Beagle Pup experiment

[sanhozay]

I'm using full throttle, yes. Brakes off, then smoothly increase throttle. Putting two and two together from your post on engines, I suspect you are going to tell me that I should be setting a takeoff thrust using RPM?

[IAHM-COL]

can I get the takeoff RPM too
I push that thing till goes round, then I go run/

[bomber]

Just wanting to know if you were smoothly increasing the throttle that's all.

with regards steering... your rudder is linked to the steering, yes ?

[sanhozay]

Yes, smoothly.

For me, the rudder control is definitely steering the nose wheel in your FDM, it's just that it's only moving it a tiny amount.

I have acquired a Beagle Pup 100 checklist. I can't reproduce it here but a couple of figures to keep in mind are the quoted climb speed of just 65kt and normal cruise of 85kt at 2300rpm.

[bomber]

Sanhozay, would you consider a review of the engines and prop from our fdm's, we could maybe also work on the DRI's engine/prop combination as a proof of method.

I'll have a look at my keyboard.xml file and see if sometime in the past I modified it to link the brakes to the rudder.... clutching at straws here.

[Richard]

For all surfaces I've double checked and fixed the geometry (positions), the airfoils (the wing root was not identical to the tip), the dihedral and incidence of the wing, and the centre of gravity and mass/balance including tuning of the moments of inertia. I've tuned and adjusted Cl, Cd and AOA to get closer to Nick Lawson's AIAA paper - but I'm still a way off matching the figures (and I'm not sure why that is). In the interim I've added a fixed amount of 0.012319 to Cd to account for the missing drag - but this is a very blunt method and needs refining.

Uploaded a new release to my site: http://chateau-logic.com/sites/default/ ... 6-11-15.7z

From my flight testing (of my own model, which is never reliable) it seems still to be too performant even with the revised drag, but more worryingly I can get into quite a strange situation with an excessive amount of sideslip in turns and/or high pitch. I think my aero is still a bit twitchy in the pitch control - but at the moment I'm at a loss as to why.

[sanhozay]

Sanhozay, would you consider a review of the engines and prop from our fdm's, we could maybe also work on the DRI's engine/prop combination as a proof of method.

This sounds like a plan. The prop and engine are critical to all three FDMs.

I regenerated my prop and aerodynamics configuration with Aeromatic++ and everything is now well beyond the painful 500fpm climb out at 65kts that I believe to be correct. I'm going to be busy now until Friday but I'll get back to it then.

What's DRI?

[Richard]

After some feedback from Vincent I've put together a revised FDM with only 33% of the pitch moment due to elevator.

This needs testing. It certainly seems a lot less twitchy to me. This file is here http://chateau-logic.com/sites/default/ ... up-vsp.xml - just drop it in.

Of course if the general opinion is that this is better then I'll need to figure it out; rather than just taking 1/3rd of pitch moment as that's not a general solution.

[IAHM-COL]

@bomber

My video

Flying the T4T-beagle
AVAILABLE NOW

Notes:

***

[KL-666]

Hi Richard,

Wlbragg describes exactly my experience in all it's detail.

Maybe a little better. It doesn't seem to be too much authority, it is more like too little authority on the opposite side. When you make a pitch change it wants to continue in the direction of the pitch and you need to over compensate to get control again. That leads to a vicious cycle that I pretty much always end up loosing. I cant make an approach and flaps seem magnify it.

It is like a huge weight is set in motion rotating around the lateral axis. Setting it initially in motion is easy, but after that, the rotating weight is hard to stop, and over correction happens easy. At low speed it is at it's worst, with or without flaps. I can't tell if flaps make it even more worse.

My greatest suspect is that there is some huge effect calculated from a change in AoA (wing or hstab), which is hard to counter. Second i would experiment with the CG. Maybe it is too close to CL or too far forward. Too far forward can have adverse effects too, specifically in the area of sluggishness.

Kind regards, Vincent