AirGar

My Feedback: (7)

The last few planes I've put together, I've been sealing the hinge lines with "Radio Box Tape". This was on the recommendation of my LHS who flies Pylon. So far so good....

Packing tape, Monokote will work too. I even heard someone using first aid tape! I guess anything is better than nothing!

Pull-pull for the ailerons, eh? I'd probably put one in each wing....

You said the "entire fin" was shaking? That could be a serious problem. Wish I could take a look at that for ya. You need to find out what the problem is....like pronto! Can you snap some pics?

Back when Cermark was producing the F-20's, they had problems with the "fin block" not being glued in enuff from the factory. Ask me how I know....the whole thing came out of it, pulling out of a low inverted pass.

When I told Cermark about it, the guy just laughed. [:@]

Gary

Razor-RCU

My Feedback: (50)

It just depends on the person... If you want unlimited performance get the Jett-50, maybe a West-50 then after that the Rossi-45/53 and Webra-50GT would be my next choices...

If flying with a Standard 46 I would try a 10x6APC then a 9x7APC for improved speed, but the take-off roll will suffer on the 9"

cardinal7

THanks Airgar, Razor and freebird!! I think the tape idea will help a lot. Sorry to hear about the fin falling out in midair, but that happens when you buy a plane from guys who are building it for next to nothing pay. Its amazing however that the thing flew out in flight!!!

I will try and put some pics of the tail assembly on here if i can please send the pics to you again razor!?!?!?! Thanks for posting my other ones last time too!!! By the way, how much are those engines you guys listed above??? I want cheap speed, not really into putting an expensive engine on this plane yet until I know I love it and want to do more with it. I got a 10X6 prop laying around somewhere, I will switch it out and see how it goes on this cheap .45. THankS!!!
P.S.- Freebird, get a sportsman so i can find out if its as bad as mine seems to be!!

Razor-RCU

My Feedback: (50)

The Rossi-45 is $140, The Webra about the same, the Jett-50 is $260 and the West-50 is close to $200- (these are rough estimates)

On another post I mentioned finding a few engines used but at a bargain! As I recall---

Rossi-45 : $75- (Like new- with mini-pipe)
Webra-50GT : $75- (like new)
Jett-50 (2) : $175 and $160 respectively (1 awesome the other fried-)
Irvine-53 : $75- (Like new)
YS-45 (no pipe/muff.) : $75-
OS-50SX Like new with tower muffler--- (got it on a Topcap RTF $150- for plane/engine/servos etc.) Sold the plane to my bro. for $100 that makes my SX a $50- engine!
Fox-50 : (Great condition) $50- (Just ran this tonight... no numbers yet but runs awesome!)

Also just bought a TT Pro-46 minus muffler (Good condition) for $35 bucks- with a 9x7APC and Tower Muffler, these are screamers!

These are all outstanding engines that would breathe new life into your prop-jet!

I am generally poor but always looking for a good deal- takes time and work but it is worth it!

AirGar

My Feedback: (7)

James,

You ever try running a higher nitro in your Rossi 45?

What happened to the Jett 50? Have you contacted Dubb to find out how much to repair it?

PS.....I'll give you $51 for your 50 SX....

Gary

AirGar

My Feedback: (7)

Cardinal,

Believe it or not, when the tail section flew out of the plane I throttled back, however it was "out of control", but I did manage to get it to "land" on it's wheels. I tore out the front wheel and one in the wing. I repaired it, but eventually lost it.

I found a silver (Cermark F-20 ARF) on Ebay a couple months back, but the guy ending up selling it locally.

I still have the DC F-20 ARC which I'll probably finish over the winter.


Gary

MustangAce

My Feedback: (3)

I made a mistake earlier. I have the CERMARK F-20. Not the Kangke. The instructions were terrible so I actually used the Kangke instructions that I found online.

I have even ordered a new canopy from Kangke. It is identical to the Cermark. All parts are interchangeable.

I have noticed the CG seems a little far back. 5 3/4 inches from the wing saddle. The manual says between 5 1/2 to 6 1/4 range.

This is the same as the Sportsman Aviation F-20 has in their instruction manual (5 3/4).



MustangAce

Revver Brother #68

freebird1

My tiger shark will have to wait a week before she can take off. The kit had a small fuel tank. The Rossi engines love fuel. I tried to in stall a larger tank (12 OZ) with no luck. I looked at every tank that you can imagine. I have decided to go with a hopper system for the tank (like a Helli). The kit comes with (if I did the math right) close to a 7 OZ tank. I will add an 8 OZ tank behind it. This will give me close to 15 OZ.


MustangeAce, What did you do regarding the small tank. I would think that the Webra was better than the Rossi on fuel, but still the tank is small. What is your flight time?

Thanks, I will keep you posted.

Freebird

MustangAce

My Feedback: (3)

I fly for about 6 min then land. I have never ran it out.

My first 3 flights I did have 2 deadsticks. The small tank doesn't leave much room for foam inside the fuse. The vibration caused many air bubbles therefore deadsticks with a new engine. It runs great now.

Also, I think Flyboy Dave made another hatch and Dremeled room for a larger tank.


