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Re: [Jsbsim-devel] Fwd: Helicopter
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From: Simon J. M. <sim...@go...> - 2020-11-04 22:02:08
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For those that are interested... The flight model patch can be found here https://github.com/FGMEMBERS-NONGPL/UH-1 On Fri, 30 Oct 2020, 09:39 Simon Julie Morley, <sim...@go...> wrote: > Come on, it wasn't that hard a question > > On Tue, 27 Oct 2020 at 15:54, Simon Julie Morley < > sim...@go...> wrote: > >> I'm not a C++ coder I work on xml code. >> >> It's not a case of ignoring rotor functionality but more a case of after >> 10+ years of only working on propellers, (in fact the first time i touched >> a turbine was doing the avatar Scorpion gunship) I'm extremely familiar >> with how the to create propeller tables and how the propeller code works. >> >> To answer the next question, without using any equations describe in your >> own words the requirements of, and how flapping is implemented in a real >> life helicopter and I'll explain how I do it with a prop. >> >> Simon >> >> On Tue, 27 Oct 2020 at 13:50, Sean McLeod <se...@se...> wrote: >> >>> Hi Simon >>> >>> >>> >>> Are you adding code to FGPropeller to implement some of the >>> functionality that is currently in FGRotor but not in FGPropeller currently? >>> >>> >>> >>> Are there some aspects of FGRotor’s functionality that you’re ignoring >>> because you don’t think they’re useful for your needs? >>> >>> >>> >>> What things did you notice in FGPropeller that FGRotor can’t currently >>> do? Could potentially be useful to add them to FGRotor for users of FGRotor. >>> >>> >>> >>> What’s quite useful is Thomas references the equations etc. that his >>> code is based on, e.g. >>> >>> >>> >>> // Flapping angles relative to control axes /SH79/ eqn(32) >>> >>> void FGRotor::calc_flapping_angles(double theta_0, const FGColumnVector3 >>> &pqr_fus_w) >>> >>> >>> >>> <dt>/SH79/</dt><dd>Shaugnessy, J. D., Deaux, Thomas N., and Yenni, >>> Kenneth R., >>> >>> "Development and Validation of a Piloted Simulation of a >>> >>> Helicopter and External Sling Load", NASA TP-1285, >>> 1979.</dd> >>> >>> >>> >>> https://ntrs.nasa.gov/citations/19790005912 >>> >>> >>> >>> I’m currently using FGotor for the helicopter models I’m working on so >>> I’d be interested to know what you see as the pros and cons of using >>> FGRotor versus FGPropeller. >>> >>> >>> >>> Cheers >>> >>> >>> >>> *From:* Simon Julie Morley via Jsbsim-devel < >>> jsb...@li...> >>> *Sent:* Monday, October 26, 2020 10:09 PM >>> *To:* Development issues <Jsb...@li...> >>> *Cc:* Simon Julie Morley <sim...@go...> >>> *Subject:* [Jsbsim-devel] Fwd: Helicopter >>> >>> >>> >>> >>> yeh I have, and there's nothing in it I can't do with a propeller, and >>> actually there are things in the propeller code that the rotor can't do.... >>> so using rotor is a net less... >>> >>> >>> >>> Simon >>> >>> >>> >>> ---------- Forwarded message --------- >>> From: *Sean McLeod* <se...@se...> >>> Date: Mon, 26 Oct 2020 at 20:00 >>> Subject: RE: [Jsbsim-devel] Helicopter >>> To: Simon Julie Morley <sim...@go...> >>> >>> >>> >>> Hi Simon >>> >>> >>> >>> Have you looked at the FGRotor code to see what helicopter specific >>> stuff it models that isn’t modeled by FGPropeller? >>> >>> >>> >>> Cheers >>> >>> >>> >>> *From:* Simon Julie Morley <sim...@go...> >>> *Sent:* Monday, October 26, 2020 5:19 PM >>> *To:* Sean McLeod <se...@se...> >>> *Subject:* Re: [Jsbsim-devel] Helicopter >>> >>> >>> >>> Hi Sean, >>> >>> >>> >>> I'm not sure about using prop resulting in a lesser quality or that >>> rotor offering greater functionality... >>> >>> >>> >>> I remain open minded to the possibilities >>> >>> >>> >>> Simon. >>> >>> >>> >>> On Mon, 26 Oct 2020, 13:08 Sean McLeod, <se...