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-   -   CMP Spitfire MK2 71" 90-120 Build (http://www.rcuniverse.com/forum/nitromodels-support-456/8957855-cmp-spitfire-mk2-71%22-90-120-build.html)

dditch 07-23-2009 12:45 PM

CMP Spitfire MK2 71" 90-120 Build
 
Here is a link to the kit I speak of:

http://www.nitroplanes.com/spitfire120.html

Manual posted on RCG
http://www.rcgroups.com/forums/showa...mentid=2530363

Existing threads on this plane:
Old review : http://www.rcuniverse.com/magazine/a...article_id=117




dditch 07-23-2009 01:04 PM

RE: CMP Spitfire MK2 71
 
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Overall, the build went well with some bumps in the road. Kit is built very well and is a solid Warbird. Solid meaning heavy but tough.
Fiberglass fuse and wood built up wing. Scale looking covering.

Some Photos of the parts in the kit.

dditch 07-23-2009 01:37 PM

RE: CMP Spitfire MK2 71
 
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Building the wings is just like in the manual.
Here is a link to the retracts I purchased from Nitroplanes. they fit right in.
5mm diameter wire.
http://www.nitroplanes.com/prmenore.html

They lock in pretty tight with little or no wiggle.
They fit RIGHT into the pre-existing mounting holes.

I decided to take the advise of some people and purchased Oleo spring struts from RCwarbirds.com

I initially built the kit with the Retracts and included tires and molded wheel wells. I fly over grass that is REALLY clumpy and can get long in the spring.
The first test flight is like in my photos, but later,I pulled out the molded wheel wells then opened up the wheel well and made bala cavity myself so I could install bigger 3.25" wheels. The opening was 4" so even if my landing gear bent, I could get the gear to raise.
I'll show photos of my initial build first.

Building the wing. I found that the way they did the retract mounting was pretty stout. They upgraded how they did it compared to the original design of the kit (someone at my field had the older version). I did not feel the need to beef up the retract mounting considering I had the Oleo Struts.

dditch 07-23-2009 02:05 PM

RE: CMP Spitfire MK2 71
 
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I decided to go ahead and make the flaps move even though I was warned they were not very functional. They really are not and do affect the landings but don't really help.
Instead of soldering them, I used wire and JB weld to put the wire splitter together. I measured it all out after installing the servo, put it in a vise, slopped some JB weld on it then wrapped it w/ wire then put more JB weld on it and let it sit overnight.

dditch 07-23-2009 02:16 PM

RE: CMP Spitfire MK2 71
 
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Retracts, I've only done a couple Retract planes before and used Mechanical on this build. I know that people will tell you that Mechanical retracts require alot of re-adjusting. Yup, they often do. I used a Hitec low profile retract servo. you MUST use a retract servo as standard servos are too tall/deep to fit. Just measure the amount of travel that the retract moves and then pick a servo arm where the holes 180 degrees apart match that distance.
These are the Oleo Struts I used.
My photos do not show it but since these are larger diameter, I had to dremmel out more room for them to sit into the wing.
I had to remove most of the 'stem' of the wheel well.
As mentioned, I later removed ALL of the wheel well and covered it with Balso then painted with krylon paint.
http://www.rc-warbirds.com/product_i...roducts_id/625




dditch 07-23-2009 02:36 PM

RE: CMP Spitfire MK2 71
 
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After flight #10, I noticed the bottom half of the internal firewall was delaminating. With nothing clamping it down from the front and the power of the YS 1.20 I was using, it was causing the engine mount to be able to rock downwards as the firewall would bend. I fixed that by simply adding some wood onto the front. For good measure, I added some balsa reinforcement using epoxy into the inside. I roughed up the fiberglass then cleaned it before adding the blocks. I trial fit them and numbered them before gluing in. I mention this now because now is a good time to add the reinforement into the inside. Wait to do the fire wall plates later AFTER you install the outer firewall plate and know where you have room.

dditch 07-23-2009 02:44 PM

RE: CMP Spitfire MK2 71
 
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In Step 12 for the wing mounting holes, they tell you to drill 75mm from center. If you do, your likely to drill all the way through and hit the wing part that flairs out and cut a hole in the fuse. If you do drill through, protect that fuse or drill a little closer in. I drilled at 60mm. Even if you do 75mm, it may be hard to fit that blind nut in that far out as well.

For the horizontal stab, the slot cut out in mine was about 1 mm larger than the thickness of the horizontal stab. I pushed mine down then after it set, I filled in w/ thick epoxy one side at a time. This took a while since I had to let the epoxy harden up 3 times.

