4*120 Biplane Kit Bash
02-27-2008, 11:53 PM
#1
4*120 Biplane Kit Bash
Has anyone ever thought about buying a extra wing kit for the 4*120 and bashing the kit into a bipe?
I built a 4*120 a couple years ago and ended up selling it. I regret it. Wish I'd kept it. They fly so nice.
I was planning to build the kit again, so I bought a wing kit with the intention of scratching the fuse and formers from my old plans. I just LOVE a good kit bash and got to thinking about using that spare wing kit to turn this into a good size bipe.
I think I'd want to widen the fuse by a couple inches and maybe stretch it out to about 70" in length. In stock form, the kit is only about 4" wide inside. It's a royal PITA to get your hands inside there. I'm thinking it wouldn't be that hard to widen the fuse to 6" all the way to the back of the wing saddle. All I'd have to do is widen my fuse formers by 2". No big deal if I'm planning to scratch build the fuse anyway.
The 81" wing is really hard to fit in my Nissan pickup, so I was thinking about clipping the wings down to about 72". It would still have a ton of wing area. If you knock each wing down to 72", you'd end up with about 1071sq.in. Now add the top wing and you'll have 2142 sq.in.
I think I'd probably go up to a 50cc engine at that point. This plane will probably end up in the 16-18 pound range. 50cc sounds about right for aggressive sport power at my altitude.
Any thoughts or comments?
I built a 4*120 a couple years ago and ended up selling it. I regret it. Wish I'd kept it. They fly so nice.
I was planning to build the kit again, so I bought a wing kit with the intention of scratching the fuse and formers from my old plans. I just LOVE a good kit bash and got to thinking about using that spare wing kit to turn this into a good size bipe.
I think I'd want to widen the fuse by a couple inches and maybe stretch it out to about 70" in length. In stock form, the kit is only about 4" wide inside. It's a royal PITA to get your hands inside there. I'm thinking it wouldn't be that hard to widen the fuse to 6" all the way to the back of the wing saddle. All I'd have to do is widen my fuse formers by 2". No big deal if I'm planning to scratch build the fuse anyway.
The 81" wing is really hard to fit in my Nissan pickup, so I was thinking about clipping the wings down to about 72". It would still have a ton of wing area. If you knock each wing down to 72", you'd end up with about 1071sq.in. Now add the top wing and you'll have 2142 sq.in.
I think I'd probably go up to a 50cc engine at that point. This plane will probably end up in the 16-18 pound range. 50cc sounds about right for aggressive sport power at my altitude.
Any thoughts or comments?
02-28-2008, 02:19 AM
#2
Senior Member
RE: 4*120 Biplane Kit Bash?
what about hog bipe?
the extra wing might change the CG of the four star....
the CG of the four star location is part of what makes it fly so well.... no?
the extra wing might change the CG of the four star....
the CG of the four star location is part of what makes it fly so well.... no?
02-28-2008, 10:34 AM
#3
RE: 4*120 Biplane Kit Bash?
Changing the CG is just a simple math calculation. No big deal. You simply combine the cord of both wings and go back 25%--30% on the forward wing to balance the plane. There are some basic ratios in aircraft design that should be followed. Thats why I think it would be a good idea to stretch the tail out a bit.
The more I think about it, the more I want to do it.
I'd have to put some hardwood blocks in the wings for cabane attachment. There would also need to be a hard mount in the nose somewhere for the center wing support. None of that is extremely difficult.
The more I think about it, the more I want to do it.
I'd have to put some hardwood blocks in the wings for cabane attachment. There would also need to be a hard mount in the nose somewhere for the center wing support. None of that is extremely difficult.
02-28-2008, 11:12 AM
#4
Senior Member
RE: 4*120 Biplane Kit Bash?
A rule of thumb for bipe bashing a mono wing is to make the wings 1/3 smaller than original. This includes chord, thickness and wingspan. A 60" mono wing would use two 40" wings for a bipe bash.
02-28-2008, 10:30 PM
#6
RE: 4*120 Biplane Kit Bash?
