Peter G.

Randyl

I think that has been one of my problems, just not believing the cg. could be sooooo far back. Last fall it had a very bad habit of snapping left or right with even the most subtle turns, basically unflyable. I guess I now know what a supper nose heavy plane acts like.

Thanks.

big max 1935

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Wait till you boys build a Pacer B or C . CG is way back & air- foil on stab is on the bottom ,with a whole lot of incidence in stab. That is probably the best flying Old Timer I have built ,very strong. I have the Pacer C with a OS 25 FSR in it & it is impressive!
>>>>>>>>>>>>>>big max 1935>>>>>>>>>>>>>>>>

BMatthews

Peter, it sounds like what you were experiencing was that Dutch Roll thing discussed in another of the posts here.

Moving the CG back will actually reduce that tendency.

If you're worried about the elevator control becoming too sensitive then just reduce the throw. Trust me, the model will be happier with it back at the 45 to 50 percent mark.

You can fine tune the setting by using the same stability setting tool that the sailplane guys use. Get the model airborne and when in a stable glide push over into a 45 degree dive and then neutralize the stick and watch (at altitude of course... ). The model should nose up back to normal flight but you want it to do this over a few seconds and not in a quick whoopy roller coaster ride type pullup.

A good setting for the balance, and the resulting elevator trim, of a model of the Playboy's size is for such a dive to drop about 80 to 100 feet before bottoming out and nosing up. There will be a bit of a stall as it noses up but that's fine. It's that first recovery you are looking for. The 80 feet is about as "stable" as I would want it and the 100 or so is an excellent point to shoot for. If it goes to 150 or more or shows signs of tucking under then you're too far back. But I doubt if you're in any danger of seeing this from your present setup... This sort of pullup altitude is what I would set up any sort of soaring model for be it a modern glider or my Old Timers. You'll notice that it's cruise glide speed is slower and indicates thermals better with this setup also.

Those recovery heights are typical of my friends free flight model and it's a lovely flyer. In fact it only did these stalls during his test phases. It hasn't shown such nasty behaviour ever since.

RandyL

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I'm feelin' like the whippersnapper here.... I've not ever heard of a Pacer.....b,c, or otherwise! Got any pics?
I've got some Powerhouse plans, and a Buccaner I believe. What the heck is a Pacer???
Appreciate the glider trim info too, I'll be palying with that when things warm up to see if I can trim the Playboy for better flight time.
Interesting thread, hope you get yours flying good Peter.

big max 1935

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RandyL ; A camera is one of my top priorities! Power House, Pacer,Brooklyn Dodger & Many others were designed by Sal Taibi. He won (I THINK) 1940 class B at Nationals. My flying buddies call it the Flying Flounder . The glow plug is right under the front peg for the wing hold down rubbers. A very Tough little bird ,60" span.
I hope that when the AMA gets all of John Ponds plans sorted out ,that they can come up with three views of some of the more popular planes. Glad to see you guys are getting your Playboys sorted out. >>>>>>>>>big max 1935>>>>>>>>>>>>>>>

BMatthews

Big Max didn't mention that the Pacer setup with the inverted lifting stab and crazy amount of positive incidence on the stab is an odd ball in the free flight world. There was some story about how Sal Taibi was trying to trim the original and it was just doing crazy stuff. Someone supposedley suggested the "upside down" stab and positive incidence to fix it and Sal was just desparate enough to try it. Funny thing was that it worked. The rest is history.

RandyL

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Generally speaking, when the tail is upside down on my airplane my whole airplane is inverted! I'm congering up an awful ugly picture..
All this chit chat got me outside this afternoon. I charged up the Playboy and put the 2nd flight on it. Winds were calm, mostly sunny and around 30F. I had to miss the snow patchs for a take off but it was well worth the effort.
After 12 minutes of gentle flying I lined up and set it down a few feet from me. Number 2 in the books and all was as perfect as could be.
I tried the glider tirm thing with a 45 degree down ( motor off ) and it returned to level and nose high sorta stall right away. It took only little time to come out of the dive. I need to re-read the above post and see what that means.
I also checked the CG with the wing on. I have no measurement but can tell you by looking at where my fingers were located that I am balancing at 50% back...maybe a smidge ( is that still a word ?) further back than 50%....
Its about dark, and its been a good day!

