Hip Pocket Builders' Forum

Outdoor Free Flight Forum => Power => Topic started by: RobinB on June 25, 2017, 05:43:54 PM

Title: Amen
Post by: RobinB on June 25, 2017, 05:43:54 PM
Earlier this year in Free Flight Quarterly, Sergio included an old magazine article on Norman Getzlaff
describing his thermal detection system and his FAI power model 'Amen'.
I've attached the two 3-views included in the article.
To say it's an unusual design is an understatement, but I noticed something in the text which isn't shown on either drawing.
Quote: 'The stab has 1/16" washin on the left side with the right side trailing edge up 1/4". '

While this not the only pylonless design I've seen, it's the only time I can remember stab warps like this.

Bearing in mind that the wing had no warps and the motor 'has a .004" shim to the right to counteract torque',
and it was intended to climb absolutely straight, I've been trying to work out the effect of the twisted stab.

Anyone got any ideas, or does anyone know any more about this design?


Title: Re: Amen
Post by: FF Bruce on June 25, 2017, 07:02:59 PM
I believe Ed Bellinger the designer of the "GYSOB" record holder in the 1970's told me of this model and that it was the influence for the first Gysob. Hard to see it in his finial design but if you where to look at a side view of the Gysob you can see some of it. Ed flew his models as straight up as any model I have ever seen,trail edge was all you saw for 15 sec. As for the wraps I guess what ever works.       

Title: Re: Amen
Post by: danberry on June 25, 2017, 07:32:51 PM
The warped stab will induce a rolling moment.
And nightmares. Don't forget nightmares.

Title: Re: Amen
Post by: faif2d on June 25, 2017, 08:54:49 PM
There used to be a gentleman in Chicago named John Rak.  He flew a high thrust model called the spearman or something like that.  It was a F1C model that went straight up, power was a Super Tiger .15,  and when the motor quit it would pop over into the glide path.  Really quite impressive!

Title: Re: Amen
Post by: RobinB on June 28, 2017, 03:10:26 PM
Can't argue with Dan about the roll, though I'm not sure what a roll emanating from the tail would do. No pylon to act as a vane / damper, either.
To add to the weirdness the stab warps would roll it clockwise (viewed from the rear) - I think - but it has tilt for left glide.
How it sorted itself out when the engine cut is difficult to imagine.

Apparently it collected four first and two second places one year, so it must have worked.