Free Flight Jet models.

[WIDDOG]

First Trim flights I have a long way to go but looks like maybe it will fly. http://youtu.be/FmP0iOZZfj4

[kittyfritters]

First Trim flights I have a long way to go but looks like maybe it will fly. http://youtu.be/FmP0iOZZfj4

You have some balls flying a stick and tissue model on a muddy field! That flight is not bad considering the size and weight. A little down thrust should cure that stalling tendency. If it works, then put in more winds.

How much rubber is in it? Did you give the wing any dihedral?

Now you've got me interested in doing a version of it, not that I don't have other things to do.

Howard

[WIDDOG]

Now you've got me interested in doing a version of it, not that I don't have other things to do.

Howard

That would be awesome to have you working on rubber powered Jets. unfortunately I am only a intermediate level model builder/flyer. The reason I posted this build was to try and get other model builders interested in FF Jets. Even if I can't get this prototype to fly I consider this a over all success.

The plane has a dihedral on the tail elevator an a Anhedral on the wings. IMHO the plane would not look right with a dihedral wing. I started trimming with one loop or two strands of 1/8 inch thick rubber. I now have loaded for the next tests one loop or two strands of 3/16 inch thick rubber, at about 1.5 length. I also will glue a 1/16 inch thick wedge in the thrust bearing, for down thrust.

[WIDDOG]

FAIL... I tried flying my model Jet again today. It failed miserably. I equate the pusher prop Jet as trying to push a chart with a rope. Pulling a chart with a rope works fine... Anyway another FAIL for me. Oh well back to the drawling board. Next on my Jet list to try is RDF (Rubber Powered Duct Fan)

[kittyfritters]

Now you've got me interested in doing a version of it, not that I don't have other things to do.

Howard

That would be awesome to have you working on rubber powered Jets. unfortunately I am only a intermediate level model builder/flyer. The reason I posted this build was to try and get other model builders interested in FF Jets. Even if I can't get this prototype to fly I consider this a over all success.

The plane has a dihedral on the tail elevator an a Anhedral on the wings. IMHO the plane would not look right with a dihedral wing. I started trimming with one loop or two strands of 1/8 inch thick rubber. I now have loaded for the next tests one loop or two strands of 3/16 inch thick rubber, at about 1.5 length. I also will glue a 1/16 inch thick wedge in the thrust bearing, for down thrust.

You are not flying in the speed range or with a wing as large as the real airplane is. Many of the rules of aerodynamics used to design full sized aircraft do not apply with wings of less than 5 inch chord and speeds of less than 25 miles per hour. Getting a model to fly sometimes requires some deviation from scale. Sharply swept wings require less dihedral than straight wings. I have made rubber powered deltas that required no dihedral at all and pusher flying wings that required minimal dihedral. A little too much dihedral in a wing (straight or swept) can cause Dutch Roll, a waddling through the air. Way too much dihedral, with a swept wing, can lead to roll-yaw coupling and require an increase in rudder area. Too much rudder area can lead to spiral instability. What to do? In the case of the A7 my initial approach would be to put the dihedral in the bottom surface of the wing. The ribs decrease in height toward the tips, so I would build the wing panels then raise the tips enough when joining them so that the upper surface of the wing is flat, when viewed from the front, but there will be noticeable dihedral on the bottom of the wing. This would be a good compromise between appearance and the necessities for flight. I would also leave the dihedral in the elevator, but increase the size of the elevator by 10 to 15 percent to give it more authority.

Let's see, the A7 at 1:16 scale would have a 29-1/16 inch wing span...Humm...

Howard

[davidchoate]

SEE? THERE'S SO MUCH MORE INTERESTING STUFF ABOUT FF THAN i EVER THOUGHT. i MEAN, NOT THAT THERE IS'NT IN RC, BUT WITH RC, HAVING CONTROL OF POWER AND CONTROL SURFACES, YOU SOMETIMES DONT HAVE TO BE AS CONCERNED ABOUT KEEPING EVERYTHING VERY PRECISE,AND PUTTING MODIFICATIONS,AND ALOT OF PLANNING PRIOR TO, DURING, AND AFTER YOUR BUILD. I HAVE ALOT OF OLD ISSUES OF M.A.N. MOSTLY FROM THE 80'S, AND I HAVE BEEN READING THE FF SECTIONS ALOT LATELY. THERE'S ALOT OF COOL STUFF. LIKE A RUBBER POWERED TORQUE ACTUATED RUDDER ETC. I WAS THINKING ABOUT MITCH WANTING TO MAKE A RUBBER POWERED DROPABLE BOMB, AND NOW SEE HOW POSSIBLE, AND SIMPLY THESE THINGS CAN BE DONE IF THE INFORMATION IS AVAILABLE.

[kittyfritters]

SEE? THERE'S SO MUCH MORE INTERESTING STUFF ABOUT FF THAN i EVER THOUGHT. i MEAN, NOT THAT THERE IS'NT IN RC, BUT WITH RC, HAVING CONTROL OF POWER AND CONTROL SURFACES, YOU SOMETIMES DONT HAVE TO BE AS CONCERNED ABOUT KEEPING EVERYTHING VERY PRECISE,AND PUTTING MODIFICATIONS,AND ALOT OF PLANNING PRIOR TO, DURING, AND AFTER YOUR BUILD. I HAVE ALOT OF OLD ISSUES OF M.A.N. MOSTLY FROM THE 80'S, AND I HAVE BEEN READING THE FF SECTIONS ALOT LATELY. THERE'S ALOT OF COOL STUFF. LIKE A RUBBER POWERED TORQUE ACTUATED RUDDER ETC. I WAS THINKING ABOUT MITCH WANTING TO MAKE A RUBBER POWERED DROPABLE BOMB, AND NOW SEE HOW POSSIBLE, AND SIMPLY THESE THINGS CAN BE DONE IF THE INFORMATION IS AVAILABLE.

