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Old Jun 14, 2012, 05:17 PM
Never stop being a kid.
BrundleFlyBy's Avatar
United States, CO, Manitou Springs
Joined Jan 2012
543 Posts
Quote:
Originally Posted by seansmiller View Post
As promised, here's some shots and description of my landing gear mount build:
Nicely done. But I have to say right offhand it looks like you went to the opposite extreme, and overbuilt it by a good margin. Any idea how much weight was added?

Seems like a little strategic bungeeing and/or reinforcement of the existing gear wire with the single mount might net most of the improvement in performance and durability with a lot less work and added weight.

No doubt yours looks extremely cool, however. I applaud your ingenuity and workmanship.
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Old Jun 14, 2012, 05:43 PM
Life is simple Eat, Sleep, Fly
Timewarp's Avatar
Germany, RP, Kaiserslautern
Joined Oct 2011
123 Posts
I have to agree, well done job but way way over kill for this light bird.
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Old Jun 14, 2012, 05:46 PM
Registered User
Victoria B.C. Canada
Joined Aug 2007
217 Posts
That is a lot of work and weight. The option would be to learn to be a better pilot and land this great plane the way it should be landed. A light wire between the struts about 1 1/2 inches from fusalage is plenty. Your does look good. What is the AUW at this point?
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Old Jun 14, 2012, 05:49 PM
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Denmark, Capital Region of Denmark, KBH
Joined Apr 2012
4 Posts
Quote:
Originally Posted by BrundleFlyBy View Post
Nicely done. But I have to say right offhand it looks like you went to the opposite extreme, and overbuilt it by a good margin. Any idea how much weight was added?

Seems like a little strategic bungeeing and/or reinforcement of the existing gear wire with the single mount might net most of the improvement in performance and durability with a lot less work and added weight.

No doubt yours looks extremely cool, however. I applaud your ingenuity and workmanship.
Thank you Well I started out doing just that (reinforcing the existing gear wire with the single mount with some bungees) and it was still just as worthless in my opinion as the unmodified stock landing gear. The plastic mounting plate kept braking off the fuselage and the single landing gear wire kept bending out of shape... not to mention the dangerously low ground clearance the single wire landing gear provides. It's just too bouncy for my liking! I don't know how much weight I've added but it's not an issue for me. I've tried it light and it didn't work for me.

I fly my FunCub exclusively in pretty rugged terrain (which was why I bought it) and the entire landing gear costruction simply has to be able to cope with the uneven ground. Which it does now
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Old Jun 14, 2012, 06:12 PM
You down with EPP?
johnnyrocco123's Avatar
Houston, Tx
Joined May 2009
6,850 Posts
Sean Miller,

Do you plan on spending a lot of time on a race track

How much weight did that add?

It looks cool, but I don't see the point
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Old Jun 14, 2012, 07:16 PM
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robs's Avatar
United States, NY, Dutchess
Joined Jun 2002
652 Posts
unsuccessful maiden

I've been following this thread for a while and finally broke down to join the fun. However my first two attempts were disappointing.

I went with the stock motor, aluminum motor mount, 13x4 prop (balanced), 3s 2200 lipos pushed back to vent to achieve the recommended CG 80mm from leading edge. Ailerons and flaps are using HXT 900s, while the rudder and elevator are using HS-81s.

First attempt was with the grub screws as specified in the manual (top 3mm, bottom 1.5mm). Take off run was short and uneventful. However, as soon as I lifted there was a hard torque roll to the right and the right wing touched causing a cartwheel. No damage, just disappointment.

I remembered reading that several have not used the offsets and just gone with the default, I removed the grub screws and tried again. The same thing. As soon as the the plane got light on its wheels it would torqued to the right. Of course I pushed it and tried to lift off while trying to moderately correct with rudder and ailerons ... no luck still rolled to the right

Before and after both attempts I checked and ailerons, flaps, rudder, elevator all looked straight and level. Lateral balance seemed fine. Should I be attempting to add left side thrust via the grubscrews? If so how much? What obvious thing am I missing?
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Old Jun 14, 2012, 07:48 PM
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darknrgy's Avatar
Joined Mar 2012
41 Posts
You have a bunch of posts so I assume you've gone and checked that everything looks nice and straight. I've seen little bends at the tips of a wing cause major trim issues.

Take off straight against the wind. If you are crabbing the wheels might be a little bit out of alignment and some opposite rudder might be the trick you're looking for. If you are crabbing on the runway and then takeoff, the plane tries to straighten out once airborn which can cause a tip stall.

The straightness of the fin and rudder are pretty critical to trimmed out flight on the funcub.

Is it possible you're not taking off with enough speed or pulling up too hard? If your elevator is trimmed too high it will take off prematurely and immediately stall.

By the way, I have my motor on straight and don't notice any issues like you mentioned. iirc motor torque would throw you over left, not right.

Just as a sanity check, make sure your ailerons are not reversed! Seen this one happened to experienced fliers.

Good luck! I haven't been flying for long so maybe someone else has some better ideas.

Edit: hmmm, looking at your head-on photo, everything does look really straight. Nice decorations by the way :].
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Old Jun 14, 2012, 08:30 PM
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robs's Avatar
United States, NY, Dutchess
Joined Jun 2002
652 Posts
Thanks for thoughts. I was taking of straight into a very mild breeze. Wheels might have been slightly crabbed, but roll to the right might was after I got lift. I know it wasn't torqure roll. The roll was just so sudden after lift off, that I didn't know how else to describe it.

