Just a little skp design that I made during school, when I had extra time. no code yet as the school computers don't have phlat script, and 8 is giving me troubles. Designed for a Blue Wonder motor. Off of RCTF's Hydro Thing.

Attached files ATPCMBT.skp (31.8 KB)Â

 

I planned on cutting 4 skids, and bending depron around them, like the skykart wheels, although if it goes on h2o, I need to add a step to the skids. :mrgreen:

 

LeadFeathers PBF is very similar and uses wires bent into a curve for landing skids. I think the files are posted somewhere here on the forum. You might look into doing something like that for your landing gear.

As to the soda bottles.... What a cool idea! I never would have thought to do that! I am going to have to try that out.

Amazing what you can learn here.

 

All of these are great ideas. I have been using cut off zip ties for a long, long time to protect the bottom edges of gearless foamies and they work great. The soda bottles are an idea I HAVE to try. While I am at it, I could use some suggestions. I have cut out numerous versions of hydros, pizza flyers, etc. None of them have performed well. I know, because of their design, they can be tricky to fly but every one I build had the tendency to torque to the right when power is applied and this renders the machine unflyable. Maybe somebody can tell me what I am doing wrong. Too much motor? Too much prop? Dumb thumbs? Just for the record, my last attemp, only days ago, at flying a HOOT was to land it 65 feet high in a poplar tree. The wind blew it down yesterday (after ten attempts to shoot it down with a .22) but I have yet to find the battery. Is this a great hobby, or what?

Chuck
...somewhere in Indiana...

 

Dear Chuck,

Welcome to the club. Flying a device (notice, I did not call it a plane) such as this is a bit tricky.

I am on my second PBF after having flown them for about 2 years now. It is my all time favorite, but it makes one keep on their toes every millisecond.

The plane is quite unstable unless flown in high alpha at about a 60 degree angle.

Throttle management is key to being able to fly it. It is probably the single most important input you can give to the receiver.

Rudder control would be second on my list of needed elements to manage this type of device although many people do not know their radio has a left stick. I guess most of us are right handed and doing anything with the left hand is considered out of the question, but if you want to learn to fly well, you need to take your left hand out of your pocket and use it to control your aircraft.

Aileron and Elevator serve to keep the platform upright and are great for cool spins, loops, and aerodynamic wonders.

I personally like a good sized prop, squared off a bit on the tips. I want torque, not speed, so I choose a low pitched prop like an 11x4.7 and I think keeping the weight down as much as possible produces a better flying craft. I use a LazerToyz 17g CD rom motor and a 500 mah 3 cell lipo. The motor runs a bit hot, but I have never burned it out and I push it pretty hard.

Be careful in high wind! I once had one of these get away from me and it nearly landed in a lake before I gave up and dumped it. There was no way I was going to be able to fight the wind back to me. I love flying this thing low to the ground (where wind is less of a problem) and I like doing tail touches with it.

Once you have mastered flying one of these things, you will appreciate it. I find it a very good device for keeping my flying skills up, simply because you have to use all of the resources on your radio to fly it effectively.

Keep practicing! The best part is that if you do tear one up, a new one is only a few cuts away!

 

All good advice and taken to heart. Thank you! One more question...would making a pizza box flyer with only rudder and elevator be easier to fly stable than with elevons? I know the elevons allow tight fast rolls, but I also wonder if they contribute to the tendency to torque over. I have a left thumb, I should probably use it more!

Chuck

 

Good question. I don't think I would want to try it with only rudder and elevator though. I make use all of the inputs. These guys are just unstable as all getout and you are constantly needing to correct for one thing or another. A gust of wind can flip it on its side and you need to be able to react to that. With rudder only, you would probably end up crunching some foam.

Once you get the hang of it, this plane will make you a whole lot better pilot in the long run. I always start my day by flying my PBF. It loosens my fingers up and prepares my mind for the day. If for any reason, I am having problems flying the PBF that day, I don't take up my good planes. It could just be my concentration is not what it should be that day, or maybe the wind is just strong or whatever.

Speaking of fingers... I noticed you said you had a left thumb.... If you are flying with only your thumbs, you have another bad habit you need to break. You should be flying with your thumb and forefinger both on the stick. This gives you much better control and feedback to your brain as to exactly where the sticks are at any given moment.

