take in the size we need? Thanks for the link.Master Roda
The Jedi
I wasn't too clear, huh. I meant that blade size considering the use of a 4' bar (don't know what size you use). So one blade would be 10' long, or a 2' bar, one blade would be 11' long. I like .5" of taper/foot
Oh, and thank you Jim!
I see. We use a 3' hub for 8,8.5 and a 2' for 7". We have a 4' bar for 32', but it's heavy.
I'll try to get close to that .5" in the next one.
BEN S
Super Member
Hey Jon,
Hey Jon,
I don't know nuthin bout birthin no babies when it comes to this stuff, but if the outside section of the rotor is where the lift is formed for the most part, why not make the tips wide and flat and taper the blades down as they get closer to the hub bar? would look kinda funny I guess, also what would happen if your rotors were balanced, but NOT symmetrical? like the post I asked about stacking the prop blades so each blade is in clean air. Why couldn't you get all the benefits you want from a set of rotors by mixing two differnet sets. It would take an enourmous amount of trial and error to get the charicteristics correct for flight but tell Jim I thought long and hard about it and I'm willing to risk HIS ass for test purposes!
Taken one step further couldn't you have rotors where it was basically a thick stiff wire untill the ends where you would have the airfoil paddles attached? Not sure how you would spin them up.
Wait I got it!!!!Damn this is good here boy, I want royalties! a spool on the mast like a weedwacker that pays out the rotors/wire as it turns to the full length and retracts when needed for making a compact unit! Oh Snap, Evan had me thinking this aircraft design stuff was complicated, hell last week I came up with the energy souloution to power cars for free forever it was so simple I didn't even have to get a degree to think it up!
Anyway, I figure you are probably busy so don't worry about building them this week, maybe next week though.
Ben S
Hey Jon,
I don't know nuthin bout birthin no babies when it comes to this stuff, but if the outside section of the rotor is where the lift is formed for the most part, why not make the tips wide and flat and taper the blades down as they get closer to the hub bar? would look kinda funny I guess, also what would happen if your rotors were balanced, but NOT symmetrical? like the post I asked about stacking the prop blades so each blade is in clean air. Why couldn't you get all the benefits you want from a set of rotors by mixing two differnet sets. It would take an enourmous amount of trial and error to get the charicteristics correct for flight but tell Jim I thought long and hard about it and I'm willing to risk HIS ass for test purposes!
Taken one step further couldn't you have rotors where it was basically a thick stiff wire untill the ends where you would have the airfoil paddles attached? Not sure how you would spin them up.
Wait I got it!!!!Damn this is good here boy, I want royalties! a spool on the mast like a weedwacker that pays out the rotors/wire as it turns to the full length and retracts when needed for making a compact unit! Oh Snap, Evan had me thinking this aircraft design stuff was complicated, hell last week I came up with the energy souloution to power cars for free forever it was so simple I didn't even have to get a degree to think it up!
Anyway, I figure you are probably busy so don't worry about building them this week, maybe next week though.
Ben S
Master Roda
The Jedi
Your killin me Ben!
I like this kind of thinking though because it spurs ideas.
Depending on how much freedom I get with this project, I just might try something close to that flying seed
I like this kind of thinking though because it spurs ideas.
Depending on how much freedom I get with this project, I just might try something close to that flying seed
down under
Newbie
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- 281
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- Charleville Australia
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- gyro single seat
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- 5300
The best blade would be one with the minimum amount of compromise.
Low cone angle for better flying characteristics and minimum stickshake.
Spread the lift on the outer half/third of the blade for better efficiency and lower cone.
No lift at the inner third as this area has the greatest dissymantry of lift in forward flight, but use as driven area for vertical descent.
Keep rpm up for fast controls.
The best blade? Minimum engine rpm, O stickshake, fast control, good lowspeed capability,
High speed capability - perhaps two designs one maximum cruise of 80knt another maximum cruise 120knt.
I like the seed shape for a rotor.
Disc loading 1.5lb Blade loading 35lb
Low cone angle for better flying characteristics and minimum stickshake.
Spread the lift on the outer half/third of the blade for better efficiency and lower cone.
No lift at the inner third as this area has the greatest dissymantry of lift in forward flight, but use as driven area for vertical descent.
Keep rpm up for fast controls.
The best blade? Minimum engine rpm, O stickshake, fast control, good lowspeed capability,
High speed capability - perhaps two designs one maximum cruise of 80knt another maximum cruise 120knt.
I like the seed shape for a rotor.
Disc loading 1.5lb Blade loading 35lb
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down under
Newbie
- Joined
- May 8, 2009
- Messages
- 281
- Location
- Charleville Australia
- Aircraft
- gyro single seat
- Total Flight Time
- 5300
Another thought I have had for some time is to more evenly distribute the blade loading.
The area of blade near the tips that generate the most lift will be operating at very high loading.
