FP 25 on a Bi-Slob - with a little Flying Flounder thrown in for fun. =-)

[Paul Taylor]

Would a FP 25 be a good engine for a Bi-Slob???

[Wynn Robins]

yes

They work well.  Ultimatley a dirty old fox 35 running REAL rich is the way to go

[Allan Perret]

I have a FP25 on mine and my buddy has a LA25 on his. 
They both work great on the Slob with 10-4 or 9-5 props.

[john e. holliday]

Should work great.  I have my FP .25 in the "Humbug" as the plans show Fox .35 Stunt and I know its got as much power or more than the Fox.  It used to be in my version of Walter Umlands' "Sweet Sweep".  With the only tank I could fit in the Sweep I only do one lap between maneuvers to get a fast pattern in.  Good luck,  DOC Holliday

[Tom Rounds]

I thought there was an unwritten law that a By-Slob had to have a Fox .35 for power!

[Jim Kraft]

And what made you think it was unwritten. It was written in the archives of Bislob many years ago. I think Fox Superfuel, and Fox plugs were also written in there. The prop used is still being argued to this day although a 10-6 is the right one. Some guys just like to be different.

[Clayton Berry]

Not legal. 

Fox .35 only.

You folks keep screwing around, and God will stop us all with one big-assed bolt of lightning.  Don't screw it up for the rest of us.  The CL world has enough problems without you clowns screwing up with Bi Slobs.  Fox .35 - only! 

Don't make me get out my axe.

[john e. holliday]

If Jim Lee was not at VSC or if I see him and he can get a computor he can straighten us all out on Bi-Slobs.  His says I am still flying on  too long of lines.  I fly on .015 X 60,  Fox .35 Stunt well broken in,  10% Nitro and 10 X 5 prop.  Remember the Fox is set just lean enough to get airborne as once you start doing things it will lean out until you level out again.  And as Jim pointed out to me after about three minutes you are ready to land if you play a lot.  DOC Holliday

[dave siegler]

The break is really nice to have on the slob, I can't make my FP's do it.  I don't know if I could slow an FP down enough.

Don't you have a Fox that came with the slob? 

[Andrew Hathaway]

If you use a standard vent tank, and your flying surface is smooth enough, you can set the needle on a Fox 35 so it's so sloppy rich that the Bi-Slob will just get off the ground, and fly but it doesn't take much to make it stall and settle back onto the ground.  Gotta be careful not to let it plop down on it's back, or let the gear get bent back too far. The first part of the tank is perfect for touch and goes with hovering, then towards the end when the rpms start to pick up, you can do more of the other maneuvers like loops, eights, etc.  Even if an OS could do it, it wouldn't be nearly as much of a "Slob".  A Bi-Slob really deserves a Fox 35, the same way that a OS 25FP deserves a real plane, like a Twister.  It'd be a waste to use a strong engine on a Bi-Slob.

[Alan Hahn]

I think a FP or LA 25 will be too clean.

The "Slob" part comes from the 1/4" layer of "caramelized" castor oil (~1.2 oz of the 4 oz tank) deposited all over the left side of the plane. You almost need to wipe it off before the next flight, 'less the weight increase alters the fine balance point of the Slob. 

"Bi-Clean" just doesn't sound right.

Also my Fox 35 never breaks into a 2 stroke at all--even at the top of the wingover.

[catdaddy]

Not legal. 

Fox .35 only.

You folks keep screwing around, and God will stop us all with one big-assed bolt of lightning.  Don't screw it up for the rest of us.  The CL world has enough problems without you clowns screwing up with Bi Slobs.  Fox .35 - only! 

Don't make me get out my axe.

Agreed! So it has been said and so it shall be written. If anything but a fox 35 is used on thou Bi-slob there will be great wailing and knashing of teeth!

Amen.

[Clayton Berry]

Hi, Rick.

[catdaddy]

Hi, Rick.

What up Clayton?
How's that little guy doing? You got him flying a slob yet?
Hope you and I get to drink a beer together at Brodak's this year.

[Fred DiMaria]

Hi  -

I have a Bi-Slob with a OS .25 FSR (R/C) with the throttle tethered. I have experimented with setting the throttle at half throttle to full throttle. I agree that I can't seem to get this motor to replicate the 2-4 break.  My Slob is the Brodak ARF version. Having a tough time getting it to hover like some of the on-line vids. 

Any suggestions, should I add tail weight, increase the engine offset, or dump the OS FSR for a Fox .35?  I am running a 9x6 zinger. The motor runs perfectly, which may be part of the problem?

[Paul Taylor]

I would say start but dumping the FSR and go with a known.

Fox 35 or FP 25

[Fred DiMaria]

I have never seen one fly with a 25FP - are they capable of the 2-4 break?

