PBXL Scratch Build
11-26-2003, 09:27 PM
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PBXL Scratch Build
I have been admiring the PBXL that HSRCM Model Airplanes kits out for some time now and finally decided to scratch build one using their FREE plans that are downloadable from their site. Although I must admit that I made several modifications in the plans to suit my taste - all of which I will not go in to now but if anyone is interested I'll be glad to expound on the subject.
Putting this thing together has been tons of fun and actually builds fairly quickly even though all the parts have been cut by hand. Tonight I finally got the framing complete and wanted to share a few photos of this neat li'l foil in the bones. I plan to start covering tomorrow if all goes well and I can persuade my wife and family to let the ol' man play.
The gear that I am planning to install consist of an OS .25FX up front with a 10x4 APC prop. I decided with this kind of power the HiTec 425BB servos would be just about right for the control surfaces and still not have to worry about the additional weight. The color scheme will be Cub Yellow and transparent red. I find this color combination is quite visible - even when it's near dark.
After watching the videos that are on HSRCM's site, I know this thing is gonna be a blast to fly. And the thing I'm hoping for most is that it will be something that I can fly in our club fun flys this next season. I plan on flying the maiden sometime this next week - I'll post the outcome then.
Putting this thing together has been tons of fun and actually builds fairly quickly even though all the parts have been cut by hand. Tonight I finally got the framing complete and wanted to share a few photos of this neat li'l foil in the bones. I plan to start covering tomorrow if all goes well and I can persuade my wife and family to let the ol' man play.
The gear that I am planning to install consist of an OS .25FX up front with a 10x4 APC prop. I decided with this kind of power the HiTec 425BB servos would be just about right for the control surfaces and still not have to worry about the additional weight. The color scheme will be Cub Yellow and transparent red. I find this color combination is quite visible - even when it's near dark.
After watching the videos that are on HSRCM's site, I know this thing is gonna be a blast to fly. And the thing I'm hoping for most is that it will be something that I can fly in our club fun flys this next season. I plan on flying the maiden sometime this next week - I'll post the outcome then.
11-27-2003, 09:37 AM
#2
RE: PBXL Scratch Build
Hey Push Rodz.....awesome looking plane dude!!!!! That looks like blast to fly. A guy who flies at my feild has an old .25 FP and he runs a 10X3 APC prop pulling a home made 3-D plane with a 36" wing span, big fat symetrical wing. With all that drag, the large prop wash area gives him a lot of control and slows the plane down big time.
I would like to see photos or even a movie if you could load one up on the web somewhere. I am getting a new lap top, a Dell with a DVD burner and some nice video editing soft ware. I will be redoing my movies on my RC homepage so they will be larger and more clear. Please keep us updated on your progress, good luck and thanks for sending me the link!!!!
I would like to see photos or even a movie if you could load one up on the web somewhere. I am getting a new lap top, a Dell with a DVD burner and some nice video editing soft ware. I will be redoing my movies on my RC homepage so they will be larger and more clear. Please keep us updated on your progress, good luck and thanks for sending me the link!!!!
11-28-2003, 11:42 PM
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RE: PBXL Scratch Build
Dave - thanks for the compliments.....everything here is on schedule and I should be able to put this puppy up in the next few days. I covered all day Thanksgiving (stopped long enough to pig out) and wrapped up the trim work this morning. Mounted the new engine on the stand today and ran 16 oz. or fuel through 'er - talking about a screamer!!! The .25FX is gonna be perfect for this bird. I'll finish breaking in the engine on the plane.
I hope to get the servos in either tomorrow or Sunday and finish hooking things up. I'll keep ya posted........
Here's a few pics of the finished covering job.........
I hope to get the servos in either tomorrow or Sunday and finish hooking things up. I'll keep ya posted........
Here's a few pics of the finished covering job.........
11-29-2003, 08:50 AM
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RE: PBXL Scratch Build
Hey Bro -
Glad ya like the PBXL - thanks!!! I wished the photos came out a little clearer - hate using the flash - it doesn't give the MonoKote that "just covered" crispy shine. Then again - it may be the photographer....he....he.