I went back and did double check my CG. It was between 75-80mm back from the leading edge, so I don't believe this is a CG issue. It must be something out of alignment that I'm just not seeing. Nor could the other guys at the field. Maybe I'll see something when I go over it again tomorrow with fresh eyes..
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Old Jun 14, 2012, 08:41 PM
RC Airplane (Recently Crashed)
mutha's Avatar
Australia, VIC, Melbourne
Joined Jan 2011
2,979 Posts
Quote:
Originally Posted by robs View Post
Thanks for thoughts. I was taking of straight into a very mild breeze. Wheels might have been slightly crabbed, but roll to the right might was after I got lift. I know it wasn't torqure roll. The roll was just so sudden after lift off, that I didn't know how else to describe it.

I went back and did double check my CG. It was between 75-80mm back from the leading edge, so I don't believe this is a CG issue. It must be something out of alignment that I'm just not seeing. Nor could the other guys at the field. Maybe I'll see something when I go over it again tomorrow with fresh eyes..
>Some kits had one wing slightly thicker than the other - check your axial balance??
>also you might try to dial in some trim for roll prior to takeoff so you can get it in the air and check ...
> also you should not need anything like WOT to take off.

I have a LOT of down thrust 5+ degrees and about 2-4 degrees RH thrust.
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Old Jun 15, 2012, 12:16 AM
Bay Area Prop Buster
Bluhammer's Avatar
Bay Area CA
Joined Jan 2011
3,996 Posts
Mine has never exhibited any kind of torque roll or roll tendencies at all. But, I did have a plane that had terrible constant rolling once airborne, and it drove me crazy. I never did get it figured out as it got destroyed on the 2nd flight. What I suspect was a bad functioning aileron servo and a little tail heaviness or both.
That plane is the only one I've ever owned that just didn't react like a plane should and it freaked me out. Good luck with yours.

Blu
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Old Jun 15, 2012, 02:15 AM
Registered User
United States, CA, Mountain View
Joined Jul 2004
134 Posts
Most folks here have their CG from 60 to 80 mm from the leading edge. It may be worth while moving the CG forward a bit - the FC is fairly forging in terms of CG. Mine is at 65mm at it flies straight and great upside and down.

Quote:
Originally Posted by robs View Post
Thanks for thoughts. I was taking of straight into a very mild breeze. Wheels might have been slightly crabbed, but roll to the right might was after I got lift. I know it wasn't torqure roll. The roll was just so sudden after lift off, that I didn't know how else to describe it.

I went back and did double check my CG. It was between 75-80mm back from the leading edge, so I don't believe this is a CG issue. It must be something out of alignment that I'm just not seeing. Nor could the other guys at the field. Maybe I'll see something when I go over it again tomorrow with fresh eyes..
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Old Jun 15, 2012, 04:17 AM
Agricultural flyer
mixer421's Avatar
United Kingdom, England, Kent
Joined Aug 2007
508 Posts
Quote:
Originally Posted by robs View Post
Thanks for thoughts. I was taking of straight into a very mild breeze. Wheels might have been slightly crabbed, but roll to the right might was after I got lift. I know it wasn't torqure roll. The roll was just so sudden after lift off, that I didn't know how else to describe it.

I went back and did double check my CG. It was between 75-80mm back from the leading edge, so I don't believe this is a CG issue. It must be something out of alignment that I'm just not seeing. Nor could the other guys at the field. Maybe I'll see something when I go over it again tomorrow with fresh eyes..
Could it be a problem with the flaps? Are you using a reversing 'Y' lead or is there flex in one of the control rods? I had to sand quite a lot from the flap hinge line to get one of them to neutralize without the servo chattering.
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Old Jun 15, 2012, 04:43 AM
Aus
ʎןɟ inverted ɹǝpunuʍop
Aus's Avatar
Australia, ACT, Amaroo
Joined Jul 2011
1,267 Posts
Quote:
Originally Posted by mrc3 View Post


... Ended up putting carbon fiber tubing over the linkages to the flaps and Ailerons to stiffen them as they noticeably flexed during servo operation...

Mike
Mike,

The standard linkages shouldn't need re-enforcing if everything is running true and free. You may even risk burning out a servo (or four...). I would recommend checking them. For the flaps (and elevator) your swivel push-rod connector needs to be able to rotate as per step 7 of the building instructions:
'Be careful when fitting the retaining nut: tighten it just to the point where the barrel rotates smoothly, but without lost motion...'
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Old Jun 15, 2012, 04:55 AM
Aus
ʎןɟ inverted ɹǝpunuʍop
Aus's Avatar
Australia, ACT, Amaroo
Joined Jul 2011
1,267 Posts
Quote:
Originally Posted by robs View Post
I've been following this thread for a while and finally broke down to join the fun. However my first two attempts were disappointing.

I went with the stock motor, aluminum motor mount, 13x4 prop (balanced), 3s 2200 lipos pushed back to vent to achieve the recommended CG 80mm from leading edge. Ailerons and flaps are using HXT 900s, while the rudder and elevator are using HS-81s.

First attempt was with the grub screws as specified in the manual (top 3mm, bottom 1.5mm). Take off run was short and uneventful. However, as soon as I lifted there was a hard torque roll to the right and the right wing touched causing a cartwheel. No damage, just disappointment.

I remembered reading that several have not used the offsets and just gone with the default, I removed the grub screws and tried again. The same thing. As soon as the the plane got light on its wheels it would torqued to the right. Of course I pushed it and tried to lift off while trying to moderately correct with rudder and ailerons ... no luck still rolled to the right

Before and after both attempts I checked and ailerons, flaps, rudder, elevator all looked straight and level. Lateral balance seemed fine. Should I be attempting to add left side thrust via the grubscrews? If so how much? What obvious thing am I missing?
Although I haven't tried it, the instruction manual (step 30) refers to hand-launching. Have you tried this? Definitely have someone else check your control surface throws and direction first - just in case. And if you do try this, please do it over some long, soft grass...

I hope you work this out as there is definitely something wrong.
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