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Pusher AP plane build thread

Old 11-27-2005, 08:48 PM
  #26  
W4UAV
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Default RE: Pusher AP plane build thread

I did get off on a tangent there, lets keep it to the build! Dan, would you recommend maybe a pitts muffler and moving the engine a little above the thrustline? Get the head into the air rushing over the wing and cool. If he used the standard pitts muffler and mounted the engine upright the pitts' pipes would be out to the left side of the plane, they are usually too long so the builder can cut them down to fit near a cowl setup.
Mike R.
Old 11-27-2005, 09:24 PM
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Default RE: Pusher AP plane build thread

I don't know. I mounted my engine inverted to keep the firewall small while getting the prop shaft as high up as I could. I don't have the engine cowled in at all. I think there is more than enough airflow to run this way. The engine isn't in the prop wash but at an idle on the ground and getting run up for take off gets the plane in motion. A tightly cowled engine in a tractor configuration is at greater risk. I think it will be OK that way. It will also allow the carb to stay lower down the firewall so it's closer to the fuel pickup level in the tank. One can always put an engine mount with longer rails on to push the engine and muffler farther away from the fire wall for clearance. If Skycam41 has adequate prop clearance for his known runways it may not be an issue. I've seen a lot of planes with props close to the ground that aren't set up in these twin tail boom pushers like ours. It's common to see grass stains and nicks from rocks on the props so I don't want to sound too paranoid about the clearance. Low wing tail draggers bust props commonly on bad landings. I think I just got jumpy because I was flying off gravel with Zinger 18 inch wooden pusher props. A rock in the right place and I was out a 25.00 prop just like that. That 2 cid gas Fuji I’m using really vacuums loose debris on a take off run. It moves one heckuva lot of air.

I don’t see any reason he wouldn’t want to shift the thrust line upward above the aircraft centerline. Randall1959 does that to great extent by putting the motors and engines on his planes up high on pylons etc. I don’t like to move too far away like that just because of induced drag in that style. I’m not suggesting that’s a bad thing mind you. In a slow flying stable AP plane that’s a manageable quality. My application just works better with faster flight and more efficient travel through air. I conserve fuel that way too.

Dan
Old 11-27-2005, 09:34 PM
  #28  
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Default RE: Pusher AP plane build thread

My glow AP plane is nearly overpowered so that's mainly how I get away with it. I also stretched the wing out on both ends for more lift. Drag is not a critical issue on a big floater plane and will also help it fly more slowly in some cases.
My plane weighs 9 lb fully loaded, but with a 72" wing it lands at little more than walking speed, even in light breezes. I've dead sticked it a couple of times to see how it glides and even being as heavy as it was, it still glided for quite a long time and came in nice and slow.
My glow ap plane actually flies a lot like it did when it was a simple trainer. The ground handling was a bit tricky until I figured out that my configuration needs "up" thrust instead of down.
If Skycam were to elevate his motor, on a pusher it would also need some "up" thrust so as to not want to push the nose over under power.
Right now I'm happy with my glow plane so now my attention is focused on building a couple of good electric ap planes. Much more people friendly and easier to transport.
But for shots out in the country it will most definately be the slimer. Say what ya want, but a slimer stays in the air longer, less power issues, and will allow you much more in lifting power.
Old 11-27-2005, 09:55 PM
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Default RE: Pusher AP plane build thread

Agreed Randall1959. And I want to emphasize I wasn't talking down the Engine on a pylon. It's the best way to go in many cases. There are even pusher planes with single tail booms that have the pusher engine up on a pylon for clearance. In this particular build though, the design criteria is different. I also agree with your assessment about electric and fuel burning planes. I can take my gasser out in the early morning and although I have to land once an hour for gasoline, I can fly all day long without having to charge anything. But, I'm building an electric now to fill in some gaps and fly in different settings.

Dan
Old 11-28-2005, 12:42 AM
  #30  
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Default RE: Pusher AP plane build thread

Here is a picture of the enigne being held in place. My personal feeling is that it will be OK but that is just my thought, not based on fact...lol. I am leaning towards an upright muffler as they are called so that the exhaust stack comes off the side of the engine and points straight down which would be very nice for helping to keep the slime off the plane and would not be a big chunk of metal in the air stream. As always, I am open to suggestions and opinions

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Old 11-28-2005, 12:49 AM
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Default RE: Pusher AP plane build thread

Boy that's a good looking engine. I think your idea sounds good.

