hi,I had a os 1.20 on my old cat and it flew great with 14/7 I think it was.Im out of town now and will be back in a few days and will check it and get back to you.I m making a new one now and will put the 1.20 with the 14/7 back on it is very good power comb.
Fred

charlesp
Take a look at the Saito 125 and compare it to the OS 120. The OS120 is 864g (30.5oz) and the Saito 125 is 700g (24.69 oz) and is a more powerful engine. Weight is an issue with war birds so I wouldn’t go much heavier.
I have the Saito 125, Century retracts and all the goodies to put it together but there is a couple of other projects ahead of it.
There is a lot of good suggestions in this thread but I’m just going to it build as is. I have a fiend who has been building for over 35 years, he suggested to build it and not worry about glassing etc. But if that’s what you want to do then do it. As far as the graphics some people think they suck but I happen to like them, which is what attracted me to the plane in the first place, I like that rugged look. Although I may change the numbers just to be different.
Check out this web site http://www.warbirdobsession.com
Hope this helps, Good Luck and Happy Flying!
Shabova
[8D]

I'm only glassing because I didn't like to covering on mine and want to paint it. I do have the clone and not the actual CMP plane though. Work has been progressing on mine but slow. I hope to have some progress to report later this month.

Steve

I agree that its all about weight but there are two historical issues with the CMP and the Flymodels(copy ) the outer wing is not the greatest as far as strenghth and will a lot of flying has been known to fold at the building joint .
As far as weight in the nose , I was wondering if due to its short nose design nose weight would need to be added to achieve CG ???
Does anyone have this answer ?

Thx for the input. With the saito 125 do u have to worrie about it hyperlocking?



----------------------
thx charles

c...p,
I think you meant to say hydrolocking. Were did you hear about this?
Here is the definition from Wikipedia located at http://en.wikipedia.org/wiki/Hydrolock
In automotive terminology, a hydrolock (short for hydraulic lock) is the immobilization of an engine's pistons by a liquid (usually water, hence the prefix "hydro-")). Hydrolocking occurs when liquid fills a cylinder on the intake stroke and, due to the incompressibility of a liquid, makes the compression stroke impossible. This, in turn, prevents the entire engine from turning, and can cause significant engine damage if one attempts to forcibly turn over or start the engine.
I never heard of Saito having this problem, not to say it couldn't happen. Unless you plan on flying in the rain, I don't see how it could be a problem. Yes you have to adjust your carburetor on a high humidity day...less oxygen in the air. There again why would it only happen with the Saito and not an OS or any other 4 stroke?
I admit I am not an engine expert but I just don’t see it. I have a few e-mails out to some people I know who know engines so I will let you know. I suggest you research this a little more.
Good Luck,
Shubova
[8D]

Do you mean Hydrolocking? What I do is always turn the engine over by hand first. If it feels tight, do not turn it with the starter. Take out the glow plug and let it drain, then start it. I can't say I have that problem much though with this plane and a Saito 1.20.

Hydrolocking as was explained is basically in a model engine filling the combustion chamber with fuel causing it to lock up. The most common cause of this is the fuel tank being higher than the carburator. Ideally you put the fuel tank at the same level as the carb so no fuel will gravity feed into the carb. If this isn't possible then there are other ways such as a Kline fuel regulator or turning the engine over backwards at first so the fuel gets pushed out of the cylinder up through the carb clearing it out. Then starting it normally.

Randy

Thx guys hydrolocking is what i was talking about. I just saw somthing on one of the threads about a saito 150 doing that thats why i didnt look at them. Oh and the plane is here now. It looks like im going to have to cover it with sonthing to protect the paing anuone know what i should use? i want to keep ot looking flat so i wont get a shine

I used minwax polyurethane in the gold can (NOT the water based). It is very fuel proof and the spray cans can be found in most stores. The Satin finish is not totally flat but looks good on a warbird. You may get a little yellowing over time, but it does not hurt the look much.

Very good definitions and solutions for the hydro lock problem.
There is one other thing I wanted to mention, if you didn’t already know it. There is difference between the Saito 120 and the Saito 125. The 120 is a very good engine but is no longer made although you can still find them new. The 125 replaced the 120, it is lighter by about 7oz and the HP 2.2 is the same. Also if you compare the Saito 125 to the OS 120 you'll see the Saito 125 is lighter (about 8oz) and is a little more powerful.
Shubova
[8D]

Hot Rod Todd,
Did the surfaces crack when you used the polyurethane. There is two types the one you mentioned and spar urethane. I've used both on wood and they both yellow. The spar yellows to almost a golden brown. Anyway let me know about the cracking.
Shubova
[8D]

No cracking at all. It is actually very clear when you put it on, it just yellows a bit with age. You only really notice it over areas that are white. I have planes that are three years old and it is holding up great.

hay guys is there a set of retracts that i can put in this CMP hellcat without having to cut the wing apart. This is my first warbird and I dont want to take on too much, let me know and a link would help a ton thx

CharlesP, not that I would trust. It really is not a hard thing to do to beef up that area except for the covering. century Jet is the least out of the bunch for mods all you have to do is add quality ply to the spar due to cutting some of the spar away to clear the strut. In this case the covering is not really effected. With care you could make full mods to the retracts if you want and keep the covering. It all depends on your experiance.

Randy

Randy thats what i ws afraid of[&:] Do u have any pics of what it might look like during the mods. thx

I didn't have my camera with me but will bring one home tomorrow night and take pics of one I am building right now and maybe make some sense out of it. The problem but not a bad one is that most of the good retracts are slightly wider than the mount is stock in the wing. Not by much just a little. So you need to widen it. Now if you are recovering the wing or at least the bottom of it or better yet glassing the wing then it is an easy mod. Next when the retract is retracted the spar is in the way of the strut. So you have to make a "U" shape in the spar for the strut to go down into as it crosses the spar. Now that you basically cut half of the spar away you need to beef that back up so it won't break. What I do is take 1/4" ply and cut the "U" shape in it and cut it to the correct size and then use 30 minute epoxy and glue one on each side of the spar making it wider in this area and very strong. Like I said will take pics tomorrow night and it will make sense. Note: if carefull you could do this without screwing up the original covering and just touch it up with some paint and a brush.

Randy

hey guys, I have been working on my cat for a few days in a row,and I need to know if there is much diff.between the cmp and the knock off,I have the knock off this time and dont like it much.I have done alot of work on the wings,should I drop it and get a cmp cat or stay with this one?How dose this knock off fly?My frist one was a cmp and it flew very good.
thanks Fred

Get rid of it, trust me. Its brittle glass work and heavy wood in the wing.

I agree I have seen both side by side and they are not the same quality. I have also seen the fuse back on the stab start cracking on the cheap one.

Randy

hey guys, did some more work on the knock off cat today what a pice of #^&*#@!!Do any of you guys have a cmp cat you would let go cheap, or know where to get one?What a waste of time.
thanks Fred

I'd like to see some pics of yours...

Charles I haven't forgot you will post tonight I didn't get a chance to put them on to much to do at work still.

Randy

Here is some pics of the gear mounts. The area is not final sanded yet but you will get the idea. I doubled up the ribs that the gear blocks are glued to with 1/8" ply. The spar has one 1/4" doubler glued in there will be another on the other side. Rails were made out of Red Oak but any good hard wood can be used. Hope this helps.

Randy

Randy
thx for the picks. It really dont look that bad i geuess. I feal alot better now that i can see what your talking about
thx