It's not optimised.
In case of designs like these there are so many constraints like wings should fold, be short, decrease flutter so it becomes absolute necessary to optimise each and every bit of the design. American JSOW use lift generated from body to aid the wings.
There is only (common) one way to increase the lift form a wing; increase its area. Which can be done by either lengthening it or widening it.
Now coming to what's wrong
- the wings have way less area than the weight of the projectile demands; this is the reason why it bends upwards. It's not intentionally made dihedral; it's just struggling to hold the weight.
- the wings are not stiff enough; bombs like Spice 1000 also use long thin wings but you won't find this curvature on them. So in case of sudden maneuver the wing can snap.
- the effective lift gets reduced. Let's assume a wing generate 10kg of lift and doesn't bend.
View attachment 197114
In this case when you'll resolve that force into its components then the vertical component will have 10kg of force and horizontal will have 0kg of force.
Now you bend that wing.
View attachment 197113
Now upon resolving the force gets divided into say 8kg as vertical component and 2kg as horizontal. But this horizontal component of force is doing nothing except cancelling each other from each wing. So the effective lift now becomes just 8kg.
- commercial aircrafts also suffer from bending of wings but to counter this they already have a longer and tapered wing. So even after wasting some amount of lift it has sufficient to fly.
Ab khush Chacha!?
I was also thinking to give a technical answer but don't know why this line "The scientists at DRDO definitely know more than you and me, let them take care of the bomb's aerodynamics and structural rigidity." felt bit too weird to answer in that way.
Just imagine one fine day Prasad Bansod coming up with an idea to make a sub-machine gun based on Glock. And the very next day ditching it thinking if DRDO has not yet developed something like this then it must be a dumb idea.
Would we had got the opportunity to praise ASMI?
Didn't want to bite, but please empathise as I actually took the time, effort and attention to read your whole article.
1. The only way to get more lift is to increase wing area. If the wings don't provide enough lift, they bend upwards etc.
So, lets say the wing's S doesn't generate the required L at the current Cl and V. What will happen is not that you will have more delta-y, rather your aircraft will just loose altitude. If you tried to solve your delta-y problem by making the wing area larger (increasing span is better than chord for this, better AR), you will still have as much delta-y if not more because delta-y is proportional to span.
Summary: Your problem is your bomb still weighs 1000kg and your wing is not STRONG enough - you would hence add more spars, or reinforce the wing box. Increasing its area will not decrease delta-y. So basically, you are right in your second point.
2. Wings are not stiff enough
That would be the only reason for UNWANTED deflection or god forbid unwanted dihedral (basically your wing broke). We can get into whether is intentional or a failure of the wing later because it would make more sense after understanding dihedral and deflection.
Wing Deflection vs Dihedral Wings
3.
commercial aircrafts also suffer from bending of wings but to counter this they already have a longer and tapered wing. So even after wasting some amount of lift it has sufficient to fly.
You are mixing up deflection with dihedral - commercial planes have both on purpose, they don't suffer from it.
Deflection An A380 tip deflection is like 12 feet or something and very much designed into the structure. When you have gusts, crosswinds turbulence etc. you want your wing flapping to absorb that motion than transfer the loads to the fuselage.
This by the way has NOTHING to do with dihedral, commercial planes have that too (even when tip deflection is 0, there will still have a very high dihedral angle)
4.
Why Dihedral? You then proceed to tell me why dihedral is bad for lift basically. With diagrams that show that the sin cos split of the dihedral takes away some lift.
Yes, you will loose some lift with dihedral wings. You also loose lift with swept wings. The best wing for best lift is a boring old straight rectangular wing.
So why do we make dihedral wings in the first place? Did you think its just an unwanted effect? It is very much an intended effect. Its all about roll stability or lateral stability.
- A positive Dihedral angle > increases roll stability,
- A negative Dihedral angle > decreases roll stability. (Anhedral)
Roll stability: if a flying body is perturbed in the roll direction, it will have a tendency to come back to being upright. Caused by high mounted wings, dihedral wings, rear sweep (very minor effect)
Roll instability: if its perturbed in the roll direction, it will continue to spin even more. Caused by low mounted wings, annhedral wings, forward seep (very minor)
Some examples:
C-17 has annhedral wings, because the high mount and heavy loads it carries makes it difficult to roll the plane - so they had to counter that with an anhedral.
Commercial Aircraft have dihedral, because their low mounted wings (driven by ease of access to engines and packing the landing gear) causes lateral instability, which needs to be stabilised.
A Cessna, and some gliders, have both high wing and dihedral - because you just want stability at this point for ease of flying and safety. Passive self correction is what you want.
Glide bombs: You want to control rolling on separation, and even during glide to have the most stable flight path with minimal corrections to counter cross winds, turbulence, gusts and other non linearities. Almost all have high mounted wings which further tells you how they are thinking. Wether you want a dihedral on top of that or want to rely on software control - thats a choice.
In my opinion, they might have gone this way because their x-tail surfaces are quite small with a horrible aspect ratio. Most glide bombs have bigger X tails with decent aspect ratio - however its understandable if this is an add on kit and you can't change the tails on the body.
S = wing area
Cl = coefficient of lift
V = velocity
W/S = wing loading
AR = aspect ratio
delta-y = wing deflection at tip
chord = wing width
span = wing length