I couldn't do a project like this without documenting it all. I'm not sure how many of you saw my 4*120 build thread from 2005. I really enjoyed doing that thread and having people follow along with it. Several other guys were building the same plane and contributed great information to the thread.
I've been talking with my best flying buddy. He thinks it will not fly very good with a semi-symmetrical wing. I have my doubts too.
All of the 4* designs fly very well. We discussed doing some experiments with the 4*40 first. One of the things we talked about was to put the top wing on upside down. Then, when you fly inverted, it's all the same. I would need to build my outer cabanes and inter struts with an adjustable bolt so that I could adjust the incidence between flights. We came up with a simple but effective design for this. I could mount the top wing normally--or upside down--and still have complete control over the incidence with a couple turns of a bolt. Would take all of 2 minutes to make those adjustments at the field.
Using the 4*40 as a design platform would certainly be cheaper than the 120. But, I have the wing kit for the 120 already, and I have the plans for the 120. I've got access to power tools (band saw, drill press, scroll saw, disk sander etc...) so scratching the fuse is really no big deal.
Does anybody have any comments on using semi-symmetrical wings on a bipe like this? How do you think it will fly.
How do you think it would effect the flying if that top wing was built upside down, so the flatter part of the wing was on top when flying? It's not something that I WANT to do. Just wondering if it would give the plane a more neutral feel.
Do other bipes have semi-symmetrical wings? Hog Bipe? Balsa USA Pheaton? GP Stearman? Do they all have fully symmetrical wings? Semi-symmetrical?
What are the disadvantages (if any) of going forward and just using the stock airfoil from the 120? It is going to need more negative incidence on the top wing or would the standard -1.0 up to -1.5 degrees be enough?
These are all design considerations that have just hit me. I'm REALLY concerned about the wings now. Don't want to build a plane that wants to climb all the time and takes 1/2 stick to fly inverted.
I've been talking with my best flying buddy. He thinks it will not fly very good with a semi-symmetrical wing. I have my doubts too.
All of the 4* designs fly very well. We discussed doing some experiments with the 4*40 first. One of the things we talked about was to put the top wing on upside down. Then, when you fly inverted, it's all the same. I would need to build my outer cabanes and inter struts with an adjustable bolt so that I could adjust the incidence between flights. We came up with a simple but effective design for this. I could mount the top wing normally--or upside down--and still have complete control over the incidence with a couple turns of a bolt. Would take all of 2 minutes to make those adjustments at the field.
Using the 4*40 as a design platform would certainly be cheaper than the 120. But, I have the wing kit for the 120 already, and I have the plans for the 120. I've got access to power tools (band saw, drill press, scroll saw, disk sander etc...) so scratching the fuse is really no big deal.
Does anybody have any comments on using semi-symmetrical wings on a bipe like this? How do you think it will fly.
How do you think it would effect the flying if that top wing was built upside down, so the flatter part of the wing was on top when flying? It's not something that I WANT to do. Just wondering if it would give the plane a more neutral feel.
Do other bipes have semi-symmetrical wings? Hog Bipe? Balsa USA Pheaton? GP Stearman? Do they all have fully symmetrical wings? Semi-symmetrical?
What are the disadvantages (if any) of going forward and just using the stock airfoil from the 120? It is going to need more negative incidence on the top wing or would the standard -1.0 up to -1.5 degrees be enough?
These are all design considerations that have just hit me. I'm REALLY concerned about the wings now. Don't want to build a plane that wants to climb all the time and takes 1/2 stick to fly inverted.
02-28-2008, 10:39 PM
#7
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RE: 4*120 Biplane Kit Bash?
I seem to remember seing a 4 star 40 bipe online before but I can't seem to find it now [&:] I think you are on the right track and should go for it! Can't wait to see the build-up.[sm=thumbup.gif]
02-28-2008, 10:54 PM
#8
Senior Member
RE: 4*120 Biplane Kit Bash?
Lots of bipes use a semi symmetrical airfoil. The lift is conteracted by the incidence. Good idea on making that adjustable. I assume the adjustments will be made on both the cabane and outer struts? Please share your technique when you get it hammered out.
