If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
|
#1
|
|||
|
|||
old days
boB. I believe that the 1/rev vertical is due to tracking, and on my ship,
I either stick track for a ground check or use tip lites. Note us experimental guys have a blade tip mounted LED two different colors, and we can use these tip lites in forward flite. One person tracking is possible. I also check the vertical vibration by using an accelerometer mounted down by the passengers pedals. You are right. My initial tracking adjustments are done with the pitch links and if I needed more in forward flight, I would have to put some trim tabs on the blades. So far my blades run good in forward flite, that is to say I don't have a climbing or diving blade. My ship runs smooth in the vertical 1/rev down in the 0.1ips regions all the way to 90mph. Even when I do vertical 2/rev, measuring in the same spot, I don't get any significant readings. However measuring the horizontal 2/rev just below the swash plate, I can get some significant readings when my fuel level gets below 1/2 tank and I can feel it in the seat and controls. It seems that all of the Baby Belles exhibit this phenomena to some extent. Measurements on the Rotorway Exec showed similar readings but for some reason their vibrations don't enter the cockpit. I'm curious as to the sources of 2/rev vibrations. The two mentioned with Don W I know about and not a lot can be done to either of these two sources, but are there more sources? -- Stuart Fields Experimental Helo magazine P. O. Box 1585 Inyokern, CA 93527 (760) 377-4478 (760) 408-9747 general and layout cell (760) 608-1299 technical and advertising cell www.vkss.com www.experimentalhelo.com "boB" wrote in message ... Stuart & Kathryn Fields wrote: I'll try one: What are the sources of 2/rev vibration in a two bladed helo? I know that I don't have any significant 2/rev in hover, but do in forward flite. Stuart, you are definitely more current than I on blade tracking so let me try to remember. A 1 or 2 per rev vibration which is constant throughout the rpm range should require PC link adjustments. I hope I remember, I did a bunch of these, a vibration which increases as RPM is increased should require a trim tab adjustment. A flag is the easiest way to adjust the blade track although if you have a vibrex you can get it fine tuned. Tomorrow I'll go find my -20s for the OH58, UH1 and AH1 and see if my memory is bad. -- boB copter.six P U.S. Army Aviation (retired) Central Texas 5NM West of Gray Army/Killeen Regional (KGRK) |
#2
|
|||
|
|||
Tracking ---------- old days
Stuart & Kathryn Fields wrote:
boB. I believe that the 1/rev vertical is due to tracking, and on my ship, I either stick track for a ground check or use tip lites. Note us experimental guys have a blade tip mounted LED two different colors, and we can use these tip lites in forward flite. One person tracking is possible. I had forgotten tip lights. On the OH-6 we had cat-eyes but all white reflectors with a different slash in each reflector (- | and /). I tried those (2 of them) on an OH58 but didn't have a bright enough light. I had to do the tracking after dusk. I also check the vertical vibration by using an accelerometer mounted down by the passengers pedals. Even when I do vertical 2/rev, measuring in the same spot, I don't get any significant readings. However measuring the horizontal 2/rev just below the swash plate, I can get some significant readings when my fuel level gets below 1/2 tank and I can feel it in the seat and controls. It seems that all of the Baby Belles exhibit this phenomena to some extent. Measurements on the Rotorway Exec showed similar readings but for some reason their vibrations don't enter the cockpit. I'm curious as to the sources of 2/rev vibrations. The two mentioned with Don W I know about and not a lot can be done to either of these two sources, but are there more sources? My experience is limited at best with only the aircraft I flew in the Army. But I'm hoping someday to be back in the air and I'm interested in what comes from this discussion. One of the aircraft I had high on my list was the Mini 500. Thanks to this newsgroup I've lined through that one. -- boB copter.six U.S. Army Aviation (retired) Central Texas 5NM West of Gray Army/Killeen Regional (KGRK) |
#3
|
|||
|
|||
Tracking ---------- old days
boB wrote: Stuart & Kathryn Fields wrote: boB. I believe that the 1/rev vertical is due to tracking, and on my ship, I either stick track for a ground check or use tip lites. Note us experimental guys have a blade tip mounted LED two different colors, and we can use these tip lites in forward flite. One person tracking is possible. I had forgotten tip lights. On the OH-6 we had cat-eyes but all white reflectors with a different slash in each reflector (- | and /). I tried those (2 of them) on an OH58 but didn't have a bright enough light. I had to do the tracking after dusk. I also check the vertical vibration by using an accelerometer mounted down by the passengers pedals. Even when I do vertical 2/rev, measuring in the same spot, I don't get any significant readings. However measuring the horizontal 2/rev just below the swash plate, I can get some significant readings when my fuel level gets below 1/2 tank and I can feel it in the seat and controls. It seems that all of the Baby Belles exhibit this phenomena to some extent. Measurements on the Rotorway Exec showed similar readings but for some reason their vibrations don't enter the cockpit. I'm curious as to the sources of 2/rev vibrations. The two mentioned with Don W I know about and not a lot can be done to either of these two sources, but are there more sources? My experience is limited at best with only the aircraft I flew in the Army. But I'm hoping someday to be back in the air and I'm interested in what comes from this discussion. One of the aircraft I had high on my list was the Mini 500. Thanks to this newsgroup I've lined through that one. Write 'helicycle' instead. |
