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CMP BF109F BUILDING THREAD

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CMP BF109F BUILDING THREAD

Old 06-06-2013, 06:18 PM
  #2001  
Sharpeye22
 
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Default RE: CMP BF109F BUILDING THREAD

Thanks
Old 06-06-2013, 08:34 PM
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Default RE: CMP BF109F BUILDING THREAD

Mine's at 115mm, flies great no bad tendencies whatsoever.

You don't want the CG too far forward or too close to the wheel centerline, it will tend to nose over
Old 06-07-2013, 05:31 AM
  #2003  
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Default RE: CMP BF109F BUILDING THREAD

110mm may work fine for an electric version, but it's too far forward for a nitro plane due to the fuel loadon take-off. You'll have nose-over problems. I'd say start at 115mm. I believe I'm at 117mm, and it flies great.
Old 06-07-2013, 09:45 AM
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Default RE: CMP BF109F BUILDING THREAD

It sounds like the range on the plans is correct then. The plans say 110 to 120mm. Thanks for the answers all. I split the difference and put it at 115 dry with fuel in it, it is at 108mm. Mine is evaluation 26 gas powered. With how I mounted the landing gear the center of the axels are at 30mm when extended. Taxie test today. I hope I do not have to much of a nose over problem. If so this will not be the first one I have had to deal with that problem. My spitfire is the worst when full of fuel.
Old 06-10-2013, 03:56 PM
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Default RE: CMP BF109F BUILDING THREAD


ORIGINAL: Hot Rod Todd

110mm may work fine for an electric version, but it's too far forward for a nitro plane due to the fuel loadon take-off. You'll have nose-over problems. I'd say start at 115mm. I believe I'm at 117mm, and it flies great.
Ummm...no. The fuel tank is not far enough in front of the CG to effect it much. 115mm will be quite sensitive on the elevators. This plane has been flown quite nicely at 108mm with a nitro two stroke. Nose overs are not an issue. Proper use of the elevator in holding the tail is of course part of the process of most warbirds.
Old 06-23-2013, 07:40 PM
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Default RE: CMP BF109F BUILDING THREAD

As the BF109F taxied onto the runway (taxi way actually) for its 1st flight I seem relaxed but we all know this is far from the case. She throttled up and tracked true with very little rudder input. The tail raised and in just a few more feet she became light on the main wheels. With just a bit of up elevator she broke ground and was airborne. With just 15 degrees of flaps she climbed out nicely. A gentle bank to the right till she was flying downwind and level then climb out to altitude. When I raised the flaps I was surprised to find she needed absolutely no trimming.

She is a heavy bird though. At 17# she flew solid but with high wing loading the landing would mean she would have to come in hotter than I like. So after flying around a bit to get use to her and of course to settle my nerves I began to set up for the landing. I lowered the flaps to the takeoff setting and found she now wanted to turn to the left a bit. I aborted the 1st approach and set up for another try. On the second try she was coming in to hot so with a go around I set up for the 3rd attempt. On this one when I had the runway clearly lined up I dropped the flaps to the landing setting and found she wanted to turn to the left even more. So with aileron rudder and throttle jockeying she touched down. Bounced then touched down the second time and was safely on the ground. The roll out was less than perfect and I ended up letting her taxi off the runway into the grass.

All in all a good 1st flight.

When I checked her out I found that for some reason the inboard left flap stopped working staying in the up position. So with more lift being generated by the right flaps explained why she wanted to turn left with flaps extended. This only made the landing a bit more difficult but manageable.

The CG ended up for me at 112mm and she taxied well on grass and of course concrete. No nose overproblems at all.

Larry Hebert
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Old 06-23-2013, 08:07 PM
  #2007  
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Default RE: CMP BF109F BUILDING THREAD

Congrats Larry!

How did it come up to 17 lbs? Mine's just under 14# dry and flies like a trainer
Old 06-23-2013, 09:24 PM
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Default RE: CMP BF109F BUILDING THREAD

She is actual 16.8 lbs full of fuel.