02-29-2008, 12:16 AM
#10
RE: 4*120 Biplane Kit Bash?
The adjustable incidence would be accomplished pretty easily. I'd only need the top wing to be adjustable. I'll set the bottom wing in the stock saddle and zero the stab to that.
For the top wing, I will install some blocks of wood where the cabanes and inner struts attach to the wing. There would need to be a blind nut (6/32) installed into each block of wood. 6 attachment points on the top wing. 2 on each wing tip and 2 in the center.
I'd need a bolt with no head on it, but a hole though the shaft. The bolt will run up and into the block of wood thats buried inside the wing. The cabanes would be bolted to that bolt with another bolt and nylon lock nut.
Adjustment would be as simple as removing the 6 bolts from the cabanes and struts. Then twisting the 6/32 bolts in or out, depending on the desired incidence adjustment. It would be easy to turn all 3 rear bolts out to gain negative incidence. Then simply run the cabane bolts back through and lock them down.
I've attached a crude paint drawing of the type of bolt I'd need. The hole in the top of the bolt would be used to attach the cabanes and struts with a separate 4/40 bolt and nylon lock nut.
It might not be necessary to build all 6 attachment points in this manner. I might get away with just using 3 of them in the back of the wing. I could use those 3 bolts to move the trailing edge of the wing up and down.
2nd drawing is a side view.
3rd drawing is a rear view--looking forward at the trailing edge of the wing.
For the top wing, I will install some blocks of wood where the cabanes and inner struts attach to the wing. There would need to be a blind nut (6/32) installed into each block of wood. 6 attachment points on the top wing. 2 on each wing tip and 2 in the center.
I'd need a bolt with no head on it, but a hole though the shaft. The bolt will run up and into the block of wood thats buried inside the wing. The cabanes would be bolted to that bolt with another bolt and nylon lock nut.
Adjustment would be as simple as removing the 6 bolts from the cabanes and struts. Then twisting the 6/32 bolts in or out, depending on the desired incidence adjustment. It would be easy to turn all 3 rear bolts out to gain negative incidence. Then simply run the cabane bolts back through and lock them down.
I've attached a crude paint drawing of the type of bolt I'd need. The hole in the top of the bolt would be used to attach the cabanes and struts with a separate 4/40 bolt and nylon lock nut.
It might not be necessary to build all 6 attachment points in this manner. I might get away with just using 3 of them in the back of the wing. I could use those 3 bolts to move the trailing edge of the wing up and down.
2nd drawing is a side view.
3rd drawing is a rear view--looking forward at the trailing edge of the wing.
02-29-2008, 01:42 AM
#11
Senior Member
RE: 4*120 Biplane Kit Bash?
I think I see what your plan is, please update with photos if you can as you progress.
Rcpilot, a little off topic, but I find it hilarious how guys like you and me come up with these "crude paint drawings". Like we are drawing as neanderthals in a digital cave. Then somebody like Minnflyer comes along and blows it out of the water with his rendition. Go check out my Cor-Star 60 thread in the SPAD forum sometime. It looks like I did my graphics on an Atari 64! LOL!, Maybe an Apple 2c. Good Lord, I'm dating myself. [sm=red_smile.gif]
LEGAL RELEASE: Dating meaning time, not 'dating' as in the ritual humans do to find compatibility among other humans to carry on a meaningful relationship that will last til death (or until they just get sick of each other). I just turned 38; my hair is thinning a bit, but I have managed to still maintain an occasional youthful acne flare up. So I guess it all evens out in the end.
Rcpilot, a little off topic, but I find it hilarious how guys like you and me come up with these "crude paint drawings". Like we are drawing as neanderthals in a digital cave. Then somebody like Minnflyer comes along and blows it out of the water with his rendition. Go check out my Cor-Star 60 thread in the SPAD forum sometime. It looks like I did my graphics on an Atari 64! LOL!, Maybe an Apple 2c. Good Lord, I'm dating myself. [sm=red_smile.gif]
LEGAL RELEASE: Dating meaning time, not 'dating' as in the ritual humans do to find compatibility among other humans to carry on a meaningful relationship that will last til death (or until they just get sick of each other). I just turned 38; my hair is thinning a bit, but I have managed to still maintain an occasional youthful acne flare up. So I guess it all evens out in the end.
