RE: CMP 120 Zero ARF Build thread
 

Nice wheel that on left side. I have little Robart (like on your right picture) but will not mount it. Not enough room to put retract and servo or air cylinder, and I am trying to avoid pushrods.
Will go with fixed, but steerable tail wheel. I have something like this on my Thunderbolt and it is working well. Need to make one more part and then will post pictures.

RE: CMP 120 Zero ARF Build thread
 

Good points there Frets, 30mm tire is exactly 1/5 scale according to Dave Platt. I came up with 25mm for our plane and that is the exact diameter of the stock wheel supplied in the kit! It is small, but the Zero had a small tail wheel, so the full scale wheel easily fits in my hand! That thing is $18 and you are probably right, it is of low quality, but give it a shot, if it works it would look great.

Room for the retract mechanism is a problem, so I'm following Dave Platt plans. I sized them to fit our plane and built the unit. I could not find one on his web site and I'm not sure how his was constructed, but I just used mostly PC board and it came out pretty cool. Still have to add some balsa and filler to make it the scale shape. Interestingly he uses the air cylinder as the shock, and it worked great on his plane so I'm doing the same thing. The benefit besides simplicity is the low profile of the unit. Mine with the extra brass still attached, is 1oz in weight. I am sure I can use carbon tubes in the stab and save an ounce or even more. But I will save the weight back there somehow!

RE: CMP 120 Zero ARF Build thread
 

Frets, yes that's a very nice tailwheel (pic on the left)!
Where can I get one?
thanks
V.

RE: CMP 120 Zero ARF Build thread
 

hay guys my cmpro 120 size zero is just about finished running in eng atm just need help on the c.g point on this modle iv seen some points but just wanted to find out from some one who has finished this modle

ta

RE: CMP 120 Zero ARF Build thread
 

,
Frets - I didn't see any answers to your question above....the "double cone" is a venturi...a simple means of creating vacuum required by some instruments. Obviously although simple and effective, it did create drag. More advanced aircraft early in the war changed to an engine driven vacuum pump. The coffee can is likely the oil cooler as the air intake is on the port side below the venturi and the engine coolant radiators are under the fuse, (barely visible in your photos). Hope this helps.

RE: CMP 120 Zero ARF Build thread
 

I always thought the "coffee can" was some type of turbo booster ...:)

RE: CMP 120 Zero ARF Build thread
 

Hi guy's,
Apologies for just disappearing off the thread over a year ago! It wasn't that the model had crashed or anything like that:) I was just having a lot of domestic difficulties and didn't have any incentive to do anything slightly modelling related. Things have settled down again for me, and I'm back in the game!
I test flew my Zero a couple of weeks back and a guy at my club shot a bit of video. It's nothing exciting, just a take off, few circuits & a landing, all done with the wheels down because it developed a problem with the retracts on take off. The RCV 120sp wasn't running to It's best, but still haulled this 14lb model off the ground suprisingly quickly! and hauled it around the sky at a more convincing scale speed with that nice big 18" x 12" three blade prop. On the second flight the engine got so hot it blew the end cap off the silencer, lost back pressure and stopped about 40' off the deck going down wind! I managed to turn it 1/2 way back to the strip, but my buddy called to just keep it straight and flair it in to the crop. When we found it I couldn't believe there wasn't a single bit of damage!
I've now closed off most of the cowl and put some ducting in to direct air straight down through the engines fins. I'll try it again over the weekend and see if it has improved the engine reliability.

http://www.youtube.com/watch?v=AuzoN...&feature=feedu

Walts.

RE: CMP 120 Zero ARF Build thread
 

Well done WALTS. Congratulations. Where did you set CG?

