Author Topic: Design generalities (Read 6156 times)

Matthew Brown · « **on:** June 11, 2016, 07:45:54 PM »

Over the years I have seen many design aspects looked at as ratios and percentages. Years ago when I flew fast and slow combat a lot of the overall design aspects were very similar between different designs. Things like aspect ratio, wing area, tail moment and area etc.
As I am now wanting learn more about stunt planes I was wondering if there is a listing of these parameters such that I could use them to apply to my own designs.

Thanks, Matt

Tim Wescott · « **Reply #1 on:** June 11, 2016, 10:16:16 PM »

There isn't one hard and fast formula, but most of the top guys in the US fly planes that seem pretty similar.

Reading all the posts here is a good idea -- there's lots of bits and bobs.

Too many, in fact, for me to want to list. Read up, don't hesitate to ask questions. "Why" is a good one, if someone tries to tell you "just because". Figure out who actually wins contests and listen to them more.

Mark Knoepfle · « **Reply #2 on:** June 12, 2016, 09:24:47 AM »

See Netzband Stunt Design Summary.

http://www.pampacl.org/index.php/resources/category/14-general-articles

Matthew Brown · « **Reply #3 on:** June 12, 2016, 10:07:07 AM »

Quote from: Mark Knoepfle on June 12, 2016, 09:24:47 AM

See Netzband Stunt Design Summary.

http://www.pampacl.org/index.php/resources/category/14-general-articles

After a quick look, this is exactly what I was looking for!
Even from my naive eye, most modern stunt planes looked extremely close after stripping away the finish and aesthetic lines. Bill said as much in his article.
I figured if I decided to roll my own, with these numbers I could come up with a decent flying design.

Matt

Steve Thomas · « **Reply #4 on:** June 13, 2016, 08:17:29 PM »

There are a couple of good articles by Brett Buck and Randy Powell in the July/August and September/October 2007 editions of Stunt News - well worth a look.

Howard Rush · « **Reply #5 on:** June 13, 2016, 08:53:10 PM »

Quote from: Basmntdweller on June 12, 2016, 10:07:07 AM

I figured if I decided to roll my own, with these numbers I could come up with a decent flying design.

If you got the details, which weren't mentioned, right, you would have an airplane that flies as well as the average airplane from 1946 to 1996.

Brett Buck · « **Reply #6 on:** June 13, 2016, 09:40:19 PM »

Quote from: Howard Rush on June 13, 2016, 08:53:10 PM

If you got the details, which weren't mentioned, right, you would have an airplane that flies as well as the average airplane from 1946 to 1996.

An interestingly, I would only consider 4-5 of them to provide winning-caliber performance. I will let everybody else argue over which 5!

Brett

Matthew Brown · « **Reply #7 on:** June 14, 2016, 05:03:36 AM »

Quote from: Howard Rush on June 13, 2016, 08:53:10 PM

If you got the details, which weren't mentioned, right, you would have an airplane that flies as well as the average airplane from 1946 to 1996.

That's likely true but I'd bet that average performing plane would be way better than anything came I up with without using any of those numbers! Also, that average plane would still be better than what I'll ever be as a flyer.

Matt

Mark Scarborough · « **Reply #8 on:** June 14, 2016, 08:10:54 AM »

Quote from: Basmntdweller on June 14, 2016, 05:03:36 AM

That's likely true but I'd bet that average performing plane would be way better than anything came I up with without using any of those numbers! Also, that average plane would still be better than what I'll ever be as a flyer.

Matt

One of the things that gets glossed over occasionaly, mostly because we that frequent this part of the forum are "serious" stunt people who are striving to elevate our game as high as possible, is that some people really dont care. What is your goal, are you just wanting to fly a cool looking airplane around in circles and occaionaly do some tricks, or are you wanting to fly competativly and or fly the pattern in a sport mode..... it matters some,,
However all that rambling stated, copying a current technology as in since the late 90s , design will be most likely a better starting point than an older design. AND more importantly, the better the plane flies the more fun you will have even if all you do is go around in circles with an occasional loop thrown in.

