Rising out of the Mud!

GYROX

Junior Member
Joined
Sep 20, 2006
Messages
11
Location
Larne Northern Ireland
Aircraft
MT-03 Gyroplane
Total Flight Time
330
Imagine the scenario - A gyroplane sits on a farm strip which has become a bit soft underfoot from heavy rain the previous day.
To add to the difficulties the grass has been left to grow a little too high for comfort and is still wet. Maybe the tyres on the aircraft are also a little soft.
The aircraft however is fitted with a decent pre-rotator which can take the rotor up to 200+ RPM. Also there is no wind...

My question is as follows - given this high ground drag environment how does the lift profile of the rotor effect the time to achieve an eventual take off?

In other words, does a rotor start to give partial lift at say 200 RPM so that as the aircraft moves off (somewhat laboring) across the soft ground, the aircraft becomes increasingly "lighter" and can slowly achieve full rotor RPM.(i.e. displaying a somewhat linear lift profile)
Or does the rotor have to be very close to full RPM before any noticeable lift is achieved and therefore the aircraft ends up wallowing along,hanging off the back of the drag curve, too heavy and sluggish and very unlikely to achieve enough ground speed to enable the rotor to attain full rotor RPM

Obviously variable weights of the aircraft (e.g. Fuel. payload etc) will magnify the effect but the principle I guess stays the same?

Regards to all on the Forum - this is my first posting
 
Norman

What you are describing is called a soft field Take Off. It has its own method of take off. When you attain the 200 RRPM the Gyro will have rocked back. As you add power place the cyclic slightly forward to get the nose back down your ground speed will start to increase get the cyclic positioned to balance on the mains. You will be lighter on the mains. Now you have mentioned the grass is high so the nose wheel will be slightly higher than normal but as you attain the proper ground speed the gyro will lift off slightly behind the curve. Imediatly push the cyclic forward to increase the air speed and you should be good to go to best climb out.


Hope this helps.


Thom
 
If it's a typical run of the mill gyro...he ain't gonna get airborne.

He might be able to run/taxi on the ground for awhile.

He needs airspeed to lift off the ground and with your scenario, he won't get the airspeed needed...IMO.


Cheers :)
 
I always prerotate to 200 rrpm, then start my takeoff roll, you still need the air speed/ground speed and the rotors will have to come up to around 280-300rrpm to get light enough to fly.
 
Screw-In

Here is a Soft Field Take-Off procedure as posted in a previous thread by Greg Gremminger:

Soft Field Takeoff: After the rotor indicates it is ready to fly - same as above - continue to hold the stick full aft as you smoothly increase power to takeoff power. Holding the stick full or mostly aft, allow the gyro to get light and lift off he ground as quickly as possible. When the wheels are off the ground, lower the nose as required to avoid climbing and keep close to the ground - "Digging it out". Dig it out in ground effect as close to the ground as possible, but definitely within 5 feet of the ground - rotor is more efficient in "ground effect". Accelerate in ground effect to best rate of climb airspeed and climb out at that airspeed. Avoid getting too high too slow in "Dead Man's Zone" - it also will not accelerate as well if it is out of ground effect. A soft field takeoff will naturally take more ground distance to accelerate - "dig it out" - when it is in the air - so this takes more open area than a Normal or Short Field takeoff - but you get off the ground quicker!

Screw-Out
 
Welcome to the forum, Norman!

Airfoil lift is a square function of airspeed (for any given AOA). What it means for your question is that, if your rotor 1-G flight speed is 360 RPM, at 180 RPM it generates about one quarter of the lift - i.e. one quarter of the weight of your gyro. Not all this lift is available for lifteing your gyro out of the mud because the rotor will be tilted back 20 degrees.

You get 90% of your full lift at 95% of full RPM. 80% lift at 90% RPM, etc.

Udi
 
I’ve flown many times from waterlogged sod strips with no particular difficulty. If there’s standing water, splash from the wheels will eat a wooden prop in no time.

I don’t think I’d be tempted to takeoff from axle deep pure mud, however.

