I would know it was pink inside...white will work...just need to find some and get into a sewing mood...that doesn't happen often.
Lowrider LSA
- Thread starter Lowrider
- Start date
I would know it was pink inside...white will work...just need to find some and get into a sewing mood...that doesn't happen often.
The Federal Aviation Administration's annual Aerospace Forecast predicts a gradual increase in general aviation hours flown overall, but piston-single aircraft are expected to decline about 0.8% annually in fleet size and hours flown over the next two decades.
Hope they are wrong. That's 16% in 20 years. Probably aren't any more accurate than the weather guessers.
A question...I only have about 3/16" clearance between the front inside corner of my fuel tank and the fuel tank access panel at the top of the front spar. I have adjusted the tank down as far as I can without it hitting the skin stiffeners on the bottom. If I had only made the front of the tank a 1/4" shorter. Does anyone see a problem with that hitting the spar and rubbing? The tank is PDT (pretty damn tight).
Hope they are wrong. That's 16% in 20 years. Probably aren't any more accurate than the weather guessers.
A question...I only have about 3/16" clearance between the front inside corner of my fuel tank and the fuel tank access panel at the top of the front spar. I have adjusted the tank down as far as I can without it hitting the skin stiffeners on the bottom. If I had only made the front of the tank a 1/4" shorter. Does anyone see a problem with that hitting the spar and rubbing? The tank is PDT (pretty damn tight).
skywagon8a
MEMBER
SE Mass MA6
If the tank is PDT it is unlikely to chafe on the spar. To alleviate any doubt you could insert a piece of felt or other anti chafe materiel for piece of mind. 3/16" is a lot.
Half inch would make me happy. I can put some rubber stuff I got for the straps all along the spar edge...that will make me comfortable but short of happy. I'm thinking immobile is better than large clearance gaps, but both are better I think. Hopefully, the next wing will have greater clearance although the tanks are very much the same size as are the spars...we'll see.
Has anyone fooled around with an arduino?? It's a programable micro processor that is set up to accept 12 inputs and 12 outputs. Apparently they are being used in race cars to program electronic fuel injection and electronic ignition. They are the heart of small robots and drones and #2 son is building controllers with them for several different things such as a traffic light controller and antenna tuner. He seems to think they will easily run an autopilot system with XYZ (3 axis) inputs from a GPS and outputs to servos. Not sure how fast the GPS signals refresh so there needs to be a few lines of code to keep the system from doing corrections too quickly or slowly as the case may be.
Best part...they cost ~$20 and have a micro USB port to plug into your computer to program them. Can't program...me neither...last time I could program was when Univac was making computers with vacuum tubes...fortunately #3 son does some serious programming so maybe I can co-opt him. Probably worth a few hundred bucks to see if it will work.
Best part...they cost ~$20 and have a micro USB port to plug into your computer to program them. Can't program...me neither...last time I could program was when Univac was making computers with vacuum tubes...fortunately #3 son does some serious programming so maybe I can co-opt him. Probably worth a few hundred bucks to see if it will work.
skywagon8a
MEMBER
SE Mass MA6
Eddie, I think that I've seen some of them around the edges of some of the airports in Florida. In Texas too.
The arduino has been used in some open-source autopilot projects, but 3DR has moved on to the pixhawk and gluon to the xbee. It is no lark to program an autopilot from scratch, there are 3 nested loops of 3 different types of feedback on each axis just for starters. Fortunately, if you're willing to fork out a few hundred, 3DR can sell you a pixhawk mini ready to go.
WOW! That sure gets my little brain smoking!! I'd be willing to try that but with more powerful servos...I think. If they are built for scale models they might come up short on being able to control a full sized, albeit small plane. As long as I can flip a switch or pull a breaker and shut it down I might be willing to play with it.
Thanks Skywalker...got my hardware guy looking at it as I type.
skywagon8a
MEMBER
SE Mass MA6
Low, Skywalker has a point. All his servos move are trim tabs on each control surface. Not the surface itself. The tabs wouldn't require a powerful servo since there would not be a high load on each tab. AND should there be a hard over failure you ought to be able to still fly the plane with extra muscle power. Uncomfortable maybe but not catastrophic.
