Dragonwings Vrs. Sportcopter Results! [Archive]

GyroRon

07-25-2004, 06:05 PM

Okay it is done. What a pain in the butt to do this today cause I was tired and it was hot out but I did fly my 24 foot Dragonwings and did a few tests to record results and them swapped blades and did the same tests over with Barrys 24 foot, 7 inch chord sportcopters and here is what I found.

First off, I made sure to start both testing sessions with full tank of fuel. I also used a person on the ground listening to the radio to record my results as they unfolded so as not to mess up the numbers. My gyro was trimmed out for straight and level at 65 mph with the dragonwings and I made no changes to the gyro when I put on the sportcopter blades. I did have to re shim my teeter hats cause the sportrotors center section the teeterbolt goes through was thicker than on the dragonwings and my hats were bottomed out on the blades and not on the towers until I shimmed them. The temp and winds and so on were very close to the same since I did both runs right back to back. All the tests were done over the runway in the same place and same directions and so on to be as close to spot on as practical.

First observations was the Sportcopter blades were Smoother than my Dragonwings, but not by much. I know my Dragonwings are ever so slightly out of track and I believe if I got them tracked alittle better the stickshake would be equal between the two brands.

Also the Sportcopter blades flew noticeably faster in rotor rpm than the dragonwings.

And also the Sportcopter blades had a heavier feel in the stick from side to side, like it took more pressure to change direction.

Also the Sportcopter blades needed a good amount more trim pressure than the dragonwings, It felt if I had let loose of the stick the gyro would be flying at 100+ mph so I had to hold back pressure on the stick the whole time - Or I would have had to reset my trim spring further down the mast but didn't.

Lastly the Sportcopters seemed to have more "float" in the landing mode. I could come in ridiculously slow and hold it off the ground to a landing at speeds I know the Dragonwings would have quit on me at.

automan1223

07-25-2004, 06:58 PM

Ron you must have a tape worm or something. You are never tired.

You are like the energizer bunny......

question

you said the sport rotors felt heavier in the stick side to side, how was stick shake in turns. ?

how was lift off distance ?

:cool:

gyromike

07-25-2004, 07:02 PM

Ron,

Did you record:

Engine RPM at trimmed speed?
Rate of Climb?
Rotor RPM?

Etc.
Etc.

GyroRon

07-25-2004, 07:39 PM

Sorry guys for the pause in my report. I had to eat my frozen Pizza dinner! :D And Todd Powell gave me a ring and we were on the phone for a while talking gyro stuff, so now maybe I can finish my post.

GyroRon

07-25-2004, 07:40 PM

another view of the blades

GyroRon

07-25-2004, 07:44 PM

So back to the comparo.....

One of the things I did first was to weight the blades. Easiest way to do that was to step on my bathroom scale and weight myself - must have been too much Mcdonalds and not enough walking lately :eek: - and I was 208. Then I picked up the Blades, one set at a time, and weighted myself with the blades in my hands. The results were the Dragon Wings added 46 lbs to my 208 and the Sportcopters added 51 pounds. So the SPortcopters are only 5 pounds more....

GyroRon

07-25-2004, 08:10 PM

Now I need to mention that my Rotortach is not reading correctly. The tach runs through my EIS system and uses the same pickup unit used on most rotor tachs, but the system also uses a special tuned box to turn the signal the pickup unit puts out to something the EIS system can use to display the speed. Apparently EIS didn't program the box right and my rotor speed reads I am thinking about half of what the true speed is. Otherwise the tach reads consistent and without error. So my rotor rpm readings are not true rpms but they do reflect the differences in the two blades. As a side note, during pre rotations my rotor tach will show about 90-95 when I know the right RRPM is at or a little higher than 200 true RRPM.

Then I ran the numbers with the Dragon wings. And then right after I swapped the blades and refilled the tank I ran the SPortcopters. Here is the tests I performed and the results.

DRAGON WINGS:

Top speed at wide open throttle held steady at 20 feet above the runway for the length of the runway - 90 mph, 6700 engine rpm, 187 rotor rpm

Airspeed indicated at 6000 rpm holding altitude, 500 AGL - 62 mph, 178 rotor rpm

Airspeed indicated at 5500 rpm holding altitude, 500 AGL - 55 mph, 178 rotor rpm

Minimum power to maintain altitude, 500 AGL - 5300 engine rpm at 25 mph

Minimum power to maintain altitude keeping airspeed at steady 55 mph, 500 AGL - needed 5100 or higher engine rpm

Rate of climb for 1 minute, started by flying down the runway at 100 feet AGL at 60 mph at cruise power setting and then go to full power and hold 60 mph steady for the entire climb, note altitude gained after 1 minute of climb - 600 Feet per minute

Time to climb to 1000 feet, started by flying down the runway at 100 feet AGL at 60 mph at cruise power setting and then go to full power and hold 60 mph steady for the entire climb, note total time taken to reach 1100 feet AGL - time to climb to 1000 feet was 110 seconds

Last test was a vertical decent test, gyro was taken to 1600 feet AGL and put into a vertical decent straight down and held there. Timed the drop from 1500 feet to 500 feet - time to vertical 1000 feet, 36.47 seconds with a rotor Rpm of 167

SPORTCOPTER:

Top speed at wide open throttle held steady at 20 feet above the runway for the length of the runway - 85 mph, 6675 engine rpm, 187 rotor rpm

Airspeed indicated at 6000 rpm holding altitude, 500 AGL - 70 mph, 185 rotor rpm

Airspeed indicated at 5500 rpm holding altitude, 500 AGL - 60 mph, 183 rotor rpm

Minimum power to maintain altitude, 500 AGL - 5300 engine rpm at 28 mph with 174 Rotor Rpm

Minimum power to maintain altitude keeping airspeed at steady 55 mph, 500 AGL - needed 5250 or higher engine rpm

Rate of climb for 1 minute, started by flying down the runway at 100 feet AGL at 60 mph at cruise power setting and then go to full power and hold 60 mph steady for the entire climb, note altitude gained after 1 minute of climb - 600 Feet per minute

Time to climb to 1000 feet, started by flying down the runway at 100 feet AGL at 60 mph at cruise power setting and then go to full power and hold 60 mph steady for the entire climb, note total time taken to reach 1100 feet AGL - time to climb to 1000 feet was 106 seconds

