Aerodynamic considerations for a speed plane design
03-30-2008, 11:21 PM
#26
RE: Aerodynamic considerations for a speed plane design
Yes but in my case I'm working with a .40 sized piston with a half inch stroke changing direction 500 times per second. I'm not sure that the net result [in mph] of side mounting my rear exhaust engine would be significant, even if there was a couple hundred rpm difference.
Lowering drag has to take priority over a fractional HP gain.
Lowering drag has to take priority over a fractional HP gain.
03-30-2008, 11:28 PM
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RE: Aerodynamic considerations for a speed plane design
A couple hundred rpm is just that, more power=more speed, depends upon pitch also. But beyond that the prop is going to be spinning in a more perfect circle and that would also help some.
Plus you rear exhaust engine can be piped out through the fuselage, no muffler or pipe hanging out in the air stream to create drag.
Plus you rear exhaust engine can be piped out through the fuselage, no muffler or pipe hanging out in the air stream to create drag.
03-30-2008, 11:47 PM
#28
RE: Aerodynamic considerations for a speed plane design
I'm a little bit too backed up with projects to draw something up right now. If you know what the Nelson FAI engine looks like [pipe and all], side mounting it will leave you with one of two extreme outcomes.......either something very, very cool.......or something that is extremely dorky and hideous, ugly enough to make an onion cry 
03-31-2008, 01:08 AM
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RE: Aerodynamic considerations for a speed plane design
A BWB would be a good design to start with. But keep in mind that small frontal area is king. That means no thick wings and the blending should take place over a very small distance. Almost a double delta planform. Also if you're smart you'll find a ducted fan engine that has the power and RPM and combines that with a rear exhuast setup so the pipe can be in the wing itself. Some fancy composite center spar design will allow the pipe to pass through and the loads to be slipped around with a carbon fiber hoolahoop around the pipe and connect the spars on either side.
Also there's material out there that supports the idea that a wing to fuselage joint of 90 or more degrees in angle doesn't need a fillet. The Corsair took advantage of that finding and had no fillets at all.
Also there's material out there that supports the idea that a wing to fuselage joint of 90 or more degrees in angle doesn't need a fillet. The Corsair took advantage of that finding and had no fillets at all.
03-31-2008, 11:20 PM
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RE: Aerodynamic considerations for a speed plane design
Bruce,
A double delta planform sounds like a good idea to me.
Lets see the cheeks blend into chines that go into the main delta is what springs to mind here.
As far as a motor I have a brand new OS 91 VF-DF with a tuned pipe and remote mix valve think that would work?
I want to if possible keep the exhaust internal and just pipe it out so a composite spar was already in the back of my mind as far as the basic structure goes. Where I really am interested in the BWB concept the spars will probably be built into a series of formers that will make up the fuselage and wing root. The internal structure is going to take some time to design but should not be all that bad to build.
I would like to see if I can keep as much of the control setup and linkages, as possible, within the confines of the fuselage. That may take some jumping through hoops but not impossible.
I may start putting together some sketches soon, but I am in the middle of a build at the moment, and have to build a Senorita for my daughter for this spring. That will be pretty stock and a fast build, but I also have my oddball design I would like to at least get the ½ size test plane built for this year as well. So this speed plane may not actually hit the bench before mid summer but I can work on the design here and there.
A double delta planform sounds like a good idea to me.
Lets see the cheeks blend into chines that go into the main delta is what springs to mind here.
As far as a motor I have a brand new OS 91 VF-DF with a tuned pipe and remote mix valve think that would work?
I want to if possible keep the exhaust internal and just pipe it out so a composite spar was already in the back of my mind as far as the basic structure goes. Where I really am interested in the BWB concept the spars will probably be built into a series of formers that will make up the fuselage and wing root. The internal structure is going to take some time to design but should not be all that bad to build.
I would like to see if I can keep as much of the control setup and linkages, as possible, within the confines of the fuselage. That may take some jumping through hoops but not impossible.