02-29-2008, 02:51 AM
#12
RE: 4*120 Biplane Kit Bash?
ORIGINAL: Deadeye
Rcpilot, a little off topic, but I find it hilarious how guys like you and me come up with these "crude paint drawings". Like we are drawing as neanderthals in a digital cave. Then somebody like Minnflyer comes along and blows it out of the water with his rendition. Go check out my Cor-Star 60 thread in the SPAD forum sometime. It looks like I did my graphics on an Atari 64! LOL!, Maybe an Apple 2c. Good Lord, I'm dating myself. [sm=red_smile.gif]
Rcpilot, a little off topic, but I find it hilarious how guys like you and me come up with these "crude paint drawings". Like we are drawing as neanderthals in a digital cave. Then somebody like Minnflyer comes along and blows it out of the water with his rendition. Go check out my Cor-Star 60 thread in the SPAD forum sometime. It looks like I did my graphics on an Atari 64! LOL!, Maybe an Apple 2c. Good Lord, I'm dating myself. [sm=red_smile.gif]
Nice job with viewing the JPEG pics and the editing thrown in though. I just learned how to do that last year.I'm 36 and my hair is 45% gray already. I smoked for most of the last 9yrs. Finally quit about 4 months ago, but I think it put some years on me. Totally stupid. I didn't start smoking until I was in my late 20's.
Not like the usual kid who picks it up at 16 and then can't quit. I waited until I was over 25 to develope/nurture my nasty habits. Oh well, I managed to quit.I just hope I don't pick it up again next season during training nights. I'm a volunteer instructor at the club and it can be a bit stressful dealing with newbies every Thursday night for 5hrs. [
] My usual consumption was 1 pack during the week, and then a whole friggin' pack on Thursday evening. [:'(]I need to find a place to get those bolts. I might prototype the design and see how it works. I'm worried about it being "floppy". I felt like the outer cabanes should seat on the wing surface kinda snug. If I jack the back end up 1/16" to get negative incidence--then the cabane won't touch the bottom surface of the wing. [sm=confused.gif]
02-29-2008, 08:50 AM
#13
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RE: 4*120 Biplane Kit Bash?
ORIGINAL: Rcpilot
I need to find a place to get those bolts. I might prototype the design and see how it works. I'm worried about it being "floppy". I felt like the outer cabanes should seat on the wing surface kinda snug. If I jack the back end up 1/16" to get negative incidence--then the cabane won't touch the bottom surface of the wing. [sm=confused.gif]
I need to find a place to get those bolts. I might prototype the design and see how it works. I'm worried about it being "floppy". I felt like the outer cabanes should seat on the wing surface kinda snug. If I jack the back end up 1/16" to get negative incidence--then the cabane won't touch the bottom surface of the wing. [sm=confused.gif]
- I too use MS Paint to illustrate for RCU and my random design ideas while I am at work
... it is a very simple program, but can make great 2d drawings to explain things.
02-29-2008, 12:38 PM
#14
RE: 4*120 Biplane Kit Bash?
Ace R/C offered a 4-120 Bipe kit years ago. I'm pretty sure it was a derivative of their 4-120 monoplane. Might be worthwhile to do a design comparison between the two before making any dimension commitments. Good luck with it. I love a good kit-bash. Mike.
02-29-2008, 03:18 PM
#15
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RE: 4*120 Biplane Kit Bash?
And don't forget the bash of the 4-120 into a pseudo- Ultimate bipe with slightly swept wings and the Ultimate tail fin. ..........a R/C Modeler contruction article.
02-29-2008, 04:07 PM
#16
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RE: 4*120 Biplane Kit Bash?
I'm thinking of doing something similar to one of my Senior Telemaster kits (95" version). I figure adding a bottom wing would make it look something like a squarish cabin bipe of the Thirties.