Last test was a vertical decent test, gyro was taken to 1600 feet AGL and put into a vertical decent straight down and held there. Timed the drop from 1500 feet to 500 feet - time to vertical 1000 feet, 38.19 seconds with rotor Rpm of 171

GyroRon

07-25-2004, 08:34 PM

So my basic opinion on the two blades performance wise is it was close. Really close. The Sportcopters weren't as sporty feeling due to the higher force needed for side to side movements. But the sportcopters I feel were the better blade overall. The allowed a higher cruise speed at a given power setting, they took longer to come down in a vertical descent, and they seemed to let you just about come to a hover in the landings without pooping out and dropping you as the Dragons will do as they slow down. The Sportcopters seemed very happy to fly slow and it is hard to put this feeling in words, but they just seemed like they were much more forgiving in landings since they kept you up till you made them stop flying....

Would I buy Sportcopters for my next set of blades? I don't know. Depends on a lot of factors. I personally am not one to wait around on stuff, If I want to buy blades I want them ASAP not months later, but if I were building a gyro and didn't need my blades till I am done months later then waiting is no big deal. I also don't think the difference between the blades is worth a huge increase in price for Sportcopters, a few hundred is reasonable but not more than 4-5 hundred IMHO.

I like both blades and think either is a good choice. I say the winner comes down to what you want out of the blades.

I am hoping some of the guys like Chuck Beaty can take some of my numbers and show us the science behind the numbers and the differences. For instance the Sportcopters overall flew faster by at least 5-8 RRPM as shown on my incorrect reading rotor tach.

There is also the possibility that on someone elses gyro the differences between these two blades could be much further apart than they were for me. And or there is the possibility that I had too much error in my tests, but I tried real darn hard to do Exactly the same tests for both blades.

So the way I see it the Sportcopter has the better fit and finish, slightly smoother stick, better float, higher cruise speed at given rpm. but they cost more, and they take a while to recieve when you order them.

The Dragon wings are lighter, flew faster at top end, were lighter on the stick and had a sportier feel, They also seemed easier to stay at a given airspeed without as much corrections as the Sportcopters needed. They are cheaper by at least a few hundred bucks, they are in stock ready to be shipped if kept polished they look pretty darn good too!

Here is a first..... A dominator with Sportcopter blades on it! :eek: :D

GyroRon

07-25-2004, 08:35 PM

Last pic, one more of the Sportcopter blades on the Dom.

07-25-2004, 10:15 PM

Ron,

Great post. You've always expressed a preference for Dragon's, but you've got the experience to do that. This was a pretty straightforward comparison. I like the raw data.

Thanks for putting in your time to do this.

PW_Plack

07-25-2004, 10:38 PM

Ron,

Thanks for the work, and great posts. I wonder whether getting the Sport Rotors pitched to produce the same RRPM as the DWs would have made it closer at the top end.

gyromike

07-26-2004, 06:09 AM

Thanks for the info, Ron.

Mike Morgan and I are wanting to do the same type of tests. We have Dragons, Skywheels, Bensens, and Rotordynes to test. I'll need to mount a rotor tach on mine first.

It's just too damn hot for that foolishness right now. http://www.dodgetrucks.org/forums/images/smiles/icon_rolleyes.gif

GyroRon

07-26-2004, 06:17 AM

Paul, there is no way to adjust pitch on either of these blades.

Automan 1223, there was nearly no stick shake at all with the sportcopters and that includes tight turns. My dragonwings are visably out of track. I have already shimmed the blades and got them almost perfect tracking wise, but still need like one more shim to be perfect. Right now there is only the slightest hint of stickshake, just a hair more than the sportcopters. Both are a far cry smoother than the blades in alot of the gyros I have flown!

Wingnut, thanks.

I will say that I still favor the Dragons, but if you want to spend a few bucks more and wait a while, I would buy the Sportcopters. I REALLY like the epoxy painted blades, the Polished aluminum is a bitch to keep clean and looking good. The Epoxy blades wipe clean with a damp towel.

GyroRon

07-26-2004, 06:18 AM

Mike I look forwards to that comparo. To be apples to apples all four sets ought to be the same length.

ahancock

07-26-2004, 06:23 AM

Ron,
You might want to check your EIS manual. you can adjust the scaling for the rotor
tach and get it to read correctly.
Alan

Chuck Irby

07-26-2004, 06:28 AM

Good testing, and great report, Ron. Thanks for going to that trouble.

GyroRon

07-26-2004, 06:30 AM

Alan please tell me how to do that!

scott heger

07-26-2004, 11:47 AM

Ron, thanks for all the hard work to do the test. Nice to see a side by side comparison under same day/weight conditions. Since my SportCopter has no trim springs(nor needs them), it was interesting to see your comments about the stick pressure. What is a non-issue on one gyro is a small problem on another with certain blades. I have 25X8 Sport blades, and find my machine slightly overbladed for light weight cold sea level flying, but great for summer high density flying. They are a little slow to spin up compared to the 25X7 ones, but absolutely "float" on the bottom end of a landing. What could be a hard landing in gusty winds never is with the bigger blades. But as you mentioned before, the nicest feature is the epoxy white blade coating. I absolutely despise polishing bare aluminum every few months. A wet towel, a little car polish, and it is now a 10-15 minute job.

Scott Heger, Laguna Niguel, Ca SportCopter N86SH

MikeBoyette

07-26-2004, 02:53 PM

Everyone,
Don't forget that a polished blade has to be made with much more care since it has no paint to camoflauge any imperfections.

GyroRon

07-26-2004, 03:45 PM

Steven if you were closer I would love to try them out on my gyro.

Scott H, your welcome. It is something I have been wanting to do for a while and just got around to it. I went water skiing on Saturday and my ass was slap wore out by Sunday afternoon when I was doing all this blade swapping. Today I could barely walk!

Mike B, you do have a good point. Dragon wings come from Ernie with a flawless appearance and no blems. It just sucks that they don't stay that way for long!

