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Wednesday, March 23, 2011

Extreme Flight Extra 300 EXP__Clean Sheet

Greeting to our friends from who are looking in on this report. Welcome and please check out the other articles here.

The original Extreme Flight 45" Extra 300E was a ground breaking airplane. Along with Extreme Flight's 45" Edge 540T, it pioneered the 45" 3D ARF class, and set a new industry standard for quality and performance. Those planes were everywhere, and since they kept selling out, Extreme Flight had to keep on making more while the competition learned from their design and closed the gap.

 Eventually,  the Extra 300E was surpassed by the newer designs. So much has been learned since the original Extra 300E design that it would no longer be enough to update the plane. What was needed was a clean sheet of paper, and that is exactly what Extreme Flight started with for the EXP series.

Knowing how Extreme Flight does things, I was not at all surprised that the EXP series are another step along the line in 3D airframe evolution. The big surprise is how different that are from their predecessors. It is almost like they are something, well....something completely different. Let's be very clear here .... there is nothing left of the old Extra 300E. Everything on this plane is brand spanking new. Extreme Flight threw away everything they had, and replaced it all with something better.

OK, maybe Extreme Flight carried over the wheels, and maybe a bolt, a nut or two, but everything else is a brand new piece that is designed and made better, stronger and lighter than Extreme Flight has ever done it before.

I have also owned the Edge 540T EXP and currently fly an MXS EXP, so I am very familiar with the EXP series and how they are put together.  While this review is about the Extra 300 EXP in particular, much of the innovation we will talk about is specific to the entire EXP lineup.

Since the flying is always the most important part of any review, we'll start with that, and then follow up with an in depth look at the new construction and material innovations that make the EXP such a special series of airplanes.


If you read my MXS review you will have seen the word "different" used a lot in the flying section. That's because the MXS series flies differently from what I have been used to, and the Extra, while tamer and more precise, flies in a very similar fashion.

The EXP series is even different visually. The horizontal and vertical stabilizers are  bigger in proportion to the rest of the plane than we are used to seeing, and the control surfaces are enormous. I am guessing Extreme Flight made the EXP series as stable as they possibly could with a huge wing area, big tail surfaces and long tail moment. Lots of stability generally works against agility, but Extreme Flight got that back with huge control surfaces and big degrees of movement.

The Extra wasn't designed to be quite as wild as the MXS, and with a little more stability built in, it is more smooth, precise, and gentle. I find the MXS to be easy enough to fly, but the Extra seems a little friendlier and a bit more forgiving. I'de say the Extra is much better for a newer pilot and the MXS would be the next step. I guess we kind of got out of order here because it would have been better to review the Extra first and then move on to the more advanced MXS. There are just too many good planes in the EXP series to know where to start.

Both airplanes do everything well, so the differences between them are subtle.  I find precision maneuvers to be better with the Extra and wild 3D is better with the MXS, so they are two different planes built for two different purposes. You can fly decent enough IMAC with the MXS, and I have, but the Extra seems just a little better suited for it.

I really enjoy drawing big lines with the Extra, and working on my point and slow rolls. I like flying the Extra as precisely as I can because that's what it likes. Fly the extra smoothly and it will reward you by making you look good.

With a full 88 degrees of elevator deflection, the Extra's pitch authority is startling. We've had a lot of good laughs at how instantly the MXS will go utterly flat in a parachute, and the Extra is nearly as spectacular. The Extra has a slightly longer tail moment, which takes away a little pitch authority, but you get back pitch stability in return. The Extra has enough of both, so it doesn't really give up anything here. For most guys, it is just fine the way it is, whereas the MXS has insane pitch authority that newer pilots simply don't need. Trading away a little insanity to get smooth stability is what makes the Extra a bit better plane for the newer pilot.

One thing I plan to try is a triple rate so I have my precision rate, an insane high rate, and a medium rate with full throws except the elevator cut back to 50 degrees or so. I've found that I get a better harrier if I concentrate on using less elevator stick, so the mid rate could be the ticket for everything except the crazy tumbles, waterfalls, walls, parachutes and such.

