fixed Mosquito landing gear strut incorrect operation..

[Holbeach]

Mosquito, main gear shock absorber diagram.

11 rubbers absorb the landing shock. There is max 8'' travel, all of which are available for absorbing landing shock. There should be approx 2'' telescopic tube showing, when static. There are no hydraulics, pneumatics or coil springs involved and no maintenance is required.

Only when the closed static tube length is less than 1.75'' at full load, do the rubbers need replacing.  

The lower part of the strut at X--X should be below the wheel rim, when static.

 

Like this.

 

And this. Our Mossie in 2021. Correct attitude and tube extension.

 

After update. Max weight for landing and correct 8'' extended.

After landing this tube should have retracted by 6'' but it's still fully extended. It's sitting at 12.4 deg which is correct for a fully extended gear.

Instead of the 8'' shock absorbtion usable on landing, you get about 1'', (nicely shown in SMH video), so most of that load is taken by retraction tubes, which then collapse.

Additionally, instead of the 11 deg attitude it should have, it is now 12.4 deg, which makes a higher drag on a 3 pointer, a sudden drop onto the mains, a bounce, then a hard hit on the 2nd landing, slamming the poor little tail wheel into the deck.

Correct attitude.

Incidentally, this aircraft was lost when filming a TV guided glide bomb, dropped from a B-17 on Le Havre. The bomb exploded on contact with the ground and brought the Mossie down. The pilot, below, survived, but the cameraman didn't make it.

Correct extension. With  Leather gaiter.

 

Incorrect extension. Full 8'' still showing. This is the exact same image of the 2021 replay track shown earlier, but the update has now been applied to it..

No matter how hard you hit the pavement the strut won't compress more than 2''. The strong spring acts like a Pogo stick to bounce you back into the air. There is good tyre deformation, but this probably adds to the overall bad situation.

It should stay where it's put and gradually sink as the speed drops off and the weight comes on, until most of the tube is inside the strut.

As it is, adding 5000lb to each strut has no effect and it acts as if the rubbers are solid.

Interlude...

I7 2600K @ 3.8, CoolerMaster 212X, EVGA GTX 1070 8gb. RAM 16gb Corsair, 1kw PSU. 2 x WD SSD. 1 x Samsung M2 NVMe. 3 x HDD. Saitek X-52. Saitek Pro Flight pedals. CH Flight Sim yoke. TrackIR 5. Win 10 Pro. IIyama 1080p. MSAA x 2, SSAA x 1.5. Settings High. Harrier/Spitfire/Beaufighter/The Channel, fanboy..

 

..

Edited May 1, 2024 by Holbeach
Moved from P-51 forum..

[Holbeach]

@SMH

Please post your Mustang landing gear video in here.

Thanks..

[Lixma 06]

Few inches compression at most, and practically zero while parked.

[SMH]

56 minutes ago, Holbeach said:

@SMH

Please post your Mustang landing gear video in here.

Thanks..

Here you go. Included the other two as well for comparison.

 

 

 

[Skewgear]

Ca  somebody please be so kind as to record a video of a Mosquito landing that shows the main gear compression, and capture the track file, and upload both here together?

That helps the fault finding process. If the root of the bug is that the gear is simply too stiff and unyielding, that can be reported internally.

[SMH]

47 minutes ago, Skewgear said:

Ca  somebody please be so kind as to record a video of a Mosquito landing that shows the main gear compression, and capture the track file, and upload both here together?

That helps the fault finding process. If the root of the bug is that the gear is simply too stiff and unyielding, that can be reported internally.

Here's the tracks for my videos above. (I greased the landing though so maybe not the best example.)
 

Mosquito_New_Suspension_Test_04.trk P-47_New_Suspension_Test_01.trk TF-51_New_Suspension_Test_01.trk

Edited April 28, 2024 by SMH

[Lixma 06]

Couple of landings (don't rate them) - first one is default config, second was carrying the heaviest loadout + max fuel. The suspension doesn't appear to notice the extra weight. TRKs attached.

 

 

mozlandg2.trk mozlandgheavy3.trk

[SMH]

Good illustration of the fragile tailwheel in that second clip. 