Yep - the rudder is fully functional. I will put a pull - pull on it. The rudder servo goes where the fuse is blocked out. This photo shows the rudder a little better.
Actually, the rudder set up is one of the modifications that I made from the original plans. I increased the height 2" to give it a boost in total area for more authority. I also pulled it (and the fuse) aft so the trailing edges of the tail surfaces lined up. By doing this, I also had to modify the shape of the elevons and the tail skid reinforcement. From the photo you can see that the tail skid reinforcement is now "dove tail" shaped. By doing this, it will allow greater throw in the rudder and also clears the throw in the elevons. This will help (in theory) with hoovering. As you know, the rudder is a major input in hoovering......and this is supposed to be an awesome plane for that!!!
This has been a pet project since I got serious about building it. I put the TigerKitten on hold so I could get this one built. I am in search of that "perfect" 3D / Fun Fly plane. Maybe this one is it........we'll see.
Glad ya like the PBXL - thanks!!! I wished the photos came out a little clearer - hate using the flash - it doesn't give the MonoKote that "just covered" crispy shine. Then again - it may be the photographer....he....he.
Yep - the rudder is fully functional. I will put a pull - pull on it. The rudder servo goes where the fuse is blocked out. This photo shows the rudder a little better.
Actually, the rudder set up is one of the modifications that I made from the original plans. I increased the height 2" to give it a boost in total area for more authority. I also pulled it (and the fuse) aft so the trailing edges of the tail surfaces lined up. By doing this, I also had to modify the shape of the elevons and the tail skid reinforcement. From the photo you can see that the tail skid reinforcement is now "dove tail" shaped. By doing this, it will allow greater throw in the rudder and also clears the throw in the elevons. This will help (in theory) with hoovering. As you know, the rudder is a major input in hoovering......and this is supposed to be an awesome plane for that!!!
This has been a pet project since I got serious about building it. I put the TigerKitten on hold so I could get this one built. I am in search of that "perfect" 3D / Fun Fly plane. Maybe this one is it........we'll see.
12-07-2003, 11:01 AM
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Flight Report
I now understand why the plans are FREE!!!
Below are a few pics taken prior to flying the maiden. Looks are veeeeeeery deceiving..........
Below are a few pics taken prior to flying the maiden. Looks are veeeeeeery deceiving..........
12-07-2003, 11:33 PM
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RE: Flight Report
Dave,
Actually when I posted my flight report, I was not too impressed with the way the PBXL flew. I flew the maiden Saturday when a buddy of mine and I loaded up our planes and gear and headed to our club field. The weather conditions were perfect - 50ish degrees, winds 5 mph and very sunny.
To start things off, the gear was too high, which made take offs and landings a bit touchy. As a matter of fact, I had to give up on taking off on the grass and use the paved runway. Next, I had my rates way too low for this bird. Low rates set at 65% and highs on 85%. I adjusted these on the second flight as 85% was still way too low. This thing handled like flying a brick, the response was crappy and the roll rate was zero. I could get a "half roll" with no problem, but the darn thing wouldn't complete the roll to full upright. It reminded me of a turtle on its' back and it wouldn't budge. The only way I could get out of inverted was to either give it up or down elevator. So, needless to say, I flew it at least 2 mistakes high.
Loops were nice and tight. Hovering was not the easiest, and harriers were out of the question. I broke 2 APC's in the process and to make a long story short, I was pretty aggrivated at the whole ordeal. When I left the field I had full intention of removing all my gear and abandoning the plane and chalking up this one as a "bad idea".
I got up this morning, determined to give it one more shot. I bent the gear forward to where it was positioned even with the LE. Of course it brought the height at the front waaaay down but still allows enough prop clearance to keep the 10x5 (I ran out of the 10x4's). This helped tremendously on take offs and landings. I also added about a 1/4 oz. of lead (fishing weight) to the tail skid. Upped the rates to 115% - rudder rates are maxxed at 120% from the beginning but rudder input was never an issue. Between these few changes and the 15 - 20 mph winds that we had today - I have to admit that the PBXL is a hoot to fly.
