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Tuesday, January 31, 2012

More Extra__And Installing The HS85MG Servo On the Elevator

Last week I retired my beloved red Extra EXP, which has been my primary beater since wrecking my original blue Extra EXP. I have made so much progress with that plane. Whenever I would stick to just that plane for a week or so, I would always learn something new, or something I would be having trouble with would suddenly make sense.

I was so comfortable with this plane that I would try anything with it. For the longest time I thought the Edge and MXS were slightly better 3D planes, but once I started pushing the Extra deeper and deeper past the stall I learned how to get more out of her and she 3Ds better than I had ever dreamed. The learning process always seems to step up a notch when I fly the Extra.

Mostly I nailed down my precision a little better with this Extra, but I think she helped me raise my entire game. What a great airplane she was, but I had put so many hard flights on her it was time for something new.

I am especially pleased that she has a good new home with a guy stepping up from another brand, and will be flown hard daily.

Unfortunately I also trashed my blue MXS a few days later, so now I am down two planes with the flying season right around the corner, but the good news is my replacement red Extra EXP got here yesterday.

Today's ARFs, especially EXPs, are so nice and so complete that even a crash is not so bad any more. You hate to lose a good flying plane, but with a quality EXP you can be back in the air in a couple of days. Sure, some guys claim a couple of hours, but I don't know anyone who works that fast and doesn't have stuff falling off the plane.

This will be an in-progress kind of report. I may come back and update this report, or maybe even file a new one, but either way. I'll keep everyone up to date on how it's going with the latest Extra EXP build.

Installing the HS85MG Servo On The Elevator
The EXP series was designed to operate on the Hi tec HS65MG servos, but we soon found out with the quantum leap in airframe performance that we were asking too much for that servo on the elevator.  The MXS has always been set uyp to run the larger and more powerful HS85MG servo, though the Exta and Edge will benefit from that too.

The first step is to make sure that you do not move the servo output shaft forward or backwards. The push rods have a finite amount of threads, so if you get the servo in the wrong fore/aft location, you might end up with a push rod that is too long (fixable by snipping off a few threads) or too short (not fixable without a longer push rod).

Drop an HS65MG into the elevator servo hole, and mark the location of the servo output shaft on the fuselage with a magic market or felt pen. When you install the 85MG, you want the servo output shaft to line up with the mark you just make.

Next, line the 85MG up over the hole and guesstimate how much you will have to cut the opening to make the servo fit in the proper fore/aft location. As you can see, I simply laid the servo over the hole and then cut away the covering. From here we got lucky because to keep the output shaft in the same place, we just need to open the servo hole rearwards.

Now that the fore/aft location is locked in, let's drop the servo down. We do this for two reasons: first is that the servo is too wide to fit, and second, we need more space away from the stabilizer so the large Dubro servo arm we are going to use has clearance and doesn't rub on the bottom of the stab.

Here I use a straight edge to cut a straight line, and then I go back and drive the blade in deep. You can see there is a balsa block on the fuselage bottom and that needs to be relieved so the servo will sit down.

I tried really hard to get a good picture but this was the best I could do. You can see how I notched out the balsa block fuselage bottom and now the servo sits low enough. Seal all the covering edges down with a trim iron, and on mine I ran some CA in to seal the wood and lock the edges of the covering down. 

Lastly, here is the finished servo installation. You will have to dry fit the stab and servo with Dubro arm installed to make sure you have enough clearance, but I've done these before and I am confident opening the hole downward enough to get the servo in also drops it down enough.

One final trick is to push the servo as rearward as it will go in the servo hole. You probably won't get it absolutely perfect and will have a little slop, so move that servo backwards and that means you will have to turn the ball link further onto the push rod to get the elevator centered. One or two or three more threads going into the ball link is more margin against the push rod pulling out. You might even need to snip a thread of two off, but that's a lot better than not having enough threads on something like the elevator. 

As of this writing I don't have the stabilizer in yet, so I am going to cheat a bit and post a picture from my beloved and late, original blue extra EXP. You can see how important it is to have dropped the servo down because of the tight clearance the servo arm has to the bottom of the stabilizer.

