Cormorant II

[Pieliker96]

Introducing the Cormorant II
A Twin-Engine Transport Plane with Fowler Flaps and Drooperons

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What is this thing?
The Cormorant II started as an aircraft in Kerbal Space Program, a rocket/plane/rocket-plane simulator game that got me into aerospace. The goal of the craft was to be an aerobatic cargo plane with decent STOL capability. I accomplished this by the Kerbal mantra of "More Boosters" (engine spam), as well as adding massive flaps and leading-edge roll control surfaces. In 2019, I stole its name for a RC plane of a similar goal, of which I was never really happy with the performance - The thrust to weight ratio was lower than I wanted, and roll authority and stability were both lacking. I was planning on scrapping that airframe for a new design, and decided to try and replicate the craft from KSP, which this is the result of. It's got a high wing for roll stability, big externally blown offset-hinge fowler flaps for slow flight, more powerful motors for more thrust, and drooperons to increase roll authority as inspired by the original KSP aircraft and this video of Ben Harber & his Zupair Zulu. Changing the name felt wrong, as this new airframe was more true to the original; I settled on "Cormorant II".

Electronics & Configuration
It runs on Twin Power Pack F (2x RS2205 on 6x3/4.5 or 5x4.5x3 props) and a 2250 3s. All-up-mass is 900g, which gives it a thrust-to-weight of 1.5 with the 6x4.5 props. It has a 51.6" span and a wing cube loading of 6.9. It uses 4 or 6 9g servos, depending on if the builder chooses to forego the flaps. The flaps can be configured as split or fowler, with the latter using craft sticks for the offset hinge. The optional drooperons enhance roll rate for the more aerobatically-oriented pilots.

Building Details
This plane is intended for someone who has prior experience with Flitetest plans and planes - it is not a good first or second build. The wing is a traditional FT style wing, and the fuselage is closer to the FT Master style of construction: Is uses formers and skin to form a semimonocoque shell, as opposed to the simple box style with A and B folds and the like.

Plans
Cormorant II Plans (v1.2)

Build Video

Flight Video

 

[stereodreieck86]

I know one thing for sure, you are crazy.

 

[Tench745]

I'll be watching this one.

 

[Pieliker96]

I got the first development vehicle completed today, and found 20 things that I'll need to change for the final release. I'll use this as a glide test vehicle to find a good CG location. I'm also considering scaling the final plans down a tad to give it a bit more pep in the air.
The only foam I was able to get was a bit thinner than the usual DTFB stuff, which meant my formers were effectively undersized - the seams shown here are not optimal in the slightest, I think I can achieve a much smoother final product.

 

[b-29er]

Nice looking design! Looks modern and sleek, kind of like Peter's V2 guinea before that vanished into thin air. The straight back is also really nice, since i'm betting that makes construction a breeze. I'm very curious about rudder authority, especially given the size of the rudder and the amount of airflow that may get blocked at lower airspeeds with those flaps. Are you thinking of having stabilization on the aircraft or rudder-controlled throttles? Also, what about scaling up to a B or C powerpack for more pep and cargo capabilities?

 

[Pieliker96]

Nice looking design! Looks modern and sleek, kind of like Peter's V2 guinea before that vanished into thin air. The straight back is also really nice, since i'm betting that makes construction a breeze. I'm very curious about rudder authority, especially given the size of the rudder and the amount of airflow that may get blocked at lower airspeeds with those flaps. Are you thinking of having stabilization on the aircraft or rudder-controlled throttles? Also, what about scaling up to a B or C powerpack for more pep and cargo capabilities?

I've run the numbers on the vstab/rudder area, It's around the tail volume coefficient of a single-engine plane. Considering I'll be using counter-rotating props, I think that's appropriate - although it probably won't have much engine out capability if much at all - not that it needs it anyways. I'll be using toggleable differential thrust for aerobatic purposes.

I'm really curious to see how this design performs at high alpha, especially with the flaps deployed. With a high angle of attack, the tail is effectively below the wing, which I'm hoping will keep it out of any major turbulence or blanking effects. This is something that will have to be evaluated when I go and fly it.

This design actually started off as designed for twin C pack before I scaled it down to fit electronics I already own. I've certainly toyed with the idea of a "Super Cormorant" with a slightly larger wingspan (5-6 feet) using twin C pack, as it feels a bit wrong to fly a plane with a wingspan of over 4 feet with a pair of quad motors and 6 inch props. I've run the numbers, and it theoretically should have a similar thrust-to-weight ratio and a slightly lower wing cube loading than planes oriented towards the same flight envelope (FT Big & Mini Guinea, Bushwacker). For those who want that extra bit of oomph on the current small design there is always the option of using 30A ESCs and going to 4 cell, which would really make it scream.

