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Prerotator devices

Old 04-16-2007, 04:40 PM
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Default Prerotator devices

Hi Gang , Have there been any new developments in prerotators that you would like to share ?? How about you PT Gyro pilots ?? Any devices using the factory rotor head ?? I think most of you would agree that prerotating is the way to go. Astonishing liftoffs in a few feet, as opposed to many yards of taxiing, or hand-launching. Very exciting. Perhaps the parts from Begi or GT17 could be adapted to direct-control gyros...... certainly should be adapted to fixed-rotor gyros...... How about a small electric motor with freewheel/sprag clutch and its own battery (for gas powered models), microswitch-activated by pushing the stick fully forward (full down elevator) ?? And, at the risk of sounding somewhat ridiculous, why not try a wind-up mechanism adapted from a kids' toy ??? LOL !!!! My Kalt Robin 40 gyro had a prerotator PTO from one wheel. This led to excess drag on that wheel, and a problematic turning to one side while taxiing. Maybe if both rear wheels were connected, this problem could have been allieviated. Whatcha working on, guys ??? Happy Flying !!! Charlie Anderson
Old 04-16-2007, 05:17 PM
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Default RE: Prerotator devices

We at FlyingBalsa have not been actively pursuing a pre-rotator because we have never really needed one. But with all the interest in pre-rotators maybe it's time to 'come up with something'. The only thing with me is, I try real hard to keep things very simple but functional. Our particular head design doesn't lend itself well to a pre-rotator (keeping simple in mind). I'm sure not changing the head design so I guess we will have to get the 'ole brain cells working on this. First problem: where am I going to find time for THIS?

Mark
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Old 04-16-2007, 06:10 PM
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Default RE: Prerotator devices

Hello Mark,

I can't agree with you more. A good spin of the rotor and taxi into the wind is all that is needed to get airborn. We could sit around and dream up some method to prespin our rotors so that we could be like Mickey but it is simply not needed or required with the AeroBalsa blades in use today, I've never had any trouble getting off the ground. If we wanted a helicopter we could go out and get one at any hobby store. Since these are autogyros and are more fun than any helicopter and fly much better, why should we try to be like a helicopter. I've watched many, many helicopters at model flying fields and for the most part unless the pilot is a real pro all they do is hover, hover, hover then wind up in a ball of twisted parts that are very expensive to replace.
The PT series you and John provide all lift off the ground with very little roll so don't mess around by adding more weight by trying to be like Mickey.

See you in September,

Joel
Old 04-16-2007, 06:36 PM
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Default RE: Prerotator devices

Hi,

If you want to install a pre-rotator on the PTGyro, it's not difficult, thanks to Mickey's engineering. First, the PTGyro uses about a 2.4 mm rotor shaft and the PT 25 uses a 3.3 mm or .125". The GW/EPSC gear box will will accomadate the different size shafts. The standard is 3 mm. Then you mount the GW/LPS gearbox for the pre-rotator. You don't have to use the GWS brushed motor. By accident I discovered that the Feigao 128425 brushless motor fits the GWS gearbox perfectly and use a little 10 amp speed controller.

The GW/EPSC will mount on a .4" square tube, so now you have the holder with bearing and your pre-rotator. Now just remove the original bearings from the rotor head, install a bushing or whatever and pin the shaft to the rotor hub.

I have attached a picture, and also you will need the one-way bearing, available from Boca, any size that you need.

Phil
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Old 04-16-2007, 06:53 PM
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Default RE: Prerotator devices

Hi,

Forgot to include the close-up picture all assembled with the Feigao motor.

