Proper Airfoil for Horizontal Stab ? [Archive]

oldpilot

09-11-2004, 12:10 PM

Ron Black

09-11-2004, 02:00 PM

Greetings old pilot,
You probably will get a lot of help here on the forum.
I will help maybe a little.
If you were to down load a copy of the gyro bee plans from Ralph Taggart's site,
there is info on building The watson tail group.
Although this may not be the exact thing you are looking for, you may get some good ideas as airfoil shape etc. Ron

oldpilot

09-11-2004, 06:22 PM

Thanks Ron,

I think I posted this thread in the wrong spot on the FORUM but don't know how to move it to the Enclosed Two Place. So I guess people will see it??? (you did :-)

I will check out Taggart's site.

John_wilkinson

09-11-2004, 09:27 PM

Steve we lowered the thrust line by 6 inch on our RAF with good results plus a good stab sutch as Stan has.

KenSandyEggo

09-11-2004, 11:35 PM

Steve, are you buying a kit or an existing RAF? If a kit, why not just go for the Sparrowhawk? It costs slightly more, but you get way more than your money's worth over an RAF kit. If you're buying an existing gyro......never mind.

oldpilot

09-12-2004, 07:27 AM

John,

Do you have any photo's which show more (any) details on how you modified the CLT? The photo you posted doesn't show the tail section (underneath) very well due to the shadow. I would really like to see what you did to modify the tail boom but the distance of the photo doesn't allow it. It looks very professionally done however!

Old Pilot

oldpilot

09-12-2004, 07:59 AM

KenSandyEggo,

I am purchasing one that is already built.

I have been following the SparrowHawk since last year. I even went to Puyllap, Washington to the airfair and saw their partially constructed model (and sat in it). The only post I read on this FORUM of a completed one (not from an AAI dealer) said it had not lived up to the Mfg. claims on performance and seemed to be a heavy RAF2000. There is a noticeable (sp?) difference in interior headroom and width but the manufacture and testing on them has been so painfully slow I think one could argue that they are far from working the 'bugs' out. By my count there are only 2-3 completed SparrowHawks anywhere and all are in "testing" phase.

There has been a lot of 'hype' about the SparrowHawk but most of it comming from AAI to encourage sales. The real test of the SparrowHawk will come from members of this FORUM who begin to fly this Gyro. When a hundred or so of them have been flying a year or so in many different environments year around - then I think we all can draw a more rational ( and independent) opinion of the SparrowHawk.

Personally I like the SparrowHawk, but it is on the expensive side to purchase and out of the range of the average 'backyard' Gyro buyer - in my opinion. I will save my money and purchase a Talltail kit from them someday, if the price stays down and they are still in business.

Which brings me to the final point on the SparrowHawk, since you asked me about it. Groen Bros., the parent company has some enormous debt and their stock value has dropped over the past few years from several dollars per share to a current value of 18-25 cents per share! A lot of investors have lost their shirt and the insider trading looks like more selling of the stock than buying. No one is talking about that...these are all public records available on the internet. Even though I truely hope the SparrowHawk proves to be a success and an advancement in the Gyro field I worry that their optimism at AAI/Groen Bros. and the marketplace don't hit head-on in a train wreck!

Old Pilot

Kevin_Richey

09-12-2004, 09:01 AM

This is my first post so go easy on me, Please.

I am purchasing an RAF2000 GTX SE FI soon and will need to put a horizontal stab (HS) on it. There is some info on several manufactured HS's available on this FORUM and other places. However, I find no info on the type of airfoil being used (maybe a trade secret??).

I would like to add the AAI stability augmentation kit but cannot afford it at this time. I see that many of you are happily flying about with a variety of HS's. Since I would like to get flying I wanted to see what the "conventional wisdom" of this group is on which HS I should start with and if I build one what airfoil should I use?

I am a Private Pilot (ASEL) and flew a SportCopter many years ago (ultralight) that I assembled from a kit - so I have SOME experience but it was a long time ago. I plan on obtaining instruction and an add-on rating for Gyro, so no need for the customary cautions.

Hi Steve! Gary Kaminski flies his RAF 2000 out of Chehalem Valley airpark in Newberg and he has added a horizontal stab to his machine. You could ask him to view it to see what the airfoil shape looks like.

I'm one of the two fellas that came to your home back in '93 and bought your Rotor Lightning.

That is it in my avatar photo above! It is a shot someone took of me landing at Leo Boyer's grass strip in Gaston during one of our chapter meetings.

I thought you'd like to hear what happened to it over the next several years.

