Rotor rpm

kheine

Newbie
Joined
Feb 18, 2011
Messages
31
Location
Olathe, Ks
Aircraft
Gyrobee
Total Flight Time
9.9 hours in Modified RAF + 50 hrs. in Gyrobee
I am having a problem so thought I'd ask the knowledgeable people for some help. I have Gyrobee with 447 and 24' DW blades. Am just learning and have done some runway flying only. In Sept., I went to the airport to do some more practicing and my rotor blades will not come up to speed like they had been. I had to get a new "Jesus" bolt and hat bearing guides(?) after losing my other ones. The new hat bearing guides were too long and I had them cut down to the length of one of the old ones that I found. Have been out several times but cannot get the blades to come up to flying speed. Need some help!
Kent
 
Are they teetering freely? How is it that they aren't coming up to speed? Are they flapping? How are you prerotating and what RRPM are you getting from prerotating?
You'll have to give us some more information to be able to help you.
 
Are they teetering freely? How is it that they aren't coming up to speed? Are they flapping? How are you prerotating and what RRPM are you getting from prerotating?
You'll have to give us some more information to be able to help you.

I am using a Wunderlich prerotator. They seem to come up to 120 rrpm with no problem and then I start my roll. After several hundred feet, slowly adding power and stick full back, they barely get to 190 and get the nose wheel up. Adding more power I see top speed of about 220 to 250 rrpm. Is it possible that I don't have enough shims on the teeter bolt? When I set it up, I was just using the hub bar and had it moving freely. Felt like I had just the slightest play back and forth - moving side to side.
Thanks for your help!

Kent
 
I would think that 220 to 250 is where they should be flying if not slower.. Were you at full power?
That machine should have 23' blades anyway. Thats my opion. the 447 stock is very light unless you may have a few added item. Im flying the same rotors as you on my CLT AC with the large Inst. pod, air shocks, air compressor me at 200 and a hirth 65 HP electris start and battery and they are just right for the machine. I dont have a rotor tack installed but they dont fly very fast from what I can tell.
Maybe you have the nose to high. If you are leving out and balancing onthe mains there is no reason it should not come up with full power. Harry
 
Those numbers sound about right Kent. Since you're listed as in in New Mexico I'm assuming you have a pretty high density altitude. If so the 24 footers are probably OK but if you're flying at 4000-9000 foot DA's. Unless you weigh 120 lbs, that little 447 might not have enough balls to fly you very well, if at all. For comparison, Rocky on the Forum has a modified Bee that he uses 25 foot blades on with a MZ202 60 HP engine and a 65" prop. He's a full size guy about 200 pounds or so and he says he gets good performance.

What is your weight, the weight of the gyro, the prop you're using, and the density altitude there?
 
I own Rick Martin's old gyrobee. I have done several hours of balancing on the mains and 5 or 6 runs of flying the runway. I got distracted while taking the rotors off on my last successful run in July and lost my teeter bolt and hat bushings. I was using 23' blades during that time. I ordered 24' blades from Ernie B. and new hat bushings. Since then, things have not felt right. Even using the 23' blades.
The 'bee weighs in at 310 lbs. I am 195. The airport here is 3200' and DA gets to 6000 to 6500 ft. during the hot months.
I assumed my shims were not correct so I started over and things seem to be spaced right. I orginally did not use a rotor tach and did my runs by feel. I had fixed the rotor tach before last few times I flew along the runway just to see where the numbers where.
I realize that the 447 is not a powerhouse but it should work here as several years ago we had several ultralight planes flying around here with 447 and smaller engines.
I did not go to full power on my runs down the runway yesterday but was trying to get the feel back for what had been happening before I lost my teeter bolt and bushings with shims. I slowly increase my power to about 4800 rpm but it seems like it is taking a really long time for the nose to come up and watching the blade rpm it is not increasing as fast as it had done previously. I was using the 24' blades, so maybe I just need to relearn my balancing technique? Do the 24' blades not come up to speed as fast as the 23's?
I will be at Bensen Days this year, so hope to learn alot while I am there!!
Thanks again for any info you can provide.
Kent
Just don't want to mess up now that I am getting close to flying!!
 
Hi Kent - have you had an gyro instruction ?

Is there anybody or any club nearby that can offer you advice and eyeball your machine ?

If there is a degree of uncertainty re the rotors/bolt/bushings then best get some seasoned advice.

