The A2A Simulations Community

Since loading the B17 I've had a hard time to taxi the aircraft ie. I've needed around 30" mp (rpm max) just to get the aircraft to move . Then when it was moving the differential brake(s) only had what could be considered a poor effect . Over all I couldn't taxi properly. Tonight I was talking on TS to a fellow B17 flyer & we compared his aircraft to mine. We noted that his aircraft was rolling at 20"mp with about 1700 rpm , whereas mine needed 30" mp and the rmp was less than 1500! First off I did a full overhaul but this made no difference. I still had a problem. I then uninstalled accusim (removed everything I could find including the dat file) and the B17. Note that I had the following loaded;
1. B17 aircraft
2. B17 Accusim
3. B17 Accusim patch 1.1

I then reloaded the B17 and only the B17 Accusim. When I loaded FSX the B17 taxi performance replicated my friend's . Next I loaded the B17 1.1 patch and this killed my taxi performance with an exact performance of my original problem. I've since uninstalled & only loaded the B17 and original accusim. To test I ran the mp to 25" & at YBAS (Alice Springs, Australia) I turned the aircraft 180 degrees on the runway! I haven't been able to do that before tonight. I'd appreciate any comments because I'd like to load the 1.1 patch but I don't want it to kill my ability to taxi.

Regards
Ian

Sounds like you may not have the engines configured right. If you're getting 1500RPM with 30", then you need to make sure the prop controls are full fine/forward/high RPM, you have the engine mixture set to Rich or AutoRich and that you've properly warmed the engine prior to trying to taxi. Also make sure you have "Enable Automixture" unchecked in options and all realism sliders fully to the right as that can cause erratic behavior as well.

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CAPFlyer
I need to clarify one set of figures because I have misled you. At 20" mp I was getting a bit less than 1500 rpm (these are the correct figures when I'm using the 1.1 patch). Sorry about that.

I have always had the prop levers full (100%) and mixture at rich to perform the taxi. The engines are warm and Auto Mixture has never been on (that I know of). The realism sliders are fully to right. I use FSX with Acceleration.

Note that if I do not apply the 1.1 patch I can taxi quite easily with mp at 20" to 25" and rpm around 1700+. It seems like loading the 1.1 patch is reducing my taxi performance with the aircraft needing a lot more power applied before it begins to move.
My observations so far;
Pre patch the aircraft will begin to move with mp at 20" to 25" (100% rpm)
Post 1.1 patch the aircraft will not move until at least 30" mp (100% rmp). Post patch the RPM is much lower given the same MP settings.

As the aircraft is loaded now (not patched) I can taxi quite ok. When not patched I can often turn without differential power being applied to outer engine(s).

In my testing I test at the same airport(s) as things like runway altitude could change the outcome.

Ian

One thing I had noticed after the patch was that if you put the park brake on then off the B-17 wouldn't require as much throttle to move

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Ron
B-17 AIRFRAME 710 HRS PLUS AND CLIMBING




GIGABYTE X58A-UD5 MB, INTEL I7 950, 12GB DOMINATOR-GT DDR3 RAM, WIN7 64, GIGABYTE SUPER OVER CLOCK GTX 560 TI 1GB GGDDR5 1000Mz, CORSAIR 850W PS, NOCTUA NH-D14,
TRACKIR 5 & TrackClipPro

You need one of these:

viewtopic.php?f=29&t=22023

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Snuffy

Tonight I flew with two B17 friends, one having his aircraft patched with 1.1 the other two of us had not applied patch 1.1. We noted for the patched B17 the MP needed to start the aircraft moving on the ground was somewhere close to 30" the other two of us only needed about 20" mp. This was the same as my patched aircraft prior to my reloading everything. One difference to note was that this aircraft was able to make turns while on taxi, which wasn't the case with my pre-patched aircraft. We think this warrants further investigation so we intend to patch one of our non patched aircraft & make the same observations.


Regards
Ian

If I recall correctly, using up to 30 inches of manifold pressure is not out of the ordinary to get the aircraft to start taxiing, especially when fully weighted down. The aircraft is fully within operating limits and you shouldn't have to keep 30 inches of manifold pressure throughout the taxi.

Regarding turns. The aircraft tail wheel is fully castoring, which is like the wheel of a shopping cart in effect. You need differential power (to turn left you would need engines 3/4 running at higher MP than 1/2), differential braking or bursts of power to get a turn established. You will have some authority when taxiing when simply using the rudder but it won't be nearly as effective as the methods mentioned above.

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CodyValkyrie

I always load light fuel or less and no payload because I usually do short flights so weight is not my aircraft's problem.
A constant 30" is the norm for me after I patch the aircraft, no matter what load I have on board. I accept that 30"mp might not be unusual for some aircraft loadouts.

