Retract Float Airplane
11-22-2006, 04:43 PM
#1
Retract Float Airplane
I started this thread under the subject called "Canard on Floats" because we were looking at several experimental ideas to play with, one of which was to take on of our canards and make a seaplane out of it. You mmight ask, "Why?" Well, we like to do things that very few or no other people have done. We get a lot of enjoyment out of trying new ideas and flying different planes.
My original post was requesting information and gathering data on the subjectsfor future use. No one answered with much info on any of the ideas so we settled on trying a plane with a single, center float that retracted. We knew the first test article would be pretty much of a mess since we had no experience in this area. There were bound to be areas we'd have to re-make or fix from the original design so we decided that we wouldn't worry about the first one being pretty or elegant, just functional. Later, when we had all the bugs worked out, we could design a plane where the retract float design fit into the design of the whole airplane.
I had an old Heckler, 3D plane with a GMS .47 in it, so the Sea Heckler with retractable float was about to be born. Flaps also had a float that would more than likely work for the center float. I ordered the Robart air-up, spring-down retracts and we were off and running.
Construction is done with minor adjustments taking place. Aparently, the length of the gear legs is critical and even a small amount will cause the float to leave a gap, a large gap when retracted. We are working on that. We could test fly easily, but neither of us wants to go up to the lake and get wet when it's 40 degrees, so we'll mark time for a good weekend here on the north gulf coats of Florida.
We are still open to ideas. I'm pretty sure it will fly as is, if it gets off the water. The big gap between the fuselage and the float isn't going to make any difference. We'll worry about covering that up on the next design. If you have any ideas for this or the next design that might helps or things we should avoid, please let me know.
Photo1 shows Flaps in his shop with the Sea Heckler. The tipo floats are some old ones we had. They are mounted on ply so a hard skid will break the strut and not the wing. Wings on 3D planes are pretty light and I thought that it would be easier to replace a strut than rebuild a wing.
Photos 2 & 3 show the float in the down position. One of the guys thought we might get wobble and poor tracking on thewater from the single wire main struts not holding the main float steady. This is not the case. The legs are 3/16 wire and seem to be a lot sturdier that we anticipated. We went as far as designing some side braces if we needed them, but it looks like they won't be necessary.
Photos 4, 5 & 6 show the float retracted. You see what I mean when I say it doesn't come up all the way. We knew it wouldn't be flush because of the way we mounted the rails on the outside, bottom of the fuselage. There just isn't any extra room in the Heckler fuselage. I think the main trouble area is that the nose of the float hangs down. Flaps is going to check and cut-and-try, but he thinks the front leg is very slightly longer than the rear one. At lease this is what the geometry seems to indicate. As I said, we're working on it, but it has taken longer than we expected.
For our final design, I think the fuselage and main float should be the same width with skirts or the fuselage sides exdtending down to mate with the top of the float, hiding all the working mechanism inside.
We also plan to retract the tip floats. Another set of Robarts out there woulkd weigh a ton so we figure on going with mechanicals. Think about the geometry of mechanicalk retracts. The pushrod comes from the center of the plane and the gear retracts inward. Reverse this so the tip float retracts out toward the tip and I need the retract servo mounted out by the actual wing tip. I was looking to find some old Goldberg retracts since they retract from either direction, but they don't seem to be made any more. Does anyone know of a set of retracts that work from either side?
Another problem, when the tip float is down, unless the wing is long, the float is going to be at nearly half span unless I make the struts fairly short. Does anyone have experience with tip floats mounted several inches inward from the tips and any problems that occurred?
My original post was requesting information and gathering data on the subjectsfor future use. No one answered with much info on any of the ideas so we settled on trying a plane with a single, center float that retracted. We knew the first test article would be pretty much of a mess since we had no experience in this area. There were bound to be areas we'd have to re-make or fix from the original design so we decided that we wouldn't worry about the first one being pretty or elegant, just functional. Later, when we had all the bugs worked out, we could design a plane where the retract float design fit into the design of the whole airplane.