Phil
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Old 04-16-2007, 07:00 PM
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Default RE: Prerotator devices

Hey Phil, You're the man !!! Thanx for sharing the nice prerotator arrangement. Can you give me a ballpark figure for the complete unit, including the replacement spin-up motor and speed control, minus rotor head ?? Thanx !!! Charlie Anderson
Old 04-16-2007, 07:14 PM
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Default RE: Prerotator devices

Hi Gang, By the way, this is not about "being like Mickey". It is like being about Juan De La Cierva and Harold Pitcairn, smart fellows who realized back in the 1920's that a prerotator brings the maximum potential out of the autogyro. I do not wish to fly a helicopter, but to simply fly the best gyroplane possible for the buck. Gyros should not need wind or taxiing for spin-up, as shown by Mr. Nowell's (and Mr. Ploof's) clever designs. There is clearly a better way, and it is great that fellow modelers are sharing their ideas with all of us. The choice to use the new technology ultimately rests with you. I do not knock hand launching or taxiing. I also appreciate the hard work and long hours it takes to develop new designs. Thanx to all for sharing these new innovations....... Charlie Anderson
Old 04-16-2007, 08:17 PM
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Default RE: Prerotator devices

Hi Charlie,

GW/LPS pre-rotor gear box and brushed motor $13
GW/EPSC main gear box, bearings and shaft, approx $10
Pixie 7 am speed controller $29.00
Boca one-way bearing approx $9.00

If you want to use the Feigao brushless motor instead of the GWS $33
10 amp brushless speed controller $20

If you use the aluminum 10 mm (.4") square tubing for your pylon the GW/EPSC will mount right on top and this will reduce the weight and actually lighter than the plywood pylon.
Another suggestion, buy the GWS Slowstick for about $32 and you will have the square tubing and the nice little plastic servo brackets to mount on the square tubing which control the rotor head. Really gets the weight down and the Slowstick includes the gearbox and bearings.

Phil
Old 04-16-2007, 08:38 PM
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Default RE: Prerotator devices

Hi,

Another plus for the pre-rotor, it allows you to really balance and check the blade tracking right on the bench. The Brushless Feigao will allow you to really spin those blades but you have to be a little careful with the GWS.

Phil
Old 04-16-2007, 08:45 PM
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Default RE: Prerotator devices

Excellent , Thanx Phil, Sounds like you have it down to a science !!! I appreciate your help. Charlie
Old 04-16-2007, 08:59 PM
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Default RE: Prerotator devices


ORIGINAL: JoelW

Since these are autogyros and are more fun than any helicopter and fly much better, why should we try to be like a helicopter. I've watched many, many helicopters at model flying fields and for the most part unless the pilot is a real pro all they do is hover, hover, hover then wind up in a ball of twisted parts that are very expensive to replace.
You are certainly entitled to your opinion. However I have 3 gyrocopters and 3 helicopters. They are all fun to fly, none especially more
fun than the other. If all the helicopter pilots do at your field is hover and crash then you have a bad sample of helicopter flyers.
The ones I fly with, including myself, do rolls, loops, fly inverted and backwards. The neat little blade coax helicopter is really easy
to fly and most people can master it in a short time. I don't think there is a need to bash on helicopters just because you like autogyros.
Old 04-16-2007, 09:03 PM
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Default RE: Prerotator devices


ORIGINAL: ottogiro58

Hey Phil, You're the man !!! Thanx for sharing the nice prerotator arrangement. Can you give me a ballpark figure for the complete unit, including the replacement spin-up motor and speed control, minus rotor head ?? Thanx !!! Charlie Anderson
I have kits that are $22, they include the bearing, the plywood mounts, the gear and hardware.
You supply a motor ($13) and speed control (~ $25) and a GWS speed 400 gearbox ($1.25)

Old 04-16-2007, 09:42 PM
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Default RE: Prerotator devices

Since being "like Mickey" seems to be part of this thread here's Mickey's opinion.

1) PT gyros are nice machines. I have no beef with FlyingBalsa.

2) The tilting head on the PT has the advantage that you can tilt the rotor head
back while taxiing. This greatly aids spinup.

2) My swashplate controlled rigid head doesn't tilt so it is more difficult to spin up
by taxiing. The pre-rotator makes up for this.

3) You still have to hand spin the PT, according to Joel and all my observations. This
is no big deal but does deny you the ability to taxi downwind to the end of the runway
turn around and takeoff. The pre-rotator allows this, just as Phil has mentioned. This
improves the respect my gyrocopters get at the field and at airshows. Besides, it's fun.
At my field they get all hinky if you walk out into the runway.

