lotech

Hello,

I'm lotech(more ways than one) You can find I think everything about your engines @mecoa.com
also parts and manuals.Good luck,

Lotech

lotech

Hey guys,I'm new and I hope you will help. Is there anyway to take the warp out of coro?
Anyone can view my 1st post on topic here. Like I said it's been a long road to find PBF,
I hope I can fit in and get help.
TNX'S
Lotech

RC MANIAC119

My Feedback: (14)

Both are quality engines.........but I wouldn't use either of them on a PBF, they're too good! Find yourself a nice lite profile to stick them on!

Dave McDonald

My Feedback: (19)

Garrett, the HP 40 used to be a popular engine with the fun fly crowd due to it's light weight and good power. But IMHO the HP 40 is still too heavy for a PBF. The Irvine 40 is pretty much a standard run-of-the-mill 40 size engine. Works fine.....but doesn't really stand out at anything.

lotech, how bad is your coro warped? If it's not bad, and it's going on a PBF, I wouldn't worry much about it. If it's a severe warp, then you might try a heat gun while twisting it in the opposite direction. Just be careful not to melt the coroplast with the heat gun.

jdkxtreme

Well guys I just maidened my pbf..I never thought I would be able to take a sheet of coro and make it fly..I used everything out of a crashed tango..Besides the motor..I ended up having to use the bigger fuel tank because that is all I had.. I used an os .40..I did not try anything besides making circles but it did fly..thanks guys for all the post..

Ariba

Hello Dave,

You've been on this forum for a long time by now. Didn't expect to see any replies of you after I saw the starting date of the thread.
Like to thank you for posting the information and your website.

I build my first PBF about 5-6 years ago. together with a friend. He had a OS .25 engine and lighter electronics. I only had a Webra .40 and 15 year old electronics. So to reduce weight I tried a 3mm version reinforced with carbon rods first. It didn't fly well. And I had only just learned to fly my second plane. So I wasn't realy up to the job myself.
Next version with lower wingload. 36"x25" 4mm and slightly bigger ailerons. We still laugh about that one. If it took up to much speed. It did the hippie shake. The entire coroplast plate got into a sinus wave. It made the thing very unpredictable. Carbon reinforcing rods did not help.

The friend I mentioned still has his PBF. He has flown it a lot in the first year. Not so much after that. It got bend in a hot car. A carbon rod helpt to make it straight again. He cut the front corners a bit because the were to crumbled. It has eaten a lot of propellors by now, but it still flies.

2.5-3 years ago I've cut back the 36"version to 24"x24". Put on a balsa spine and a coroplast box. Took a 200-250 Watt brushless motor. 3s 2100 mAh lipo cells and started flying it again. After 10 10x5" propellors and 5 motor axles I have started with a folding prop 10x4". That helps a bit. mostly only one blade at a time. 5-6 blades a year. 1 axle a year. Lately I discovered that 11x4" is even better if I don't push the motor too long.
It isn't as quick and powerfull as the glowengine, but response is much more quick and reliable. It is less intimidating if you hover it around youreself, and it can still get into an inverted spin.

The 5x5mm balsa steering rods have after 30 or so repairs been replaced by flexibel carbon once. They simply bend and flex back if you push them to hard in a crash not in normal flying.

The last 2.5 years it has been the only "plane" that always flew. I made about 40-50 flighthours with it. It must have crashed over a 100 times. And then I meen the inverted spins I couldn't get out of, 15-20 meters nosedives into the ground and stuff like that. Complete sideways flips and rols on the ground and other more than rough landings.

I started flying with a normal plane again 2 month ago and had a hard time. It didn't hang in a 45° angle in the air.

Latest change is some LED lights for nightflying. Not easy and i haven't been able to get it out of an inverted spin. (It never gets into a normal one.) In the dark. But you can still fly it slowly and even torque it if you could. I still can't.

I'll try to add a picture of a nightflight

Greetings,
Henri

Dave McDonald

My Feedback: (19)

Henri,
Glad to hear you and your friend have been having fun with your PBFs for many years!

