Lucky Lindy (oz10910)
About this Plan
Lucky Lindy. Free flight power model for .15 engines.
Quote: "This remarkable free flight twice won a place on America's International FAI Power Team! Here at home it has been flown by both new and experienced contestants with outstanding success. Lucky Lindy, by Larry Conover.
There were two reasons for calling it Lucky Lindy. First, it is a way of saying - Howdy Mr Lindbergh, and thanks. An appreciatior of his contributions to aviation. Also, after seven years of Wakefield trials (but never the team) I was looking for some secret to sucess. I thought - If you look through all the old books you might find something.
Well I did and it was in 'How to Construct A Flying Model Aeroplane.' 1930. There was a picture of three proud winners with their models. Boldly lettered on each was the title 'Lucky Lindy'. So, there is the secret!
Six Lindys have been made in this area of Iowa. Each has the same built-in adjustments. They all have very similar flight patterns, They adjust easily, and are not a one-man-airplane.
The original was flown for two years as a 19 & 23 combination. In early 1956 it weighed in at 21 ounces with a Torp 15 at the FAI Power semi-finals in Galesburg, Illinois. It made the grade, and while the model was in England a sister ship and wife Dotty's Lindy flew with great success at the Third King Orange Internationals. At the 57 Nats in Philly four Lindys were flying. Three of them placed in the top money. The old original was flown in four events.
For the new HEAVYWEIGHT FAI rules I built in a ballast box under the CG. The Ship seems to be an ideal size for the 28-1/2 required weight (for area). It captured a place on the 1958 American team at the Midwest semi-finals with four maxes and an 'almost.'
Construction is not unusual, so I will discuss features and fine points.
You should decide first on the weight class you wish to build, for. It is possible to cut down to 15 ounces for AMA rules on the 15 engine. But you will have to reduce wood sizes in the wing. Also choose lighter wood throughout. Best deal is the 20 ounce all-purpose model with ballast box. A shorter nose is indicated if you wish to fly only 19 8s 23 engines.
Lindy's wing is high aspect ratio (8-1/2 to 1) for a gas job. Has a 10% flat bottomed, low drag airfoil for good climb. It is a turbulent flow section based on a theory by Jim Lang. Allows the ship to ride. up and over gusts, instead of stalling out.
That 24% stab proves again that you don't need a big tail to control climb or glide. Our 20 inch 'stickoff' gear never fails, and allows ROG from any field. The flexible wire skid absorbs shocks from DT landings.
The center fin was originally a sliding fin to allow changes in amount and position of lateral area. It works this way: Due to pressure from the rotating slip-stream more area on top gave left power turn. More down below gave right power ,turn. However, it vibrated out once in flight. The fin is now glued in and a small section of it dictates power-on flight.
Secret of control is the combination of three fins. Center rudder setting (in slipstream) guides first five seconds of flight path. By then speed is up, nose is up. Slight right rudder in tip fins becomes effective and alters a nearly straight up climb to an efficient right spiral. Result: the model flies up on the wing, rolls out on top with no dip.
Note that the right wing has an aileron cut in the trailing edge near the tip break. This is a method of positive control for amount of wash-in. Never deflect this more than 3/4 inch.
Center of gravity is at 65% to control overpowering by hot engines. You can fly with three different engine sizes at one contest with but a ten minute change-over time for each. Arrange a bolt on lead weight to balance out the heavier 19 is 23. There is room inside the fuselage under the stab..."
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