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Playboy

Old 08-02-2002, 03:15 PM
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Peter G.
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Default Playboy

I have built one of those old fashioned playboys where the wing is almost directly behind the fuselage. I believe the balance point to be at approx. 27% of the wing cord, but could not get the plane to balance there. So while still in the building process I moved the wing further back. The plane does not seem to be be at the right balance point. It takes over 1/2 inch of up elevator to get the plane to come up off the ground. This plane is one of those with a airfoil built into the tail feathers as well. Anyway would anyone know the correct balance point for the Playboy. I have noticed on the net. that some similar looking planes have the balance point at almost 40% of the wing cord. Thanks.
Old 08-02-2002, 03:45 PM
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JohnBuckner
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Default Playboy

I suspect you made a mistake moving the wing back. Now I have not built or flown a Playboy but have built and flown a few other similar earloy pylon freeflights with the same type of decalage arrangements including a 'Kerswap' which flys nicely at 60%. Others of this type seem to run in the 50% range,
27% is severely nose heavy for the playboy.

John
Old 08-02-2002, 07:35 PM
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Peter G.
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Thanks John, although this is not a free flight, it's powered by a .35 I suspect the balance point should be around where you say. It should not be a big problem moving the balance point further back though, since I cramed the battery pack just behind the firewall. If I move it back 4-5 inches I suspect it to be close.Thanks again.
Old 08-02-2002, 11:33 PM
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You Bet Peter, and I should have used the term radio assist free flight meaning a free flight design that was later converted for a radio assist.

A word on flying these types if you like. After takeoff under full power the ship will assume about a forty degree deck angle and there is no why to hold the nose down at that power setting. There are two ways of flying them with radio. The first is to hold full power and let it take its head untill reaching whatever altitude then throttle back to just over idle and the airplane can assume normal attitude and moist of the flight will be at idle or say 25% throttle position. Any attempt to sustain high power in any other than a steep climb will result in extreme directional instability and dutch roll. The solution is to just get off the power. Airplanes of this type and decalage were designed for extreme pitch stability and no mater what you do with power or elevator will just push it into dutch roll.

The other method is to reduce power just after hand launch or ROG to a low power setting and you will be rewarded with a beautiful low and slow tottling flight. Probably the best way to think of the controls is the elevator is a minor trimming device and the throttle is an altitude control but not a speed control. The ship is going to fly at one speed no matter what.

You will love this airplane.


Just what works for me
John
Old 08-03-2002, 10:30 AM
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EASYTIGER
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Default Playboy

Moving the pylon back is not a problem at all. Better than extending the nose to acheive balance. I think you may have gone a little too far, though. With the lifting stab, the balance can be further aft than usual.
Old 08-04-2002, 02:54 AM
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ajcoholic
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I have built 3 PB Sr's and my current one (powered by an Atwood SCJH on ignition) balances at the 45-50% back from the LE position. To acheive this I merely spaced the engine off the firewall about 3/4" to get more of the weight out front. At full throttle (the only setting on my Atwood!) the PB climbs out near verticle and just hold a lot of down elev. to keep it from falling on its back. Just before you kill the engine push hard forward so you dont lose any altitude stalling it when you stop the engine/lose your momentum. ENjoy the glide!

Andrew Coholic
Old 08-04-2002, 10:00 PM
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Peter G.
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I assume that you are using the Playboy as a powered glider, or do you mean when you kill the engine upon landing. The Playboy I built was intended as a slow flyer and has a 50" wing span.
Old 08-04-2002, 10:56 PM
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ajcoholic
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I fly my PB Sr. in SAM (Society of antique modellers) competitions and also for fun. I am using an original ignition engine from the late 40's and therefore it has no throttle (only full bore or stopped!). I did however fly my other one with a .29 K&B torp I added and rc carb too, and it makes a great "puttering" around job. Very easy and relaxing to fly. That however should make no difference to the balance point. Also, All mine were original 80" size but if you scale it down the CG position is still in the same relative position, as long as your horz. stab is still airfoiled.

HAve fun!

Andrew
Old 08-05-2002, 01:59 AM
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Peter G.
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Thanks Andrew, I hope with this info my son and I are well on our way to having a fun flying airplane.
Old 08-05-2002, 08:20 AM
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suman
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Default Playboy

Peter G:

Did I hear you right? You put a .35 on a 50" span Playboy? This is too much power for such a small plane, even a pylon job like the Playboy. I would recommend no more than a 21, a 15 would be great. I have a 54" one I fly with a Norvel 061, in fact. Built very light and a great climber and glider. I have another one I am getting ready for competition: 54", with a hot Cox 15 on it.

