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Help! Pugachev's Cobra

#1
Is this manover even posible on a small scale aircraft. and if it is how do you do it! (craft has thrust vectoring and stabilitors)

Uses aircrafts structure a air brake
 
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Vimana89

Well-known member
#2
Absolutely possible. There are some lower aspect planes and deltas that are good in high alpha without any fancy thrust vectoring or stabilizer systems. An FT Nutball, Flyer, and I'd imagine their delta, could all do it. Look at my Avatar. It's my own extra slender delta 3ch RET design. The rudder gives it fine control on high angles of attach(such as the "Cobra").
 
#3
Absolutely possible. There are some lower aspect planes and deltas that are good in high alpha without any fancy thrust vectoring or stabilizer systems. An FT Nutball, Flyer, and I'd imagine their delta, could all do it. Look at my Avatar. It's my own extra slender delta 3ch RET design. The rudder gives it fine control on high angles of attach(such as the "Cobra").
how hard is it to do, I am building an su-27t that is known for being able to preform this manover at a high rate of speed
 

Vimana89

Well-known member
#4
As far as I know, the Cobra is just a straight forward flare to a very high angle of attack. My design(and I'd imagine the Nutball and Flyer) can do more, and even turn and maneuver around somewhat while maintaining the "cobra".


At about the 1:10 minute mark, I start doing all the cobras and high alpha stuff.
 
#5
As far as I know, the Cobra is just a straight forward flare to a very high angle of attack. My design(and I'd imagine the Nutball and Flyer) can do more, and even turn and maneuver around somewhat while maintaining the "cobra".


At about the 1:10 minute mark, I start doing all the cobras and high alpha stuff.
thanks for the help
 

Vimana89

Well-known member
#6
how hard is it to do, I am building an su-27t or su33 that is known for being able to preform this manover at a high rate of speed
Those should work, but I'm not sure it will come as natural with a tailed fighter. Tailless deltas and other low aspect shapes like the Nutball do it easier, but it is definitely possible with the planes you want to use, even in scale. You will want to have a little bit of excess thrust and a low weight, whatever type of plane you will use. To get excess thrust, make sure you got a good power plant that provides a good thrust to weight ratio, calculate your wing loading, and use a three or four blade prop, which will be a little less energy efficient, but provide the spare thrust you need especially at low speed and throttle.
 

Vimana89

Well-known member
#8
They do look very similar and the wing is about identical, but the canards ion the SU-33 would probably make it a bit better choice out of the two for what you want to do with it. The canards add some pitch stability, which makes stuff like the Cobra easier and smoother.
 

Vimana89

Well-known member
#9
Basically, in summary: If you are chosing between the SU-27 and SU-33, either should work, but the 33 might have a slight advantage for the Cobra and high alpha stuff. Make sure you check your wing loading and make sure your thrust-to weight ratio is good. If using a prop build rather than EDF, use some three or four bladed props to get the spare thrust at low speed to do those maneuvers. If you do all this and also get the basics right(thrust andgle, center of gravity, ETC.), there's no reason you can't do the Cobra.
 
#10
They do look very similar and the wing is about identical, but the canards ion the SU-33 would probably make it a bit better choice out of the two for what you want to do with it. The canards add some pitch stability, which makes stuff like the Cobra easier and smoother.
the su-33 is an su-27t but it has a different designation
 

Vimana89

Well-known member
#11
the su-33 is an su-27t but it has a different designation
That makes sense. Wasn't as familiar with the full scale history on that one. What I said remains though, the main difference is the canards on the 33, which help with pitch stability in high angles of attack. If you go with the SU-27T version with no canards, it should still do the Cobra, but you might need to work a little harder/won't be quite as smooth to maintain pitch stability in high alpha.
 

Vimana89

Well-known member
#13
ok do you thank thrust vectoring can help with stability
If you have the time, resources, and skills to add thrust vectoring to your builds, it will absolutely help with stability and high alpha aerobatics such as the Cobra. If you are more of a novice or beginner builder and pilot, I'd try something easier first without thrust vectoring.
 
#14
If you have the time, resources, and skills to add thrust vectoring to your builds, it will absolutely help with stability and high alpha aerobatics such as the Cobra. If you are more of a novice or beginner builder and pilot, I'd try something easier first without thrust vectoring.
I'm actully going to put in a gyro and stability surfaces controled by the gyro to make it alot easier to fly
 

cranialrectosis

Faster than a speeding faceplant!
Mentor
#16
Two things... Usually when one of my planes acts like the one in the gif, I go pick up the bits and put them in a bag... Not saying that will be your end result, but if you are new to flying, be prepared. Carry a large plastic yard bag for bits.

im filling this plane with all the tech so it will last a long time. at least thats the hope still prototyping
All planes have a shelf life. One reason we use foam board is that it is cheap and easy to repair/replace. The cost of parts and the cost in time to build with foam is pretty low. The point being that if you fly you WILL crash. I strongly recommend you start simple and cheap with the understanding that if your first plane survives its maiden voyage, you are incredibly lucky.