I had an old Heckler, 3D plane with a GMS .47 in it, so the Sea Heckler with retractable float was about to be born. Flaps also had a float that would more than likely work for the center float. I ordered the Robart air-up, spring-down retracts and we were off and running.
Construction is done with minor adjustments taking place. Aparently, the length of the gear legs is critical and even a small amount will cause the float to leave a gap, a large gap when retracted. We are working on that. We could test fly easily, but neither of us wants to go up to the lake and get wet when it's 40 degrees, so we'll mark time for a good weekend here on the north gulf coats of Florida.
We are still open to ideas. I'm pretty sure it will fly as is, if it gets off the water. The big gap between the fuselage and the float isn't going to make any difference. We'll worry about covering that up on the next design. If you have any ideas for this or the next design that might helps or things we should avoid, please let me know.
Photo1 shows Flaps in his shop with the Sea Heckler. The tipo floats are some old ones we had. They are mounted on ply so a hard skid will break the strut and not the wing. Wings on 3D planes are pretty light and I thought that it would be easier to replace a strut than rebuild a wing.
Photos 2 & 3 show the float in the down position. One of the guys thought we might get wobble and poor tracking on thewater from the single wire main struts not holding the main float steady. This is not the case. The legs are 3/16 wire and seem to be a lot sturdier that we anticipated. We went as far as designing some side braces if we needed them, but it looks like they won't be necessary.
Photos 4, 5 & 6 show the float retracted. You see what I mean when I say it doesn't come up all the way. We knew it wouldn't be flush because of the way we mounted the rails on the outside, bottom of the fuselage. There just isn't any extra room in the Heckler fuselage. I think the main trouble area is that the nose of the float hangs down. Flaps is going to check and cut-and-try, but he thinks the front leg is very slightly longer than the rear one. At lease this is what the geometry seems to indicate. As I said, we're working on it, but it has taken longer than we expected.
For our final design, I think the fuselage and main float should be the same width with skirts or the fuselage sides exdtending down to mate with the top of the float, hiding all the working mechanism inside.
We also plan to retract the tip floats. Another set of Robarts out there woulkd weigh a ton so we figure on going with mechanicals. Think about the geometry of mechanicalk retracts. The pushrod comes from the center of the plane and the gear retracts inward. Reverse this so the tip float retracts out toward the tip and I need the retract servo mounted out by the actual wing tip. I was looking to find some old Goldberg retracts since they retract from either direction, but they don't seem to be made any more. Does anyone know of a set of retracts that work from either side?
Another problem, when the tip float is down, unless the wing is long, the float is going to be at nearly half span unless I make the struts fairly short. Does anyone have experience with tip floats mounted several inches inward from the tips and any problems that occurred?
11-22-2006, 05:02 PM
#2
RE: Retract Float Airplane
Ed, I have a set of no-name mechanical retracts that I plan to operate with a pull-pull cable. You could put the retract a strut-length in from the wingtip, and only use one, centrally located, retract servo. Just run a pull-pull cable out and around a metal pin or pulley in the wingtip for the "pulls-out" direction.
Pushrods get in the way of properly actuating mechanical retracts anyway.
Oh, and lots of tip floats are not mounted all the way out to the tip. As long as they have the bouyancy to keep from being submerged, they are fine-maybe even less prone to hooking ans spinning the plane around.
Pushrods get in the way of properly actuating mechanical retracts anyway.
Oh, and lots of tip floats are not mounted all the way out to the tip. As long as they have the bouyancy to keep from being submerged, they are fine-maybe even less prone to hooking ans spinning the plane around.
11-22-2006, 05:57 PM
#3
RE: Retract Float Airplane
I wish everybody would stop using anything but a pull - pull control setup for everything.
It take dozens of turns easily. Has no slop. Reverses easily.
Use Monofilament fish line and overtravel is automaticaly done.
Push pull everything.
It take dozens of turns easily. Has no slop. Reverses easily.
Use Monofilament fish line and overtravel is automaticaly done.
