Eric Conley's Northwest Sport 40 Carrier plane, flown in 2011, 2012 and 2013 contests, is a Hellcat (F6F) and its top speed is in the mid-60s mph. Eric Conley photo.
A 2013 dustup on NW Sport 40 Carrier
By Eric Conley
I think this is the third year for Northwest Sport 40 Carrier and it seems to be doing quite well as carrier events go these days. To date it has been flown not only in the Northwest but in Southern California and in Arizona.
In Southern California, Ron Duly is leading the charge, having had S40 as a official event in 2012 and in 2013 at several contests. In Arizona it was an official event in the Carrier Plus Contest in November 2013. Everywhere the planes are flown they attract commits from people to the effect, I have to build one of those or I have a plane I could convert to fly that event so the talk part is going good and I'm hoping some of these people come through with a plane and if they do I know they will be happy with the results. I think this event is the greatest thing to come along for me since I first saw carrier being flown in a WAM Championship Contest held at Corning, Calif., back in the early 1990s. I was sold on carrier then and am now sold on this event. I'm going to talk about my take on this event so far and will start with the planes I see, and the plane that I have flown in the event so far.
I have found all of the planes interesting that I have seen from the 2011 Northwest Regionals to the 2013 NWR. They were all shapes and sizes in 2011 and haven't changed all that much in 2013. I'm thinking the prerequisites for a plane that will give the best chance to place in a S40 event are as follows.
Here is what you have to start out with: OS .40 FP or a Tower .40, both in stock condition, running a stock carburetor, equipped with a stock OS muffler for these engines. Keep in mind these engines do not have a lot of power, this is very important. Then you have a pretty large selection for a plane limited only to a minimum of 300 or more square inches of wing area, no method of changing the lead out position in flight allowed, but movable control surfaces are allowed. So we start out knowing that we haven't got much power to play with so we will need as light as possible plane that has as little frontal area as we can get away with and as much streamlining as possible without adding to much weight.
So here is where most of the people who fly S40 will part from me in how they go about setting up a plane to fly this event. When it comes to carrier planes, they are the only planes I've built since the early 1990s and of those only one was from a kit. After building and flying my first carrier plane (the kit) I started going by the rule that the strongest engine coupled with the lightest, cleanest plane will provide you with the best chance of winning or placing in a carrier event. Only one thing changes when you start to fly S40 and that is the engine, which is close to the weakest engine you could use. That is the only difference.
So lets start with what is light and what is heavy. 38 to 42 ounces would be the light planes. Light planes give you good acceleration off the deck which will help you score high in the high speed portion of the event. The light weight plane will bounce around in the low-speed portion of the event but will still give you the best chance to do well. 43 to 48 ounces would be a medium weight plane which is OK but does decease your chance at a good score by being a little slower in high speed, a good flyer in LS but not the potential to score better than a light plane. Then we have the heavy stuff from 49 to 56 ounces and I only mention 56 ounces because that is what Burt Brokaw's plane weighs and he can squeeze out a pretty high score (the highest score) because he hangs his plane in the low speed portion of the event, picking up a lot of points there. To get his plane off the deck he uses a 11x5 prop and it just does get off with no room to spare. His high speed scores are usually in the mid to low 50 mph range so he loses points there but as he says, it's the only Sport 40 that I have.
My current S40 plane weighs 43 ounces and with just a touch of air coming over the bow of the deck it jumps off the deck and I have to be quick to not let it climb above 6 feet. I built this plane 5 years ago as a training plane for AMA Carrier events powered by a Thunder Tiger Pro .36. It has a flat-bottom wing so it could be built on a flat table without any sort of jig and was never expected to go faster than 70 to 80 mph. It turned out to be harder to build than any of my 109Ts so I never built any more and had hung it in the garage to gather dust until I saw my first S40 event and I knew right away it would do well in the S40 event. This plane has a wingspan of 40 inches, fuselage wing cord of 10.5 inches, tip cord of 7.5 inches, wing area 360 square inches. The depth of the wing (thickness) at the fuselage is 1-3/16 inch, and the tip depth is 3/4 of an inch. The engine, tank, and center depth of the wing are all lined up to lower the frontal area to that of the engine. I'm using a Pylon SS 6 fuel tank but think that a tank with 3 ounces of capacity would be plenty to complete the S40 event unless you plan to do a lot of hanging which I hope you won't. The propeller I use is a APC 9x6 sport prop which is the same as I use on all of my AMA carrier planes. I don't think you can buy a better prop for this event but if you do, please let me know.
How about the landing gear, which is very important and often over looked in S40? I've seen a few stunt planes flying in S40 with stock stunt style landing gear (low to the ground) along with a tail wheel mounted on a long gear leg to allow it to make those beautiful stunt take offs and then land with no bounce and a long roll out. In carrier you want neither of these. The tail of the plane should sit as low as it can without snagging the arresting hook. The nose of the plane needs to sit high enough that the plane can leave the deck with no up elevator. This is very important for the simple reason you don't have any excess power so you can't hold up elevator causing drag and adding pressure to the tail skid causing drag (friction) and then as the tail leaves the deck it goes down and hits the grass or the plane balloons up into the air and has a slow first lap. So remember, tall landing gear, low tail skid and no up elevator on take off, level off at 6 feet. Now lets talk about where the center of the main landing gear wheels are compared to the center of gravity, or to make it simpler, where the wheels are compared with the crankcase of the engine. The center of the main landing gear wheels should be ahead of the backplate on the engine crankcase and can be clear out near or under the prop. This placement of the wheels will help ensure that the plane does not go over on its nose while making an arrested landing on the deck.
