dihedral wing vs 4 ch
05-11-2019, 12:39 PM
#1
dihedral wing vs 4 ch
can a dihedral wing have ailerons? Are V wing aircraft always 3ch? By Vwing I do not mean the flying wing type, I mean the wings that slant up from the center . Do they ever come that way from factory or do you have to modify it?
Last edited by obrien135; 05-11-2019 at 01:32 PM.
05-11-2019, 05:28 PM
#2
Many trainers do come with dihedral in the wing, if that's what you are referring to. That said, I can't say what you will find with the latest foam planes but, with a wood ARF for kit, there will be some. A plane with ailerons will perform best with a low amount of dihedral as anything greater will have the wings fighting the ailerons. It really depends on the plane as to whether it has ailerons or not. I'm currently building a pair of Sig Kadet Jrs from plans. This plane is designed with a 48" wingspan with 2" of dihedral due to it's 3 channel design. I'm building mine with between no dihedral and .5" so that ailerons will be effective on both. Had I left the wings with the designed dihedral, ailerons would have been a waste of time
05-12-2019, 04:23 AM
#4
Banned
In WWI a common practice for both loops and rolls was to dive first to build up some speed. So even the real ones can have trouble with the maneuver.
05-12-2019, 01:07 PM
#6
With all things it will depend on the expectations of the airplane. There are quite a few examples out there of airplanes with a fair amount of dihedral with ailerons. One example that comes to mind are modern full house sailplanes. In fact most have polyhedral. 2 degrees at the center with an additional 6-8 degrees on the tip panels is very common. Something like a Piper Cherokee is also another good example.
05-15-2019, 05:29 AM
#7
The difference with a Piper Cherokee is it's a low wing aircraft that needs that dihedral to be stable in level flight. A high wing design doesn't need anywhere near the dihedral since all of the plane's weight is below the wing, not above it, making it generally much more stable to begin with
05-15-2019, 08:39 AM
#8
The difference with a Piper Cherokee is it's a low wing aircraft that needs that dihedral to be stable in level flight. A high wing design doesn't need anywhere near the dihedral since all of the plane's weight is below the wing, not above it, making it generally much more stable to begin with
You are correct with the high wing VS low wing and the different dihedral requirements between the two. However the topic is the affect dihedral has on aileron response. My post was to illustrate that you could easily go 10 degrees of dihedral without adversely affecting aileron performance.
05-15-2019, 09:06 AM
#9
Aerodynamically speaking, I think it depends on how you look at it. A practiced pilot would consider 10 more degrees dihedral as adversely affecting aileron performance. The more performance you want, the more trending towards instability you want to get, right? It seems as though obrien135 throws one of these "I don`t have a clue" questions out there once in a while to get everyone arguing except him.
05-15-2019, 09:22 AM
#10
I think there is going to be different opinions on this subject simply because we have differnt views on what performance and stability mean. There really is nothing saying that additional dihedral will reduce aileron authority. It will however create a control cross couple. Many of us long time R/C pilots with little to no full scale experience tend to Veiw stability as the airplanes capability to go where pointed and stay on that line. Full scale guys think as stability in term of the airplane being able to somewhat right itself. One trend I see which full scale guys is the misconception that aerobatic airplanes must be less stable, more difficult to fly and are snap/stall happy.
05-15-2019, 11:40 AM
#11
I think there is going to be different opinions on this subject simply because we have differnt views on what performance and stability mean. There really is nothing saying that additional dihedral will reduce aileron authority. It will however create a control cross couple. Many of us long time R/C pilots with little to no full scale experience tend to View stability as the airplanes capability to go where pointed and stay on that line. Full scale guys think as stability in term of the airplane being able to somewhat right itself.
And I tend to agree with much of this due to the fact that, when comparing an R/C to a full sized plane, the weight of the full sized plane is generally going to give it less stability(especially with a low wing design) than an RC due to the higher wing loading and the shifting weight of the occupants and load, including fuel. A full sized plane is also affected by winds more than an R/C due to the larger side area. If you watch a plane flying toward or away from you closely, it won't be pointing the direction it's flying but, rather, it will be crabbing into the wind. This is something an R/C never has to contend with, other than during the final approach to the landing area.
That is not a misconception, other than the being difficult to fly. If you look at the control systems in any of the front line fighter planes used by the US military, you will find they are all routed through a flight control computer due the the aircraft being so unstable that they are almost impossible to fly without said computer. The Extras, Edges, Eagles, etc, that are commonly seen on the show circuit are all also built to be unstable so the planes can do all the stunts that "WOW" the crowds. No one wants to see a plane slow roll when they expect to see a snap roll. A more stable aircraft may perform a roll but the rolls won't be sharp or crisp due to inertia and weight.
05-15-2019, 11:53 AM
#12
Please keep in mind that I am talking about models here. I would gladly offer you the opportunity to fly any of my aerobatic airplanes, especially my Divergent design. If you were to fly any of them you would soon discover just how easy they are to fly and have none of the bad habits you describe. Until then we can just disagree.