Push pull everything.
11-22-2006, 09:29 PM
#4
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RE: Retract Float Airplane
Ed... A couple of things come to mind:
How far does the cg move backwards when the float retracts?? My prediction would be that the reduction of drag below the cg and the rearward movement of the float as it retracts would both lead to a significant nose up pitch. (I have an internet degree in armchair engineering.....
)
I'm not sure how sturdy that float will be on those pogo stick struts as there is nothing to withstandlateral twisting...maybe something like a DC-3 or Mosquito main strut would be stronger.........
How far does the cg move backwards when the float retracts?? My prediction would be that the reduction of drag below the cg and the rearward movement of the float as it retracts would both lead to a significant nose up pitch. (I have an internet degree in armchair engineering.....
)I'm not sure how sturdy that float will be on those pogo stick struts as there is nothing to withstandlateral twisting...maybe something like a DC-3 or Mosquito main strut would be stronger.........
11-23-2006, 10:40 AM
#6
RE: Retract Float Airplane
Wayne,
The only thing I could find on the CG shift was an old, 1975, article from the defunct, RC Sportsman magazine on a plane with a retract float. He used electric actuators for the retract mechanism, by the way. He mentioned to balance the plane with the float retracted, that is, in the most rearward location. This we have done. The author indicated you took off and landed with a slightly forward CG, but the changes you noticed in flight were small. You would probably have to hold some up elevator on take off and on final. At any rate, the only thing to do is test fly to see for sure.
Now that I think about it, I may have the solution in hand. There is a setting on my JR 9303 radio that allows different trim settings for different flight modes. When I first read about it, I thought, "Who wants it?" Of course I was thinking of rates and mixing for flight modes. Now that this comes up, I am thinking I could use this feature. With the float down, lots of drag down low and the CG forward, this would require a lot of up trim. On the test flight I would trim the plane for this mode. After I retract the float, I would have to re-trim for the next flight mode, but I'd have to re-trim anyway due to the CG and drag change. When I put the float down for landing, the trim would go back to what I had set for that flight mode.
I'm glad this came up. I just learned how I can use one of the obscure functions on my radio. I'm sure that are lots of functions on these computer radios that most of us don't use.
Float strut stiffness. A couple of guys at my field mentioned this to us when they saw the proposed design. I really got worried about this so we designed a trapeze on either side of the strut we could add on to stiffen it up. After feeling the stiffness of the float, we don't think it will be a problem. The struts are short stubs, less than 6 inches, of 3/16 wire without a loop. They have virtually no flex. The float is stiffer than nearly all of my flxed floats. There is basically no give at all in the gear-strut-float assembly. I am now thinking I should have bought the gear with the Robo struts so the thing wouldn't be so solid.
The only thing I could find on the CG shift was an old, 1975, article from the defunct, RC Sportsman magazine on a plane with a retract float. He used electric actuators for the retract mechanism, by the way. He mentioned to balance the plane with the float retracted, that is, in the most rearward location. This we have done. The author indicated you took off and landed with a slightly forward CG, but the changes you noticed in flight were small. You would probably have to hold some up elevator on take off and on final. At any rate, the only thing to do is test fly to see for sure.
Now that I think about it, I may have the solution in hand. There is a setting on my JR 9303 radio that allows different trim settings for different flight modes. When I first read about it, I thought, "Who wants it?" Of course I was thinking of rates and mixing for flight modes. Now that this comes up, I am thinking I could use this feature. With the float down, lots of drag down low and the CG forward, this would require a lot of up trim. On the test flight I would trim the plane for this mode. After I retract the float, I would have to re-trim for the next flight mode, but I'd have to re-trim anyway due to the CG and drag change. When I put the float down for landing, the trim would go back to what I had set for that flight mode.
I'm glad this came up. I just learned how I can use one of the obscure functions on my radio. I'm sure that are lots of functions on these computer radios that most of us don't use.
