Working on Brakes

[Sv.grainne]

I'm on the third iteration of brakes on my Genesis. Before Bensen Days I spoke with Denis and asked him if he could retrofit his brakes to fit the original axle struts on my machine. He said yes and we agreed to wait till he returned from the shows to get started.

I mailed my axles up about a week and a half ago and then last Tuesday I got an email from Denis with several photos of the original struts modified for the new smaller axle spindles that are compatible with his braking system. Denis shipped the modified struts and additional parts to me on Friday and I got them yesterday.

Parts are already assembled and I've precharged the brake lines and calipers with fluid.



Modifications required the addition of a new master cylinder and wheels and tires. I'm going to start the swap out tomorrow. The calipers, rotors and pads are way more substantial that the Mountain Bike modifications that I had incorporated into version 2 of my brakes.

I'm hoping that this modification coupled to an idled down engine that I can get more than 4 - 5 days on a set of pads.

 

[Resasi]

Be very surprised if you do not find it an improvement on what you are presently experiencing Bobby.

 

[Sv.grainne]

Be very surprised if you do not find it an improvement on what you are presently experiencing Bobby.

Version 2 added larger 4 piston calipers and pads which helped but wear issue still. I'm looking forward to version 3. Pads nearly twice the size, double the thickness of current, floating rotors so no more rotor alignment, rotors also substantially thicker, maybe 3-4 times.

I was worried about tires, no issue, wider but overall profile within a qtr inch.

 

[Abid]

Why are you on 3rd iteration of brakes on a gyroplane you got just a year or so ago?
What was wrong with Genesis brakes?

 

[Sv.grainne]

Abid: Severe pad wear and holding power at prerotation on first set. Modified with larger wheel cylinders, mtb pads, brake splitter. Much better but pad wear still excessive.
Will let you know how this modification works out. Engine idle set at 1500 RPM, tires 20 psi, prop pitch correctly set.

 

[AviomaniaTexas]

Why are you on 3rd iteration of brakes on a gyroplane you got just a year or so ago?
What was wrong with Genesis brakes?

Abid, nothing really wrong with them other than Bobby having very long distances to taxi with his 912UL pushing him too fast at idle. For future orders, I will give customers the option to order the heavy duty brakes we use on the Genesis Duo for their single place machines.

 

[Resasi]

My prediction based on experience of Denis's brakes... better hold and less wear. I have had experience of various types of brakes and Denis's and black Max seemed to me to be the best.

Obviously your lower engine idle will mean less wear during taxi time. Correct prop pitch should give you around 5800 WOT.

Local conditions, taxi distance, and stage in training obviously effects brake wear.

Denis's brakes hold well as I engage the pre-rotator and nudge up the power, but I am not really looking for more than about 180rrpm at this stage.

Later in testing for max short field performance I will possibly be looking for a bit more, but as Chris (Churz) found at higher RRPM's on brake release he would see an initial drop before it picked up again.

 

[Sv.grainne]

Thanks Leigh. I flew several days ago to test WOT and was 5700rpm straight and level so not going to mess with prop. I start prerotation and at 120 bring the stick back. Continue prerotation to 160 then release prerotator and wheel brakes and start takeoff roll making sure that RRPM is increasing.

Taxi distance is my issue. I leave the hangar and have a sloping downhill run to the main taxiway of about 1500' where I have a 90 degree left then 90 degree right turn then a flat down wind run of about 2500' to 90 degree left to hold line.

Normal conditions less than 10kt wind.

My current brakes are quad cylinder mountain bike calipers with heavy duty pads. Pads are about $40 per wheel and having to replace every 5-6 trips out a non starter.

I considered going with Aviomania two place brakes but with shipping costs and mfg lead time a factor opted for GyroTechnic parts.

A real plus was the one week turn around and the quality of the results is very impressive.

 

[Resasi]

I flew several days ago to test WOT and was 5700rpm straight and level so not going to mess with prop.

Sound good, the choice is always a balancing act. The 912 ULS as I understand it produces best torque at 5000 rpm provided the engine is set for a static 5800 rpm.

After 5000 rpm the more throttle you give the lower the torque, but the higher the HP. Without a constant speed prop the balance between climb, cruise and fuel economy occurs.

With prop pitch set to see 5200 WOT in level flight you loose torque and climb, then have to give it a bit more throttle which uses more fuel to get speed or HP. The engine is overloaded and in the long run can be damaging.

Setting the prop to get 5500 WOT, can better achieve a more desired torque with the engine less loaded. Speed increases and one can then throttle back and cruise at 5100 rpm using a lower fuel burn.

Set the prop to get a static 5700-5800 rpm WOT and one will get more HP and good torque… but… loses a little cruise speed and fuel economy trying to keep the cruise speed up.