RE: CMP 120 Zero ARF Build thread
 

Thanks Misha034. I set my C of G at 145mm and it still needed a little down trim to hold the nose down. With the RCV 120sp It required 9 oz of lead screwed to the bottom of the engine mount block. Got it charging for tomorrow,....Lets hope the weather is good;)

RE: CMP 120 Zero ARF Build thread
 

Nice work Walts....i've got a 16x10 to try on my crrc 26R when i eventually get her flying again in the next few weeks. Going from 18x8 to 18x10 2 blade really cut the noise down and i'm hoping a 3 blade will bring it down some more as its a bit borderline at our club. Yous looks well balanced as you have it...i suspect a bit of down thrust would do wonders on our planes as mine needs a bit of down elevator too but i'll just get it flying first. (its been in repair since November). I'll try to post a vid of my own once its flying again.

RE: CMP 120 Zero ARF Build thread
 

Thanks Shuglu, I really want to grab a decent video of this model once the engine is sorted properly. I had hoped to get out today to re test the new engine cooling, but it's just too windy here. I'm kinda lucky with my new club that noise isn't an issue. At my old club they hated my RCV SP's because of their high noise levels! Good luck with getting yours sorted again, and I look forward to the video;)

RE: CMP 120 Zero ARF Build thread
 

Well guys my pc has crashed and is out for repair as a result Im subjected to posting on here via smart phone which doesn't seem to allow me to post any pic
Anyway a quick update and pic to follow as soon as Im able.
Exhaust is plumbed and routed correctly, in addition i cut the cowl and re did the cowl flaps hinged and glued to the interior of the cowling from thin sheet aluminum this allows a much easier solution to get the clearances needed for the scale exhaust
i went ahead and cut out the forward section of the simulated metal plates on the fuse and replaced them with actuall thin sheet aluminum also some other detailing on the fuse and the cowl (rivets deeper panel lines and a few other unexpecte details )

stay tuned

RE: CMP 120 Zero ARF Build thread
 

@wats, you have attaches me to computer, waiting for that video.

@Zero, hope you will fully join us soon.

finally I have finished a part that, so far, gave me the most trouble.
Tail wheel. Because of the earlier (read - bad) experiences with a one servo motor for the tail wheel and ruder,
I decided that rudder will have its steering (standard servo) and the tail wheel will have stronger metal gears servo.

When I created all, and then tried for function, as one of may friend use to say , "I cut 3 times, and measure once" I have glued rudder,
and connect commands. For commands I have used fishing nylon (Thank's Mirce).
Nylon I snuck through clevis

http://img143.imageshack.us/img143/909/dscn2277r.jpg

At the end I tied the knot and melt it in order not to untie.

http://img14.imageshack.us/img14/8863/dscn2278v.jpg

Another end, and the result was

http://img829.imageshack.us/img829/7774/dscn2280u.jpg

Of course, I could connect it directly to the horn, but it seemed like a more elegant case in case of need to detach command.
On the part where the tightening circuit is (allen screw) bar is flattened.

http://img855.imageshack.us/img855/7978/dscn2281o.jpg

In reason to prevent comannd lever to bend, although made from 4mm steel,
I made it little longer and made the upper part to go thru the ply that will carry the tail wheel.

http://img855.imageshack.us/img855/1257/dscn2282.jpg

On these pictures you can see how nylon is attached to servo

http://img863.imageshack.us/img863/6460/dscn2284.jpg

http://img843.imageshack.us/img843/1068/dscn2289v.jpg

I found some unused tail wheel (of course for Piper CUB), plastic, but it is easy to make it a little stronger if needed.
Shaft is 5 mm thick.

http://img193.imageshack.us/img193/7359/dscn2294n.jpg

http://img268.imageshack.us/img268/4332/dscn2295ot.jpg

The command for wheel is horn, which is fixed with two beams on ply.

http://img840.imageshack.us/img840/3880/dscn2296a.jpg

http://img689.imageshack.us/img689/8427/dscn2297s.jpg

Since the ply, that factory has planed for this purpose is only 3mm thick, I have glued another ply 4mm on it and then fixed gear mount.

http://img801.imageshack.us/img801/8810/dscn2298i.jpg

http://img59.imageshack.us/img59/5987/dscn2299a.jpg

http://img684.imageshack.us/img684/3787/dscn2301l.jpg

Since Servos (for rudder and wheel) that I have connected with y cable are not from same manufacturer, of course, they are working in the opposite ways.
Solution is either Y cable with reverse or simple receipt that I used, crossover cables. I crossed rudder cable and
Now the wheel and rudder are turning in the same direction.

http://img705.imageshack.us/img705/6285/dscn2303.jpg

Control throws are not the same and the only way to control it is length of the servo's command lever.
For now, wheel has a larger radius than rudder.