 

Flash...breaking the thumb habit is going to be tough. I see some (some) pilots who fly with their thumb and forefinger. It looks awkward to me. I have tried it. The little depressions on the ends of the sticks are for thumbs (I think) and the sticks roll nicely on the ball of the thumb. This has to boil down to a matter of personal preference. It would be great to know the percentage of those who go one way or the other. I am not too old to learn if there is a concensus that it is better. I know designs vary, but is there a general rule for the CG location on a flat PB? I have decided CG is a critical factor in these these performing well, so that would be some handy information. I'm gonna try the thumb and forefinger thing, thanks for the advice.
Chuck
...somewhere in Indiana...

 

Hi Chuck,

Yes, the thumb habit seems awkward to break when you have not learned the proper technique from the getgo.

I too had to unlearn my bad habits. I watched the guys who flew very well and noticed none of them flew with their thumbs only. I decided there must be something to that and bought some books on the subject, did some research and decided to give it a shot.

Now, I am very glad I did. It is kinda like learning to wear seat belts in your car. Once you get in the habit, it just doesn't feel right going back to the old ways.

But don't take my word for it, watch some of the better pilots in your area and visit http://www.rcflightschool.com/ for some free lessons which will tell you the same thing.

I'm certainly not an expert flyer by any means, but my flying skills improved dramatically after switching to this method.

As to rule of thumb for CG on a PBF, I would say it the same for that of a wing chord, 25 to 30 percent of the wing which in this case is the entire flat area. And yes, it is critical. I have my battery mounted as far forward as it will go. My PBF is a little different than this one as it is an 18" square plate, but the general rule should apply.

For these planes to fly well, they need to be a little tail heavy. You want them to fly hands off at high alpha with about a 60 degree angle.

 

Gotcha! Thanks. I glued some 2L soda bottles on the bottom (they added a considerable amount of weight and the thing is pretty nose heavy). It looks like I will need to put the battery back a ways. I did scoot it on the garage floor (no rudder control yet) just to see how the little motor would pull it. No problem with power but again, wants to torque to the right really bad and I suspect this will be a problem if and when it ever leaves the ground. I am using a blue wonder and I tested it with a 8.4 prop. We will see after everything is hooked up.

Thanks buddy...

Chuck
...somewhere in Indiana...

 

An 8.4 prop and you have torque issues? Wow! I run an 11x4.7 on mine. I have about 5 degrees right thrust and down thrust built in.

I'm not sure I would ever try putting floats of any kind on a PBF. I wonder what they will do to the flying characteristics of this type craft.

Have you checked your lateral CG? Maybe you have too much weight on one side?

I can't wait to see some pictures of your craft.... and Video! You gotta get some video of this.

 

Here is the original video that I got the idea from.

~ Nate

 

Too funny! Very Cool! Hot Air Balloons, Ducks, and all! Now I gotta build one! I just never imagined being able to fly one of these off water!

Thanks for sharing!

 

No problem. I enjoy making the models. I'm sory that I have not quite yet figured out the Phlat Script yet. That doesn't stop me from posting models!

Here is a revision of it with a step on the floats. I have never flown off of water before, but this is just a guestimation on where the step is.

~Nate Attached files ATPCMBTstep.skp (28.7 KB)Â

 

Flashsolutions: Sorry for the late reply to your post. My PBF with 2 L soda bottles was pretty much a flop. It had (I stress "had") the tendency to nose-over. It would scoot pretty fast on asphault, but not on turf. I tried moving the bottle and cg everywhere, but no go. The PBF met its fate when I tried to hand toss it, it went straight down. So...no photos or no videos. It is back to the drawing board on this one. I am thinking I should have left some soda in the bottles, that way it could slosh back and forth and contribute to some pretty neat stunt flying. Overall, I think it was just too heavy, those empty soda bottles are heavier than you might think. I should have put a air fitting on the caps and filled them with helium.

IT IS THANKSGIVING DAY SO HAPPY THANKSGIVING TO YOU ALL!

Chuck
...somewhere in Indiana...

 

My findings exactly! I tried 4 variations of floats and all of them nosed over. Even tried moving the motor back 4 inches, but pretty much same result.

The video that was posted earlier shows one of these taking off and landing on water and it looks like it was just thrown together with chewing gum and bailing wire so to speak, but the dang thing works!

I don't have sketchup 8 installed, so I could not see what the floats looked like that rcflyboynj posted. Maybe his will have better luck.

 

My Bad. Here is a jpeg photo. Attached files