I may start putting together some sketches soon, but I am in the middle of a build at the moment, and have to build a Senorita for my daughter for this spring. That will be pretty stock and a fast build, but I also have my oddball design I would like to at least get the ½ size test plane built for this year as well. So this speed plane may not actually hit the bench before mid summer but I can work on the design here and there.
04-01-2008, 12:40 AM
#31
RE: Aerodynamic considerations for a speed plane design
High Plains is gonna put his slide rule away and go help someone else if you start talking deltas.
For any serious speed project, I've washed my hands of them. For all the effort that Croundy put into that beautiful monster delta of his, he wasn't rewarded with even as much speed as a typical FAI pylon model.
For any serious speed project, I've washed my hands of them. For all the effort that Croundy put into that beautiful monster delta of his, he wasn't rewarded with even as much speed as a typical FAI pylon model.
04-01-2008, 01:18 AM
#32
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RE: Aerodynamic considerations for a speed plane design
I put my Pickett slip stick away years ago, for an HP 45. Damn thing cost me as more than my Kraft KP-4 SS radio. That's single stick, not spread spectrum.
Deltas are slow, but their saving grace is that they are easy to land. But if you are using gravity to add power, you lose efficency when you have to pull out.
If you look at the results of the German speed events from a couple of years ago, you will find that the pylon based 6.5cc powered model topped out at 208 mph. The 15cc only did about 226 mph with 2.3 times as much displacement. If the engine power output is somewhat proportional to displacement, then I would have expected at least double the power with the larger engine. That should have been enough to push a plane with simular drag to over 260 mph.
So you can conclude that either the larger engine just is not making the power, or the drag of the airframe was much higher than the racer.
The pylon ship has a very high aspect ratio wing, so it will maintain the dive speed better though the traps.
Deltas are slow, but their saving grace is that they are easy to land. But if you are using gravity to add power, you lose efficency when you have to pull out.
If you look at the results of the German speed events from a couple of years ago, you will find that the pylon based 6.5cc powered model topped out at 208 mph. The 15cc only did about 226 mph with 2.3 times as much displacement. If the engine power output is somewhat proportional to displacement, then I would have expected at least double the power with the larger engine. That should have been enough to push a plane with simular drag to over 260 mph.
So you can conclude that either the larger engine just is not making the power, or the drag of the airframe was much higher than the racer.
The pylon ship has a very high aspect ratio wing, so it will maintain the dive speed better though the traps.
04-01-2008, 08:29 PM
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RE: Aerodynamic considerations for a speed plane design
I guess the induced drag of a delta is an issue then?
Still there has to be a better way than an over powered glider?
Still there has to be a better way than an over powered glider?
04-01-2008, 08:42 PM
#34
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RE: Aerodynamic considerations for a speed plane design
Not really. At least when a pull-out from a dive is considered, induced drag becomes important. At the slow speeds that RC speed designs fly at, starting with a clean glider and making mods will get you there, while deltas and the like will be left in the dust.
04-01-2008, 09:00 PM
#35
RE: Aerodynamic considerations for a speed plane design
Well, if the timing zone and the "pre-timing-after-the-dive" zone are long enough...it will take a moderately loaded and efficient wing to carry it through with the least amount of drag at the end. Last summer I ran the Nelson .40 on a fairly clean delta and you could really see the speed bleed off quickly...inspite of the plane weighing less than 4 pounds.
The fastest designs in the world didn't just happen, they have been a work in progress that has taken decades to evolve.
To break the mold just a little bit would be to build a side mounted speedster, then do what it takes to blend the engine into the wing.
My guess is that it would take twice the effort and money to build a .90 sized plane, I'll stay with the .40...I know it will fit in my Jeep.
The fastest designs in the world didn't just happen, they have been a work in progress that has taken decades to evolve.
To break the mold just a little bit would be to build a side mounted speedster, then do what it takes to blend the engine into the wing.