The electric conversion sounds like it worked out good, and the night flying version looks great.

You mentioned several times about not being able to get out of an inverted spin. Both upright and inverted spin recovery techniques are explained in detail on my PBF website, but I'll post them again here to save you the trouble of looking them up.

INVERTED SPIN RECOVERY:
To exit from an Inverted Spin, neutralize the rudder and aileron, then apply full power and full DOWN elevator. The PBF will instantly exit the inverted spin enter an outside loop. After 1/2 loop, the PBF will be in level upright flight and you can fly out from there.

UPRIGHT SPIN RECOVERY:
To exit from an Upright Spin, neutralize the rudder and aileron, then apply full power and full UP elevator. The PBF will instantly exit the inverted spin enter an inside loop. After 1/2 loop, the PBF will be in level upright flight and you can fly out from there.

Note that the spin recovery techniques for a PBF require the opposite elevator input compared to a "normal" plane.

Thanks for taking the time to tell us about your PBF adventures!

Ariba

Hey Dave,

Thanks for the quick responce.

I actually learned how to recover al lot of the spins by your explanation. It just took me some time. And when I first electrified it the battery was farther forward and on top of the red box. Witch made the center of gravity so far up that it would get easily and instantly into an inverted spin and nearly impossible to get out. Later I moved the battery behind the box, on to the "fuselage" and farther to the back. Now the center of gravity is much better and it is much more flipstable. It doesn't flip so easily anymore while trying to torq and I give the right corrections I can get it out within a couple of spins and a few meters. It doesn't fly forward as stable anymore because of the CG farher back. But that's not what it's made for anyhow.

The next thing we want to test is if we can tow a small glider with it. For the first test I'm gone screw the landinggear back on I think.
I've tried it on a slope, but it doesn't fly well soaring It is where the idea of towing a glider came from do.

I've flown it up to 5-6 beaufort winds, it isn't really made for that either. You'll have a hard time if you're trying to torq being blown sideways with 15-20 miles an hour. It only ways about 27 oz.
It was at an electromeeting. I heard some Oh's and Ah's a couple of times being blown away and recovering 2 feet to an inch above the ground again.

Some other people gave it a try too, but the thing looked easier then it really was to them I think. Till now I'm the only one flying it at a regular basis at our place.

Wonder if there are anymore dutch people flying the pbf?

Greetings,
Henri

Ariba

By the way with my version after I pulled it out of the spin I must lower the rudders a bit from the 45° angel they have. Else it doesn't pick up speed anymore and I have a hard time getting fulll control back.
I must admit I still have to get more comfortable with getting in a spin after so many times when there was no way to get it out and costing me 7 euro's for a propellor and a motor axle every third time it did that. I mostly try to avoid it. Or give full rudder and slam the throttle down if I'm not sure I'm able to get it out. That way the sound wenn hitting the ground is much better. But with the new propellor I can take a little more risk and it is getting better.

Henri

Garrett1234567

Hi all, its been a while sence ive been here, ive been flying flatout electrics for a while. My esc burnded up a few days ago so i threw together a new pbf. I forgot how much fun it was. I took it to a buddies house the other day to show him. We got a few flights in before the rain can and was having so much fun i just couldnt stop. I had all the ele. sealed in a bag. Heres a vid of it in the rain. http://www.youtube.com/watch?v=rPIIngZsb5g

ProBroJoe

Bump...

My version of a PBF.

Magnum Pro .25
Top Flite 10 x 3.5 nylon prop (a nice and flexible vintage prop)
4 ounce tank
2 Futaba S148 servos on Elevons
1 Futaba S3004 servo on pull-pull rudder
1 generic micro servo on throttle
Futaba R127DP PCM receiver
600 mAh NiCad battery, no switch harness.
2 lb. 9 oz.


Total cash outlay $0, that's right, $0. Put 'er together in about two lazy evenings from bits and pieces I had laying around. (The decals came from my Phoenix Models F20 propjet - didn't use 'em on the F20 and just couldn't throw 'em away!) All that's left to do is, well, fly it!

