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TopRCModel FW-190

Old 10-15-2020, 06:18 AM
  #1076  
elmshoot
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Steve,
You can see how I did my nose weight. I haven't run the numbers in the current configuration But I'm at least 1/2" back from the recommended position. for your initial testing the factory spec is a good place to start. Just be prepared to remove weight as you get a bit of time on the plane. Gear up or down doesn't seem very critical but if you do it gear down then you can be certain of the CG during the takeoff and land phase. I suspect that when it's all sorted out I'll be 3/4" to 1" back from that point. The elevator does become more effective as the CG moves aft so elevator throw can be reduced. I use Expo to soften inputs around center stick.
I am using all the Aileron throw and with expo dring high speed flight I just leave it a hi rate. Maybe for some scale maneuvers I might try lower throws to avoid overcontrol.
I run triple rates which is common on most higher end radios. Another FW operator commented that he too doesn't need much elevator throw to fly and land either.
Ill try and get throws for you in a few days.
Sparky
Old 10-15-2020, 07:51 AM
  #1077  
affas
 
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What CG are at then? (measured in mm?)

Thanks Alf
Old 10-15-2020, 06:09 PM
  #1078  
elmshoot
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I checked the elevator throws
Hi rate 13 Degrees 18MM. 30% Expo
Low rate 9 12. 15%
These are for up and the down is similar.
I could do all the flying on low rate except for landing, if I bounce the landing I don't have enough throw to correct the bounces.
When looking at the neutral elevator position it is basically flat across the bottom of the stab so I am carrying a bit of down elevator for level flight. My stab is removable if it were going to permanently mount the stab I would move the forward stab tub a little higher probably around 3/32" to correct for the incidence issue. This is also the same on another FW-190 I examined.
In storage the wings are off so I didn't get a measure on the ailerons. Basically about as much up as I can get and about 3/4 of that throw for down aileron. To compensate for adverse yaw.
Sparky




Old 10-16-2020, 05:56 PM
  #1079  
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Default Rudder Cables

God Day
I am at the point of installing the rudder cables, and in my quest to reduce the work required to mark and drill holes I searched several forums to determine what everyone else was doing. For the most part many have used Top RC's recommended placement. I layed out tape lines on the fuselage as a guide. The vertical black mark is the internal former where the retract mounts, and the small black mark is the recommended spot where many have used. I was almost convinced to use that mark until I looked at Sparky's, His cable exits appear to be further ahead by approximately 30 mm from the photo I saw.
My rudder servo arm is 47 mm wide and the rudder horns are 47 mm wide as well.
What are your thoughts on placement?







Old 10-17-2020, 03:20 PM
  #1080  
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What kind of servo torques are you using on the elevator halves. Standards or Minis? Brand, torque, and voltage please.

thanks,

jim
Old 10-17-2020, 03:25 PM
  #1081  
elmshoot
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I matched the servo arm width to the Width of the Rudder horn. If you understand the Ackerman effect that isn't terribly important I could have gone with a shorter on the Servo arm. As I think I posted a picture I attached the tailwheel hook ups using a ball link on top of the arm. So far its been satisfactory. My tailwheel has too much throw and it I usually overcontrol on pavement although it hasn't been an issue on grass. I need to do some more fiddling with the main gear toe as it has lots of drag when pushing and pulling and i think this may contribute to the overcontrol. Ill work on that in the spring. I still need to fly a few more times this fall to burn up all my mixed gas.
As i recall I did the cuts for the rudder where I computed the would penetrate the side of the fuse, and i think I too noted that it was different from the instructions. This might be attributed to using a longer servo arm or they crossed the wires on run to the tail.
Sparky
Old 10-17-2020, 04:36 PM
  #1082  
mgosson
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I've been using KingMax servos for the past few years with great results.
I used one standard size servo for every surface except throttle and tail retract, I chose minis for those. For the elvators, rudder, ailerons and flaps i chose the Kingmax BLS7731CHV. It's a standard size and fit the mounting brackets perfectly. The are a wide voltage servo with 360 oz. of torque at 7.4 volts. The price is around $74.00 each. I purchase them from Gator RC https://gator-rc.com/kingmax-standar...-hv-bls7731chv