@se...> wrote: >>> >>> Hi Simon >>> >>> >>> >>> I’m sure you can model a helicopter using FGPropeller etc. as a basis, >>> but I would imagine it would be a 1st order approximation since there >>> are a number of dynamics that FGPropeller doesn’t model compared to >>> FGRotor, so FGRotor would more easily allow for a higher fidelity model. >>> >>> >>> >>> Cheers >>> >>> >>> >>> *From:* Simon Julie Morley via Jsbsim-devel < >>> jsb...@li...> >>> *Sent:* Sunday, October 25, 2020 11:59 PM >>> *To:* Development issues <jsb...@li...> >>> *Cc:* Simon Julie Morley <sim...@go...> >>> *Subject:* Re: [Jsbsim-devel] Helicopter >>> >>> >>> >>> Hi Sean, >>> >>> >>> >>> To be honest I wanted to try and see if I could make a helicopter using >>> the prop code, because I couldn't see why not. >>> >>> >>> >>> On Sun, 25 Oct 2020 at 21:12, Sean McLeod <se...@se...> wrote: >>> >>> Hi Simon >>> >>> >>> >>> I’m just getting started again in terms of looking at JSBSim based >>> helicopter models. >>> >>> >>> >>> Thomas Kreitler improved the FGRotor model between 2010 – 2012. >>> >>> >>> >>> >>> https://github.com/JSBSim-Team/jsbsim/blob/4840a621dafe1ce64970990ddaec3e86a1c7e082/src/models/propulsion/FGRotor.cpp >>> >>> >>> >>> He also added a fairly detailed helicopter model for the AH1S: >>> >>> >>> >>> >>> https://github.com/JSBSim-Team/jsbsim/tree/4840a621dafe1ce64970990ddaec3e86a1c7e082/aircraft/ah1s >>> >>> >>> >>> In general there are very few JSBSim based helicopter models around when >>> I last looked. >>> >>> >>> >>> Cheers >>> >>> >>> >>> *From:* Bill Galbraith <bil...@gm...> >>> *Sent:* Sunday, October 25, 2020 8:08 PM >>> *To:* 'Development issues' <jsb...@li...> >>> *Subject:* Re: [Jsbsim-devel] Helicopter >>> >>> >>> >>> Simon, >>> >>> >>> >>> I had devoted some brain cells towards that idea a while ago, but never >>> implemented it. >>> >>> >>> >>> Imagine a point mass, with a point vertical force located above it. At >>> 50% collective, vertical force equals weight. Cyclic tilts that vertical >>> force fore/aft, left/right. Displacing the cyclic yields a slight loss >>> (sine of angle) loss of lift, requiring slightly more collective. >>> >>> >>> >>> The painful part comes when you try to fly it with a joystick. When you >>> release the joystick, the cyclic returns back to neutral, the aircraft will >>> slow to a hover. You basically need a joystick that has a trim lever, or >>> allows you to reestablish the trim point. >>> >>> >>> >>> Enough to get your brain cells excited? >>> >>> >>> >>> Bill >>> >>> >>> >>> *From:* Simon Julie Morley via Jsbsim-devel [ >>> mailto:jsb...@li... >>> <jsb...@li...>] >>> *Sent:* Sunday, October 25, 2020 1:41 PM >>> *To:* Development issues <Jsb...@li...> >>> *Cc:* Simon Julie Morley <sim...@go...> >>> *Subject:* [Jsbsim-devel] Helicopter >>> >>> >>> >>> Anyone here ever done one ? >>> >>> >>> >>> Want to talk about it, share knowledge ? >>> >>> >>> >>> Simon >>> >>> >>> >>> >>> >>> >>> >>> _______________________________________________ >>> Jsbsim-devel mailing list >>> Jsb...@li... >>> https://lists.sourceforge.net/lists/listinfo/jsbsim-devel >>> _______________________________________________ >>> The JSBSim Flight Dynamics Model project >>> http://www.JSBSim.org >>> _______________________________________________ >>> >>> _______________________________________________ >>> Jsbsim-devel mailing list >>> Jsb...@li... >>> https://lists.sourceforge.net/lists/listinfo/jsbsim-devel >>> _______________________________________________ >>> The JSBSim Flight Dynamics Model project >>> http://www.JSBSim.org >>> _______________________________________________ >>> >>> |