Dan (the other fella) bought it from you and taught two of the five guys who became joint owners of it to fly a gyro. Two backed out, one citing pressures from wifey since they had a couple of little children and the other admitted he was scared to leave the ground.

The third guy was rotary forum member Julie's dad, Dave Richardson. He and Dan couldn't get together on the same schedule for training, so he also didn't fly it.

I and the other guy (Jim Ginn) flew it a lot over the next year or so.

I had 75 hours in it and Jim over 100. Last I heard, the hour meter showed around 240, when Jim took it to Colorado. It had 22 on it when you sold it to us. It was hangared at the Estacada airport.

The gyro saw the scenery over the Columbia Gorge, Mt. Hood, the coast at both Siletz Bay airport and Tillamook airport, and much of the area between. It was flown to these locations, not trailered.

We did trailer it to the PRA chapter meetings at Scappoose.

I had four emergency landings in it, and Jim two. No damage on those six landings other than the plastic wheels (that helped make it an ultralight) developed cracks around the hub before we replaced them with aluminum ones. Anyone who is interested in reading about my four emergency landings and my foolish mistakes that led to three of them can read the past newsletters on the Chapter 73 website located at: www.pra73.net

Jim G. bought Dave and I out of our ownership shares. He lost his job of over 20 years as a maintenance man in one of the paper mills there at Willamette Falls in Oregon City, and with his severance package, moved to Colorado Springs to open up the first Papa Murphy's Pizza franchise there.

He told me that he couldn't get out of ground effect with the 503 dual carb (we added the second carb after we had been flying it around for awhile), even with some help from local Colorado guys in getting the carb jets changed for the altitude.

He trailered it back to Oregon, where it was sold to a friend of Leo Boyer who had liver (?) cancer and had lost his medical. He and Leo flew their respective gyros together around the Gaston area, where that other guy had a grass strip on his property.

This other guy (don't recall his name) succumbed to the cancer and his wife sold the gyro to someone in the Oregon City area, two or three years ago. Don't know of it's whereabout since then...

Kevin

oldpilot

09-12-2004, 12:48 PM

PW_Plack

09-12-2004, 01:41 PM

Steve,

I've heard some griping that Groen Brothers are better at raising capital than developing aircraft, but they appear convinced that the horrible statistical safety record of gyroplanes is part of their problem moving forward. According to their press releases, that is their reason for doing the SparrowHawk project, to provide a safer alternative to the RAF. If they succeed to raising the safety level within the sport, or even succeed in getting prospective buyers to understand why some gyroplane designs are unstable, they may pave the way for Hawk-IV sales.

As far as the design being proven, much of the SparrowHawk airframe looks very similar to the RAF. The cost is also about the same. Most builders have $30K-plus in their RAF's, and the SparrowHawk is a more complete kit.

Even if you're buying one already built, you might find Gary's builder's site useful. There are some parts on your machine you may want to upgrade for safety. Gary's site: http://home.att.net/~raf2000owners/home.htm

John_wilkinson

09-12-2004, 03:48 PM

Steve have a look at flying photos and click on New Zealand altered RAF

oldpilot

09-12-2004, 05:47 PM

Paul,

Good to hear from you!

I do not know how good Groen Bros. is at raising capital but their public record indicates that one of their major problems is SALES. They seem to have poured quite a bit of time and money into Research and Development (R/D) but can't get them sold. It just defies me, because they seem to have the right idea and highly qualified people working for them and running things??

I do feel that they are taking too long to get their product to the consumer and someone made a VERY poor decision to RAISE the price of their SparrowHawk from $27,300 to over $30,000.00 recently. AND I would like to know why they priced their RAF 2000 Stability Augmentation kit at ~$5,000.00 ?? I do not see any FIRE SALES or promotions or anything to stimulate SALES. I would think the more 'Birds' they have out there the more the demand will be - but what do I know...everyone's a critic.

However, to look at their Balance sheet you need to be sitting down. One must wonder how much longer the bleeding can last.

The one thing I can say they did to stimulate sales was to develop the Stability Augmentation kit (SAK) for the RAF 2000 - to begin the attempt to improve the Gyro safety record. That inturn should stimulate sales for their SparrowHawk and Defender (AND THE RAF 2000) - in theory. The problem is the SAK is too expensive and will not have the desired impact on Gyro safety stats until it is in wide use and for more Gyro models than the RAF 2000 (in my opinion as a consumer).

I believe the SparrowHawk is going to turn out to be a good 'Bird'. But I also believe it will be an oversized RAF 2000. Its larger cabin will create more DRAG AND WEIGHT...so they increased the horsepower. So now you burn more fuel, go approx. the same speeds and have more elbow room. Some people will want that some will not.

