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Playboy Senior

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Andy Hat05/08/2019 16:05:07
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64 forum posts
42 photos

This is my just-finished Ben Buckle Playboy Senior.

I was careful to try and build it light BUT I've really messed up - there's no way I can get it to balance on the plan CG.

Perhaps I should have used a larger motor/battery combination (currently 3542/2200mah) but I calculated this would be adequate power. I moved the motor further forward but it made little difference.

Even with 420g/15oz of lead hanging off the prop adapter, it's still no where near the correct mark.

I've read that 50% might be adequate from this model but any experience or suggestions you have would be gratefully received.

playboysnr.jpg

paul d05/08/2019 17:42:12
70 forum posts
5 photos

Double post!

 

Edited By paul d on 05/08/2019 17:46:11

paul d05/08/2019 17:45:37
70 forum posts
5 photos

That's the trouble when converting vintage models to modern electrics, it was originally designed for a heavy old sparky.

First thing I would do is replace those rather small wheels with some big fat airwheels.

I presume the battery etc are as far forward as possible?

Try giving it a test glide, you'll be surprised how tolerant those old timers are to the cg position

Bob Cotsford05/08/2019 18:38:14
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8032 forum posts
444 photos

The other problem with these vintage designs is that the nose is so short that the slightest increase in weight at the tail needs a shedload of lead in the nose to correct it. You have something like a 5 or 6:1 moment at the tail judging by the photo.

Dad_flyer05/08/2019 23:42:42
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161 forum posts
170 photos

I have acquired a Double Diamond. The previous owner had similar issues to you, as in this thread.

The end was 620g of lead in the nose. Flying it is lovely, even at 9lbs total weight and just 400W at full throttle with a fully charged battery.

Chris Freeman 306/08/2019 05:37:49
273 forum posts
355 photos

A playboy is a great flying aircraft, I built one for a mate about 10 years ago and it is still flying. The undercamber wing and pylon arrangement were designed for maximum climb rates so the Playboy will climb under power so it may be best for initial flights to use limited power after a launch or take off. We tend to hand launch the playboy as it must be directly into wind. The cg can be further back than normal aircraft. Best to set up your rates on the radio as well. I am sure you will have lots of fun with it.

SIMON CRAGG06/08/2019 06:33:29
477 forum posts
15 photos

I regularly fly mine, which I have recently refurbished. The only way round the problem is to extend the nose. I have flown mine with a variety of engines and currently have an ASP .52 installed. Nose needs to be extended at least a couple of inches.

Broken Prop06/08/2019 08:00:07
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603 forum posts
1 photos

Hi Andy

I had the same problem with my Playboy Senior and finally settled for a CG position at 40% of the wing chord. Even so lt needed about 12oz of lead attached to the bulkhead and quite a lot of down elevator trim.

It still exhibits 'homesick angel' tendencies. Make sure that you get the engine tickover as low as possible otherwise it will float on and on when attempting to land.

It is a lovely plane to fly.

brokenenglish06/08/2019 08:28:41
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464 forum posts
29 photos
Posted by paul d on 05/08/2019 17:45:37:

That's the trouble when converting vintage models to modern electrics, it was originally designed for a heavy old sparky.

First thing I would do is replace those rather small wheels with some big fat airwheels.

I presume the battery etc are as far forward as possible?

Try giving it a test glide, you'll be surprised how tolerant those old timers are to the cg position

This is very misleading. The old sparkers normally used are very light, far lighter than modern engines. Browns and Ohlssons weigh less than a modern engine of half their capacity. OK, the light weight of the old ignition engines is partially offset by the weight of the ignition system, but the engine + ignition system will still be lighter than a modern four-stroke.

The problem is more due to "modern" builders not realising that this type of model has to be built very light aft of the wing, and particularly at the tail end, obviously. Modern coverings don't help either... Then the problem is aggravated by the use of electric power, where the main motive power weight (the battery) isn't in the nose, but further back, at least behind the fire wall, and this is very significant in the case of a short-nose model.

My advice would be to get everything as far forward as possible. Then add whatever ballast is needed to get a CG at around 50%, and fly it like that. It should be fine.

brokenenglish06/08/2019 08:30:24
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464 forum posts
29 photos
Duplicate post. Sorry!

Edited By brokenenglish on 06/08/2019 08:32:10

Andy Hat06/08/2019 09:17:51
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64 forum posts
42 photos

After fitting larger/heavier wheels (+100g), bending the u/c further forward and adding 240g of lead in the nose, it now balances on the middle lower spar which is about 50% of the wing.

The total, ready to fly, weight is 1760g - which includes the 198g 2200mah 3S battery (which is against the firewall).

I'll try it out when the weather improves and report here.

Thank you all!

ken anderson.06/08/2019 10:55:13
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8454 forum posts
773 photos

i have a junior 60 with 1/2lb of lead in the nose...it fly's and floats like a goodin….any space/gaps at the front,put in some lead...

ken anderson...ne..1..... flying lead dept.

Bob Cotsford06/08/2019 11:12:36
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8032 forum posts
444 photos

Replace some of the lead with either a bigger battery or a second 2200?

Capt Kremen06/08/2019 11:19:30
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300 forum posts
83 photos

As others have mentioned, the tail end, (especially), needs to be kept light.

I built a vintage 'Air Trails', Ray Heit design the 'Scrappy', (similar to the 'Scram'. All traditional fabric and doped covering, couldn't get it anywhere near a safe balance point. In desperation, I ended up recovering the tail plane and fin/rudder assembly in tissue. I was amazed at just doing that simple little thing, made a huge difference to achieving a safe flyable C of G.

Also, with the advent of LiPo replacing the 'lead weight' NiCad cells of earlier electro-flight days, that has made the C of G balancing act more of a challenge!

Djay07/08/2019 07:56:23
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543 forum posts
445 photos

I downloaded a plan a couple of years ago and made one of these .

Do not worry at all about the weight, the wingspan is so big and fuse so small you could double the weight and it will fly without any issues.

Mine is powered by an OS 26 4 stroke and is way overpowered.

It takes off in a few feet and will climb at 80 degrees like a homesick angel, then it flies at nothing more than tick over for ages, I usually just let it free fly and use the trim on the TX to change course or height as it hardly needs any input. flies at anything from backwards in a wind to very slow walking pace to a couple of miles an hour, not designed to fly fast. In a wind it will hover or go backwards for ages, fully under control.

Do not try and fly it like a modern plane as it was designed for free flight, so let it do its own thing and enjoy it. it is virtually crash proof even if you put full control inputs in

My C of G is about 75% back from the L/E as per the original plan, but it really does not matter as long as it is some where within the wing forward of the rear spar and aft of the L/E.

Do not put the C of G forward like a modern plane, again these designs are different to them. If you can view the original plans on the internet and see the notes and C of G on them.

I have an album with some construction images in if you are interested.

Darryl

20160902_062133 (copy).jpg

paul d07/08/2019 08:01:45
70 forum posts
5 photos

What a lovely looking model Darryl!

Andy Hat09/08/2019 13:56:50
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64 forum posts
42 photos

I flew it yesterday and it was great. No trim or extra weight needed. My problem now is learning how to get this plane down. It just didn't want to come out of the sky. Very pleased!

Dad_flyer10/08/2019 21:35:54
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161 forum posts
170 photos

yes

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