Dan
Old 11-28-2005, 01:12 AM
  #32  
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Default RE: Pusher AP plane build thread

Thanks Dan, I too really l ike the powder coating on the Irvine, looks "smart." Well it's turn in time for this chap...g'nite all.
Old 12-01-2005, 02:31 PM
  #33  
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Default RE: Pusher AP plane build thread

Looks like I have the muffler problem solved. Bisson mufflers up here in the frozen white north are goign to custom make an upright style muffler which will bolt right onto the motor and have the exhaust stack pointing down. I am still waiting for the wing kit to arrive [:@] Seeing as I still have the old plans for an LT40 wing I will figure out the boom mounting and get to work on that.
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Old 12-01-2005, 07:10 PM
  #34  
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Default RE: Pusher AP plane build thread

Mike, they also make spacers to extend the muffler from the engine, you might try one of these if it appears the muffler is going to be too close to where you want it, and they usually come with longer bolts. I saw one at the LHS today.
Heres the one I saw, to give you an idea of what I mean, gotta find one for your engine specs:
http://www2.towerhobbies.com/cgi-bin...?&I=LXD638&P=0

Just a tip!

Mike R.
Old 12-01-2005, 07:15 PM
  #35  
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Default RE: Pusher AP plane build thread

Thanks Mike...I sent the same pic I posted to BCM and he was going to make the header long enough to clear the mount but I may still want to use a spacer. I like the idea of the muffler pointing straight down...less crap getting on the plane
Old 12-01-2005, 09:31 PM
  #36  
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Default RE: Pusher AP plane build thread

wow that's nice, looks like some work...
Old 12-02-2005, 01:33 AM
  #37  
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Default RE: Pusher AP plane build thread

I know you weren't talking down on the pylon idea. I was just expanding on the why and how of it all. I too, have built two different electrics for those times when the glow plane is hindered due to space and safety concerns.
There is a lot of drag in my setup but I've also found that drag will work for you if you do some careful planning. When I first set up my glow ap plane it had a stock wing and was much much too fast to be practical. That's when I hit upon the idea of extending the wing (more drag and more lift) and adding wingtip droops.
That's the great thing about this hobby is that there are so very many ways to skin the proverbial cat.
Old 12-03-2005, 11:15 AM
  #38  
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Default RE: Pusher AP plane build thread

OK gang....thinking caps on all. Method of mounting the camera is the subject. The two requirements are A) Being able to tilt the camera through a small range and B) Elliminating as much vibration as possible. Open for suggestions, drawings etc.....
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Old 12-03-2005, 02:48 PM
  #39  
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Default RE: Pusher AP plane build thread

It seems to me that a box inside a box would be one way to go. The outer box can be built so that in the center of one end there is a servo set up to drive the tilt. The opposite end should have a free moving pivot. That box should then have room for some well fit, but not compressed, latex foam. You'll have higher frequency and lower amplitude than 4 stroke or gasoline engines. That means it will be easier to dampen than lower frequency vibration. Keeping a means to put small amounts or strip or pads of foam and keep them in place without permanently fixing them inside is a good idea. That way you can swap out the foam as it ages and loses it's damping properties. (Gooshyness I think it's called ) Anyhow, the camera then can fit inside of a more custom box that holds it tight in the right places but that box fits inside the bigger box with the foam pads in there. The term box is just used for descriptive purposes. A light framework will do.

The more foam you use, or the more you compress it, the less it will dampen for you. Isolating the foam to the four corners or some semblance thereof should net you good results.

Dan
Old 12-03-2005, 03:03 PM
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Default RE: Pusher AP plane build thread

I should also note, and I think we talked about this some off site, but I learned to approach vibration dampening with more of a fluid dynamics thought process. Thats when it finally came together for me. Standard foam rubber does not dampen well. It's to rigid or springy. It lacks visco elastic properties. In this case you want something that won't bounce back into shape as fast as foam. But it can't be like the memory foam used in beds these days or Stretch Armstrong toys. That's fluid but with a very slow rebound. The hobby source latex foam has excellent damping properties but you still have to use it right. It can't be packed tight or it can't rebound inside of it's containment. But it can't have space around it either or there will be room to bounce inside the containment.