While it would be more efficient to reduce the thickness of the wings in a full scale aircraft, because we modelers fly in a rather small place where building up speed only means that you have to turn sooner, I like my models to be draggy. Leaving the airfoil stock permits me to use the existing wing ribs, etc., which saves me money and aggravation. I tend to add drag to my models intentionally. Lots of drag also means that it is easier to fly from smaller spaces.
Ed Cregger
While it would be more efficient to reduce the thickness of the wings in a full scale aircraft, because we modelers fly in a rather small place where building up speed only means that you have to turn sooner, I like my models to be draggy. Leaving the airfoil stock permits me to use the existing wing ribs, etc., which saves me money and aggravation. I tend to add drag to my models intentionally. Lots of drag also means that it is easier to fly from smaller spaces.
Ed Cregger
02-29-2008, 04:18 PM
#17
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RE: 4*120 Biplane Kit Bash?
ORIGINAL: Rcpilot
I couldn't do a project like this without documenting it all. I'm not sure how many of you saw my 4*120 build thread from 2005. I really enjoyed doing that thread and having people follow along with it. Several other guys were building the same plane and contributed great information to the thread.
I've been talking with my best flying buddy. He thinks it will not fly very good with a semi-symmetrical wing. I have my doubts too.
All of the 4* designs fly very well. We discussed doing some experiments with the 4*40 first. One of the things we talked about was to put the top wing on upside down. Then, when you fly inverted, it's all the same. I would need to build my outer cabanes and inter struts with an adjustable bolt so that I could adjust the incidence between flights. We came up with a simple but effective design for this. I could mount the top wing normally--or upside down--and still have complete control over the incidence with a couple turns of a bolt. Would take all of 2 minutes to make those adjustments at the field.
Using the 4*40 as a design platform would certainly be cheaper than the 120. But, I have the wing kit for the 120 already, and I have the plans for the 120. I've got access to power tools (band saw, drill press, scroll saw, disk sander etc...) so scratching the fuse is really no big deal.
Does anybody have any comments on using semi-symmetrical wings on a bipe like this? How do you think it will fly.
How do you think it would effect the flying if that top wing was built upside down, so the flatter part of the wing was on top when flying? It's not something that I WANT to do. Just wondering if it would give the plane a more neutral feel.
Do other bipes have semi-symmetrical wings? Hog Bipe? Balsa USA Pheaton? GP Stearman? Do they all have fully symmetrical wings? Semi-symmetrical?
What are the disadvantages (if any) of going forward and just using the stock airfoil from the 120? It is going to need more negative incidence on the top wing or would the standard -1.0 up to -1.5 degrees be enough?
These are all design considerations that have just hit me. I'm REALLY concerned about the wings now. Don't want to build a plane that wants to climb all the time and takes 1/2 stick to fly inverted.
I couldn't do a project like this without documenting it all. I'm not sure how many of you saw my 4*120 build thread from 2005. I really enjoyed doing that thread and having people follow along with it. Several other guys were building the same plane and contributed great information to the thread.
I've been talking with my best flying buddy. He thinks it will not fly very good with a semi-symmetrical wing. I have my doubts too.
All of the 4* designs fly very well. We discussed doing some experiments with the 4*40 first. One of the things we talked about was to put the top wing on upside down. Then, when you fly inverted, it's all the same. I would need to build my outer cabanes and inter struts with an adjustable bolt so that I could adjust the incidence between flights. We came up with a simple but effective design for this. I could mount the top wing normally--or upside down--and still have complete control over the incidence with a couple turns of a bolt. Would take all of 2 minutes to make those adjustments at the field.
Using the 4*40 as a design platform would certainly be cheaper than the 120. But, I have the wing kit for the 120 already, and I have the plans for the 120. I've got access to power tools (band saw, drill press, scroll saw, disk sander etc...) so scratching the fuse is really no big deal.
Does anybody have any comments on using semi-symmetrical wings on a bipe like this? How do you think it will fly.
How do you think it would effect the flying if that top wing was built upside down, so the flatter part of the wing was on top when flying? It's not something that I WANT to do. Just wondering if it would give the plane a more neutral feel.