The roll rate was much better (although still could use some improvement as it is not consistent), hovering was pretty descent and the harriers were excellent. It would slow fly a lot better due to the increased winds and take offs and landings were fairly smooth. I have come to the conclussion that this one flys better in harder winds although is a hand full due to its wing area. Kind of like flying a piece of plywood as every little gust effects it sometimes pretty harshly.
All in all, I am pleased with the PBXL. Its' flight characteristics are unique and I suppose I will have to get used to the way it handles. I think I will add just a bit more area to the elevons with the hope of achieving better elevon response to increase the roll rates. You would think the 4" wide controls would be enough but maybe not. The total wing area is 720 sq. inches and I haven't done the math but the ratio may not be correct or should I say - needs to be adjusted. I may even mix in some rudder coupling first to see if it helps before I modify the elevons.
The OS Max .25FX is perfect for this plane - lots of power - unlimited vertical. It really pulls this bird around, even in the heavier winds. Tomorrows winds are supposed to be around 15 - 25 mph. I'm gonna take 'er out after work for a couple of flights and see if the coupling mix makes any difference - we'll see and keep ya posted.
Actually when I posted my flight report, I was not too impressed with the way the PBXL flew. I flew the maiden Saturday when a buddy of mine and I loaded up our planes and gear and headed to our club field. The weather conditions were perfect - 50ish degrees, winds 5 mph and very sunny.
To start things off, the gear was too high, which made take offs and landings a bit touchy. As a matter of fact, I had to give up on taking off on the grass and use the paved runway. Next, I had my rates way too low for this bird. Low rates set at 65% and highs on 85%. I adjusted these on the second flight as 85% was still way too low. This thing handled like flying a brick, the response was crappy and the roll rate was zero. I could get a "half roll" with no problem, but the darn thing wouldn't complete the roll to full upright. It reminded me of a turtle on its' back and it wouldn't budge. The only way I could get out of inverted was to either give it up or down elevator. So, needless to say, I flew it at least 2 mistakes high.
Loops were nice and tight. Hovering was not the easiest, and harriers were out of the question. I broke 2 APC's in the process and to make a long story short, I was pretty aggrivated at the whole ordeal. When I left the field I had full intention of removing all my gear and abandoning the plane and chalking up this one as a "bad idea".
I got up this morning, determined to give it one more shot. I bent the gear forward to where it was positioned even with the LE. Of course it brought the height at the front waaaay down but still allows enough prop clearance to keep the 10x5 (I ran out of the 10x4's). This helped tremendously on take offs and landings. I also added about a 1/4 oz. of lead (fishing weight) to the tail skid. Upped the rates to 115% - rudder rates are maxxed at 120% from the beginning but rudder input was never an issue. Between these few changes and the 15 - 20 mph winds that we had today - I have to admit that the PBXL is a hoot to fly.
The roll rate was much better (although still could use some improvement as it is not consistent), hovering was pretty descent and the harriers were excellent. It would slow fly a lot better due to the increased winds and take offs and landings were fairly smooth. I have come to the conclussion that this one flys better in harder winds although is a hand full due to its wing area. Kind of like flying a piece of plywood as every little gust effects it sometimes pretty harshly.
All in all, I am pleased with the PBXL. Its' flight characteristics are unique and I suppose I will have to get used to the way it handles. I think I will add just a bit more area to the elevons with the hope of achieving better elevon response to increase the roll rates. You would think the 4" wide controls would be enough but maybe not. The total wing area is 720 sq. inches and I haven't done the math but the ratio may not be correct or should I say - needs to be adjusted. I may even mix in some rudder coupling first to see if it helps before I modify the elevons.
The OS Max .25FX is perfect for this plane - lots of power - unlimited vertical. It really pulls this bird around, even in the heavier winds. Tomorrows winds are supposed to be around 15 - 25 mph. I'm gonna take 'er out after work for a couple of flights and see if the coupling mix makes any difference - we'll see and keep ya posted.
12-08-2003, 01:01 AM
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RE: Flight Report
Push Rodz - I've had some planes that were predisposed to nosing over before they got up to speed on take off. What I found works *most* of the time is having someone hold it and then giving it full throttle prior to release.
Do you plan to post videos of this plane someplace?
Do you plan to post videos of this plane someplace?