I suggest you try a smaller engine. A .35 is waaaa...yyyy too much power. There will be no way you could prevent the plane from power-looping, even with all down elevator.

A 35 would be just right for a 72-80" Playboy.

Suman
Lawrence, KS
ssk320@yahoo.com
=========================================

"Thanks John, although this is not a free flight, it's powered by a .35 "

"The Playboy I built was intended as a slow flyer and has a 50" wing span"
Old 08-05-2002, 03:09 PM
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Peter G.
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OOPS. sorry about that, it's actually a 70" (69 and some). I have had it in the air for a short flight and was luky to bring it down ok, thats how I know I needed 1/2" of up elevator for level flight. The plane was built according to plans with the reccomended engine size. For some reason I no longer could locate the balance point in my write up. I think all the suggestions from this forum on balance points will help a good deal. Thanks
Old 10-04-2002, 12:02 PM
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Default Tritex Playboy

Hi,

I read the posts concerning vintage versions of the Playboy with great interest.

Am hoping to return to hobby after many years with an electric version of the Playboy marketed in the States as an electric ARTF kit by Hobby Lobby.

With its light wing loading, long tail moment, polyhedral wing and bouncy undercart, I thought it might be a great electric trainer.

And I like the looks as well :-)

Would appreciate your views and experience with this model in particular, but any views on the Playboy in general would be most welcome.

With thanks in anticipation,

Khairil
Old 10-04-2002, 01:57 PM
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Peter G.
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Khairil

Id like to say I have a lot of experience with the playboy, but from this thread you should see that I am having a good deal of problems with it. I suspect it is not the aircraft but rather not knowing the correct cg. I am told it is a good slow flier, however everything I have ever flown was easier, again no doubt that it is not balanced/trimmed correctly. Sorry I can't be of much help.
Old 10-04-2002, 03:30 PM
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ajcoholic
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A properly trimmed Playboy in ANY size with a decent wing loading (10 oz for 1/2A up to 14 or 16 oz per sq. foot for the full size) will make an excellent trainer and fun plane. Even good for thermalling!

Had three (one currently) and they all flew excellently hands off. After all, it is a winning FF design!

Andrew
Old 10-25-2002, 06:34 AM
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Default Playboy

Originally posted by ajcoholic
I have built 3 PB Sr's and my current one (powered by an Atwood SCJH on ignition) balances at the 45-50% back from the LE position. .......

Andrew Coholic
Peter G, you need to pay attention to the post I've quoted above. It won't matter how you want to fly your Playboy, the balance point still needs to be back in this 45-50% range.

Don't worry about making it super sensitive or having it whip stall on you or anything like that. The long tail moment and generous stab area all work to make the stability margin safe with the rearward CG.

I have an electric powered Record Hound and it's flying with about a 50% CG and I'd actually like to move it back even more but that would require major surgery or tail weight. I also fly a Roger Hammer Flamingo on radio as a slow flyer and it's running around with about a 40% CG also. (BTW, the Flamingo is 84 inch span, 5 1/2 lbs and I fly it with an old OS 35)

All that up elevator is trying to tell you something. It's not happy.
Old 10-25-2002, 04:07 PM
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Peter G.
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Default Playboy

Thanks Bruce:

I have not given it a fair go since moving the cg. back. The landing gear I have never been happy with, she waddles a lot down the runway. A LOT. You have to be on your toes to take off when she is straight. I bought some aluminum gear but did not put it on yet. Ive been busy with some other aircraft but will come back to her. I have a rough grass strip and she would probably be ok on a paved one. I know .......... some guy's hand launch them, or so I am told. I can tell you I have had more problems with this one than any of the others. But again if I did not have the correct cg. that would explain it all.
Old 10-26-2002, 12:45 AM
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ajcoholic
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On my PB's (seniors) I used 5/32 music wire gear I bent up and attached to the firewall with landing gear straps. They run straight and if you are wadelling, perhaps the gear isnt stiff enough? Aluminum gear on an old timer wouldnt look right to me!