#4
|
|||
|
|||
Different small helicopters
JohnO wrote:
One of the aircraft I had high on my list was the Mini 500. Thanks to this newsgroup I've lined through that one. Write 'helicycle' instead. There are several videos of the helicycle flying and it looks very good. Does anyone have any experience with the ultra sport helicopters? http://www.ultrasport.rotor.com/ultrasport496.htm or the Mosquito single place ultralight helicopter and the AirScooter? -- boB copter.six |
#5
|
|||
|
|||
Different small helicopters
boB wrote: JohnO wrote: One of the aircraft I had high on my list was the Mini 500. Thanks to this newsgroup I've lined through that one. Write 'helicycle' instead. There are several videos of the helicycle flying and it looks very good. Does anyone have any experience with the ultra sport helicopters? http://www.ultrasport.rotor.com/ultrasport496.htm The floats option is cool. However the 2 stroke vs gas turbine comparison? or the Mosquito single place ultralight helicopter and the AirScooter? -- boB copter.six |
#6
|
|||
|
|||
Different small helicopters
boB: Believe it or not, whilst I was down in Florida for a ride in the
Hummingbird, I stopped by the Mosquito guy down there for some photos. While I was there he decided to fly his little bird so I stuck around to get some shots. He circled the field a few times and buzzed us once and then landed, got out and came over to me and said: " You want to fly it?" I thought he was crazy. Let some yahoo get in a single seat helicopter that weighed less than 300 # and go for a ride? He said take it around, I think you can handle it. I got in the thing and the check out was "Engine 6,000, EGT lesst than 1600 and he backed away. Knowing I was in a very light helicopter and expecting the thing to be at least twitchy, I ran it up, felt with the pedals to get the nose pointed and began to slowly ease the collective up. The thing wanted to go sideways so I set it down and made a small correction to the cyclic and again raised the collective. This time the little bugger came up to 3' and just set there. Stable as a Huey. Less than 15 sec later I was hover taxiing the thing all over the field. Set it down, pick it up not problem. No nose wander, no sideways movement just a very steady hovering little bugger. The blades were not symmetrical so I expected to feel some varying collective pressure as the angle of attack changed. I couldn't feel any change. I was impressed. However, with only 15 minutes of hovering about I decided not to put it in the air. Later discussions with the owner showed that he had never had a lesson in any helicopter. He had about 15 hrs TT at that time and was impressive in his operation of the thing. Then I learned that there were two other guys flying these buggers that had self taught with no prior helicopter experience. Now it seems that some of them have taken some R-22 lessons and found that the R-22 is much harder to handle. I'm a 2 stroke phobic from my motorcycle racing days, but since they went to the ceramic coated pistons, the Mosquito hasn't had any reported piston problems. They are also working on using a twin cyl, turbo charged injected 4 stroke. I wouldn't mind having one with the 4 stroke. BTW the Airscooter has no collective control. Autorotations are not possible. We've been around the Ultrasports a bit but have no hands on experience with them. At a recent event there were two flying quite a bit. They did have to re-jet for the altitude. -- Stuart Fields Experimental Helo magazine P. O. Box 1585 Inyokern, CA 93527 (760) 377-4478 ph (760) 408-9747 publication cell "boB" wrote in message ... JohnO wrote: One of the aircraft I had high on my list was the Mini 500. Thanks to this newsgroup I've lined through that one. Write 'helicycle' instead. There are several videos of the helicycle flying and it looks very good. Does anyone have any experience with the ultra sport helicopters? http://www.ultrasport.rotor.com/ultrasport496.htm or the Mosquito single place ultralight helicopter and the AirScooter? -- boB copter.six |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
UAV's and TFR's along the Mexico boarder | John Doe | Piloting | 145 | March 31st 06 06:58 PM |
So I invested my US$6°°.....GUESS WHAT!!!... less than ten days later, I received money | [email protected] | Owning | 1 | January 16th 05 06:48 AM |
Reno Air Races -- 2600 Miles in 2 Days! | Jay Honeck | Piloting | 88 | September 25th 04 03:48 PM |
Review of Eleven Days of Christmas--was Friendly Fire Notebook | Ed Rasimus | Military Aviation | 1 | April 18th 04 11:15 PM |