Of course a plane wouldn't fly without wings, but how the wing is shaped and sized on a park jet design has significant impact on how the plane will fly. I haven't flown any real exotic winged planes like the F-117 or a flying wing like the B-2, but have covered pretty much all the other wing shapes and sizes in my park jet journey thus far.
Here are the four wing types and their characteristics that I have flown and experienced in my park jet career.
- Moderately swept - I often refer to the F-18 as being a "straight wing" plane, but it is moderately swept at the leading edge and essentially a straight trailing edge;
- Delta - planes like the Eurofighter, Rafale and F16XL, all a form of delta wing where the wing shape is essentially a large triangle. These planes are normally single fin tails and have the elevons incorporated in the trailing edge of the wing without benefit of horizontal stabilizers and elevators as on "conventional" jets.;
- Stealth - modern stealth planes like the F-22, Sukhoi T-50 and F-35 have a very unique wing shape, the F-22, T-50 and our NAMC Mig-FA have very similar wing shapes with the horizontal stabilizer almost blending into the wing. One characteristic all the planes in this category that I have flown including the F-35 is that the leading edge sweeps back and the trailing edge sweeps forward, making for very unique look and flying characteristics; and
- Swept wing - in this category I am referring to wings that are fairly aggressively swept rearward at both the leading and trailing edges like the Mig-35, Su-35, F-15 to name a few, although the F-15 does have a more unique trailing edge, they all have very similar wing characteristics. I will discuss this one last in this post as I think this is the most popular and versatile wing in my park jet experience.
The only plane I have experience with having this type of wing is the F-18, however the F-16 has a very similar shape wing, so some of the same characteristics might apply. I took these pictures when I was still testing my most recent F-18 V3 build, hopefully it gives you a good idea of the wing layout.
Although there is considerable wing area, due to it's design, this wing does not handle high wing loading as I mentioned already in part 3 of this series. However, I did find in my most recent build pictured above, that a wing reinforcement plan like this one shown below does make for a very strong, stiff wing, the strongest of all F-18 wings I have built thus far.
With the LERX assisting however, it does make for a stable platform for slow speed and high alpha flying if that is something you seek. I pretty much taught myself high alpha flying with the F-18 V3 and it is one of the most stable high alpha park jets around, flying very scale high alpha when compared to the real F-18.
Overall, good stability and handling characteristics, combined with all the other features of the F-18 V3, this wing shape makes for a good starter park jet in my experience.
I don't have a lot of flights with delta wing planes, they are certainly unique and simple to build, only three servos with rudder. Pitch and roll is elevons only along the trailing edge of the wing. I dug into my photo archives for pictures of the Rafale (a semi profile plane I built from a plan on parkjets.com) and the Parkflyers International F-16XL "Garuda". I wrote a very detailed report on what I learned from the F-16XL here, it actually has what is referred to as a "cranked delta" wing which gives it better slow speed characteristics. Also shown is a recent picture of the RC Powers Eurofighter V5 that I built.
Although most delta wing planes in real life have been pretty fast (F-106, Concorde, etc), I never noticed that delta wing park jets were any faster than others. Even though it is larger with a much bigger leading edge, I would say that the F-16XL was the fastest of the bunch, again, not having the frontal drag of the canards probably helped with this.
Slow speed stability of these delta wing planes is about average, not as good as a straight wing or aggressively swept wing, but better than a "stealth" style wing from my experience. The "cranked" delta wing of the F-16XL has the best slow speed handling as the wing was specifically designed to try and blend the improved high speed of a delta while still allowing for good slow speed maneuvering and stability.
Simple setup with three servos, but limited for advanced aerobatics, not very good for any sort of high alpha, although I have played around a bit with flaperons for slower speed. Roll rates are slowed by the large wing, so roll input in the elevons needs to be relatively high to get crisp roll rates, but pitch rates are quite good as the elevons have a much longer span than they do on non-delta planes.
Wing loading with this style wing is good, although none of the planes above were over 22 oz, but the wing was very strong and solid, so could probably handle more weight if you really wanted a faster delta wing park jet by adding a more powerful motor setup.
