Flight Deck

January 2009

The Carrier Airplane (AMA Profile)

By Eric Conley

Currently the Martin MO1 is the plane of choice for many carrier fliers. It has low frontal area, large wing area, a pretty long tail movement, and enough tail area to give good control authority during the hang or LS (low speed). I've always looked at the MO1 as a rat racer in carrier paint; it is very close to the rat racers I built in the early 1960s. They also make a good plane for Classes 1 and 2 as long as you don't have to put the chin radiator and windshield on the model. Can you imagine a P51 being flown in carrier without a canopy or the radiator under the fuselage? Oh well. With the MO1 you are able to build all your carrier planes pretty much the same. Some profile carrier flyers build CL 1 and 2 planes by adding spacers or bulk heads to each side of a profile fuselage and then sheeting it with balsa and WALA they have a CL 1 or 2 plane. They all fly about the same way and this cuts down on their building time and leaves them with more time to PRACTICE.

After building around a half dozen MO1s the thought of building a seventh was out of the picture. AMA carrier planes if flown well just don't wear out or go away unless you give them to another aspiring carrier pilot. So like many other carrier fliers I started looking around for another plane to build that would be competitive. We have quite a bit of latitude in how we build an AMA Profile plane under AMA Carrier rules 3.3 and As long as the plane we build looks like some type of carrier plane and the judges agree, we're in.

Mike Potter's MO1 passes the deck at Thun Field during the 2006 Stunt-a-Thon's carrier competition. Flying Lines photo.

The American Navy planes of WW2 were all radial engine powered. That configuration has a little more frontal area than I like. So I looked elsewhere and picked the British Supermarine Seafire and the German Messerschmitt 109T for candidates. The Seafire was the Royal Navy's version of the Spitfire, and the 109T was the German carrier version of the famous BF 109. The 109T was the easier of the two to build because it's wing is tapered rather than elliptical like the Seafire's. I built the 109T first, followed by the Seafire and then two more 109Ts. The draw back of the 109T is that no one can believe the Germans ever built a carrier plane. With the Seafire it's that I could not believe I had built that darn elliptical wing. The point I'm trying to make is there are many planes that we can build for Profile Navy Carrier that can compete with the MO1 and at the same time have a much more classic appearance.

When I build these planes (other than the MO 1) I usually enlarge the tail and elevator to help them fly correctly and along with that I may want to lengthen the movement of the tail, increase the wing area, slim down the fuselage, and line up all of these components on the plane to lesson the drag for the all important HS run. As long as we keep all of the major components to the original basic shape and we paint the plane in the color scheme (don't forget the decals) that it had when on duty we should not have any problems with the event directors.

Another nice thing about profile carrier is that the planes don't have to be super light. Built right, these planes can take a good deal of punishment and still come in at 40 to 44 oz. Keep in mind that weight is the killer of HS (lack of acceleration) and the friend of LS (stability) both very important (separately) and a trade off that has to be kept in mind at all times while designing and building the carrier plane. I build heavy in the motor mounts 1/2by3/4 maple, 1/8 ply fuselage doublers from behind the wing spar to the engine thrust washer, 5/32 landing gear, spruce wing spars, 1 by 3/4 medium balsa leading edge, vertical fin reinforced with 3/16by3/8 maple for roll bar effect, tail reinforced with 3/16 by 3/8 spruce, and elevator reinforced with 3/16by1/4 spruce. Actually having said that, I don't build light anywhere on my planes and still they usually come out somewhere between 41 and 43 oz. without a muffler which is well within the ballpark. I use the Nelson Power Thrust Muffler on my AMA Profile planes so I have to add 3.8oz to the above 41 to 43oz figure.

If I wanted to build a radial powered carrier plane it could be done and fly well enough to win or place high in local and regional meets but it would be hard to do well at the nationals where I would probably be flying against a truck load of MO1s flown by veteran carrier fliers. The radial powered carrier plane would have just a touch more frontal area and that could amount to maybe a tenth of a second slower HS and that could be all it took to knock me out of placing. I built a Corsair this year (2006) and took it to Phoenix to the ''Carrier Plus IX'' meet plus I took my latest 109T which I entered in AMA Profile Carrier and as it turned out the 109T turned 17.5 in HS and the Corsair turned 17.84. Remember HS is everything (well almost everything) because the AMA rules (11.2) factor in a bonus on our LS points from our HS points. The faster we go (in HS) the more our LS score counts.

