I am fixin to drill the holes for the engine and was wondering if it mattered if I centered it rather than having it ofset? I have a GP spacewalker and the motor is wayoff from what it is suposed to be and I was wondering if this plane would be ok? I am putting an OS 90fs on it and wanted it inverted instead of sideways. If it dont work that is fine I was just wondering. What is more important, the left to right or up to down?

if your facing the plane you normally want a little left and down thrust. because torque is opposite of rotation.

The firewall should have the thrust lines already on it. They are setup for the required amount of side thrust so just center the engine on the lines.

if you face this plane it is to my right and up on the firewall. I know about those lines but I was wondering if it would make any difference if I moved it to the center instead of to the right? i have that spacewalker I was talking about with a G20EI and I had to make it fit and it is way moved over. I had to just make it fit without any reguard to the lines at all in either direction and so far it flys great. But this is a cap and I wanted to make sure it didnt effect it.

bubbagates can answer that one better than me

Just set it up by the lines.

Go fly it and go straight up. On the way up do not correct it for anything but make sure the wings are level before pulling up and do not change the power settings, just let it slow up. If the plane goes straight up without doing anything the engine thrust angles are correct and you do not need to change anything but this will not be likely. I have yet to see any plane that did not need adjustments.

If the plane goes to the left, add a washer on each bolt between the firewall and engine on the right side when facing the plane from the front
If the plane goes right, add a washer under each bolt between the firewall and engine on the left side when facing the plane from the front


Now fly it straight and level at about 1/2 throttle into the wind and suddenly chop the throttle, if the plane drops the nose suddenly add a washer to each bolt at the bottom between the firewall and engine. If the nose goes up suddenly add a washer to each top bolt between the firewall and engine. If the plane slowly drops the nose it's fine

The idea is to get the plane to track as straight as possible using the engine thrust angles. trying to set it up before hand is tricky at best because the engine torque, prop diameter and pitch all contribute to how it tracks in the air

As I said before, the lines are already setup for thrust based on the recommended engine/prop range. If you change that to a bigger engine/prop combo then you will have to make adjustments after you mount the engine and fly it

I typically spend 20 to 50 flights getting a plane properly trimmed. I have never seen a plane yet in any size that did not need some work. About the best one I have seen so far is my Comp-ARF 3.0m Extra 260. I set it up exactly like the book using exactly the recommended equipment including engine but a different prop and though I did not need a click of trim anywhere to fly straight and level, I did need one degree of right thrust because I used a different prop which caused the plane to pull ever so slightly to the left jsut as it started to slow going straight up

thanks a heap bubbagates, that is just what i was needing. Man I didnt know there was so much stuff to keep in mind. just proves you never stop learning. thanks again!!!

no sweat crashland. What I suggested most people will not do. I learned a while ago that it's much easier and more fun to fly a plane that has been trimmed correctly plus during those trim fl9ight is when you really get to know the plane.

I compete and since it's hard enough to remember wind correction and a host of other things, the last thing I want to do is fight a plane through a maneuver that is out of trim.

The Cap you have is really nice. Keep the elevator throws low. Do exactly what the book says for the throws no more. It will not look like much but the elevators on any Cap are extremely powerful and if setup with too much throw will cause an unwanted snap at the wrong time, especially at any speed.

I'm not trying to scare you at all, I'm a huge Cap fan and in almost every case of someone complaining of a snappy Cap, it can almost always be traced back to to much elevator throw at too fast a speed. Caps are not meant to fly fast, in fact they do there best thing which is a tumble, at very slow speeds

Here is a video of RCU member whaturi flying a GP Cap232. This was my old one which snapped the front clean off in an off field landing. I gave it to him and bought myslef another one and he loved it

http://www.hafsonline.org/video/vincentcap.wmv

How would you compare a cap to a 300s extra 40 size? I have one of those.

Never flown or had one, sorry

Another question, how about having an engine inverted compared to sideways? Would it make any difference? I would rather do this, that way I wont have to make any unsightly holes in the cowl.

Hey Crashland 73,
One thing you may want to consider. Most people I know don't like to mount 2 stroke engines inverted because they are sometimes hard to start and hard to get a dependable idle. The reason for this is the location of the glow plug. With the inverted engine, the glow plug is in the bottom of the engine which makes it easy to flood it when starting. I have seen an Ervine 61 two stroke engine in a spacewalker mounted with the glow plug at +/- 225 degrees (looking at the front of the plane). This keeps the glow plug from always being in fuel. It also cuts down on how much cowl destruction you will have to do.
Also, rotating the engine will not change the engine thrust, meaning you still would need to do what bubbagates suggested about trimming the plane.

Regarding your question about the Cap VS Extra, They are both excellent flying, aerobatic airplanes. The only drawback with the Cap is that they can sometimes be touchy with the elevator, meaning the airplane will smap out of a turn or loop if you pull too hard on the elevator stick which could have disasterous concequences if you are not high enough or if you are not ready for it. Of course if you fly at least 3 mistakes high while you are learning about how the airplane reacts to your inputs, you shouldn't have any problems. I hope this helps.

Hey Bubbagates,
I for one agree with you. I would also prefer to take whatever time needed to trim out my planes to get them flying straight and true, but I get the same grief from other pilots you do. What drives me crazy is that the more you get into making small changes, the more the changes will affect things you have already corrected.

Fly safe and have fun!!!
David

hrrcflyer, i am putting an os 90fs if that makes any difference.

I've actually converted a few. I met one guy at a club I just joined. We both had the exact same plane with the exact same setup minus the brand of servos, he flew mine and turned right around and changed engine thrst at the field. He then went home and shaved the wing saddle, etc...

I've had others fly my stuff and comment on how nice they fly.

It's a bit of work, but well worth it in the end and it can also prolong the life of the plane because you end up with one that is very predictable

Any engine can be run inverted, it's a matter of tuning. Most problems with inverted engine can be traced to the low needle being too rich

It's harder to tune one that is inverted because even a tun of 1/8th inch can make a huge difference. I tried something when I flew glow and it worked for me. Run a fuel that has a higher oil content. This will allow you to lean it a bit more and still get oil into the engine. Again you still have to be careful of getting it to lean