Too much WOT or too little, uses more fuel with loss of climb or cruise performance depending on which way you pitched it. Always a balancing act, climb, cruise and fuel use along with where you live, alt above msl…and, where you most run your flights.

This change to Denis's brakes I think will give you a big improvement

 

[Georgi]

Sound good, the choice is always a balancing act. The 912 ULS as I understand it produces best torque at 5000 rpm provided the engine is set for a static 5800 rpm.

After 5000 rpm the more throttle you give the lower the torque, but the higher the HP. Without a constant speed prop the balance between climb, cruise and fuel economy occurs.

With prop pitch set to see 5200 WOT in level flight you loose torque and climb, then have to give it a bit more throttle which uses more fuel to get speed or HP. The engine is overloaded and in the long run can be damaging.

Setting the prop to get 5500 WOT, can better achieve a more desired torque with the engine less loaded. Speed increases and one can then throttle back and cruise at 5100 rpm using a lower fuel burn.

Set the prop to get a static 5700-5800 rpm WOT and one will get more HP and good torque… but… loses a little cruise speed and fuel economy trying to keep the cruise speed up.

Too much WOT or too little, uses more fuel with loss of climb or cruise performance depending on which way you pitched it. Always a balancing act, climb, cruise and fuel use along with where you live, alt above msl…and, where you most run your flights.

This change to Denis's brakes I think will give you a big improvement

Does anybody make PSRU clutches ?

 

[Aviomania]

for me these brakes are too heavy for the single seat quality (light and nimble)... but for your case Bobby they should be OK.....

Almost the same weight if we were using our 2 seat brakes on your single seat right from the start....

Personally i prefer to save that 2-3 lbs on weight... on the other hand i do not have to taxi long distances, so my pads last 2-3 years before i need to change them.

The thin light disks and pads ware out quickly if you overheat them..... the thicker pads and disks you are using now should help keep the temps down for your taxi needs.

The downside is that you will not be able to use the wheel pants now..... maybe our bigger ones... but not the ones provided.

 

[Resasi]

for me these brakes are too heavy for the single seat quality (light and nimble)

Personally i prefer to save that 2-3 lbs on weight.

Just checking with Denis on what a pair of GyroTechnic brakes will weigh.

You actually were pretty accurate.

Just got this from Denis.

"I just weighed calipers, rotors and hubs with bearings. (no axle)

3.01 pounds"

With both Bobby and I with 912's, and with 100HP on a single I personally am very happy to have good brakes.

 

[Sv.grainne]

Thanks for the comment Nicolas, appreciate.

 

[Aviomania]

Just checking with Denis on what a pair of GyroTechnic brakes will weigh.

You actually were pretty accurate.

Just got this from Denis.

"I just weighed calipers, rotors and hubs with bearings. (no axle)

3.01 pounds"

With both Bobby and I with 912's, and with 100HP on a single I personally am very happy to have good brakes.

Our 2 seat brakes that can be used on the single seat are 3.1 lbs ... and they fit with the wheel pants as well.

So now that we know that some people have to taxi for long distances we can be offering them as an option for the 912 engines.

582 do not need this system because the taxi at idle is not fast.

 

[Sv.grainne]

Once I have everything finished I'll post weight differences between what I have and what I end up with. The new wheels/tires are heavier than my originals. Understand about wheel pants, may try to add at a later date.

 

[Tyger]

I flew several days ago to test WOT and was 5700rpm straight and level so not going to mess with prop.

I am curious what your engine rpm is at WOT on climb out. I think if you only get to 5700 at WOT, straight and level, you might be too coarsely pitched. Which means (among other things) that you will be getting pushed forward too much when at taxi/idle.
When I first flew my machine, my 912ULS never got close to 5800 during climb out at WOT. It was also a bit difficult to gain altitude when fully loaded (600 lbs), depending on the temps, etc. So I repitched my prop finer, and now I get a lot less "push" at idle/taxi, and much better climbing ability, at the higher revs.
The main downside to the finer pitch is I can no longer go to WOT while straight/level because that now overspeeds the engine, and my max airspeed is only around 105 mph now as a result (used to get 115 no problem).

 

[Sv.grainne]

My test was 5700 straight and level

 

[Tyger]

I know, you said that, but I was asking what your revs are climbing out after takeoff, NOT straight and level. That's when you want the most power (i.e. highest revs) in my opinion. If you cannot get near the 5800 limit straight-and-level, you are almost surely nowhere near it when climbing out, which I think is an indication that your prop is pitched too coarsely, and this is reflected in your brake issues.

 

[Sv.grainne]

Misunderstood, I can get 5400

 

[Tyger]

Ya, that's WAY too low. You need finer pitch. It will be much easier on your brakes.