I also want to add that I used to like the Sportcopters over Dragon Wings due to the " adjustability " of the hub bar for tracking and centering the hub bar in the towers. Now that I have worked on fine tuning my Dragon wings, and remembering the tweaking I did on my Sportcopter blades I had on my first gyro, I like the ease of adjusting the Dragon wings much much more. It is foolproof to do tracking and side to side adjustments on Dragons.

MikeBoyette

07-26-2004, 04:18 PM

Thanks Ron,
I am glad to see that you are able to see the good in both sets of blades and give your un-biased opinion. I will run the paint thing by Dad when he gets back. In the past he has expressed the opinion that painting blades is not an option, however if he had enough customers that wanted them that way he may change his mind. The one thing I can say about keeping polished blades looking good allows you to keep a good eye on you blades,and if there is a problem it is spoted early. Painted blades would allow one to pay less attention to the blades. Also I don't care if they are painted or polished they should be handled and cleaned before each days session. Bugs are murder on blades.

GyroRon

07-26-2004, 06:48 PM

Mike I think they are both good blades and both have a few advantages over the other making it almost a wash in the end. Will I run out to buy a set of Sportcopter blades for my gyro now? No.

But I can always borrow Barrys! :)

ahancock

07-27-2004, 05:30 AM

Ron,
I'll have to see if I can find my manual. How many teeth does your ring gear have? That
is the variable needed to scale the tach.
Alan

automan1223

07-27-2004, 08:30 AM

Mike, Your dad is right and while white on the blades is nice it will never last forever. I agree that careful attention to blades is paramount to safe operation. There is no such thing as maintainance free in the experimental world.

If there was some clear coating or cooking spray or something that would make the bug guts come off a lot easier then it might be worth looking into.

Ron, If your rotor rpm was considerably higher on the Sport rotors would that not account for float time at the slow end ?

THats a matter of blade pitch, rotor inertia and aero drag. I would base float on same rotor rpm and then suggest that the sports had more on the landing endin of things.

2 cents

MikeBoyette

07-27-2004, 03:58 PM

Johnathan,
I honestly think the higher RPM is the Magic that makes the Sport Rotors what they are. I believe that if you were to slow them down to same RPM they would probably shake just as much if not more.

scott heger

07-27-2004, 04:38 PM

MIke B, Your dad makes great blades, no doubt. Many people that own them like them very much. I have not flown Dragon Wings before, so I can not say one is better than any others. However you are far from unbiased in your opinions. In your statements Dragon Wings are ALWAYS better than some other Company's blades, no matter what they are up against. Have you flown all the different brands that you find somehow inferior? Can you give us all the test data you have accumulated to come up with your results? Until you can provide all the data to prove that, you might want to mention the "minor" fact that you really have not compared all the possible blade combinations .There are several good blade manufactures out there, Dragon Wings being one of them. Each type has certain advantages and disadvantages. To say that the paint is going to come off, well thats just bullsh*t. I have 75 hours on my blades, and they are not missing any paint whatsoever. No dings, scrapes,chips, nothing. When painting any object, a good paint job is always reliant upon the prep work. Don't you think that others' can be and are as careful as your dad's Company? You ever see how the other Companies make blades and what pains they take to make their blades right? Of course not. It is alot more work to prep and paint blades correctly, than just buff and polish bare aluminum. They did this because many customers wanted them this way. They are so much easier to keep clean. I will never own another set of bare metal blades again....period. Paint has come along ways in durability since your dad started in the business, he may want to investigate some of those options.

Scott Heger Laguna Niguel, Ca N86SH

automan1223

07-27-2004, 05:05 PM

The size of the blades and the overall shape is prob the same. However the weight and bending / flex and a whole lot of other factors come into play when trying to compare blades. I do think that the hub bar for the dw's could use some refinement for adjustments it just looks too simple to me and the blade straps could use some more material in my opinion but i can say that I have flown them on the 2 pl air command and I would not change a thing how they fly on that machine with that setup. I dont think they could be improved upon. Great lift, float, flare, smooth. And remember I am a BIG guy, so they got a workout.

Jonathan

GyroRon

07-27-2004, 05:11 PM

I don't think Sportcopter " paints " the blades. I think they coat them with some special Epoxy coating. I can say I have banged Barrys blades into the hangar and scraped them on the gravel rock in my hangar and generally gave them hell and they still look just as nice as the day they came out of the crate.

I would pay a little extra to have this coating on Dragonwings if it was offered.

Udi

07-27-2004, 05:17 PM

…I honestly think the higher RPM is the Magic that makes the Sport Rotors what they are…

There is no magic, Mike. I am sure you know all that, but if the blades are turning faster it is because they create less lift at a given RPM. The blades turn as fast as they need to support the weight that they carry. Generally speaking, same length-faster turning blades are less efficient because the have more drag.

Faster-turning blades require less undersling. If your teeter towers don't have enough undersling, you get 2-per-rev shake. Mount faster turning blades (i.e. shorter or less efficient ones), and the 2-per goes away.

As we all know, there are other causes for stick shake, like static and dynamic balance and tracking, but they don't go away with RRPM. Ron, are you using the highest hole in the teeter block for your teeter bolt?

Question - are the Dragon Wings and Sport Copter blades constructed the same way? I know they use different airfoils and finish etc. but, other than that, are the spar/skins/glue/end-weight construction technique identical?

Udi-

GyroRon

07-27-2004, 05:32 PM

The dragon wings have slightly less shake in the top hole on the teeter towers. I tried the lower bottom hole and it was like I said slightly more shake.

The Sportcopter blades only allow you to use the bottom hole in the towers - Standard Bensen Height -

the Sportcopter blades also have the twist for blade pitch done directly in the hubbar, where as Dragon wings have their twist in the blade itself.

I lost 5 MPH in top speed wide open throttle with the sportcopters but the indicted RRPM was the same on both blades I believe. But the Sportcopters seemed to allow me a faster cruise speed at a given throttle setting in the 5500-6000 RPM range.

