One Off Racer FrSky test plane

[Tench745]

Edit: 11/10/2019
Version 3 plans available.
https://forum.flitetest.com/index.php?resources/mcb-racer.90/


I'm breaking a promise to myself; I'm posting another project.

After FFEast I was incredibly burnt out. Months of working on the Spirit of St Louis left me pretty tired. Losing my Cafe Racer to a radio failure at the event left me even more disheartened and questioning my choice of Spektrum and Orange receivers. A week later my versa-spear refused to pull out of a loop and stripped a servo. Accelerated stall, my fault. I was not confident in my radio or abilities. The choice in my mind was, do I improve my equipment, or, basically, give up.

I opted to buy a Taranis X9D+ and X8R receiver.
Not willing to risk any of my current models and wanting to tackle something simple after the Cafe Racer and Spirit builds I decided to tackle one of my favorite doodles.


The first iteration didn't work so well. I'm not entirely sure why. Test flight from a hand launch started and ended with a simultaneous uncontrollable climb and roll to the left, totaling the plane.
The wing was made thinner for a lower coefficient of lift which will hopefully reduce the climb tendency. I also moved the wing from a mid-wing configuration to a low-wing for ease of construction.



After building Version 2 I realized that the tapered wing led to some wash-in at the wingtips. I trimmed the ailerons up to help negate this error during testing. My working drawings have been updated to hopefully remove the underlying cause.



Of course, now I had a brand new Taranis and 8ch RX to play with, so I added flaps and played around with slowed flap deployment, flaperons, crow, etc. I wanted to add retracts, but didn't feel like spending any more on a prototype.


Completed V.2 next to the stripped V.1


V.2 Has not yet flown. I didn't have the weather before winter hit and Spring is still a ways off here in NY. So, despite my promise not to share another project before it had flown, here it is.

Incidentally, I'm looking for a naming scheme for my models, something to brand them as mine like Flite Test has FT and Nerdnic has NN. I was thinking MM for McBurney Manufacturing, but that gets confusing with Mountain Models...

 

[PsyBorg]

MacDonalds has Micky D's you could play off that and say the Micky B Racer or like the MickyBee P40 v2.3 or what ever model and revision plane you come out with. Then use some kind of Bee logo instead of golden arches. (Would not suggest using same bee as Beta Flight though.)

 

[DamoRC]

Looks sleek - any worries about the low profile v-stab?

DamoRC

 

[Tench745]

Looks sleek - any worries about the low profile v-stab?

DamoRC

Oh, I have all kinds of worries. I think the whole empennage is undersized, but was going to give it a shot anyway.

 

[RMDC]

It looks like it's going to be a fun little bugger. I'm eager to see all those channels in action, particularly if you do end up adding retracts later. I'm looking at buying an 8-channel receiver myself to take advantage of my Q X7's capabilities in the future.

 

[rockyboy]

Glad to see you back in the building side again!

The look and proportions of that are very similar to the Caudron and Goon - and I think both Josh and I found that we needed to increase the emgennage size about 15-20% over scale to help tame the beast

 

[Tench745]

I posted it to the FT Fans page but forgot to mention it here. This plane flew! I took it out to my second choice flying field (the first was ironically being mowed) and tried to do a ROG takeoff, but the grass was too long, so I decided to try a hand launch.
This plane seems to either want a lot of speed on takeoff or something was terribly off in the design. It flew straight ahead, but it was a struggle to keep wings level. After a few seconds of trying I lost the fight; it rolled left and the nose skidded into the ground. Things were a bit crunched, the forward turtledeck was ripped clear off and the landing gear had cleanly removed itself, but I was able to stuff the firewall back in place firmly enough to run up the engine without it moving. I thought, "Ah what can it hurt, I've already crashed it" and I tossed it back into the air.
This time she was perfectly stable and controllable. That is, until the firewall broke free and pulled it, rather comically, straight into the ground.
Things got torn up quite a bit, but I glued it back together once more. I'm hoping to do some more test hops with the wheels on. I'm afraid they may either be too draggy, or are turbulating the airflow over the wings. Testing will tell, it may become a belly-lander. I did draw up a slightly larger v-stab, but with how well it flew after the first crash I'm not sure I'll need it. I suspect the first few landings will let me know that too.
I have plans available with both tails drawn if anyone is interested.