Originally Posted by jimkron View Post
What kind of servo torques are you using on the elevator halves. Standards or Minis? Brand, torque, and voltage please.

thanks,

jim
Old 10-17-2020, 04:41 PM
  #1083  
mgosson
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Thanks Sparky,
My plan is to finish the cabling tomorrow.
Old 10-18-2020, 01:49 PM
  #1084  
mgosson
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Default Retract Tailwheel Cables

The saga continues with Top RC's electric retracts.
With the retract servo relocated most everything appears to function properly with the exception of the cables. Once the cables are routed through the supplied guide tubes and connected to the rudder servo the problem begins. With the retract extended out fully the cables have slight tension and allow for tailwheel steering to work correctly. The problem is when the servo begins the draw the retract into its up position the cables get tight, very tight and will allow the retract to pull up only but half way.

I removed the servo arm to see how much movement there is when you activate the retract. With the arm of off you can see the cables draw about 1/4" - 3/8" more than what's available to give.

Has anyone encountered this issue or come up with a fix?



Old 10-18-2020, 06:04 PM
  #1085  
elmshoot
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Yes it is describe in my post 20 pages ago. Tim Evans uses another method as well.

Sparky
Old 10-18-2020, 09:49 PM
  #1086  
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Hi Sparky
That is really valuable information. thank you very much.
Stephen
Old 10-18-2020, 09:52 PM
  #1087  
Stephen Crisp
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Excellent - thank you Sparky
Old 10-18-2020, 09:59 PM
  #1088  
Stephen Crisp
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Hi mgosson
If you are using the pre-installed carbon fibre guides in the tail section, you need to use those as your front reference, and not the servo horn. In this case the width of the servo horn is of no relevance. Stephen
Old 10-18-2020, 10:54 PM
  #1089  
Stephen Crisp
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Hi Mgosson
unfortunately you have to re-route the cables to give you enough slack in the retracted position. I will include a to show you how I managed this.
Stephen

Made 2 sets of pivot points to allow enough slock once retracted
Old 10-21-2020, 03:01 PM
  #1090  
mgosson
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Stephen,
I understand your design and will my best replicate something close.
The cable guide you used appears to be a piece of aluminum tubing affixed to a wood frame.
Once the gear is fully extended I assume the cables has some tension and when fully retracted during the transition no additional force is exerted to the rudder servo.

Thank you for posting the photo.
M Gosson
Old 10-22-2020, 07:29 PM
  #1091  
Stephen Crisp
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Originally Posted by mgosson View Post
Stephen,
I understand your design and will my best replicate something close.
The cable guide you used appears to be a piece of aluminum tubing affixed to a wood frame.
Once the gear is fully extended I assume the cables has some tension and when fully retracted during the transition no additional force is exerted to the rudder servo.

Thank you for posting the photo.
M Gosson
Hi Mgosson
You are correct - the cable guide on the fuselage was raised to the same level as the connection to the tail-wheel, when in the retracted position (to give the shortest distance to be able to give enough slack in the retracted position). The guide on the tail-wheel is mounted far away enough from the tail-wheel pivot to allow for enough movement to allow the tailwheel to turn fully.
The guides are made of servo pushrods (quite hard steel) - I recommend not to use aluminium, as it will be too soft, and the cables will cut into them over time.
Hope this helps. Stephen
Old Today, 12:45 AM
  #1092  
affas
 
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Originally Posted by elmshoot View Post
Just curious how do you know that?
What temps are you seeing reported?

Also factory CG is too far forward. I have now reduced my nose weight by ONE POUND. I am using the three scales method with the wing set at 1 degree positive as that's likely what the wing is at during level high speed flight. About the only thing I've noticed is the required elevator throw is less to maneuver. With expo this might be an airplane that can be flow on one or two rates. Once I get a few more development flights I'll publish my results. I'm only using one rate on my ailerons already.
Sparky
Did you find out where your sweetspot CG is?
Old Today, 05:21 AM
  #1093  
elmshoot
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Read the thread last 20 posts or so, it will answer your question.
Sparky

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