UPTater

OK - everything but the control "rods" are installed. She weighs in at 2.8 lb. That's including a 3" diameter plastic nose-wheel. Should taxi pretty good in short grass. I won't get to finish her till next week. We're traveling for the 4th. I'll post more when I can...

Constrictor

My Feedback: (46)

Here is a PBF that i saw someone field make with another crashed airplane

SirKnight

My Feedback: (6)

I've built several PBFs out of coro and had a ball with them. But lately I've been flying foamies and my PBF was just sitting in the corner started looking at it. In a few minutes I grabbed a peice of 6mm Depon foam and started wacking on it. This is what I ended up with.

24" sq. PBF I used a 4mm CF tubing on the leading edge and one at the hing line CA and clear vinyl tape. Used 3/8" sq. spruce for the center spar CA to the foam and motor mount. Vert stab was CA to the foam and then I drilled a 4mm hole to threw the top of the foam in to the 3/8" spar CA and taped the 1/8" CF tubing to the front leaing edge of the rudder. I doubled out the nose peice. It came out weighing 14 OZ. with the 1200 mil battery. Used a Mini AC215/16 Brushless motor geared 6.60 to 1, swinging a APC 12x6 prop. motor is off set 2 degrees for thrust. 3ea HS-55 servos, .070 CF rods thin CA to nylon clevises stiffer than 4-40 metal rods. Took the cover of of my 7ch RX weighed less than a half of an OZ!

It flies just like my 40 powered PBF but better much easyer to hover and you can fly it OOOOHHHHH so slow it just floats when you power back!

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SirKnight

My Feedback: (6)

OPS the pics didn't work that way

Here's the pics of foamie PBF

Gordo-ProBro

That looks real nice.....but you gotta admit that is one expensive PBF!!!! Let's see some video

SirKnight

My Feedback: (6)

Didn't cost that much. The PBF cost me $10.87 total with carbon. I make a lot of foamies for the guys here and I buy the full sheet foam by the case (20 sheets) which comes to 6.00 bucks a sheet incuding shipping the same with the CF. I use only 1 motor and gear box for all my foamies I take several out to the field at a time. Takes less time for me to change the motor and controler, than refueling and starting a gaser. Was buying 1 battery each month for $36.00 now I'm up to 6 battery packs that I take to the field. Now I can be in the air all day long with a few TX battery and Li-poly charges.

UPTater

Tried to maiden her the other day. I almost got her trimmed out, but on my last attempt she curved around too close to the spectator fence & I though it best to wait till I can get out on a less populated day. BUT - I'm still not thrilled with her taxi-ability. I didn't make any tail-skids, but all she would do is turn & tip over, so far. Will tail skids help straighten out her taxi - or is this typical & I'll have to really compensate with the rudder. BTW - I went with a plastic nosewheel & aluminum "leg". I'll drop the gear if I have to, but I wanted to play with it.
Anybody got video of a good taxi in grass & pavement?

Goinstraightup

My Feedback: (26)

WOW-OOPS PBF's with tail skids taxi pretty good. I did notice that if you turn really sharp they will nose over some. If you keep from turning too sharp, the ground handling is really quite good with the skids.

Jeff

UPTater

She flew tonight


No too crazy about the taxi skills[>:] But - I still don't have tail skids. I'll try that before I drop the gear. She weighs 2.7lb & will climb out of a hover, but not with ghusto - if you know what I mean. Also - I started with my expo set to -60% & -40% on high & low rates, but didn't like the mushy center. So I bumped it 10% a flight until I settled at -30% & -10%. That "feels" better to me. She's balanced at 5" right now - a hover is almost automatic. After I get the hang of this, I'll move back to 6" & see the difference. Thanks Y'all for all the good advice - keep it coming.
I'd better sit with the wife a while before bed. She's been feeling a little neglected - since I discovered PBF's & SPADs.

UPTater

WOW-OOPS...

I got the PIC you sent - tell me more about the fuse.
Is that yellow coro & is there anything else in there for stiffening?
I like the looks of my wiffle ball bat - but I had to cut a foam saddle for it - kind of a pain.

Goinstraightup

My Feedback: (26)

Tater,

Nice Job!!! I am using less and less expo as well. I am using about the same as you. I like about 5 1/2" to 5 3/4" for my CG location.