I am using the longest arm in the Dubro pack, and the ball link is bolted to the second from the outside hole on that arm. I cut off the overhang of that last hole to get a little more clearance, but you can see it is still pretty tight. All my extra EXPs have been set up exactly this way and they have all flown beautifully.

Wednesday, January 11, 2012

60" Extra EXP__More Of A Good Thing

After just over a year of flying the 48" Extreme Flight Extra EXP, I couldn't wait to get my hands on the new 60" variant. The 48" has been my go-to plane from the minute I flew my first one, so I knew a bigger version would truly be more of a really good thing. Everything else being equal, bigger planes generally fly smoother, more precisely, and more solidly than their smaller counterparts, and the 48" Extra is already smooth, precise and solid enough. It was hard to imagine how good the big one could be, but it actually exceeded my expectations.

The biggest surprise was the first one, and that is the 60" Extra EXP is very floaty. Previous experience with big vrs small planes led me to believe the larger EXP would be heavier feeling, less responsive, and need more power to stay up, but the opposite was true this time. Its not quite like a foamy, but it flies much lighter and slower than any of my 48s. Having had a chance to fly the 60 Edge EXP, I was partially prepared for this, but you can see in the videos that I can drag it around at a crawl and it doesn't want to drop out of the sky. It's light flying nature is very impressive.

The other surprise was how responsive all the controls are. Tim Semerero warned me that 31 degrees of aileron is enough and anything more is hard to keep up with. I ended up flying it with 33 degrees, and figured I could aways turn my end points back if that was too much. This turned out to be totally unnecessary as 31 degrees gives you wicked response. I have since set the plane up to deliver 31 degrees of throw with my end points pegged at 150%, and now it's nearly perfect, if maybe a tiny bit fast. I can deal with it because I like it that a big plane can be so responsive.

The same is true on the elevator. I take great pains to hinge my 48s so that I can get the full 90 degrees of throw. This is because as compared to the Edge EXP and MXS EXP, the smaller Extra gives up a little pitch authority. The 60" version, however, pitches extremely hard on the 60 degrees that Tim recommended. It's not as crazy as the 48" Edge, but for a big airplane it is very definitely impressive. Maybe after I get a few nicks on it I'll want to get crazier with it and need more elevator movement, but for now it's fine the way it is.

At high speed it tracks like a pattern ship. Straight lines are actually pretty close to as crisp and easy as, unbelievably, a Vanquish. I really did not expect this from a large scale aerobatic plane. Slow and point rolls are easier and cleaner than ever before. I work hard on those with the little planes, which has paid off big, because they are almost too easy with the 60" Extra. As part of that floaty thing, the big Extra doesn't seem to drop as much in slow and point rolls, so you need a lot less rudder and elevator correction. This would make one heck of an IMAC practice plane, and it is easy to see how the larger Extreme Flight Extras have done so well in competition.

Knife Edge is made easy by the big SFGs. I was sort of expecting this because they are very similar (if not simply scaled up versions) to the ones on the smaller EXPs, and those are KE monsters. As of yet, I have not set up a KE mix, simply because it does not seem to need one. It doesn't tuck either direction.

Timing on snaps and spins is a little different, but it doesn't take long to adjust your style. At first I was under rotating a little, but once I got used to it, I was hitting them just as cleanly as with the little planes, if not a little more accurately.

I have not done much in the way of tumbles yet because I have had bad luck breaking planes of this size, but the few snaps and such I have tried have been utterly spectacular. I have every confidence that this will be just as tough of a bird as the little EXPs, but being a new plane I am content to sneak up on the really violent stuff. This is a considerable investment as compared to a 48"s and I am taking my time with everything because it has to last at least until the 60" MXS gets here!

Again, once I get a few nicks on her I won't care so much and we'll see if I can get it to sling the wheel pants off in a blender. You can see an easy blender in one of the videos, and it was really, really pretty, falling into a slow, beautiful inverted flat spin. What a lovely flying airplane!

I am taking my time dialing this plane in, but outside of turning the ailerons back a bit, I have not had to do anything. I haven't even played with the CG yet. I think it's pretty close, but mostly I am just enjoying the plane so much that I don't feel compelled to improve it. Either that, or it came off of the workbench perfect.