The lighter your camera the lower the mass and resultant inertia. If it has low mass it can't compress much foam so you have to be able to add or remove some to "tune" the amount of dampening provided. You should have no trouble with care in the setup to get pretty much all clear pictures.

Dan
Old 12-03-2005, 03:38 PM
  #41  
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Default RE: Pusher AP plane build thread

Great info Dan, thanks. Are you talking about the standard receiver type of latex foam from Hobbico?[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXL431&P=M]This[/link]
Old 12-03-2005, 04:11 PM
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Default RE: Pusher AP plane build thread

I think thats the same stuff. I have a bunch I bought up a year ago that I've been using. I have some still in the package. It has smooth surfaces on the outside. I think I've seen some that was pretty porous. Same material but the open cell stuff is more apt to crumble if it slides against surfaces. Whan I get home from work I'll check the brand and see if there's a pn on the packages I have. I imagine it's all the same core material. I'll post it back here for the lurkurs.

Dan
Old 12-03-2005, 05:03 PM
  #43  
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Default RE: Pusher AP plane build thread

Hobbico is the one you're wanting Mike. It's white and really soft and springy. I used 1/2" bonded between two sheets of ply like a sandwich. Then there's the same stuff between my camera and it's mount and even the washer on the bolt that holds the camera. My camera isn't light though. It weighs 8 oz with servo.
The trick is to not try to have a mount that packs it down too tightly. That sort of defeats the idea.
Old 12-03-2005, 05:05 PM
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Default RE: Pusher AP plane build thread

That is the same material. I have the Hobbico Manufacturer pn HCAQ1000 though. It's only 1/4 inch thick. http://www2.towerhobbies.com/cgi-bin...=++&search3=Go

Dan
Old 12-04-2005, 12:18 AM
  #45  
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Default RE: Pusher AP plane build thread

More progress on the fuselage today, installing the throttle and nose wheel servo's. I partially sheeted the inside of the fuse where the wing mounts with 1/8 lite ply and 1/8 balsa. I plan on installing a bolt on wing so needed a good strong anchor point for the nylon bolt blocks plus I wanted to double the thickness of the wing saddle...it is way more rigid now! The bottom of the fuse I sheeted with 1/16 balsa. I think I will leave the fuse sides open as it is pretty strong. The top of the fuse will have 2 screw on lite ply "hatches" with the "Camera Bay" having a lite ply hinging lid with a thin plexi glass "window." I have not decided on a camera mounting set up yet but will most likely build it so the camera can be facing port or starboard and again with a plexi glass window so I can see the camera LCD monitor....so its not in play back mode...haha, don't laugh I've done that more than once
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Old 12-09-2005, 10:40 PM
  #46  
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Default RE: Pusher AP plane build thread

Not too much going on as I am still waiting for the wing kit etc [&o] but oh well winter is long here so no sense getting it all built in the first few weeks.

Here is a picture of the upper section of the fuse which will house the A/V TX and other equipment. I decided to go with a thin plexiglass lid so I could see what was going on inside and if adjustments need to be made it will be very simple to get access to.
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Old 12-10-2005, 07:11 AM
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Default RE: Pusher AP plane build thread

I like!! Thats very innovative, looks like your AP shp will be like Dan's, very clean and neat, I really like his Pegasus for the way he set things up. I try to be like that, my impatience usually takes over though, I end up saying, "come on, get it finished, get it in the air!"
Coming along nicely, Mike!

Mike R.
Old 12-10-2005, 09:53 AM
  #48  
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Default RE: Pusher AP plane build thread

Gee, I keep trying to make things too complicated..speaking of the camera mount here. I found that my camera "holder" from my Nikon 3700 fits just as well for the Panasonic FX9..duuh Some rubbery foam with some little wedge shapes will give me the tilt I need (don't need to change tilt in flight). I lite ply hatch with a peeky hole for the lens and I am set.
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Old 12-10-2005, 09:19 PM
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Default RE: Pusher AP plane build thread

That's going to be a really nice platform Skycam. Man I'd think about what we talked about with the electric motor with better props.
Old 12-10-2005, 09:33 PM
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Default RE: Pusher AP plane build thread

Very nice Skycam41. Very nice.

Dan

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