Sub 250g depron racer

[The Fopster]

I’ve been refining a design of a very easy to build bank and yank racer. I’ve got one running an 1806 drone motor with a 6x3 prop. With an 850mAh three cell battery it’s 247g ready to fly, and is a fun little sport flyer. We’re planning some budget pylon races at our flying club using them for some cheap fun. I’ve got a more spicy version as well - it’s got a 2207 drone motor and a 5.5x5.5 prop with a 1300mAh 3 cell. That one’s a rocket!
Construction is very simple using depron (as lightweight foamboard is hard to get in the UK at the moment). I’m planning to try selling plans as I’m currently ”not working” (redundancy…). Anyway - had a first attempt at chase footage with a clubmate at the weekend. It was very blustery and I was flying the 247g version but we managed to get some usable footage. No doubt we will get better with practice!

 

[Mr NCT]

That's a nice smooth flying plane, good job.

 

[danskis]

Nice plane and a great chase video! My compliments to the pilots. I much prefer a good chase video over an FPV any day.

 

[L Edge]

I’ve been refining a design of a very easy to build bank and yank racer. I’ve got one running an 1806 drone motor with a 6x3 prop. With an 850mAh three cell battery it’s 247g ready to fly, and is a fun little sport flyer. We’re planning some budget pylon races at our flying club using them for some cheap fun. I’ve got a more spicy version as well - it’s got a 2207 drone motor and a 5.5x5.5 prop with a 1300mAh 3 cell. That one’s a rocket!
Construction is very simple using depron (as lightweight foamboard is hard to get in the UK at the moment). I’m planning to try selling plans as I’m currently ”not working” (redundancy…). Anyway - had a first attempt at chase footage with a clubmate at the weekend. It was very blustery and I was flying the 247g version but we managed to get some usable footage. No doubt we will get better with practice!

With the rocket version, does it do tight turns around pylons?

 

[The Fopster]

With the rocket version, does it do tight turns around pylons?

It should with a better pilot than me - I'm struggling to just keep it under control! I just got back from the field after flying it with my bike GPS speedometer stuffed into the fuse on top of the battery. Max speed was 82mph. At that speed I'm going to need a lot of practice before I'm doing tight pylon turns! The sub 250g version with the 1806 motor maxed out at 56mph but there was a decent amount of wind assist on that flight. Cross wind it was more like 45mph - that's more likely to be my start point for a pylon race class!

Here's the GPS for the faster one.

 

[L Edge]

It should with a better pilot than me - I'm struggling to just keep it under control! I just got back from the field after flying it with my bike GPS speedometer stuffed into the fuse on top of the battery. Max speed was 82mph. At that speed I'm going to need a lot of practice before I'm doing tight pylon turns! The sub 250g version with the 1806 motor maxed out at 56mph but there was a decent amount of wind assist on that flight. Cross wind it was more like 45mph - that's more likely to be my start point for a pylon race class!

Here's the GPS for the faster one.


View attachment 235314

The key to pylon racing is 50% proper setup of the plane and the other 50% is pilot skill. I have some tricks for the plane for the CG, trimming it and how to set up the racer for dynamic turns that allow smooth turns.
Crosswinds and dirty air can help/hinder you depending if you are in front/behind the other racer. Many other tricks to get you out in front.

My son and I starting off racing at 135 mph class and moved up to 180/200mph. A 10 lap race lasted 1:05 minutes.

 

[The Fopster]

If you fancy sharing any set up tips I’d love to hear them. If I can get 75% of my performance from the plane that lowers the pilot skill part to 25%! 🤣

 

[L Edge]

If you fancy sharing any set up tips I’d love to hear them. If I can get 75% of my performance from the plane that lowers the pilot skill part to 25%! 🤣

Will do. Is the plane equipped with rudder control?
Are you allowing things such as rounding off leading edges of wings, rudder, elevator?

 

[Piotrsko]

Obvious comment: he only needs to be faster than the others around the course. Looks a bit overly twitchy but it was windy in the video

 

[The Fopster]

Obvious comment: he only needs to be faster than the others around the course. Looks a bit overly twitchy but it was windy in the video

It was indeed very blustery, but I’ve also moved the CG forward another 3mm which has also removed the pitch sensitivity. I’ll get more footage at some point!

 

[The Fopster]

Will do. Is the plane equipped with rudder control?
Are you allowing things such as rounding off leading edges of wings, rudder, elevator?

The plane doesn’t have rudder - I could probably fit one and still be under 250g but it would be close! I do have some mechanical aileron differential so the will be a little proverse yaw with aileron. Leading edges are rounded off, but not very precisely. If there’s a specific profile chances are I’m not using it! The “rules” will be the planes need to stick to the outline of the plans, but tweaks like leading edges etc. are allowed…

 

[Piotrsko]

Dont need a moving rudder for basic bank and yank style of flying, but it does need directional stability.. I didn't see a directional instability in the video and the cg movement probably removed a lot of the twitchy I saw.
You want arrow like straight flight until you need to turn; Wind or no wind and with very little control surface movement from the sticks. Ideally, you'd fly using the trim buttons. Next issue will be flutter but you may not get there

 

[L Edge]

As far as rudder movement, no problem, you can glue on a trim tab if need.

Looking at the plane in building, get your tools out for this makes it easy to trim in flight.

0) Is your fuse twisted or curved ?
1) Find center of wing. Balance it and add/subtract weight to get it to balance by itself.
2) Put wing into fuse saddle so it is perpendicular.
3) Install elevator so it is perpendicular to fuse(same as wing). The saddle of the elevator fuse needs to be the same angle as wing.
4) Rudder needs to be perpendicular and not skewed(c/l of fuse).
5) Need to measure from leading edge end of wing tip to to elevator end of wingtip on each side. You need to be as close as possible to about a 1/64" dimension. Basically, in 3 axis, your plane parts need to be same, parallel, or perpendicular to each other.
6) Motor is put on perp in both axis.

