Unfortunately, though, it should be able to reverse quite happily while on the ground. The trouble we were getting was that on startup, this would often happen as well. In fact, while testing it I was getting not only rearwards tipping but also nose-down into the ground. Seems to be a bit of a stability issue while on the ground?
C-27J Spartan
- Thread starter jojohnson9
- Start date
warchild
Charter Member
Yup.. Thats why i moved the CG forward by a foot. But moving it any further forward and we'd never get off the ground, or if we did, it wouldnt be for long.. The plane was weird in that regardless of how i mutalated the CG, it remained nose heavy. I even mutated the wheel base into something reminiscent of a stretch limo and it was still nose heavy( The CG sits between the foward and rear wheels on the main gear ). After matching the air file with the config file, and finding no solution, i put the CG back forward and threw my hands up. this plane just wants to be nose heavy, but with enough mass to shift backward and tip you up on your tail..
Part of the issue is the FAA numbers. Minimum on ground Beta is -17 degrees. That translates into reverse beta in the FDE also bbeinng -17 degrees, and this produces so much thrust that inertia takes over and stopping becomes a real adventure in reverse.. The only way I have found to successfully stop the bird while its reversed, is to use forward thrust or idle on the engines and void the brakes all together..
Pam
Part of the issue is the FAA numbers. Minimum on ground Beta is -17 degrees. That translates into reverse beta in the FDE also bbeinng -17 degrees, and this produces so much thrust that inertia takes over and stopping becomes a real adventure in reverse.. The only way I have found to successfully stop the bird while its reversed, is to use forward thrust or idle on the engines and void the brakes all together..
Pam
Victory103
SOH-CM-2025
warchild,
Finally got a chance to test your 2.1 at pretty close to ISA conditions with real WX downloaded. Speeds are much better and I did also have the beta (reverse) issues, but no problems on start with the engines, although on shutdown the props seems to windmill for a long time. Any changes to the roll spoilers? On the base 1.2, any roll input would also include the spoiler on that wing actuating, I didn't notice this on yours and my overall roll rate seemed slower. Flew a 2.5 test mission at FL210 with no problems, so the Spartan is for me at least now flyable.
Also noticed that flyers with the 1.2 .cfg will need to add both camera defs, fuel, and the 2 other models (EC and AC) to your file. Thank you for working on this, hopefully a 1.3 update comes out after the -15E release.
Finally got a chance to test your 2.1 at pretty close to ISA conditions with real WX downloaded. Speeds are much better and I did also have the beta (reverse) issues, but no problems on start with the engines, although on shutdown the props seems to windmill for a long time. Any changes to the roll spoilers? On the base 1.2, any roll input would also include the spoiler on that wing actuating, I didn't notice this on yours and my overall roll rate seemed slower. Flew a 2.5 test mission at FL210 with no problems, so the Spartan is for me at least now flyable.
Also noticed that flyers with the 1.2 .cfg will need to add both camera defs, fuel, and the 2 other models (EC and AC) to your file. Thank you for working on this, hopefully a 1.3 update comes out after the -15E release.
warchild
Charter Member
the current roll rate itself was chaned from previous versions. this was to bring the aircraft more in line with the actual roll rates seen on the real aircraft.. I didnt know anything about any roll spoilers. Those would be taken care of by a subsystem as they are not part of the flight model itself. With the problems we're seeing in the flight model being a conflict with one or more of Iris's sub systems, it is very unlikely that I will put out a 1.3 release. I do apologize for that..
Pam
Pam
jojohnson9
Charter Member 2016
Is IRIS planning an "official" update to this plane?
Hmm. Bought this one recently but after one attempt, it sits in the hangar in view of the several unreolved issues that have been highlighted. Had to resort the trusty old C-130 for "special ops" activities . .
Some cries for patches for new payware sometimes have more merit than others; this seems to be one that has merit.
Some cries for patches for new payware sometimes have more merit than others; this seems to be one that has merit.
As a former turboprop guy with a fair amount of turboprop time, I have to say I do like this model. I would like to throw in some real world info about the use of reverse pitch, although I have been hesitant up until now. I hate to see someone put the model away in the closet because of an operational misunderstanding. While it's true that the use of reverse pitch in this model will flip you over backwards (obviously real planes don't do that), it only does so if you mis-use the reverse.
