RAF Blade Balancing!

[Rick Whittridge]

After many different attempts to get my RAF blades smooth with adjustments, I took them back off my Twinstarr for a static balance test. Just as I thought they where out of balance. It took 24 AN fender washers to bring these blades into balance. The washers where put on the blade strap bolts until I could get them into balance. I don`t know much about the blades eccept they where delivered to Don Farrington at Mentone some years back. Blade #`S are 3011 T.C. & 3037 T.C. It seems to me that the blade #`S should be brother & sister not so far apart? Anyway so much for quality control. I have not had a chance to try these after the balancing because I still can`t figure why my rotortach isn`t working.:rant:

[Harry_S.]

Rick...I've asked before but had no response, unless I missed it. I know you have RAF blades, but, do you have an RAF rotorhead?

Another question...if you have the RAF head, do you have the RAF tracking tools? If the answer iis yes and no...then, at best, it's a hit or miss to make a reasonable adjustment.

A few years back, I had, I think 7 or 8 washers on the end of one blade to static balance the blades. In subsequent flights, I found that I had removed all but one washer to achieve a relatively smooth rotor. So, that meant that static balance doesn't necesarilly contribute to a smooth rotor.

Have you checked for electrical continuity in your rotor tach circuit? I've had two disruptions in mine, in the past.


Cheers :)

[Aussie_Paul]

After many different attempts to get my RAF blades smooth with adjustments, I took them back off my Twinstarr for a static balance test. Just as I thought they where out of balance. It took 24 AN fender washers to bring these blades into balance. The washers where put on the blade strap bolts until I could get them into balance. I don`t know much about the blades eccept they where delivered to Don Farrington at Mentone some years back. Blade #`S are 3011 T.C. & 3037 T.C. It seems to me that the blade #`S should be brother & sister not so far apart? Anyway so much for quality control. I have not had a chance to try these after the balancing because I still can`t figure why my rotortach isn`t working.:rant:

Rick do your blades have the threaded AN4 screw in the end of each rotor at the approx 1/4 chord point. The later blades have this so that you can adjust the spanwise balance at the tip with smaller washers.

Aussie Paul. :)

[paulp]

Howdy Rick,

I don't know about the older RAF blades but the new MK 24 series blades that I have on my machine fly super nice. It took a little bit of tweeking but I have zero stick shake an minimal cabin vibration.:usa2:

[Timchick]

Also call RAF and make sure your blades are not the old one's that have been recalled out of service. Bo Collins up in Macon had some RAF blades when I was up there taking lessons. They shook so bad he had to hold onto his pod winshield to keep it from shaking so bad. He tried everything he could think of to track and balance the blades only to find out from RAF that his blades were old and had been recalled years ago. They gave him a discount on a new set and from what I heard the new ones fly great.

[Rick Whittridge]

I called RAF with my #`s & was told they were brought to mentone for Don Farrington. They didn`t say anything about being defective or a replacement at that time.
Paul, My blades have a 1/4 20 thread in the end of the blades.
Harry, I have a Twinstarr rotorhead & no I don`t have any tracking bars.
I have tracked a few different blades in my time & have found that if adjustments don`t work then it is something to do with balance.
I do know that at the root end of the hubbar it has 5 deg of pitch with the scribe marks lined up!

[asmuzsr]

Rick
Have you checked the center of mass of each blade. Each blade must balance, by itself, in the same spot. Just a thought.

[Aussie_Paul]

I called RAF with my #`s & was told they were brought to mentone for Don Farrington. They didn`t say anything about being defective or a replacement at that time.
Paul, My blades have a 1/4 20 thread in the end of the blades.
Harry, I have a Twinstarr rotorhead & no I don`t have any tracking bars.
I have tracked a few different blades in my time & have found that if adjustments don`t work then it is something to do with balance.
I do know that at the root end of the hubbar it has 5 deg of pitch with the scribe marks lined up!


Ok Rick, they are not the real old ones and not the latest ones. I used several sets of these and flew many more sets for customers. They could never be got as good as the latest blades that are made out of house for RAF but the were acceptable. All the new blades made out of house for RAF I have flown are pretty good.

I think there is a 500 hour limit on the hub bar and possibly those model blades as well.

Aussie Paul. :)

[Rick Whittridge]

Has anybody ever had there own RAF blades so far out of balance like mine are?
Is the 5 deg pitch at the root end of the blade correct?

[dragonflyerthom]

Rick

According to my book there is a built in twist in each blade of 3 1/2 degrees at the root, O degrees at the tip. So when the tip of the blade is set to 1 1/2 degrees then the root of the blade will be at 5 degrees pitch. This setting is for up to 3000 ft altitude. The pitch might have to be increase to about 1 3/4 tip for higher altitudes.