Of course if building these is old hat to you and you have years of piloting experience, I am probably dipping without chips.

If you are new to the hobby, I STRONGLY recommend you question the 'last a long time' concept and instead focus on building planes you can learn on. Planes that you won't mind crashing and picking up with a bag and laughing at with friends at the end of the day.

IMO that is a much better (and cheaper) way to learn.

Welcome to FliteTest @Noodles .
 

Vimana89

Well-known member
#17
Two things... Usually when one of my planes acts like the one in the gif, I go pick up the bits and put them in a bag... Not saying that will be your end result, but if you are new to flying, be prepared. Carry a large plastic yard bag for bits.



All planes have a shelf life. One reason we use foam board is that it is cheap and easy to repair/replace. The cost of parts and the cost in time to build with foam is pretty low. The point being that if you fly you WILL crash. I strongly recommend you start simple and cheap with the understanding that if your first plane survives its maiden voyage, you are incredibly lucky.

Of course if building these is old hat to you and you have years of piloting experience, I am probably dipping without chips.

If you are new to the hobby, I STRONGLY recommend you question the 'last a long time' concept and instead focus on building planes you can learn on. Planes that you won't mind crashing and picking up with a bag and laughing at with friends at the end of the day.

IMO that is a much better (and cheaper) way to learn.

Welcome to FliteTest @Noodles .
I was going to say something like this, good call(y). If you are new, use a simulator and build and fly some simpler planes. I'd get/make like a standard basic trainer, plus a couple basic 3ch planes that can do all the Cobra/high alpha stuff you want to do. After that, build a basic prop in slot version of your SU-27 or SU-33, with a three or four blade prop and excess thrust like I stated earlier, and translate the high alpha skills you learned on more basic planes to that. After that point you could start looking into thrust vectoring and whatnot. You don't want to depend on the idea of foam air frames lasting indefinitely, especially if you are new.

If you need help picking an easy high alpha plane, there are three that come to my mind as quick and easy to build and very capable of what you want to do with them and more; the FT Nutball, FT Flyer, and my own V Sliver slender delta. There are plans available for all three, and the Nutball and Flyer come in a three pack speed build kit with a delta that's a little harder to fly, but still very nice.
 
#18
I am traning on a ft spitfire w/ 25% rates and have very deep understanding of flight and aircraft design. I am building it to help train with a faster aircraft, and learn some aerobatic manovers later in the futer. This plane is in the works i've only completed the nose and one wing witch i Have to remake due to some cat issues. Aswell hoping i can perfect it and release plans so others can learn off of it aswell. The tech is for stabillity and trying new things that hopfully give it a long shelf life. I chose this aircraft becase poeple can tune and change charactistics of the craft. Thanks For the Help!!!
 

Vimana89

Well-known member
#20
I am traning on a ft spitfire w/ 25% rates and have very deep understanding of flight and aircraft design. I am building it to help train with a faster aircraft, and learn some aerobatic manovers later in the futer. This plane is in the works i've only completed the nose and one wing witch i Have to remake due to some cat issues. Aswell hoping i can perfect it and release plans so others can learn off of it aswell. The tech is for stabillity and trying new things that hopfully give it a long shelf life. I chose this aircraft becase poeple can tune and change charactistics of the craft. Thanks For the Help!!!
Nice(y). That's a fairly good place to start looking at a project like this.It helps knowing your experience level. You may want to ask around, and see what sort of thrust vectoring setups are available, you will have choices between various prop in slot and straight pusher setups, as well as ducted fans. If you need advice on thrust vectoring setups or setting up things like gyro stability, I'm not the one to answer that.

I'm still somewhat a novice, and haven't worked with those things myself yet, but I know enough about flight as it applies to RC scale to know that none of that fancy stuff is a requirement to do the Cobra and all sorts of high alpha. Those moves can be done on what's basically a circular(or trapezoidal or triangular) sheet of foam with dihedrals and a prop, rudder, and elevator(or other 3ch setups such as AET or elevons), with nothing else involved but whatever basic 3ch control surfaces you've got and throttle. A plane with all the bells and whistles you are adding should have no trouble, so if you can build and fly at a level to use those at all, your plane should be great.