Bob Daly and RadfordC are correct. The further aft of the main wheels the CG is the more like a ground loop is. For the most complete exposition of the calculations I've seen read: "Landing Gear Design for Light Aircraft" by Ladislao Pazmany.
RadfordC. Thanks for bringing in the link to that nice article. Bob, thanks for educating me.
The question that I still have is whether moving the CG more back from the main wheels will reduce tendency to nose over or not. That is where this discussion started, as we were trying to analyze why the Max noses over easily in a forced landing. Some said it is due to high engine mass line, some said it is due the axle getting stuck in an obstruction.
Bob Daly and RadfordC are correct. The further aft of the main wheels the CG is the more like a ground loop is. For the most complete exposition of the calculations I've seen read: "Landing Gear Design for Light Aircraft" by Ladislao Pazmany.
Remember you don't want to "move the CG aft". You want to keep it as close to the designed location as possible. Too far aft and you have pitch stability problems. Too far forward and you have problems getting enough control authority in pitch. Read the manual on weight and balance. Proper CG location is one of the keys to an aircraft that really flies well. If you are really worried about a nose over, you might consider a tri-gear version.
So I reckon there would be a squeezing force instead of a '45 degree force' on the sides of the fuselage floor you'd expect with the standard set-up. Would it not have to be re-inforced to react that squeeze?
Antoni, it is. With the optional 'steel undercarriage' there is an additional substantial steel crossmember transversely across the floor that braces the two u/c mounting points. Good deduction!
I guess the reason for tail lifting and airplane flipping on to its back when axle is force-stopped on landing roll, is probably because in a Max, CG is behind the main gear. In a plane where CG is ahead of main gear, the axle and main gear may shear off, but plane is not likely to nose over.
I dont think you cure a nose over tendency by moving the cg. The cg is fixed in relation to the centre of lift and that relation can not be disturbed.
You can move the wheels forward.The minimax wheels are already at the leading edge of the wing and way ahead of the cg. The criteria for wheel placement is ahead of cg in two point attirude which it is.The wheels cant be moved anyway. Also if the wheels are moved forward excessively it will be difficult to lift the tail while taking off. So moving the wheels forward may cure the nose over tendency but its not realistic.
So I guess other than the ski like device on the fokker spin trainer I posted earlier there seems to be no clear remedy other than avoiding landing in crops.
That wouldn't stop it from nosing over. The physics are simple and obvious. A big weight with a pivot point behind and below it rapidly brought to a standstill from 30 MPH. It doesn't take much thinking about. That is why I made enough speed so I could land into wind and UP THE HILL. It is the only chance you have to prevent a full flip.
>>>>I dont think you cure a nose over tendency by moving the cg. The cg is fixed in relation to the centre of lift and that relation can not be disturbed.<<<<
Totally agreed. My implication was never that we move the CG forward in a Max. I wouldn't even try it. Merely trying to analyze why it happened to Monte and a few others.
>>>You can move the wheels forward.The minimax wheels are already at the leading edge of the wing and way ahead of the cg. The criteria for wheel placement is ahead of cg in two point attirude which it is.The wheels cant be moved anyway. Also if the wheels are moved forward excessively it will be difficult to lift the tail while taking off. So moving the wheels forward may cure the nose over tendency but its not realistic..<<< ========================
I guess whatever changes you may make, in a tail-dragger the CG has to be always behind the main gear. So if that aft location of CG is indeed the prime reason to nose-over, then we simply live with the possibility.
Axle modification may reduce the chances of axle getting snagged in the undergrowth and big pieces of rock. But even that may not eliminate it fully.
Sorry to change the subject, but I've got another problem today. Those pesky blue FA18's are flying over my house again! I suppose it's not as annoying as the kidney stone I passed last night! Life is good.
If you ever fly an aircraft with the CG aft of the designed range (I have-not intentionally), you immediately realize that once it stalls it will probably stay stalled. Think riding a beach ball on a trampoline, stalling is not an option. On the plus side, you will go faster as the tail surfaces are now (must) provide lift instead of down force. I would bet the aircraft in the picture had a lifting tail. The Wright Flyer was more efficient because the canard configuration did not require a down force from the canard as a modern aircraft does with its tail surfaces. Joe
For ITMan496: If you are looking for two seats, potentially low maintenance, and fun, look for a 7AC Aeronca Champ. I have 800 hours in them. The Chief (11AC) (150 hours) is much nicer looking, side by side seating, and not nearly as much fun. You can always get as much or more than you paid for it if you maintain it and bought it wisely. Fuel consumption is slightly less than a 447 and you don't have to buy the oil. There is no actual TBO on the engine, according to Continental, if it pulls recommended static rpm, it is good to go. I have taken several 2000+ mile trips in one. Joe Scalet
My first plane, and the aircraft I learned on, was a 1946 11AC. Paid $12.5k, sold it 5 years later for $17.5k (did have some top engine work). Flew across USA twice. Once w instructor, once solo. Loved it, even though 65hp not a rocket ship two-up in summer 🙄😎. Super simple, super fun way to fly on 5gal/hr or less 👍.
Why focus on proving how great you are, when you could focus on becoming better?...
Guys, you're not going to be able to use a Hi Max gear like George makes, nor a Grove gear on a Minimax. The wing loads are carried by the landing gear assembly. If you don't like the straight tube then you need the welded version that TEAM sells.
Guys, you're not going to be able to use a Hi Max gear like George makes, nor a Grove gear on a Minimax. The wing loads are carried by the landing gear assembly. If you don't like the straight tube then you need the welded version that TEAM sells.
I know that.
And it's why if/when I build a custom Himax, it will be a Himax, not a Minimax.
I'm thinking a Himax, built to Eros specs, with a 503 DCDI, C box, 3-blade Warp Drive prop, George's main gear, etc. And two 6-gal wing tanks, with a 3 gal header tank.
And it's why if/when I build a custom Himax, it will be a Himax, not a Minimax.
I'm thinking a Himax, built to Eros specs, with a 503 DCDI, C box, 3-blade Warp Drive prop, George's main gear, etc. And two 6-gal wing tanks, with a 3 gal header tank.
Just about exact specs of my slow going project 👍😎
Why focus on proving how great you are, when you could focus on becoming better?...
Bigger tires would help prevent some of the axle grab I would think. Also give a little more cushion. But make it harder to stop in a short distance. How large of tires have people used?
Bigger tires would help prevent some of the axle grab I would think. Also give a little more cushion. But make it harder to stop in a short distance. How large of tires have people used?
I don't think that fat tires prevent you from stopping quick....
Not fat tires but large diameter makes braking harder. Think of a vehicle. If you put huge wheels on it the braking drops to nothing. Brakes are operating on small disc with huge force of wheels. You have to install bigger diameter disks to get braking back.
Will large tires alter the 3 point attitude / geometry of the airplane on the ground ? A couple of extra inches in diameter may not make a difference, but a 20 inch tire means axle will be lifted by 3.5 inches and may mean the nose tip being elevated by about 5 to 6 inches.
Not saying it will have an impact in ground handling, just asking.
( I was thinking of using a larger diameter tail wheel to get the nose down some, to make taxiing easier. )
Tire sizes I mentioned couple posts above, are external diameter of the tire when inflated. The stock wheel barrow tire is 13 inches.
The tire size they state for cars is the rim size, I guess. So in carspeak, the wheel barrow tire is only 6 inches. I hope this is a correct assumption.
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