Float strut stiffness. A couple of guys at my field mentioned this to us when they saw the proposed design. I really got worried about this so we designed a trapeze on either side of the strut we could add on to stiffen it up. After feeling the stiffness of the float, we don't think it will be a problem. The struts are short stubs, less than 6 inches, of 3/16 wire without a loop. They have virtually no flex. The float is stiffer than nearly all of my flxed floats. There is basically no give at all in the gear-strut-float assembly. I am now thinking I should have bought the gear with the Robo struts so the thing wouldn't be so solid.
11-23-2006, 12:23 PM
#7
RE: Retract Float Airplane
Ed, I mentioned a Watts linkage in the previous thread. It assures linear motion.
Here's a sketch of how it could be applied, but there is a lot of room for fitting it to a specific airframe.
I drew the link in 3 positions to show how it deflects as the float goes up and down.
Same thing guides the rear axle of a Nascar stocker
This would be to locate your float fore/aft. Your retracts would still be there to force the float up and down. I am envisioning the retracts coupled to a slider fixed to the top of the float so the retract rod could slide forward as it extends, but the float only goes vertically, guided by the watts link. (invented, oddly enough, by James Watt to guide the piston in his steam engine)
Here's a sketch of how it could be applied, but there is a lot of room for fitting it to a specific airframe.
I drew the link in 3 positions to show how it deflects as the float goes up and down.
Same thing guides the rear axle of a Nascar stocker
This would be to locate your float fore/aft. Your retracts would still be there to force the float up and down. I am envisioning the retracts coupled to a slider fixed to the top of the float so the retract rod could slide forward as it extends, but the float only goes vertically, guided by the watts link. (invented, oddly enough, by James Watt to guide the piston in his steam engine)
11-23-2006, 01:15 PM
#8
RE: Retract Float Airplane
Old mind on drugs gets things scrambled.
Cables. Pull- pull.
Just took out the flex cables to the rear surfaces of the 6' China clipper. Short nose of her means, I really gained a weight reduction on the battery location, almost coming out of the nose.
Now it will be under the cockpit.
Cables. Pull- pull.
Just took out the flex cables to the rear surfaces of the 6' China clipper. Short nose of her means, I really gained a weight reduction on the battery location, almost coming out of the nose.
Now it will be under the cockpit.
11-24-2006, 12:19 AM
#9
My Feedback: (32)
RE: Retract Float Airplane
Great project, Ed
I started on the same thing a few years back and kinda got held up a the counter balancing part of mine.I've made a gear drive to move a counter weight to counter the cog from the float movement.I have it all done up in the ruff form but just havent moved it to the plane yet.Too many other thing keep popping up.But I'll get it finished one day.As long as I don't start a new project.
This is my thread on RCCanada
http://www.rccanada.ca/bb/viewtopic.php?t=5880
Since the pictures were took I made the rear part of the float bigger,I switched to robart 605 mechanical with a single air cylinder in the middle with shafts out both ends to active the retracts at the same time.mine were binding a little with the two separate air cylinders,and working on the counter balance system.I used the small .40 size robarts for the wing tip floats ,works great.rods to the middle of the wing to a modified servo horn ,with a 3/8 air cylinder moving both tip floats.And two air control valves .All works flawless.I made a gear box that will move a 5oz weight around 24 inches.A cable comes off the back retract connects to a gear slide travels the one inch retract stroke and the gear box moves the weight on a rod supported at both ends. Now too just get the balancing system fined tuned and as small and light as can be . then mount on the underside of the plane.
I still might have to change a few things but hey this is what the hobby is all about.
I can't wait to hear how your test flights turned out,May help me when my planes ready.
Joe
I started on the same thing a few years back and kinda got held up a the counter balancing part of mine.I've made a gear drive to move a counter weight to counter the cog from the float movement.I have it all done up in the ruff form but just havent moved it to the plane yet.Too many other thing keep popping up.But I'll get it finished one day.As long as I don't start a new project.