Possibly positive twist to the 2/3 radius then negative twist to the tip. Rather than having the lift and loading curve up to a peak near the tip, have a flat line of lift and loading on the outer third.
Also tip weights that can be quickly changed. No tip weights for throwing it around, add weights for smooth cross country.
The area of blade near the tips that generate the most lift will be operating at very high loading.
Possibly positive twist to the 2/3 radius then negative twist to the tip. Rather than having the lift and loading curve up to a peak near the tip, have a flat line of lift and loading on the outer third.
Also tip weights that can be quickly changed. No tip weights for throwing it around, add weights for smooth cross country.
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Master Roda
The Jedi
Thanks Peter.
I like the seed shape too. I'll see what I can do to build it, or something close anyway
I like the seed shape too. I'll see what I can do to build it, or something close anyway
Rotor Rooter
Dave Jackson
Nature usually gets things right over hundreds of thousands of years of experimentation. I suspect that the 'seed shape' is the optimal one for vertical descent; only. The seed's horizontal movement comes only from the wind that pulled it off of the branch.
The pros and cons of a wide chord was fought out between the French and the United States a couple of years back. The French claim that Paul Cornu developed and flew the first helicopter in 1907. Dr. Leishman took the American side and attempts to prove through calculations that Cornu's craft could not have been the first to fly. '2007: Centennial of the Helicopter?'
It appears that Dr. Leishman used conventional rotor calculations and perhaps they are not valid for the unusual Cornu airfoil.
It should be noted that Cornu's craft had blades with very wide chords, similar to the seed shape, but without the need for a 'Driving region'
As Peter mentions, the seed profile, and other characteristics, will have to be increasingly modified as the design cruise speed of the craft is increased.
Dave
The pros and cons of a wide chord was fought out between the French and the United States a couple of years back. The French claim that Paul Cornu developed and flew the first helicopter in 1907. Dr. Leishman took the American side and attempts to prove through calculations that Cornu's craft could not have been the first to fly. '2007: Centennial of the Helicopter?'
It should be noted that Cornu's craft had blades with very wide chords, similar to the seed shape, but without the need for a 'Driving region'
As Peter mentions, the seed profile, and other characteristics, will have to be increasingly modified as the design cruise speed of the craft is increased.
Dave
Master Roda
The Jedi
It seems a definite compromise is in order.
An airfoil cannot be the same through the entire length of the blade and still be efficient. So, at each section, a determination of the correct chord and airfoil is needed.
Thanks Dave. I appreciate your input.
An airfoil cannot be the same through the entire length of the blade and still be efficient. So, at each section, a determination of the correct chord and airfoil is needed.
Thanks Dave. I appreciate your input.
Friendly
Platinum Member
Jon,
It has been over 3 months since the last post on these rotors. What were the numbers? How do the tapered compare to the standard rotor, or did I miss the post somewhere? I am still interested in the outcome
It has been over 3 months since the last post on these rotors. What were the numbers? How do the tapered compare to the standard rotor, or did I miss the post somewhere? I am still interested in the outcome
I'm kinda curious too....
scottessex
Sling-Wing Pilot
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- central, ga
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- Dominator 582
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I think He's holding out on us.
Master Roda
The Jedi
Sorry guys, I thought it was clear in another thread.....
The tapered blades have definite benefits over "our" standard rotor. They have a great stick feel (hard banking,etc) and vertical descents are slower.
I'm not going to reproduce them just yet. I'm working on another version that should produce even better results. The problem is that I'm really busy with another project (SCII) and the regular blade orders. So it will be very long time before they come to market. Although if someone REALLY wanted a set, I'm sure we could work something out
The tapered blades have definite benefits over "our" standard rotor. They have a great stick feel (hard banking,etc) and vertical descents are slower.
I'm not going to reproduce them just yet. I'm working on another version that should produce even better results. The problem is that I'm really busy with another project (SCII) and the regular blade orders. So it will be very long time before they come to market. Although if someone REALLY wanted a set, I'm sure we could work something out
scottessex
Sling-Wing Pilot
- Joined
- Nov 12, 2003
- Messages
- 11,244
- Location
- central, ga
- Aircraft
- Dominator 582
- Total Flight Time
- 200+
What you're busy!?
I hear you brother!
I hear you brother!
Friendly
Platinum Member
Sorry guys, I thought it was clear in another thread.....
The tapered blades have definite benefits over "our" standard rotor. They have a great stick feel (hard banking,etc) and vertical descents are slower.
I'm not going to reproduce them just yet. I'm working on another version that should produce even better results. The problem is that I'm really busy with another project (SCII) and the regular blade orders. So it will be very long time before they come to market. Although if someone REALLY wanted a set, I'm sure we could work something out
Jon,
you promised us numbers. I can appreciate you are not ready to produce the blade, I just want to know the results of your testing in numbers. This is not picking on you. I also want the numbers from the Time to Climb contest as the rules outlined the qualifications to enter., you know weight, thrust, rotor rpms. etc.
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