[Bill Little]

I have never seen one fly with a 25FP - are they capable of the 2-4 break?

Basically, no.

BIG Bear
RNMM/AMM

[Paul Taylor]

I have a FP25 on mine and my buddy has a LA25 on his. 
They both work great on the Slob with 10-4 or 9-5 props.

I think a few guys at Brodaks had OS engines on there. I fly mine on a Fox. But like Allen said he uses one and some guy even has a LA.25 on one. You don't need the break to hover them. If you wiggle the elevator when you stall it in a tight loop it will cause it to sink. And slip it in the wind.
Hope this helps.

[Fred DiMaria]

What about adding tail weight, I was going to experiment with that. Also, I think the built in factory offset may not be enough, the line tension is ok when flying in a circle, but gets slack when I do loops.

[Paul Taylor]

With the built in engine off set and the rudder off set I think there is enough. The plane should balance on the top spar.
The plane is very light on the lines when in hover mode.

It almost is flying by itself, you are just hanging on by a thread.

[Bill Little]

Sacrilege!  I tell ya it is appalling!  The Bi Slob gods will smite those non Fox .35 Bi Slob models!  Just too much horror to hear of such things as a .25LA on a Bi Slob....... oh the humanity!

BIG Bear
RNMM/AMM

[Paul Taylor]

Not on mine.

[Bill Little]

Not on mine.

Ah rootbeard, you are safe from the wrath!

BIG Bear
RNMM/AMM

[john e. holliday]

Any suggestions, should I add tail weight, increase the engine offset, or dump the OS FSR for a Fox .35?  I am running a 9x6 zinger. The motor runs perfectly, which may be part of the problem?

First thing is ditch the 9-6.   Go to a 10-4.   Run the engine just lean enough to get air borne.  Also use shorter than 60 foot lines.  I think mine are down to 56 foot by .015.   It also helps if you have a slight breeze for hanging down wind.   By the way if the 10-4 still pulls too much, you  may have to locate a 9-4.

[Allan Perret]

The Red trophy in this picture was won by me with my FP25 powered Slob at the Clanton, Al. contest last year. 
It was an un-official event just for BiSlobs.  I think the other 2 entrants were Fox35 powered.
What say all you na-sayers ?
 

[Paul Taylor]

Allen,
That is some nice hardware! I sure need to put this contest on my schedule next year.

Can you share with us the rules for the Slob event?

[Fred DiMaria]

I am going to try the 10-4 prop and adjust the balance, I just checked it and it appears to be nose heavy when I balance it on the top spar.  I will let everyone know if my slob becomes the SLOB he is meant to be!!!

[Paul Taylor]

As someone said shorter lines.
I fly on .015 55ft.

[Allan Perret]

Allen,
That is some nice hardware! I sure need to put this contest on my schedule next year.

Can you share with us the rules for the Slob event?

Clanton is a great contest.   On my Fall Contest list for sure.

BiSolb event was short on rules but long on fun.  The 3 slobbers had each flown solo.  At this point no one knew there was a Trophy involved.  It was suggested that the 3 of us go up together.  Based on what we had done in the warm up solos they asked me to fly the center high routine.  The other 2 flanked me right and left down lower.  My whole flight was between 45° and the top of circle with several extended periods between 75° & 85°.  I think thats what got me the surprise trophy after the official awards.

I think part of what lets me hover pretty much straight overhead is using the FP25 with .012"x57'or58' lines.   I dont bother trying to make it 4-2 break.  To set needle I point it staight up and set it so it just barely wants to climb out of my hands.  With that setting and a little breeze it will usually hover right around the 45° point.  

[Steve Thomas]

Here's another thought.  Forget the Bi-Slob and build a Flying Flounder instead.  Even better, use an RC throttle on your FP25, and have a third line.  You'll have something that's quicker and easier to build than a Slob, flies similar, and is just a heap of fun.  You can even do vertical takeoffs from a suitable launch rail.

Here's a bit of video of mine, powered by an RC FP20:

[Allan Perret]

Here's another thought.  Forget the Bi-Slob and build a Flying Flounder instead.  Even better, use an RC throttle on your FP25, and have a third line.  You'll have something that's quicker and easier to build than a Slob, flies similar, and is just a heap of fun.  You can even do vertical takeoffs from a suitable launch rail.

Here's a bit of video of mine, powered by an RC FP20:

Steve:  Nice job flying the Flounder.  What 3-line system you using on it ?  You seem to have better throttle control than the one plane I built with throttle using the J Roberts system.  That was a converted SIG Ultimate Fun Fly (Bipe) using both a LA-46 and a Saito 56.

I built this Flounder about 8 years ago around same time I built the BiSlob,  both using a FP-25.   Both are a boot in the butt to fly, but I have more fun with the Slob

On the Flounder I used some un-conventional materials and techniques in the building process.  Have lots of pictures if you want to see.