RE: CMP 120 Zero ARF Build thread
 

Zero 322, I finally remembered to take the camera to the field so I got a picture to the Zero. I've been having trouble with the Robart RS 701 air up, spring down retracts since the first flight. They continue to occassionally fold up on landing. Work fine out of the plane or in the plane up on blocks on the ground. Often will land and while rolling out one of the gear will just fold. Finally out of frustration, I replaced the retracts with a set of Spring Air retracts which I had gotten for another project then not used. They are Robo Strut ready for 3/8" struts, so I drilled them out to 7/16". Not a lot of metal left but I hope enough. Flew the airplane last week, and have eight take offs and landings with no failures. May be taking the Zero to a Warbird fly next week end, depending on the weather at Andover, NJ.

RE: CMP 120 Zero ARF Build thread
 

Misha034, beautiful work on the tail wheel and rudder/tail wheel cables. Great job.

RE: CMP 120 Zero ARF Build thread
 

Well buddy that's is most defiantly going on the wall! I especially like the exhaust staining

i feel your pain on the retract just another example why i refuse to go any other way other than electric trouble free and truly plug and play, what's not to like?

RE: CMP 120 Zero ARF Build thread
 

http://www.airborne-models.com/html/...asp?AGroupID=9

See post #764, pg 31 this thread for other links as well

RE: CMP 120 Zero ARF Build thread
 

Thanks for the info. This helps a lot in deciphering "correctness" on a lot of artist renditions and clears the decision making process as to what to include or exclude detailwise based on model and time period.

RE: CMP 120 Zero ARF Build thread
 

that horn shapedvalve is the exact samevalve the use on a Mc 202 & 205's with the DB605 engine. its a boost blow-off valve.
its designed to bleed off pressure if the manifold builds to much pressure.

hope this helps a little.

RE: CMP 120 Zero ARF Build thread
 

RBean, how is that Ryobi doing in there? You do have a ryobi 31 cc in there, right? I would like to do the same with mine... could you offer a few tips you learned in your installation? Thanks!!!

Rich

RE: CMP 120 Zero ARF Build thread
 

So is this why you have not answered my PM? I will be patiently waiting for your response.

misha034, definitely looks like a sturdy tail wheel and rudder installation, although I am not sure if the fishing line will hold in the clamps, maybe it will but I would use small cotter pins at the ends.

Finished my tail wheel.

RE: CMP 120 Zero ARF Build thread
 

Firepoweor RC, the engine installed in my Zero is a converted McCouglah 25 cc with electronic ignition with a custom muffler that I bought off a club member. It runs good and turns a Master Airscrew 16-8 three b lade prop 8,000 rpm. With the Zero you need weight in the front so no reason to pay for a new powerful light weight engine. The engine weights 52 ounces and I still needed to use a heavy hub and put both batteries as far forward as possible and still had to add some weight. Here are some pictures of the installation. Of interest, I have a DLE 20 installed in an H9 Hellcat which turns the same prop at 8,450 rpm.

RE: CMP 120 Zero ARF Build thread
 

WOW. That tail wheel looks astonishing.

Hope that nylon will hold. Same system on my Thunderbolt has around 200 flights

RE: CMP 120 Zero ARF Build thread
 

Thanks!

Proven system, can't argue with that! :D

RE: CMP 120 Zero ARF Build thread
 

Hey bud sorry for the late response i was finally able to access your pm

i did look and the viking kit i have isn't complete however as i said i don't see having a use for it, your welcome to what's there, from what i can tell the side panels and instrument panel is missing that and the seat but the seat and yoke I've used on mine, forward me your address and ill send it out "its on me"

Gorgeous tail wheel assembly mabey when i get to that point you'll be good enough to give me a how to?