I do not think it is a more complete kit, by the time you spend ~ $31,000 to get a kit delivered to your door, you still need to assemble it and add NAV/COMM and Transponder at the minimum. So add ~ $3-4,000 minimum. THEN how many thousands of $$$ for a Gyro rating @ $135.00/hr dual??

My point is that NO ONE will do well in the two place enclosed Gyro market until they get their prices down to where the average Gyrohead can afford one.

Just so I don't get too much hate mail from GNBA and AAI I want to make it clear I LIKE your 'Bird' and hope it sets a new standard. However I think it is too expensive and is untested in the real world as of this writing.

I hope we can get together one of these days - I see you are VP of Chapter 73 - - Congrats!

oldpilot

oldpilot

09-12-2004, 06:16 PM

Kiwi John,

Thanks for directing me to the New Zealand modified RAF. Excellent photos! What airfoil was used for the Horizontal Stab?

Oldpilot

StanFoster

09-12-2004, 06:30 PM

Oldpilot: Its well known I love my RAF with my Parham stab. It handles very nice with the doors on,....I flew home over 80 miles today with lots of thermal activity and never once was uncomfortable. It was a real nice flight.

Good luck with your RAF and I assure you that you will be very pleased with it.

You can e-mail in private for more chit chat if you prefer. I would be happy to mention some names of high time RAF pilots that gave me the confidence to go buy one for myself.

Stan

oldpilot

09-12-2004, 06:44 PM

StanFoster,

Thanks for the info Stan. I appreciate knowing I can contact you for advice once in awhile.

Cordially,

Oldpilot

StanFoster

09-12-2004, 06:46 PM

Oldpilot: Gregg Gremminger took photo of our trio of RAF's today at the Shelbyville, Il. fly-in. Each of these RAF's has a stab..but each one is different.

Mine is the RAF in the front and has a Parham stab on it and it is works very nice.

The RAF in the background is Jeff Millburgs and he has a Kenny Janulewicz stab.

Dan Probst is piloting the nearest RAF and has the stab from New Zealand..I think its Paul Bruty's design....Am I correct Paul?

Anyway....they all fly nice and we all three get some serious hours in our logbooks and go places. :D

Stan

Kevin_Richey

09-12-2004, 06:50 PM

Kevin,

Wow, what a great reply! I never did know what 'really' happened to that UL Gyro. You brought back some good memories. Someone had told me years ago (can't remember who) that the gyro was crashed soon after I sold it and that is what I believed all these years.

It was ground looped a few months after you sold it. It was done by the guy (Todd) with the "wifey-says" problem. He had dual training with Jim Digaetano in his side by side Air Command in Las Vegas just prior to the incident. He had been soloed.

He was taxiing our gyro at Scappoose at one of the chapter meetings, going rather fast balancing on the mains. One of the wheels rose up higher and he became airborne a few feet high. Jim Vanek was the only other person to see what then occured, as he was flying by overhead.

Todd became crabbed, and he panicked, chopping the throttle. It came onto the wheels sideways. He said that he immediately knew that he should have added throttle and straightened his heading with the rudder pedals, then reducing power and settling onto the runway.

His only injury was a small cut on his hand from standing the gyro back up onto it's wheels. The fiberglass fairing had some splinters from the ground loop that bit his hand.

The gyro was down for a couple of months getting it's few bent parts replaced. Most of the wait was for receiving a new set of rotorblades and prop. The fairing was sanded a bit, and I think the control rods were replaced, along with part or all of the rotor head and rotorhead cheekplates. A new horizontal stab also. That welded airframe sustained very little damage.

Are you still out along the Willamette River there in Wilsonville?

r.coplen

09-12-2004, 07:18 PM

Hi Steve,

I would like to invite you to come fly in my AAI modified RAF and my SparrowHawk before you go to the trouble to buy RAF. I remember visiting with you at the NW Conference and would like to get you more information about the gyroplane industry as a whole to you. What you do affects all of us.

I know GBA has some debt and as an invester for over nine years I know that it is a normal situation for a company that is bringing new technology (In this case old technology that has be updated) to the market.

A major portion of dept is to the dealers such as myself. It is listed but won't be paid back untill we start selling Hawk IVs. The amount of debt is not high compared to other technology startups. (Like Eclipse or software startups) I have had purchase order requests for 34 Hawk IV's from law enforcement agencies ( to be operated under the public use law) in my dealership alone. That was over $36,000,000. They were to be funded by the Home Land Defense budgets. I believe they were left off because of the accident rate of gyros.