 

[PsyBorg]

That looks very similar to a Caudron 460. Maybe once this one meets its end you might wanna give Rockboys design from last years races a shot.

There were several in the actual race and I am sure at least a few others were built once the design was proven and plans finalized.

 

[rockyboy]

Now that I've got another year's flying experience under my belt from when I did the Caudron, I'd suggest adding a bit of washout - raising the trailing edge of the wing by about 3/8" out by the tip should help with the nasty wing dropping stall tendencies. At least it will help keep the ailerons effective in the air long when she is about to stall, which gives a fighting chance of getting her back level

 

[Tench745]

I modified the McB Racer plans a bit.
The wingspan is now 3" longer, moved the gear further ahead of the CG. This should make takeoffs from the grass less likely to nose over. I increased the amount of undercamber at the wingtips and kept the ailerons back from the undercambered wingtip, which should eliminate much of the tip stall characteristics of the first model. I switched to the larger vertical tail and removed the curve I had in the nose to ease building and allow it to take an FT powerpod. I still have to build the new version and test fly it, but if anyone wants to be a beta-builder for me, I wouldn't say no.
I even have an icon for the Taranis.

 

[Tench745]

I spent today building version 2.1 of what I'm calling the McB Racer. (Logo pending)
It works better when you don't accidentally double the chord thickness. :facepalm:
Building another new wing tomorrow with the right spar height.

 

[PsyBorg]

Uhhhh. Ooops?

Save that wing for a different project. Looks like a good starting point for a bomber style 4 engine experiment in my mind anyways.

 

[Tench745]

Uhhhh. Ooops?

Save that wing for a different project. Looks like a good starting point for a bomber style 4 engine experiment in my mind anyways.

Believe me, I really wanted to... but I needed the electronics back out of it.

 

[Tench745]

Build 3 of the McB Racer, as I'm now calling it, is finished. I balanced it up today and took advantage of a calm warm morning to maiden her. I tried my new head-strap camera rig to get some video, but my camera died just after the engine run-up, so I have nothing to share.

Maiden Flight
The grass was very long, so I opted for an underhand launch at about 2/3 throttle. There was a little bit of wing rock as the aircraft wallowed it's way quickly up to flying speed. With a little more throttle, maybe 3/4, the climb-out was quick and manageable.

Even on low rates (30% throws) you get the sense that this is an agile plane; on mid-rates (60%) one may even call it "twitchy," but I think that would be unfair as I had no expo set for the maiden. I did not try high rates (80%) as they seemed unnecessary and ill-advised.

This aircraft NEEDS rudder to fly well, especially as you slow down; I'm glad I enlarged the tail. If you don't keep coordinated in turns and you get slow the plane will drop a wingtip rather suddenly. If you manage to keep coordinated a wallowing motion warns of the approaching stall. This tendency is exaggerated significantly as flaps are deployed.

The aircraft seems rather unstable in roll. If a wingtip lifts, the plane is happy to keep going until it's upside down, but as long as you keep on top of it it is very manageable.

The first flight was about 5.5 minutes before I brought it down to tweak radio settings. I flew throughout the speed range, but did not play with stalls much other than to see approximately what speed to maintain on approach.

Subsequent flights
The second and third flights were made with 30% Expo set for mid-rates on the Elevator and Ailerons which made them sufficiently powerful without feeling touchy. Again, I did not switch to high rates.
On my final approach I let my airspeed decay too far and she started to wallow around, warning of the approaching stall. I am very out of practice and in the heat of the moment I started to push the slider forward to reduce flaps instead of pushing the throttle forward like I meant to. It was a bit of a scramble to keep her from stalling but I managed to get her level before she hit the grass. She skidded sideways a foot or two which folded the right gear under, ending my flights for the day. No other damage occurred as it was a pretty low-energy impact.