I used to fly a DC-9. Are you aware that when you move the ailerons and elevator with the yoke that you are only moving trim tabs on the surfaces? The surfaces themselves are free floating. Not connected to any control except in the case of a full nose down on the elevator for stall prevention when some hydraulics kick in.
Sky,
I'm aware. I fly by trim tabs a lot. I welded in tabs for servos on the stick for ailerons and in the tail for the elevator and I suppose I keep thinking I need to be using them but I don't. Is having a tab on one aileron enough?
I spent some time last night looking at the Pixhawk 2.1 which is coming out soon. Apparently it is a quantum leap ahead in sensitivity and it can even use 2 GPS inputs which it will average for better control. If I can believe the hype it's pretty much a self-contained autopilot...just add servos. There are many controllers that can do the job so the real challenge is to find "actuators" that will handle control of a full sized airplane surfaces. There are plenty out there.
I'm aware. I fly by trim tabs a lot. I welded in tabs for servos on the stick for ailerons and in the tail for the elevator and I suppose I keep thinking I need to be using them but I don't. Is having a tab on one aileron enough?
I spent some time last night looking at the Pixhawk 2.1 which is coming out soon. Apparently it is a quantum leap ahead in sensitivity and it can even use 2 GPS inputs which it will average for better control. If I can believe the hype it's pretty much a self-contained autopilot...just add servos. There are many controllers that can do the job so the real challenge is to find "actuators" that will handle control of a full sized airplane surfaces. There are plenty out there.
Low, it's easy to spend $$ on RC servos, but it mostly goes to more precise gears for less backlash, digital feedforward servo amps and such for competition. You can buy big huge servos for less than $100 cuz they're simple and old design. They easily control trim tabs and they can be ganged together if you're not sure. You can buy curve matchers for ganging up servos without having them fight. You could gang up and it would still be a fraction of the cost of a real servo. Giant scale RC suppliers have many cool toys to get your brain going.
Skywalker,
Thanks for your thoughts and ideas!!
Precision in a cub size and speed plane does not seem critical. Reliability and no need for frequent maintenance tops my list. Any preferred brands?
I'm down to only 55 nut plates to go on the fuel tank cover...they should make zippers for stuff like that. Maybe the next wing willget a hinge on the front.
Thanks for your thoughts and ideas!!
Precision in a cub size and speed plane does not seem critical. Reliability and no need for frequent maintenance tops my list. Any preferred brands?
I'm down to only 55 nut plates to go on the fuel tank cover...they should make zippers for stuff like that. Maybe the next wing willget a hinge on the front.
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skywagon8a
MEMBER
SE Mass MA6
Low,
I would go for one tab on one aileron. It is only a trim tab operated by a servo. The servo should be durable and capable of continuous duty. Sensitivity could be adjusted by varying the size of the tab. An autopilot is to ease the pilot's work load and hopefully to make the ride smoother on a turbulent day. I've flown a pneumatic servo autopilot. It was very sluggish and behind the airplane all of the time. Probably not much better or worse than no autopilot at all. I would want one which was very sensitive. Enough to keep up with the turbulence which you are trying to combat.
Is this what you are talking about? http://www.proficnc.com/
I would go for one tab on one aileron. It is only a trim tab operated by a servo. The servo should be durable and capable of continuous duty. Sensitivity could be adjusted by varying the size of the tab. An autopilot is to ease the pilot's work load and hopefully to make the ride smoother on a turbulent day. I've flown a pneumatic servo autopilot. It was very sluggish and behind the airplane all of the time. Probably not much better or worse than no autopilot at all. I would want one which was very sensitive. Enough to keep up with the turbulence which you are trying to combat.
Is this what you are talking about? http://www.proficnc.com/
skywagon8a
MEMBER
SE Mass MA6
I would think that is more than enough.
The Hobby King brand "Orange" has an AS3X ripoff gyro for $20. Keeping heading hold drift in mind you could use it to hold straight and level for a few minutes while folding maps and such. It has sensitivities on all 3 axis on tiny potentiometers, couldn't be simpler./
As far as servos go, buy a good old Futaba "1/4 scale servo" for well under 50 bucks. Hook it up to an RC system and grab onto the output arm, which is usually 1.5 inches or so, with your thumb and forefinger. See if you can resist the motion while moving the stick on the transmitter. You will be impressed. I haven't shopped lately, but compare torque ratings and just go for greatest torque for the buck. I don't think resolution or speed even figure in this application. I'll bet it'll be hard to spend more than $200 on three entirely adequate servos.