Do other bipes have semi-symmetrical wings? Hog Bipe? Balsa USA Pheaton? GP Stearman? Do they all have fully symmetrical wings? Semi-symmetrical?
What are the disadvantages (if any) of going forward and just using the stock airfoil from the 120? It is going to need more negative incidence on the top wing or would the standard -1.0 up to -1.5 degrees be enough?
These are all design considerations that have just hit me. I'm REALLY concerned about the wings now. Don't want to build a plane that wants to climb all the time and takes 1/2 stick to fly inverted.
----------------
It depends upon what kind of performance you are anticipating, as to whether the semi-symmetrical airfoil will satisfy your needs.
Fortunately, the semi-symmetrical airfoil is the best compromise for most types of flying, although I do favor fully symmetrical airfoils the majority of the time.
I flew a Balsa USA Phaeton Biplane (original version) for a couple of years in the early Eighties. I'm a part time pattern pilot, or used to be, and I didn't experience any major disadvantages with its semi-symmetrical airfoiled wings. I do wish the Phaeton had ailerons on the top wing, but I got by with lots of control throw on the lower wing ailerons. I just got by, though.
I did incorporate 1/2 degree of negative incidence in the top wing as an experiment. It turned out to be the best flying biplane I've ever flown. It locked into the groove and performed amazingly well. The 1/2 degree of negative incidence idea was picked up from reading a Don Lowe article in RCM. All of my bipes now get that treatment.
My Phaeton was slightly underpowered with the then new Super Tigre .40S. A sixty would not have been out of place, but I stuck with the .40 and learned a lot about energy conservation. <G>
One thing new biplane flyers must get used to is immediately lowering the nose should the engine quit. Mine had the glide ratio of the Space Shuttle or a dropped manhole cover. You have to fly as though you're playing musical chairs and knowing that the music (of the engine) may stop at any time. Fly upwind and in close, so you can make it back to the field after you recognize that the engine has quit. Cheat a bit and fly your four-stroke with the muffler off on busy days at the field (get a Perry VP-20 shaker pump so you won't miss the muffler pressure). Or use a louder two-stroke.
Ed Cregger
03-02-2008, 01:03 PM
#19
RE: 4*120 Biplane Kit Bash?
ORIGINAL: WhiteRook
you have a great idea, i dont know why sig doesn't redesign this bird . a round fuse would look
great!! one way might be to add formers on the square sides.
you have a great idea, i dont know why sig doesn't redesign this bird . a round fuse would look
great!! one way might be to add formers on the square sides.
A few balsa formers and some thin stringers would round it out really nice.Sig didn't design it. Bruce Tharpe designed it many years ago. He's moved on and started his own company. I doubt Sig will ever redesign it. But thats okay. The 4* planes make a solid base to bash from. I think I'd rather that they leave the designs alone.
01-14-2009, 10:53 PM
#20
RE: 4*120 Biplane Kit Bash?
Well, here I am almost a year later and I'm ready to start this project. I've had a wing kit for over a year. Maybe even a year and a half. RCU member RETNAVYCDR hooked me up with a NIB 4*120 kit REALLY cheap. He bought it in the marketplace and gave it to me. FREE!! [X(]
Thanks Roger [sm=thumbs_up.gif]
I don't really like the fuse on the 4*120. It's too narrow and too short. I think I've had about 5 or 6 of the 4* planes in my short 10yrs in this hobby. I've got a new 4*40 ARF that was assembled just a few weeks ago and I built the kit a few years back. I've built the 4*120 kit back in 2005 and I think it was around 2000 when I built the 4*60 kit. Also had a 4*60 ARF somewhere along the way as well. None of them knife edge very well. Not enough side area IMO. I'd really like to widen the fuse about 2" and also make it about 2" taller. I'd also like to add about 5" to the length. Not really sure WHERE to add the length though. 5" behind the wing could lead to a tail heavy design. It might be prudent to add about 1" or 2" in front of the wing and 3" behind the wing. This whole new fuselage design would involve a 4x8 sheet of lite-ply and a bunch of cutting on the band saw. I'd have to enlarge every former inside the fuse. I don't think it will be that hard to enlarge the fuse, just a lot of time.
