2 stroke thread (with occasional F1 relevance!)

[J.A.W.]

I am still waiting for one justified "objection", from anybody.

If you have a lot of free waiting time you could take some of the photos and measurements I suggested in my post. That way we could do a bit of non photographic modeling.

Or, nzjrs, instead of yet another post relentlessly providing opinion-based gainsaying,
perhaps you could build a flying (Reynolds number compensated) scale model, to prove your point?

[nzjrs]

I am still waiting for one justified "objection", from anybody.

If you have a lot of free waiting time you could take some of the photos and measurements I suggested in my post. That way we could do a bit of non photographic modeling.

Or, nzjrs, instead of yet another post relentlessly providing opinion-based gainsaying,
perhaps you could build a flying (Reynolds number compensated) scale model, to prove your point?

Indeed, I did suggest scale model building too, as a means to verify some of manolis opinions.

(maybe you were confusing me for someone else? I've offered to do some modeling if provided with the necessary data)

[Rodak]

Can an English speaking member of this forum translate to Rodak my last post?

Nice.

For your 'explanations' of control inputs the pilot must be free to move his body. In a previous post (some time ago) you said the harness would extend to the waist and rigidly fix the pilot's upper body. Is that no longer the case? In your illustrations about dive recovery you show the pilot's body bending in all directions, and the motor unit seems to be sitting on the shoulders. How, exactly, is this unit attached to the pilot? Specifically, where are belts, etc located and how is the, according to you, up to 2 g load transferred to the pilot's body? Is he sitting in some sort of parachute harness, or do you plan to just put loops through the pilot's armpits? Once you reveal your mounting system we will be able to see how much movement the pilot has and whether there is controllability from c.g. shift. As for your pretty girl picture, I suggest you hang by your armpits and curl your legs up like that; if you can even do it I doubt you can sustain the position for more than15 seconds. Now blow 100 mph air past you and do it again......

[manolis]

Hello Rodak.

What you ask was answered a year ago by the following drawing (Page 180, November 2019):



According the drawing, the gray parts (at right top) are fixed with each other (torso / back / Portable Flyer), while the beige parts (at right bottom) are hinged on the torso/back (and so they are free to move relative to the "torso / back / Portable Flyer" assembly).

The only requirement is the Portable Flyer to be secured to the torso / back of the pilot (it does not matter the specific way: with ropes? with a "saddle? with a jacket? with the harness used by Yves Rossy? with glue? choose your favorite way), leaving the hip / legs / arms / neck / head free to move.

Thanks
Manolis Pattakos

[Rodak]

Manolis, I am asking exactly this: how is the motor unit attached to the pilot? With the pilot, according to you, subject to 2 g loads pulling him from the motor during deceleration, the way he is attached is critical. I think you need some sort of parachute harness/seat that goes through the pilots crotch area. As I mentioned previously, I climb and am familiar with hanging loads; a rope around the waist will not work. What you show is great for carrying the weight of the power unit on one's shoulders, but when the load direction is reversed, which it will be during flight, I see huge problems both with support and comfort. Please clarify. And don't tell me it's up to me, this is your design and this is a critical element for a number of reasons.

And thanks for that NathanE. Round and round we go, where we stop nobody knows.....

[manolis]

Hello Rodak

You write:
"And don't tell me it's up to me, this is your design and this is a critical element for a number of reasons."


Take the case the Portable Flyer is secured to the pilot by the harness of Rossy's DeltaWing jetpack:



Thanks
Manolis Pattakos

[Rodak]

Okay, well, how exactly are you going to attach the pilot to the power unit? Rossy obviously has a parachute type harness with crotch straps across the thighs which would definitely limit waist and leg movement . His thighs are strapped to the other attachments which would limit any type of 'lift your legs' motion described in your recovery from a vertical dive. What gives? (This means, in English, 'please explain')

[manolis]

Hello Rodak.

You write:
"His (Rossy's) thighs are strapped to the other attachments, which would limit any type of 'lift your legs' motion described in your recovery from a vertical dive. What gives?"


The recovery from a vertical dive can be done with or without the legs (say, with the legs straight / frozen).

What is required for the recovery from a vertical dive is just a part of the body (say the head? say a hand? say an arm?) to move relative to the rest "assembly" displacing the overall center of gravity away from the thrust axis.

For instance, the astronaut can recover from a vertical dive (nose down flight) using only his neck / head, with all the rest body "frozen".

• quote from page 188:
  As he (Roosy) says, when he wants to go to a destination, he just turns his head towards the destination.

Try to get it.
This is the most important element in understanding the control of the Portable Flyer.



Having said that, let's get back to Rossy's harness.

