Beagle Pup experiment

[IAHM-COL]

So Typical

Bomber going way above my head .....

[sanhozay]

here replace the total content of your aerodynamics file with this..

I'll try that, thanks. Useful technique, as is the glide experiment.

If I was you I'd swap out your suspension for mine as yours is a bouncy ball

But it does bounce round corners and it's already stiffer than yours at 2100lbs/ft compared to 1010lbs/ft. I agree it could be stiffer though.

raise the nose gear to -55... which will give you an alpha of 1.8degs...

OK, I'll try that. It may be that the main gear needs to be more splayed too. I know it sits too much nose down compared to photos. What's the range of AoA I should be aiming for?

You'll find your plane has a LIFT of 786.5lbs..... should be 1600lbs

Makes sense.

your LIFT2DRAG is 12.47.... too high.

What's a good range to aim for? I looked it up and it says 10.9 for a C172. Should it be close to that?

[IAHM-COL]

@bomber

I still don't get the trim to work

Like this, and without autopilot, this craft is a handful.

[sanhozay]

I found some useful performance data:

https://www.flightglobal.com/FlightPDFA ... 200659.PDF

I've summarised these in a spreadsheet and calculated expected KIAS and fuel flow in usg/h:

Beagle Pup Performance

These numbers broadly match the figures in here:

Beagle News, Volume 8

[IAHM-COL]

haha
Half an hour to make it to 10000 :eyeroll:

Yesterday I spun a Su37 to FL460 in less than 5 min with an AoA close to 50.

[SHM]

Haha

[sanhozay]

@IAHM-COL: When I've finished tuning, I was hoping you'd test the 11,700ft service ceiling by taking it to Innsbruck.

Getting out would probably be more interesting than getting in.

[IAHM-COL]

Shoot me a message. I'd love to do so
LOWI->LSGG could be a great way to test the new terraGIT scenery in Europe too
and a good flight to try out with the Cannis...

[sanhozay]

@Richard: can we cross-check some numbers?

My main sources are http://www.pilotfriend.com/aircraft%20p ... %20100.htm and http://www.bobthebeagle.co.uk/specifications/. (All the Pups are identical behind the firewall).

Wing area: You have 115.27. I have 119.5.

Dihedral: You have 7.27. I have 6.67. I measured mine in Blender using my 3D model but it was created from a dubious 3D view. Did you find a number, or did you measure?

Hstab area: You have 29.4, I have 27.5 + 10.9 elevator, but I wonder now if 27.5 is gross area.

Vstab area: You have 19.25,. Same story as above, I have 21.7 + 6.76 (rudder). Should probably be 21.7?

I don't know if your tail shape matters but it looks like you used the same dubious 3D views as I did and ended up with the same mistake that I later corrected. Note the shape of the rudder and the almost vertical line of the trailing edge.

[Richard]

Most of my figures have been revised because they were a little wrong, largely because when I originally did this I didn't have as much information as we currently have, just a couple of numbers from Simon and a dodgy 3view.

* Dihedral 6.13158; this was estimated from a 3view, and then tuned a bit.
* Wing sweep 3 degrees.
* Wing incidence I now have at 0; but adjusted the tail to 1.9 (leading edge down) take this into account for stability purposes however it's not going to be quite right - I did it like this after getting very confused about whether or not I needed to use wing alpha or FRL alpha for the coefficient base of all of the surfaces. I spent about 7 evenings tuning this to get the right pitching moment.
* Htail I now have 27.5 - which includes the elevator
* VStab - I now have 22.8, the slight difference is because I can't (easily) get the curvy bit at the bottom of the top part. I'm counting the entire thing as one surface including the bit underneath the FRL.

What's been driving me crazy is the incidence of the horizontal tail (and the aerofoil to use). I'm fairly certain now that it doesn't have an incidence, but that the wings are around 2.5 degrees (based on measurement and the Beagle Mag, volume8 comments).

It appears that most of my instability problems were being caused by sign problems with the stability derivatives, particularly the pitch damping (which I guess being inverted became a pitch wetting).