RAF Flight Behaviour

[PTKay]

Another good one, this time experimental:

http://www.aero.hut.fi/pubs/reports/AAL ... io-2_1.pdf

It refers to M16, but the conclusions are general:

Table 3 shows that the VPM M16 autogyro is not stable if there is no horizontal tail.
Without a horizontal tail there would be an unstable short period motion,
a stable phugoid motion and a stable aperiodic motion at the airspeed of 63mph.

[saraf]

Ptkay, do you have any magni hours? Have you flown a magni without a HS?

If not, please make use of MAK earlier suggestions...

[Learjet]

I have a fair bunch of Magni hours, but I think I'll take the advice of the Emeritus Professor of Aeronautics study paper and not try to fly a Magni without a horizontal stab.

[saraf]

Hi Dave

Bring yours to me i have a fair amount of hours in gyros without HS. I will give it a go..............

[Learjet]

Hi Dave

Bring yours to me i have a fair amount of hours in gyros without HS. I will give it a go..............

Eben, and you know that I have no doubt that you have the skill and experience to fly it 100%!

What's interesting is your comment has made me realize that this almost mirrors the RAF scenario - with the right training and experience I have no doubt that a Magni could be flown without the horizontal stab despite its alleged inherent instability without it. I guess fitting the large stab onto the Magni has probably dampened its handling performance somewhat too, but its also probably a small price to pay for the resultant safety and stability which has played a large role in its sales success around the world. Maybe there's a lesson to be learned there that compromising handling performance for increased stability is a sacrifice customers are happy to make...

[PTKay]

Ptkay, do you have any magni hours? Have you flown a magni without a HS?

If not, please make use of MAK earlier suggestions...

I really don't know, what is your problem.

I am just quoting the results of the research done by one of the most renowned
aeronautic institutes. They just say, HS is a necessary part of the stability characteritics.

The rules in Europe are clear. There are even formulae to calculate the size
of the HS in a gyroplane. The German BUT just clearly requires them.

http://www.rotaryforum.com/forum/showthread.php?t=36180

[PTKay]

Hi Dave

Bring yours to me i have a fair amount of hours in gyros without HS. I will give it a go..............

Eben, and you know that I have no doubt that you have the skill and experience to fly it 100%!

There are certainly many people out there, who can ride a monocycle.
With enough training probably everybody can be made able to ride it.

For some reason most people ride bicycles, not monocycles, and sales
of bicycles are far exceeding the sales of monocycles.

For some reason, the cars have four wheels, although a 3-wheeler is a doable solution.
Probably the 4-wheelers are just more stable, and most people prefer them over 3-wheelers.

At the moment there are probably few thousands of gyroplanes with HS flying around the world,
(alone AutoGyro GmbH sold 1000 MTO) and maybe something around hundred without.

It is your call, and your business decision.

[Vertical Tango]

I don't understand why so many people "demand" that the RAF be like what they currently fly. I keep on coming back to the R22 analogy, why don't we "demand" that the R22 have a HS ? The RAF does well in its category, if we don't like flying without a HS then we must not fly nor buy a RAF. It is their marketing decision and an individual choice. I think that some have a problem with the fact the RAF is not part of the "groupy" and doing well as such. It is simply a different machine and we should accept it, regardless what what the Brits, Germans etc say. If the local SACAA has accepted that the machine can be sold here and is technically sound, it is now RAF SA prerogative to decide on their marketing strategy if they want to improve their sales. They seem to be very happy the way it is and we should stop bashing them. We are "pretending" saving the nation and avoiding disasters. Please Everyone is adult enough to make up his own decision.

[Learjet]

Absolutely agree with you Vertical Tango I for one would love to see more RAFs flying in South Africa. But I'm also a (marketing) pragmatist and whilst Henry Ford may have felt that there was no reason for a Model-T to be produced in any colour other than black, the same could not be said for his customer's preferences. It is a fact of modern day consumerism. The current market demand (rightly or wrongly) is for inherently stable, easier to fly gyros. The broader market perception (true or false) is that a horizontal stab is a requirement thereto. In marketing, perception is reality, and as PTKay correctly states - ultimately it is a business decision. I have long felt (and previously expressed) that RAF should offer the option of a h stab, if only to meet customer expectation and demand. I'm not an aeronautical engineer and unqualified to offer any opinion on the aerodynamic necessity thereof, but I believe from a marketing perspective the option of a HS would contribute positively to RAF gyro sales and stop a lot of the anti-RAF sentiment "noise" out there.

[saraf]

Hi dave,
Me and you have spoken about this for a couple of years and you know my point of view.......
But maybe the white jacket folk can explain the following statement to us?

Based on stability analysis they have reached the conclu- sion that for the stability the position of the centre of mass with dc to the propeller thrust line is the most important factor

and further, that the horizontal tail of the VPM M16 has a very limited effect on the longitudinal dynamics. “Even at the high speed end of the range the aerodynamic properties of the vehicle pod and tailplane have little influence”

Or maybe my english understanding is just not up to scratch

May you all have a great Fathers day and may the wife's and kids spoil you all......

Maybe i will to treat the kids take them for a flip in RAF......

[Gyronaut]

vance breese
Join Date: Oct 2003
Location: Nipomo,California
Posts: 9,039

In my opinion too much horizontal stabilizer is better than too little.

How about that game of darts then? 3 darts against me without Horisontal Stablisers, my 3 darts with HS's. I am not a good darts player but I favour my odds with the HS.

So sue me.

[mikemat]

Holy crap! It seems the more things change, the more they stay the same. Having honourably (I think ) discharged my self from the gyro flying fraternity some 3 years ago, I paid a visit to the site only to find that the HS debate rages on. In fact, I could swear that the input of some was a 'cut and paste' from previous versions of the same

I thought that I had successfully put the debate to bed in 2009 when I attached a pic of the H Stab I had affixed to my RAF and opined that, in my view, it severely hampered the flight characteristics of my untamed beast. For those who did not follow the fourteenth (I think) thread on the subject, I have taken the liberty of reattaching the pic. RAF's and H Stabs are like oil and water, they just don't mix, so please leave all my stabless RAF mates alone and pick on someone else.

[Gyronaut]

[John Boucher]

PTKay... please carry on providing info - irrelevant if you fly or not or don't have hours in whatever.... I do however caution posters to not let this discussion degenerate into a "play the man and not the ball" thread. If you want throw some sarcastic remarks, use the PM system as provided.

There is so much knowledge out there. If you don't agree with the technical statements just say so and prove otherwise but without the finger wagging stuff please.

[mikemat]

A few definitions:
= take what i said with a pinch of salt (does not = sarcastic)
= joking (does not = sarcastic)
= seriously joking
Lighten up - eish!