Autogyro idea

It is always easier to fit a cabin on an existing frame than the contrary.
A heavy gyro with enough power is a good traveling machine.
You can have a pilon hard coupled with the fuselage and then a pivot joint for the mast, with vibration dampener on it.
Size an height of the disc will give you the room left for tail and its volume.
Two hundred hp will be suficient but with reduction, direct drive is not a good idea for a machine like that. As it is not a good idea put a Ferrari engine on a VW beetle.
Have fun, work, more fun, fly and still . . .have fun!
Heron
 
It is always easier to fit a cabin on an existing frame than the contrary.
A heavy gyro with enough power is a good traveling machine.
You can have a pilon hard coupled with the fuselage and then a pivot joint for the mast, with vibration dampener on it.
Size an height of the disc will give you the room left for tail and its volume.
Two hundred hp will be suficient but with reduction, direct drive is not a good idea for a machine like that. As it is not a good idea put a Ferrari engine on a VW beetle.
Have fun, work, more fun, fly and still . . .have fun!
Heron

Obrigado Heron. I think you would be correct. It is in fact my goal to build a traveling machine with some comfort, range and no wind buffeting. I would like to have a short mast to reduce drag but that might not be possible as I move forward I will have to consult an engineer. So you suggest reduction ? My concern is the additional weight.
 
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Direct drive is not a good idea?

Direct drive is not a good idea?

Two hundred hp will be suficient but with reduction, direct drive is not a good idea for a machine like that.

Heron

Why is direct drive not a good idea for a machine like that Heron?

Thank you, Vance
 
Weight and track

Weight and track

Hello Barron,

The Predator weighs 800 pounds dry. Not unusual for a cross-country two place machine. There are some heaver and some lighter.

With two big people and full fuel it weighs around 1,400 pounds.

In my opinion that is not the limit of the rotor systems that is available from Sport Copter.

The engine and propeller weigh around 300 pounds and the rotor weighs close to 100 pounds.

That suggests to me that the rest of the aircraft weighs 400 pounds.

In my opinion a well designed composite aircraft can be lighter than a metal airframe with a composite fairing.

It is my understanding that Burt Rutan is weight conscious in all his designs and that particular design is focused on light weight and ease of construction.

If your airframe, body and landing gear weigh 175 pounds that leaves 225 pounds for the empennage, keel, rotor pylon and rotor control system for it to weigh the same as the Predator.

That seems doable.

As to your landing gear track; the Predator has around a seven foot track.

It is nice for landing in gusting winds.

Mariah Gale will be slightly narrower.

Five and a half feet might be a little narrow but not unheard of on a two place gyroplane.

Thank you, Vance
 
Reduction drive is used the match efficient engine rpm with efficient propeller rpm. Auto engines typically are higher revving engines (compared to certified aviation engines) and if used in direct drive will push propeller rpm to inefficient levels.

Also, keep in mind that you are starting with an existing fuselage and the firewall has limits as to how large an engine that can be attach to it.

What you are attempting will require extensive structural analysis to produce a safe aircraft so any engineer will need to be willing to devote many hours of work, and this is in addition to knowing how to arrive at a proper gyroplane configuration.

.
 
Sorry Vance, I was thinking auto conversion . . .a good aircraft engine will need no reduction.
The mast height will be dictated by a few things: prop size and centering, disc size, tail will be fitted after those measures are achieved. We are talking big here!
I have learned that adapting is way harder, had an Air Command and gave up on transforming it to CLT. Its an entire new ship.
Heron
 
I could be wrong, but as I understand it the Subaru motor produces its HP (210-265) at 3000 to 3800 RPM. This is why I was thinking direct drive, however reduction may be needed. Many people in another Rutan design use the Subaru direct drive as well ( Quickie Q200 ) all be it in tractor configuration. I believe the dry weight of the standard O-235 in a long Ez weighs about 255 lbs dry, where as the Subaru EJ255 is about 250 as well. However people are putting the Chevy and Ford V8's in the long EZ so I don't think there is much to worry about except proper cooling. I understand we are talking fixed wing Vs Rotor wing.

http://pursuitofflight.com/longezv8.html


With respects to the landing gear, I think wider will be better. I have studied the plans that allow the owner to install retractable gear on the long Ez and that puts the gear out pretty good. Which leads me to considering strakes for the wider stance and as suggested earlier for fuel.

http://www.infinityaerospace.com/Theeringer.jpg
 
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Basic Shape
 

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keeping it simple.

keeping it simple.

Hello Barron,

I like your doodle.

I feel you will need an empennage as large and as far back as practical to have her fly well. In my opinion groplanes land at very low speeds and a large vertical stabilizer volume and rudder volume are helpful as the speed goes down.

A lot of horizontal stabilizer volume is helpful to manage pitch excursions.

A rotor mast in the proper place would also be good.

In my opinion the easiest thing to manage for your project is to bolt on a 160 or 180 horsepower Lycoming. Engine mounts and cowls are available and that means you don’t have to mange cooling or worrying about how you stress the airframe. You don’t have to mess with engine conversions, radiators and re-drives.

My 160 horsepower Lycoming weighs around 280 pounds ready to fly and actually makes 160 horsepower at 2,700 rpm. A parallel valve IO-360 makes 180 horsepower at 2,700 rpm and weighs about the same.

I feel your numbers are a little off on the Subaru engine. Any that I have flown spend a lot of time on the far side of 5,000 rpm and weigh well on the far side of 300lbs ready to fly.

Thank you, Vance
 
Hello Barron,

I like your doodle.