4) I developed the pre-rotator for BEGi which is a tall, short pusher. It can be challenging
to takeoff in a crosswind or dead calm. The pre-rotator makes this model fun to takeoff in
any situation.

5) With pre-rotation I can mix it up with the other models on the field and takeoff down
the pavement without having to go directly into the wind. Not all of us have a big field all
to ourselves. The wind is always cross at my field and the runway isn't that wide.

6) With pre-rotation I can fly indoors in a basketball court in dead calm.

7) In completely dead calm conditions I can clear a 6 foot obstacle 10 feet in front
of the model. (there is video of this on my website) I can takeoff downwind with no problem.
I can takeoff from a picnic table on a dead calm day. I don't care how fast your rotor spins up while taxiing it
won't do these things without some kind of pre-spin. My pre-rotator brings the rotor up to
essentially flight rpm.

8) Charlie has a point. The peak of autogyro development was with collective pitch,
pre-spin and jump takeoff. There is a commercial gyrocopter now in development with
jump takeoff with a video floating around. Don't blame me for pre-spin. I didn't invent it
or the need for it. The full sized guys did. I just made it work reliably on my models.


9) Bensen developed pre-spin on his gyrocopters because it provided balance. The aircraft
could takeoff anywhere it could land. Before pre-spin he could land in places that he couldn't
take off from. This is very clear in his book.
With pre-spin I can takeoff anywhere I can land. This does provide some
flexibility in where you fly.Most of my kits get sold with pre-rotators, so somebody else sees the need.

10) With pre-rotation I can run flatter pitch and fly slower than I can without it.

11) With pre-spin I can hand launch in a rough field with no wind and no running. Try that
without pre-spin.

Finally
I'm not advocating that you use pre-spin or don't or that you copy me to be "like Mickey" or not.
You guys can hash that out amongst yourselves. I have pre-spin because it works, I don't mind
it being more complicated and it provides performance that not having it can't match.
By all means if you don't think you need pre-spin, don't use it.
Phil is probably fired up about pre-spin because for two years in a row he's seen me at
Spring Hill, taxi out, spin up and takeoff when everyone else is grounded because of crosswind.
Like it or not the pre-spin lets you fly in more situations than without. That's why I like it.
Old 04-16-2007, 09:56 PM
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Default RE: Prerotator devices

Hello Mickey,

You sure seem to have a tender spot!! Why don't you and all your expertise come to Morris next September and show us how yours is better than ours.

See you in September!

Joel
Old 04-16-2007, 10:03 PM
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Default RE: Prerotator devices

Hi Mickey, Thanx for your input on this subject. Your experience is invaluable. Keep up the good work. Charlie Anderson
Old 04-16-2007, 10:23 PM
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Default RE: Prerotator devices

Hey guys,

I had a lot of gyro pilots who stopped by my booth at the Toldeo show say they would like to have pre-spin on their model. Even though it may not be required on some models, there are folks that would like to have it just to shorten up the ground roll.

What I see as the ultimate challenge in model autogyros is to develop a jump takeoff feature... as in a real vertical takeoff. Now THAT would be something to see!
Old 04-17-2007, 07:38 AM
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Default RE: Prerotator devices

Hi,

While Mickey was developing his gyros, I build a Wallis gyro which has the swashplate and pre-rotator and this was developed by Col. Ken Wallis back in the 70's. This is about a 10 lb. model and certainly needed the pre-rotator.

Also, did anybody see the Whopper Robbe Schluter that just sold on E-Bay for $430 with shipping? I wonder if it was anybody in this group that bought it.
Anyhow, it's a large tractor type, with swashplate and pre-rotator. I would guess about the same size as the Wallis.

This is the link to the E-Bay page if you are interested in seeing the pictures.

http://cgi.ebay.com/WHOPPER-ROBBE-SC...QQcmdZViewItem

Phil
Old 04-17-2007, 07:42 AM
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Default RE: Prerotator devices

Hi,

Maybe that link doesn't work, if not here are some pictures of the Whopper Robbe Schluter Gyro.