[Terry Dactil]

I always thought that the landing gear compressed to absorb the downward force of the landing and then was higly damped on the return stroke so as not to bounce you back where you started from. This lot may just as well be a big spring with no damping at all.

I have great admiration for ED's programmers for their fantastic graphic skills, However, I am starting to think that there is a lack of experience how real aircraft handle in the real world. After all, there are not too many Mosquitos left in the real word for just anybody to fly. 

 

 

[NineLine]

Mossie already has some gear issues reported and being looked at, just as an FYI.

[Slippa]

9 hours ago, 4eyes said:

Thank you for looking into this!

Definitely. Thanks, to everyone for the proper inspections.

I’m amazed at some of the stuff I read on here. Technical knowledge and research on a level beyond me a lot of the time. Much appreciated though. 

Glad to read someone might be trying to get our Mossies sorted. As slow as it is, I love it but it really does need servicing so thanks for taking a look devs and good luck with it.

 

[Slippa]

On 4/28/2024 at 11:14 PM, Skewgear said:

Ca  somebody please be so kind as to record a video of a Mosquito landing that shows the main gear compression, and capture the track file, and upload both here together?

That helps the fault finding process. If the root of the bug is that the gear is simply too stiff and unyielding, that can be reported internally.

Any suggestions on what I could use to record videos? I use a Mac/Bootcamp/Windows10/DCS and haven’t used anything video related, not gameplay videos anyway. Must be something free that’ll do it? What’s everyone using?

[Lixma 06]

41 minutes ago, Slippa said:

Any suggestions on what I could use to record videos? I use a Mac/Bootcamp/Windows10/DCS and haven’t used anything video related, not gameplay videos anyway. Must be something free that’ll do it? What’s everyone using?

Not sure how your setup works - but I just use Radeon Adrenalin's native recording thing.

Win 10 has it's own version (this is from a Google search)

• Windows key+G: Open Xbox Game Bar.
• Windows key+Alt+R: Start or stop recording.
• Windows key+ Alt+G: Record the last 30 seconds of screen activity.
• Windows key+Alt+B: Turn HDR on or off.
• Windows key+Alt+PrtScn: Take a static screenshot of your screen activity.

[Holbeach]

On 4/28/2024 at 9:37 PM, SMH said:

Here you go. Included the other two as well for comparison.

 

 

 

Well played.

Yes, I meant all videos from your Mustang thread and are a good example of how to do, the FM, wrongly in completely opposite directions.

 

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Edited April 30, 2024 by Holbeach

[Holbeach]

Trying to heavy land  to see how much the strut will absorb.

After weeks of landing without damaging the gear, I'm now trying to land heavy in order to see strut tube deflection without gear collapse. It's more difficult than I thought.

4 landings. 1st a nice wheelbarrow bouncing effect 2nd shows good tyre deflection when sideways. 3rd shows an attempt at wheely, at max load, which runs out of runway, 4th is light load 50% fuel and a standard 3 pointer. (Trakir reversed on touch down when the sun came out, so I did the roll out staring at the tail).

Max tube use was about 2 inches, any harder and the gear strut would collapse.

For scale the wheel rims are 16 inches.

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Edited May 1, 2024 by Holbeach

[SMH]

That behavior actually looks and feels pretty reasonable to me, @Holbeach. Remember that those big, soft tires take up a lot of shock too. But if I understand correctly, I think you also say there's no compression at all when just sitting there at maximum weight? I'm going to run a test to verify that; fuel and arm up while I watch the struts, to see if we get any compression out of them. (Or the tire, but I haven't observed any tire deformation/sinking in the Mossie yet so I'm not sure it's modeled at all, internally or visually.)

It's the fragile tailwheel that's my big issue with the Mossie, currently. The mains seem about right (though I would expect *some* compression under static weight - again, will try to test for that). 

Oh and someone was talking about bouncing in one of these threads. Planes definitely bounce when landed too hard! And with a taildragger, that makes your tail fall regardless of what you might be doing with the elevator, which makes your nose go up, which increases angle of attack, and then you start flying again into the next bounce! While 2 wheel landings are possible, the safer/easier way is to just stall them onto the runway from a couple of inches above it for a 3-pointer. (Like you do quite nicely a couple of times in that video.)