I feel you will need an empennage as large and as far back as practical to have her fly well. In my opinion groplanes land at very low speeds and a large vertical stabilizer volume and rudder volume are helpful as the speed goes down.

A lot of horizontal stabilizer volume is helpful to manage pitch excursions.

A rotor mast in the proper place would also be good.

In my opinion the easiest thing to manage for your project is to bolt on a 160 or 180 horsepower Lycoming. Engine mounts and cowls are available and that means you don’t have to mange cooling or worrying about how you stress the airframe. You don’t have to mess with engine conversions, radiators and re-drives.

My 160 horsepower Lycoming weighs around 280 pounds ready to fly and actually makes 160 horsepower at 2,700 rpm. A parallel valve IO-360 makes 180 horsepower at 2,700 rpm and weighs about the same.

I feel your numbers are a little off on the Subaru engine. Any that I have flown spend a lot of time on the far side of 5,000 rpm and weigh well on the far side of 300lbs ready to fly.

Thank you, Vance

Thanks, I grabbed off of the internet and started hacking with Photoshop. Perhaps I am off with the numbers on the Subaru. However the point I think I am or was trying to make was I would hate to get it together and discover that it is under powered. For me THAT would be a waste of money. Sure, It would be much easier to throw an aircraft engine on it but at the same time when it come to TBO time, the costs involved seem to be very unsettling. Which is why I prefer an auto conversion. The parts are available everywhere. But I do understand your point clearly.
 
Hi Barron

This is really getting interesting, in your post #42 you ask about a carbon fiber mast grafted to the fuselage. The reason I mention some post back about a 4 post pylon shock mounted to the fuselage at reinforced points was I am thinking about some of the comments that have been discussed on other threads regarding vibration on both gyros and heliocopters. Here are some of the benifits of a 4 post pylon shock mounted at the base, 1. total elimination of high freq vibration transmission between the pylon and fuselage 2. major dampening of low freq pulses from rotor so the fuselage does not get so much stress from the rotor, finallly 4 post pylon is not hard to cover with a streamline fairing and it will give you a lot of room for various ideas for pre-rotor systems that could go inside the pylon. Vance is right about the simplicity of a aircraft engine installation but then I am always looking for as experiment to do (I am building a tractor) and I believe a Liquid cooled engine will be easier to achieve good cooling with in a pusher set up. My suggestion of a V6 was because of other experiments that have done well in fixed wing and they make for a nice compact installlation.

Sometime back there was a nice right up in Sport Aviation about a V6, I don't know if it was a Toyota or a Nissian.

Tony
 
Hello Tony.

Yes it it rather interesting conversation. About the mast, my thought was to use carbon fiber if it would save weight at this position. Couldn't you manage the vibration by using vibration dampening at the top to eliminate that getting to the fuselage. I think a single point mast would provide less drag. I also would hate to invade the rear seat or both seat with structure and aerodynamics to clean it up. We might not be able to see the sky. But then again a pre-rotor would be a very nice feature. A decent V6 would be an option, was the direct or geared ??
 
Barron

Some time ago , I bought 3 editions of "alternative Engines", a publication by EAA. If I can find those books, one of them had a article about a guy that was building a scale P-38 and using V-6 engine, I think these were belt drive though and I would for sure go gear drive. More later .

Tony
 
Barron

I found two of the books, and the one with the scale P-38 used small V-8 engines, so I was wrong on it. The V-6 conversions in the books are all Ford or Chevy so I can't think where I saw the Japanese V-6 conversions at the moment.

Tony
 
Barron

You might send Neil Hintz at Autoflight in NZ a e-mail and ask about his H6 gear box, he made it specifically for the Subaru H6 6 cylinder engine. The H6 now comes in 3.0 and 3.6 L and well over 200 hp. He could probably tell you about the success of the engine and how well it has turned out and who has used it. Check his web site for pictures of the H6 and his gear box.

Tony
 
Outstanding idea!! Great look if you can get cg right with hang test
 
Barron

You might send Neil Hintz at Autoflight in NZ a e-mail and ask about his H6 gear box, he made it specifically for the Subaru H6 6 cylinder engine. The H6 now comes in 3.0 and 3.6 L and well over 200 hp. He could probably tell you about the success of the engine and how well it has turned out and who has used it. Check his web site for pictures of the H6 and his gear box.

Tony

Found his site will give him a call. Thanks
 
Barron,

I don't mean to throw a damper on your enthusiasm or this project. However it is clear to me from what is being said that you are way over your head on this and don't have a clue how much you don't know yet. My advise is to take it slow and before you start off on any particular direction, that you do some extensive research so that you understand the alternatives better.

First time builders are usually way better served by simply building a kit that someone else has designed because they are a lot less likely to make expensive and dangerous mistakes. If a person has the skills already and wants to build something from plans, that takes a lot more work but would be the next level. Then going on to design and build from scratch your own unique aircraft would be the highest level of risk and most work. I can't help but feel you are taking on a superbowl sized challenge without the training or knowledge or experience that is normally required for success in an endeavor this size. While I hope you are sucessful and would love to see you complete a great new machine that may go on to change and evolve sport rotorcraft someday, I think the odds against that happening are large.

I simply am tryijng to get you to open your eyes and gain a better understanding of what you are attempting to accomplish. There are many good books available to help you understand the principals involved and there are many experienced and knowledgeable people who can mentor and help you through this process. I pray that you will take it slow and learn how much you have to learn before you start down a road that will end up costing you more than you have any idea right now. And I really do wish you "all the best" in this endeavor!
 
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