I masked up the fuse so epoxy would not flow onto it.

dditch 07-23-2009 02:47 PM

RE: CMP Spitfire MK2 71
 
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Be warned, step 14 shows the dimmensions for bending the tail wheel incorrectly.
Look at where you will be putting the hinges, then look at where you will be putting the tail rudder control horn.
Then look again at how far in you will want to bend the tail wheel wire. 20mm is too long I recall.
Measure twice, bend once

For the tank, I added a cross brace to hold the tank down. In my photos the tank was out more and back more than where I ended up with it. In the end, I pushed the tank all the way up so the cap was sticking out just like in the plans. But I though I'd show how I held the tank in.
I don't see how the tank would stay unless you added something to hold it down.

dditch 07-23-2009 02:56 PM

RE: CMP Spitfire MK2 71
 
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Step 19 Engine mounting. One thing to look at is that the fuse has some built in right thrust and down thrust. Upon initial flight, the built in right thrust was fine. But the down thrust was not. After the maiden flight, I added a single washer to the back of the bottom 2 mounting bolts between the black plastic engine mount and the fire wall to point the engine upwards more.

dditch 07-23-2009 03:03 PM

RE: CMP Spitfire MK2 71
 
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For the Cowl, make sure you push it back far enough for your spinner to not contact the cowl. My inital flights were w/ a 2 blade 16x8 prop and an all metal spinner that is even w/ the prop washer front face. After the first couple flights, I switched to a 3 blade 16x8 master airscrew and plastic spinner. The plastic spinner sat further back and I had to make a cowl adjustment for it.
I added a scale pilot figure I purchased from hobby city. I also added the machine gun dust covers (red squares) and some lines onto the wings to get a more scale appearance.

I have a vinyl cutter so instead of using the included markings, I chose to try to match up with P7350 marked ast XT-L. This plane still flies in an airshow in Brittain.

Pictures when I finished before the Maiden flight (2 blade prop installed)

dditch 07-23-2009 03:10 PM

RE: CMP Spitfire MK2 71
 
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Photos w/ the 3 blade prop. I used Krylon for plastic to add the yellow on the blade tips.

dditch 07-23-2009 03:22 PM

RE: CMP Spitfire MK2 71
 
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Here are some photos on the day of it's maiden flight.
You can see by the thickness of the grass (in the spring) where I fly, why I put bigger wheels on it later on.
Some guys at my field prefer to fly w/ fixed gear and then put the oleo struts on them.

SunnyFlyer09 07-23-2009 06:27 PM

RE: CMP Spitfire MK2 71
 
Good job ditch. It seems like some of the scale lines are wrong, too bad they could'nt make it more scale looking

dditch 07-24-2009 06:33 PM

RE: CMP Spitfire MK2 71
 
Yea, not exactly "scale", more like "funscale"
I should add that I moved the CG up to about 10cm FORWARD of the suggested range. So I'm nose heavier than they suggest for the most forward CG. (110mm)

Maiden flight.
[youtube]http://www.youtube.com/watch?v=3QGrJOPqs-o[/youtube]

A6TEXAN 07-27-2009 11:29 PM

RE: CMP Spitfire MK2 71
 
can you tell me what the cg on the plans are ? thanks.

dditch 07-28-2009 02:33 PM

RE: CMP Spitfire MK2 71
 

Quote:

ORIGINAL: A6TEXAN

can you tell me what the cg on the plans are ? thanks.
The manual states 120-130mm from the leading edge.
There is a link to the manual in pdf form in the first post of this thread.
I don't have an exact measurement of where I have my CG now but my test flight in the youtube video is at about 125-130mm
You can see the "pitchyness" in the video.
It was noticably better when I moved the CG up some.


Pit-Viper 1 10-01-2009 06:47 PM

RE: CMP Spitfire MK2 71
 
Glad to see they fixed the CG after my experience. CG used to around 95mm, and talk about a hair raising flight. It went nose up as soon as the wheels left the ground, everybody thought it was going to crash including myself. Managed to get it in minus the fixed gear. Now it's been 3 years since it's second and final flight, it was underpowered and the gear tore out again. Since then I've sheeted the wing except around the gear area until I figure out what gear I'm gonna use. Then I'll glass it and paint. Does anyone know who makes a descent air retract for this plane? Don't want to go too expensive but not too cheap. Love the video, congrats on the maiden. We took video of mine but haven't been able to locate it.

Thanks Shane

rebranger 10-12-2012 09:33 AM

RE: CMP Spitfire MK2 71
 
Anybody know where to get a DECAL SET for this plane?


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