Jump takeoff ~ The real deal ???

[Rotor Rooter]

Seriously ~ Has anyone ever considered using the supports as the means of providing jump takeoffs (and landings)?

[Victor Duarte]

Dave,
you call one of your designs "nemesis" , i suppose someone of your intelligence knows what nemesis mean... do you think people deserve to be punished or are you gone kinda kinky ? :whip: :twitch:
what about the whipercopter ?

[bones]

ok one small question, what would happen to the rotors in the type of take off?, remembering they need to be in +G's other wise strange things happen.

[DennisFetters]

If the powers in the jump-legs, and equal power is not in the rotor system, it's just coming down after the jump. So might as well use the rotor system for the jump, since you got all that power stored up anyways, and save all the weight and complicity of a jump-leg system, aye?

[Heron]

Fleas have a better system, capable of 9 G´s . . .
Heron

[Rotor Rooter]

Victor,

The 'Nemesis' was originally called the 'Igornemesis'. However, that was getting a little tooooo personal.
are you gone kinda kinky Yes, I'm tri-sexual. The initial post is just another attempt at trying to 'get it up'. http://www.unicopter.com/ThumbsUp.gif


bones,

That is one big question.

I never thought about applying the idea to a gyrocraft that only had a basic teetering rotorhead. Part of the thinking had to do with making a STOL fixed-wing into a VTOL fixed-wing. It had to do with Quadrirotor's earlier thread and the mention of an airplane that could jump up off the wheel chocks.

Then again, perhaps there was just very little thinking.


Dennis,

There is no argument with what you are saying. It is just that I (out of ignorance) have concerns about the ability to generate sufficient inertia in a rotor, and then safely lift a craft off the ground and transition at GW.

One of the gyro manufacturers is developing landing gear that can accept a large force upon landing. It would seem that this landing gear could be significantly enhanced so that it would also compliment existing jump-takeoff devices.

A possible idea would be to use a type of light-weight air cylinder. Plus a small compressor on the engine to created the necessary air pressure while the engine is warming up.

The objective would be to utilize the stored energy from the rotor, the legs, and of course the gas tank (via the motor and propeller) at the time of take-off.

Just a wild idea.


Dave

[Victor Duarte]

Dave,
peaceful gyro meetings would look like somthing like this :
http://youtube.com/watch?v=u-_i8VGwsNc
notice the blue label on the ground that indicates that this car and his driver are at their right place.

[DennisFetters]

Dennis,There is no argument with what you are saying. It is just that I (out of ignorance) have concerns about the ability to generate sufficient inertia in a rotor, and then safely lift a craft off the ground and transition at GW.

Well, there is no problem spinning the rotors up to jump speed, I've done so in two designs. The big deal is you need to de-pitch the blades, and you need a blade design that does not produce lift and drag at flat pitch, like all the gyro blades now used do. The trick is to ratio the power RPM of spin-up to the output torque of the engine RPM where you don't need a variable pitch propeller. There you have it.


One of the gyro manufacturers is developing landing gear that can accept a large force upon landing. It would seem that this landing gear could be significantly enhanced so that it would also compliment existing jump-takeoff devices.
A possible idea would be to use a type of light-weight air cylinder. Plus a small compressor on the engine to created the necessary air pressure while the engine is warming up.

The need for heavy shock absorption landing systems went out with the old autogyros, but hey, it would look neat!

The objective would be to utilize the stored energy from the rotor, the legs, and of course the gas tank (via the motor and propeller) at the time of take-off.

Anythings possible, even if not practical. Be nice to see it work.

Just a wild idea. Dave

Absolutely nothing wrong with that, in fact it's encouraged!

Dave[/QUOTE]

[Victor Duarte]

tip jets
tip jets
tip jets

[MikeBoyette]

http://youtube.com/watch?v=3RPYWmdv174 or this
http://youtube.com/watch?v=nWjBTROfLMQ

[DennisFetters]

tip jets
tip jets
tip jets

That is an answer, and it has been done. If you want to see just one of the problems you need to overcome, just go to your gyro, grab the rotorblade by the tip, stick an air hose nozzle at the drain hole and give it a shot! If they don't blow apart, whey will swell up to where you will be afraid to ever fly them again.

As I said, it's been done, but there are lots of things to be considered and redesigned. Nothings easy, I've always said.

[Victor Duarte]

Dennis,
yes, i still thinking there are a lot of things to be done and re-thinked.

for example : tip jets are very noisy because the nozzles were usually at the tip or near that made blade tips noisy because each blade tip encouters the high pressure air, sound wave of the other blade, thus producing more noise.

a thing that should be tried is : a larger nozzle at, let's say 8/10 th of the blade span, blowing the air a little UNDER the blade. that way the other blade won't encouter so much air pressure but will take profit or the pressure released in the downwash, producing, IMO, a little additional lift with less noise.
maybe someone should try it.