WOW-OOPS PBF is almost identical to mine in post #1294 (top of this page), except he has the nosewheel and tailskids and he used plywood for the motor mount and I used Glass Nylon sheet. He has no leading edge stiffening and his spine is the fiberglass rods just like mine (I used his idea).

One area my PBF differs from yours and WOW-OOPS is my backplate on my engines are almost touching my LE like in Daves designs. By having your engines sticking out about an inch this gives you room for the nosewheel. I don't know if this affects flying much as WOW-OOPS PBF is very stable. I even think it makes the plane more stable. The only thing I can see is that with the engine sticking out further ahead, then you have to have all your radio components near the back to get a rearward CG. This is probably a good thing too as they are farther away from the ground when the PBF contacts it.

WOW-OOPS said that he told you about our fun fly. We'll both be there with our planes. I'm sending you my information and directions to our field.

Jeff

UPTater

From front to tail - OS-25 -> motor mount -> firewall -> battery -> 4oz tank -> mini receiver -> standard servos.
I had to stick the nose out there to get the C/G right.
If I drop the nosewheel, I'll be tailheavy in a hurry.
This is a neat design, but I think the next will be closer to yours' - with the CF rods.

Ain't this a cool hobby?

BTW - We're out of town this weekend, so don't look for me at the fun-fly.

Goinstraightup

My Feedback: (26)

No problem on the Fun Fly. Maybe another time. I'd like to see yours fly to get a first hand comparison of the designs.

The nice thing about the Bat is the durability and light weight. Looks like it mounts servos quite well too.

Jeff

UPTater

I'd like to try one without the foam saddle & see how it flies as the coro follows the bat's taper.
Maybe the foam saddle was work I could've avoided - a little less weight too.
I got too many ideas & not near enough time...

UPTater

Quick question...
Has anybody tried pull-pulls on the ail-evato-ron-flappy things?
It would seem to be the thing to do - everything could be mounted around the C/G, with less weight & no worries about rods bending.
I'm reading-up on the pull-pulls & am bound to try it.

BTW - I dropped the nose-wheel on mine... much better performance

SirKnight

My Feedback: (6)

UPTater try using .070 solid carbon rods they don't bend like the metal rods plus they are a bunch lighter. All I do is thin CA some Great Planes standard nylon clevises on the ends (after I center out the servos) You cant pull them off if you tried! Tried to pull them off with vice grips only thing I did was pull apart the nylon clevis, but glue joint never failed. I've used some CA debonder to take one end loose to make adjustments. I've even use them on larger planes too. The .070 CF rod is even stiffer than a metal 4-40 rod! Did a little test with them both at 12" placed weight in the middle the 4-40 bent (kinked) at 8.5 pounds the .070 CF rod finally failed at 18 pounds (broke)! My test system was holding the rods with my fingers with a plastic bucket handle located in the center and had a friend slowly add sand to the bucket till the rods failed and then weighed the bucket. Very scientific LOL

UPTater

That - actually - is how we were tested & graded on our truss projects in college.
Spanned them between 2 tables & hung a bucket of rocks from them.

I picked up some Golden Rods from the LHS the other day, but I like the simple ides the best.
Those are the ones I can wrap my mind around.
I'll look at those rods - thanks.

Dave McDonald

My Feedback: (19)

On the original P.B.F., I seriously thought about using pull-pull elevons. But what stopped me was the elevon horn hanging down below the plane.....which might break, damage, or disconnect the pull-pull linkage each time the bottom elevon horn touched the ground.

So I ended up using pushrods made from balsa cause they were light, cheap, stiff, cheap, easy to make, and cheap.

The rudder got a pull-pull using upholstery thread cause it was light, cheap, easy to setup, cheap, damage resistant, and cheap.

IMHO, carbon pushrods would be the ultimate pushrod for a P.B.F. They're very light, very strong, and very stiff. The only drawback would be the high co$t of a carbon pushrod.

SirKnight

My Feedback: (6)

The .070 X 48" CF rod only cost me $2.80 cheaper than Golden Rod. You can make enough push rods for three PBFs, because their so light you can move the servos back a little more making the push rods a little shorter. I've built several PBFs before using this setup. I found after flying them for a while they seemed to get a built in bow which makes it a little harder to fly inverted.
I found that sliding a 4mm CF tube in the first slot on the leading edge and one just before the hinge line it keeps it flat. Now they fly just as good inverted as up right.