As far as servos go, buy a good old Futaba "1/4 scale servo" for well under 50 bucks. Hook it up to an RC system and grab onto the output arm, which is usually 1.5 inches or so, with your thumb and forefinger. See if you can resist the motion while moving the stick on the transmitter. You will be impressed. I haven't shopped lately, but compare torque ratings and just go for greatest torque for the buck. I don't think resolution or speed even figure in this application. I'll bet it'll be hard to spend more than $200 on three entirely adequate servos.
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This looks like a good addition to the servo
https://www.servocity.com/637120
You were right Skywalker...these servos are damn powerful! Now if I can just figure out how to control them.
https://www.servocity.com/637120
You were right Skywalker...these servos are damn powerful! Now if I can just figure out how to control them.
Beaverpilot
Registered User
Manitoba Canada
I would be leery of hobby king gyros. They have a tendency to die when you don't want them too. I quit using them when they started destroying my RC helicopters before I could. As far as servos go JR, futaba and hitec are bulletproof. You can get most of them with metal gears in a coreless digital version. (Fast and precise) Additionally you should be able to power the gyro as a standalone system by bypassing the signal input wire input. The only issue I see so far is when the system self calibrates. They like to be in a level flight attitude with minimal vibration.
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I chose a Hitech HS-755HB Servo to use as an experimental to see if the Pixhawk 2.1 will operate it properly. I'm also using the exoskeleton to beef up the servo and take the lateral stress off the servo shaft since it will be taking any buffeting or turbulence against the tab. Good choice?
Beaverpilot
Registered User
Manitoba Canada
Looks good to me I have used those karbonite gears on some of my large scale birds. FYI. even most "metal" gear servos have one sacrificial plastic gear-keeps one from destroying the rest of the servo.
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Beaverpilot
Registered User
Manitoba Canada
It should work.
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There are voltage converters made for electric RC planes that have big Lipo stacks for the motors and you want to tap in for 5 or 6 volts for the guidance. I'm using one on a gasser, just so I can save weight by using a tiny 3s Lipo for guidance power. To address Beaverpilots concern, you can buy bypass boxes that send power directly to the servo, so you're not feeding main servo power thru some tiny gyro or autopilot circuit board. 18ga. would be better for the servo power. If you're going with digital servos(unneeded in my opinion) you'll get some big current spikes, and the voltage at the servo may sag. Since digital servos have some intelligence out there I wonder if voltage dropouts affect them more than an old analog servo.
The servo bearing block is a new one, told you you'd find treasure! 1/3 scale seems to be the biggest commonly available category, but some 1/2 scale cubs and bipes have flown. It's not too hard to put a feedback potentiometer on a power window motor and amplify the output of a servo amp to suit the motor. But I've lost track, bet you can just buy some whopper servos these days. Some of the birds you see at big meets makes me wonder why these guys didn't take their $20k and build something you can sit in. 100cc engines are becoming commonplace at RC fields, I used a 100cc Yamaha gokart motor to haul my entire self off the ground in a Quicksilver, 1981.
The servo bearing block is a new one, told you you'd find treasure! 1/3 scale seems to be the biggest commonly available category, but some 1/2 scale cubs and bipes have flown. It's not too hard to put a feedback potentiometer on a power window motor and amplify the output of a servo amp to suit the motor. But I've lost track, bet you can just buy some whopper servos these days. Some of the birds you see at big meets makes me wonder why these guys didn't take their $20k and build something you can sit in. 100cc engines are becoming commonplace at RC fields, I used a 100cc Yamaha gokart motor to haul my entire self off the ground in a Quicksilver, 1981.
Beaverpilot
Registered User
Manitoba Canada
Ha ha, I have often wondered what my total dollars spent were in the rc hobby. Over the last 30 years. I have thinned down my inventory quite a bit but I still have a 33% extra with a 100cc. I still love flying control line. And I see that my $1000 radio can now be had via a clone for around $75. I've been telling myself a dollar spent in rc is a dollar not spent on the cub.
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