As for the flying, if the incidences are set up right, you should need no up elevator at all, actually, under full power yuou might need some down trim (I do) to keep from ballooning up. I like to trim by doing a power off glide, and see how it stalls. Center the elev. and if it dives,nose heavy, if it stalls and porpises, needs some nose weight. Or I slightly move the wing back or forward instead of adding/removeing weight. Also, my current PB was tail heavy so I spaced the engine mounts out 1/2" and it balanced spot on without adding more weight.

ANdrew
Old 10-26-2002, 02:15 AM
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Peter G.
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AJCOHOLIC;

I have 5/32 landing gear wire and the plane weighs approx 5 lbs. I am curious as to what your incidences are. At the moment I have 0% - 0% - 0% but have tried some down thrust in the motor. I now have it balanced at 48% of wing cord. I have a old .35 merc. on it. Thanks.
Old 10-26-2002, 11:44 AM
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Peter,
I dug out the plans and here is the info. By the way, the plans I use were for an RC conversion of the Playboy Senior, published in RCM magazine. Its a faithfull copy of the original, save for the moveable tail surfaces.

My stabaliser is set at 0 degrees. My wing is set so the leading edge is 1/4" higher than the trailing edge when sitting on the pylon, this measurement is relative to the centerline running through the fuselage. Dont know what angle that is but probably about 3 to 4 degrees positive.

Engine is set at zero.

The balance point is 45 to 50% back, actually mine balances right on the small lower spar behind the main spar, if you know which one I mean.

5 pounds is a bit heavier than mine (I believe mine is about 4.5) but it should fly fine with that big wing.

Hope that helps!

Andrew J. Coholic
SAM 4659
Old 10-26-2002, 04:07 PM
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Peter G.
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Thanks ajcoholic I'll compare that info to mine.
Old 03-02-2003, 02:12 AM
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RandyL
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Default Playboy

Howdy all you old thread readers... or should I be nice and say Howdy to all of you that read old threads.

I just finished up a Playboy Senior kit by Leisure Electric. I think the kit was produced in 1984. I almost hated to build it as the wood was beautiful.
Leisure had taken the Playboy model ( 67 inch span ) and converted it to an electric. It is built exactly as per plans right to using the 2.5 - 1 gear driven 05 can motor on 7 cells.
It was wobbly kneed on the takeoff as the gear wiggled a lot, it is only 3/32 wire but I will brace it a bit and all will be fine there.
All up weight is 3 1/4 pounds and it flys gorgeous! I have a total of one flight on it but it was a nice one. Once airborne I throttled back and enjoyed a 14 minute flight.......so, so pretty doing low, slow flybys.
I still need to do more trim work for looks before summer but it is a winner. Just wanted to post a good word for the Playboy design.

Randy
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Old 03-02-2003, 02:43 AM
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RC Report had one of their build & fly articles a few years back on it. They were disappointed that it weighed so much. A great amount more than manufacturer specs. They had to add a lot of lead to balance. Where balance was I don`t remember, have magazine some where in my "piling system". Built one a few years back,RC assist, powered with a K&B 21, took it straight up in a climbing turn. On a still day was always good for 10 minutes +. This one was balanced 1" forward of trailing edge.
>>>>>>>>>>>>big max 1935>>>>>>>>>>>>>>>>>
Old 03-02-2003, 05:23 AM
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Peter G.
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RANDYL

Glad to hear everything went well. I still do not have mine flying right. Hey it's in one piece still.

What was your balance point? Might help me to confirm things a bit. Thanks.
Old 03-02-2003, 07:57 AM
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Default Playboy

Peter, I've got a buddy here that has a free flight version the same size as yours. I'll check with him to find out where his model balances.

It just does NOT matter if it's got radio or not in the model. The design is going to be happy with the CG in one area for both.
Old 03-02-2003, 05:54 PM
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RandyL
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I unrolled my plans to see where the CG is marked. Just short of the 50% mark. Probably would work out to 45% of the chord. I know when I got it built and ready to check balance that I was VERY shocked to see what it showed on the plans. I had not paid any attention to it at all during the building stage. Knowing it had a lifting stab I went with the plans ( or very close to it ) and it flys just great.
The airplane is loaded in my van currently or I would actually check it again to verify. I do know that I did not stray far from suggestions on the plans however. I suspect a check will show that I am slightly ahead of the 45% cg as it had me scared that far back..I am not used to such things.

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