05-15-2019, 03:45 PM
#13
In my to responses to your previous post, I was giving the reasons those that actually fly full sized planes think the way they do. They don't understand that an R/C behaves differently than the full sized planes they normally fly do. This is the reason, based on not a small amount of truth, that full sized pilots are usually the worst students when learning to fly R/C and vise versa
05-16-2019, 04:24 AM
#14
Banned
In my to responses to your previous post, I was giving the reasons those that actually fly full sized planes think the way they do. They don't understand that an R/C behaves differently than the full sized planes they normally fly do. This is the reason, based on not a small amount of truth, that full sized pilots are usually the worst students when learning to fly R/C and vise versa
05-16-2019, 11:36 AM
#15
Actually there is an airline pilot I used to know who has a hobby shop and is an associate VP in one of the AMA districts. He may be retired from full scale by now, but I would guess as a rule that full scale pilots who fly r/c are a rarity. You know, kind of a saturation thing. I know that after working on cars all day that it`s not something I like to do for fun in my off hours.
But, when I got into r/c I was working as an A&P mechanic at the local airport.
But, when I got into r/c I was working as an A&P mechanic at the local airport.
05-18-2019, 09:20 PM
#16
Sorry about the question
I do ask some clueless questions, sorry about that. That's because most of the time I am clueless about the sport and I want to learn as much as I can about it. When it was an engineer I asked a lot of questions like that too and it used to really kick people off. But I appreciate the response has it's very informative thank you very much
05-19-2019, 01:36 AM
#17
Banned
I do ask some clueless questions, sorry about that. That's because most of the time I am clueless about the sport and I want to learn as much as I can about it. When it was an engineer I asked a lot of questions like that too and it used to really kick people off. But I appreciate the response has it's very informative thank you very much
The problem comes from people who think they have the only correct answer or people who don't get the answer they want or expect.
05-19-2019, 11:39 AM
#18
I do ask some clueless questions, sorry about that. That's because most of the time I am clueless about the sport and I want to learn as much as I can about it. When it was an engineer I asked a lot of questions like that too and it used to really kick people off. But I appreciate the response has it's very informative thank you very much
05-19-2019, 05:33 PM
#19
As Appowner has suggested, all questions are accepted. One issue with the internet is that everyone is an expert. Be careful who it is that offers the advise you decide to follow. Check up on the experience behind the advise. Look for things like build threads, other threads where they may have offered help to others etc. Some guys write well but lack experience.
05-20-2019, 06:13 AM
#22
Yes it does matter, you are offering advise on aircraft you have never flown on a REMOTE CONTROL site. The OP was asking a question directly related to models. A question that not only requires some flying experience but designing as well. The bottom line in answer to his question is that on a typical sport/trainer airplane there can be up to 10 degrees of dihedral without any real adverse affect on the ailerons. However there can be adverse affects in other areas such as control cross couple. Remember that a model airplane is a bunch of compromises, what can be benificial in one area can be detrimental in another. Knowing the desired capabilities before making changes or implementing design features is usually nessesary.
05-20-2019, 09:38 AM
#23
So you're telling me that I know nothing about aircraft EVEN THOUGH I HAVE DECADES OF AIRCRAFT EXPERIENCE????
Seems to me that having had full sized flight instruction as well as decades of aircraft maintenance and repair should count for something. BTW, I never claimed that I flew any of those aerobatic planes, didn't have to either since it's not needed to understand the basics of aircraft design and operation.
Now, to quote your last post "Remember that a model airplane is a bunch of compromises, what can be benificial in one area can be detrimental in another" doesn't just apply to models. The wing designs used on Boeing jetliners are a compromise of high and low speed efficiency. This meant the wings had to be optimized for flight with speeds into the trans-sonic range yet they needed a high lift design for slow speed operation during take off and landing. To get the required flight characteristics, an airfoil with a fairly thin height was used to keep drag at a minimum yet with enough lift to support an airliner weighing in at over 200,000 lbs. To get the needed slow speed performance, hydraulic retractable slats are used on the leading edge of the wing to increase the wing thickness while hydraulic fowler flaps are used at the rear of the wing to increase wing chord. The use of flaps and slats provide the lift and low speed performance needed for take off and landing, the most dangerous part of any flight. They are also part of a series of trade offs:
Seems to me that having had full sized flight instruction as well as decades of aircraft maintenance and repair should count for something. BTW, I never claimed that I flew any of those aerobatic planes, didn't have to either since it's not needed to understand the basics of aircraft design and operation.
Now, to quote your last post "Remember that a model airplane is a bunch of compromises, what can be benificial in one area can be detrimental in another" doesn't just apply to models. The wing designs used on Boeing jetliners are a compromise of high and low speed efficiency. This meant the wings had to be optimized for flight with speeds into the trans-sonic range yet they needed a high lift design for slow speed operation during take off and landing. To get the required flight characteristics, an airfoil with a fairly thin height was used to keep drag at a minimum yet with enough lift to support an airliner weighing in at over 200,000 lbs. To get the needed slow speed performance, hydraulic retractable slats are used on the leading edge of the wing to increase the wing thickness while hydraulic fowler flaps are used at the rear of the wing to increase wing chord. The use of flaps and slats provide the lift and low speed performance needed for take off and landing, the most dangerous part of any flight. They are also part of a series of trade offs:
- Slats add a weight penalty due to actuators, hydraulic lines and fluid, as well as operating linkages, tracks and switches
- Flaps add a weight penalty due to drive motors, hydraulic lines and fluid, tracks, linkage and switches
- The added weight of the flap and slat mechanisms are something that has to be overcome by the lift generated by them at low speeds or the wing itself at high speeds
- The added weight of these "lift enhancing systems" lowers the amount of weight the plane can actually carry, making the use of larger wings a requirement or, conversely, removing seats or limiting the amount of cargo that can be carried to keep the plane within its weight and balance limits
Last edited by Hydro Junkie; 05-20-2019 at 09:47 AM.