David,

The first model I built with my father, back in 1948, was an Avenger that dropped it's torpedo when the rubber motor wound down. There where a whole host of kits by Joe Ott, Airline, and Sterling that dropped bombs, or drop tanks, or parachutes, or fired spring loaded rockets (Nothing projecting forward is permitted under current AMA safety rules.) when the motor wound down. The mechanism for this is quite simple, The motor attached to a pivot around the motor peg that is spring or rubber loaded so the it rotates as the motor goes slack and a linkage attached to it that trips a latch when the pivot has rotated to a certain point.

Now if you really want to think about it a little, using a combination of this, and early RC technology (rubber wound escapements as used before servos) you can build a rubber powered model with landing gear that retracts after ROG and extends for landing. I've drawn this up but haven't yet made the time to build it. Of course, with the micro-electronics available now it would probably be easier to make an electronically driven landing gear with some sort of proximity detector for the ground, but then it wouldn't be pure rubber power, would it?

The thing about RC is that the technology has advanced so far, with inexpensive receivers that have laser gyro chips in them, that virtually anything can be made to fly under control no matter how unsound it is aerodynamically. (Witness quad-copters.) There are a lot of RC models being flown that could not fly free flight and would simply fall from the sky if the receiver battery went dead. A free flight model is not just a toy, but a challenge since you have to understand the forces in play before you let it go. Once you let it go, it's on its own.

Howard

[kittyfritters]

Just like a child.

Oh! How true!

[davidchoate]

I AGREE. I RECENTLY GOT A 16"WS RC SPITFIRE FROM HOBBY ZONE. IT HAS A BUILT IN FLIGHT CONTRPL THAT WILL STABILIZE IT. THE WINGS ARE MABE FROM A HARD FOAM NO THICKER THAN A PAPER PLATE WITH ABSOLUTELY NO AIRFOIL. BUT, AS ADVACED, AND LIGHT AS THESE ELECTRONICS ARE, IT HAS BEEN MY EXPERIENCE THAT THEY ARE UNDERPOWERED, AND UNRELIABLE. I HAVE TAKEN SEVERAL 500 SERIES GUILLOWS, AND ADAPTED THESE MICRO BOARDS INTO THEM. IF YOUR LINKAGE/HINGES ARE NOT PERFECT; THEY WILL NOT MOVE, OR WORSE, THEY WILL BIND IN FLIGHT. THIS HAS HAPPENED TO ME.I WILL NOT CONVERT ANYMORE 500'S.BUT ON A 400 SERIES, THE SLIGHTLY LARGER 3-7g SERVOS, AND 5 CHANNEL LITTLE SPEKTRUM RECIEVERS WITH AN OUTRUNNER ARE JUST FINE. I HAD AN IDEA,STILL IN IT'S INFANCY, INSPIRED BY WIDDOGS TINY JET OF A RUBBER POWERED DUCT PROP. I MEAN ALOT OF GUYS ALREADY USE A BLAST TUBE. THATS HALF OF IT THERE. AND A 2 OR MRE SMALL COUNTER ROTATING FANS I THINK MIGHT HELP THAT "SPINNING ROLL" WIDDOG ENCOUNTERED. IF I EVER GET THE TIME I'M GONNA TRY IT.

[WIDDOG]

http://youtu.be/b-XSs4-Slmw

I like the way this person thinks.

[Brenda]

I finished the A 7 today. AUW (All Up Weight) 24.5 g. The decals are tissue copies of the Guillow's F 14 decals. First nice day I will take outside and hopefully fly her. I am going to send a picture to Guillow's who knows maybe they may have an interest in this model.

Gotta say wow. I use to work for LTV back in the day and worked on many of the A-7's before transferring to MLRS line. Always wanted to find a kit of one to build.

[WIDDOG]

Update

I started this post by wanting to fly the Guillow's F 14 Display only kit. I am now working with electric timers and micro EDF's (Electric Duct Fans) I am also still waiting and hoping for the return of Rapier motors.

I did try the Estes Mini Rocket Motors. They are kind of expensive at around $2.50 a shot. http://youtu.be/Mv3OCZFyMD4.

[davidchoate]

If you invent a good Electric FF timer, let me know. Are they controllable. Or just land like a Rocket with a Chute?

[WIDDOG]

I have both the Brushed and Brushless timers. They are "Great". They have two adjustable screw type pods. One pod controls throttle or rubber FF equivalent to thickness of rubber. The other pod controls length of power or the rubber FF equivalent to number of winds.

The owner of this website builds them himself. They, like a said above, are great. Very small and light weight. Every easy to adjust. The owner of the company is very knowable and will answer questions over the phone.

http://microflierradio.com/Timers.html

[BillParker]

...nipsy dazers, with or without the scooter stick...

..

Ha Ha! You only left out one!... Good work!


bp