I am not sure. I tried to build light but I guess every little bit adds up. I do have a complete cockpit with a full bodied pilot. My control rods are golden rods by Sullivan. And I have two servos for the elevator. I'm using power HD servo for the rudder with a pull pull system. I had to add 4oz of lead to the tail to get the CG. 6 servos in the wings pluse 2 electric retract units. Emulation 26 gas engine. And a Dave Platt spinner. I put 2 micro servos in the engine compartment to control throttle and choke.

I will say that the kit parts add up to 13.5 lbs before glue, servos, etc. but even at that I thought I could keep it under 15 lbs. guess I was wrong.

It is no trainer but it still flys well. Take offs are smooth with no bad habits. When I fix the flaps I am sure the landings will be as easy, just a bit fast. She does slow down nicely after touchdown.

With the 26cc engine she is no rocket, but she flies very smoothly.
Old 06-24-2013, 05:57 AM
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Default RE: CMP BF109F BUILDING THREAD

Mine is electric (10s 5000 on power 160) and came out to 16 1/2 pounds with full body pilot
Old 07-20-2013, 05:32 AM
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Default RE: CMP BF109F BUILDING THREAD

I just picked up a open box unbuilt CMP BF-109 arf and it didn't have the instruction manual with it. I was wondering if anyone would sent me a digital copy of it?
Old 07-20-2013, 01:57 PM
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Default RE: CMP BF109F BUILDING THREAD

Somewhere earlier in the thread, I believe it was already uploaded.
Old 07-20-2013, 06:26 PM
  #2012  
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Default RE: CMP BF109F BUILDING THREAD

Hi
Kahlog's correct there is a link earlier, I downloaded it several months ago.
However the scan is not the best as some of the pages have been truncated in the scanning process, it didn't worry me because I had almost finsihed the plane when I lost the manual.
I have now found my original manual and if the copy on line is missing too much I can do another scan for you.

I suggest that you read the earlier threads, most builders (myself included) made many changes to the design particular with the tail wheel, control push rods and location of the throttle servo, the quality and safety of the spinner and engine cooling

Another issue that crops up is that the plane has a tendency to nose over on the ground, if you put the U/C in exactly as per plan the wheels are only 50mm in front of the CoG but it is relatively easy to get them another 30 - 40 mm forward without affecting the appearance or lots more if you make major mods

I found that if you follow the plan and mount the mainplane  then the tail parallel to it they are visibly not square to the tail fin. 
I installed the tail wing first square to the fin and put a thin build up of body filler and silicon under the wing seating to make the main plane square to the tail.
I suggest that you just put it together and look at the alignment before you commit.

One final hint, be careful squeezing the fuslage, the the fiberglass is very thin in several places particularly on the bottom just behind the wing .
 It cracks easy on the tight radius, I had to put a thin layer of glass cloth inside in a few places after I cracked it a couple of times.


Let me know if you need the manual
regards
David R
Old 07-20-2013, 08:04 PM
  #2013  
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Default RE: CMP BF109F BUILDING THREAD

+1 on David's points, the most important one being to replace the elevator pushrod setup with a 2-servo golden rod setup for better handling and redundancy.

Other details:
- before gluing the wing belly put some hard foam or balsa in it otherwise it will warp out of shape
- The elevator tips are lightly built and prone to snapping as a result of hangar rash / transportation, its not a bad idea to reinforce them with some traingle stock (need to lift the covering)

As a typical Chinese ARF it does need some work, but its a great flier and will reward you in the air.

Oh, it also desperately needs a paint job - the 109s were probably the best looking warbirds if you paint them in authentic colours!
Old 07-21-2013, 06:50 AM
  #2014  
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Default RE: CMP BF109F BUILDING THREAD

Hi Aabeylerian   check page 74 of this thread  17/3/2012 4.42 pm from Thomas Pham  for the instructions.