Tall, dense grass will certainly bog down a gyro. We have a type of pasture grass used in Florida, Bahia grass, that is quite dense, tough and grows to waist height if not mown or grazed. I was once skimming this stuff when the drag became so great that I made an unintended landing. I suppose one could say it was sort of an arrested landing like on an aircraft carrier.

I’ve also taken off from soft beach sand. Aggressive throttle application is required and at a few mph, the tires get up and sort of hydroplane (maybe the word is sandroplane?).
 
Keep a watch out for large pieces of mud that could be flung up into the prop.
Another thing to watch is make sure your nose wheel isnt going to dig in !!
 
Thanks for all the comments - most welcome - (especially "sandroplane"!!)

Incendently I have just returned home from further training on my MT-03
"G-YROX" including my first solo flight yesterday! (for smiling picture see news section of www.rotorsport.flyer.co.uk )
 
Thanks for all the comments - most welcome - (especially "sandroplane"!!)

Incendently I have just returned home from further training on my MT-03
"G-YROX" including my first solo flight yesterday! (for smiling picture see news section of www.rotorsport.flyer.co.uk )

Hi Norman,

Slightly OT but saw you sailing north on the M6 2 weeks ago on a Sunday morning near Stafford in the mother of all thunderstorms! Even across the carriage way for that brief second, I have to say your new toy looks excellent!
 
M6 sighting

M6 sighting

Yes I guess it could have been G-YROX but it might have been Gerry having a shake down flight just prior to hand over
 
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Looks like they stole the plans for the Magni.

Scott


The Magni, ELA and the MT look like they all came out of the same box. All are way too expensive for what they are and I for one would like my passenger to be sitting alongside me instead of that bob sled arrangement!!

Still, they reputedly fly well and dont fall apart unepectedly so thats a bonus.
 
Scott - I guess they would be around $50-60,000 but email gerry at rotorsport uk for a more definitive answer.

Chopper - the idea of having the tandem seat arrangement(one behind the other) I guess is to allow better airflow to the prop and rotor disc therefore it should be a more effecient shape? - it also helps to lengthen the aircraft which assists in overall pitch and yaw stability
 
I'm with you Brian, I like the side-by-side arrangement better plus where I live having an enclosed machine would allow me to fly year round unless I wanted to dress up like an eskimo.

Scott
 
Scott - I guess they would be around $50-60,000 but email gerry at rotorsport uk for a more definitive answer.

Chopper - the idea of having the tandem seat arrangement(one behind the other) I guess is to allow better airflow to the prop and rotor disc therefore it should be a more effecient shape? - it also helps to lengthen the aircraft which assists in overall pitch and yaw stability


I agree, the tandem arrangement does allow better airflow to the prop etc however, an Australian designer here has I believe come up with a side by side cabin that has all the advantages of the tandem but with the advantages having your mate by your side.
I just think that if you are going to have a passenger, it would be a lot more fun having them by your side, the tandem thing to me is fairly impersonal.
 
I'm with you Brian, I like the side-by-side arrangement better plus where I live having an enclosed machine would allow me to fly year round unless I wanted to dress up like an eskimo.

Scott

I spent 1000 hours in an open framed machine and about 4000 in a pod with a windscreen so I have had plenty of 'breeze time' and would appreciate a cabin and mayby a heater. Boy, I am getting soft !!
 
Me too Brian:wave: :drama:

I found when I was looking at gyros to buy the Cabin type drew my attention while the open and pods look good but I thought of the winters and decided on a cabin.

Thom:peace:
 
cabin - no cabin

cabin - no cabin

I spent 1000 hours in an open framed machine and about 4000 in a pod with a windscreen so I have had plenty of 'breeze time' and would appreciate a cabin and mayby a heater. Boy, I am getting soft !!

fair point but I must say that the MT-03 windscreen is very effective. The only parts that feels any wind AT ALL are the outsides of my elbows (even cruising around at 80mph!) There is no need for a helmet visor and the view is unimpaired
 
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