Reverse in a RW turbo prop is really only effective at higher roll-out speeds, and your effective reverse braking diminishes as the speed lowers. For instance, if you touch down at say 120 knots and bring the torque levers into reverse, you're going to get an immediate and very noticeable "bite". Then as the speed lowers, the props lose their inertia and effectiveness, and as you get down to around 80-90 ish or so the reverse braking effect is over with. At this time you bring the torque levers out of the beta detent so you don't FOD out the engines. Even though the props aren't giving you anymore braking effect, they're still creating a wash onto the ground that can kick up FOD material. An important thing to remember here is that the fuel control unit uses a much lower fuel schedule once you bring the torque levers into the beta range, and that is why they lose their inertia.
The Iris Spartan will only flip over on it's back if you leave the props in reverse until you're almost to a full stop. Don't do that. That's not how it's done in real life. If you bring the torque levers out of the beta range when you get down to a fast taxi speed, you won't flip over.
Reverse in a RW turbo prop is really only effective at higher roll-out speeds, and your effective reverse braking diminishes as the speed lowers. For instance, if you touch down at say 120 knots and bring the torque levers into reverse, you're going to get an immediate and very noticeable "bite". Then as the speed lowers, the props lose their inertia and effectiveness, and as you get down to around 80-90 ish or so the reverse braking effect is over with. At this time you bring the torque levers out of the beta detent so you don't FOD out the engines. Even though the props aren't giving you anymore braking effect, they're still creating a wash onto the ground that can kick up FOD material. An important thing to remember here is that the fuel control unit uses a much lower fuel schedule once you bring the torque levers into the beta range, and that is why they lose their inertia.
The Iris Spartan will only flip over on it's back if you leave the props in reverse until you're almost to a full stop. Don't do that. That's not how it's done in real life. If you bring the torque levers out of the beta range when you get down to a fast taxi speed, you won't flip over.
During my one test flight of the Spartan, I never engaged the revesers. I am mindul of Pam - whose achievments and wisdom I have great respect for - and her on-going search for improvement with the flight model and it seems engine management issues. Am a bit of a turboprop junky myself (piston only so far flying IRL) and am very in tune with Bone's advice that they only bite at higher speeds. You need to spare your brakes at higher roll out after touch down and use reversers and later quit these and apply brakes as you get down to lower roll out speeds. A bit of tme (FSX) practicing this with the King Air, Turbo Commander, PC-12, F-27, C-130 Tu-114 etc. FS did not, as we know, model turboprops all that well but they still are noisy and fun in FSX as IRL!
papab
Charter Member
From Pam-
1. Push the gust lock forward to open the kneepad
2. on the knee pad, left click on autostart
3. return the gust lock to its normal position and close the knee pad.
4. on the left center overhead locate the apu switch and right or left click on it till it clicks two places up to "start"
5. wait for the two windows to the left of the apu start switch to display their full values.
6. move directly down below the apu start switch to the engine start knobs
7. click on each engine start knob till it rests in the start position..
8. breathe and relax. it takes a few seconds for the turbines to wind up..
The plane will lurch as the props spin up.. make sure to keep your parking brake on..
Pam
Only thing she left out(after #7)-- you need to turn on the fuel flow to each engine after you go to start. As I remember they are below the start switches at each end of the fuel panel on the ovehead and make sure the parking brake is on! Took me a while but got it down now...
Rick
Don't give up, it's actually fairly easy. You just need to know a few pertinent details....
DOH! Someone has very kindly reminded me about the all important gust lock/knee pad/autostart step. I did this the last and first ever attempt to start her and it worked! So that is sorted. Am a huge fan of FS turboprops and used start up grumpiness on other aircraft. Part of the excitement.
I am still a little concerned over the various FDE/engine issues reported here, i.e. not reaching specified climb rate and speed and also over taxing the engines, etc. Pam has worked hard to improve things. Which version of the FDE do people use and should I go for? Also, on my one test flight I had noticeably slow frames. Is there another mod around I may not be aware of that may help this?
I am still a little concerned over the various FDE/engine issues reported here, i.e. not reaching specified climb rate and speed and also over taxing the engines, etc. Pam has worked hard to improve things. Which version of the FDE do people use and should I go for? Also, on my one test flight I had noticeably slow frames. Is there another mod around I may not be aware of that may help this?
papab
Charter Member
Victory103
SOH-CM-2025
expat,
Still working the 2.1 FDE by Pam until I hope the official 1.3 patch/hotfix/whatever comes out from Iris. It's out of the hangar in my sim finally, still testing and so far works great for low/mid level stuff.
Still working the 2.1 FDE by Pam until I hope the official 1.3 patch/hotfix/whatever comes out from Iris. It's out of the hangar in my sim finally, still testing and so far works great for low/mid level stuff.
