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Old May 24, 2011, 09:51 PM
Wonderfully Wicked
The Don's Avatar
Willoughby, Ohio
Joined Jan 2002
13,280 Posts
This plane does not seem to like the excess power. I maidened mine this past weekend on my upgraded power system did one pass at 87 mph (according to doppler app) then went for a full throttle pass and after a second or two at top speed it pitched down then up then down then up then down again and hit the ground and blew itself if to a bunch of pieces. Not sure of the stab fluttered or what but it when from flying to pieces in about 2 seconds.
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Old May 24, 2011, 11:13 PM
Kool Kats Fly RC!! AMA 30462
sonny1's Avatar
United States, CA, Baywood-Los Osos
Joined Feb 2009
2,793 Posts
Quote:
Originally Posted by The Don View Post
This plane does not seem to like the excess power. I maidened mine this past weekend on my upgraded power system did one pass at 87 mph (according to doppler app) then went for a full throttle pass and after a second or two at top speed it pitched down then up then down then up then down again and hit the ground and blew itself if to a bunch of pieces. Not sure of the stab fluttered or what but it when from flying to pieces in about 2 seconds.
Sounds very much like my short-lived maiden flight. At WOT it pitched down and just would not recover, elevator input had absolutely no effect, even after shutting the throttle down. Looks like we have similar looking piles of foam that used to be an F-20. Guess where I got the Hyperflow fan you just balanced for me Don? The fan was undamaged, so installed it in a Phase 3 EF-16 w/ a Don's Wicked 4800kv motor.
On the other hand, the Hobby Lobby 64mm edf's have given me nothing but enjoyable stable flight right out of the box. A Phase 3 Squall HP w/ thrust vectoring will soon join my fleet, (of course with one of Don's motors in it), but not another GP F-20 Tigershark; an inherently unstable design IMHO, definitely not for beginners, or probably even intermediate flyers.

Sonny
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Old May 25, 2011, 03:56 PM
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victapilot's Avatar
United States, SC, Simpsonville
Joined Feb 2009
4,476 Posts
Too late for me!

That's disappointing about Don's crash. I was hoping to see how fast he could get it.

My F-20 was not badly damaged, just broke in half.

I just have to glue the nose back on, and maybe glass it. The plywood inserts popped out, and seem heavy, so I might use glass and carbon instead.

I will definitely make all turns at safe height, probably need low rates for speed. You can see from my video that I banked past 90deg, and that needs to be avoided. I worry that the elevator might be in turbulent air at high speed - thought about elevon and elevator, don't know yet.

My #2 F-20 is still a hanger queen, but I'll probably just fly it stock.

Just saw they are back on sale too!
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Last edited by victapilot; May 28, 2011 at 12:53 PM.
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Old May 31, 2011, 10:56 AM
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victapilot's Avatar
United States, SC, Simpsonville
Joined Feb 2009
4,476 Posts
Flies again!

Here's a quick check flight after repairs. Flew fine no need for trim adjustmet. I did cut back a bit on aileron throws, and added expo - now at 55%

This 2 min flight consumed 550 ma. I did not like the morning sun in my eyes so dumped it down in the pit area.

OK now a rant. That landing stripped another aileron servo. I had another one do the same some time ago. Conclusion is that landing on tough grass is not good, the linkages can still grab. I wish they had put the servo arms out the top of the wing, and I might just do that. Any ideas?

F-20 6S 0511 (2 min 7 sec)
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Old May 31, 2011, 01:17 PM
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anthodenn's Avatar
Virginia Beach, VA
Joined Nov 2006
978 Posts
No wonder you stripped a servo, you came down pretty hard. Did you have enough throw on your elevator? It looks like you needed to flare to a smooth landing man.
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Old May 31, 2011, 02:28 PM
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victapilot's Avatar
United States, SC, Simpsonville
Joined Feb 2009
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Originally Posted by anthodenn View Post
No wonder you stripped a servo, you came down pretty hard. Did you have enough throw on your elevator? It looks like you needed to flare to a smooth landing man.
Yeah, that's true. I'm just saying the control horn linkage is pretty vulnerable, and would be better above the wing. I stripped another servo in this plane when it came off the dolly prematurely and skidded on the grass.

