Holbeach

P-51. Bashing the oleos to watch the animation. Some say; "the oleos are too bouncy", so lets bash the landing. The bumpiest airfield on the Channel map, is the place to watch oleo travel. Rochester Aircraft Factory. Good strut travel, but are they too soft? .. Runway 16. 2926'. You can't land here with the Mosquito, there is not enough strut movement to absorb the bumps. ..

Ahh the good old 633 Squadron, back in '64. 8 Mossies used in this film, all ex target tugs, sold into civilian use. All were stripped of military gear, guns etc, and are therefore very lightweight. One was sacrificed for the cause. With a long runway, (Inverness Airport), and a dramatic film to produce, a wheelie was the best choice, as are the museum pieces at airshows. Some good shots of the gear struts though. ..

One thing I can't find, is any kind of damping system for the strut. Maybe the rubber deforms and reforms slowly, but there is no dedicated system, such as the Ferodo friction damper, seen in the tailwheel, which also has rubber blocks, (5). Here's what my WW2 pilot says about his first flight in a Mossie. This is represented quite well, according to goggles wearers, but as an unpleasant experience. ..

Full load 20500lb (22500lb in DCS) minimum is 1.75 inch. Plus 20mm is 2.6 inches of tube showing. I'll take that. Min load 14000lb (16000 in DCS) minimum is 3.0 inch. Plus 20mm is 3.79 inches of tube showing. I'll take that. ..

To me visual is very important. If I lower the flaps 40 deg, I don't want to see 20 or 30 deg, I want to see 40 deg. If the srut should be 2'' I want to see 2'' not 8'' and a strut like a Stork legs. If it don't look right, it ain't right. ..

@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.) That's right. Adding say, 4000lb. fuel and water should compress about 1'' of tube. BUT: You have to start with about 16000lb. of airplane already sitting on the struts, so you should start loading at about 2/3 inside the strut, not 8'' exposed. ..

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. .. Thanks. ..

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. ..

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. ..

@SMH Please post your Mustang landing gear video in here. Thanks..

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.. ..

I spent all Sunday morning forming a bug report with a detailed explaination and none of the text showed up, just a load of pictures. What a FWOT that was. A howling 7 deg Norwester with stair rods outside, I might as well start again, in stages this time. ..

Excellent videos on the main gears. They show exactly what's good about the P-51 and bad about the Mosquito and why it collapses the struts so easily on landing. I'll do a bug report later on the Mossie. The real manual says if the Mustang gear is too bouncy, then it's lacking damper oil. Ours is simply lacking in damping and needs sorting. But, it has correct shock absorber travel and only bounces due to lack of damping after a hard landing. The Mossie on the other hand has almost no travel and should have a least 6 inches after landing, leaving only 2 inches tube showing. ..

I'll be doing a bug report soon on the Mossie main gear as it spoils an otherwise great plane. The tailwheel jig is already reported. ..

P-51 at Eastchurch and my first landing at Biggin Hill with Mosquito. This was the moment I realized what was so right about the Mustang and so wrong about the Mossie. (Looking at legs actually).. ..

Mosquito has 11 of these blocks, plus a half block, separated by spacers, plus a rebound block, in a stack inside the tube.There is no air or oil involved. They produce 8 inches of travel. 2 inches of tube showing under compression and 6 inches above inside strut, when static at 20000 lb.. They have friction dampers. Pneumatic Drum brakes. The Mustang has air over hydraulic dampers. They are pumped up with a compressor through a tyre type valve to give 3.5 inches static oleo clearence. (2 inch in later H model). Hydraulic Multiplate (19) disc brakes. P-47 Aerol strut similar to P-51. Hydraulic Drum brakes. The Spitfire has air with friction dampers. Pneumatic Drum brakes. No coil springs involved in any of them. ..

See my previous post after watching your track. ..

I took over your track when I noticed you've only altered 1 brake axis. You have to do both. You had left brake permanently on. Right brake was OK. I corrected brake, taxied, took off and landed normally. Couldn't do anything about the music though. ..

Mustang brake .trk Pity that track wasn't Caucasus, I would have liked to have seen it. My brakes are exhibiting the same characteristics in all my toe brake aircraft and I've not noticed it before because it has little effect on nose wheel planes. Maybe, my end, problem. Track shows brakes default axis. Notice instant jump to half power. With regards to the soft oleos, I ran it down a concrete runway and was able to rock it from side to side, rolling like a boat as if the oleos had no damping as they extended fully. ..

Here's what I found with some ground running with 30 % fuel. The tailwheel is connected to the rudder at a ratio of 5 to 1, so with full deflection of 30 deg, the tailwheel will be at 6 deg and it looked spot on to me and taxi steering was good. Locked and with brakes it will do donuts with the wheel skidding sideways at neutral stick. Unlocked, the wheel swivels to 90 deg and going backwards it swivels to 180 deg At full load this might all be different. ..

High pressure air and hydraulic oil. They feel like an old American car of the same era, on springs and no dampers. ..

Either of these will work, but the axis tune doesn't break my golden rule. Neither of them will alter the 50% instant application of brakes, but with this reduction in power, it doesn't matter any more ..

Some of us have a stuation where the brakes come on instantly to 50%, which causes prop damage and is therefore unusable. You don't seem to have this problem. The tailwheel should have 6 deg max from centre, (which isn't much), and is only meant for near straight running with the stick pulled back. ..

Manual says, don't do a stall landing at this weight, (70% fuel), but with the new squidgy legs it works out quite well and means no bouncing and a straight rollout. ..

Ok. I've got a work round. Brakes still come on instantly to 50%, but with Saturation Y at 62% on a slider I can now use the brakes without breaking my nose. I have'nt flown the Mustang for many years, so it's off to Eastchurch to see how high the pony jumps. Luckily the gear horn sounded on very short finals, which avoided an embarrassment, but apart from that the landing was straightforward and much easier than the Mosquito. The wheel animation also needs sorting, as reported. Time for some circuit practice. Update: 62 was still too much braking power, so I've reduced it to 50 Sat Y. Full braking is available without a broken prop and rollout steering is easier. ..