Thing is, we have never before had this kind of elevator movement to play with, so it is all going to be a learning process. The planes become more and more capable and the pilots remain the weak link. So much of 3D is about understanding what the plane is doing and why, and with the EXP series that cerebral process is starting for me all over again. This is just part of becoming a better pilot, which I am always working for.
Using the set up in the manual for the ailerons, I've found the roll rate is exactly what I am used to. Because the controls are so big, you have good roll authority all the time, as long as you have a little power blowing air over them. I've found as long as I have enough air going over the plane to hold it up, the ailerons won't stall.

The Extra has a very powerful rudder which makes tight harrier turns a breeze. I'm still working on the Chris Hinson "donut" move, where he spins the plane in a flat  horizontal 360 turn, but I'm not that brave yet. KE coupling is minimal, though I'm running a 3% up elevator to left rudder and 4% up to right rudder mix. I'm still dialing it in, but that's where I ended up with the MXS. That's where I started with the Extra and it is pretty close.

The side force generators (SFG) come into play really big in knife edge flight. The nice thing about these SFGs is they give you enough additional lift to rotate the nose up confidently when you are low to the ground. I've been cutting my KE flight pretty close lately, and I've got to blame these SFGs for making me so confident! When the ground is coming up, you want that rudder to be able pitch the plane up, and the SFGs give you enough extra lift to make that easy.

KE with the Extra is more like conventional flight on it's side than the foreign thing it used to be. I mean, it's still not completely natural for me, but it's much easier with a plane that likes it so much. The SFGs give so much stability and yaw control that I've now got a lot of confidence in KE.

Not only does my field have rolling terrain, but the city is doing so much construction that I have to fly up and over trees, dirt and mulch mounds, and construction equipment. The stuff gets moved around every day, so it's challenging to get a good knife edge game going. The SFGs are so effective and help the rudder so much that I simply fly around the stuff and go up when I need to go up, and dive when I need to dive. I've got enough rudder control, so I am learning to do this.

With the monster SFGs, the Extra's harrier flight is really stable. I didn't get any sort of wing rock, and both elevator maneuvers parachutes are dead solid. Some people will say the jury is out of SFGs, but I completely disagree. They definitely make the plane fly better, and that's all I really care about. Some people don't like the way they look, but the Extra flies fine without them. Leave them off if you want.

The Extra had no nasty surprises for me. It was just smooth, stable and predictable. I know I have said that about a few planes lately, but all the planes from my favorite two manufacturers are getting to be so damm good it's hard to find anything to complain about.

In general, the Extra EXP is great 3D plane, but the part that impresses me the most is it's grace and precision. There are wilder planes out there, but I don't think that's what you want from this plane. While it's wild enough, the Extra is still easy and reassuring to fly. I think the Extra EXP would be an excellent 3D trainer, and with a good sport set up (which we will develop shortly) the Extra would make a great trainer for conventional aerobatics too. No doubt, the Extra is a fantastic go-to plane. 

I'll continue to enjoy this one, but I also want to pick up another one for the closet. This is just one of those planes you never want to be without. Already got a blue. I'm thinking red.

EXP Design and Construction

When the rumors of a new series of Extreme Flight 48" planes began to surface, I tried to hound Chris Hinson for as many details as I could get out of him.  He didn't want to give away too much, but he told me that every single aspect of design, construction and performance was going to be critically examined so as to find a better way of doing things and delivering a better flying plane, a better looking plane, an easier assembling plane and a more rugged airplane.

No big deal, really. We're just going to reinvent the airplane, that's all.

We now know that he was talking about things like geodetic construction and extensive use of composite materials, innovations that have never been seen on planes in this size before. There are also other features such as the control surfaces being designed to deliver a whopping 90 degrees of travel and still maintain a very small hinge line gap.

Let's start at the front and work back.  The firewall and forward part of the motor box is reinforced with Extreme Flight's exclusive G10 composite material. This is very stout stuff that is still very light. It's not quite carbon fiber, but it's very close and not so expensive that the plane becomes unaffordable.

Of course, carbon definitely has it's place, and the firewall is braced with carbon longeron tubes from each corner to the first bulkhead in the fuselage. This makes for an extremely rigid motor box that will not only take a lot of abuse, but will also waste less power by flexing, and instead send it to the propeller where it belongs. I am not sure it is bulletproof, but it certainly looks the part.