The higher performing planes handle better than the planes that are "sorta" made for carrier (I'm talking strictly AMA Profile rules) and at this time I don't think there are any kits out there for high performance carrier planes. Your best bet is to go to a contest and ask the winner if his plane is available in kit form or plans only, or get in touch with someone who is presently "very" successful in the category of carrier flying you wish to try. When I started flying carrier I got in touch with Michael Pugh who was the president of the ''Navy Carrier Society'' ( NCS ) and asked him if there was any way I could get some back copies of the" Hi-Low Landings" ( carrier news letter). He was nice enough to send me everything he had and that was a BIG help for me. This was somewhere around 1992 and there were many articles in these newsletters that were very helpful. The writer that I enjoyed the most was "Bill Bischoff", Bill could tell you something in the fewest words, and in the clearest form than any one I have ever known. He was the key in my early success in carrier flying.

I've found that the high wing has no advantage over the low or mid wing and feel that the low or mid wing is actually much better than the high wing. An advantages of the low/mid wing is that the bellcrank and lines can be put on the top of the wing behind the fuel tank. The launcher can observe where the throttle position and control the engine speed using the bellcrank throttle arm while on the deck just before takeoff. Another advantage is that it's easier to run out the lines on set up before I fly. A low/mid wing provides a base for getting the bellcrank and line guide exit more in line with the horizontal center of gravity. I mount the bellcrank IN the wing not ON the wing so that the lines are ON the wing (direct contact) not 1/8in. or 1/4 in. off the wing surface. Also I dedicate lines to each plane so there are no lead outs/line connectors at the plane (lighter and less drag I hope). If the lines are 3/8in. minimum off the wing I don't think there is any increase in drag, its only when the lines create turbulence themselves and in conjunction with the wing that drag increases.

When I first started building carrier planes a lot of people thought the wings had to be thick with a blunt leading edge so the stall would be delayed when approaching the hang. I've come to the conclusion that a thin wing with a moderately sharp leading edge gives the best performance in top speed and in the transition to low speed. After all the sooner the wing stalls the quicker we arrive in the hang and that's what we want.

I have toyed with the notion that if I built a smaller (min. wing area) plane that was lighter (36 to 38oz.) it would go faster (better acceleration) and still handle well in the low speed because the wing loading would be roughly the same as a larger plane. I have not had much luck in trying to build a lighter plane so far. I did build two dimensionally smaller planes but they didn't turn out any lighter than my previous larger planes. They did go faster and I chalk that up to their smaller size and having cleaner aerodynamics than the previous planes. As it turned out they proved to be just as good in the LS as the larger planes but only because there was an ideal breeze at the last contest that I attended.

There are many planes that could be competitive in AMA Profile Carrier. Things that I keep in mind when searching for the right airplane is does it have low frontal area or can I build it with low frontal area and still have the plane closely resemble the original. An example is the "Corsair" that can be narrowed down in the fuselage for the least amount of frontal area. An example of the opposite is the "Hellcat" which would be hard to reduce the frontal area to acceptable minimums and still have it look like a "Hellcat".

When I think a plane may be a good candidate I find a decent three view drawing and scale it up to the actual size that I will build too. I then fold the side view of the fuselage down the middle there by reducing the depth of the fuselage. I like to get the overall depth down to less than 4.25 inches. Then I try to line up the engine, fuel tank, and wing on a straight line so none of them present more frontal area than the engine they are behind.

If the plane has a radial engine you need to place the center line of the thrust washer slightly below the center line of the engine cowling. Then if it's a low wing plane the trailing edge of the wing should end up low in the fuselage. I end up with the engine, fuel tank, wing center line being at an angle upward of around 4 degrees to the center line of the fuselage. I then draw in the elevator at the same angle. I then put this drawing in a place where I can look at it many times during the day and see if it looks like the real plane or at least close to the real plane. This can take a while and in the case of the "Hellcat" I never did get it the way I wanted it. If this happens I drop that plane and start in on another one.

I enjoy looking at different carrier planes and making these drawings to see what can be done. The 109T is just about perfect, the prop hub is low in the nose and with the low wing things are easy to line up for minimum frontal area. The Corsair is only a little harder as the prop hub should be near the center of the cowl and the wing trailing edge is low in the fuselage but not at the bottom. The Seahorse (P51) has a high prop hub and the wing trailing edge is low in the fuselage but with the radiator at the trailing edge location it is easy to adjust things so it turns out looking OK. The MO 1's prop hub has a mid nose location, the wing is on its shoulder. The fuel tank ends up behind the engine and below the wing. I find it hard to get things lined up as well as say the 109T.

In conclusion I've found that AMA Profile Carrier (event 321) is a scratch builders paradise. There are many planes that can be used in the event and be competitive with the current plane of choice, the MO 1.

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This page was upated Feb. 11, 2009