Quote "Regarding turns. The aircraft tail wheel is fully castoring, which is like the wheel of a shopping cart in effect. You need differential power (to turn left you would need engines 3/4 running at higher MP than 1/2), differential braking or bursts of power to get a turn established. You will have some authority when taxiing when simply using the rudder but it won't be nearly as effective as the methods mentioned above." I have been aware of what you are saying.

After patching the B17 I can't turn sufficiently in a taxi, with ot without differential power, with free castoring tail wheel, with extra light load/fuel.

Something changes when the patch is applied and my aircraft instantly becomes difficult to taxi. At the moment it's no problem because I haven't applied the patch but I would like to have the option with the next patch on the horizon.

Thank you for your reply

Ian

I'll take a flight tonight with the B-17 and report my results.

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At 49,294 pounds I'm finding that I can indeed start my taxi with 20 inches PM. It actually happened on accident when I was warming up and didn't see the brakes were on. I was moving very slowly. I am finding however that I am starting off better with 25-30 inches MP and then holding it at a lower range while taxiing. While taxiing is a bit of a chore, it is no different than I remember. I am using version 1.1.

Can anyone else confirm the issues this customer is having?

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No just try and put the park brake on then off I have found this helps

_________________
Ron
B-17 AIRFRAME 710 HRS PLUS AND CLIMBING




GIGABYTE X58A-UD5 MB, INTEL I7 950, 12GB DOMINATOR-GT DDR3 RAM, WIN7 64, GIGABYTE SUPER OVER CLOCK GTX 560 TI 1GB GGDDR5 1000Mz, CORSAIR 850W PS, NOCTUA NH-D14,
TRACKIR 5 & TrackClipPro

I typically have 30" MP when I start my taxi which gives me just shy of 2000 RPM. I then
throttle back as necessary to keep the speed in check as I navigate the narrow, winding taxiways
of the 91st Bomb Group field at Bassingbourn. With 4 throttles I find it no problem at all to taxi
and turn, running the outside engines up while pulling back on the inside engines, just changing
the angle that my hand makes on the throttles.

The important thing, IMO, is to keep the forward motion at the speed needed to negotiate turns without
getting too fast of slowing to the point where you need to push the MP higher than the initial 30".

On the tighter turns I will also tap the brakes a bit to facilitate the shorter turn radius. As with most
things, practice, practice, practice makes for a better experience.

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Paul


i5-2500K @4.3Ghz OC - GA-P67A-UD7-B3 - 8GB Corsair 1600mHz

26' MP seems to be the magic number to start my taxi. That fits with what Cody and Paul have been saying. I always wind up applying and releasing the parking break during the startup/warmup, so Ron's method works too, though I didn't know I was using it.

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-mike

Having just upgraded from my old 32-bit system to a new machine mainly for FSX (i7, Win7 64bit, GTX570, 8GB RAM, etc, etc), it seems I've been 'struck down' with this bug also.

So far I have tried testing by reinstalling the B17, reinstalling only the 1.1 patch, then reinstalling patch 1.21, even clearing out the log dat file and changing airports (who knows) and there's no difference. The plane refuses to taxi even with the engines roaring at 30".

At around 33-35", the plane will very slowly begin to creep and backing off the throttle will see it lose any momentum very quickly. It's almost as if an invisible handbrake is holding it back. And yes, I've ensured that my brakes are not applied (I have the brakes mapped to the toe brakes on my rudder pedals). I've also tried cycling the parking brake on and off multiple times.

Any thoughts would be appreciated.

Thanks,
Harm

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ok hearing about this made me think. i had this aircraft from the beginning and it does take a bit more throttle to now get this rolling. agreed 100%. capflyer i have logged all my numbers and mine are way off from what you are saying. to even go a step further here's exactly what i did.

egmh airport +4c 185ft msl just updated to 1.21 50847lb light load with unfueled tokyo tanks.(i often fly very long legs. longest to date 13.7. gander to lorient france no-stop with bb tanks)
normal start. always start with parking brake on(that's ruled out). who cares the sequence. i start according to engine time to keep them even. all four started awaiting warmup i go through different throttle settings. rpm is co-pilots control(double checked 100%rpm). auto-rich. mp selector 8.

1. 20.6 mp =1140rpm
2. 25.6 mp =1301rpm
3. 28.3 mp =1402rpm....this is where my aircraft barely started rolling. even i slight tap on the brakes stopped it completely. even if it was differential braking. to get any good taxi where steering is needed 30'mp is needed or exceeded (weight dependent)