A nice touch is that the firewall is pre drilled for Torque motors, but of course. There's no screwing abound with measuring, drilling and installing blind nuts. You just bolt your Torque on and go fly. There are cooling holes cut in the firewall right behind the rear air exits of the Torque motor, so the air goes straight in, and comes straight out with no restriction. I have flown Torque motors in a lot of planes, and they definitely run cooler in the EXP series planes. I'm guessing the way the air flows through the motor, out the back, and unrestricted through the firewall helps this a lot.

Moving back to the battery compartment, under the battery tray is the landing gear mounting block, which is made entirely out of good old G10 composite material. Again, this is strong stuff and I have tested it pretty rigorously on more than one occasion. Lots of 3D airframes fall woefully short on strength in this area, but not the EXP series. I imagine you could probably break the plate out in a big enough impact, but you'de have much bigger problems by then!

In this picture, you can also see the carbon rods that brace the fuselage sides. These run all the way to the tail, so that is a lot of expensive composite material stiffening things up.

Also in the battery compartment, notice the G10 reinforcing around the wing bolt holes, and wing tube mounting brackets. There's lots of stress on these parts, and using G10 to keep it all together is a strong, lightweight solution.

Also, on the MXS, G10 is used in the reinforcement around the holes for the wing anti-rotation pins. This is an area subjected to constant stress, and after enough wear on a material like wood, the holes can wallow out and allow the pins to move around. This lets the wing move around, and then you can forget about having a precise flying plane. Nothing loose on an airframe is good, especially if it's the wings, so using G10 in this critical area keeps the airplane tight and the wings aligned. You'll have a more precise flying plane that stays that way for longer.

Also note the anti rotation pins themselves are carbon rods, so you'll have a hard time wearing these pieces out too. It's expensive to use carbon, but if you restrict it to the areas it will help the most, you greatly improve the rigidity  and durability of the plane without driving costs off the scale.

There are a generous amount of carbon stringers used to brace and strengthen the length of the fuselage. You can clearly see the long carbon rods bracing the turtle deck, and lower are one that braces the fuselage side, and another that acts as as a stringer. These carbon rods run from just behind the  first former all the way to the tail of the aircraft.  These weigh next to nothing, but they definitely stiffen things up, and a stiffer airframe flies more precisely.

Now that we're at the tail, let's look at geodetic construction whole purpose was to make stronger vertical and horizontal stabilizers, and stiffer control surfaces, while saving weight at the same time.

Don't laugh. this is the best picture I could get without ripping the covering off the stab!

Extreme Flight succeeded in this because even with the Extra's long tail movement, the tail is so much lighter that the plane will balance even with relatively lightweight batteries in the nose. So, now we have saved weight in the tail, and in the nose.

The stab, fin, elevators and rudder are built up, but there is minimal sheeting because structurally it isn't needed. The geodetic construction makes the surfaces strong and rigid without the sheeting, thus cutting weight down.

Looking at the elevator and stab, notice the deep hinge line bevels.  This allows you to get a monstrous 90 degrees of elevator travel and still run a tight hinge gap. Normally control surface travel on these smaller planes is limited by the need to keep a small hinge gap, but with the deep bevels, we can now have both.

Having built both the Edge 540T EXP and the MXS EXP, the Extra build didn't have any surprises for me. Every brand has it's own peculiar way of doing things, but I'll admit the EXP series is extremely similar to what I am used to. A lot of things are done the same way, and I believe even some of the hardware are the exact same pieces. This is good because it's all top of the line stuff.

The aileron linkage couldn't be any easier. Screw the ball links on both ends of the push rods and then bolt the ball links to the control horn and servo arm. I always use Dubro 2mm hardened allen bolts simply because I like the way they look.

In the only complication of the entire build, I had to snip approximately 1/16" off one end of each aileron push rod because they were too long. I like this because it means the threads are buried so deep into the ball links that it would be almost impossible for them to pull out.

By using the long single arm that comes with the HS65MG servo and cranking the end points on my transmitter, this is just the perfect amount of aileron for my flying style.