Speaking of arrested landings where the plane doesn't go over on its nose, lets talk a little about carrier airplanes and the pivot point of the hook. When I first started flying carrier almost all of the arresting hooks were hinged on the bottom of the fuselage and stuck out of the back end of the plane 5 or 6 inches. It was released by a pin from the throttle arm of the 3-wire bell crank or by up or down elevator releasing it with an auxiliary pushrod connected to the elevator pushrod. I wanted to use the arresting gear to pull the pin at the slider that released my lines and allows the slider to slide back to point the nose of the plane out of the circle. With the arresting hook pivot at the bottom of the fuselage it was hard to get enough leverage to pull the pin because the pull was almost straight in line along the bottom of the fuselage. So I moved the pivot point of the arresting hook up to the middle of the fuselage and also moved it forward to just behind the trailing edge of the wing. Now the hook didn't stick out behind the plane and everything looked cool to me except my plane started tipping over on its nose every once in while when landing on the deck with the arresting gear.
A good carrier friend told me that I should move the pivot point up a little or move it further back on the fuselage. I moved it back a couple of inches and shortened its length enough so it still didn't stick out of the rear of the plane and had no more trouble with it going over on it nose. A lesson in geometry solved the problem. There are 2 much simpler ways to build the hook that I see every so often. The first is just let the hook hang down at about a 45 degree angle; it doesn't have to be in the up position on take off and the mechanism to hold it up for just a little while can be a pain to install. Do be sure to have some down tension on it so it will not bounce up when contacting the deck skipping over the arresting lines. The easiest way to add tension is with a rubber band connected to the hook shaft and then to the bottom of the fuselage. The all- time easiest way to add a hook is to make the tailskid a hook. As the hook faces forward in these two instances as the plane travels down the deck the end of the hook should have an inside eye bent into it so it won't catch on a small imperfection on the deck. The eye can be fine tuned by twisting the eye sideways to lower its scooping ability.
How about some out thrust to keep those lines nice and tight? There are 3 ways to do this, one is give the engine some out thrust at the nose of the plane. My current plane has around 7 degrees of out thrust at the engine and maybe 2 to 3 degrees through the lines at the wing tip. That is 2 of the ways to add out thrust and the third one combines the 2 as I did. My plane will only hang in under 2 mph air and that's OK with me because I don't want to hang in this event. The plane that I just finished for S40 will start out with no engine offset and no line offset. I won't be able to test this plane until April so won't know how that will work out. I'm thinking that it will need some engine offset to keep the lines tight when crossing the upwind side of the circle, so we will see.
Now, for the people who don't cherish the thought of taking out their current bellcrank that is probably buried in the wing and installing a 3-wire bell crank and linkage to the carburetor, there is another way. You set the plane up to use the newly allowed 2.4 radio and receiver systems. You won't have to touch the buried bellcrank, pushrods (flaps and elevator), and leadout's. You will have to install a small battery, small receiver, and one small servo. Only the servo has to be mounted by screws or bolts (I prefer screws) because it will have a pushrod to the throttle arm of the carburetor. The receiver and battery can be left floating around inside the wing between the fuselage and the first rib out from the fuselage on the outside wing, also the servo will probably be located in this same bay. You will need some type of hatch on the top (preferable) or bottom of the wing so you can retrieve the battery for charging. I looked up the price (Brodak's) for a 3-wire handle, 3-wire bellcrank and 3-wire lines, it came to $103.00. The price of a transmitter/receiver, 1 servo, and battery came to $100.00 (Horizon Hobby, RC Lips Inc). I would imagine that you could get the same RC equipment from Hobby King for half that much.
I'll give you my 2 cents worth on converting a sport plane or stunt plane to S40 and at 2 cents I may be overpaid. Remember, weight is our biggest enemy, then comes frontal area, and then clean lines (streamlining). I don't know of any sport or stunt plane that doesn't have a wing that is at least 1 inch thick and stays that thick all the way to the wingtip. I do know that they have a class of racing plane that is based on the Flying Clown, and they turn some pretty good speeds with a plain-bearing engine. Also my friend Burt flies a plane based on the profile Clown in a speed event down in Arizona, they are turning in speeds of 140 mph (Nelson combat engine) with a 300+ square inches wing area and the wing has to be a full inch thick its entire span. They are built with a minimum amount of frontal area, are streamlined to the fullest extent (1.5spinners, no cockpit, and weigh only 25 to 30 ounces). These same planes with a TT Pro 36 are turning 110 mph. So look for a light 300+ square inch wing area plane that has low frontal area and could be streamlined easily. So you have to cut the wingspan down some; it will just be lighter and faster. So don't let one of these hanger queens keep you out of the event. If you find you have questions on anything in this article, PLEASE ask them in the Carrier Forum in the Flying Lines website. That way more carrier fliers will get the same information and more information will be shared. I will be writing a following article on what I like about this event, how I approach a flight in a contest, and how I prepare for flying this event. So stay tuned and I hope to see you at a carrier deck sometime next year.
At upper left is Eric's 2014 plane, with its low frontal area and clean lines. Other photos show details of the bottom and electronics. Eric Conley photos.
This page was upated Dec. 3, 2013