The issue about accident rates affecting our sales is real. From the 1920's through the 1950's the death per 100,000 hours in gyroplanes was the same as the rest of general aviation. From the beginning of the 1960's through 2002 the rate of deaths pre 100,000 hours in gyroplanes was 23 times that of other general aviation. It has now starting to drop. The British government said that the high rate was caused by the thrust of gyroplanes raising substantialy above the center of gravity, lack of substantial horizontal stab, and the lack of a formal training program for new pilots. The British have now banned any new gyroplanes that have the thrust more than 2 inches above the center of gravity, not enough horizontal stbility and have instituted a much more stringent training program for new pilots. They have demanded that the testing procedures prove stability. There goal is to get gyroplane accident rates in line with the rest of general avaition. (That should be our goal too. It sure is mine!!) You can find this report in the reported accidents on this forum. GBA set about the same program several years ago after we found such difficulty in getting issurance and getting aviation agencies to take our work in the gyroplane part of avaition seriously.

I have found it impossible to find issurance for training because of the high rate of accidents. We have instituded a intensive formal silibus for training developed by Terry Brant and it is the standard for all the AAI dealers.

Gyroplanes as a part of aviation will never be excepted by general aviation until we as a whole take the steps to get the accident rate on apar with the rest of general aviation.

Steve, you said AAI is prejudice about our product. I totally agree with you, but for a different reason. My success in making a living depends on you staying alive. I want you to fly our products because I know they will keep you safe. Untill you and the majority of the rest of the gyroplane industry take the steps to get the training that is necessay and buy and build centerline thrust aircraft, we won't get the recognition from the rest of the aviation community that we should have.

oldpilot

09-12-2004, 09:09 PM

Randy,

Good to hear from you...I figured it wouldn't be long before someone from AAI contacted me :D .

I have had several phone conversations with you and now this FORUM reply. In each case you have impressed me with your honesty and integrity and politeness (even when I brought up the subject of Groen Bros. Stock dropping in value).

I am likely going to take you up on your offer to visit your facility and fly both machines. At the very minimum I will need to find an instructor and I am sure you could make a recommendation in that area.

I am also interested in the training syllabus Terry has created, that you mentioned. SAFETY is my primary concern too! I want to be a part of the solution - not the problem (I know that sounds corny but it is really how I feel).

I was unaware of the accident statistics you report AND am very surprised the accident rate is so remarkably high. I was also unaware the British Government had gotten so strict with their Gyro Airworthiness requirements - 3 cheers for them!

It is the lack of insurance availability for Gyro instruction that caused me to find a deal on an RAF 2000 that I just could not turn down. I can only imagine the 'pile' of Liability waivers you would have me sign to take instruction at Auburn, since no insurance is available to you. When will your RAF 2000 Stability Augmentation Kit (SAK) go on sale? Will you give me a BIG HUGE discount on the SAK if I take instruction from your instructor? Please do not answer that - I am just poking a little fun.

As I have repeated several times in this FORUM I like the SparrowHawk and its CLT and several other aspects of it - BUT it needs to be flown and tested in the real world where the real 'bugs' can be sniffed out and corrected. You are a real believer in SAFETY and I would not ask you publicly to say anything against your product. However, can ANY aircraft so new to the marketplace be considered safe yet - I think not! Does that make it fall into the UNSAFE category? ABSOLUTELY NOT! It just hasn't had time to prove itself yet - and that is what safety is all about...just my opinion.

If you would send me some info privately on everyone's availability at Auburn I will try to work a visit in.

oldpilot

09-12-2004, 09:19 PM

Kevin Richey,

Thanks for the info and unraveling a 10 yr old mystery for me! I sold the place in Wilsonville (12 acres) and moved to the Stafford area and 3.5 acres.

KenSandyEggo

09-13-2004, 12:18 AM

"When will your RAF 2000 Stability Augmentation Kit (SAK) go on sale?', Steve asked.

Steve, look at my Avatar or whatever that little photo is called. Also check out the gallery at the AAI website. Every gyro pictured shown except 1 or 2 is an RAF with the SAK. Mine was the first customer conversion and I think that must have been a couple years ago.

www.americanautogyro.com

steveb

09-13-2004, 03:59 AM

Randy

Just to put a British spin on what has happened here, the UK CAA brought in increased gyro airworthiness requirements following the disasterous arrival of the Air Command gyro over here in the late 90s.