One place we deviated here was using an HS85MG servo on the elevator. I was getting blow back and stalling on my 48" Edge EXP, and since the 85MG is specified and works so well on the MXS, we decided to try that on the Extra. We only had to trim the servo opening a little bit, but it was worth it because this is a big upgrade. The 85MG simply refuses to take no for an answer, and you get instant full deflection even in moves like full throttle walls and terminal velocity parachutes. With the 85MGs greater torque, you will be able to bet the most out of the Extra's generous elevator authority. Maybe with this kind of control I'll have the confidence to bring back the Z bend landing.

Again, ball links on both ends of the push rod gives you a nice, tight connection that is free of slop, but with smooth, drag free operation. First class set up.

One thing to be careful of if you choose to go with the 85MG servo, check the servo arm clearance to the stabilizer before you drill the holes. You may have to drop the servo down a bit so it doesn't hit. Ours fit, but it was close.

Dual Ball links on the rudder linkage gives a nice, smooth action and full travel, with excellent centering.

As you can see, I got away with using the standard arm that comes with the servos, and on the elevator I used a High Tech 85MG with the long durbo arm. Like this I didn't get a chance to try Extreme Flights' most excellent G10 servo arm extensions. I was a bit disappointed because they are simple, functional, well engineered and well made pieces. I always like to use stuff like that. Hopefully I'll get a chance to try them on my next project.

Here is a close look at Extreme Flight's exclusive G10 servo arm extension. I used Durbo self tapping button head screws to attach the extension to the standard Hi Tech arm and then ran a bead of thin CA all the way around the arm to lock it down really tight. The kit comes with two of these, one for rudder and the other for elevator. These arms give you as much throw as you'll need to make the Extra stand up and bark.

As of this writing I am satisfied enough with the rudder response. The Extra can do full throttle knife edge loops without needing full deflection, so I don't think I need any more. Initially I was worried about blow back simply because the rudder is so large, but I have a secret weapon in the new Airboss 45 ESC that now runs the servos on 6 volts. The little 65MGs scream their guts out on this much voltage and torque is much improved. I need a little more time to fly the plane and see what we have, but as of right now I don't see a need to change the rudder servo out for an 85MG.

Radio Gear Installation
I really like the way the radio compartment is laid out in the EXP series, simply because it's easy to get a clean install. I put the receiver when the manual says, run the wires up through the slots cut in the tray, and it came out perfect. There is no scientific proof that a neat and tidy installation makes a plane fly better, but I sure feel better about it when the install comes out this clean.

A nice touch is the holes for mounting the switch are pre cut. What's nice is that all of this stuff is already thought out for you. Just put the gear where the manual tells you and everything comes out perfect.

Power System
Using the Extreme Flight power system with Torque 2814 motor and Airboss 45 ESC makes for a clean installation.

Here I glued a balsa block to the motor box and velcroed the Airboss 45 to it. This location puts the ESC right in the cooling airflow coming into the cheek cowling. Also, like this, it is in the right position so the switch can be bolted to the mounting holes that come pre cut in the fuselage sides.

We have always used Thunder Power batteries exclusively for all our projects, so we had a good supply of 3s 2250 and 2700 Pro Power 30C pack on hand that worked so well in planes such as The Edge 540T EXP and MXS.

While the Extra was designed to run on either 3s or 4s, this last year I have been flying my 47" class planes primarily on 3s, aiming for that magic 180 Watts Per Pound  figure.  While I am generally too lazy to do the math, I have a good feel for what I like, and all three of the EXP series planes (Extra, Edge, MXS) that I have owned fly beautifully on 3s. I've tried the MXS on 4s and it will continue that way, just because it's so bad ass. The Extra, however, I plan to fly more smoothly and gently on moderate power. It just seems really sweet like this to me.

With the lighter 2200 pack, the plane balances fine with the battery where you see it, and I'm flying the heavier 2700 pack a little further back. There is more room to go back if we needed to, but using the CG location specified in the manual (balance on the center of the carbon fiber wing tube) we are dead on. 

As well thought out as this entire series of planes seem to be, this was certainly no surprise either.

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