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Vagabond Problems

Old 06-20-2005, 03:19 PM
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papermache
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Default Vagabond Problems

Fellas,

I have a Vagabond which I built from MAN plans from the 1980s by Bill Winter. It's got a 72" span, 3 channel R/C assist and I have an OS .25 LA up front with a 9x6 prop.

When it flies, either from ROG or hand launch, it assumes a "nose up" attitude and sways back and forth like it's on a pendelum. If I back off on the throttle the swaying becomes manageable, but it's still axially unstable. If I cut the power completely, however, it assumes a practically picture perfect glide attitude.

So what am I doing wrong? Do I need a smaller engine, more downthrust, smaller prop, all of the above, none of the above or what? I'd welcome any advice. Thanks.

papermache
Old 06-20-2005, 09:06 PM
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Gollywock
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Default RE: Vagabond Problems

Paper- Some years ago, I built a Paul Plecan 'Simplex' from Model Builder plans with a K&B .20 Sportster engine. At high throttle, it would do the same thing. At idle, it would glide forever. I cured it by going to a 12X6 Master Airscrew 'Antique' prop. The little K&B wouldn't turn over 6,000 RPM with that huge prop, but I could fly all day on just a few clicks above idle.
I hope this might be of some help- Jim
Old 06-21-2005, 08:22 AM
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EASYTIGER
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Default RE: Vagabond Problems

Dutch Roll. Too much dihedral. This is the reason why so many modern versions of the old FF jobs show two different sets of wing joiners, one for RC, one for FF.
Now that the wing is built, it's too late!
Maybe the large prop trick? Never tried that.
Old 06-21-2005, 05:31 PM
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Default RE: Vagabond Problems

Try adding a bit of down thrust, a little at a time. Maybe start with a single washer under the back of the engine mounting lugs at the rear mounting screws. Brodak also sells some plastic offset wedges that do a better job than washers. That description of the 12-6 prop on a 20 comes pretty close to the power level of some of those earlier 60s some of these older planes were built for.
Old 09-01-2005, 01:15 AM
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Grampaw
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Default RE: Vagabond Problems

Years ago I built an Ace All Star Bipe. After Take Off it would go into that Dutch Roll bit, and after a few crashes trying to get it to settle down and fly right, I accidently discovered a cure (for it anyway>0 Oh yes, it was a tough little plane and survived the crashes, which is why and how I finally got to enjoy flying it. After watching and trying to fight if out of a few Dutch Roll situations, I just got disgusted one day and simply let go of the stick, and the danged thing settled down on its own and began a gentle climb to flight altitude! Let a more experienced pilot try it for you, and who knows. GP
Old 09-02-2005, 08:46 AM
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Default RE: Vagabond Problems

I had one of those All Star bipes. Great flying plane. Talked with a lot of flyers who had trouble getting them to fly. They were surprised to find out I was taking off grass with an HB 15. Everybody I talked with who had problems were using engines in the 19 to 29 range. Way too much power. In fact, I had drilled my mounts to fit either the HB or a Fox Schnuerle 15. They were the same width, and the mount only needed 6 holes. After talking with a number of people who tried the plane with the larger engines, I decided to stay with the HB. 12,500 rpm on an 8-4 prop was perfect, the 14200 or better I was getting on the Foxes would probably have been too much power. In the original RCM article, the designer talked about takeoffs from hard surfaces with as little as 09.
As far as Dutch Roll under power with old timers, when they get nose high under power, it's sometimes a matter of the large wing blanking the tail surfaces at high angles of attack and causing partial stalls. I had this problem early on on a 72" Spook 72 with a K&B Stallion turning an 11-5 prop at about 10500 rpm. Added 3 4-40 wahers under the rear of the mouning lugs. Old FFers would usually correct this with engine down thrust, even with the old engines turning big props at what would be fast idles on our newer engines.
Old 09-05-2005, 01:17 AM
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Grampaw
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Default RE: Vagabond Problems

50+, I had a Fox Schneurle 15 on my All Star, and it did move with the Fox. I never tried any other motor on it, so I don't have any data to compare it too, but it was a bit hot on landings, even at Idle. Maybe my Fox .15 Schneurle was too much for it, but back in those days I was pretty green at all this R/C stuff, so what the h__ did I know? Come to think of it, that question may probably still be applicable today. I later scratch-built a larger version, 2X the original size, and with a borrowed .40 Enya on it, it was a sizzler! When I had to return the Enya, I gave the enlarged All Star to a friend who never flew it! He was chicken. It was fast, but controllable, and in the mid RPM ranges it handled flew very well. It really was, and is, a good sport bipe design. I better get off this thread as I have a new Magnum .15 on hand and just may talk myself into building another All Star...when I really want a DH Tiger Moth in that size. GP
Old 09-05-2005, 09:16 AM
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skylane42
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Default RE: Vagabond Problems

I had a All Star Bipe too. I used a Cox Med .09 and had plenty of power.. I flew it with rudder and elevator. I did switch it to a .19 later on and it was just a little rocket.. I thought it was just too fast with the .19. I sold it after a couple of years and the guy flew the plane until the wings became U shaped. That little plane was in the air for over 5 years. I still have a kit in the basement. One other thing not mentioned is to check the CG and maybe even try to shift it abit.

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