"Stealth" style wings
The stealth wings and profile of planes like the F-22, T-50, NAMC Mig-FA and F-35 are very unique and have their own unique set of characteristics.
The F-22, T-50 and Mig-FA can handle a pretty heavy wing loading without too much trouble, the F-35 not as much. All of them because of their very "thin" frontal profile from top to bottom or completely flat bottoms in the case of the F-22 and F-35 have extra lift (perhaps about 15% more) due to this extra flat surface. This can make the plane feel lighter than it is, but can also cause the plane to want to "zoom" at higher speeds, so trimming the plane properly or shimming the motor down can sometimes be needed to stop the plane from wanting to climb on it's own at full throttle.
To make the plane more stable at slower speeds as we started to learn with the Mig-FA, one of the biggest secrets is to get the weight distribution (ie the battery) as low as possible. This was further proven with the RC Powers F-22 V5, even though their design called for the battery to be low, I lowered it even further and it is the most stable, well behaved and forgiving F-22 I have ever flown.
What I found with extensive testing of the Mig-FA is the stealth style setups like the Mig-FA, F-22 and T-50 are very prone to adverse yaw at slow speeds. In other words, as the plane gets slow and you try to give it roll input to turn one way, it will actually yaw quite aggressively the other way, normally after almost reaching stall. This can be quite catastrophic if you are low as you need some altitude and to be very quick on the throttle to get it to recover before it starts spinning opposite to the direction you wanted to turn.
RC Powers has touted the F-35 V2s and V3s and good trainers, I have never flown the V3, but I found the V2 to be a bit of a challenge as a trainer, not just because of the wing shape, but other issues I will discuss further in later articles of this series. I would not recommend any of the other stealth style planes as a plane to tackle early on either although the F-22 V5 is one of the best stealth style planes I have ever flown with the couple of mods I made to it. These type planes are perhaps good for a third or beyond park jet as they can be tricky to fly for someone just starting off.
There are a couple of tricks to try if you do want to fly slow or attempt high alpha. Flaps/flaperons work the best as lift aids. They help deflect "dirty air" away from the elevons rather than using spoilers/spoilerons which lift the dirty air and them dump it on the elevons, making the plane very unstable and hard to control at slow speeds.
But at 50% throttle and higher, stealth style planes are very happy, stable and quite aerobatic, especially with full controls. Even without the computers, you can do some really good scale aerobatics with most of them and they are very stable as they glide in to land as long as you don't try to get too slow and just let the plane establish it's own sink rate.
In this category, I am referring to wings that are swept fairly aggressively at the leading edge and trailing edge like the Mig-29 and Su-27 family of airplanes and to a certain extent the F-15. For this part of the discussion, I will refer to the Mig and Su wings primarily as about 50% of all my park jet flights over time have been with Mig-29 and Su-27 style planes that rose from these two iconic fighter jets. Here are pictures of the NAMC Mig-35B on the left and the Parkflyers International Su-35 on the right.
The two planes above have overall quite similar speed envelopes from quite slow to quite fast. You will notice a difference in how the LERX are shaped, the Mig's flare away from the nose, making the LERX and "shoulders" of the plane larger which does help the plane fly very smooth, but compared to the Su, a little less snappy in the pitch and roll. With it's LERX flared in more, the Su responds more quickly and aggressively in the pitch and roll without the extra surface area in the way, so these are considerations to keep in mind between the two wing shapes. Both these planes are quite capable of very scale maneuvers and if you watch videos of the real planes on You Tube, you will note that the Su does respond more quickly and aggressively in the pitch and roll.
Either way, this wing shape as I mentioned is the most versatile from the stand point of their speed and stability envelopes. If you want a really fast plane with the potential for lots of aerobatics, this wing shape is the best to choose in my experience, but it will still allow for good slow flying and rather forgiving characteristics, with the Mig wing shape being slightly more stable and forgiving when slow, probably due to the bigger LERX.
So each wing shape has it's strength and weaknesses depending on the flight envelope and performance you seek from your park jet. This is certainly one of the more important considerations to keep in mind when selecting a park jet as the wing shape and size is so key to the plane's overall foundation of performance.
In the next article in this series, I will discuss the importance of motor location in selecting the park jet that is right for you.