Having the prop aligned with the direction of flight was Bernie's idea, gathered from Dieter Siebenmann, I believe. He did get a good result on testing but I for one couldn't confirm it, so I went back to the usual set up and fared better! Derek Richards found on an EZB that having the wing at a positive incidence and probably with no downthrust built in gave very poor results.
Bob
----- Original Message -----
From: Bill Gowen
To: Indoor_Construction_at_yahoogroups.com
Sent: Tuesday, December 02, 2008 6:35 PM
Subject: Re: [Indoor_Construction] Re: Fwd: low ceiling high duration
Another problem I have with downthrust in the ordinary sense is that it puts an eccentric load on the prop shaft/thrust bearing assembly. I don't know how much of a problem this is in real life but it bothers me enough that I've used offset motor sticks occasionally to avoid eccentricity even from side thrust.
Back when I first started flying I was given the formula of "keep the thrust line parallel to the wing and get extra lift from the upthrust" when the model is flying nose high. I'm not going to say this is wrong because a lot of awfully good fliers use it, but keeping the thrust line in the direction the model is flying makes more sense to me. My understanding is that Bernie Hunt had good results with this idea on his whirling test rig.
Mark has had considerable success with his methods and I've had a little with mine so it could just come down to what you believe in and how well you apply your beliefs. I try to always start with making the model fly the absolute best it can and then use other methods to control climb and whatever other problems I have.
----- Original Message -----
From: RLBailey_at_care4free.net
To: Indoor_Construction_at_yahoogroups.com
Sent: Tuesday, December 02, 2008 1:20 PM
Subject: Re: [Indoor_Construction] Re: Fwd: low ceiling high duration
Mark
I certainly use stick bow to control the initial climb as necessary on F1D. What I referred to earlier was built in downthrust and I had in mind classes of model where this trimming device is not usable. Examples are models with very stiff sticks which do not bend appreciably even under full power.
Bob
----- Original Message -----
From: Mark
To: Indoor_Construction_at_yahoogroups.com
Sent: Tuesday, December 02, 2008 5:03 PM
Subject: [Indoor_Construction] Re: Fwd: low ceiling high duration
--- In Indoor_Construction_at_yahoogroups.com, <RLBailey_at_...> wrote:
>
> My own view - no downthrust on any class of model unless necessary to
trim the climb. I would only use it as a last resort.
>
> Bob
Bob, just wondering, do you not have considerable motorstick bow at
launch, esp. with F1ds? I depend on that (downthrust) for launch
control.
Mark F1diddler
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Received on Tue Dec 02 2008 - 11:11:01 CET