Mark Scarborough · « **Reply #9 on:** June 14, 2016, 08:17:20 AM »

also, and more importantly,, if you pick the wrong details and combine them, you will have a chocolatey mess instead of a good flying plane. I think this is what Howard was trying to point out. You cant just pick one number from here, and another number from there, and if you just happened to pick all the right numbers from desings in the seventies, then your plane might fly as good as a plane from the seventies
it is horribly important to not loose site of the fact that an airplane is a SYSTEM of design comrpomises and you cannot just combine random "numbers" and expect success.
Like when I was racing stock cars,, there were articles all the time, "shave .5 of a second off your laptime by this trick" Heck if you implemented all the tricks outlined in those articles theoretically you would end up running half second laps,, lol and that wont work in the real world. SO remember every design is a system which has been refined by tweaks and small adjustments to make the airframe perform the way the designer wanted. Every change served a purpose and unless you know the interaction and the purpose of each variance of numbers, then yoru really just poking sticks in the dark.

My suggestion is to blatently copy a design 100%, change the wingtips, canopy, and rudder,, but leave the airframe intact..

Matthew Brown · « **Reply #10 on:** June 14, 2016, 08:23:17 AM »

Good points Mark.
Currently since all I have flying is an old slow combat, a 1/2a combat and a slow combat-ish looking design I built for electric power. My current flying consists of launch, maybe one lap to orient with the wind and then I plant my feet and fly out the tank/battery pack then land. I rarely fly laps unless I just want to fly inverted a while.
My goal though is to get a few planes to fly the pattern and learn it. I don't know if I'll compete or not. I've tried RC pattern years ago and found I don't have the talent for real precision flying. I was decent but knew I'd never be "good". I would imagine CL precision aerobatics would have similar results. I do intend to find out though!

Matt

Matthew Brown · « **Reply #11 on:** June 14, 2016, 08:51:21 AM »

I can relate to the stock car comments. I raced Dirt Late Models back through most of the '90s.

Your ideas about altering the fin, wing tips etc is undoubtedly the best bet. I struggle turning what I see in my head into reality. Never really seem to nail what I'm after visually. I've got a Brodak Pathfinder on the way and while it's not exactly what I'm seeing in my head, it will likely be close enough for me and from what I've heard it is a decent flying plane.

Matt

Tim Wescott · « **Reply #12 on:** June 14, 2016, 09:07:11 AM »

Quote from: Basmntdweller on June 14, 2016, 08:23:17 AM

I've tried RC pattern years ago and found I don't have the talent for real precision flying. I was decent but knew I'd never be "good". I would imagine CL precision aerobatics would have similar results. I do intend to find out though!

Matt

So, you're one of the guys that makes Stunt into Combat Guy Old Folks Home?

The key to getting the pattern down is to practice, practice, practice and then practice some more. I found that directed practice works best for me. "Directed practice" means that you go out there with a goal and you meet that goal. It also means that if you can you get yourself a coach, even if it's another pilot at your level. I have a flying buddy who watches my flights and tells me where I'm screwing up, and I do the same for him. Then we brainstorm on how to not make that particular screwup, and fly again.

(And note that sometimes avoiding a screwup can mean changing something that you do quite a bit in advance of the screwup, particularly in a combination maneuver -- in some cases by the time you get to the visible screwup you've already made a pile of smaller errors that pretty much force you into the mistake.)