[Rotor Rooter]

Victor,

Re support enhanced jump take-offs;
"Peaceful" ultralight "gyro meetings would look like something like this."
http://youtube.com/watch?v=VsaAgOp0pZI


Dennis,

Yes, the small amount of twist in a gyro blade, when compared to a helicopter blade, must significantly reduce the induced drag at zero thrust.

Are you hinting at the use of a partially powered rotor as a means of slowing down the loss of rotational inertia after take-off? :)


My philosophy is that of throwing enough crazy ideas at the wall in the hope that occasionally one will stick. For now this idea gets files in the Department of Demented Designs.

Dave

[DennisFetters]

Dennis,
yes, i still thinking there are a lot of things to be done and re-thinked.
for example : tip jets are very noisy because the nozzles were usually at the tip or near that made blade tips noisy because each blade tip encouters the high pressure air, sound wave of the other blade, thus producing more noise.
a thing that should be tried is : a larger nozzle at, let's say 8/10 th of the blade span, blowing the air a little UNDER the blade. that way the other blade won't encouter so much air pressure but will take profit or the pressure released in the downwash, producing, IMO, a little additional lift with less noise.
maybe someone should try it.

Definitely worth a try!

[DennisFetters]

Victor,

Re support enhanced jump take-offs;
"Peaceful" ultralight "gyro meetings would look like something like this."
http://youtube.com/watch?v=VsaAgOp0pZI

Dennis,
Yes, the small amount of twist in a gyro blade, when compared to a helicopter blade, must significantly reduce the induced drag at zero thrust.

Sorry, I guess I didn't make myself clear. I'm not talking about twist, nor did I use twisted blades. I was talking about the airfoil shape. All (mostly all) simi-symmetrical airfoils make lift, and drag at a flat pitch, meaning much more power is necessary to spin them up. You need a special airfoil, or a fully symmetrical for the job.

Are you hinting at the use of a partially powered rotor as a means of slowing down the loss of rotational inertia after take-off? :)

Bensen did that with his "Power-Rotor" system, which was a small motor hooked to the head, which put 2 or 3 hp into the blades in flight. Worked, but you had to have that little motor running all the time.

No, do a jump take off and that's it. It would be a much more complicated system if you were to try and add a little power, and not to much power. Something else for the pilot to screw up.

My philosophy is that of throwing enough crazy ideas at the wall in the hope that occasionally one will stick. For now this idea gets files in the Department of Demented Designs.
Dave

Dave, I agree, but it's not the ones that "stick" that worry me. It's the ones that "BOUNCE BACK" that hurt.

[birdy]

Fleas have a better system, capable of 9 G´s . .
bloodyell, 9 g's!!!!!!
Well, youd get a good look at your asshole everytime you took off, if thats wot takes your fancy,

[Passin' Thru]

>snip < I'm not talking about twist, nor did I use twisted blades. I was talking about the airfoil shape. All (mostly all) simi-symmetrical airfoils make lift, and drag at a flat pitch, meaning much more power is necessary to spin them up. You need a special airfoil, or a fully symmetrical for the job.

That is not correct, but it is a very common misconception. For asymmetric airfoils such as say the NACA 8-H-12, aerodynamic pitch is totally different from geometric pitch. Unless one understands this, the entire design will be completely erroneous. To eliminate or minimize induced drag, the blades pitch must be reduced to zero aerodynamic pitch to produce zero lift. In the case of the above mentioned NACA 8-H-12 airfoil, that equals approximately 4 degrees negative geometric pitch. The two JTO hubs I built to use the old style Rotordyne blades, the zero aerodynamic pitch was about 2 ½ degrees negative geometric pitch and they worked reasonably well. I don’t recall what the profile designation was, but they were basically flat bottomed with a smaller LE radius than their later ones, and LE radius was slightly higher with a bit of Phillips entry extending back to about the quarter cord balance point.

[DennisFetters]

That is not correct, but it is a very common misconception. For asymmetric airfoils such as say the NACA 8-H-12, aerodynamic pitch is totally different from geometric pitch. Unless one understands this, the entire design will be completely erroneous. To eliminate or minimize induced drag, the blades pitch must be reduced to zero aerodynamic pitch to produce zero lift. In the case of the above mentioned NACA 8-H-12 airfoil, that equals approximately 4 degrees negative geometric pitch. The two JTO hubs I built to use the old style Rotordyne blades, the zero aerodynamic pitch was about 2 ½ degrees negative geometric pitch and they worked reasonably well. I don’t recall what the profile designation was, but they were basically flat bottomed with a smaller LE radius than their later ones, and LE radius was slightly higher with a bit of Phillips entry extending back to about the quarter cord balance point.

Well, you are correct, that it needs to be reduced to a negative 4 degrees to not create lift. The problem is like I said, if it's flat it still produces drag because of the lift. If it's at negative 4, it's not producing lift, but it is producing the same amount of drag because of the negative pitch. I know, because that was my first attempt.

There is another airfoil I use that at flat pitch produces the least amount of drag.