The result of the new requirements (contained in BCAR Section T) has not been a root-and-branch change to the way in which gyros are built here - what it has in fact done is effectively prevented any new designs (and by that I include safer ones) being introduced as the cost of demonstrating compliance is too high for most individuals to contemplate (or commercial organisations to take on given the size of the market). Instead we are all flying the same machines as we were in the late 90s (including the un-stabbed RAF 2000), which were approved by the CAA before the new regs came in.

Ironically the only gyro to have been approved through the entirety of Section T is a modified version of the CLT Air Command.

Dean_Dolph

09-13-2004, 08:51 AM

Hey, SteveB, could we get you to complete your profile?!

I'm glad you provided some local input before I made a reply to Steve Beck. Your reply pretty much backs up my gut feeling from little bits and pieces of info we get here on your regulations and Section T.

I feel sorry for you guys and don't agree that the British government needs to get three cheers! While it is good that they care (I think!) it is also disturbing when there is over reaction to a situation where more harm than good is the result. The U.S. is having the same problem in reacting to 9/11/01. Some people think it is better to do something, anything, even if it turns out to be the wrong thing to do. I don't agree.

Aussie_Paul

09-13-2004, 02:58 PM

Yes Stan, the NZ one was made by my friend after I got him organised with the neccessary parameters, and the testing that I did as he does not fly, and is a theory man. I conduct the proving practical testing.

Aussie Paul.:)

Aussie_Paul

09-13-2004, 03:52 PM

Oldpilot Steve, I am a very lucky fella. I have been fortunate enough to have conducted probably the most R&D on Raf pitch stability than anyone else. I had to. I spent me money and received a pitch unstable quite dangerous machine that was almost impossible to teach productively in. I trusted the Raf management that the "magical" bush and the control geometry worked as an H/stab. I was concerned as I had proven over the years that a stab made training much more productive.

I found eventually that I had been lied to and fitted a stab. I worked up from the too small flat plate stabs to effective airfoil shaped stabs, and was quite happy with the results. The forum guys back in the days of Norm’s forum told me that my "bandaid" fix was better than nothing but that the real problem lay with the high thrust line to CoM offset. Their explanations made sense to me and so I developed Hybrid. Hybrid uses the Raf cabin and quite a bit of the airframe and control systems etc. I replaced the Raf best drive with a Hirth gear box and turned the gearbox around compared to almost everyone else. I stepped the keel and was able to lower the thrust line 5". That meant that the engine now had to me attached to the mast 7" higher.

Because the prop is now going in the opposite direction a new tail had to be made. As the Raf with the doors on is quite yaw unstable we made the tail 30% larger. That solved the doors on yaw instability. The first test flights were conducted with a Raf rotor head and Raf blades. I had to hand spin the Raf blades as I did not have a pre rotator. At this point Hybrid did not have a stab fitted.

Hybrid without a stab flew much more stably that a Raf with a stab!!!! Wow I was pleased. We added a small stab and I could fly circuit after circuit with the stick locked against the dash. After lift off and attitude set for 55 mph I would lock the stick against the dash with an adjustable for various speeds, bar. I could fly the circuit using power, roll and rudder BUT no pitch control what so ever. I would begin the flare and the lock would drop out and I would finish the landing. I would take off and repeat the performance. I must tell you that this was a very exciting time for me.

Since then we have experimented with various rotors, pre rotators, props, gearboxes, rotor heads with various offsets, and some different designs of h/stabs etc. We have now found that since we have the airframe stable with CLT and an h/stab, that various brands of rotors can have quite different stability/instability characteristics.

I have developed a set of modifications that make a Raf a much more use friendly machine than just adding a stab. These certainly are not necessary for reasonably safe flying as Stan and the stabbed Raf guys are finding. I have developed the next level of safety for the extremely large thrust to Centre of Mass (CoM) offset of the Raf. These extra mods make the machine a much more productive training machine, as I can let the student get closer to the “edge” without worrying. A lot of instructors take over too early. I like to have my training machine and know that machine so well that I can let the guy go to the point that he thinks he will lose it, and still be able to talk him back without running the risk of dying, and me having to take over. That is very productive training for the gyro pilot to be.

These mods require very little financial outlay. Just some cutting, drilling, and spanner work, and a couple of 3/8” rod ends and some ¼” plate approx. 8” X 12”.

Using my mods and a stab with vertical fins to help with the doors on yaw instability, is the best Raf that can be made.

Wow!! I have got carried away a bit, but there have been numerous new members to the ever growing Todds forum, so I hope that the old timers will put up with my ramblings for the benefit of the new members.