[Steve Thomas]

Hi Allan, I'm using the J Roberts system as well.  First time I've ever tried it, and to be honest I'm a bit amazed at how well it works.  Maybe I just got lucky, or perhaps the FP20 is particularly well suited to it. (Although as you probably know, the control throw from the bellcrank to the throttle is fairly high-geared, which makes fine control a bit tricky when trying to hold a stable hover, but otherwise it works just fine.)  I had a previous 2-line Flounder which was fun, but this one is a whole lot better.

I'd certainly be interested in more pictures of your Flounder.  I considered wheels as well, but ended up getting a bit fixated on the idea of a VTOL model.

Cheers
Steve

[Paul Taylor]

Steve, Allen,
Very cool stuff. I had never seen one of these fly before. I wonder rather then the throttle if you could get this plane to hover better with a Fox doing the break?

Again me just thinking out loud.

[Steve Thomas]

 I wonder rather then the throttle if you could get this plane to hover better with a Fox doing the break?

I doubt it, Paul. Mine hovers on what seems like only about 1/2 throttle.  What is more significant than the weight of the model is its induced drag, courtesy of the very low aspect ratio.  This is what makes it such fun to fly, and is also why it helps to have a lot more power available if you need it. I'm sure you'd have a lot of fun with a Fox, but for a good stable hover I don't think you can beat proper throttle control.

[Tom Niebuhr]

Many of you know that I wrote the BiSlob FM article and drew the original plan with Ron Pavloer's input.

Ron always said "Build it Light!". In fact our ribs always had lightening holes in them, unlike the Brodak kit.  

Adding throttles or pulling the tail with a line as some have done, is not necessary.

As many have said the Fox .35 is perfect. Ron Pavloer also flew some of his Slobs with an early Fox .25.

I have never had trouble with the Slob reaching the top with a Fox .35. In fact, it is part of doing a slow slow wingover starting with the wind at your back.

We also have no trouble making it Sabre Dance (hover) and climb up and down while in the hover. All controlled with a little finesse with the elevator. I also have gone into the hover right from the take off, and also with someone launching it in the verticle position.

Above all remember that the name of the airplane is BiSLOB. Never pretty and the burned head of a Fox just adds spice to the name!

[Fred DiMaria]

Bi-slob update:

I added about an ounce of tail weight, and a half ounce to the outside wing, and changed to a 10-4 from a 9-6. (engine is a Max .25 FSR R/C).

I ran the engine tied to about 3/4 throttle, and went at it today.  It flew better and seemed more responsive, but when I tried to get into a hover, it simply flew into a slow wingover, it just flew up and over. This happened a few times, so I was pretty sure I had the throttle too high. I only got one flight, however, as I decided to fly a few loops, one went great, the second was a figure 9, right in. Only damage was a broken rudder, but done for the day. Its hard to make progress with these one flight outings!  Arrggh.

[Paul Taylor]

One thing to try.
When doing the slow wing over - flutter the elevator. This might make it hover a little.
Something Joe Gilbert told me.

[john e. holliday]

Or fly when there is a little more wind.   I too, the first time I tried to hover, wound up doing a reverse wing over into the wind.  Then I opened the needle a click or two.   It takes practice, but once done you wonder why it was so hard to learn.   

[Fred DiMaria]

How much control throws are normally used on a bi-slob to hover it and do some of the vertical aerobatics that it was designed to do?  I may not have enough control throws, I have the pushrod on the lowest hole on the control horn.  The problem is, the plane is fairly twitchy as it is, and I am afraid it may be too touchy to fly if I increase the throws even more.

Also, is it fair to say the flaps should be neutral when the elevator is neutral, or can they be in a slight down position?

[john e. holliday]

I think mine are about 35 to 45 degree movement.   Remember the old Fox only needs enough power to get airborne.   then lean out when nose is pulled up.   Fly on shorter lines than normal, like about 55 foot, I myself still use 60 foot center to center, plane to handle.  Also a low pitch prop.  I am using a 10-4 Power point by top Flite.   Another thing that was pointed out to me was to watch how long you are flying as time will get away from you and it can get exhausting doing all the loops and prop hanging.

[Tom Niebuhr]

I don't know what the Brodak plans show for control movement. The control throw that I drew on the FM plans is correct. It is approx. 85 degrees elevator and 45 degrees flap. It will be a little twitchy but it works great.

As I said above Ron Pavloer used both Fox .35s and early versions of the Fox .25. The Fox break is perfect. Every time I have seen people try to "improve" on the Fox, it doesn't work as well.

I use a 10x6 prop and 55ft. lines. There is no reason to over complicate things.

One of the most important things to remember is that the Slob likes to have wind on your back.