MikeBoyette

07-28-2004, 12:58 PM

Thanks Udi,
I was being a smart A** when I used the "magic" word. I understand all of that. The mentality we are dealing with is the same as people buying a Caddilac pick up truck as aposed to a Chevy. It costs more and has more bells and whistles so it has to be better.
Scott, I have been involved with gyro's since I was in diapers. I am now 32 about to be 33 in September. I have never flown another set of blades. I am biased. I say this I challenge you to try a set of DW and tell us what you think. I have seen many people come back from flying DW for the first time and I can count on one hand the ones who were not all smiles.

automan1223

07-28-2004, 02:19 PM

I think Jim Vanek is using Imron paint. It is what they use to paint jetliners. It sticks at 5-600 mph. it will also kill you quick if you handle it without professional air breathing equipment.

scott heger

07-28-2004, 03:29 PM

Mike B, you want to send a set to California, I'll be happy to try them. Each blade has some trade off. I have given up some inital spin up performance(from 25X7 to 25X8), and a slight bit of smoothness, for forgiving / floating heavier blades that are low maintance and give better "cruise" . Your Dad is a very important part of the industry, as few good blade makers exist, I hope he and you prosper well. Just don't close your eyes to the fact that just because others do it a different way, it is not necessarly inferior, they just might be better and worse in some ways.

Scott Heger, Laguna Niguel, Ca N86SH

cgmg

07-28-2004, 04:15 PM

Due to damaging our original McCutchens, we switched to Dragon Wings. After the initial scare of flying them the first time(totally different feel from McCutchens, which Ernie duly warned me about), I love them.

Based on Ron's testing, the two brands of blades seem to be pretty close in performance. Speaking personally only here, I would be hard-pressed to look at anything else to fly. The price was real reasonable, delivered in less than two weeks, fly them right out of the box, and Ernie has been more than patient with me when I called with questions regarding some of the things I have managed to do with my blades.

The which-blade-is-better debate seems to boil down to a matter of personal opinion, and to some extent, how well your wallet is padded.

Ernie will have my business unless we switch to a heavy 2-place.

MikeBoyette

07-28-2004, 04:24 PM

Scott,
Come to ROC, BD's or next years national fly-in and introduce yourself to either my Dad or me(if I am there) and we'd be glad to let you try a set. As for my Bias understand this I am not or have I ever been a financial beneficiary of my Father and Stepmother's company. I am biased because, unlike Jim who got investors to back him and bought all kinds of expensive machinery, my Family has made Rotor Flight Dynamics Inc. what it is by themselves. This of course includes family friends such as Chuck Beaty, Dick DeGraw, Llyod poston, Charlie Presnell, And many more. My Dad had a dream when started manufacturing rotorblades over 14 years ago to be the best. With over 1200 sets of blades since then I think he's made it. Also maybe Chuck or Udi can elibortate as to why DW's are more efficient. My Dad did not simply copy another brand of blades and make them pretty. He made something totally new to the gyro blade industry. And as Forest Gump would say "That's all I'm gonna say bout that".

PW_Plack

07-28-2004, 04:30 PM

Isn't it great to have two high-quality choices in rotorblades, actual differences in features between them, and a worldwide forum to discuss it all? I'm laughing, because many product categories have internet forums in which users are trying to out-do each other with stories of how the one they chose is worse!

How tough is that paint? Mike, didn't you guys dissect a broken set of 30-foot Sport Rotors last year? I believe Chuck B. said he had to soak them overnight in solvent to get through the paint, and declared the workmanship "first rate."

I think these are both great products. I like the idea of accountability from a manufacturer when I have a problem, so if I bought a Dominator, I'd want Dragon Wings, and if I bought a Sport Copter, I'd get Sport Rotors. If I compiled the ten most exasperated moments in my life, eight of them would be occasions when manufacturers (or phone and internet companies) have blamed problems on another vendor on the project. If I have unsatisfactory performance, it's worth a few bucks in at purchase time to skip the whole finger-pointing stage.

Now, if I built an Air Command or Brock machine, hmmm...

Rando

07-28-2004, 05:05 PM

Mike Boyette, do you know what kind of cleaner and polish your Dad uses or recommends for aluminum blades?

ben

07-28-2004, 05:26 PM

randy
what kind of pitch do you have on that subie motor and what kind of rpms do ya get? thanks ben

gyrodude

07-28-2004, 05:32 PM

I used to paint sailboats down in the Florida Keys with Imron. It is magic stuff but very fatal if you breathe it. Once it cures pretty much nothing will scratch it. We could remove the bumpers from the side of a boat when tied up at a pier and let it grind away with nary a scratch.
It is available from marine supply stores and is not cheap but is not difficult to work with and gives a slick finish.

Rando

07-28-2004, 05:35 PM

randy
what kind of pitch do you have on that subie motor and what kind of rpms do ya get? thanks ben

I didn't set it up, Ernie Boyette did so he would be the expert to ask. Sorry.

MikeBoyette

07-29-2004, 03:03 AM

Randy,
He uses canuba( not sure of the spelling) car wax by kit. Also he recomends alcohol to clean the bugs off.

Chuck Irby

07-29-2004, 04:09 AM

Mike, I wondered where the idea came from to use alcohol. I ran out once and had to use water. I decided that water worked as well as alcohol, if not better.

Now that your dad is back, please ask him about my rotor head problem, balance or out of round???

scottessex

07-29-2004, 04:19 AM

Mike, I think that you mean carnuba wax, it is a pure wax with no abrasives or solvents.

Gary, yes Imron is good stuff, but ever since they took the lead out back in the late 1980's it is not the same.

And yes Imron fumes are nasty, as are any from the new cross-linked paints, they contain isocyanates. You must use a good quality respirator.

What I would do is use a self etching epoxy primer, then wet sand, to keep the buildup down to a couple mils. Then use arcrylic urethane base coat to apply the color, just enough to get the color, and cover the primer, then use an arcrylic urethane high solids clear coat. Wet sand the clear coat with 1500/2000 grit wet paper, and then buff to a high gloss glass-like finish. Just like a high quality paint job on a motorcycle.

Just my $0.02

GyroRon

07-29-2004, 04:30 AM

If you wax the blade then wipe clean with Alcohol, the Alcohol will wipe away the wax too! I agree with chuck, A rag dampened with water works pretty good. I also have used and had good results with Armorall - spray it on and then wipe off all the bugs and crud and leaves the blades shiney and protected

Ralph

07-29-2004, 05:44 AM

We had our original Rotordynes painted in a professional shop using Imron back in 1989. Except where it was gradually eroded at the blade tips, due to the high-speed airflow, the finish remained flawless for12 years of flying. The blades were impervious to handling, the finish did not crack or chip, and bug guts cleaned up easily.