Old 07-21-2013, 04:47 PM
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Default RE: CMP BF109F BUILDING THREAD

Strange.....with mine at 110mm for cg, I don't have nose over issues.
Old 07-21-2013, 06:01 PM
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Default RE: CMP BF109F BUILDING THREAD

You might be right, I haven't flown yet so I cannot speak from experience.  My comments are based on what I have picked up from others in this thread and there have been several comments on nose overs, others have just said keep back stick. 
Old 07-21-2013, 08:18 PM
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Default RE: CMP BF109F BUILDING THREAD

I fly on tarmac (abandoned airport) and my experience is that with CG at 115mm and struts raked slightly forward (2mm shim on rear retract beam) it will not nose over IF it tracks straight.
It WILL nose over as a result of a ground loop especially on take off if I am not quick on the rudder. As the prop spools up and the plane starts to pick up speed, there is a certain moment during the take-off roll when it will viciously pull left. With anticipation and swift rudder input I've managed to overcome it, it did take some practice and a few broken props [:@]

This is very scale behaviour as full size 109s had this tendency.
Old 07-22-2013, 12:51 AM
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Default RE: CMP BF109F BUILDING THREAD

I guess I am confused as CG should not be differant on epower vs fuel ? I understand everyone has there own "sweet spot" and some like more tail heavy vs nose heavy or dead on but CG is CG .
Forward Rake is 100% related to halping advoid nose overs as is how the plane ia balanced but I have never gone out of my way to achive forward rake if it was to dramiticlly change my ability to achieve CG .
Personally I like 25% of Mac as a sweet spot and its never served me wrong .
I can also understand that if you useing glow /gas it may be more difficult to achieve CG vs Epower because of the tank position , but in the end CG is still the same "goal".
As far as the "feel" as Kahlog knows , the Fiberglass on the CMP planes is differant than some other brands but still many have the same flex including ESM . MY ESM Corsair has the same amount of Flex as does my CMP planes . Now I am told that CMP planes have less tolerance to the hot sun , I dont know because I dont allow them long periods of direct sunlight .
I do however reinforce all my glass /composite planes at super flex points on the inside with either FliteSkin or very very light ply .
The differance is incredible and its a simple sand , apply CA and hold , in miniutes your plane feels rock solid with very little weight gain
Old 07-23-2013, 06:01 AM
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Default RE: CMP BF109F BUILDING THREAD

Thank you for all the help guys. I have found lots of great info on this thread!
Old 01-21-2014, 10:55 AM
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Hi Folks, I just opened the box on a Hanger 9 BF 109. Can any one out there tell me why the inboard flaps have that big boxy thing in front of them?
fly 70 man
Old 01-21-2014, 11:04 AM
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Try this:
http://109lair.hobbyvista.com/techre...ng/f_flaps.htm

The internet is a vast resource for your every question~
Old 01-21-2014, 11:24 AM
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That's where the Radiators are on the real aircraft.
Old 06-05-2014, 06:15 AM
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Hey everyone!
I'm having this plane delivered to me today and thinking about engine choices. Since this thing is set up for beam mount kinda limits my engine choices. I'm considering a JC EVO 23. Its got a good amount of power and looks like it will fit perfect in the engine bay. Any other suggestions? Whats the best retracts as well? seems like people are using the sierra giant retracts...is that really the only choice?
Old 06-05-2014, 06:33 AM
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Hi,
Where did you find it, its been long discontinued?

I don't know the engine you're suggesting, I've been using a DLE 20 with 17x8 2-blade that's flying it OK, not screaming fast.
I'm in the process of switching to a MVVS (Evolution in the US) 30cc to swing a 17x10. This being a sleek airframe it will benefit from the 10" pitch to get ~90 mph airspeed and catch the P-51s that have been kicking my butt!

I use ESM 109-E pneumatic retracts, they are a drop-in fit, scale angle and have been very reliable for over 18 months of hard flying. you HAVE TO reinforce the retract mounts though whichever retracts you use.

Oh, and it needs a paint job
Old 06-05-2014, 06:35 AM
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unless they changes the beam mounts they are soft. i removed mine and mounted a saito 150, then a electric. hope to test fly soon.

my point, if you want a firewall mount engine put a firewall in, you will have to replace or tweek what comes in it at some point anyhow.

joe

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