Does the harness of Rossy restrict the motion (the mobility) of his legs?

The following video says no.

• See from 5:57 to 6:02; the harness is completely loose around Rossy’s thighs.
  
  See from 6:06 to 6:09; Rossy is sitting (with the DeltaWing secured on his back / torso, ready to fly) with his legs at an angle of about 90 degrees from his spine.
  
  See from 10:17 to 10:26; they walk making big steps to enter into the airplane.

During the high speed flight Rossy has to make effort to bend his legs, not because of the harness, but because of the aerodynamic forces. When he leaves free his legs, the are supported by an air mattress.

Thanks
Manolis Pattakos

[Rodak]

Okay, for the nth time, how is your pilot attached to the power unit? Straps under his arms, glue on his back, ropes around his waist, bungee cords, staples, what? 'What', in English, means 'what', like how.

[coaster]

The pilot training manual for PF states;
"In order to control the machine, physical training must be practiced regularly. This normally involves standing face towards a cinder block wall and repeatedly thrusting the pilots forehead towards the cinder blocks"

Can it be any clearer?

[NathanE]

The pilot training manual for PF states;
"In order to control the machine, physical training must be practiced regularly. This normally involves standing face towards a cinder block wall and repeatedly thrusting the pilots forehead towards the cinder blocks"

Can it be any clearer?

Sorry this is incorrect. I think what you meant to say was:

"In order to control the machine, physical training must be practiced regularly. This normally involves being suspended by the armpits face towards a granite block wall with hips articulated so as to hold the legs at a 30 degree angle away from the wall and repeatedly thrusting the pilots forehead to make forceful contact with the wall"

[Rodak]

See from 6:06 to 6:09; Rossy is sitting (with the DeltaWing secured on his back / torso, ready to fly) with his legs at an angle of about 90 degrees from his spine.

Sitting is NOT the same as hanging...... Please try hanging from a bar and getting your legs to 90° from your torso. So does your flyer use the same system as Rossy, a modified parachute harness type thingy? It's still unclear.

Time for my physical training...... My head hurts.

[manolis]

Hello all.

Yesterday it was received this Search Report:



from the UK Patent Office for the PatVRA invention:





(more at https://www.pattakon.com/pattakonVRA.htm )


Only two “A” documents were found (“A”: Document “indicating technological background and / or state of the art”).

Here are the two documents :

https://www.pattakon.com/VRA/DE102011075741A1.pdf

and

https://www.pattakon.com/VRA/WO2014174566A1.pdf

The first is in German language, the second is in Japanese language (abstract in English).
The drawings are in the “International Language”.


The first document has the same “priority document” with the following US patent:

https://www.pattakon.com/VRA/US8701616.pdf

which is in English (granted recently: 2014).


It is interesting that both inventions mentioned in the Search Report use balance webs to take some vibrations from the rotating crankshaft.


The PatVRA needs not balance webs; it is allowing the crankshaft to perform the irregular rotation it does (variable “instant” angular velocity of the crankshaft during a rotation), allowing at the same time the primary shaft of the transmission to rev at constant angular velocity.

In a straight-four even-firing four-stroke, the PatVRA permits only the combustion pulses to pass to the gearbox (and to the drive wheel(s)), making what the Yamaha R1 cross-plane crankshaft does without sacrificing the even-firing and without adding external balance shafts.



Hello J.A.W.

With the PatVRA, the three-cylinder flat-crank Laverda cound avoid some of their reliability problems, while the "feeling" of the rider would improve.


Thanks
Manolis Pattakos

[coaster]

I know how to prove PF (serious).
The propellors are the lifting point and effecting an angle will change course.
So, create a rig strapped to the body, hanging by rope mounted pivots at propellors mounting point.
Maybe a potentiometer to measure angles?
Swing around, establish the 'moves'.
I could not imagine more the 5 degrees total movement, perfect for fine control and gentle course correction, but, maybe not the scope for more agressive angles such as an emergency.

[henry]

You also write:
“You might even trunnion mount it In a suitable structure and verify some of your thoughts on controllability.”


The simplest way is, after the measurement of the “static” thrust (and the reliability tests) to secure a saddle (the brown part) on pilot’s back / torso, then secure the Portable Flyer on the saddle and make tethered tests

A trunnion mount would be a tethered test.

I suggest the trunnion attached to the saddle located at the CoG position. This would provide for movement in pitch but constrain other degrees of freedom. You could use this to verify your theories on transition from and to hover. A relatively small rig would allow testing of rider comfort and mobility, such as @Rodak is interested in. It would be relatively easy to Include full containment for the propellers etc, external to the flier itself.