Best of luck

Steve
 
Gyros are fairly inefficient so whether a different type UL can fly there or not doesn't mean a whole lot. Longer blades can take longer to spin up but there are many variables. There is a learning curve for how much energy the blades will take and how fast you can spin them up safely. Patience and practice will pay off. As far as the teeter bolt and hats, The blades should freely teeter but not have much side to side play. A couple thousanths side play wouldn't make the blades spin up appreciably slower. If they were too tight and didn't teeter would be a much bigger problem. Too much side play and the blades will bounce back and forth between the teeter towers which will be exaggerated at certain RRPM's. Even then I wouldn't expect it to make them spin up much differently.
My suggestion would be to work on getting the teeter hats, bolt, etc. back to a point where you're confident in them and also have it checked out by a knowledgable person so you can put it behind you and not have the doubts you seem to have about it. Until you regain confidence in it you'll tend to blame it on whatever is going "wrong" or not behaving as expected, and it will be a distraction from the focus you need while learning. If necessary you could bring it to Bensen days for inspection by any number of highly qualified people.
 
A word of caution is that you will have to be wide open to get that airborn and then you BETTER get the nose down and build up some speed or you will come right back down. Especially if you go into a turn and down wind. Also if you come down and flare to hard you may hit the rotors on the ground.
 
It sounds to me from your description that you don't have enough power for the DA.
When you were flying the 23's it was cooler, no?
I weigh two hundred pounds and flew my 503 with 24's at high altitude and DA and could barely make it off the ground at Benson, which is about the same elevation. 447 power in a gyro? High elevation? Hotter air temps? Not gonna be safe even if you get it airborne. Every turn you make will have a large drop in altitude.
I'm a huge proponent of flying the rotors not the power band, and it probably can be done, but its a hell of a way to LEARN how to fly a gyro.....
 
All of the first few flights of my new gyro were done with overly tight teeter bushings (my fault). It had a hard left roll the whole time I flew it. After honing the bushings to the correct tolerance, the left roll was completely gone.

The rotor speed was the same either way.




Gyros are fairly inefficient so whether a different type UL can fly there or not doesn't mean a whole lot. Longer blades can take longer to spin up but there are many variables. There is a learning curve for how much energy the blades will take and how fast you can spin them up safely. Patience and practice will pay off. As far as the teeter bolt and hats, The blades should freely teeter but not have much side to side play. A couple thousanths side play wouldn't make the blades spin up appreciably slower. If they were too tight and didn't teeter would be a much bigger problem. Too much side play and the blades will bounce back and forth between the teeter towers which will be exaggerated at certain RRPM's. Even then I wouldn't expect it to make them spin up much differently.
My suggestion would be to work on getting the teeter hats, bolt, etc. back to a point where you're confident in them and also have it checked out by a knowledgable person so you can put it behind you and not have the doubts you seem to have about it. Until you regain confidence in it you'll tend to blame it on whatever is going "wrong" or not behaving as expected, and it will be a distraction from the focus you need while learning. If necessary you could bring it to Bensen days for inspection by any number of highly qualified people.
 
Kent:

My Bee: 305 lbs.
My Weight w/ helmet etc: 190 lbs.

So with fuel, me, the Blue Bee, we take off at 515 - 530#

Dragon wings 23ft fly FINE for that weight and MSL, and 24 ft will fly fine AND land with more forgiveness, but will take much more runway to spin up.

How about the prop pitch, can you lock up the gyro on the ground (Point the nose into a building and rope the tailwheel to your truck hitch) and get the engine to hit redline?

If not, and if the engine is tuned and the fuel/oil mix is CORRECT, then you may have TOO MUCH Pitch (like tuned for cruise, not power) and need to adjust it back a bit.

How about fuel? IS IT FRESH!!! Mixed at the right ratio? TOO much or TOO little oil can be a power killer, a marginal engine anything you can do to get more oomph is a smart thing to do. Dump the fuel and start over with fresh mix that you know is perfect.

Carbs? Jetting is the same for your seller's airport as for your??? Who knows, maybe one day the jetting was OK, but conditions changed enough that now it isn't right? I dont', too variables to talk about here. But if you are over jetted, then you are losing precious power.

Plugs? When were they changed, what color are they?

In other words, what is the engine doing back there, giving you 100% power or not? Cuz you're going to need ALL of it with that little weed whacker Rotax.

If you dont' have enough room to take off with the 24's, put the 23's back on.

Oh, and when you put your rotor on the head, you should be tightening the teeter bolt to take out ALL the slap and space between the bearings, THERE SHOULD BE ZERO, and I do mean ZERO play between the rotor hub's block and the teeter tower bushings or bearings, what have you.

WHen you say you cut down the bushings to fit, I don't like that one bit. Maybe it's OK for someone else, but I can tell the difference in my stick shake if my rotor is not perfectly centered by as little as 0.0005", and that's a fact jack.

Why arent' you doing a crow hop if you can get the RRPM to 250 with a 24' disk? Seek experienced help, get someone locally who knows what they are doing in the seat to check this out and give you a hand.

I had, at one time, 25' DWs on my Bee for years, and flew them as slow as 220 WHEELS UP, and 280 cruise! I DO NOT RECOMMEND THIS FOR YOU.