Aussie Paul. :)

Shadow

09-13-2004, 05:30 PM

I have developed a set of modifications that make a Raf a much more use friendly machine than just adding a stab. These certainly are not necessary for reasonably safe flying as Stan and the stabbed Raf guys are finding. I have developed the next level of safety for the extremely large thrust to Centre of Mass (CoM) offset of the Raf. These extra mods make the machine a much more productive training machine, as I can let the student get closer to the “edge” without worrying. A lot of instructors take over too early. I like to have my training machine and know that machine so well that I can let the guy go to the point that he thinks he will lose it, and still be able to talk him back without running the risk of dying, and me having to take over. That is very productive training for the gyro pilot to be.

These mods require very little financial outlay. Just some cutting, drilling, and spanner work, and a couple of 3/8” rod ends and some ¼” plate approx. 8” X 12”.

Using my mods and a stab with vertical fins to help with the doors on yaw instability, is the best Raf that can be made.

Aussie Paul. :)

Can you list/discribe these mods for us? Does it make it as good as the Kiwi boys bird? :confused: :)

oldpilot

09-13-2004, 07:27 PM

Aussie_Paul,

You Da Man! Where will I find the specifics of the mods you developed for the RAF 2000. You 'baited' me (us) and just left me (us) hanging there? Do you have any photo's to post?

I want to thank you for jumping in and giving us Gyro 'challenged' and lesser experienced pilots some insite and background.

Looking forward to your reply.

John_wilkinson

09-13-2004, 10:59 PM

Our RAF here in New Zealand was modified with Paul Bruty's input and suggestions as when I was over in Australia being trained by Paul, I helped him finish off one of the first chopped keeled RAF's and came back to New Zealand with the idea of doing something along these lines whilst waiting for Firebird. Each machine that has been done in New Zealand and Australia has been taken a little further to find the best combination. This alteration has been highly supervised by Paul Bruty and test flown up to this date, each machine. That is why we imported Paul to New Zealand to test our machine and set it up. His knowledge and capability of fine tuning a machine is second to none that we have encountered.

Doug Riley

09-14-2004, 09:06 AM

Oldpilot: A couple comments:

(1) I flew in a Sparrowhawk at Bensen Days this past April. It was a quick ride, but very pleasant. The machine flew much like my tandem Dominator, which is to say it's very user-friendly. It did feel heavy (perhaps because it is). Climb was not awesome, but was adequate, even in the Florida heat. I imagine that some tweaking of the engine-prop combo could improve performance.

(2) Back to H-stabs: A small, stubby wing (which is what a HS is) can be either a flat plate or a true airfoil. The performance penalty for using the simple plate is not as great for this type of airfoil as it would be for a main wing. A true airfoil stalls at a higher angle of attack, however, at least if the leading edge radius is no sharper than the airfoil specs require. A NACA 0012 is the "default" standard tail surface foil.

As Paul Bruty reports, simply adding a HS to a stock RAF is not a full fix for the high-thrustline problem. Both the "numbers" and actual test flights agree on this point. It certainly brings an improvement in handling, but some level of PPO danger remains. Solving the problem completely requires getting the prop centerline closer to the aircraft's center of mass (CG), as Paul and Sparrowhawk have done.

Doug Riley (old pilot, too)

oldpilot

09-14-2004, 10:00 PM

Doug_Riley,

As I have said all along...time will tell on the SparrowHawk. The members of this FORUM will test it and in about a year we will all know if it can live up to the claims made on its behalf. My money says it will come close but I didn't become an "Oldpilot" by being hasty.

Thanks for the info on the default standard for a tail surface (NACA 0012). This is the first reply that actually provided an airfoil number for the tail feathers - just what I was looking for.

Just for the record - I realize that a HS and CLT must be added to a RAF 2000 to make it more 'safer' (stable).

I appreciate your comments and concern for safety and for replying to this thread.

~Oldpilot~

GyroRon

09-15-2004, 03:43 AM

Will there be any glitches with the Sparrowhawk??? Maybe so, they already had a front landing gear problem. So it is safe to assume they might end up with another problem here or there. BUT.... for those who have really looked a Sparrowhawk over, it is clear that it is more or less a copy of several different gyroplanes that have been on the Market for quite a long time. I personally would trust it.

gyromike

09-15-2004, 06:52 AM

Oldpilot,

Here is a writeup of my Sparrowhawk ride with Terry Eiland:

http://www.rotaryforum.com/forum/showthread.php?t=189

steveb

09-18-2004, 10:27 PM

I had a flight in an AAI Modified RAF.