Ralph

Aussie_Paul

07-29-2004, 06:44 AM

I drink the alcahol and use water to wash the blades!!!!!!!!!!!!!1

Aussie Paul.:)

Chuck Irby

07-29-2004, 06:52 AM

But only after flying, not before. Right AP? :D

C. Beaty

07-29-2004, 04:33 PM

Well Ron, your findings that performance of Sportcopter blades and DWs is roughly equal has certainly made you the fair haired boy of the Vanek groupies and their ilk.

When Matt Pearson reported his findings from a similar comparison, with functioning instruments no less, that DWs gave a 1,000 fpm rate of climb Vs. 600 fpm with Sportcopters, the howls from that group almost made it seem that he had sodomized Mother Teresa. Had he dared to show his face on the West Coast, he most likely would have been tarred and feathered at the least.

It is almost impossible to cram so much junk in a single place gyro with 24' DWs and 582 Rotax that it will not produce a 1,000 fpm rate of climb at sea level.

Higher top speed and less power to maintain altitude with more power required in-between? No way.

When someone lays out a stack of $1,000 bills to have a go at FIA records for time to climb and absolute altitude, he wants the best possible equipment; verified with dry runs.. Win, lose or draw, the money is gone.

Andy Keech's accomplishments stand alone. Altitude: 26,408'. Time to climb to 6,000 meters: 24:28. That's an average rate of climb to 20,000 feet of about 800 fpm.

Equipment: LittleWing Autogyro, turbocharged Rotax and DW rotors.

Heron

07-29-2004, 05:25 PM

Carnauba (car - nah - oobah)
Brazil helping the gyro movement . . . .hihihihii :)
Heron

GyroRon

07-29-2004, 07:54 PM

Chuck I too remember Matt testing the two blades and he came to the conclusion the Dragons were better. I looked for his posts about but couldn't find them. I did find this post from his though....

" --------------------------------------------------------------------------------

I indeed initially had the new 23 ft Sport Rotors before I bought a set of 23ft DWs for Super Fly. The Sport Rotors were by far the smoothest blades I have ever flown, HOWEVER, the DW's gave better than 100 fpm increase in climb, 7 mph speed increase and would allow the gyro to fly at a slower minimum speed. The BIGGEST difference besides the fact that you can get the DW's immediately, is the overall "feel" of the DWs over the SCs. The DWs give instantaneous response and "feel" as though they are spring loaded. Just look at the video of the Monarch dropping in from over 10 feet!! They are so predictable in how they respond to pilot input
Jim Vaneks did not believe my findings and sent me another set of blades to try which he "tweaked" and also took out some tip weight, but it made no difference. I am now a DW fan for life!
Mike, any word about adding another degree of twist?"

If you look at my tests I am saying about the same thing Matt said in the quote above. That the dragonwings were more sporty feeling and that the dragonwings gave me a faster top speed.

I am more than willing to admit my testing could be off. I went into this unbiased and just wanted to see if there was much difference between the two blades. And there is alot of difference between the two. Like I said the sportcopters turned faster, the sportcopters had a heavy feel compared to the Dragons, and the Sportcopters required alot more trim pressure or back pressure on the stick than the Dragon wings.

Performance wise it was very close. I will be the first to admit, the numbers were so close, that the margin of error in my testing could make one set marginally better than the other when if tested under perfect conditions the results might favor the other blades. But I can tell you that the rate of climb and time to climb to 1000 feet Tests were done EXACTLY the same and if there is any Error in my findings there then it is too small to make much difference. With either set of blades at full power at a constant airspeed of 60mph the rate of climb was right at 600 FPM and the time to 1000 feet was only a few seconds apart.

Look I will be glad to do any type of testing you want me to do between these two blades. This is the first time I have " tested " any blades, so I was not sure of what things I could do that would show which blade was better. Give me some ideas and instructions on how to do what you want me to do and I will do it.

I will also have both sets of blades at ROC if you or Ernie or anyone else more experienced wants to do the tests.

C. Beaty

07-29-2004, 09:33 PM

Whatever the numbers, Ron, Matt reported the DWs out performed the SCs in every respect and got slammed pretty hard for so stating. That stuff was originally posted on Norm's conference and is gone forever, I suppose.

He was accused of not being a professional test pilot, not having certified instruments, etc., etc.

Everyone I know of who has done side by side comparisons preferred the DWs. Jake Jacob comes to mind as well as a couple of Carl's Schneider's pals in Iowa.

And the reasons are no mystery. The SCs aren't 1/4 chord balanced and have a strong nosedown pitching moment which produces the heavy stick and need for more trim spring tension; at least the 8 1/2" blades. I haven't had the opportunity to run the 7" blades on an airfoil program.

If anyone has a set of crashed 7" SC blades with a few uncrumpled inches, I'd love to run them and publish the results.

GyroRon

07-30-2004, 04:55 AM

Well I am no professional pilot, Not a test pilot, My instruments were working fine - except the rotor tach was not calibrated right - but my instruments aren't certified, etc...etc...

And like I said, the numbers I got doing these same tests were so close that the margin of error in doing a test like this could have put one blade over the other even when that is not the case.

What you are saying about the need for more trim makes sence cause the Sportcopters would have needed alot more trim spring to be flown hands off. I didn't fool with my trim spring, I just held the back pressure on the stick and kept the gyro at the airspeeds I had picked for the different tests.

Let me once again describe one of the tests, the time to climb and rate of climb test....

I was already up in the pattern, had been up long enough to make sure the engine was up to temps and I flew downwind for runway 4. I turned base to final and came down as if I were landing. At 100 feet AGL indicated on the altimeter I leveled off and brought the power back in and brought the airspeed to 60 mph indicated steady. I flew at 100 feet and 60 Mph the length of the runway to stablize everything and right at the end of the runway I nailed full throttle and held it there. At the same time as adding full throttle I hit the start button on a hand held stopwatch I had in my left hand.

