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Oct 31, 2018, 03:34 PM
Registered User
8x6 woknt produce enough thrust on 2s. I switched tl a 10x4.5 much much better feels like it will hover about half throttle.

Ready for maiden just need tl tidy up cabling and all is go for a heavy indoor pizza box flier

Rough and not exactly flat. Not sure how to straighten it mother than remove the paper on bottom.
Last edited by bazsound; Oct 31, 2018 at 05:39 PM.
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Nov 01, 2018, 12:06 PM
Registered User
Tidied up the wiring today used heat shrink tubing (non shrinked) just to hold them beastly together.

As usually I've done thinks back words. Put everything on top instead of the bottom. Reciever is last although I do need to move it slightly as 1 side is heavier than other.

Didn't use wire for undercasrrisdge. Just foamboasrd pieced. Had tl make them larger due to 10" prop. Taxis great on my carpet. So rudder is defiantly working
Nov 04, 2018, 09:23 AM
Registered User
Didn't manage to get a maiden. Brought it to the field but upon powering up. Had throttle at full when I plugged bhatterry in.

I have a yep 17a speed controller and doing so messes up the programming. For some reason it turns on hell mode so now the motor spools up super slow.. Didn't have a programming card with me so that was that.

Wasn't happy with control throws so made new holes in the horns and it's looking much better.

Weighs in at 325g...

I could save 50g by changing the motor to a bluewolnder and switch out the 2s 850 for a 2s 370. I'd need to remove paper from the elevons though as withjoiut the heavy motor and battery it might end of being tail heavy
Nov 05, 2018, 01:46 PM
Registered User
Maiden was eventful. Really should have trusted myself I knew it would just want to fly up. After fighting with down trim running out and still not having enough I came in for a bumpy landing. It's not cg.

Adjusted control horns to pout a touch of down and things were much better it settled into the most surprising slow flight. Almost like a video of a 2s version I seen on YouTube indoors.

Flew it around hasrriered it and got it into a hover where it started to exhibit a very strange behaviour. Wing rock while vertical?????? Event I all it spun 180 putting me in an uncomfortable orientation so I let it down. Only damage was the very fuse detached itself.

Ready for indoor I think.

The wing is not straight due to having paper removed from line side so this probably accounts for some of the upness. But maybe a few degrees of down might help as it happens more with higher throttle strange as the engine is mounted inline with the wing
Nov 06, 2018, 06:19 AM
Watt Waster
Tsavah's Avatar
Good luck with a heavy PBF.
Latest blog entry: Center of Gravity - Airplanes
Nov 06, 2018, 11:00 AM
Registered User
Originally Posted by Tsavah
Good luck with a heavy PBF.
Pretty confident it will work well just need to not hit anything lol that bug 10" prop will eat up the flimsy small models. Seems that wing loading isn't as much of an issue with deltas and pizzbox flyers. Even though is heavier than originally designed there's still twice as much if not more swing area than a compasra ble sized foamie. I found the same with the qv3d I build recently (something between a quasar and Delta 3d) scasled to 38" despite weighing in at 1kg is a. Joy to fly and will fly nice and slow pasrticulslry in a barrier.

I may be mistaken but the stall is where you defiantly see it. It's not gentle or slow and requires quickly on the rudder and power as it drops to 1 side (guessing 1 wing heavy)

It's currently being painted will post pics
Nov 06, 2018, 07:22 PM
Registered User
Bottom paint job finished. Just needs the top done now

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Nov 06, 2018, 08:45 PM
Winging it >
leadfeather's Avatar
Baz, are those twin fins permanent? The fins mounted way up front like that (especially ahead of the cg) those fins will likely make the craft very yaw unstable.

Nice paint, good luck!
Nov 07, 2018, 06:04 AM
Registered User
Originally Posted by leadfeather
Baz, are those twin fins permanent? The fins mounted way up front like that (especially ahead of the cg) those fins will likely make the craft very yaw unstable.