This is my thread on RCCanada
http://www.rccanada.ca/bb/viewtopic.php?t=5880
Since the pictures were took I made the rear part of the float bigger,I switched to robart 605 mechanical with a single air cylinder in the middle with shafts out both ends to active the retracts at the same time.mine were binding a little with the two separate air cylinders,and working on the counter balance system.I used the small .40 size robarts for the wing tip floats ,works great.rods to the middle of the wing to a modified servo horn ,with a 3/8 air cylinder moving both tip floats.And two air control valves .All works flawless.I made a gear box that will move a 5oz weight around 24 inches.A cable comes off the back retract connects to a gear slide travels the one inch retract stroke and the gear box moves the weight on a rod supported at both ends. Now too just get the balancing system fined tuned and as small and light as can be . then mount on the underside of the plane.
I still might have to change a few things but hey this is what the hobby is all about.
I can't wait to hear how your test flights turned out,May help me when my planes ready.
Joe
11-24-2006, 01:26 PM
#11
RE: Retract Float Airplane
Joe,
It was the photos of your plane that got us thinking about it. Nice looking plane, a lot more refined than ours.
Does your fuselage have side skirts to hide the retract machanism on top when it is retracted?
The CG change, something you are using the counter weight for, is one of the things we want to test out before we get into a really nice airplane.
It was the photos of your plane that got us thinking about it. Nice looking plane, a lot more refined than ours.
Does your fuselage have side skirts to hide the retract machanism on top when it is retracted?
The CG change, something you are using the counter weight for, is one of the things we want to test out before we get into a really nice airplane.
11-24-2006, 07:44 PM
#12
RE: Retract Float Airplane
Mike B/Minnflyer:
I don't know what else to tell you about a watts linkage. Google it and you will get a jillion links with photos that are probably better than my pictures. Or make one with construction paper if that's what it takes.
I've been thinking about Ed's plane, and a couple of slider pins going straight up and down would do the same job and be lighter. Only you'd have a couple of pins sticking out of the top of the fuselage when the float is retracted.
Of course the whole vertically retarcting float thing is totally unnecessary if Ed's plane's CG stays within the limits. As it is now, the CG goes forward for slow flight and goes aft for the flight mode where maneuverability counts. At least the direction is right as long as the CG does not move too far. I once built a very nose-heavy plane and it did not have enough elevator authority to land easily......
I don't know what else to tell you about a watts linkage. Google it and you will get a jillion links with photos that are probably better than my pictures. Or make one with construction paper if that's what it takes.
I've been thinking about Ed's plane, and a couple of slider pins going straight up and down would do the same job and be lighter. Only you'd have a couple of pins sticking out of the top of the fuselage when the float is retracted.
Of course the whole vertically retarcting float thing is totally unnecessary if Ed's plane's CG stays within the limits. As it is now, the CG goes forward for slow flight and goes aft for the flight mode where maneuverability counts. At least the direction is right as long as the CG does not move too far. I once built a very nose-heavy plane and it did not have enough elevator authority to land easily......
11-25-2006, 12:45 AM
#13
My Feedback: (32)
RE: Retract Float Airplane
Thanks for the kind words Ed,I wanted to build a goldburg extra so I got some plans form a fellow flyer and cut it out I made extra tops and sides .The bottom of the plane was just raised to the tank floor level and went from there.The retracked float does sit in the fuse a bit.there enough room between the top of the float and the bottom of the plane to have the counter balance move.The retracts are inside the plane .
The gear box will sit at the COG inside the plane with a shaft sticking out the bottom and atatched to that is a sail boat winch pully.The line will run from the winch pully throug some sliding door rollers to the counter weight and pull it along the rod.
The plane is about 12-13 lbs with a 120 2-stroke for power .It should fly but know super aerobatics.Just a concept I thought I'd like to try.
If I were to do it again,I would use either a mid wing 4 star 40 or a lanier stinger,lots of space in the belly of the plane.I might have to build a new wing anyway with a little more area,but I will try this one using flaperon mix on my radio,Should help with lift on take off.I see the plane everyday in my hooby room and say I'll finish you one day ,but with my wife and I buying a house a few years old ,my time has went in to doing the reno's and when I'm burnt out from that it seems the wife wants more time ,And late at night you can only get litte RC things done when work calls the next day.