Not knowing what type of RAF Blade you have would help. Do you know the generation and type??
I would say you will have to change the Hub bar to have the 5 degrees at the hub and to have the 1 1/2 at the tip.


Thom

[Harry_S.]

Has anybody ever had there own RAF blades so far out of balance like mine are?
Is the 5 deg pitch at the root end of the blade correct?



Rick...not meaning to offend you in any way...but, we need to back off here a bit. Forget about the static balance for now, okay?! I realize you are an experienced gyro pilot but we are playing with rotors that I believe, you have no prior experience with. Correct me if I'm wrong in that assumption.

I have flown with three different sets of RAF blades and all three had different flying qualities that required different adjustments?!

I've found that the scribe marks on the hubbar don't mean diddly. I suppose the marks are a reference to/for the degree of twist...I don't know?!

In all three sets of blades, I have had to de-pitch the blades to get close to a smoother rotor, consequently the scribe marks didn't exactly line up.

With the RAF blades, it is next to impossible to adjust 'em without the aid of the tracking bars. (Maybe buy Stan's bars.)

May I suggest...you remove all the extraneous hardware you put on the blades and start from scratch. You WILL need a set of tracking/pitch tools to make adjustments.

Get to that point Rick and I think we can give you some help from there. You will probably still need some help on the chordwise adjustments.


Cheers :)


PS. I don't know of anyone better at adjusting RAF rotorblades than Dofin Fritts. He has the majic touch.

[Aussie_Paul]

Duane Hunn taught me to have the control lock on the Raf and stand behind the machine and use the WD protractor to measure the pitch angle of one blade to the other. You place the protractor on a repeatable position on one blade and set the bubble in the center. Strand still and not move while you get someone to walk the other blade around to you. Place the protractor on the same spot on this blade and compare.

To begin, have these measurements equal, and the hub bar centered between the towers. Go fly and see what you have.

Next is to use the tracking bars to change the pitch on one blade approx 20 thou on the tracking bar dial gauge, and fly again. If better go another 20 thou. If worse go back 40 thou and fly again. When you get to a point that improvement is not happening shift the hub bar sideways with the adjusting screw by turning the adjustment screw no more than 60 degrees at a time.

As Harry said, sometimes by shifting rotor speed by 20 rrpm for the same load can help.

Aussie Paul. :)

[Rick Whittridge]

Harry, You are not offending me by your past experiences with the RAF blades. I just want you to know that ALL the blades that I have encountered with my different machines needed to be balanced before trying to track them. When I balance my blades I first find the center of the hub bar block. I then drill a very small hole in the center of that block. I then put a pointed center out off my lathe into a fixture type table to hold it. I then turn the blades upside down onto this point in a draft free hangar for them to settle into there state of balance. Most blades don`t require much added weight to bring them into a balance. I use a machinist level to ck them with a very high degree of accuracy. These RAF blades that I have where heavy on one end & had these washers added to bring them into balance. The good thing about doing the blades this way is you can correct them in span & chord before you put them on the machine. This takes all the guessing out of `Oh yeah those blades are smooth' that is always stated from the former owner you have purchased the machine from`NOT' !

[Harry_S.]

OK Rick...I just went back and re-read your post #9.

I have jumped way ahead of you here...sorry 'bout that.

Have you flown these blades in their now balanced condition? How was the track? Personally, I would not fly them...I would fast taxi and get 'em well over 200 rpm and let 'em spool down and eyeball the track from the ground.

If the track was still way out, as was before, they have to be put in track. With the RAF blades, they have to be adjusted with the two bolts at the winglets. Beg, borrow or build a set of tracking tools to accomplish this, Rick. Otherwise, it's really, really a hit or miss situation.

Have you solved your rotor tach problem?!


Cheers :)

[Rick Whittridge]

I got my rotortach working today so now the blades go back on from some more testing!:D

[Brent Drake]

Rick, you should have scratch marks where they are suppose to be set at. And 1/4 of a turn difference makes a very big difference in balance and RPM

[Rick Whittridge]

Brent, I have the blades set at the marks & this represents 5 deg at the root end of the hubbar. It has been windy & cold so I have not been able to fly .

[Harry_S.]

Rick...to maybe give you an indication to how sensitive these RAF blades can be...

I'm still trying to really smooth out the rotor. Last week I tried...I added one washer to the black blade which was needed to center the bubble, statically.

When I flew, the bump was worse. So, I removed the washer from the black blade and added it to the white blade.

