Aerobatics and Pushers

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etterre

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I still doodle pushers on my napkins every once in a while and I often wonder about how much fun it would be to perform aerobatics. So besides the obvious emergency-exit challenges, are there any other reasons why you wouldn't want to perform aerobatics in a pusher that was designed for the g-loads, had an inverted fuel/oil system, etc? The layout I have in mind would be similar to the yellow plane in the attachment. I'm not thinking about any sort of competition-level stuff, just the sort of fun-level stuff you could do in an RV
 

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Dana

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Probably the biggest issue with acro in a pusher is that they generally have high thrust lines, so pitch changes with thrust would have to be dealt with. Other than that I can't see any major issues for basic aerobatics.

-Dana

The man who would be fully employed should procure a ship or a woman, for no two things produce more trouble" - Plautus 254-184 B.C.
 

Mac790

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The layout I have in mind would be similar to the yellow plane in the attachment.
It's J-1 Don Quixote, Janowki design, do you have plans for that plane?, are you going to build
-top wing (like J-1 Przasniczka/Don Quixote )
-mid wing (like J-2 Polonez someone was selling plans in my country for that plane week ago, end price was 110$ or J-6 Fregata)

btw Canard pushers doing well in aerobatics, you can check my old post on another forum with a couple of movies here http://www.canardzone.com/forum/showpost.php?p=17445&postcount=3

Seb
 

etterre

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It's J-1 Don Quixote, Janowki design, do you have plans for that plane?
I have a paper copy of the J1-B plans. They're second or third generation copies, though.

, are you going to build
-top wing (like J-1 Przasniczka/Don Quixote )
-mid wing (like J-2 Polonez someone was selling plans in my country for that plane week ago, end price was 110$ or J-6 Fregata)
The short answer is that I'm not sure. The longer answer is that, if the plane I build looks like my napkin sketches, I'll probably only be using Janowski's design as "inspiration material." I'm probably going to need two seats and some limited (500 miles in one day) cross country capability...

So an RV would be great if I could bring myself to like them :whistle: Unfortunately, I'm just not a metal guy and I like watching the ground pass by too much to have a wing right in my downward view.

The high wing layout would probably offer less pitch change with power changes, easier fuel flow from wing tanks, and less chance of someone trying to sit on the wing... but a low wing could offer better access to the engine, some protection from sucking stones into the prop, and there might be some structural benefits as well. But I haven't done any of the requisite math yet - maybe I'll be at Duncan's (rtfm) stage some time in the next 2 years or so. :tired:

btw Canard pushers doing well in aerobatics, you can check my old post on another forum with a couple of movies here http://www.canardzone.com/forum/showpost.php?p=17445&postcount=3

Seb
Nice stuff - thanks!
 

djschwartz

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I still doodle pushers on my napkins every once in a while and I often wonder about how much fun it would be to perform aerobatics. So besides the obvious emergency-exit challenges, are there any other reasons why you wouldn't want to perform aerobatics in a pusher that was designed for the g-loads, had an inverted fuel/oil system, etc? The layout I have in mind would be similar to the yellow plane in the attachment. I'm not thinking about any sort of competition-level stuff, just the sort of fun-level stuff you could do in an RV
The small cross sectional area of the fuselage aft of the pod makes achieving adequate structural integrity for aerobatic more difficult. As a result, they are typically heavier have higher drag than conventional designs. When you say "like in an RV" are you thinking of a design with similar power, speed, wing loading, etc to an RV; or, something more like an ultralight as shown in the picture? Most ultralights and near ultralights in the LS category have woefully inadequate performance and control response for even basic aerobatics to be done safely. If you want an RV class of airplane, why not just build one. They are outstanding machines.
 

etterre

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The small cross sectional area of the fuselage aft of the pod makes achieving adequate structural integrity for aerobatic more difficult.
I had not considered that - it would have hit me while I did the structural calcs, though. Thanks - this is the sort of thing I'm looking for in order to decide whether or not aerobatics is worth considering.