Howard Rush · « **Reply #13 on:** June 14, 2016, 11:23:08 AM »

A good stunt plane that is trimmed well is very easy to fly. The easiest-to-fly stunter I've flown won the Nats twice, once in a pretty paint scheme, then repainted a few years later to look more ordinary. Here is how I'd pick a stunt plane. Go up I-69 to Muncie the morning of July 23. On one circle there will be five old men flying stunt. Pick whichever of their airplanes tickles your fancy or could tickle it if the wing tip or tail shape is changed a little. After its owner has flown three flights (be sure to wait), ask him where to get drawings, parts, and details for his airplane. He will be happy to help you. Then build one and trim it like this: http://flyinglines.org/walkerstunt.html . There is one alternative: https://grabcad.com/library/max-bee-1 . See the Jan-Feb and March-April copies of Stunt News for details. You can probably get them from PAMPA. I am hopeful that somebody will post how to do that.

Mark Scarborough · « **Reply #14 on:** June 14, 2016, 12:36:07 PM »

Quote from: Howard Rush on June 14, 2016, 11:23:08 AM

A good stunt plane that is trimmed well is very easy to fly. The easiest-to-fly stunter I've flown won the Nats twice, once in a pretty paint scheme, then repainted a few years later to look more ordinary. Here is how I'd pick a stunt plane. Go up I-69 to Muncie the morning of July 23. On one circle there will be five old men flying stunt. Pick whichever of their airplanes tickles your fancy or could tickle it if the wing tip or tail shape is changed a little. After its owner has flown three flights (be sure to wait), ask him where to get drawings, parts, and details for his airplane. He will be happy to help you. Then build one and trim it like this: http://flyinglines.org/walkerstunt.html . There is one alternative: https://grabcad.com/library/max-bee-1 . See the Jan-Feb and March-April copies of Stunt News for details. You can probably get them from PAMPA. I am hopeful that somebody will post how to do that.

Howard, that is absolutly the perfect response,, sheesh, a guy would think you knew something about stunt stuff,,

Tim Wescott · « **Reply #15 on:** June 14, 2016, 01:30:08 PM »

Quote from: Mark Scarborough on June 14, 2016, 12:36:07 PM

Howard, that is absolutly the perfect response,, sheesh, a guy would think you knew something about stunt stuff,,

So, is putting a V-tail on the thing "minor"?

(Do what Howard said. If you can't make it to Muncie, look at the contest results and then check back here. Some of the planes from prior years are kitted.)

Quote from: Basmntdweller on June 14, 2016, 08:51:21 AM

I struggle turning what I see in my head into reality. Never really seem to nail what I'm after visually.

Sketch, mold, carve, repeat. I can usually get close enough to what I want by sketching 3-views, and then finish up with carving on the real thing. But sometimes I miss, so I can understand the frustration.

Randy Powell · « **Reply #16 on:** June 19, 2016, 01:41:08 PM »

Also note that if you go outside excepted parameters in any particular, you will be giving something up somewhere else.

Target · « **Reply #17 on:** June 19, 2016, 07:17:33 PM »

Subscribing since the notification button doesn't seem to work for me...

R,
Chris

Tim Wescott · « **Reply #18 on:** June 19, 2016, 08:29:37 PM »

Quote from: Randy Powell on June 19, 2016, 01:41:08 PM

Also note that if you go outside excepted parameters in any particular, you will be giving something up somewhere else.

Sez "Mr Wild Design"

The problem is knowing which accepted parameters are really important, and which ones can be changed.

Mark Scarborough · « **Reply #19 on:** June 19, 2016, 10:55:52 PM »

Quote from: Tim Wescott on June 19, 2016, 08:29:37 PM

Sez "Mr Wild Design"

The problem is knowing which accepted parameters are really important, and which ones can be changed.

who better to know, I wish I would have been around for Randys High aspect ratio adventure, they fascinate me,,

Randy Powell · « **Reply #20 on:** June 19, 2016, 10:59:58 PM »

Yea, it was adventurous. They sure turned well, but had other problems.

Author Topic: Design generalities (Read 6156 times)

Matthew Brown

Matthew Brown

Matthew Brown

Matthew Brown

Matthew Brown