Overall the big Extra flies very much like it's smaller 48" sibling, though more smooth, solid, reassuring, and more floaty. I have always felt like the 48" Extra was the ideal airframe in many ways, and it has been the standard of performance that I use to judge others by. Now, the 60" is better in almost every aspect, except maybe it is not as easy to transport as a smaller plane. Can't have everything, I suppose.

Sport settings
I generally do not ever use my low rates, but on this plane I wanted to get a head start on the sport settings. I dialed my low ailerons back to 25%, though I think to get those three rolls in five seconds I will need to cut it back to 20%. On the low elevator, I am at 30%, but I hate to cut that back any more for fear I will forget which rate I am on and try something stupid like a parachute.

We will probably not do a dedicated sport report with this plane, simply because I like to go full tilt with a new dedicated airframe and there are just not the resources for me to do that. I also don't want to tear this plane apart and put a new set up on it. Still,  I will put my throw Gage on it and give you my rates in degrees, which I think is the easiest way to set a plane up.

You can see in the following video,  that toward the end I tried the low rate and it looked pretty close to what you would expect from a sport plane. It was smooth, stable and very gentle, just like the 48" Extra EXP Sport. The difference with the big Extra is that everything happens much more slowly (unless you have the hammer down) and you have a lot more time to think about what you are doing. The thing is just a big, giant teddy bear.

Power System
There was never any doubt that the 4016 would be the motor of choice for this project. I had used one before on another 57" plane and was really pleased with it's smooth, cool running. However, that was on 4s, so I wasn't really getting near the motor's potential, nor it's peak efficiency. On 6s the thing just breathes pure fire and it truly goes like stink. It's very impressive to see a 60" plane move out like this thing does. I am thinking it is about the same speed as a 48" Extra, or maybe just a little quicker. We will try to use a friend's Iphone Doppler feature to get a reading, but I am sure it is gonna be fast.

It is almost not worth talking about the Airboss 80 we used simply because it is like it is not even there. I buttoned up the cowling and that is probably the last time I will think about it until the plane is used up. With an Airboss, you just plug it in and forget about it, and they always work perfectly. I have many smaller Airboss units that have hundreds and hundreds of flights on them, and the most work I have ever put into any of them is to wipe them off between switching them from a worn out or crashed plane to a new one.

It has been awhile since I have flown an Airboss 80, and I sort of forgot that it's responsive is even better and more linear than the Airboss 45. That, or maybe the bigger Torque motors are just like that. I had almost no trouble porpoising in my hovers like sometimes gives me headaches with the 48"s. I just grab what I need and the motor stays there. I don't have to chase the throttle at all, unless it is to correct the plane getting knocked around by the wind.

I don't want my speed controller to sing, and I don't want it to dance. I just want it to work, and I always get that with an Airboss. No other choice was ever even considered.

Battery Performance
Having had such good results with my Thunder Power 4s 2700 65C Pro Power packs, I wanted to stay with the Pro Power 65C series for this plane. We went with the 6s 3850, and while initially I was afraid those might be too large and heavy, it was not a concern at all. Seeing so many guys having success with 3300 packs, I thought I had made a mistake, but the Extra is still really light, even carrying around another 500 mah more than most other 60" Extra EXPs.

Exactly as I was expecting, the packs performed brilliantly, delivering smooth, explosive power, and cool running. I was getting 25.33V on a full charge, and after 5 minutes I was coming down with 23.10 to 23.20 volts. With 22.2 being the rated voltage. This gives me a really impressive safety margin. The more voltage you leave in the pack, the easier it is on it.

I am pretty sure I can get a full six minutes easy, and maybe even more. However, after 6 minutes of hard extreme aerobatics, I am pretty wrung out and start making some serious mistakes, simply from being tired. You gotta know when to quit.

I could get some smaller packs, but that would involve money, and I am not sure I would want it to be any lighter than it is anyway. It is really super floaty.

Again, I also like having a little bigger margin so I can take better care of my packs..... just another case of more of a good thing.