My guess is that it would take twice the effort and money to build a .90 sized plane, I'll stay with the .40...I know it will fit in my Jeep.
04-01-2008, 09:56 PM
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RE: Aerodynamic considerations for a speed plane design
ORIGINAL: iron eagel
I guess the induced drag of a delta is an issue then?
Still there has to be a better way than an over powered glider?
I guess the induced drag of a delta is an issue then?
Still there has to be a better way than an over powered glider?
And have you noticed how all the latest full sized forumula 1 racers are getting away from the stubby Cassutt look and beginning to look a LOT like our model sized over powered hotliners? You can't buck City Hall, the IRS or Physics. A fast glider is going to be the fastest model overall regardless of how you slice and dice it. It may be different if the speed of sound was scalable but for each viscosity of liquid there's an ideal planform for going fast. And for air it ends up being a higher apect ratio wing on a fuselage that's only just barely able to contain the engine and the equipment. So really an overpowered glider is a very good option.
Another option might be a blended body swept flying wing. You get the aspect ratio along with potentially a very clean design. Using symetrical sections means you don't need very much twist for pitch stability at all. A thicker root section that holds the engine and gear and that quickly blends to a swept flying wing with tip fins. The required washout in such a wing combined with the tip fins ensures that the usual vortex formation at the wing tips will be minimized at the same time you're obtaining your pitch stability. And that way you also get your sexy wing fairings.
Sort of like this? Span 54 inches wing area around 500 sq inches speed cowl set up to hopefully hold a honkin' DF engine in the .60 to .90 range or similarly a control line speed engine of the same size. Pipe is buried in the flare of the wing and exits at the trailing edge. Airfoil would be one that promotes laminar flow for a longer portion of the chord to help minimize drag. Normally such airfoils don't work for us but the Reynolds numbers on this one should be good enough to support such a choice. Some number crunching would be needed to find out and some testing before using this. The wing would be made using a double skin with something like a structural foam core to produce upper and lower shells and the molds would be made using CNC machining to ensure total airfoil accuracy to a high degree. The tip fins and curved joiners would be added on after. As shown the wing starts out at 1 inch thick. That's about 8% as it sits now. I'd want to do some testing and figuring to see if there's gains to be had going to more of a 6% section. No point in going any thinner as then flutter may rear it's ugly head.
Whatcha all think?
04-01-2008, 10:01 PM
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RE: Aerodynamic considerations for a speed plane design
The reason for the big engine is that I have it...
Yes the airframe would be larger but you have more room to work with at least inside the fuselage.
It looks as if I have a "lot" to learn as far as model speed airplanes.
So other than deltas what other type of forms have been tried?
Earlier, I was asking about different types of full scale design concepts, and wonder how they might be applied to models.
Yes the airframe would be larger but you have more room to work with at least inside the fuselage.
It looks as if I have a "lot" to learn as far as model speed airplanes.
So other than deltas what other type of forms have been tried?
Earlier, I was asking about different types of full scale design concepts, and wonder how they might be applied to models.
04-01-2008, 10:23 PM
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RE: Aerodynamic considerations for a speed plane design
ORIGINAL: BMatthews
In turns yes it is. Pulling G with a delta produces a lot of drag
And have you noticed how all the latest full sized forumula 1 racers are getting away from the stubby Cassutt look and beginning to look a LOT like our model sized over powered hotliners? You can't buck City Hall, the IRS or Physics. A fast glider is going to be the fastest model overall regardless of how you slice and dice it. It may be different if the speed of sound was scalable but for each viscosity of liquid there's an ideal planform for going fast. And for air it ends up being a higher apect ratio wing on a fuselage that's only just barely able to contain the engine and the equipment. So really an overpowered glider is a very good option.