One more thing I just noticed at about 1:22 in your video. The wheels are braking after they bounce off the runway instead of free-wheeling like they should. You sure you don't have a bit of brake stuck on?

Edited April 30, 2024 by SMH

[Lixma 06]

I can't realistically land with a lower sink rate than this...

...and yet the plane rebounds into the sky like an electric shock, and thus begins the inevitable rodeo session.

[SMH]

59 minutes ago, Lixma 06 said:

I can't realistically land with a lower sink rate than this...

...and yet the plane rebounds into the sky like an electric shock, and thus begins the inevitable rodeo session.

Yes you can. Hold it off the runway as close as you can without touching down and then completely chop power. She'll settle into a 3 point landing at a much higher angle of attack and much slower speed. (Also, are your flaps fully down? I can't quite tell.)

Edited April 30, 2024 by SMH

[Skewgear]

13 hours ago, SMH said:

Yes you can. Hold it off the runway as close as you can without touching down and then completely chop power. She'll settle into a 3 point landing at a much higher angle of attack and much slower speed. (Also, are your flaps fully down? I can't quite tell.)

 

The point is that in reality the landing technique is to wheel it on and lower the tailwheel. You cannot do that with the DCS Mosquito - you can't fly it realistically - because of the bugs with the too-delicate tailwheel and that bizarre tail-down swing as soon as the main wheels touch, as Lixma's video illustrates well. Note that there's no stick-back input on the elevators at all.

[SMH]

7 hours ago, Skewgear said:

The point is that in reality the landing technique is to wheel it on and lower the tailwheel. You cannot do that with the DCS Mosquito - you can't fly it realistically - because of the bugs with the too-delicate tailwheel and that bizarre tail-down swing as soon as the main wheels touch, as Lixma's video illustrates well. Note that there's no stick-back input on the elevators at all.

There's a couple of near perfect landings in @Holbeach's video. You can absolutely 3 point land it, and you can land it without breaking the tailwheel, it's just way too easy to break it right now. 

[SMH]

So it turns out the Mosquito's struts do compress as the aircraft weight increases, just not by much. (Which I think is probably correct for this rubber block type of suspension.) Here's a track and 4x playback speed video to show the effect as we go from empty, to full, and back to empty.

Also included are tracks for the P-51 and P-47, which show this effect much more dramatically, particularly the P-51 (which, again, seems maybe a bit too soft and/or springy).
 

 

P-51RearmingStruts01.trk P-47RearmingStruts01.trk MosquitoRearmingStruts01.trk

Edited May 1, 2024 by SMH

[NineLine]

Hey all, just a small update I was told that there is some slight tuning of the Mossie gear coming down the line, so watch for it in an upcoming changelog and we can continue to discuss from there. Thanks all and I do appreciate all the conversation and testing on this, I really do. 

[Slippa]

Music to my earholes  .

Thanks one and all.

[Holbeach]

14 hours ago, SMH said:

There's a couple of near perfect landings in @Holbeach's video. You can absolutely 3 point land it, and you can land it without breaking the tailwheel, it's just way too easy to break it right now. 

Here is the reason I've always done 3 pointers right from the start and mostly use 1100 yd runways for practice.

High time RAF pilot, recalling his first landing in 1942.

 

Having said that, a wheelie should still be possible in DCS on a long runway, but from what I've read it doesn't go well.

 

..

10 hours ago, NineLine said:

Hey all, just a small update I was told that there is some slight tuning of the Mossie gear coming down the line, so watch for it in an upcoming changelog and we can continue to discuss from there. Thanks all and I do appreciate all the conversation and testing on this, I really do. 

Thanks.

..

Edited May 2, 2024 by Holbeach

[Shibbyland]

I don't feel too bothered about the visual compression or lack thereof but I do find the Mosquito in particular not very nice to land, far too firm on the ground. 

Not easy to judge sink rate visually on a 2D screen so part of it will be how I'm landing it but even then, wheel landings are mission and theyre arguably meant to be the easier form of landing.