I climbed at a rock steady 60 mph and straight out off of runay 4 so as not to induce any advantage or disadvantage by measuring in a climbing turn or so on. As I approached 1 minute of climb I was observing the altimeter to see how much higher I was, and at the 1 minute point I was exactly 700 feet AGL with both blades. I kept climbing till I saw exactly 1100 feet AGL on the altimeter and at that time I stopped the stopwatch and my times posted at the beginning of this thread reflect that test.

I do remember figuring the time to climb to 1000 feet was not nearly as good as the first minutes worth of rate of climb - 600 FPM. I think it worked out to like 500 FPM since it took nearly 2 minutes to reach 1000 feet. At anyrate, I do not know if 60 is the best speed to climb at, maybe 50 would have gave better results.... But I would be happy as a pig in dodo if I could see a honest 1000 FPM climb with my dominator. The only dominators I have flown that would climb out like that were Scott Lewis' 912 powered single place and the old Red one I sold last summer that had the 100 HP three banger two stroke on it.

Like I said I am open to suggestions on ways to do a re test that will possibly give more credible results. I should also have both gyros and both blades at ROC too if anyone wants to do the tests there.

And last comment, I could have kept the sportcopter blades on the dominator. Barry who owns the blades for his gyrobee, doesn't know how to fly a gyro and at the rate he is going with his lessons - or lack of lessons - I could probably use the Sportcopters forever. He doesn't mind. But I put my Dragons back on. I like the sporty feel of the Dragons over the heavy feel of the sportcopters. That is more important to me than a few MPH difference in speed or rate of climb etc... I am not looking for the last ounce of performance, I am just out to have fun with my gyro. I will put the sportcopters back on sometime to fool around with them, I did like the way I could float in so slow for a landing with them.

gyromike

07-30-2004, 05:33 AM

Chuck,

Wouldn't different airfoils have different speeds for Max L/D?

If so, wouldn't "time-to-climb" have to be at each rotor's best climb speed?

C. Beaty

07-30-2004, 06:45 AM

Ron:

A draggy airframe tends to cover up rotor differences. A Littlewing has less drag than typical pushers and rotor drag differences are more apparent. With a draggy airframe, rotor drag differences will be more apparent in the lower end of the speed range.

A heavy stick means the rotor follows cyclic input more slowly; -move the stick and if the rotor is slow to follow, you'll feel more pressure. The rotorhead gets too far ahead of the rotor disc.

The amount the rotor lags behind the rotorhead depends on the ratio aerodynamic force to inertial force.

If two different rotors weigh the same, inertia will be about the same (altered slightly by tip weight distribution) and the one with the heavier stick is producing less lift change per degree of rotorhead tilt.

Necessary trim spring pressure depends on the pitching moment characteristic of the rotorblade airfoil.

An airfoil with nosedown pitching moment characteristic, like a venetian blind slat, twists nosedown more on the advancing side of the rotor disc than on the retreating side. This periodic feathering amounts to a built in swashplate that applies nosedown cyclic pitch which reduces flapping angle and causes the rotor thrust line to pass farther to the rear of the rotorhead pitch pivot. Tries to rotate the rotorhead nosedown and requires more trim spring tension.

The suppression of cyclic flapping removes one source of 2/rev shake; -that due to the moment of inertia of a coned see saw rotor about the feathering axis but introduces another; -the periodic aerodynamic force that twists the advancing blade nosedown.

The ideal is to have a rotorblade that is perfectly balanced about its aerodynamic center (nominally 1/4 chord) and one with zero pitching moment coefficient. The farther we get from the ideal, the quirkier a rotor becomes. Like SkyWheels doing uncommanded pitchups on the big iron. Or Cierva C-30s with negative pitching moment blades not having enough rear stick travel to be able to pull out of a high speed dive.

C. Beaty

07-30-2004, 07:12 AM

Mike: Fixed wings, yes; rotors, no. The wings of a FW are going the same speed as the rest of it but rotorblades are moving so fast that small changes don't have much effect on rotorblade airfoil performance.

But there will be a difference of speed for best rate of climb for rotors with different L/D ratios.

Low drag rotors will produce maximum rate of climb at a lower airspeed than high drag rotors. This is because the masking effect of airframe drag is less.

This is pretty apparent from a plot of airframe and rotor drag Vs. airspeed. I had posted a hypothetical plot previously and looked to post it again but I guess it's on a HD that isn't plugged in.

Russell

07-30-2004, 07:57 AM

On my old Green Dominator I did a test. I held it at 60 MPH IAS and then went to full throttle did nothing else. It would climb at 900 fpm And that was before I repitched the prop ( it was climbing out at reline) After the repitch I never did the test again but I can tell you it climbed a lot faster. Maybe Chuck can do the test?? Does you machine have the 3.00 to 1 box on it? or did that get changed with the clutch addition??
My 50 cents Russ :rolleyes:

KenSandyEggo

07-30-2004, 08:05 AM

Well, I guess that the only way to settle this is for Ernie to start making 8.5" by 30' blades for the lead-sleds.

Udi

07-30-2004, 08:10 AM

I was surprised to learn recently that the Sport Copter machines don't have a trim spring. Does that mean they don't have an offset gimbal rotor head? How, than, do they overcome the blades down-pitching moment? Is the blow-back being cancelled out by the blades down-pitching moment? Is this intentional?

Udi

C. Beaty

07-30-2004, 08:24 AM

Ken J., you remind me of the Indian Fakir who, on his night off, gets to sleep on a pile of rocks instead of his usual bed of nails. The contrast makes it seem he's in Paradise.

Almost any well made rotor will seem perfect compared to what appears to be standard lumpy, haphazardly foamed RAF blades. In spite of some evident exceptions.

KenSandyEggo

07-30-2004, 08:39 AM

Why won't Ernie consider making larger blades? That seems to be the upcoming market, especially when there's really only one other consistent game in town. I can never make the contrast if Ernie doesn't offer the same sized rotor. It seems that if they performed better than the competition and were priced lower, he'd make a killing.

C. Beaty

07-30-2004, 09:49 AM

A couple of reasons, KJ. Until recently, RAF had the 2-place blade market locked up

The leftovers, Marchettis, Parsons 2-place with Mazda engines and others represented a minuscule market and a product likely to sully anyone's reputation. Just imagine what the spin would have been like a few years ago had an RAF splatted in while flying someone else's blades.