BMatthews

Randy, I'm envious. It's been grey and miserable all day here. And I'm fighting some bug that has my balance all whonky.

Sounds like it's still VERY stable. If it's any help to add to my bit from above the time that pullout takes for the free flight version is about 2 to 3 seconds to reach level at the bottom of the first recovery. With the extra speed related to the electric weight this may be a little faster. But look for the height change from when you first neutralize the stick to the model being level at the bottom of the pullout.

I've got an electric powered Record Hound that balances at about 60% or perhaps even further back and it's STILL too stable. But I can't bring myself to do the surgery to the nose or add more weight to the tail. It's already heavy at 56 oz. The elevator throw is about 1/2 inch total from full up to full down and the elevator is about an average of 1 1/2 inches wide if that helps you guys that are worried about the elevator becoming too sensitive.

Gotta get that puppy flying again this spring.....

big max 1935

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Back in early 40`s a Canadian by the name of Bruce Lester had a 80" ship that was a clone of the Pacer called the Blitz Buggy. It was so close to Taibi`s design it makes you wonder who came first . The outer wing panels were swept back some, but all else was very close. Built one thinking it would be easier to see with my old eyes. Had a super slow glide then all at once it would drop it`s nose straight down. It would never recover by it`s self. Gave a large pucker factor !! Finally fixed it by adding washout to wing. Later sold it , may be floating around here some where yet! These old birds are a real challenge!>>>big max 1935>>>>>

BMatthews

Ya know Max, that sounds suspiciously like the Pacer story. At least it lit a little candle deep in the back of my mind. I wonder if that's what happened to Sal's Pacer? Did you Buggy have the tail lifting side up or down?

I don't think the origin of the cowled in engine should be any surprise. Sal and Bruce weren't the only ones to hide the engine in the pylon around that time. The Go Getter is another for example and I'm sure there were a few others.

My own Record Hound wasn't far off that school of design with trying to hide the engine and landing gear in that deep cowl.

big max 1935

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Bruce ,I had the stab with the air foil on bottom on the Buggy. My Pacer I put it on top. Taibi told that if the engine quit at low altitude the Pacer didn`t have enough altitude to recover from dive, poor transition at altitude also . Inverted stab cured it all.
Think mine just flew so slow that the whole wing stalled at once & once the wash out was in it changed stall speed. The Buggy was pretty good then. Have a Goldberg Sailplane with a Wankel on it about ready for summer. Built in Minneapolis in 1946, had aged balsa in it!! >>>>>>>>>big max 1935>>>>>>>>>>>>>>

Sideport

Peter, I have 3 Playboys, 2 are used in compition and 1 for sport.
This morning I measured 2 and came up with the same answers. I was quite surprised, but these are both SAM competition models.
One is a 900" Nelson .40, the other is 678" ST.29.
The measurments were made with a Robart Incidence Meter.

Stab. 0 degrees
Wing -1 degrees
Eng. -4 degrees
Eng. side 0 degrees
C.G. 50%
Rudder throw low1/2" high 1"
Elevator throw low 3/16" high 3/8"
Add about -20% expotental. This will help the dutch roll or the playboy rock.
Regarding lifting stabs. If it is a flat bottem airfoil, you can safely move the C.G. back to 55%. Some of the mid 50's freeflight stabs. were as large as 42% of the wing area, and the C.G. could be moved back to 90% of the wing cord. On the other hand if the stab. is flat on the top and bottom or or semicrectal I would go no farther back than 35%.
I hope this will help you enjoy your Playboy Sr.
Al T.

RandyL

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We're gonna make you get it out and fly it Peter....may as well get on with it!

BMathews... I sure hope you get over your bug, not having balance or getting vertigo would not be good for model flying!

As it stands right now the weather is looking up for Saturday. Maybe I can get some inflight photos.

Peter G.

Gee thanks guy's, I am going to check it out with my incidence meter and see what I get. My air strip still has a bit of snow yet so It might be a few weeks yet before I try again in 2003. I want to install heavier wire for the landing gear. Even though the right diameter was used it is way too wobbly on a rough grass strip.