This spring I bought 8 ea. 4' x 8' sheets of coro of different colors and built 64 PBFs for local guys. I have 6 left to sell . I have 2 setup with LA .40s on mine, but their looking a little rough now was going to setup another, till I built the electric foamie PBF to me it fly's sooooooooo much better hovers and harriers are a dream. It'll do the toilet bowl and a flat spin great, but it wont go into that wicked inverted spin [&o] It'll pull out of hover like a rocket and fly just about as fast as the ones with an LA .40

The foamie PBF will take pretty hard whop without breaking, be there and done that LOL! Plus I get 20 min plus fights and if I whop it in the ground I just throw it in the air again no starting an engine.

I love flying both kinds of them and that's what it's all about

UPTater

Well, I used the golden rods - since I already had them. That really helped stiffen up the control. I'd like to have a little better "down" - she still gets a little mushy flying inverted. But I did harrier & hover around pretty good today. I even did a tail touch on the safety fence - followed by a definative dorking. I had a blast! But I can see the avantage of PBFing electric. I got tired of walking back and forth to my field box. Next time - if nobody cares - I'll take my field box to the flight line with me. All-in-all I'd say this design is done. I won't change anything else until I have a reason to re-build...

Thanks Dave!

Dave McDonald

My Feedback: (19)

UPTater,
Glad to hear you got your P-B-F dialed in and you're having fun!

UPTater

Well, I’ve been a bad boy. Last night I was flying my PBF at our club field. There were only 4 people there (3 pilots). I was hovering around a little too close for their comfort. And I was given a friendly reminder that all flying is supposed to be on the far side of the runway. Just like that - I broke our safety rules – without even thinking about it. I apologized to everybody & from now on I will fly on the far side unless I’m all-alone. The flight characteristics of these PBFs – & their small size – will trick you into doing the same thing I did – if you don’t watch it. I hope this will be a reminder to you, before you do the same. We all need to be aware of others’ perception of these plastic planes & make an effort to avoid any “bad press”. I’m the only one at my field flying SPADs & the last thing I want is a new club safety rule prohibiting them. So I’m gonna be a good boy from now on – I promise.
BTW – posting this message is my penance.

Crazy-Ace 316

Flew my PBF for the first time today (I had put this project on the back burner for a while). Man, what a blast to fly!! I built it per Dave's plans and used standard Futaba 3004 servos, Dubro 6 oz fuel tank, and my Magnum XL .36. I was worried that it was going to be nose heavy because of the large engine and tank but it flew fine. My only problem was the Magnum. It didn't want to keep running. Every time I punched the throttle from low to wide open, it would quit. There were a lot of bubbles in the fuel tubing so I believe that that was the problem.

I flew it 3 times, and to my surprise, it flew almost like a normal airplane! It was going fairly flat and fast but once I get a lower-pitched prop it'll fly like it was meant too. The third time I took it up, the engine died (again) and it was about 30-50 feet in the air. I tried to flare it the best I could (it glides like a brick) but it crashed pretty hard and broke the left elevon's push-rod. Out of the 3 landings/crashes I didn't break a single prop!

I have a long shopping list for this plane now:

[ul][*]Change the push-rods to a harder wood[*]Change from a 6 oz to a 4 oz tank[*]Change from the 9x6 prop to a 9x4 or 10x4[*]Switch from zip-ties holding down the tank to rubber-bands[*]Put foam under the tank instead of the Styrofoam there now[*]Find some carbon-fiber tubes to stiffen the wing[*]And try to find some lightweight landing gear for it

[/ul]

I still can't believe this thing flies!?!

Goinstraightup

My Feedback: (26)

Nice job Crazy-Ace.

The PBF is alive and well in WI. Had 3 PBF flyers in one spot on Monday - UpTater, WOW-OOPS, and myself. Had tons of fun and even tried a little combat. Tater won the combat, but we all had a blast.

UPTater

BTW - The second PIC in the previous post is my current PBF - notice the streamer around my prop. Goinstraightup never had a chance -LOL. I'll admit it was a lucky cut - but for the sake of this post... I took that boy to school!

Seriously - I had a blast flying with WOW-OOPS & Goinstraightup! We're gonna have to do it again before the snow flies. I even got to fly & doink WOW-OOPS's Spa3d. I knocked the VERT clean off!. Afterwards he told me the VERT had already pulled out the screw holes - so I didn't really break it. That stinker set me up!