The flying characteristics were a "no-brainer" - it was stable and easy to fly. There were some features which bothered me:

- The nosewheel steering was unacceptably heavy (almost to the point of being unusable). It took a huge amount of effort to make the aircraft turn on the ground, and would have been impossible for a small / weak person to control

- Lateral stick forces seemed very high (caveat - I've not flown another similalry heavy 2-seater (I trained in a VPM) so I don't know whether this is typical of machines like this)

- The rotor arc passes through the vertical stabiliser with the stick fully back before the blades are up to speed. In my view this is a less tha desirable feature (just ask Ken J what happens when you take your eye off this ball ....). Means that teeter stops are a "must-have".

I'd like to see some real-world performance stats for the Sparrowhawk.

oldpilot

09-19-2004, 07:41 AM

steveb,

As I have said all along...time will tell on the SparrowHawk. The members of this FORUM will test it and in about a year we will all know if it can live up to the claims made on its behalf. My money says it will come close but I didn't become an "Oldpilot" by being hasty.
~Oldpilot~

Could the features which bothered you be unique to that particular Gyro or do you believe they are all set up that way when the AAI modification kit is installed??

Your last issue is particularly bothersome - about the rotor striking the tail!!

I am starting to see other "issues" being reported on this forum. The latest one is about the tail waiving. There are explainations for it, including a lengthy one from Jim Mayfield of AAI.

However, if we are intellectually honest, we all know this bird is in the flight testing phase and these issues are EXACTLY what we want to be revealed so they can be dealt with and fixed.

Thanks for the report steveb, we all benefited from your experience.

~oldpilot~

oldpilot

09-19-2004, 07:56 AM

Mayfield

09-19-2004, 08:37 AM

Good morning old pilot. (I would call you by your first name if I knew it)

I agree that it is important to try and get as much as possible understood.

I hope I do not sound argumentative. It is not my intent.

I, personally, am not aware of any gyro that will not have the rotor intersect the tail with the rotor stopped, or just starting to rotate, and the stick full back. I know for certain that the RAf, A&S 18A, Bell Jet Ranger, Robinsons and others will.

I suspect, but do not know, that Ernies blades are stiff enough that they do not droop much statically and so probably do not intersect the tail unless you pull down on them or start prerotation in gusty conditions with the stick full back.

That's why all gyros start pre-rotation with the stick forward, and all helicopters start rotation with the stick centered.

In flight there is almost 4 feet of rotor to tail clearance with the SparrowHawk.

Thanks Old Pilot. This forum is a wonderful tool for getting info out to the community.

Jim

oldpilot

09-19-2004, 01:59 PM

Mayfield,

Thanks for the clarification on the rotor striking the tail on start-up. Your post was not arguementative but factual and many will benefit from your explaination.

BTW I am fully listed on the MEMBERS list of this forum (name and all :-).

~oldpilot~

Aussie_Paul

09-19-2004, 02:23 PM

Jim, I am not being argumentative, but the problem is with blade flap on take off as Ken J found out. I used to argue with Don at Raf that "I know if you take off as per the flight manual that it (rotor strike) can't happen, BUT, I do and many othere probably as well stuff up occaissionally. You have to design for the weakest link,ME."

Your Sparrow Hawk problem is easy fixed with some form of rrpm engaged teeter stopper. Rafs main problem is that they insist on having too much teeter and too much back stick availible.

Keep up the good work and honest reporting, Jim.

I am learning from your attitude!!!!

Aussie Paul.:)

Mayfield

09-19-2004, 02:50 PM

Hi Paul,

Centrifugal droop stops are standard on the SH now. They fling themselves out of the way at about 100 RRPM.

R/S

Jim

r.coplen

09-19-2004, 05:00 PM

Steve,

Sorry I didn't get back to you sooner. I have been busy with the flight school and beginning ground tests on the SparrowHawk. I also have been hosting a number of people in from Japan. I am not able to take as much time to be on the forum as you can.

The rudder controls on Ruby are firm but I have not had any of my students express any negitive concerns in their lessons. With the tail rudder and the nose wheel working together the students are able to turn the gyro quite easily on the ground.

I don't know how to respond to the negitive comments about the SparrowHawk or the mod RAF as I or my students haven't experienced these issues.

Randy

GyroRon

09-19-2004, 05:51 PM

I can't push the blades into the tail on my Dominator even trying. They can come really close to the ground though if I push them to the stops and the gyro is on the tailwheel.

steveb

09-20-2004, 12:19 AM

No aircraft is perfect - they are all compromises and have good points and bad points.

As Jim has reported teeter stops are standard on the Sparrowhawk, so the blade through the rudder issue is sorted (btw the rotor on my single seater, or any other UK single seater, doesn't pass through the rudder. The same is true for the VPM as far as I know).