By the way, both the wing and the stab are under-cambered.

big max 1935

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You boys might try a Cabin Playboy , they seem to be a lot better in wind. Always seem to do better with cabin models for our kind of event. >>>>>>>>>>>big max 1935>>>>>>>>>>>>>>

Donk

Sideport:
You have some awesome engines there. I don't think I would like to compete with you!
I had trouble with rudder authority on the Playboy Cabin, especially on landing in the wind. How about you?

My current love is with the Lanzo Racer..

RandyL

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My wing has a nice undercamber but the stab has a flat bottom, nice airfoil, but flat bottom.
Also, my plans show the cabin version Playboy so it could be built either way. It only came with wood supplied for the Pylon version but could easily be built in cabin configuration.
I wanted the pylon version as it has a classic look, or at least to me it does. I like it!
Hope your snow is gone soon.....

Sideport

Donk:
The Playboy is not one of the best models for windy weather. I suspect that the cabin version blocks out the rudder even more. Although I don't fly the cabin version I still use high rates on take off and landing.
Incidently the cabin version was added to the plans when another manufacturer came out with a new cabin model.
Did you get to Muncie last August for the SAM Champs?
They are going to return in 2004.

Al T.

Donk

My favorite planes from a pilots point of view are the Racer and Dallaire. They both respond so well and are stable on take-off.
In the right hands they can win the contest but not in mine. I'm just one of those "dick around" flyers.

I rode my motorcycle down to Muncie twice during the SAM Champs last year but just observed. Living close gives me a lot of opportunities to see great flying.

Flight Risk

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Hey all! This is an old thread but I found it very informative about the CG and flight characteristics.
I have recently acquired an older built version of a Playboy Senior. It has an 84" wing and came with a .40 Surpass and an AM receiver. The engine was all gummed up (especially the valves) but I freed it up and it is currently running nicely on another model. I have a new flight pack I am ready to install and I will either reinstall the Surpass or an old McCoy Redhead .35 with carb.
This model looks similar to the current Ben Buckle model, except the Ben Buckle is listed as 80" and mine has a tail gear which looks like an amateur job. Also mine has a half-width elevator.
Any ideas of how long the Ben Buckles have been in production or other ideas on manufacturer?
I thought this would be a nice gentle flier to install a camera on.

RS

powerglide

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Last yr I built a wasp, 50 span with the undercambered wing, the one it said to build. nomatter what I tried the model would want to veer off right or left. I mean I tried everything to make it fly striaght, so fianally wound up making a clark-y wing, flies like a dream eversince. I went electric, speed 400 geared 3-1 10-6 wood prop.the c/g was approx. 60% which is right for the o/t models with big stabs,I also had to add about 3 oz wieght on the nose to make it fly right , didnt really want to ,but it was that or bring the nose out, would strongly advise electric unless your hardcore gas

RandyL

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I'm still flying my Playboy. Couldn't say how many flights I have put on it since the start of this thread but I have made no changes...It still fly great.
The Master Airscrew gear box with the 05 and 7 cells makes nice long flights. Enjoy yours!!

RandyL

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Today being a national holiday here in the U.S I put my 05 gear powered electric 73 inch Playboy model to work.
It worked well to pull a flag around the patch even in the very hot and breezy conditons. The flag pulling along behind requires that you make large turns as it ceratinly would prefer to go straight ahead at all times..
The flag is probably a bit over a foot square and is made of light weight plastic. I used a 3/16 balsa stick at the front of the flag with a small nut glued on the bottom of the stick. Kite string completed the project. It never tips over or rolls around...just flaps in the breeze as it should.
Dead batteries in my digital camera prevented pictures of it closer in on later laps..
Possibly you all can use this idea for celebrations in your own countries. It is much more impressive than the long range photo shows...
Happy 4th of July!

powerglide

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looks good partner!!!! cant beat those oldtimers for profile, was just out flying a model on floats also with a flag behind it, what a ball

powerglide

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what??????>>>>>>>>>>>>.anyone remember that old scifi movie called "THEM, with james arnez and some others, anyway I believe it was shot in LA with those big empty water ways< or whatever they were called???? some guy in the movie found a F/F model,but never did see which model is was, anyone see that movie and what model it was????almost looked like a zipper??