12-09-2003, 08:41 AM
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RE: Flight Report
Guys -
The PBXL is getting better and better. I added in about 15% rudder coupling and the roll rate is is lots better. But, speed is necessary to get the quick response. When it falls out of a hover, it has a tendency to fall on its' back and getting it back to upright is a challenge. I think I'll add a bit more weight to the tail skid to see if that helps in hovering. I sat down last night and made the 1 1/2" elevon extensions that I can add to the control surfaces, but I'm hesitant to retro fit them on because I don't want to develope a flutter problem. I'll toss this issue around.
The take offs and landings are no longer an issue since I bent the gear forward. Keeping it low and slow is no longer a problem - for what ever reason. I think it just needs to have a little "breeze" to fly in to. All in all, the PBXL is beginning to be one of my favorite planes to fly. I think with a little more adjusting (mostly on my part) it will work fine for our club fun flys.
Paul, I don't have the means (at this point) to take any movie shots although I will ask around at the field to see if someone there has the capabilities. I would like to have some movies for myself because this bird is a hoot to see fly. It kinda looks like a little roadster in the sky.
Dave, how did the Speedy Bee do? And on floats???? This sounds cool dude - post some pics!
The PBXL is getting better and better. I added in about 15% rudder coupling and the roll rate is is lots better. But, speed is necessary to get the quick response. When it falls out of a hover, it has a tendency to fall on its' back and getting it back to upright is a challenge. I think I'll add a bit more weight to the tail skid to see if that helps in hovering. I sat down last night and made the 1 1/2" elevon extensions that I can add to the control surfaces, but I'm hesitant to retro fit them on because I don't want to develope a flutter problem. I'll toss this issue around.
The take offs and landings are no longer an issue since I bent the gear forward. Keeping it low and slow is no longer a problem - for what ever reason. I think it just needs to have a little "breeze" to fly in to. All in all, the PBXL is beginning to be one of my favorite planes to fly. I think with a little more adjusting (mostly on my part) it will work fine for our club fun flys.
Paul, I don't have the means (at this point) to take any movie shots although I will ask around at the field to see if someone there has the capabilities. I would like to have some movies for myself because this bird is a hoot to see fly. It kinda looks like a little roadster in the sky.
Dave, how did the Speedy Bee do? And on floats???? This sounds cool dude - post some pics!
12-11-2003, 03:32 PM
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RE: Flight Report
Yeah - that's the delima that I'm facing - speed. According to Kevin, this plane is not supposed to like speed however, mine loves it. Depending on the maneuver, it performs best at a little quicker speed. Hoovering and such of course doesn't require much but the neat thing about the PBXL is that it is very versatile. And because I fly according to the mood I'm in at the moment I like the idea of not having to worry about flutter which, right now I don't.
I'm in the process of building a smaller version with some "extreme" changes and modifications. One change is that I have incorporated the extended elevons (proportionately to its' big brother) and am going to test the idea (as well as several others) on it. I'm hoping that this will resolve a couple of issues. The first - will it give greater control authority at lower speeds and second, will flutter be an issue at higher speeds. If this works out the way I hope, then I will go ahead and install the retro fits on the original.
I'm pretty excited about the smaller version. I plan to mount an OS Max .15LA on it with HiTec HS-81 servos. It is framing up super light, and even though the .15 will most likely be way more power than it really needs, I expect it will be an awesome 3-D/fun flyer! I'll post some photos as soon as I get all the framing complete.
I'm in the process of building a smaller version with some "extreme" changes and modifications. One change is that I have incorporated the extended elevons (proportionately to its' big brother) and am going to test the idea (as well as several others) on it. I'm hoping that this will resolve a couple of issues. The first - will it give greater control authority at lower speeds and second, will flutter be an issue at higher speeds. If this works out the way I hope, then I will go ahead and install the retro fits on the original.
I'm pretty excited about the smaller version. I plan to mount an OS Max .15LA on it with HiTec HS-81 servos. It is framing up super light, and even though the .15 will most likely be way more power than it really needs, I expect it will be an awesome 3-D/fun flyer! I'll post some photos as soon as I get all the framing complete.