Phil
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Old 04-17-2007, 09:50 AM
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Default RE: Prerotator devices

hello Phil,

Sure is keen! I'm sure you'll bring it to Morris in September to show us how keen it is. I'd sure like to see how it flies better than our direct control machines!

Joel
Old 04-17-2007, 11:11 AM
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Default RE: Prerotator devices

Hi Joel,

I have two of the PTGyros and one PT25 and I think they are great. However, I also converted a Sig Senior Kadet and a 1/3 scale Cub to a single rotor gyros with the flapping blades and both were much more stable than any of the PT Gyros probably because they are bigger. I also have the RotorShape gyro and if you just want to flip around the sky it will do it better than any of the PT's, probably because it's smaller and better power to weight ratio.

So it all depends on what kind of flying you enjoy and for a beginner, getting the gyro in the air long enough to experience the controls is probably the most challenging and the pre-rotor certainly improves the odds.

Phil
Old 04-17-2007, 11:21 AM
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Default RE: Prerotator devices

Joel,
Let me make sure I understand how you feel:

You don't think we need pre-rotators at all.

Putting a pre-rotator on is trying to make the autogyro into a helicopter.

Autogyros are more fun than helicopters.

Anyone that is interested in a pre-rotator is somehow trying to be like Me
(instead of like for example : Cierva, Pitcairn, Kellet, Bensen, Brock, Rand, Wallis, Groen,
Robbe, Micromold, Kalt, Air Command, Charyair, Little Wing, Magni and
Carter Aviation which has jump takeoff as well as prespin)

You think I have a "tender spot" because you make something bad out of wanting
to be "like Mickey" and I step up to defend myself..

So i'm guessing that you want everyone to shun me like a leper so I'll wise up
and quit working on this foolish pre-rotator enabled, swashplate controlled heresy....

Please let me know what I did to personally offend you.
I'll gladly apologize.

mickey
Old 04-17-2007, 11:31 AM
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Default RE: Prerotator devices


ORIGINAL: AeroBalsa Mike
What I see as the ultimate challenge in model autogyros is to develop a jump takeoff feature... as in a real vertical takeoff. Now THAT would be something to see!
You will. Work in progress.
Old 04-17-2007, 01:28 PM
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Default RE: Prerotator devices

Hi,

Did a little flying today but not much. I was the only one at the field as the wind is really blowing. But I did try the PTGyro which has the Swashplate control and I removed the horz stab between flights. Considering the conditions, I couldn't really tell the difference before and after.

Joel, I have a challenge for you, remove the horz stab on your gyro and lets see how it flies. Actually it may be OK, not sure. However, I can say that orientation is more difficult without it.

Phil
Old 04-17-2007, 03:35 PM
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Default RE: Prerotator devices

I couldn't say for sure what would happen if the horizontal stab was removed from one of the PT family of gyros. I am fairly certain they can be quite a bit smaller on both the original 1/2a PT Gyro and the PT25 though. Those were both drawn up using the "that looks about right" method. The PT Profile stab was drawn up in a different manner. For those of you with sharp eyes will notice that each stab/elevator half is exactly the same as the fin/rudder shape but with a cutout for rudder travel. Still very unscientific but it is smaller percentage wise than the 1/2a and PT25 models. Goes back to my earlier statement about keeping it all simple. That's as simple as it gets with a CAD drawing to come up with a 'shape'! Would it fly with no stab? There's only one way to find out... Chop Chop
Mark
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Old 04-17-2007, 05:19 PM
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Default RE: Prerotator devices

Hello Phil and Mickey,

I won't roll in the mud with you two any more. It's obvious we have a different opinion that will not be changed. Perhaps the two of you will show up at one of our yearly Fly-ins and demonstrate your superior flying machines for all to see. Until then I'll have to keep my opinion.


They say you should never roll in the mud with a pig, because the pig likes it.


See you in September

Joel

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