Summary:
Finally this airplane flies and I LOVE it! She has a great presence in the air, speeds up quickly and feels right at about 3/4 throttle. She'll hold altitude at about 1/2 throttle, any less and she decends. Speed bleeds off slowly compared to some of my other airplanes; flaps help slow things down quicker, but do require elevator to compensate a noticeable pitching moment.
I wish the grass had been shorter so I could try some touch-and-gos because setting the racer up for a landing and dialing flaps in as she slows is a very satisfying activity.
I have only flown the FT Spitfire in sims, but this plane feels like a sleeker, heavier Spit.
There was a moment when I flew overhead and just fell in love with the presence this plane has when in the air. It is not a beginner's plane by any means, but I think with some dihedral and smaller control throws it would become a good intermediate airplane.

I'm going to look at swapping around aileron and elevator linkages to reduce throws mechanically before the next flight.

 

[DamoRC]

Congrats! Any pics of the final V3 version?

 

[Tench745]

Congrats! Any pics of the final V3 version?

It looks very much the same as V1 and 2. Slightly larger tail and the LG is farther forward.

Now that I know if flies I'll have to decide on some paint!

 

[Tench745]

Congrats! Any pics of the final V3 version?

I finally got around to painting this one. Green is spray paint. Red is 1/4" pin-striping tape; 40 feet for $4 at Autozone. The logo on the tail is printed on transparent label paper. The logo's colors didn't turn out quite as saturated as I wanted, but I've determined that I can just apply another printed label over the top to get the hue I'm after.

I also split the wing and added a few degrees of dihedral to make this a little more fun (easier) to fly.

 

[buzzbomb]

I finally got around to painting this one. Green is spray paint. Red is 1/4" pin-striping tape; 40 feet for $4 at Autozone. The logo on the tail is printed on transparent label paper. The logo's colors didn't turn out quite as saturated as I wanted, but I've determined that I can just apply another printed label over the top to get the hue I'm after.

I also split the wing and added a few degrees of dihedral to make this a little more fun (easier) to fly.
View attachment 146623

Just found this thread. What a great journey with an awesome plane! Really looking forward to video if/when you're able to get it. You never said what you thought about your move to the Taranis. Better, worse, same?

 

[Tench745]

The worst thing about the Taranis is the learning curve you have to climb, but I think it was totally worth it. I went from the DX6i, which is very limited in its abilities, to the powerhouse of customize-ability that is the Taranis. I love the ability to make any thing do or be any other thing.
For example, the DX6i only has two mixes which are limited to specific switches. You cannot program a motor kill switch. The Taranis has more mixes than I can even think of possible uses for. Programming a motor kill switch is a matter of only a few minutes. I almost feel bad that I'm not using more of its capabilities.

The second worst thing has been the fight to get it to communicate properly with my Hobbyzone Champ and other Spektrum recievers. Eventually I will switch out all my receivers for Taranis

I haven't noticed any significant difference in fidelity, power, or crispness versus the Spektrum, so no complaints there. I have, sadly, done very little flying since FF2017.

All in all, I am very happy with it. But I will still hang on to my DX6i for Hobbyking BNF models and buddy-boxing.

 

[buzzbomb]

Thanks for the answer. I moved from a Turnigy 9X to a Taranis X9D, and I feel pretty much the same. I was very curious as to your opinion. I agree, once you get over the learning curve and really see what it can do, it's pretty amazing. I too, have only scratched the surface.

It is sad that you haven't been able to fly much in the last two years. @FDS turned me onto these receivers for FrSky:

https://hobbyking.com/en_us/catalogsearch/result/?q=frsky v6r4

15 bucks and great for all those four channel planes. I hope you get to fly more, soon!