I have replaced the servo and looks like Thursday will be good for another run. I'll go throttle up next time, I don't think I went over 1/2 except for the takeoff.

I would have preferred that the control horns were not pre-installed. Then I would have fixed this by putting them on top. (At least they did this for the elevator). One possible fix is to cut off the ailerons and reinstall on the opposite wing. The removal of the control horn looks hard to do without damage.
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Old Jun 01, 2011, 05:30 AM
Registered User
United States, CO, Lakewood
Joined Mar 2007
3,043 Posts
Try these. http://www.horizonhobby.com/Products...ProdID=PKZ7010
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Old Jun 01, 2011, 06:40 AM
KK6MQJ
Bajora's Avatar
Joined Sep 2004
13,781 Posts
I have a spare vertical stab and, I think, a canopy assembly ... should any of you folks need one!
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Old Jun 01, 2011, 02:46 PM
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victapilot's Avatar
United States, SC, Simpsonville
Joined Feb 2009
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Quote:
Originally Posted by ColoradoHeliNut View Post
Those are a better design, I'll check the LHS.

Thanks!
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Old Jun 07, 2011, 07:46 PM
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victapilot's Avatar
United States, SC, Simpsonville
Joined Feb 2009
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Today's flight

Full throttle at 30sec. Added ply servo protectors, see at end of video.

Lesson learned - don't initiate turn when nose down!!

F-20 6S on dolly (1 min 52 sec)
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Old Jun 11, 2011, 07:59 AM
Fly more Foam
sam51401's Avatar
United States, IN, Sellersburg
Joined Jun 2004
1,016 Posts
I maiden mine over the last weekend after building it at the field during a club event. I also used a Venom 3200mak 4s and it works great!
What have people been using to protect the bottom and leading edges of the stab and wings for abrasion?
Also would like to hear what paint brand and color most closely matches the red for touchup. Other than a few contol hookup changes it has been most stock RxR version. I do have the material to make a rail launcher since the hand launch resulted in a touch ang go with ejected canopy. Even with the canopy off, it really hauled *** and the esc and battery didnt even get warm!!!!
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Old Jun 11, 2011, 08:41 AM
Aka: Tom Jenkins
ApexAero's Avatar
Palm Beach County, Fl.
Joined Aug 2008
4,507 Posts
Clevis's snag way less than easy connectors.............
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Old Jun 11, 2011, 08:58 AM
Fly more Foam
sam51401's Avatar
United States, IN, Sellersburg
Joined Jun 2004
1,016 Posts
That was the linkage change i did. I placed the easy connectors on the servo arms where they have less play. Basically just reveresed the install from the stock. This in turn took out ALL the play in the controls and tighten up the connections. For the speed this plane is going, the tighter the better.
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Old Jun 22, 2011, 04:30 PM
All Electric
Cabertoss's Avatar
St. Louis, MO. USA
Joined Aug 2010
60 Posts
Here's my previous post for matching color red.

http://www.rcgroups.com/forums/showp...2&postcount=99
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Old Aug 11, 2011, 11:18 PM
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sirzeppu's Avatar
United States, UT, Farmington
Joined Aug 2011
1,427 Posts
I maidened my F-20 yesterday, did more flying today and had a couple of elevator servos fail. Was able to get it back on the ground with use of power for elevation on the first one, destroyed it on the second one. First servo failed due to defect (surprising as I was using fairly nice HiTec servos). Second one had it's wire kinked due to my hurried installation. Anyway, I've got bare fuse, wings, tail on the way and will build a new one.

One question:

I messed with the CG a bit...and though moving it back did help with the nose dropping tendency, I was still getting pretty good accelerated stalls at the bottom of loops (even big, smooth loops which seem appropriate for this plane). Anything past 75 degrees of bank would also bring on an accelerated stall fairly quickly. This is my first EDF, so I'm not really familiar with the normal flying characteristics.

When I kept my banks a little less "9G" and didn't try to raise the nose too quickly she flew just fine. Is this normal? Did I go too far on my CG adjustments? The Electrifly Demo video shows the F-20 doing ALOT tighter loops than mine was capable of w/o stalling. It's a bummer my plane got destroyed...I'll have to wait to rebuild and get familiar with it again.
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