Goinstraightup

My Feedback: (26)

Very Nice BroJoe!!! Let us know how you like it.

Dave McDonald

My Feedback: (19)

Looks good!
Waiting for a flight report!

skola28

ProBroJoe, nice work on the PBF! Btw, that Top Flight Prop is the best I've ever found for pizza boxes. I've flown mine for about 8 years, and have wrecked it at LEAST 100 times... Still using the original Top Flight Flexible nylon prop!

ProBroJoe

Thanks for the compliments guys!

I actually got to fly the thing today - oh my gosh, what a hoot! The winds were kickin' up pretty good, but at least it wasn't raining like it has been since I finished it, so I ran out after work today and gave it go.

Being that I built my PBF with the aluminum U-channel spine (left over from other SPAD projects) it was real easy to launch. I just hold the spine with the right hand, throttle up to about half with the left, and simply push it away in a slight nose-high attitude - she just flies right away without any drama. (This is definitely one of those planes that you "fly on the wing" - the whole time!) There were several times when I got the thing into an unrecoverable snap-spin, and I don't know how I did it, but she went into the ground with a "plop". I just walked over, knocked the mud off of it, fired it up, and let 'er rip again - as a matter of fact, I had about six take-offs, but only one intentional "landing".

I'm sure some of the strange behavior I was experiencing was the wind, so I can't wait to get out there on a calmer day... gotta get comfortable enough with it to take off and land from a patio chair! [8D]


Anywho, here are a few pics of the "after" as well as details...

-Joe

Dave McDonald

My Feedback: (19)

Sounds like you had fun with your PBF, even in the wind. You'll like it even better in calm winds.

Upright and inverted spin recovery techniques are explained in detail on my PBF webpage.
http://mypage.yhti.net/~dmcdnld/pizzabox.htm

If you intend to wring out the PBF in inverted maneuvers, I'd suggest enlarging the fin/rudder to 8"x8" with a 4" rudder.

ProBroJoe

Thanks for the link Dave - I actually re-read your tips after I posted last night and realized that's exactly what was happening. There were a few times I recovered from the spins by instinctively fire-walling the throttle and pulling up... something musta stuck in my brain from skimming your pages earlier. That old Mag Pro .25 surprised me, definitely has plenty of power, even with that 10" prop on there, and throttle response and linearity is right up there with the .40 FP (I almost put on).

Fun stuff fer sure!

ProBroJoe

Flew the PBF for almost two hours after work yesterday. The winds were light and variable, so I got to enjoy the true PBF experience! When Dave says this thing will teach you to use all four controls, he isn't kidding. I spent the last three tanks (outta six) just flying around at eye level doing nose-high flat turns (of about 3 foot radius), dragging the tail through the grass, hovering, torque rolls, and general mayhem / stupidity. Ended up breaking the Top Flight nylon, but that's OK cause I had bought some MA 10 x 4 props and they're working out good. The PBF flies little faster compared to the 3 1/2" pitch TF, (duh) but the thin cross section of the MA allows the Mag .25 to rev a little quicker - which of course translates to better control. Anybody thinking of building and flying one needs to remember, slower IS better.

Fun stuff guys, and definitely fearless flying!

-Joe

Dave McDonald

My Feedback: (19)

Nice flight report! Glad to hear you were able to finally wring out the PBF in fairly calm winds. Sounds like you had a blast!

Goinstraightup

My Feedback: (26)

This thread needs a bump Just flew mine at our winter fly Saturday..

RC MANIAC119

My Feedback: (14)

I flew mine Saturday also......we let some local kids shoot paint balls at it!!!

Bundubasher

Hi Dave,
Where do you put the CG of the PBF?

Looks a very interesting flying Mcgadget.....

Cheers

Dave McDonald

My Feedback: (19)

Recommended CG range is shown on the plans.

Go with 5 1/2" if this is your first experience with a PBF. 6" is the ideal spot once you get used to flying it.

Goinstraightup

My Feedback: (26)

That's one way to add some color

hoelshot83

My Feedback: (1)

I am looking at building a pbf and want to make it electric. what would be a good cheap motor and esc to install?