When you say "like in an RV" are you thinking of a design with similar power, speed, wing loading, etc to an RV; or, something more like an ultralight as shown in the picture?
The picture was meant merely to explain the layout (taildragger, fixed gear, pusher, normal tail, etc.) As I said above, I doubt that I'm actually going to build a Janowski J1B. The airplane in my head is closer to an RV than an ultralight, but I'm also likely to fall outside of LSA as well (too fast and too heavy). I haven't set hard goals for speed and weight yet - partially because I haven't completely defined the mission profile yet. I'd like to have a little cross-country capability, but it may actually make more sense to have a share in Cessna 180/182 (or bigger) and make "my airplane" into a fun 2-place that isn't meant to go more than 200 miles on a tank of gas (much like Orion's Rohr inspired design). In other words, I'm still daydreaming rather than really designing.

Most ultralights and near ultralights in the LS category have woefully inadequate performance and control response for even basic aerobatics to be done safely. If you want an RV class of airplane, why not just build one. They are outstanding machines.
Mostly agreed... but I know myself well enough to know than an RV wouldn't satisfy me. If I bought an RV kit, I doubt that I'd finish it because I'd feel like I was "settling." If I'm compromising enough than an RV looks good, then why build one? Various models are on Barnstormers all the time. And then, if I'm buying instead of building, why not buy a certified bird? And so on until I start thinking that I might as well rent or join a partnership for the forseeable future.

Nope, various forces in my life (desire for ground visibility, finances, time, etc.) have already pushed me down a plans-built or "design my own" sort of path.
 

rpellicciotti

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I still doodle pushers on my napkins every once in a while and I often wonder about how much fun it would be to perform aerobatics. So besides the obvious emergency-exit challenges, are there any other reasons why you wouldn't want to perform aerobatics in a pusher that was designed for the g-loads, had an inverted fuel/oil system, etc? The layout I have in mind would be similar to the yellow plane in the attachment. I'm not thinking about any sort of competition-level stuff, just the sort of fun-level stuff you could do in an RV
You mean something like the "Ultrabat"? This airplane had the wing, engine and horizontal tail all inline. All carbon fiber. Very nice airplane. I had a chance to fly it a few times. Performed well enough to fly in Sportsman category at IAC contests.
 

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etterre

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You mean something like the "Ultrabat"? This airplane had the wing, engine and horizontal tail all inline. All carbon fiber. Very nice airplane. I had a chance to fly it a few times. Performed well enough to fly in Sportsman category at IAC contests.
Intriguing! So it could be done...:ponder: Sportsman competition is probably an intensity level well above what I was considering. Would you happen to have any links where I could find out some more? A quick search yielded a MSN group... which seemed to have no recent posts... but it did have an email address to request more info.

Thanks!
 

Mac790

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Do you look for plans or kit version? If you are looking for plans version I know about Janowski's designs like J-1 Don Quixote (pic 2-7 some construction details, it's unfinished part of bigger uni project), J-2 Polonez both plans versions wooden construction.

There is also Piuma lightaircraft pic8, again plans-wooden construction.
webpage here PIUMA PROJECT - PIUMA EVOLUZIONE
they have also 2 seats version side by side.

If you are looking for kit version, you might want to check out again Janowski's design like for example J-6 Fregata pic1 (I really like it), but I'm not sure what is the current status of that plane. webpage here J6 Fregata

There are also ready to fly similar designs, but they are rather expensive above 100.000 Euro if I remember correctly. Probably certified, that's why they are soo expensive.

Seb

btw Jake sorry for soo many attachments, I think I should have some kind of monthly limitations. You know like two attachments per month.:)
 

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jprevj

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Wow. Nice. I'm looking for plans only. I've been having a really hard time finding plans for a pusher. I watched a video from the FL Sun and Fun fly in and saw tons of them I just don't have a name to go with the aircraft.

I have always liked the J1-B but have read that, possibly wrongly, it has some yaw stability issues? Also I would prefer to have removable wings.

Thanks for the info! Any other plans/websites would be greatly appreciated.