Very Important to remove then reglue the rudder base. It comes inside the airplane almost as if it is glued but it is not. If your plane is already together make sure you tug on it hard to make sure it doesn't come loose. Better on the ground than in the air and lose everything. my 2 pennies

freebird1

Hi all

Mustangace, did you have trouble where the belly servos where to go? I am putting them on the side of the fuselage in side of the belly saddle. The pull pull system on the wing was either hitting the belly servos or was way to close for me. I have had to make a few more Mods. This bird will fly this week! I will post the performance and speed. I will also post some photos of the Mods if I can figure out how. Anyone have help with posting photos.

Freebird

MustangAce

My Feedback: (3)

I really just followed the instructions on the servo locations. I made sure they were recessed into the fuse.

Pics- just click on Click here to upload!

Razor-RCU

My Feedback: (50)

I'll post the pics send them to:

[link=http://My E-Mail][email protected][/link]

Flyboy Dave

My Feedback: (21)

I have had rudder flutter on both the .40 and .60 size Cermark F-20's.
They weren't designed as speed planes....just sport fliers. The hinge line
on the rudders is a good example of poor design. The hinge lines need to
be tilted back on a 7 degree angle, like on real planes....to keep them from
fluttering. Once you push them over 100, into the 115-125 range, the ugly
problems raise their heads.

The ailerons are of poor design as well. [] If you have been keeping track....
you would have noticed that the demise of all the big F-20's was due to flutter. [X(]

First I had elevator flutter (on the 60) which resulted in a crash, then I had aileron
flutter because of the too large, poorly positioned ailerons, and flexing torque rods
....then finally rudder flutter due to the poor design, and the soggy torque rod on
the rudder.

Maybe the "F" stands for flutter ?

Still, I love the planes.

MustangAce

My Feedback: (3)

Were all the gaps sealed??

Flyboy Dave

My Feedback: (21)

.... You betcha', Red Ryder....both sides. (clear Monocote)

freebird1

Flyboy Dave, you are not making me feel at ease for my first flight I changed the rods first thing when I saw them. Solid as a rock now with no gaps anywhere. I 'll take her easy for the first time up. On the second flight I will let her go. I do not like the rush of a recovery, but it is the reason why I stop playing golf for the hobby. Man, sure is alot more $$$$$$. I will be on the lookout for the flutter. Thanks for the heads up. Flyboy Dave, would you say the best thing to do is make the rudder fixed and glued straight. Love the plane and wise to have it around for a while. No 3D for me just SPEED.

Freebird

Flyboy Dave

My Feedback: (21)

We have four F-20's at our field....all the rudders are locked. Had they been
designed properly, like a jet tail....and perhaps uses a pull-pull inside the
fuselage....they might have worked out OK at speed. The way they are is
ok in the 75-85 mph range. At anything over the ton, the rudder becomes
a liability. []

Lock-up the rudder, and just keep the nosewheel steering. [sm=thumbup.gif]

FBD.

freebird1

I think I will take your advice and lock the rudder. I will take her up for an easy go for her first flight so I can see her in the air (75 80 MPH). Any suggestion on how to lock the rudder.

Freebird

Flyboy Dave

My Feedback: (21)

I glued the bottom of the rudder to the fuse, disconnected the push rod
from the servo, and fastened it down with a zip-tie and some glue. I could
saw through the glue on the rudder, hook the push rod back up....and have
it back the way it was in about five minutes.

FBD.

Razor-RCU

My Feedback: (50)

Well my rudder is functional (un-necessary) and has not fluttered "yet"- the airplane is not very fast though.... I have the Tower-75 like Dave, had an APC 10x10 turning 14K still looked slow-

I thought about making the rudder/steering servo into JUST a steering servo-



I don't fly it much since I have the Patriot(s) and a Whip-

AirGar

My Feedback: (7)

James,

What's funny, is FBD had flutter from the git-go with his TH 75 powered F-20, while I never experienced any until just recently. My guess is there are some that may have more slop in the linkage than others. I did take evey caution to make sure mine was tight, however, even after I started getting flutter, the linkage still didn't feel too bad.

The point is, if you don't immobilize the the rudder.....keep your eye (and ears) on it. ONE bad flutter can ruin your whole day.

My linkage was eliminated completely, with the rudder being pinned and epoxied.

As FBD mentioned though, if the TE of the rudder is kicked at a 6-8 degree angle, this would be a great way to start if you wanted to keep you rudder functionable, and of course...with slop free linkage.

Plus, it would allow you to still do a high speed knife....which are pretty as can be!

Keeping the air from hitting the TE of the rudder evenly, has got to help, and will be the way I set up my DC F-20.

That one will either have the West 50, or the Jett 50.....NO DOUBT!

Gary

angelrcdesign

My Feedback: (40)

CAN I ASK A QUESTION ............DOES THE F-20 HAVE A SINGLE CONE? AND THE F-5 HAS TWO CONE??

bob27s

My Feedback: (19)

Angel......

Design wise...that is correct. The T-38 Talon and F-5 Tiger series had twin engines. The F-5G/F-20 had a single, larger, engine.

Plan forms were similar, and for some of these sport model designs I have seen, folks tend to use the designs interchangeably.

Personally, I kinda like the slimmed-down, coke-bottle look of the T-38 and early F-5s.

Bob

Cyclic Hardover

My Feedback: (3)

I thought about that once. I am going to recover the wings in the next year or so and I might just recover the whole thing and lock that rudder up.

Also by designm the DC F-20 is really and F-5

angelrcdesign

My Feedback: (40)

Bob.....

How about down sizing my t-38 to a .40 size??