Pitts Model 12
10-14-2003, 08:14 PM
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Pitts Model 12
My 25% Pitts Model 12 is finally finished and ready to fly. Attached (I hope) is a pic taken by my good friend Bob who is a whiz with a camera.
The model is scratch-built, has 66" top span, 63" bottom span, weighs 16 lbs, and is powered by a Moki 2.10. The finish is Ceconite and dope, just like the original. If the weather holds it will get its first flight later this week.
The model is scratch-built, has 66" top span, 63" bottom span, weighs 16 lbs, and is powered by a Moki 2.10. The finish is Ceconite and dope, just like the original. If the weather holds it will get its first flight later this week.
10-14-2003, 08:37 PM
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RE: Pitts Model 12
[X(] WOW that is gorgeous!!! Good luck on the first flight - by the looks I imagine it will go great. Are you going to offer plans, or is she just a "one of"?
10-14-2003, 09:32 PM
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RE: Pitts Model 12
The canopy is cut down from a Dave Patrick Extra 330L replacement canopy. I think I ended up using about 1/3 of the original canopy!
The cowl is homegrown of balsa and fiberglass. I originally did the cowl in all fiberglass (created a plug, then made female molds - a ton of work) but it turned out just too heavy. My skills with fiberglass need some work, I guess. I ended up using only the fiberglass nose piece with the rest being balsa and light ply. The finished cowl weighs eight ounces. It reaches all the way back to just ahead of the front wing cabane strut.
The cowl is homegrown of balsa and fiberglass. I originally did the cowl in all fiberglass (created a plug, then made female molds - a ton of work) but it turned out just too heavy. My skills with fiberglass need some work, I guess. I ended up using only the fiberglass nose piece with the rest being balsa and light ply. The finished cowl weighs eight ounces. It reaches all the way back to just ahead of the front wing cabane strut.
10-14-2003, 09:39 PM
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RE: Pitts Model 12
Right now it's just a "one of". During the construction I realized ways to simplify and lighten the construction on the next one. I think I can shave at least 2 - 3 lbs off the finished weight and still be reasonably strong. We'll see what the future holds as far as offering plans or a kit ...
10-15-2003, 10:07 AM
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RE: Pitts Model 12
As a scratch builder you peaked my curiosity. Your weight sounds just about right for the size plane you built. Other than a lighter cowl, how would you save 2 or 3 lbs? Thats a bunch of weight.
tonyc
tonyc
10-15-2003, 04:14 PM
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RE: Pitts Model 12
Several things done differently will save some weight. First, the bottom wing uses a plug-in wing. The wing tube (aluminum) , it's sleeve (phenolic), and the extra structure to support it both in the fuse and the wing add up. I believe I can save 10 to 16 oz. just going to a single piece wing. The fuselage structure is fairly complicated, using a crutch and formers, a common way of building a round fuse. All the internal crutch structure behind the wing really doesn't add all that much in strength (it's light-ply and balsa) and can be eliminated or at least reduced to a balsa space-frame design. The wings themselves are probably overbuilt, I think. Less and lighter wood will reduce weight some. Composite gear would also help - those long-legged aluminum struts add up.
All in all, a lighter structure (target weight 13 to 13.5 lbs rtf) means a smaller and lighter engine.
The weight really isn't that bad now. At 16 lbs dry, it comes out to about 28 oz/ sq. ft. (~1340 sq. in) which is a fairly light loading. The PROOF though will be in the flying! If the weather holds Thursday afternoon will be it's maiden flight.
How 'bout a 29% scale version at the same weight (16 lbs)?
All in all, a lighter structure (target weight 13 to 13.5 lbs rtf) means a smaller and lighter engine.
The weight really isn't that bad now. At 16 lbs dry, it comes out to about 28 oz/ sq. ft. (~1340 sq. in) which is a fairly light loading. The PROOF though will be in the flying! If the weather holds Thursday afternoon will be it's maiden flight.
How 'bout a 29% scale version at the same weight (16 lbs)?
10-15-2003, 04:25 PM
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RE: Pitts Model 12
I have to give credit where credit is due. I bought Bob's plans set and drooled over them for a month or so. What a beautiful set of plans on first-class vellum! The cost though, to build and power the 35% version was just prohibitive for my budget. The more I looked at Bob's plans the more I realized that his design would be a good starting point for a smaller version. I spent about six weeks of nights and weekends doing the CAD drawings for the 25% version while looking over my shoulder at Bob's plans for guidance and inspiration.