Thanks,

Joe
 

etterre

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If you are looking for plans version I know about Janowski's designs like J-1 Don Quixote (pic 2-7 some construction details, it's unfinished part of bigger uni project)
Nice!! :) Are you modelling the J1-B in Solidworks for a clas project? If so, what do you intend to do with the results? I know there are folks on the Janowski Yahoo! group who would love to have a reliable set of plans in CAD...
 
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etterre

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Wow. Nice. I'm looking for plans only. I've been having a really hard time finding plans for a pusher. I watched a video from the FL Sun and Fun fly in and saw tons of them I just don't have a name to go with the aircraft.
Yeah, I feel your pain... The problem is that there really aren't many plans available... and then pushers tend to be a little less popular in general. I'd wager that a fair number of the planes you saw on the video were LSAs or "fat ultralights" and the bulk of those are kit aircraft.

One of my favorite kits is the Airaile by RANS:
RANS Aircraft Page

There's also the Challenger:
Challenger - Light Sport, Experimental Amateur-Built, Advanced Ultralight & Part 103 Aircraft

And the CGS hawk
CGS Aviation The Home of the Hawk!

There are lots of others, but I can't think of websites for them... If your primary reason for wanting a plans-built is to keep the cost down, I'd recommend going over to www.Barnstormers.com and doing a search for anything between say $5,000 and $25,000. That should get you a bunch of pictures to look at and some names to go with the pictures. Then do a second search based just on the names of the airplanes you like... you might be able to pick up an unfinished kit or a damaged airframe on barnstormers or craigslist, or even eBay (if you're careful)
 

Mac790

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etterre said:
Are you modelling the J1-B in Solidworks for a clas project? If so, what do you intend to do with the results?
It's actually a bigger project than a class project. It's a part of BA project and some kind of beggining of the MA project.

For the BA, I have to get as many info as possbile about J-1 (I will need it for later project, of course if I decide to carry on), so I have to create 3 models
-in CAD it will let me to get almost exact info about J-1 mass (I can add density properties for each element)
-second model in CAD for flow analysis, model which I have currently pic7 isn't perfect, I have to make a new one in Catia or Rhino, I tried two times in Solidworks but there are always some errors in it, I can't export it sucessfuly into software for meshing geometry for flow analysis.
-stuctural model, I have about a half of it in Femap, but I'll probably make a new one in Ansys, I was on the Ansys12 meeting/presentation 2 days ago and that software is amazing, I'm going for a course in about 3 weeks.

I have 3 months and two weeks before deadline, my tutor said it will be good if I make two models and one analysis (flow or structural), will see at the moment I'm going to make it all.

btw the best about being a student is free access to almost all kind of software:)

pic1 it's Clark Y13 (Norman thanks again for coordinates:) ) J-1 2D airfoil model, made a few weeks ago, far away from being perfect, actualy it's in another Galaxy:gig:

know there are folks on the Janowski Yahoo! group who would love to have a reliable set of plans in CAD
I'm sure about it, but there is one problem with non commercial software you can't make things for others.

Seb
 

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etterre

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Quote:
know there are folks on the Janowski Yahoo! group who would love to have a reliable set of plans in CAD
I'm sure about it, but there is one problem with non commercial software you can't make things for others.
Oh you can make all sorts of cool things... you just can't sell any of it, so you have to give it away - which isn't really fair, given the amount of work that you've put into it.
 

bmcj

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So besides the obvious emergency-exit challenges, are there any other reasons why you wouldn't want to perform aerobatics in a pusher that was designed for the g-loads, had an inverted fuel/oil system, etc?
One thought I had is that large control deflections and g-load induced separation from the wing/tail surfaces might introduce large flow disturbances through the prop giving you a reduction in thrust, noisier/rougher ride, and possible added stress on the prop blades and flange.
 

Cloudsabovenine

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While it is a simple ultralight, the low engine/high tailboom design of the Kolb Ultrastar might be the way to go. It would put the thrust line below the center of lift, perfect for going vertical.
 
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