I'm pleased to hear that other people haven't found the same problem with the nosewheel steering. It might have been specific to the aircraft I was in, or may have been fixed in later iterations of the upgrade kit. Anyway, we need to keep these things in perspective - heavy steering is a small price to pay for an aircraft which is so much safer than a standard RAF 2000.

birdy

09-20-2004, 01:32 AM

Paul B,I too am supprised at how much teeter is built into some rotorheads.Neither of my machines blades will come close to the rudder or the ground.[wot is the ruel of thumb minimum teeter alowable?????]

But as someone said before in another way,if you'v got your hand on the wrong stick,your go'n to damage sumth'n.

Aussie_Paul

09-20-2004, 03:28 AM

Birdy, teeter is not built into the rotor head. Maximum pitch control movement is, and should be around 18 degrees.

Teeter is made up of teeter bolt height in the teeter towers and the undersling of the rotor.

With a pre rotator you can get away with as low as probably 10 degrees maybe less, but slowing the rotors down on a windy day can end up with rotor flap. Without a pre rotator you need approx 18 degrees to get the blades over the first hump.

Aussie Paul.:)

Aussie Paul.

birdy

09-20-2004, 05:51 PM

I thought the amount of teeter was how many degrees the hub bar could hinge between the stops.

But your right,it can be a barsted to catch the blades in a gail.Never thought of that.
Good thing I got a well set stick lock ay.

rfi

09-23-2004, 12:22 PM

Paul, are you talking about +/- 9 degrees on the teeter or a total of 18 degrees in pitch?

rehler

09-23-2004, 01:28 PM

Birdy, you asked: "wot is the ruel of thumb minimum teeter alowable?"

The "normal" teeter is 9 degrees down and 9 degrees up for a total of 18 degrees. Also the rotorhead torque tube tilts 9 degrees forward and 9 degrees back for a total of 18 degrees (also left and right). So, the rotor blades can be 18 degrees forward down to 18 degrees read down, making a 36 degree total maximum allowable tilt.

This does not answer your question as to "minimum", but it should not be too much less than the "normal".

Brian Jackson

09-23-2004, 04:30 PM

Thanks, Ken, for the teeter/head angular info.
Little by little I'm cataloging bits of useful information in a series of Gyro-related text files... more of a copy-&-paste thing, but since there's no official "Gyro Design College" I guess I earn my degree here!

Appreciatively,
Brian Jackson

Aussie_Paul

09-24-2004, 12:53 AM

Both Don. At the moment I am running 14 total teeter with my rotors. The reason for this is that I had some towers that fitted and I ended up with 14*.

I always like a total of 18 or 20 degrees in rotor head pitch movement. I like 18 back and 1 or 2 degrees negative with full forward stick. This helps to slow the rotors down if you cannot get the wind behind you. If you have too much negative and you go to full forward stick after landing with considerable rrpm the rotor can pull you along and off the runway if the stick is not central.

Is that the info you were after?
Aussie Paul.:)

birdy

09-25-2004, 06:17 PM

Thanx Ken.
It's just that I see a big vairiation in different desigens and wundered why.Both my machines have very little teeter but they'v never hit the stops in flight[not that I'm aware of anyway].I'll put the bubbleometer on them later and check wot they read.

Aussie_Paul

09-25-2004, 09:40 PM

You probably would not be posting. The other day I was testing some Jack allan wide chord blades set to a little over 3 degrees on the pitch blocks. The blades are 25' and the machine an ea-81 with a belt drive and a 70" 3 blade W/drive.

The day was bowing over 10 kts and boy did we whae a battle hand start them!!!!!! On the take off run after gently allowing the blades to get up to quite a blurr I opened the tap and the blades just started to hi speed flap!!!! (Hit the teeter stops.) I was quick enough to reduce power as I was very on the ball all week testing Dewies machine. We had adjusted the blade pitch with the rotors on the machine, and thought that we only tweeked a line width. When I came back after a circuit we removed the blades and measured 3 degrees!!!!!!!!!!!

We have them now set at 2.1 degrees at the moment, and they are going reasonable. As I have always believed, they are great blades for carrying heavy loads at a slow speed.

Mceagle Tim might comment on his findings of these blades, over the years.

This machine of Dewies was obviously built by someone who knew veryy little about gyros. This someone had rolled it twice. I certainly did not have time to make a mug of coffee on the first take off!!!!!! :eek: :eek:

I will start another threat with the weeks progress.

Aussie Paul. :)