10-15-2003, 05:30 PM
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RE: Pitts Model 12
Can you please tell/show me how cabanes are attached? I'm building and similer sized round engine bipe based on the Model 12, and have yet to find a light weight, good looking attachment method. I was going to use 5/8" dowels, but I'm still not sure about it. You can e-mail me at [email protected]. Thanks, Jordan
10-16-2003, 06:04 PM
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RE: Pitts Model 12
Another thing I like (I really like this plane!!) is the way you payed homage to the original scheme. That scheme might be done to death on S1's and S2's, but seeing it on the 12 helps to tie the old and new together. One look, and it says "Pitts", but with the radial cowl and square tips to let you know this ain't your daddy's Pitts!!
10-16-2003, 06:06 PM
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RE: Pitts Model 12
Well, the Pitts made its first flight this afternoon. The weather was near 'bout perfect with just a slight breeze and 72 deg. Clear blue sky and the grass at our field was freshly cut.
I took the wheel pants off for the first flights as that long landing gear had me concerned a bit about ground handling. Sure enough, first takeoff attempt I wasn't ready on the elevator and it nosed over when I came up on full power.[:@] Just broke the prop so we cleaned it up, replace the prop and were ready to go again.
This time I came up a little slower on the power and held some back pressure, not letting the tail rise quite as much this time. The Pitts accelerated straight and true down the runway with just a touch of right rudder. After about 60 feet it lifted off pretty as you please and accelerated rapidly, climbing nicely with still just a bit of back pressure. I flew a couple of laps around the field and only needed 2 clicks of down, 2 clicks left ail., and 1 click of right rudder (and I probably don't need that).
It's very responsive and the rolls are really nice - straight and fast with 4 ailerons. Didn't do much in the way of aerobatics yet 'cause I wanted to see what the slow-speed flight was gonna be like. Well, it flies slow like a big Ugly Stick. I slowly pulled the nose up with the power on and it just hung there. Rudder becomes more effective than ailerons at that point but it doesn't seem to have any tendency to drop a wing.
Did some split S's and loops. The short wings and big prop means it's a rudder airplane. When you get slow and apply power it will accelerate quickly but you have to add rudder as needed.
Landing was uneventful and I made a fairly smooth three-point the first time with just a tad of bounce from that long gear.
All-in-all I'm very pleased with The Pitts Model 12's flight performance and hope to get some more flights on it this weekend.
I took the wheel pants off for the first flights as that long landing gear had me concerned a bit about ground handling. Sure enough, first takeoff attempt I wasn't ready on the elevator and it nosed over when I came up on full power.[:@] Just broke the prop so we cleaned it up, replace the prop and were ready to go again.
This time I came up a little slower on the power and held some back pressure, not letting the tail rise quite as much this time. The Pitts accelerated straight and true down the runway with just a touch of right rudder. After about 60 feet it lifted off pretty as you please and accelerated rapidly, climbing nicely with still just a bit of back pressure. I flew a couple of laps around the field and only needed 2 clicks of down, 2 clicks left ail., and 1 click of right rudder (and I probably don't need that).
It's very responsive and the rolls are really nice - straight and fast with 4 ailerons. Didn't do much in the way of aerobatics yet 'cause I wanted to see what the slow-speed flight was gonna be like. Well, it flies slow like a big Ugly Stick. I slowly pulled the nose up with the power on and it just hung there. Rudder becomes more effective than ailerons at that point but it doesn't seem to have any tendency to drop a wing.
Did some split S's and loops. The short wings and big prop means it's a rudder airplane. When you get slow and apply power it will accelerate quickly but you have to add rudder as needed.
Landing was uneventful and I made a fairly smooth three-point the first time with just a tad of bounce from that long gear.
All-in-all I'm very pleased with The Pitts Model 12's flight performance and hope to get some more flights on it this weekend.
10-16-2003, 06:16 PM
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RE: Pitts Model 12
Thanks, ChuckAuger...
I looked at pix of every Model 12 that's been built (or at least there are pictures of) and I like that scheme the best. It's more or less the N212DK (Dick Krause) Model 12. Most of other M12's have scallops and are purple/yellow or yellow/blue. There's one, though, that really looks cool. It's scallops but it's purple over black with white pinstripes. It's striking but visibility might be a problem as a model.