I know it's not 'normal procedure' for turboprops, but it's fairly standard for both the C27 and C130 to use reverse thrust to taxi backwards. Generally, it is seen in airshow routines as here (poorly labelled as an 'emergency descent'):
http://www.youtube.com/watch?v=G_7IZAJfsvY&feature=related
and on this one you can actually see the nose wheel lifting off the ground at the point where the aircraft starts to reverse:
http://www.youtube.com/watch?v=PavWKkixtSk
There are plenty of videos out there of both aircraft using reverse thrust for this purpose. It is also used to ensure sufficient take-off distance in a tactical situation, the following being taken from the C130T NATOPS flight manual:
8.7.2 Backing the Aircraft
CAUTION
Brakes shall not be used during backing operations because of the
possibility of the aircraft sitting on its tail and causing structural damage.
Note
Monitor engine oil temperature during backing operations. Use oil cooler
augmentation if necessary.
1. Ensure there is sufficient clearance to safely operate the aircraft and the maneuvering area is free of all debris
that could damage the propellers or injure ground personnel.
2. Conduct a thorough brief to include pilot feet placement, direction of turns (if required), and which
crewmember will direct the evolution from the cargo compartment. References for turns will be in relation to
the tail toward the No. 1 or No. 4 engine.
3. Position a crewmember on ICS at the rampcontrol panel, and open the rampand cargo door. This crewmember
shall provide guidance to the pilot during the backing operation to ensure aircraft remains clear of obstacles
and on the designated taxi surface.
4. Both pilots shall place their feet flat on the deck throughout the evolution.
5. Reverse propellers simultaneously.
6. Use forward thrust to stop the backward movement of the aircraft.
7. After backing, taxi the aircraft forward in a straight line approximately 5 feet to realign the main landing gear.
It also reccomends moving the throttles from ground reverse to ground idle detent by 30 kts on the landing run.
http://www.youtube.com/watch?v=G_7IZAJfsvY&feature=related
and on this one you can actually see the nose wheel lifting off the ground at the point where the aircraft starts to reverse:
http://www.youtube.com/watch?v=PavWKkixtSk
There are plenty of videos out there of both aircraft using reverse thrust for this purpose. It is also used to ensure sufficient take-off distance in a tactical situation, the following being taken from the C130T NATOPS flight manual:
8.7.2 Backing the Aircraft
CAUTION
Brakes shall not be used during backing operations because of the
possibility of the aircraft sitting on its tail and causing structural damage.
Note
Monitor engine oil temperature during backing operations. Use oil cooler
augmentation if necessary.
1. Ensure there is sufficient clearance to safely operate the aircraft and the maneuvering area is free of all debris
that could damage the propellers or injure ground personnel.
2. Conduct a thorough brief to include pilot feet placement, direction of turns (if required), and which
crewmember will direct the evolution from the cargo compartment. References for turns will be in relation to
the tail toward the No. 1 or No. 4 engine.
3. Position a crewmember on ICS at the rampcontrol panel, and open the rampand cargo door. This crewmember
shall provide guidance to the pilot during the backing operation to ensure aircraft remains clear of obstacles
and on the designated taxi surface.
4. Both pilots shall place their feet flat on the deck throughout the evolution.
5. Reverse propellers simultaneously.
6. Use forward thrust to stop the backward movement of the aircraft.
7. After backing, taxi the aircraft forward in a straight line approximately 5 feet to realign the main landing gear.
It also reccomends moving the throttles from ground reverse to ground idle detent by 30 kts on the landing run.
Victory103
SOH-CM-2025
There is a thread on here regarding some updates that Iris hopes to complete this year, needed upgrades to current products, the C-27J was on the list.
In the meantime you could get the 2.1 FDE update from warchild.
In the meantime you could get the 2.1 FDE update from warchild.
warchild
Charter Member
We did things a bit differently than normal with this plane. Usually when we turn over a flight model to a company such as Iris, we dont look at it again. Thats because the model is fully tested before it leaves our hands. But something happened on the Spartan that prompted me to make the decision to take direct control of supporting that flight model, as it was one of our products and would have never made it out the door in the condition it was released in. I do not know what David and Iris have planned for the upcoming 1.3 update for the Spartan, but i will continue to support the flight model for the next six months. Please understand, I am one person doing the mailing on this. And there are a great many of you.
Pam
founder/ceo Jade Island Flight Test Center
Pam
founder/ceo Jade Island Flight Test Center