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FT Racer Narrow Fuse/Speed wing

Sero

Well-known member
#35
Maiden success! Just ran one pack with the 7x6 Master Airscrew Scimitar prop. This prop only pulled 60 amps during the static test, obviously more potential for speed. I took it easy just to get the feel of the plane, flaps worked well, needed zero trim and was very predictable.
At moderate speeds there was a tail wobble happening. I remember that with my previous stock racer I had but at the time I felt it was the soft vertical stab causing it, I re-enforced it and it reduced the wobble but didn't eliminate it. The vertical stab on this plane is rigid so I'm wondering if I have a bit of Dutch roll happening.

Here is a video from a friend (I had a large audience, for some reason I wasn't nervous...??), its not very clear, will use a different camera next time.

Video
 

Arcfyre

Well-known member
#36
Are you using an RX with a built in stabilizer? If so your rudder gains may be set too high, causing your "booty shake" issue. I had the same problem on mine.
 

Sero

Well-known member
#37
Are you using an RX with a built in stabilizer? If so your rudder gains may be set too high, causing your "booty shake" issue. I had the same problem on mine.
Nope, no stabilization. Maybe that's an option to eliminate this.
First I need to verify if it is Dutch roll or something else.
 

Chuppster

Well-known member
#38
Nope, no stabilization. Maybe that's an option to eliminate this.
First I need to verify if it is Dutch roll or something else.
If it's fluttering without stabilization, I would recommend strengthening things so that they don't flutter.
 

Sero

Well-known member
#39
If it's fluttering without stabilization, I would recommend strengthening things so that they don't flutter.
Pretty sure its not flutter. I didn't see it at higher speeds, the whole plane was moving in what looked like small amount of yaw and roll and it was a very low rate, about 2-3 oscillations per second. I believe flutter usually gets worse with high speed, usually can be seen coming from a tail surface or wing and the oscillations are fairly quick.

The vertical stab is feathered and has 2 pieces of carbon fiber in it and the horizontal stab is also feathers and has one cf rod, the tail is fairly rigid.

Next flight I'll take a closer look and hopefully get a better video.
 

jfaleo1

Junior Member
#40
Pretty sure its not flutter. I didn't see it at higher speeds, the whole plane was moving in what looked like small amount of yaw and roll and it was a very low rate, about 2-3 oscillations per second. I believe flutter usually gets worse with high speed, usually can be seen coming from a tail surface or wing and the oscillations are fairly quick.

The vertical stab is feathered and has 2 pieces of carbon fiber in it and the horizontal stab is also feathers and has one cf rod, the tail is fairly rigid.

Next flight I'll take a closer look and hopefully get a better video.
No this does not sound like flutter, but it does sound like dutch roll. I have had bad luck with the tip plates you are using personally. They are not going to help the dutch roll since they are not aft of the center of lift. Purely drooped tips have helped my previous efforts but I think your fix might be a dorsal fin (see cessna 172 vertical stab) or a ventral fin or fins (see Citation XLS or Citation Latitude) these may help the stability and control.

All of these installations were to reduce dutch roll or yaw issues. The dorsal fin is the easy one the ventrals need to be angled so as to not cause pitch issues.

Once agin just thoughts on things to try.

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