The 23's should be wheels up at 260-280, and flying at cruise around 320-340. So if you are at 250RRPM, you are just about ready to crow hop, just floor it and go, man. Once it gets 3 ft off the ground, push the stick forward and build up airspeed, then pull her back and climb at 45 mph max. Then land it for a crow hop.

Too bad you are so far away, we could help you out at Bensen Days April 3-6, NP.

Best wishes,
Gerg
 
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density alttitude is probably the problem,just because airplanes can fly don't make the mistake that your gyro will also fly at that alt.I live in socorro nm, 4,800 ft and i use all 230 turbo charged horse's here in the summer.Gyro's need a lot of HP compared to fixedwings. If you new at this,please go get help,or you may never live long enough to regret it.

best regards,eddie.....
 
Thank you for all your input!! It is being digested and stored for use. I have 10 hours of instruction from Henry Foster in Olney, Tx. Family matters stopped me from getting airborne over ther winter. I think I am just not used to the 24' blades and will work with them some more. I am going to upgrade to at least a 503 soon! It was July 4 last year when I was flying the runway with the 23' blades. It is about 25 degrees cooler now than then. No one else close by to look things over but I am taking things slow and careful.
I have tied the gyro down and am getting 6300 static rpm after changing the jets right after I brought the gyro home from the Houston area. Wish I could bring it to Bensen Day's, but that is a little bit too far to trailer it!!
I am leaning toward just expecting the 24' blades to come up as fast as the 23's did. Will go back to the airport and practice, practice and then do some more.
Thanks again for all the info and advice. Hope to meet alot of you at Bensen Days!!

Kent
 
There are a couple of us traveling from Houston. I can only go FRI, SAT, SUN and back to work for Monday. Feel free to join me if you would like (and help me drive);-)

BTW...unless you already have the 503...consider the 532 or 582. Big difference. You'll never be completely happy with the 503.

Thank you for all your input!! It is being digested and stored for use. I have 10 hours of instruction from Henry Foster in Olney, Tx. Family matters stopped me from getting airborne over ther winter. I think I am just not used to the 24' blades and will work with them some more. I am going to upgrade to at least a 503 soon! It was July 4 last year when I was flying the runway with the 23' blades. It is about 25 degrees cooler now than then. No one else close by to look things over but I am taking things slow and careful.
I have tied the gyro down and am getting 6300 static rpm after changing the jets right after I brought the gyro home from the Houston area. Wish I could bring it to Bensen Day's, but that is a little bit too far to trailer it!!
I am leaning toward just expecting the 24' blades to come up as fast as the 23's did. Will go back to the airport and practice, practice and then do some more.
Thanks again for all the info and advice. Hope to meet alot of you at Bensen Days!!

Kent
 
Thank you for all your input!! It is being digested and stored for use. I have 10 hours of instruction from Henry Foster in Olney, Tx. Family matters stopped me from getting airborne over ther winter. Kent

Kent,

I think it is great to get on the forum and ask lots of others what their thoughts are on your situation, but it sure seems to me that the person you ought to be asking is your CFI. If you really only have about 10 hrs of dual Gyro training you are marginally trained to be doing what you are attempting and should only be doing it under the supervision of your instructor, with his Solo sign off in your log book. With him being a thousand miles away, I realize he can't be there watching you, but there should still be close communication between the two of you and he should be your number one "go to guy" for any issues you are having, that you are the slightest bit concerned about.

From the description of your gyro I don't believe it will meet the official "ultralight" weight requirement, which means you need to be working with a CFI to legally continue on the path you are on. Even if it did meet the legal requirement so you didn't have to have a CFI sign you off, it is foolish to attempt to fly before your instructor feels you are ready to safely do that. So by all means ask others what they think and consider their answers, but the main person you should be going to and listening to is your CFI. If there is a reason you no longer want to work with him, then find another CFI that you can work with. (we have a great CFI here in UT. at Airgyro) But get a Gyro CFI and let him help you get past this obstacle in front of you. You'll never regret getting the right training and support. You may regret trying to do it on your own if you end up rebuilding your machine after you make a mistake.

I wish you the best but I am concerned by the little bit I am hearing of this situation. Please be careful! We want you to be able to join us in the skies over the Western US.
 
There are a couple of us traveling from Houston. I can only go FRI, SAT, SUN and back to work for Monday. Feel free to join me if you would like (and help me drive);-)

BTW...unless you already have the 503...consider the 532 or 582. Big difference. You'll never be completely happy with the 503.

Thanks for the offer but have already made flight plans and car rental. Leaving here on Thursday and returning on Sunday.

I do not have a 503 yet and would be really happy to find a good deal on a 532 or 582. Always have my eyes and ears open!
Kent
 
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