 

[Pieliker96]

The beta plans have been released. They represent the initial plans plus corrections from the experience of building the first test vehicle, and come without a build guide. If you'd like to have a go with these, I'll help you along the way - although you could wait a month for the final plans and build video.

 

[AIRFORGE]

Nice work, @Pieliker96 ! Looking forward to more of this one!

 

[L Edge]

Did you fly it yet?

 

[Pieliker96]

Did you fly it yet?

No, as I haven't built the final version with electronics yet. I'm at college currently, the electronics and tools I need to do so are over a thousand miles away . ETA for the first flight-worthy prototype is within two weeks, with the build video coming late December.

 

[jfaleo1]

The beta plans have been released. They represent the initial plans plus corrections from the experience of building the first test vehicle, and come without a build guide. If you'd like to have a go with these, I'll help you along the way - although you could wait a month for the final plans and build video.

Well maybe I will. 😁 This design is very interesting, and since I barely get to fly, and I recently decided to tear down my quinjet, I have some parts to transfer to a larger build. Man though, this is screaming for EDFs so I may have some fun here. Or maybe 2 wings one EDF one with props. If I do start work on it I may have some questions on the flaps, drooperons and nacelles.

I do wish you and @Grifflyer were not so great at making us old folks look like such hacks.
But I’ve always been a better pilot than builder and design engineer in the RC world.

 

[Pieliker96]

And we have flaps!



My solution to fowler flaps was an offset hinge using popsicle sticks and pushrod wire. It's surprisingly sturdy in the necessary directions, it'll be interesting to see how it performs in flight. If all goes well, I should have the wing done by tonight and the fuselage by afternoon tomorrow.

 

[Monte.C]

View attachment 183852

I got the first development vehicle completed today, and found 20 things that I'll need to change for the final release. I'll use this as a glide test vehicle to find a good CG location. I'm also considering scaling the final plans down a tad to give it a bit more pep in the air.
The only foam I was able to get was a bit thinner than the usual DTFB stuff, which meant my formers were effectively undersized - the seams shown here are not optimal in the slightest, I think I can achieve a much smoother final product.

But that's a good looking piece of work you got there. Looking forward to the next version.

 

[Pieliker96]

https://imgur.com/YMV46l0

The wing is complete. The ailerons, drooperons, flaps, and both motors (including differential thrust) are functional. Next is the fuselage, nose, and tail. I must say, it takes quite a lot longer to get things done when you have to film everything! I chose to use one ESC's BEC to run the wing, the other will run the RX and the tail servos. It just seems a tad much to put six 9g servos on a 3A BEC.

 

[Monte.C]

View attachment 186268

https://imgur.com/YMV46l0

The wing is complete. The ailerons, drooperons, flaps, and both motors (including differential thrust) are functional. Next is the fuselage, nose, and tail. I must say, it takes quite a lot longer to get things done when you have to film everything! I chose to use one ESC's BEC to run the wing, the other will run the RX and the tail servos. It just seems a tad much to put six 9g servos on a 3A BEC.

That is insane!

 

[Monte.C]

And the internet is such an amazing thing. Used to be the only way one could connect with amazing builds and builders like this is by reading an article in an RC magazine. Now we're like one big community, communicating and sharing information instantaneously with the cream of the crop of designers & builders.

A long time ago I told myself "Keep your eyes open or you'll miss it... There are going to be such amazing things happen in the world in this lifetime. Unbelievable things, but you might hardly notice." Now we have real personal jetpacks. Now we have one-wheeled motorcycles. Haha!

(Sounds like Ferris Bueller.)

Nice work @Pieliker96!

 

[L Edge]

A suggestion for your fowler flaps. Why don't you slow the servo speed down say one to 2 secs in your transmitter. That way, it gives you a chance to reverse direction if needed. Like your design for the ff.

Very interested in your drooperons with that wing rotation. Should be very interesting in the turns. Did an investigation of the just the wing inclined at various angles. Watch for possible stalls.

 

[Pieliker96]

A suggestion for your fowler flaps. Why don't you slow the servo speed down say one to 2 secs in your transmitter. That way, it gives you a chance to reverse direction if needed. Like your design for the ff.

I would if I could, but my TX (Graupner MZ-12) doesn't support it. The B-1B's mechanism relied on a linear actuator that required ~8 seconds to travel from one extent limit from another regardless of the PWM signal's slew rate.
I agree that the drooperons are one of the big unknowns with this project.
The plane is pretty much done at this point, I'll have an update in a couple of hours, possibly with a controls check and/or taxi test.

 

[Pieliker96]

Ready for Flight!

 

[Monte.C]

View attachment 186353

View attachment 186354

Ready for Flight!

Killer. Show us the belly!