If the Sparrowhawk is as successful as it looks like it might be, don't imagine they'll bend over and let themselves be raped by a sole source vendor forever.

I would expect the jumpoff point for making your own blades would be solid prospects for 50 units/year.

KenSandyEggo

07-30-2004, 10:20 AM

I bet you're right. And for right now, the SC blades are the best available for the lead-sled I fly.

gyromike

07-30-2004, 01:10 PM

Aussie_Paul

07-30-2004, 01:57 PM

Ken, I was going to say the same sort of thing. The only true test for our lead sleds is to compare the latest SC blades to a set of DW, and then I would like to compare the OZ ones.

That won't happen because 30' DWs I believe would shake you out of the seat even with a slider head.

Naturally I can't explain it but Chuck can, he explained it to me some time ago when we were discussing the inability of the DWs to work successfully on the lead sled 1200 lb machines.

I believe, and probably incorrectly, that the moment arm out at tip of the big DWs, (30'), with the increased AoA, causes the tip not to be able to move the vertical distance required in the time availible.

Musterers, and there are not many if any that will muster with DWs these days, tell me that when you do a really quick turn down wind, so quick that you lose airspeed, that the DWs slow down extremely quickly, and the machine sinks until the airspeed comes up again. If the blade weights and inertia are the same, then the drag from the twisted up tip possibly slows the rotor so much more quickly.

I would appreciate your thoughts Chuck B. I remember you telling me in approx 1999 that the DWs would not work well on my Rafs at that time. The large amount of shake was the reason were discussing this, I believe.

Chuck I think you mentioned something re the narrow chord of DWs at 30' on the 1200lb machines would have the blade loading too high. I guess the job of changing the chord is not simple. Ernie would have to have all the ratios remain the same, so that would mean another spar die(sp). Maybe with so many lead sleads becoming availible now that it would be viable for Ernie to redo the blades for the lead sleds (29' to 32').

Have I made any sense Chuck? :eek:

Aussie Paul. :)

MikeBoyette

07-30-2004, 02:52 PM

Everyone,
Last time I spoke to my dad about the subject he has no desire to build bigger blades for the led sleds. The main reason is the risk. Most light machines,even the not very good ones have a better safety margin for material strength. When you start getting up to 1200lbs you loose alot of that safety margin. He also found when he started building blades most machines of that size were still running single bearing heads. It is one thing if a guy kills himself, but when takes out an innocent passenger Dad doesn't want any part of that. You are right Paul he would have to re-tool to build bigger blades. Like Chuck said is it worth all that effort and money to sell 50 blades a year? :)

C. Beaty

07-30-2004, 03:44 PM

Udi said:

I was surprised to learn recently that the Sport Copter machines don't have a trim spring. Does that mean they don't have an offset gimbal rotor head? How, than, do they overcome the blades down-pitching moment? Is the blow-back being cancelled out by the blades down-pitching moment? Is this intentional?

You raise an interesting point, Udi.

The first blades I ever flew was a set of plywood blades built as close to the Bensen plans as our skills would permit.

With a standard Bensen type rotorhead; 1" offset between the bearing axle and pitch pivot, no trim spring was required at normal cruise speed, 45-50 mph.

When I started using metal blades (Bensen clones), a very stiff trim spring was required at the same cruise speed, not objectionable in flight but a pain in the rear for ground handling.

I knew what was happening but didn't understand exactly why. Never-the-less, I charged ahead and started reducing the offset until at an offset of 5/8" , the trim spring could be eliminated. Shortly afterwards, I began using Hughes rotor blades and to the best of my recollection, the 5/8" offset also gave springless trim.

A friend of mine, a pretty bright fellow in spite of being from Swainsboro Georgia, used to fly my gyro quite a bit. He kept telling me my gyro wasn't stable but I was used to it and didn't really notice.

Pete went back to Swainsboro, studied the matter and came up with the theory of stabilizing feedback from excess offset balanced out by a trim spring. Pete experimented with a number of variations of offset Vs. trim spring coefficient and concluded that Bensen's standard offset combined with a trim spring having a slightly lower rate produced the most stable combination.

It turns out the plywood blades were over reflexed which gave them a nose up pitching coefficient and increased the cyclic flapping angle, the reason no trim spring was required.

This was long before PCs had become household appliances so the calculation of pitching moment was a bit tedious. Abbott and Von Doenhof, "Theory of Wing Sections" gives a fairly simple method; take the slope of the mean line at various stations and multiply by a tabulated coefficient and do a summation of the results. The plywood blades, taking ordinates straight from the Bensen plans, have a nose up pitching moment coefficient of ~0.04 using the Abbott & Von Doenhoff method.

I broached the positive pitching moment coefficient with Dr. Bensen who stated, emphatically, that his plywood blades had a zero moment coefficient. Oh, well.

The airfoil analyses programs that run on PCs make the determination of airfoil characteristics child's play. Enter an airfoil's ordinates and a complete data set is spit out in milliseconds.

As to why Vanek reduced offset enough to eliminate trim springs, you'd have to ask him. The downside is a reduction of stabilizing rotor feedback.

I'm not even sure Bensen was deliberately seeking stabilizing feedback. It could be that was an accidental discovery that resulted from using the same rotorhead dimensions that gave springless flight with plywood blades when he changed over to metal blades.

I think I said my friend Pete was a pretty bright guy. Pete rigged a pop up mine (I think the GI name is "Bouncing Betty") to pop up to crotch height and neuter his wife's lover. Pete served some time in the Georgia State Penitentiary as a result. Swainsboro is a small town and the cops deduced right away that Pete was the most likely suspect, given his talents and vested interest.

scott heger

07-30-2004, 04:06 PM

C.B., Pete seems like a quite a good ol' boy to have around a gyro. Just don't think I want to meet his wife quite yet......

I would ask you this, that I believe most (light aircraft)gyro blades have best rate of climb in the mid-40 MPH range. In your experience, what is the lowest and highest MPH you have seen for best rate of climb on a particular machine?

Scott Heger, Laguna Niguel, Ca N86SH

C. Beaty

07-30-2004, 04:27 PM

The primary problem, Paul, is blade loading. The tip speed of a rotor is ~66 x (square root of blade load).