Nice paint, good luck!
That's the underside they are the landing gear. Due to the 10" prop I had to make them slot taller other the prop hits the ground. Because I built it around 2s battery and a dst 1200kv motor 8x6 didnt produce enough thrust. Onlky 3s i hasd was 1000mah which was too heavy.

Ive flown it once and it actually seemed to fly oretty well in bank. I could hasrrier and also hover but as previously mentionef it startted to ing rock badly after hovering for a while
Nov 07, 2018, 05:55 PM
Registered User
So despite it's weight I was able to fly it around the smallish hall. To get it to fly slowly you really need tl get it into high alpha quickly andinto smooth turn. Once you loose keeping the wing level and start rocking speed shoots up fast.

I found myself in Yank and bank a couple times after running out of rudder.

Had to repair a few times. Taxis very well. Landing gear does not take well.

Think this will be a better outdoor flier although in better hands would fly this easily.

I have somefosm that came with the fridge it's a bit thicker almost 1cm but it's way lighter. It. May need some sort of spar but might suit an indoor pbf.
Last edited by bazsound; Nov 07, 2018 at 06:15 PM.
Nov 09, 2018, 05:08 PM
Registered User
PaulB's Avatar
Originally Posted by leadfeather
KarlP, Nice video! Very smooth controlled flying especially for a 10 year old, nicely done. I love the way these PbF's can float so slow and stable, almost like magic.

PaulB, Good luck with you little PbF. With such a little motor, keeping it light will be the key to success. Best of luck, please post your results.


'Doing' a 60 Cm EPPYAK55 for the up and coming indoor season (on the side of the ball that points up) I found a 5 Gram motor which I forgot that I had. Thinking what to do with it so I was looking on here on the scratch-built thread and the PBF has popped back up to the top and it reminded me that I built one which was still somewhere in the cellar, searching for the C of G position here and I see this post in reply to what I wrote above.

Sorry, didn't get around to replying 8 years ago ( ).

Didn't get on too well but mostly because I was over-propping the motor and trying to fly too fast, mostly outside. Put her to one side until I found cheap airbrushes on eBay and needed a nice 'canvas' to practice on around 3 - 4 years ago and put her to good use and then again last week.

First flights last night and I couldn't get the C of G far enough forwards and at first was flying with 2S. 3S with much larger throws got her flyable but I need to be able to adjust the C of G. Bit difficult as well because I was flying amongst Tiny Whoop racing in a small hall.

PBF (2 min 34 sec)


Nov 10, 2018, 06:54 AM
Registered User
I ended up putting my servos quotes far forward plus I was using a 50g motor but I out that down to the heavier foam board I used as that's always quoted ass an issue in some designs causing tail heavyness.

Think I ended up actually slightly nose heavy as I was able to move my battery as far back as the leads would allow.
Nov 13, 2018, 11:19 AM
Registered User
Decided to make another one. I've got these sheets of foam that I saved from when we got a new fridge freezer.

This stuff feels super light but it's also quite flexible. It's that annoying stuff that breaks up into little balls that sticks to everything. Unless you have the shasrpest of knifes the stuff makes a mess.

Anyway cutout 2 20"x20" squares. 50g! So after making the step then the main airframe I'm probably around 40g. Now just need canopy. So say I'm back up to 60g once the fuz is made.. 25g motor.. 3 5g servos that's 100g. Plus 25 for battery. Then esc and control rods horns
So say 150g..
Nov 13, 2018, 03:17 PM
flyin' fool
goldguy's Avatar
Here's a few of the dozens of PBF I've built over the years ......................

All successful fliers because they had a low wing loading and lots if thrust.
Nov 13, 2018, 04:06 PM
Registered User
Originally Posted by goldguy
Here's a few of the dozens of PBF I've built over the years ......................

All successful fliers because they had a low wing loading and lots if thrust.
Very nice. Our hall is quite small . I have a 3d fosmy but I find its still a bit too fast even in barrier and the stall isn't as mild was I'd like.

I'm gonna cover it in coloured packing tape maybe that will stiffen it up a bit

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