I looked at pix of every Model 12 that's been built (or at least there are pictures of) and I like that scheme the best. It's more or less the N212DK (Dick Krause) Model 12. Most of other M12's have scallops and are purple/yellow or yellow/blue. There's one, though, that really looks cool. It's scallops but it's purple over black with white pinstripes. It's striking but visibility might be a problem as a model.
10-16-2003, 07:18 PM
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RE: Pitts Model 12
Beautiful airplane and very nice work. Congratulation on the maiden flight. It's really a beauty and I love the Pitts. Any pictures with the cowling off and inside the fuse at the wing saddle? Would love to see more. Interested in the brackets you used for the interplane struts. Did you make them? If sou would like to know from what material and how you did it. I am assembling a G.P. Pitts and this is a weak area in the ARF kit. The Cabbane also has a history, but think G.P. has resolved this issue with hard wood mounts. Really like the canopy. Again, congratulations on a successful project and maiden flight.
10-17-2003, 08:16 AM
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RE: Pitts Model 12
rfw1953...
If I understand what you're asking, the interplane struts are attached to 1/8" ply partial ribs that have a 1/2" by 2.5" long tab that the strut attaches to, top and bottom. The tab is recessed into the strut and all you see externally are the four socket-head screws.
I may be able to get some close-up shots done this weekend of the various parts that may help explain things better. If I can talk my buddy Bob with the camera into taking the pix I'll post 'em here.
Attached is an image of the rib I'm talking about.
If I understand what you're asking, the interplane struts are attached to 1/8" ply partial ribs that have a 1/2" by 2.5" long tab that the strut attaches to, top and bottom. The tab is recessed into the strut and all you see externally are the four socket-head screws.
I may be able to get some close-up shots done this weekend of the various parts that may help explain things better. If I can talk my buddy Bob with the camera into taking the pix I'll post 'em here.
Attached is an image of the rib I'm talking about.
10-17-2003, 06:29 PM
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RE: Pitts Model 12
Curt, thanks for the reply. Wow, thats a solid and very neat solution, but won't work on the pitts ARF. As you may alreay know, G.P uses brackets that mount on the wing tops held in place with hard points built into the wing. Not as neat nor nearly as stong, but with the proper brackets still functional. The problem with the stock brackets is that they have been known to fail. Just one of the those things I hope to resolve before mounting. I understand G.P has an updated bracket coming, but not available to date.
Thanks again for the reply and looking forward to seeing any new pictures posted. Nice work!
Thanks again for the reply and looking forward to seeing any new pictures posted. Nice work!
10-18-2003, 05:26 PM
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RE: Pitts Model 12
rfw1953...
Ah, so. I hadn't really looked at how the struts attached on the ARF Pitts but that makes sense from an ARF manufacturing standpoint. That's a lot easier and simpler to build than how I did it.
To get the internal ribs to line up properly on my Model 12, the strut ribs are not glued in solid when the wings are built. They're left loose and only the top or bottom LE sheeting is installed, enough to make the wing rigid. After the fuselage is built and has the wing attachment structure complete, the partially completed wings are installed. I cut a piece of cheap 1/4" ply as an alignment jig to go between the wings then clamped the strut ribs to it. The ribs were then glued into place and align perfectly when the model is finished and the struts are installed. The struts and attachments are very strong and add rigidity to the entire wing assembly. That type of set-up would be a bear for an ARF manufacturer - too much labor!
Ah, so. I hadn't really looked at how the struts attached on the ARF Pitts but that makes sense from an ARF manufacturing standpoint. That's a lot easier and simpler to build than how I did it.
To get the internal ribs to line up properly on my Model 12, the strut ribs are not glued in solid when the wings are built. They're left loose and only the top or bottom LE sheeting is installed, enough to make the wing rigid. After the fuselage is built and has the wing attachment structure complete, the partially completed wings are installed. I cut a piece of cheap 1/4" ply as an alignment jig to go between the wings then clamped the strut ribs to it. The ribs were then glued into place and align perfectly when the model is finished and the struts are installed. The struts and attachments are very strong and add rigidity to the entire wing assembly. That type of set-up would be a bear for an ARF manufacturer - too much labor!