Another option might be a blended body swept flying wing. You get the aspect ratio along with potentially a very clean design. Using symetrical sections means you don't need very much twist for pitch stability at all. A thicker root section that holds the engine and gear and that quickly blends to a swept flying wing with tip fins. The required washout in such a wing combined with the tip fins ensures that the usual vortex formation at the wing tips will be minimized at the same time you're obtaining your pitch stability. And that way you also get your sexy wing fairings.
Sort of like this? Span 54 inches wing area around 500 sq inches speed cowl set up to hopefully hold a honkin' DF engine in the .60 to .90 range or similarly a control line speed engine of the same size. Pipe is buried in the flare of the wing and exits at the trailing edge. Airfoil would be one that promotes laminar flow for a longer portion of the chord to help minimize drag. Normally such airfoils don't work for us but the Reynolds numbers on this one should be good enough to support such a choice. Some number crunching would be needed to find out and some testing before using this. The wing would be made using a double skin with something like a structural foam core to produce upper and lower shells and the molds would be made using CNC machining to ensure total airfoil accuracy to a high degree. The tip fins and curved joiners would be added on after. As shown the wing starts out at 1 inch thick. That's about 8% as it sits now. I'd want to do some testing and figuring to see if there's gains to be had going to more of a 6% section. No point in going any thinner as then flutter may rear it's ugly head.
Whatcha all think?
ORIGINAL: iron eagel
I guess the induced drag of a delta is an issue then?
Still there has to be a better way than an over powered glider?
I guess the induced drag of a delta is an issue then?
Still there has to be a better way than an over powered glider?
And have you noticed how all the latest full sized forumula 1 racers are getting away from the stubby Cassutt look and beginning to look a LOT like our model sized over powered hotliners? You can't buck City Hall, the IRS or Physics. A fast glider is going to be the fastest model overall regardless of how you slice and dice it. It may be different if the speed of sound was scalable but for each viscosity of liquid there's an ideal planform for going fast. And for air it ends up being a higher apect ratio wing on a fuselage that's only just barely able to contain the engine and the equipment. So really an overpowered glider is a very good option.
Another option might be a blended body swept flying wing. You get the aspect ratio along with potentially a very clean design. Using symetrical sections means you don't need very much twist for pitch stability at all. A thicker root section that holds the engine and gear and that quickly blends to a swept flying wing with tip fins. The required washout in such a wing combined with the tip fins ensures that the usual vortex formation at the wing tips will be minimized at the same time you're obtaining your pitch stability. And that way you also get your sexy wing fairings.
Sort of like this? Span 54 inches wing area around 500 sq inches speed cowl set up to hopefully hold a honkin' DF engine in the .60 to .90 range or similarly a control line speed engine of the same size. Pipe is buried in the flare of the wing and exits at the trailing edge. Airfoil would be one that promotes laminar flow for a longer portion of the chord to help minimize drag. Normally such airfoils don't work for us but the Reynolds numbers on this one should be good enough to support such a choice. Some number crunching would be needed to find out and some testing before using this. The wing would be made using a double skin with something like a structural foam core to produce upper and lower shells and the molds would be made using CNC machining to ensure total airfoil accuracy to a high degree. The tip fins and curved joiners would be added on after. As shown the wing starts out at 1 inch thick. That's about 8% as it sits now. I'd want to do some testing and figuring to see if there's gains to be had going to more of a 6% section. No point in going any thinner as then flutter may rear it's ugly head.
Whatcha all think?
I like it, but I do not know all that much when it comes to models. That looks something like a full size aircraft that is in development now for GA, it is called the Atlantica by Wingco.
Isn't a flying wing is supposed to fairly low drag?
I would like to ask a question, why was something like a canard dismissed so quickly?
In GA they are amongst some of the quickest piston powered airplanes, sometimes called a poor mans jet. One airplane that I would offer as an example is the Velocity quick and long range for 70 gal of fuel.
04-01-2008, 10:57 PM
#40
RE: Aerodynamic considerations for a speed plane design
IE, an early Speed Cup design was shaped like a boomerang with elevons on the trailing edge of the wing tips. Very unique. Same idea as the early British "Electric Lightning" jets of the 50s. Kind of a cross between a delta and a flying wing.