I didn't fly until today. A cold front was coming thru this morning and it was cool and windy. I did fly and the bump was less...wind or no...so, after landing and back at the hangar; what I did was to add another washer to the tip of the white blade.

I wanted to fly it right then, but, I had to get home.

I'll let you know what the result was after the next fly.

The tweaking goes on.:drum:


Cheers :)

[Rick Whittridge]

I got a chance to fly my Twinstarr last night after I did my static balancing on my RAF blades last week. I pleased to report that the blades are 80 % better than before the balance.I now need to do some more tweeking .

[Brent Drake]

Very good news Rick. I'm glad you got it. Baldes balancing is a real pain in the a**

[Harry_S.]

Way ta go Rick. Things seem a little better now, right?!


Cheers :)

[automan1223]

I got a chance to fly my Twinstarr last night after I did my static balancing on my RAF blades last week. I pleased to report that the blades are 80 % better than before the balance.I now need to do some more tweeking .



Rick, My 30' raf rotor has gotten rough over time. I got a new setup using lasers aand the tracking is much better I was also able to "string" the blades using the same wizzadry, but I over shot the pitch and now my rotor is too slow, I have also recentered the hub bar in the head but did not get to fly it yet. I am curious where you added weight cause I know I am going to have to do the 3x 's a charm thing. Maxie showed me how to balance blades using a water level but I am curious where you ended up adding weight, on the end or in the middle of the rotor blade. ??

Jonathan

[Rick Whittridge]

Jonathan, I added medium size AN fender washers with a 1/4 hole that I drilled out to a 3/8 hole. I added the washers to the bolts on the blade straps. This did require longer bolts to handle the extra washers. I have done all my blades this way over the years. It seems that the glass blades are the worst to get dialed in. Most alum blades don`t need much in the way of washers to balance them because they are more uniform when made.

[Rick Whittridge]

I forgot to post that my blades are turning 293 RPM solo.

[automan1223]

Rick,

RAF papers say they want 345 rpm for my 30' rotor.

My rpm is 295 with 5 out of 20 gallons and rear seat empty since I reset the pitch. The tracking is great but in the cold air now its way to low, I was shooting for 325, that way loaded would be 355 or so at least that was the rough calc in my head.

I was just curious if balancing along 3 points would be better, some at the root, some mid span, and then at the end, would be a better "average" and lumping a static amount all at one point. Just my thoughts.

Jonathan

[paulp]

Hey Jonathan,

I sounds like from your last post that the "BALANCE" is about right. I beleive that to increase your RRPM you would want to remove an equal amount of pitch from each blade. This should speed up your rotor and still keep everything in track. Use the pitch adjustment bars and try removing about .005 from each blade. Fly it and see what it does. This procedure can get to be a pain. It took me all day and 12 adjustments to get mine dialed in but my blades are smooth as silk so, I consider it time well spent.:usa2:

[Brent Drake]

Rick, If I get my blades to your RPM solo, then with 2 people, the ride doesn't feel right. I had to take some pitch out to bring the blades up to 315 fo a smooth flight with 2 people.

[dragonflyerthom]

Rick

I don't know what your weight on your gyro is but the 310s will give you the best ride. The 295 is just a bit low.

But what do I know

[Caribean_gyro]

I started in 295 to 300 and the vibration was reduce dramatically. But I was liftting in 300 feet and with passenger Heavy guys in 600 feet. Now crusing was 55. I reduce pitch I am crusing in 70 but there is a littelmore vibartion.

The cure is another blade but in the mean time ($$$) I wil just use what I have

Chuck:yo:

[automan1223]

Comparing the undersling of the Sport Copter 30' Rotors to the Raf 30' rotors, I feel there is considerable more undersling with the Sport Rotors, which are a much stiffer blade.....when compared to the glass Raf setup. I am curious if any of you with the RAF blades have increased the undersling and if so had any improvement in the ride ?

Jonathan

[Harry_S.]

Since we're all talking about our 30 ft. rotors and our rrpm, I'd like to make some comparisons, if you will. Solo flight.

What we need to know is:

1) Your weight.

2) Your machines weight, with 5 gals. of fuel.

3) Your cruise rrpm at 65 mph and 10 gals. of fuel on board.


My figures are:

1) 225

2) 848

3) 320-325

Thank you


Cheers:)

[Caribean_gyro]

empty is 780
5 gal= 30
me 220
total 1030
rrpm 290 to 300
60 to 65 mph

STill lowering the pitch. I fynally made my own jig for the dial indicator.

just a note from the factory scribe I have move down around 110 thousands of an inch. and I am not there yet. today I am going to fill it up and see with more weight on the back

chuckP:rapture: