Mt 03....

[Aussie_Paul]

.....I had a chance to see a MT 03 yesterday. The 100 hp version.

Attached is pic of the head and a rear qtr view.

Aussie Paul. :)

[SamL]

I like the way the hub bar cones from the centre !!!!!!!!!!!

[Brent_Brown]

I would like to use that tail on my twinstarr

[C. Beaty]

The MT-03 looks to be a Chinese copy of the ELA-07 except ELA seems to do a better job of keeping the rotor stiff inplane.

[Aussie_Paul]

Any comments on the roll axis being to one side??

Aussie Paul. :)

[JRB549]

I caught a gyro on the Animal Channel last night that looked just like this one look. Any ideas it was in south Africa

[karlbamforth]

Any comments on the roll axis being to one side??

Aussie Paul. :)

LOL It took me half an hour looking at the pic to spot what it was you were talking about Paul. Answer I have no idea why it is like that.

[bones]

I know but not telling sorry(i think i know any ways)

[rtfm]

Any comments on the roll axis being to one side??

Aussie Paul. :)

Hi,
I took a photo of the rotor head during the recent Dannevirke fly-in (North Island, NZ) because it looked so weird, but I couldn't get it off my cellphone. I asked about it and was treated to a novel sounding explanation, which went something like this...

"Since the advancing blade experiences a greater airspeed than the retreating blade, there is assymetry of lift, which tends to roll the gyro to the left. By offsetting the axis, this tendency is overcome".

Which is why most gyros fly round in circles, I guess...

One would have assumed that the designers had heard of flapping, but perhaps I'm missing something?

Regards,
Duncan

[gyromike]

Hi,
I took a photo of the rotor head during the recent Dannevirke fly-in (North Island, NZ) because it looked so weird, but I couldn't get it off my cellphone. I asked about it and was treated to a novel sounding explanation, which went something like this...

"Since the advancing blade experiences a greater airspeed than the retreating blade, there is assymetry of lift, which tends to roll the gyro to the left. By offsetting the axis, this tendency is overcome".

Which is why most gyros fly round in circles, I guess...

One would have assumed that the designers had heard of flapping, but perhaps I'm missing something?

Regards,
Duncan

I wonder what the explanation would be if they offered an engine that spun the prop in the opposite direction?:rolleyes:

[bones]

Duncan is sort of close hehehe

[Aussie_Paul]

Ernie offsets the roll pin through the U block by a small amount. I understand that it is to have the airframe hanging against the prop torque.

Aussie Paul. :)

[enewbold]

"Since the advancing blade experiences a greater airspeed than the retreating blade, there is asymmetry of lift, which tends to roll the gyro to the left. By offsetting the axis, this tendency is overcome".

Thanks, Sam. Now I see it. The offset doesn't rotate; it's static. Interesting. The theory put forth earlier now makes a little more sense to me. =Ed=

[SamL]

Ernie offsets the roll pin through the U block by a small amount. I understand that it is to have the airframe hanging against the prop torque.

Aussie Paul. :)

Nice pick up Paul, interesting !!!!!!!!!!!!!!!!!!!!!

Sam.........:rapture:

[bpearson]

Same as the Rotax Magni. I think in another post Doug Riley said he didn't like it. Funny that my Subaru Magni doesn't need it.

[C. Beaty]

The sideways offset levels the airframe against engine torque. Some Cierva Autogiros used a sideways offset of the rotorhead for the same reason. But with a prop speed of 1700 rpm and a couple of hundred HP, torque level was much higher.

Ernie’s offset of the roll pivot reduces the need for sideways stick pressure against prop torque but isn’t enough to have much effect on airframe leveling.

Cierva’s later designs employed differential tailplane lift to balance engine torque and to level the airframe but that requires tail surfaces centered in the propeller slipstream.

[Doug Riley]

Didn't like what? Using the rotor to offset prop torque?

It's not the best way. In low G at full throttle, the prop torque is still there, but the offsetting rotor thrust isn't.

The Cierva tailplane idea is a more reliable anti-torque device. A full-span vertical fin can be used the same way.

[John Fonseca]

I think the ELA has the same set-up. They claim you need no correction to torque as you lift off. I don't know, I've never flown either.

John Fonseca.

[steveb]

The offset works OK. Most MTs seem to have a tendency to want to roll to the left in flight, so need a bit of right-stick pressure in the cruise. It's not a big deal as the stick forces are quite light. It also needs some right stick on take-off.

[C. Beaty]

The offset works OK. Most MTs seem to have a tendency to want to roll to the left in flight, so need a bit of right-stick pressure in the cruise. It's not a big deal as the stick forces are quite light. It also needs some right stick on take-off.
Sounds like it might be teeter bearing friction. Metal-on-metal teeter bearings normally try to lay the stick over to the left, forcing the pilot to hold right pressure.

Teeter bearings should be either Torrington style needle bearings or DU style plastic lined bushings.

[mceagle]

Most MTs seem to have a tendency to want to roll to the left in flight, so need a bit of right-stick pressure in the cruise. I agree with Chuck, it must be teeter friction. The torque reaction must be compensated for by the pilot but there should be little or no stick pressure required to do this. The stick is not holding the machine against torque - the rotors are doing that. the stick just changes cyclic pitch on the rotors.
In my opinion having an offset roll pivot is only a gimmic, which would lean the airframe the other way in engine idle or engine off conditions. The few in/lbs difference it would make would probably be negligable compared to the many other objects hanging assymetrically on the airframe (inc. the pilot)

[mceagle]

All the bolts on the head pictured appear to be 'black' plated - interesting

[steveb]

OK guys, now I'm confused. If Ernie or Cierva do it then it is to compensate against engine torque, if it's done on an MT then there's a problem with the teeter friction?

I realise that I'm at a disadvantage here because I just own one, whereas you guys have actually seen a picture ...... !:D

In my experience a tendency to turn isn't that unusual - you can trim it out on a VPM by changing the relative length of the two trim springs.

[bpearson]

I have not flown one but have been told by the owner of a VPM (early Magni) that had the engine changed to a Rotax that the machine needed roll input on the stick constantly even with the offset roll bolt.

The VPM/Magni has needle bearings for the teeter movement !

[C. Beaty]

OK guys, now I'm confused. If Ernie or Cierva do it then it is to compensate against engine torque, if it's done on an MT then there's a problem with the teeter friction?

I realise that I'm at a disadvantage here because I just own one, whereas you guys have actually seen a picture ...... !:D

In my experience a tendency to turn isn't that unusual - you can trim it out on a VPM by changing the relative length of the two trim springs.

Cierva offset the rotorhead as an experiment until he worked out differential tailplane incidence. No C-30 had an offset rotorhead. Nor did the similar but larger Kellett KD-1s.

Ernie doesn’t offset the rotorhead. The roll axle in the “U” block is offset perhaps 1/8” with large redrive Subarus where the tall tail doesn’t completely compensate for prop torque, mostly affecting sideward stick force.

Failure to aerodynamically compensate for propeller torque is yet another way to play Russian roulette with a gyro.

[Gyro_Kai]

The MT-03 looks to be a Chinese copy of the ELA-07 except ELA seems to do a better job of keeping the rotor stiff inplane.

I cannot leave this unresponded.
When two German Gyro-maniacs wanted to get an approved gyro in Germany, there was none. Ela and Magni were not interested in the appearantly difficult approval procedure. One of them owned a company that produces ultralight trikes. In their desperation (this is now my poetic strain) they purchased an Ela and copied it, with the changes that the German authorities requested (no I don't know what they were). So the MT-03 was created and is now almost a monopoly. Magni has the M14 and a weight reduced M16 called M14TT approved in Germany but is not really catching up.

Although I only have little more than 10 hours on my clock so far, I know that it does not fly in circles and the roll axis is just where it feels right :)

Kai.

[C. Beaty]

The expression; “Chinese copy” is merely an idiom that means unimaginative, piece by piece copy, Gyro Kai. I did not mean literally made in China.

The allegorical story goes that General Electric sold a turbo generator to an Asian country but one of the ship’s crew inadvertently kicked over a bucket of red paint during the voyage. When the copies began appearing in that country, the red paint splotch was perfectly duplicated. A “Chinese copy.”

[Gyro_Kai]

Ah, I see. In German we use the term "chinesische Billigkopie" translating as Chinese cheap copy. This refers to car break pads made of card-board etc.

The craftsmanship on the MT-03 is excellent but agreeably un-imaginative.

Kai.

[Timchick]

If it was built by Germans there's nothing cheap about it. They're some of the best engineers & craftsmen in the world. It doesn't matter if they were copying another design, it will be very well built.

[C. Beaty]

The prototype for all modern European gyros was the JT-5 by Juka Tervamaki of Finland.

Of all the clones, the Spanish ELA 07 has remained nearest to Tervamaki’s concept of propeller thrust line on or slightly below the CG.

If the MT 03 is a Chinese copy of the ELA, there is hardly a better model to copy.

Mr. Tervamaki is a well respected aeronautical engineer who received his introduction to gyroplanes from having worked for Bensen.

[Vance]

I don’t feel it is right to copy another person’s design without their permission or compensation. Design and innovation takes focus and that often involves considerable effort and pain. This is the reason for the concept of intellectual property.

Not having to do the work of design saves a lot of resources and gives the thief a competitive advantage.

In my opinion, the people who buy these products are participating in this theft.

Patent laws cannot protect intellectual property. Intellectual property is not easily quantified. The designer hopes that people will respect his property long enough for him to profit from his efforts. It is easy for the designer to be consumed in the defense of his property.

Thank you, Vance

[bpearson]

The prototype for all modern European gyros was the JT-5 by Juka Tervamaki of Finland.

Of all the clones, the Spanish ELA 07 has remained nearest to Tervamaki’s concept of propeller thrust line on or slightly below the CG.

If the MT 03 is a Chinese copy of the ELA, there is hardly a better model to copy.

Mr. Tervamaki is a well respected aeronautical engineer who received his introduction to gyroplanes from having worked for Bensen.

Are the results of the double hang test that prove this, available Chuck ?

[C. Beaty]

Are the results of the double hang test that prove this, available Chuck ?
I don’t know, Brian.

In the case of the JT-5, with all the bits and pieces in a pile, Tervamaki was quite capable of weighing each bit and calculating the CG to within a small fraction of an inch.

The easiest method of measuring CG is to weigh the machine at two different angles, compute horizontal CG in each instance and to calculate the crossing point. This demands accurate scales as well as an accurate clinometer since the angles are small. Ordinary bathroom scales aren’t good enough but commercial clinometers such as the “Smart Level” are fine.

I have a spreadsheet that performs the calculations if anyone would like a copy.

[bpearson]

I was refering to the ELA Chuck. The MT as far as I know has never had the v c of G tested as this isn't a requirement for sec T, which relies more on flight testing and this it obviously passed.

I would have thought there too many variables such as blade weight and fuel location to be able to determine if the ELA is CLT without doing the tests.

[Vance]

Hello Mr Beaty,

I would love to have a copy of your spreadsheet.

Thank you, Vance

[C. Beaty]

Vance, you remind me of one of those characters that attends trade shows pulling a child’s coaster wagon to hold all the literature he collects.

Nontheless, a copy will be on its way as soon as I receive your E-mail address.

[Vance]

Thank you Chuck.

I appreciate you generosity with your considerable knowledge.

I have spent a lot of time with a weight and balance spread sheet and computer drawings.

I use datum lines and then convert them to the center of gravity. I didn’t do well with pluses and minuses.

I have come within a couple of inches on the things I have built.

Center of gravity is important on a motorcycle.

I suspect that you have a more elegant way to do it.

I do love to collect information, but my laptop is my wagon.

When I am not struggling to rebuild I apply the things I have collected in my wagon.

I am nearly back on track.

Thank you, Vance

[Vance]

That is very cleaver Chuck.

I will try to make it work before Bensen Days.

I look forward to seeing you.

Thank you again, Vance

[StanFoster]

Vance: Hey....cant wait to talk to you at Bensen Days. Keep your dream alive pal. :)


Stan

[C. Beaty]

That is very cleaver Chuck.

I will try to make it work before Bensen Days.

It works now, Vance. There’s nothing you need to do except plug in numbers and it will spit out the answer in nanoseconds; assuming you have Excel or compatible spread sheet program.

The calculation sequence is locked so there is nothing you can do to hurt it. Any cell not highlighted in yellow can receive whatever entry you like.

The default numbers are simply a check on functionality. The attachment shows the default setting.

[bpearson]

Is this the method used to determine the ELA's v c of g ?

[C. Beaty]

Is this the method used to determine the ELA's v c of g ?
I don’t know, Brian, I don’t speak for ELA.

My comment was that ELA appeared to have stayed closer to the JT-5 configuration than their competitors.

[Dean_Dolph]

....... This demands accurate scales as well as an accurate clinometer since the angles are small. Ordinary bathroom scales aren’t good enough but commercial clinometers such as the “Smart Level” are fine.

I have a spreadsheet that performs the calculations if anyone would like a copy.Chuck, I also would like a copy of your spreadsheet.

I think I had it at one time but this was before my computer was a little more organized. That means I can’t find it!

I’m curious as to how accurate you think the scales should be since you say ‘ordinary’ bath scales aren’t good enough. It seems to me that the bath digital scales that indicate to 0.2 (3+oz.) of a pound and probably measure considerably closer than that, can’t be any worse than the double hang test and picture method. Using a picture of a double hang test seems to be crude by comparison and provides several places for error. And the main one is human! Taking an accurate picture, judging the prop thrust line and then using a drawn line to determine where the Cg is what I’m questioning.

I’m not sure how much effort is required to determine this but I wonder just how much effect 3 ounces of error has on Cg calcs if the attempt is just to get within the 4 inch (+/-2”) Cg box. I recognize that in the worse case scenario, the errors could be cumulative and add up on the wrong side but hopefully the probability is that they would cancel out.

I’ve never performed either one of these tests but just looking at what is required for a double hang test makes me favor using scales and an inclinator. If digital scales, that have had a full scale calibration plot created, were used then an interpolation should provide better accuracy and precision. And I would think that the results would be satisfactory; especially since true CLT is impossible to attain for all flight conditions. The flight conditions meaning a changing fuel load and the fact that pilot and clothing weight and distribution may change from flight to flight. I mention this because I don’t recall the pilot being brought into the equation on stability. This has always seemed strange to me, especially when talking about ultralight machines, since the AUW and not just the flying machines weight is going to be the determining factor on stability and performance.

[C. Beaty]

Send your E-mail, Dean, and I’ll get a spread sheet oozing down the wire in your direction (my rural telephone line doesn’t squirt, it oozes).

The main error from either weighing or photographing is the acute angle between the two positions. If the angles could be at 90º, there wouldn’t be much of a problem.

cabeaty@att.net

[StanFoster]

I have always wanted to do a double hangtest this following way ....maybe its been mentioned before...but probably not with use of a laser level.


I would hang test from the teeter bolt....and set up my laser beam so as it shoots a vertical red line going right through the teeter bolt. The vertical line could be marked on some posterboard taped to the mast.


I would then place the real wheels on an elevated platform that is high enough to allow the gyro to be tipped to its balance point on the mains.

With the gyro just sitting very nose high right at this balance point...the laser level could then project a vertical red line right through the center of main wheel axle. This line would then intersect the first line right at the cg of the gyro.

This of course is another slightly different way of double hanging it,,,,but I bet would be dead on accurate as the laser beam wouldnt have the parallax problem that using a plumb bob would have or trying to take a picture and "sighting" it in.


When I finished my SparrowHawk....GBA had me send them the weights taken from a scale under each main wheel and the nosewheel. I borrowed a set of very accurate scales that stock car racers use. Digital readouts and guaranteed within a few ounces of accurate. This didnt give me the CG of course..but was to replace hanging the gyro and measuring the keel or mast angle.


Stan

[C. Beaty]

I’ve seen laser levels that seem to go around corners advertised on TV, Stan. That might be the ticket but I have no idea how they work.

[StanFoster]

Chuck: First of all...your posts are super informative. I enjoy reading them until my eyes start glazing over. :der: Take that as a big compliment because it is.

Anyway....I use my rotary laser to project either a horizontal plane of red light or a vertical plane. This vertical plane of red light can effectively "visually cut the gyro right through the teeter bolt...on through the CG and on below.

Its just an electronic plumb bob.....except the light beam can easily go into all the nooks and crannies effectively splitting the gyro down its hang line. A physical item like a plumb bob has to be held outside of all obstructions and thats where the parallax error comes in.

I use my rotary laser in my stairshop mainly to project my 2d stair layout on the shop floor vertically so that I get a true 3d projection from it. It is the best investment I have ever made as far as controlling my stair build. It has to be dead on....or my stairs would never fit the cylinder on the jobsite they have to fit in.

Hey Chuck...I am going to look you up at Bensen Days and see if I cant soak up some sunrays and some IQ rays from you.:whoo:


Stan

Stan

[steveb]

.... The MT as far as I know has never had the v c of G tested as this isn't a requirement for sec T, which relies more on flight testing and this it obviously passed.


Brian, the POH for the UK MT-03 comes with a chart which shows the poistion of the C of G at various pilot / passenger / fuel weight combinations.

[C. Beaty]

How do those lasers that project a plane of light work, Stan? Is it a fan beam or is there a vibrating mirror that scans a single spot?

Whatever the case, that would be the ticket. Adjust the vertical beam to light up the suspension point of the hang rope and hang the gyro at two different angles.

That would eliminate errors from scales and landing gear extension. You wouldn’t need a clinometer. The greater the angle between the two suspensions, the smaller the error.

[bpearson]

I stand corrected Steve. What does POH stand for ?

My point was that comparing the ELA and MT when refering to vertical c of g / thrustline by looking at photos is pretty meaningless because of different blade weights etc. Saying these are more likely to be clt compared to the Magni (the only other clone of the JT-5) cannot be judged by just looking and guessing.

I would rather the test of stabilty be in the air, although it seems the American tests have flaws that render them inadequate.

[Walter]

POH stands for Pilots Operating Handbook.
It would be good to have a lookup table for all the abreviations you guys use, since it is difficult (e.g., CLT) for newcomers like me.

Walter

[StanFoster]

Chuck: My rotary laser has a laser beam on a rotating head. You can either turn that head 360 degrees by hand...or make it rotate by itself and it then projects what appears to be a red plane of light.

My laser is about the sixe of a rubiks cube puzzle.

I have an idea Chuck. Why dont I bring it down to Bensen Days...and we could do some double hang tests with a few gyros.....maybe one NCLT and maybe a low rider Air Command with a HTL. This could be a very easy demo and all it would take is the hoist they had down there last year and some posterboard to tape to the mast to trace the laser beams line. Two hangs..and voala....the intersection is the CG. :)

Stan

[steveb]

Brian

Someone beat me to it on POH!

I should have finished my post " .... and you can take a look next time we meet up - it's interesting stuff and supports your position that you can't tell what's going on by just looking."

Looks can be very deceptive. For example, the VPM / Magni has a heavy rotor, the MT-03 has a light one - but you can't tell that from a picture. The position of the VCG of the MT-03 varies according to the weights of the occupants and the fuel load, and I'd hazard a guess that the same is true for other aircraft with similar configurations.

[C. Beaty]

Sure, Stan. Bring your laser and we’ll work out something.

[StanFoster]

Chuck: This could turn into a mini event down there .....:first:


Stan

[gyrogreg]

POH stands for Pilots Operating Handbook.
It would be good to have a lookup table for all the abreviations you guys use, since it is difficult (e.g., CLT) for newcomers like me. Walter

Check out the Glossary of Gyro Terms (http://www.pra.org/index.php?module=article&view=18) on the PRA website.