I built a swept wing flying wing for .049 power a couple of years ago....with the engine in back. It's a fast little guy, the problem is carving nice pusher props for it...then gluing them back together every other landing. One of the problems with a pusher is that the engine needs to get airborne ASAP before meltdown, plus the fuel and exhaust systems get set up bassackwards. The lack of nice pusher props also is a hurdle. If you're thinking about a pusher canard, these would be some obstacles.
I built a swept wing flying wing for .049 power a couple of years ago....with the engine in back. It's a fast little guy, the problem is carving nice pusher props for it...then gluing them back together every other landing. One of the problems with a pusher is that the engine needs to get airborne ASAP before meltdown, plus the fuel and exhaust systems get set up bassackwards. The lack of nice pusher props also is a hurdle. If you're thinking about a pusher canard, these would be some obstacles.
04-01-2008, 11:15 PM
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RE: Aerodynamic considerations for a speed plane design
ORIGINAL: combatpigg
IE, an early Speed Cup design was shaped like a boomerang with elevons on the trailing edge of the wing tips. Very unique. Same idea as the early British "Electric Lightning" jets of the 50s. Kind of a cross between a delta and a flying wing.
I built a swept wing flying wing for .049 power a couple of years ago....with the engine in back. It's a fast little guy, the problem is carving nice pusher props for it...then gluing them back together every other landing. One of the problems with a pusher is that the engine needs to get airborne ASAP before meltdown, plus the fuel and exhaust systems get set up bassackwards. The lack of nice pusher props also is a hurdle. If you're thinking about a pusher canard, these would be some obstacles.
IE, an early Speed Cup design was shaped like a boomerang with elevons on the trailing edge of the wing tips. Very unique. Same idea as the early British "Electric Lightning" jets of the 50s. Kind of a cross between a delta and a flying wing.
I built a swept wing flying wing for .049 power a couple of years ago....with the engine in back. It's a fast little guy, the problem is carving nice pusher props for it...then gluing them back together every other landing. One of the problems with a pusher is that the engine needs to get airborne ASAP before meltdown, plus the fuel and exhaust systems get set up bassackwards. The lack of nice pusher props also is a hurdle. If you're thinking about a pusher canard, these would be some obstacles.
I do like the flying wing type of concept but that is just my eye and not backed up by any physics...
But as I said this is an educational experience for me, obviously!
04-01-2008, 11:41 PM
#43
RE: Aerodynamic considerations for a speed plane design
All you can really do is use conventional wisdom and gleaned knowledge...if possible blend in your intuition when in doubt. What I like about Bruces' drawing is not only is it a simple, handsome looking plane, but also unique. I'm not sure about those big winglets at 200 mph unless the wing is really stiff.
IE, model sized canards have always been a curiosity but it seems that they don't really begin to shine until you move up to large scale craft.
IE, model sized canards have always been a curiosity but it seems that they don't really begin to shine until you move up to large scale craft.
04-01-2008, 11:53 PM
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RE: Aerodynamic considerations for a speed plane design
If you guys are really itching to help me avoid loosing it in a crash I COULD send you the actual CAD file....
I was thinking about this a little more. Foilsim is a great quickie tool for studying stuff like this. It tells me that a model wing of roughly 400 sq inches moving at 180 mph only needs to have 0.16 to .24 degree angle of attack for a 4 lb to 6.5lb lift. Now I know that the wing twist needed for such a plane would be far more than this and that means the tips will be operating at a much higher negative angle and producing unwanted drag. So..... What I'm thinking now is that I'll get the "twist" by using elevon up trim and that this up trim will be trimmed out as the speed builds by using the elevator trim or using a mix to set the elevons for low speed or high speed. Wing twist will be in the order of about .3 to .35 degree so there's some there for the high speed part.