Cierva and licensees always, at least after some of the earlier, cut-n-try models were behind them, used 35 lb/sq ft. This results in a tip speed of 390 fps.

If you take one of your 1200 lb wrecking balls and try to fly it with 7" x 30' rotors, the blade area is 17.5 sq. ft. and at 1200 lb, the blade loading is 68.6 lb/sq ft. The resulting tip speed is 547 fps. Pushing the blades through the air that fast simply burns up too much power.

To run your wrecking balls at 35 lb/sq ft would require a blade chord of 14" with 30' diameter. Think you have 2/rev shake problems now?

The ultimate solution is a 3-blade rotor. Then all the shake problems go out the window and you can use as much chord as you like.

C. Beaty

07-30-2004, 05:17 PM

45 mph was the number quoted in all the Bensen manuals as best rate of climb speed, Scott.

But a lot of variables enter the picture. I'd speculate that a Gyrobee with 24' DWs would have a best rate of climb substantially lower than that, perhaps 30-35 mph.

A well streamlined gyro with high disc loading might have a best rate of climb at 75 mph.

Ralph

07-30-2004, 07:19 PM

Chuck,

Your speculations about the Gyrobee are dead on - best rates-of-climb vary VERY slightly with different blades but the average is essentially 35 mph.

Ralph

scott heger

07-30-2004, 07:57 PM

Best rate of climb for my sportcopter is with 25X8 blades 47 mph, with the smaller 25x7 blades it was 43 MPH, make sense? Blade speed has decreased 10- 15% with the bigger blades.

Scott Heger, Laguna Niguel, Ca N86SH

Aussie_Paul

07-31-2004, 03:19 AM

That's a good one!!! LOL.

Thanks Chuck, I knew the therory behind the blade loading but I was trying to think a bit further outside the square!!!!! :confused:

Aussie Paul. :)

C. Beaty

07-31-2004, 06:20 AM

Best rate of climb speed, Scott, falls close to that speed at which total power; power consumed by the rotor plus the power required to drag the airframe through the air is least. It may not be precisely at minimum power speed because of variations of propeller efficiency Vs. speed. It always falls at a speed where the difference between power required and power available is greatest.

The power consumed by the rotor has two parts; (1) the power consumed in generating downwash (lift) and (2) the power consumed in dragging the rotorblade airfoil through the air (profile drag power).

The downwash power depends only on disc loading, AUW and airspeed. Lift power decreases rapidly with increasing airspeed while profile power in nearly constant, increasing slowly with increasing airspeed.

With two rotors having identical diameters, lift power is also identical. The one that has best rate of climb at the lower airspeed has less profile drag power.

The results you show ought not to be. Profile drag power should be less with the wide chord blades; -profile drag power varies as the cube of tip speed but varies linearly with chord.

To put that more simply, the reduction of tip speed should more than compensate for the increase of chord.

scott heger

08-04-2004, 10:40 PM

Chuck, your right, I got the two speeds reversed for the different blades.

Scott Heger, Laguna Niguel, Ca N86SH

The Rock

08-05-2004, 01:32 PM

Chuck,

You said, "If you take one of your 1200 lb wrecking balls and try to fly it with 7" x 30' rotors, the blade area is 17.5 sq. ft. and at 1200 lb, the blade loading is 68.6 lb/sq ft. The resulting tip speed is 547 fps. Pushing the blades through the air that fast simply burns up too much power. To run your wrecking balls at 35 lb/sq ft would require a blade chord of 14" with 30' diameter. Think you have 2/rev shake problems now? The ultimate solution is a 3-blade rotor. Then all the shake problems go out the window and you can use as much chord as you like."

I understand the blade loading concept on heavier gyros. What I don't understand is, why do the heavier and more sophisticated gyros like the Hawk 4 and the Carter Copter that have a gross weights of 3500 and 4200 lbs. respectively only use a 2-blade rotor?

C. Beaty

08-05-2004, 03:18 PM

Good question, Cliff Rock. Even Bell Helicopter, the progenitor of see-saw rotors has abandoned them for 4-blade rotors on their newer models.

The advantage of see-saw rotors is reduced storage space and some cost savings. The disadvantage is irreducible rotor shake.

The Bell Cobra gunship had a see-saw rotor of something like 24" chord and, I'm told, rode like a jackhammer in spite of their best efforts with soft mounting, irreversible servo controls and tuned vibration absorbers.

Brad_King

08-16-2004, 02:16 PM

Hi All,

Don't claim to understand the math behind rotor dynamics. I do fly 29' DWs on a 1200 lb wreaking ball. I have been told by many who have ridden in and flown my machine that it is one of the smoothest 2 place gyro they have seen. Other than a 1.5 to 1 glide slope, the machine has great performance. Steve Mcgowan rode with me after I put the 2.5 Soob on. He was amazed at the climb rate. I don't have a VSI so I can't give a accurate climb rate. Cruises at 75 at 4400 rpm. RRPM around 340-360 at cruise depending on density altitude. Carries 450-500 lbs on a 3500 DA summer day. I hope Ernie doesn't recall my blades but I have seem 450 RRPM at 80 IAS with no ill effects.

Brad King
N6372K
Mad Max II LTC

PS Have a cam grind on the soob est. 180-190 hp.

C. Beaty

08-16-2004, 07:26 PM

Interesting, Brad.

From your RRPM, sounds as though you have a set of the 7" chord blades rather than one of the few sets of wide chord blades Ernie made.

At 1200 lb. AUW and 29' x 7" blades, your blade area is 16.92 sq. ft.

Blade loading is 1200/16.92 = 70.94 lb./sq. ft.

The tip speed would be ~ 66 x square root of 70.94 = 556 fps. Some low muzzle velocity pistols aren't much faster than that.

RRPM = (tip speed x 60)/(pi x diameter) = 366 rpm

That's close to the speed of 340-360 you actually measure. The longer blades have a bit more effective pitch than the shorter blades because the twist keeps going which drops the RRPM a hair.

There's nothing wrong with running blades that fast if you have the power to handle it. But it makes the glide a little steep.

Pat McNear flew a set of 7" DWs on his RAF for a while but bitched about rotor shake. I think Pat still bitched about rotor shake after he got his replacement RAF blades.