I'll try and get some photos for you of the inside and the balancing unit lay out.I'm just not the greatest when it come to the computer thing.I only seem to use it to surf the internet.
Any idea when your going to test your Plane?
Joe
The gear box will sit at the COG inside the plane with a shaft sticking out the bottom and atatched to that is a sail boat winch pully.The line will run from the winch pully throug some sliding door rollers to the counter weight and pull it along the rod.
The plane is about 12-13 lbs with a 120 2-stroke for power .It should fly but know super aerobatics.Just a concept I thought I'd like to try.
If I were to do it again,I would use either a mid wing 4 star 40 or a lanier stinger,lots of space in the belly of the plane.I might have to build a new wing anyway with a little more area,but I will try this one using flaperon mix on my radio,Should help with lift on take off.I see the plane everyday in my hooby room and say I'll finish you one day ,but with my wife and I buying a house a few years old ,my time has went in to doing the reno's and when I'm burnt out from that it seems the wife wants more time ,And late at night you can only get litte RC things done when work calls the next day.
I'll try and get some photos for you of the inside and the balancing unit lay out.I'm just not the greatest when it come to the computer thing.I only seem to use it to surf the internet.
Any idea when your going to test your Plane?
Joe
11-29-2006, 05:19 PM
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RE: Retract Float Airplane
Doh[:@] now I've spotted this..see your Canard thread I will transfer it here later see the Blackburn B20.............Ive been thinking screwdriven operation a quick flick operation wouldn't be right and I'm thinking of electric flight.
11-30-2006, 06:14 AM
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RE: Retract Float Airplane
Sorry its been months since Ive been able to visit this site Im still adjusting
A Blackburn prototype challenge for a scale expert builder? Take a look how they did ...information is short on this Aircraft as there were only two built both reportedly handled well on the water and in the air..excluding the presumed fatal Aeleron problem.....remember its less than 50 years from the Wright Brothers for most flyingboat evolution.
Some great historic stuff Blackburn Short etc and use the Green buttons to access the other pages..proposal to Convert BN Islander to flying-boat version
http://kheeley.tripod.com/sw.htm
More stuff on the Blackburn B20 flying-boat on dingers aviation pages
http://freespace.virgin.net/john.dell/blackburn_b20.htm
Three view here and more info on a one off
http://cloud.prohosting.com/hud607/.../b20/index.html
http://en.wikipedia.org/wiki/Blackburn_Aircraft_Limited
Someone has to have a crack at this if just for the site of the hull being deployed please let me know if you do. Ive done some Paint scribbling of ideas and have some useful modified imagesto work out the proportions of the linkagesand how to actuate the center float.
Ive got a resource thread set up at http://www.rcgroups.com/forums/showt...80#post4800471 amongst others.
A Blackburn prototype challenge for a scale expert builder? Take a look how they did ...information is short on this Aircraft as there were only two built both reportedly handled well on the water and in the air..excluding the presumed fatal Aeleron problem.....remember its less than 50 years from the Wright Brothers for most flyingboat evolution.
Some great historic stuff Blackburn Short etc and use the Green buttons to access the other pages..proposal to Convert BN Islander to flying-boat version
http://kheeley.tripod.com/sw.htm
More stuff on the Blackburn B20 flying-boat on dingers aviation pages
http://freespace.virgin.net/john.dell/blackburn_b20.htm
Three view here and more info on a one off
http://cloud.prohosting.com/hud607/.../b20/index.html
http://en.wikipedia.org/wiki/Blackburn_Aircraft_Limited
Someone has to have a crack at this if just for the site of the hull being deployed please let me know if you do. Ive done some Paint scribbling of ideas and have some useful modified imagesto work out the proportions of the linkagesand how to actuate the center float.
Ive got a resource thread set up at http://www.rcgroups.com/forums/showt...80#post4800471 amongst others.
