Help! Seeking build advice: First-ever airframe build (Long-endurance pusher)

[bssman]

Hi everyone,

My name is Nathan. I’m new to the forum and currently starting a project to build a custom fixed-wing pusher drone. My primary objective is to achieve long-endurance flight, but I am at the initial planning stages and would value the input of this community.

To provide some context: I am an engineer by trade and am very comfortable with electronics, flight dynamics, and robotics. However, I have no prior experience building airframes, and this will be my first time working with foam board. I am eager to learn the best practices for structural design, hinges, linkages, and material handling specific to scratch-building.

I currently have a 3S 5200mAh 60C LiPo on hand. I am conscious of the weight penalty this battery imposes, and I want to ensure I don't build an airframe that is either over-loaded or structurally insufficient for a first-time builder.

Could I get your thoughts on the following?

1. Airframe/Plan Recommendations: Are there proven, beginner-friendly foam board plans that can handle this battery weight? I’m looking for a robust design that is forgiving to build and fly.
2. Power System Efficiency: Given the 3S setup, what motor KV range and prop size would you recommend to optimize for endurance/efficiency?
3. Construction & Setup: Since the motor will be at the rear, do you have any specific "lessons learned" regarding maintaining the Center of Gravity (CG) with a heavy battery in the nose, or structural reinforcement tips for a first-time builder?

I appreciate any guidance you can offer as I embark on my first build.
Thanks in advance for the help!

 

[LitterBug]

What kind of time, speed, payload, and distances do you want/need to accomplish? There will be trade-offs and knowing these parameters will help define the power and airframe. For Endurance rather than all out speed, consider batteries with 21700 cells. The energy density is higher than lipo (lighter), the cells are more durable, but the maximum current rating is usually less. I have Panasonic cell batteries that are 5000mah 45C. As you go up in C rating, the capacity drops. (Tradeoffs).

 

[tomlogan1]

Hi everyone,

My name is Nathan. I’m new to the forum and currently starting a project to build a custom fixed-wing pusher drone. My primary objective is to achieve long-endurance flight, but I am at the initial planning stages and would value the input of this community.

To provide some context: I am an engineer by trade and am very comfortable with electronics, flight dynamics, and robotics. However, I have no prior experience building airframes, and this will be my first time working with foam board. I am eager to learn the best practices for structural design, hinges, linkages, and material handling specific to scratch-building.

I currently have a 3S 5200mAh 60C LiPo on hand. I am conscious of the weight penalty this battery imposes, and I want to ensure I don't build an airframe that is either over-loaded or structurally insufficient for a first-time builder.

Could I get your thoughts on the following?

1. Airframe/Plan Recommendations: Are there proven, beginner-friendly foam board plans that can handle this battery weight? I’m looking for a robust design that is forgiving to build and fly.
2. Power System Efficiency: Given the 3S setup, what motor KV range and prop size would you recommend to optimize for endurance/efficiency?
3. Construction & Setup: Since the motor will be at the rear, do you have any specific "lessons learned" regarding maintaining the Center of Gravity (CG) with a heavy battery in the nose, or structural reinforcement tips for a first-time builder?

I appreciate any guidance you can offer as I embark on my first build.
Thanks in advance for the help!

Did a similar project years ago. 24 inch fuselage of PVC followed by 30 inches of 3/4 inch wooden dowel. 48 inch foam core wing. 2x3530 1700kv motors. 4 9 gram servos. 5000 mah 3s battery. Used for combat but flew very well and had very short takeoff capabilities.

 

[bssman]

What kind of time, speed, payload, and distances do you want/need to accomplish? There will be trade-offs and knowing these parameters will help define the power and airframe. For Endurance rather than all out speed, consider batteries with 21700 cells. The energy density is higher than lipo (lighter), the cells are more durable, but the maximum current rating is usually less. I have Panasonic cell batteries that are 5000mah 45C. As you go up in C rating, the capacity drops. (Tradeoffs).

"Thanks for the feedback on 21700 cells. To help define the airframe:

• Time: I’m aiming for 30+ minutes of flight.
• Speed: I’m prioritizing cruise efficiency over high-speed performance.
• Payload: Minimal for now—essentially just the FPV system and the battery itself.
• Distance: I’d like to keep it within a 5km range for the initial testing phase."

 

[bssman]

Did a similar project years ago. 24 inch fuselage of PVC followed by 30 inches of 3/4 inch wooden dowel. 48 inch foam core wing. 2x3530 1700kv motors. 4 9 gram servos. 5000 mah 3s battery. Used for combat but flew very well and had very short takeoff capabilities.

"Thanks for sharing that! That sounds like a really rugged design, but since this is my first-ever build, I think a PVC/dowel hybrid might be a bit too advanced for me right now.

