Modeltech Cap 21 ARC?
 

I just picked up one of these for a really good price and was wondering if anyone had any experience with it? It has a 59" wingspan and calls for a 40-50 2-stroke or and 60-90 4-stroke. I know that it may be a snaping machine but for what little I have invested in it I thought it could be a fun project. Does anyone have any tips on building it or "finishing" the rest of the plane. The instructions are pretty vague and leave alot to the imagination. It does however have a after market glass cowl and some really nice hardware. Thanks!

RE: Modeltech Cap 21 ARC?
 

Your comment about the instructions is an understatement! They're horrible! But if you've built other planes before, you should have no trouble figuring it out. The hardest part I found was setting the firewall with the proper right and downthrust. It fits in there perfectly when it's in the right position, but I had the impression that it was too tight and was tempted to carve it down, which would have made it too small. Fiddle with it a while to get it right.

I built mine pretty much stock and covered with monokote. Used an os61fx with a pitts muffler. It has a real tendency to snap, but that can be controlled by holding down the elevator movement. I was worried about the strength of the gear, but had no problem with it. Overall, it flies ok, but I sold mine after about six or seven flights because I wanted to move on to other planes that fly better. The guy who bought mine flew it about six or seven more times, then demolished it in a high-speed dive. We're not sure why the plane crashed, but one of the control horns was broken and he thinks it's inflight behavior just before the crash was consistent with that horn breaking. It's been several years now, so I'm not sure if it was elevator or rudder.

Here are two photos. The scheme is just something I made up. The large lettering from the kit is installed across the bottom of the wing:

RE: Modeltech Cap 21 ARC?
 

waagbuck,

You had a sharp looking plane there. I do have some more questions and hopefully you can help me out. It calls for a Y pushrod for the elevator, do you think I should go for this method or join the elvator halfs with music wire and just run one pushrod towards the back? Also just how snappy are these things? Are they so bad that there not flyable? I'm thinking if its that bad I might just sale it and get a diffrent plane. With the stock gear did you have any nose over problems on grass? What kind of performance did you get with your 61 and how did it up balancing out? One last thing, did you use those odd plastic pieces for the wing bolts or did you go for another method to hold the wing on? Thanks for your time.

RE: Modeltech Cap 21 ARC?
 

Thanks for the compliment. I always thought it looked sort of lackluster given the fancy covering schemes you see on arfs and nicely built kits.

I used the y-pushrod. I joined it together right after it left the servo with two heavy-duty wheel collars. I copied this method from another plane, and it worked out fine. I never really liked joining the elevator halves on a high-performance plane.

It snapped performing an inside loop the first time I flew it. When I reduced the elevator throw, that problem went away, and the only real performance issue was the high-wing loading, which meant I had to keep it moving quickly to avoid a stall. It's definitely a flyable plane, but it's not in the same class as some of the newer superlight designs that have come out. I don't think you'd ever find yourself doing 3D maneuvers with it. As to whether you should sell it and move on, that's up to you. Given that I have the sickness for getting new planes and a wife who notes how many I have, I got rid of it.

No nose-over problems in the grass. Just keep on the elevator like any taildragger.

Performance was excellent with the .61fx. I used a 12x6 prop. I remember adding about an ounce to the firewall, but that was about it. Didn't fly it enough to experiment with it more tailheavy. I did drill some lightening holes in the elevator and the rudder.

I used the stock wing-mounting bolts (black plastic things). It took me a while to figure out how to install them correctly (having not seen this type of thing before and having no instructions), but I figured it out. It's difficult because you have to line them up along the longitude of the plane, and then set the proper rotation to match the angle of the wing bolts. And of course when you set the wing in you can't see a thing. I remember making a template that allowed me to drill the holes in the wing.

Good luck!

RE: Modeltech Cap 21 ARC?
 

Thangs again waagbuck!

Do you have any pics of your y-pushrod? I get an idea of what you are sayin but need to see it to actually comprehend it! I may run a K&B 65 or or a 91-4 stroke in it. I need to decide so I can set the firewall in at the right point.

RE: Modeltech Cap 21 ARC?
 

Just happened to have one of these in the box (from a friend) and one that is vintage 1982 with well over 2000 flights..Stripped the covering and it was pink all over. Well with the new one in the box I got the saw out. Here is what I am going to do.
Lighten-Rudder, elevator, horizontal stab. Swiss cheese the fuse from foward wing saddle back. Mount mini servos in tail for rudder and elevators. Cut rib sections into the wing (did this to the old one and stacked 80lbs of weight before it started to crack) noticeable weight savings when holding wing with one side uncut.
Finally I will shift tank to CG and pop a Satio 72 up front.
My origonal flew with a small ST 60 1980 vintage, still have in box. I think that with the 72 and a larger diameter prop it should be fun.

Post some pics, and keep the speed up till you get use to it. It will fly slow but you have to be on top of it at all times, unlike todays 3d machines.