This will also mean that the model will have to have a fairly aggresive CG position to avoid the need for more twist. I'm thinking that a semiconductor heli "gyro" on the elevator side would not be a bad idea to soften the response that would come from a relatively aggresive CG location. Certainly the low rate switches would be thrown as the model passes over the top and before the speed builds. Perhaps that would be enough to soften the response?
My first thought is that this makes the flying wing layout too critical. But any layout is going to be critical at these speeds.
As for canards there's nothing at all magical about them. The commercial and experimental canards achieve their performance from the engines and power to weight ratios and aerodynamic cleanliness that is built in to the planes thanks to the airfoil selections and overall clean airframes. The fact that they put the small one out front has nothing to do with it. The same planes at the same weight with the same engines but with the wings switched around would fly just as fast.
I was thinking about this a little more. Foilsim is a great quickie tool for studying stuff like this. It tells me that a model wing of roughly 400 sq inches moving at 180 mph only needs to have 0.16 to .24 degree angle of attack for a 4 lb to 6.5lb lift. Now I know that the wing twist needed for such a plane would be far more than this and that means the tips will be operating at a much higher negative angle and producing unwanted drag. So..... What I'm thinking now is that I'll get the "twist" by using elevon up trim and that this up trim will be trimmed out as the speed builds by using the elevator trim or using a mix to set the elevons for low speed or high speed. Wing twist will be in the order of about .3 to .35 degree so there's some there for the high speed part.
This will also mean that the model will have to have a fairly aggresive CG position to avoid the need for more twist. I'm thinking that a semiconductor heli "gyro" on the elevator side would not be a bad idea to soften the response that would come from a relatively aggresive CG location. Certainly the low rate switches would be thrown as the model passes over the top and before the speed builds. Perhaps that would be enough to soften the response?
My first thought is that this makes the flying wing layout too critical. But any layout is going to be critical at these speeds.
As for canards there's nothing at all magical about them. The commercial and experimental canards achieve their performance from the engines and power to weight ratios and aerodynamic cleanliness that is built in to the planes thanks to the airfoil selections and overall clean airframes. The fact that they put the small one out front has nothing to do with it. The same planes at the same weight with the same engines but with the wings switched around would fly just as fast.
04-02-2008, 06:07 AM
#46
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RE: Aerodynamic considerations for a speed plane design
ORIGINAL: iron eagel
Isn't a flying wing is supposed to fairly low drag?
Isn't a flying wing is supposed to fairly low drag?
If you approach the problem of speed and only consider cruise, the reduction in parasitic drag with the deletion of the fuselage and tail and whatever else is a winner.
But if you expect to operate the sucker and expect to turn or pitch it just prior to the speed traps, the induced drag comes back to haunt you.
The kicker is that pitch stability for a flying wing leans toward lower AR wings.
And if you decide to go with a higher aspect ratio flying wing, the pitch stability becomes so critical that human pilots simply can't cope. I would hazzard a guess that with computer aided control flight, we might someday see high speed, high AR flying wings, but not with some poor chump on board.
04-02-2008, 07:23 AM
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RE: Aerodynamic considerations for a speed plane design
So using something like a "gyro" or some form of electronic stabilization would be a must for a high AR "flying Wing". If we were to use a form of electronic damping such as Bruce proposed would it be worth a shot?
So other than straight and level flight most other designs do not lend themselves to high speed flight.
Very interesting I am starting to understand high speed models to some small degree. I think...
Gee, it seemed so simple just a clean airframe and lots of power, guess that doesn't apply to real world.
So other than straight and level flight most other designs do not lend themselves to high speed flight.
Very interesting I am starting to understand high speed models to some small degree. I think...
Gee, it seemed so simple just a clean airframe and lots of power, guess that doesn't apply to real world.