I'm going to stick to an all-foam-board build to keep things manageable. Based on that, would you recommend a specific Flite Test trainer plan that is sturdy enough to hold my 5200mAh 3S battery without being too difficult for a beginner to put together?"

 

[LitterBug]

I have been flying a Strix StratoSurfer on 3S 4200 packs for years. I can easily acheive 20-30 minutes of flight on those packs with a Sunnysky 2212 kv2400 and a 6x4.5 inch prop. a moderate cruise vs flying fast is key to endurance. Not exactly what you are looking to design, but a good comparison. I have not yet flown it with the 21700 packs yet. On a smaller scale, the strix nano goblins can easily reach 45-60 minutes of flight on a 3200mah 2s 18650 pack. i run a 4.1x4.1 apc pusher prop on these with a variety of small 4000kv in the 14xx -16xx size motors. I fly mostly FPV, but also fly LOS and do plain old PWM RXes and various flight controllers too.

Oops on the one prop.....

These can be flown sub 250g

 

[TEAJR66]

See if this is along the lines of what you are looking for.

 

[bssman]

View attachment 259134
I have been flying a Strix StratoSurfer on 3S 4200 packs for years. I can easily acheive 20-30 minutes of flight on those packs with a Sunnysky 2212 kv2400 and a 6x4.5 inch prop. a moderate cruise vs flying fast is key to endurance. Not exactly what you are looking to design, but a good comparison. I have not yet flown it with the 21700 packs yet. On a smaller scale, the strix nano goblins can easily reach 45-60 minutes of flight on a 3200mah 2s 18650 pack. i run a 4.1x4.1 apc pusher prop on these with a variety of small 4000kv in the 14xx -16xx size motors. I fly mostly FPV, but also fly LOS and do plain old PWM RXes and various flight controllers too.
View attachment 259135
View attachment 259136
Oops on the one prop.....

These can be flown sub 250g

That comparison is super helpful, thanks! Seeing what you get out of the StratoSurfer helps me set a realistic benchmark for my own scratch-build.

It’s interesting to see the flight time difference between your cruiser setup and the Nano Goblin. It really drives home the point about prioritizing a moderate cruise speed. Since I’m starting my first foam-board build, I’ll definitely be focusing on getting the airframe trimmed for an efficient cruise rather than speed.

Do you have any general advice on how you 'tune' your planes for that efficient cruise? Are you mostly just using 'feel' to find the right throttle, or are you relying on OSD (On-Screen Display) telemetry to monitor your current draw (Amps) in real-time? Thanks.

 

[bssman]

See if this is along the lines of what you are looking for.

Exactly. I have watched it a couple of times. Thanks a lot.

 

[LitterBug]

That comparison is super helpful, thanks! Seeing what you get out of the StratoSurfer helps me set a realistic benchmark for my own scratch-build.

It’s interesting to see the flight time difference between your cruiser setup and the Nano Goblin. It really drives home the point about prioritizing a moderate cruise speed. Since I’m starting my first foam-board build, I’ll definitely be focusing on getting the airframe trimmed for an efficient cruise rather than speed.

Do you have any general advice on how you 'tune' your planes for that efficient cruise? Are you mostly just using 'feel' to find the right throttle, or are you relying on OSD (On-Screen Display) telemetry to monitor your current draw (Amps) in real-time? Thanks.

All of the above. I have been flying FPV for over 10 years. I have flown various power setups on the nano goblins. When they were first released, they came with a 12A ESC and the 18650 packs would only put out 11A. That was a self limiting setup that forced efficient flight. I later switched to a 20A ESC and batteries that could sustain 25A. Now it could go faster on the same motor and the Motor became the limiting factor on top speed. Under the latter setup, the capacity of the batteries was lower but the max speed was higher, and flight times shorter. (tradeoffs) (still 30-40 minutes) So practical real world flying with different setups. I do use flight controllers and OSD data now. Can track everything the FC gives you. But mostly just ignore the data and fly now. I will be paying closer attention to my Stratosurfer data this summer as I test different props and battery packs.

 

[bssman]

That is a great perspective on how the bottleneck shifts from the battery to the motor. It makes a lot of sense—by upgrading to a higher-capacity battery/ESC, you essentially "opened the door" for the motor to work harder, which naturally trades flight time for speed.

For my first build, I think I’ll take a page from your original Nano Goblin experience and stick to a "self-limiting," efficient setup. My goal is definitely to prioritize that 30–40 minute flight window rather than chasing top speed. I'll focus on learning how to manage the throttle effectively to maximize my endurance, as I'm sure that will be the best way to learn how the aircraft is actually performing in the ai