Check your present plane
The eye is very accurate, so stand behind your plane, eyeball elevator onto wing, is the gap the same? Rudder perpendicular. The more things are symmetrical, (not a twisted wing or bent wing,etc) the better it flies. Develop a method so that every time the wing is put on, it is the same position.

We reached the point that I had a master builder do our Formula 1's. He uses a big marble table and mm tools to jury rig to get it perfect before it was put together. Made dialing in a lot easier. That's it's for today.

Will cover next time what to look for for in setting up plane in flight.

I use 3 of these to check axis and gluing 90 degrees.



Are props all going to be the same or do you have the choice in 6"?

 

[The Fopster]

Dont need a moving rudder for basic bank and yank style of flying, but it does need directional stability.. I didn't see a directional instability in the video and the cg movement probably removed a lot of the twitchy I saw.
You want arrow like straight flight until you need to turn; Wind or no wind and with very little control surface movement from the sticks. Ideally, you'd fly using the trim buttons. Next issue will be flutter but you may not get there

If I’m going fast enough for flutter to be a problem I’ll be celebrating! With the CG forward I’m pretty close to that arrow like behaviour you’re describing. I’m going to have a really low rates setting when I fly this weekend to see if I can get closer to that “flying off the trim buttons” you’re describing.

 

[The Fopster]

As far as rudder movement, no problem, you can glue on a trim tab if need.

Looking at the plane in building, get your tools out for this makes it easy to trim in flight.

0) Is your fuse twisted or curved ?
1) Find center of wing. Balance it and add/subtract weight to get it to balance by itself.
2) Put wing into fuse saddle so it is perpendicular.
3) Install elevator so it is perpendicular to fuse(same as wing). The saddle of the elevator fuse needs to be the same angle as wing.
4) Rudder needs to be perpendicular and not skewed(c/l of fuse).
5) Need to measure from leading edge end of wing tip to to elevator end of wingtip on each side. You need to be as close as possible to about a 1/64" dimension. Basically, in 3 axis, your plane parts need to be same, parallel, or perpendicular to each other.
6) Motor is put on perp in both axis.

Check your present plane
The eye is very accurate, so stand behind your plane, eyeball elevator onto wing, is the gap the same? Rudder perpendicular. The more things are symmetrical, (not a twisted wing or bent wing,etc) the better it flies. Develop a method so that every time the wing is put on, it is the same position.

We reached the point that I had a master builder do our Formula 1's. He uses a big marble table and mm tools to jury rig to get it perfect before it was put together. Made dialing in a lot easier. That's it's for today.

Will cover next time what to look for for in setting up plane in flight.

View attachment 235392

I use 3 of these to check axis and gluing 90 degrees.



Are props all going to be the same or do you have the choice in 6"?

I think it’s built pretty straight. The design is done so that everything is positioned relative to the build table, and I built it on a granite kitchen worktop. I dont have the capability to build any more accurately - at least not a small plane in depron. I’ve no doubt others could do better, but I’m maxed out!
Prop wise I’ve tried three blade drone props which were very quiet but lacked punch, and the 6x3 two blade I’m now using. It’s the best I’ve tried so far, but I’ll experiment further.

I’ve got a second one built with a 2207 motor. That one is quite a bit heavier as it has a wooden wing spar and is running a 1300 mAh 3 cell. So far the best prop on that one is a 5.5x6.5, and that one is doing over 70mph and over 80 with a little wind assist. I like the purity of the simple light weight one better, plus at 80mph it’s a small plane and gets a long way away very quickly! It’s a lot of fun though, and good practice as I just built my first EDF so I need to get accustomed to the speed!

 

[L Edge]

Pose the second issue for you to think out and give me your assessment. Assume 2 pylons with your plane doing 60mph(88ft/sec) and a 30 degree at say 20mph(29.3 ft/sec.(high number so see what is going on).

Get a 8 1/2 by 11" paper and put 2 pylons (small dot)s with arrows over the dot with the cross wind coming in 30 degrees (2 o'clock).

Now mentally do a run once around with no wind and then describe to me a once around with the wind and how you will correct.


1 describe corrections for takeoff and upwind straight
2) describe upwind left turn corrections
3) describe downwind straight
4) describe downwind left turn

Then you need to practice at 2 crashes high in windy conditions to learn how to correct going around that mental pylon consistently.
Practice, practice.

 

[The Fopster]

Pose the second issue for you to think out and give me your assessment. Assume 2 pylons with your plane doing 60mph(88ft/sec) and a 30 degree at say 20mph(29.3 ft/sec.(high number so see what is going on).

Get a 8 1/2 by 11" paper and put 2 pylons (small dot)s with arrows over the dot with the cross wind coming in 30 degrees (2 o'clock).

Now mentally do a run once around with no wind and then describe to me a once around with the wind and how you will correct.


1 describe corrections for takeoff and upwind straight
2) describe upwind left turn corrections
3) describe downwind straight
4) describe downwind left turn

Then you need to practice at 2 crashes high in windy conditions to learn how to correct going around that mental pylon consistently.
Practice, practice.

I will be flying on Sunday - I’m going to have my first attempt at flying the imaginary pylon course. I’ll use the slower plane with the tiny motor so about 40mph, but still more fast thinking than I normally do flying. Can’t imagine how much practice it takes to do it at 60mph or much higher. 😳