04-02-2008, 08:01 AM
#48
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RE: Aerodynamic considerations for a speed plane design
ORIGINAL: iron eagel
So using something like a "gyro" or some form of electronic stabilization would be a must for a high AR "flying Wing". If we were to use a form of electronic damping such as Bruce proposed would it be worth a shot?
So other than straight and level flight most other designs do not lend themselves to high speed flight.
Very interesting I am starting to understand high speed models to some small degree. I think...
Gee, it seemed so simple just a clean airframe and lots of power, guess that doesn't apply to real world.
So using something like a "gyro" or some form of electronic stabilization would be a must for a high AR "flying Wing". If we were to use a form of electronic damping such as Bruce proposed would it be worth a shot?
So other than straight and level flight most other designs do not lend themselves to high speed flight.
Very interesting I am starting to understand high speed models to some small degree. I think...
Gee, it seemed so simple just a clean airframe and lots of power, guess that doesn't apply to real world.
Worth a shot?
You betcha. Anything in modeling is worth it. Whether or not the technology we have available for our models would work in the flight envelope required in a speed attempt would be a major consideration however. The good thing about the pitch problem for models is that they don't have shifting CG's like full scale birds do. Put the fuel tank on the CG and you got a lot solved for a model. That is, if your design even needs a tank.
I think what the major development you would have to work out for a high aspect ratio flying wing would be creating effective flying surfaces that would work at the two ends of the envelope. Expo can only do so much.
So other than straight and level flight most other designs do not lend themselves to high speed flight.
Other designs actually do work well for high speed flight but might not have the ultimate potential that a wing-only design has. And they all share the same problem with the aspect ratio. Other designs do lend themselves to high speed simply because they do handle the whole envelope within the requirements needed to get the airplane over to where it needs to be fast, and back.
There are considerations that dictate other choices. Suppose you have choose to use the fastest powerplant you own. And you own a jet engine. And it's 24" long. You're going to have to create a wing of enormous span for a model if you want to have a high aspect ratio wing that completely encloses that engine. So another design, one with a fuselage, does lend itself to the high speed flight you can attempt with your model within your choice of competition.
If we rephrase the sentence, "So other than straight and level flight most other designs do not lend themselves to successful high speed flight." it's easy to see what really happens in the design process. And the answer, "actually they do quite well" is easy to see. But right now, it's probably going to be a huge undertaking to create a record breaking model flying wing that we could fly successfully. But, damn if it wouldn't be fun to try.
04-02-2008, 08:17 AM
#49
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RE: Aerodynamic considerations for a speed plane design
While Bruce's speed delta design concept would be fast and very sexy looking, I don't think it would be as fast as a conventional design because we are not going to be operating at 500 knots. So the swept back wing sweep is going to hurt you with span wise flow. However if absolute speed possible is not the mission, go with sexy looking.
A RC prop speed model will be working at Reynold numbers very close to what 15 meter competition gliders are working at.
A RC prop speed model will be working at Reynold numbers very close to what 15 meter competition gliders are working at.
04-02-2008, 09:35 AM
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RE: Aerodynamic considerations for a speed plane design
ORIGINAL: HighPlains
A RC prop speed model will be working at Reynold numbers very close to what 15 meter competition gliders are working at.
A RC prop speed model will be working at Reynold numbers very close to what 15 meter competition gliders are working at.
I would like to see how fast we could make a prop driven model go.
Gee, now I can see two types of high speed planes that I would like to work with...
One that is for absolute BTW speed, the other a fairly radical high aspect ratio flying wing. Got into this thinking about one airplane now I can already see two, when will the madness end?
As far as Bruce's idea it would also be neat to see what can be done with something like that, I am up for this challenge as well.
DA you said that the effective control surfaces would be an issue that would have to be worked out.
Keeping that in mind has anyone tried vectored thrust via a ducted fan, or is that too limiting. You can stop laughing now...
HighPlains your are probably just shaking your head, thinking about someone who would want to try two projects like this at once.
At least I'll keep you guys entertained.
Oh well time to head off to work...