I've been looking at the plans and I think the top and bottom wings need to be spaced apart about 16" to make it look right. I would probably move the top wing forward about 4" and leave the bottom wing in the stock saddle.
I'm going to clip one bay off each wing tip. This will reduce the span to 72". That fits in the back of my Nissan truck. I did the math and I think that gives about 2140 square inches of wing area on this bipe. I'm anticipating a flying weight between 17-19 pounds. I have a Fox 52cc gasser collecting dust. That should provide very good sport power at my flying altitude of almost 6000'
I need to cover a Mojo 60 and clean the shop. Planning to get started in the next week or two. Hop aboard fellas!! There's another build thread coming to a computer monitor near you!! [8D]
Thanks Roger [sm=thumbs_up.gif]
I don't really like the fuse on the 4*120. It's too narrow and too short. I think I've had about 5 or 6 of the 4* planes in my short 10yrs in this hobby. I've got a new 4*40 ARF that was assembled just a few weeks ago and I built the kit a few years back. I've built the 4*120 kit back in 2005 and I think it was around 2000 when I built the 4*60 kit. Also had a 4*60 ARF somewhere along the way as well. None of them knife edge very well. Not enough side area IMO. I'd really like to widen the fuse about 2" and also make it about 2" taller. I'd also like to add about 5" to the length. Not really sure WHERE to add the length though. 5" behind the wing could lead to a tail heavy design. It might be prudent to add about 1" or 2" in front of the wing and 3" behind the wing. This whole new fuselage design would involve a 4x8 sheet of lite-ply and a bunch of cutting on the band saw. I'd have to enlarge every former inside the fuse. I don't think it will be that hard to enlarge the fuse, just a lot of time.
I've been looking at the plans and I think the top and bottom wings need to be spaced apart about 16" to make it look right. I would probably move the top wing forward about 4" and leave the bottom wing in the stock saddle.
I'm going to clip one bay off each wing tip. This will reduce the span to 72". That fits in the back of my Nissan truck. I did the math and I think that gives about 2140 square inches of wing area on this bipe. I'm anticipating a flying weight between 17-19 pounds. I have a Fox 52cc gasser collecting dust. That should provide very good sport power at my flying altitude of almost 6000'
I need to cover a Mojo 60 and clean the shop. Planning to get started in the next week or two. Hop aboard fellas!! There's another build thread coming to a computer monitor near you!! [8D]
01-15-2009, 10:50 AM
#22
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RE: 4*120 Biplane Kit Bash?
This'll be fun to watch.....
I'm no engineer, let alone one expert in aeronautics... but I hack my way through...
I was thinking on your cabane adjusters...
I was thinking of a slightly different solution....
I'd use a piece of square stock on the bottom side of the upper wing. It'd be bolted to the bottom of the top wing, and the cabane would be bolted to the side of it. Then as you experiment with incidences, you could add spacers between the square stock and the wing.
If you got too many spacers for your own comfort, make new cabanes and/or square stock pieces. Heck you could even use this method to shift the wing forwards/backwards.
You're not building a supersonic fighter. It doesn't need to be uber strong. With all the wing frontal area and drag, that piece of stock isn't going to be noticable.
Just a thought.. take it for what it's worth....
I'm no engineer, let alone one expert in aeronautics... but I hack my way through...
I was thinking on your cabane adjusters...
I was thinking of a slightly different solution....
I'd use a piece of square stock on the bottom side of the upper wing. It'd be bolted to the bottom of the top wing, and the cabane would be bolted to the side of it. Then as you experiment with incidences, you could add spacers between the square stock and the wing.
If you got too many spacers for your own comfort, make new cabanes and/or square stock pieces. Heck you could even use this method to shift the wing forwards/backwards.
You're not building a supersonic fighter. It doesn't need to be uber strong. With all the wing frontal area and drag, that piece of stock isn't going to be noticable.
Just a thought.. take it for what it's worth....
