So, I'm trying to make a small (Simple) Early Fighter Jet kind of thing, any Tips?

quorneng

Master member
You are likely to find that the attributes for slow flying, light weight and a generous broad chord wing area, are not conclusive to a good glide ratio.
As an EDF has limited thrust so what is important is the plane's weight. For a given configuration the power to fly is directly proportional to its all up weight. It may not glide well but it will fly slowly when under power.
Any chance of a picture?
 
Also, no intakes, and the tail is probably too small


WIN_20250116_15_58_31_Pro.jpg
 

quorneng

Master member
For the size of the fuselage, does it have to b e that big to house the EDF? I would make the wing chord broader by 50% and the fin and tail plane twice the area.
A square "box" fuselage, particularly at the rear, has considerable aerodynamic influence some of which can counter what the wings and tail are trying to do. For the "gentle" flight characteristics mount the wing on the top of the fuselage.
Just my suggestions.
 

telnar1236

Elite member
P-80 inlets are actually going to be pretty difficult to model at all accurately on a foamboard RC model. They have some pretty complex contours and are in general too small for an appropriate size fan unless you're building fairly big and very light. Probably, the best bet is to just stick some inlets on the side. You can taper the front of the fuselage a bit to help give it more inlet area while not needing to leave the slab-sided fuselage behind if you're worried about looks. Another option is to just cut a giant cheater inlet in the bottom of the fuselage - you might have a slower plane but the EDF will get plenty of air and it's easy to do.
1737332248840.png

Also, like Quorneng is saying, the fuselage looks a bit big. A high mounted wing might help a bit, but by the time you get to flying a jet, you should also be able to handle a low mounted wing with some dihedral like on a P-80. One risk of going to a high wing is that the horizontal stabilizer will be in the wake from the wing which can on occasion cause some odd behavior, though for most designs, it's fine. Still, I would recommend moving the horizontal stabilizer to the bottom of the plane if you move the wing to the top. The size of the horizontal stabs is a bit on the small end, but honestly looks fine.
Also, like Quorneng said, most EDFs glide badly from a hand launch, though some do better once they're flying at speed - the wings just aren't made for that.
 

quorneng

Master member
short_nathan
Bear in mind that compared to a similar thrust prop installation an EDF is heavy and consumes more power so also needs a bigger heavier battery. The result is an EDF version of a plane will fly faster than a prop.
To make an EDF fly at the same speed as a prop you are going to have counter its extra weight by making the airframe lighter and/or bigger so the wing loading is similar to a prop version however if you are using the same basic foamboard material "bigger" is bound to end up heavier.
What I am trying to show is that unless you can use lighter materials you will have to accept that due to the extra weight involved an EDF will fly faster than if it were prop powered particularly if you add ducting to the EDF inside the fuselage.
 

L Edge

Master member
@short nathan

You state that your hobby is expensive, your budget is tight. Your goals are to design planes that can be enlarged to EDF's when your ready to shift to flying jets. Your beginning to understand your 2 designs need a lot of improvement. Many forum members are offering you good points to remember which you need to learn. Suggest you keep adding these points to your new designs and let the forum members review your modified design.

To me, getting to fly EDF's should come before you design your own. Your problem is money. If you buy a 5 bladed 64 mm EDF($40), an ESC($23) and have/buy a 1300 3S battery($25ish) , you could start to fly. From there, I have use the cheap system (bought more) and fly F-111, Warthog, SR-71, and DarkStar. Lots of problems for each to get going in design.

Now add 1 sheet of Adams board and you can learn to fly a jet. Build time 5 hours max. Looks like a jet, heck no, crash it, and your up flying in less than 5. So, it's super light, plenty of thrust to fly fast and throttle back for slow flight, protects the EDF from damage, has dihedral so you can fly in winds and best of all, you can even add landing gear. Like to see you build an F-86. I even learned how not to launch it.

 
@short nathan

You state that your hobby is expensive, your budget is tight. Your goals are to design planes that can be enlarged to EDF's when your ready to shift to flying jets. Your beginning to understand your 2 designs need a lot of improvement. Many forum members are offering you good points to remember which you need to learn. Suggest you keep adding these points to your new designs and let the forum members review your modified design.

To me, getting to fly EDF's should come before you design your own. Your problem is money. If you buy a 5 bladed 64 mm EDF($40), an ESC($23) and have/buy a 1300 3S battery($25ish) , you could start to fly. From there, I have use the cheap system (bought more) and fly F-111, Warthog, SR-71, and DarkStar. Lots of problems for each to get going in design.

Now add 1 sheet of Adams board and you can learn to fly a jet. Build time 5 hours max. Looks like a jet, heck no, crash it, and your up flying in less than 5. So, it's super light, plenty of thrust to fly fast and throttle back for slow flight, protects the EDF from damage, has dihedral so you can fly in winds and best of all, you can even add landing gear. Like to see you build an F-86. I even learned how not to launch it.

What about a pusher prop FT Viggen? I have just enough leftover electronics from failed builds.
 

Mr Man

Elite member
Maybe you could try peeling the paper off the under side of parts, that would really bring your weight down.(not the wing of course.)
 

quorneng

Master member
A bit of showing off but If you can build light enough even a hand launch becomes redundant.
Low power 55mm six blade EDF powered by a 20c 1800mAh 3s.
No paper, carbon or wood just 5mm XPS foam sheet.
Note the wing root intakes and exhaust are structurally important as apart from feeding the EDF they greatly increase the wing root strength.