Author Topic: A6M2 Glide ratio and fuel hits (Read 1010 times)

oboe · « **on:** March 11, 2003, 12:01:11 PM »

I can't seem to deadstick a landing in the A6M2. Once I lose engine power, it seems to drop like a brick. How could such a light airplane have such a poor glide ratio? Is it from drag? I thought the Zeke is a fairly clean a/c for a radial-engined airplane. The Ki.61 is a heavier aircraft but I found I can glide a long, long time in that plane.

Alos, is their a problem with the A6M2's damage model. Several times I've been hit and noticed a fuel leak, but my damage console indicates no damage. Anybody else notice this?

F4UDOA · « **Reply #1 on:** March 11, 2003, 12:06:15 PM »

Oboe,

On the glide ratio issue I haven't tested the A6M2/5 but it should glide well. What speed are you starting your glide from? I find that the best glide ratio is usally achieved at the same speed used for best climb. In the Zeke that is about 135MPH I believe. The aspect ratio is quite high in that bird and that usually means a good glide ratio.

Karnak · « **Reply #2 on:** March 11, 2003, 08:36:20 PM »

My experience is the same as Oboe's. The A6M is the hardest aircraft for me to deadstick a landing with.

GRUNHERZ · « **Reply #3 on:** March 11, 2003, 08:48:11 PM »

Yep that plane cannot glide worth a damn, Bf109 for example can glide much much better no matter what... This is odd because the zero is very light, has a high aspect ratio wing, and is very clean aerodynamically.

davidpt40 · « **Reply #4 on:** March 12, 2003, 05:14:07 AM »

Prop drag maybe? reduce RPMs

Batz · « **Reply #5 on:** March 12, 2003, 05:38:57 AM »

It makes no difference about rpm the zeke drops like a brick. reducing rpms does allow to glide better but its still a brick. Its very nose heavy even when landing under power. Its very easy to ding your prop.

ra · « **Reply #6 on:** March 12, 2003, 07:25:28 AM »

Same with the Typhoon and Tempest. I'd bet the problem is that all the other planes glide too well.

ra

oboe · « **Reply #7 on:** March 12, 2003, 08:31:57 AM »

F4UDOA - if you have a standard glide test to perform, I'd be interested to see the results of the A6Ms.

I don't any wingloading figures for aircraft, but would certainly expect the A6M2 to be one of the lightest loaded planes of all in the set. I would think that would translate to outstanding glide characteristics.

Glad to see others had noticed this too. I thought I'd lost it during my absence...

SKurj · « **Reply #8 on:** March 12, 2003, 09:19:24 AM »

I find when i drop rpm on the typh it glides quite well...

SKurj

funkedup · « **Reply #9 on:** March 12, 2003, 01:59:43 PM »

Glide ratio has nothing to do with wingloading or weight. Glide ratio = Lift/Drag ratio.

GRUNHERZ · « **Reply #10 on:** March 12, 2003, 03:53:52 PM »

Why does a bf109g6 then glide much better than a zero?

funkedup · « **Reply #11 on:** March 12, 2003, 04:35:54 PM »

Quote

Glide ratio = Lift/Drag ratio

F4UDOA · « **Reply #12 on:** March 12, 2003, 04:57:32 PM »

Oboe,

I don't really have a standard test but I can tell you in my test I climb as high as 20K throttle back and try to find a speed in which you can maintain a steady decent rate while maintaining airspeed.

This was much more difficult than I aniticipated.

I found a few things.

1. I could maintain approximately 85MPH while decending at 3K per minute. This weird because I was at a steep dive angle with the stall buzzer blaring the whole time. It seemed as if I was parachuting not diving. Even at a high dive angle I could not accelerate. Very strange.

2. I could maintain a 114MPH glide for a while at a 4K decent rate which again is strange because again it was a very sharp angle and it felt like I should have been accelerating. It had the feel of dragging something behind me like an airbrake or something.

3. I seemed to have the best sensation of gliding at about 160MPH to 140MPH TAS. However at this speed my decent was in excess of 4K per minute which I believe is too high and is more like falling than gliding.

However the biggest indication of something amiss was during the climb. My best climb speed at sea level when viewed on the digital viewer was 150MPH TAS at sea level increasing to 200MPH TAS at 20K. The best climb speed for the A6M5 according to TAIC data is 121MPH which mean the A6M2 should be the same if not less. Generally the best climb speed is the speed in which the wing generates the most lift as well as have the best thrust to drag ratio. Based on that the best glide is usually close to the best climb and our climb speed is way to high.

It seems our A6M2 has an unusual lift/drag curve which may prevent it from gliding as well as it should at the right speed IMHO.

davidpt40 · « **Reply #13 on:** March 12, 2003, 06:01:04 PM »

I got a 1k/min descent at 100mph in A6M2, full fuel, 2000feet cut engine.

dtango · « **Reply #14 on:** March 13, 2003, 06:02:12 PM »

Some food for thought:

[list=1]

What do you expect the glide ratio of a A6M2 to be? You should have this as a starting point before evaluating the FM.
Best glide performance / ratio is determined by best L/D ratio. L/D max for a given airframe is always the same regardless of a/c weight. This really throws folks- another one of those non-intuitive aerodynamic things. I'll spare the mathematical explanation of this.
Best-rate-of climb occurs "to the right" or at higher velocity than occurs at the best L/D ratio for prop planes. This is because the difference between power-available power-required is not at it's maximum at the lowest point of a/c drag. That being said velocity for best rate-of-climb is a good data point to get you in the ballpark for best glide velocity.
On glide tests here is a typical flight test method: use a constant velocity glide test repeated across a range of different velocities to determine your best glide velocity. Time how long it takes to cross a set altitude band (500 - 1000 ft is enough) at a given constant velocity. Multiply the velocity by the time to descend across the altitude band. Do this for the range of velocities you're interested in. Plot the time x velocity product vs. velocity. You'll get a parabolic curve. The peak of the parabolic curve will give you your best glide velocity. You can use the .set speed and alt-x functions to have your a/c maintain a constant velocity. Also your airspeed should be stabilized at constant velocity when you get your data so give yourself some altitude in descent to let your airspeed settle before you cross your test alt band.

Tango, XO
412th FS Braunco Mustangs