New raf / sparrowhawk

LARRYEBOYER

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Here's a picture of my RAF with a Sparrowhawk augmentation kit installed.I figured out how to mount the wheel pants which I think make it look classy. Just got the 40 hours flown off so time to give my EAA and PRA friends their long awaited ride. Have patience as the line is long.
 

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How do you like the flying/handling qualitys as compared to your other RAF,I have heard

that the really tall tail changes the handling,and there are some that don't really like

the way it flys ?




Best regards,
 
Toughkenamon

Toughkenamon

Hi Larry;
Will you be at the Toughkenamon (N57) Fly-In on Oct 8?
-Kurt
 
I like flying the New one, but it is not as stable as my last RAF. The Boyer mod was truly the fix for the RAF. I would fly that machine in20 mile gusty winds with no reservations whatsoever. This machine would be a handful.I am actually thinking about a change to this machine that would be inovative and fix the squirrelly nature in the current configuration.
 
This machine would be a handful.
That surprises me. Could you be more specific?

Thanks, Kolibri
 
Congratulations Larry, way to go.
Be looking forward to learning how you improve her so I can pass it on to others who may ask.
 
hey Larry good to hear from you, sorry I had to cut it short.

I think your boyer mod RAF was the better looking of the two and probably the best flyer.

What we talked about will probably be a good move.



Best regards,
 
I like flying the New one, but it is not as stable as my last RAF. The Boyer mod was truly the fix for the RAF. I would fly that machine in20 mile gusty winds with no reservations whatsoever. This machine would be a handful.I am actually thinking about a change to this machine that would be inovative and fix the squirrelly nature in the current configuration.

With your HS, I haven't found my gusty wind limit yet! When my FW brothers are grounded due to nasty, gusty winds, I'll go out and shoot a bunch of TOL's, I love it.
 
This article explains why a tall tail doesn’t work on an RAF gyro. The animation illustrates the phenomenon very well.

https://en.wikipedia.org/wiki/Kármán_vortex_street

Pat McNear solved the problem on his RAF by installing a belt of turbulators on each side of his RAF cabin just aft of the doors and picked up several mph of cruise speed in the process.
 
Kolibri, To try to explain my comment" It would be a handful". My previous RAF was a spoiler. It flew itself , literally .Windy days were fun. The drop keel, lower thrust line with my stab was the perfect fix. I have never flown a better gyro. I had a CLT air command that was good, but not as good. Benson? Nah! Standard RAF. OK, but no cigar. RAF with stabilator and stabilizer, solid. Well, you get the idea. This RAF with the sparrow hawk configuration is OK but it gets pushed around in wind. Just doesn't have that solid feel like my last one and I can't let go of the cyclic for long, that I don't have to grab it back. Guess I was spoiled. I flew a Sparrowhawk years ago with Terry Ireland. I got criticism because I thought the controls were to stiff and it seemed to wiggle around . I said I liked my RAF drop keel much better. Since the RAF was a death machine, and Groen brothers were aircraft engineers, I didn't know what stability was or what I was talking about.Now that I own one, I believe My original comments and original experience are accurate. The picture displayed n this post is the machine I felt was the best I had ever flown. It was the first drop keel machine I had done. I miss her. ( tear)
 
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Mr. Beaty. Thank you for that but over my head. The video does suggest why the ass end wiggles.In your opinion, would a stab mounted farther back than current Sparrowhawk design and lower than the cabin be a better solution? Thank you for your experienced opinion.
 
Properly adjusted rudder cables and a correctly adjusted an anti-servo tab made most of the modified RAF’s I have flown fly pretty well. The cables had to be tighter and had more drag than I liked.

All of the modified RAFs I have flown had power/pitch coupling and some power/yaw coupling. Add power nose up.

The unmodified RAFs I have flown with the short tail and a horizontal stabilizer had power/pitch/yaw coupling.

All would fly steady at a constant power even in turbulent air.
 
The problem is the result of the RAF cabin shape and there isn’t much that can be done about it other than installing turbulators/vortex generators.

http://www.airtab.com/

A low mounted vertical tail may be below the vortices coming off the cabin but won’t provide much redder authority.
 
Alternately shed vortices caused “Galloping Gertie” to collapse and fall into the Tacoma Narrows.

https://www.youtube.com/watch?v=nkXl8JJBH7E

A row of grating panels in the roadway could have prevented this by spoiling aerodynamic lift as could have spoilers at the edges of the roadway.

Whatever the case, tailwaging in an RAF and “Galloping Gertie’s” galloping is the same phenomenon.

Adding friction to the rudder is like trying to cure gonorrhea with a Band-Aid.
 
Try this one

Try this one

See the difference,
The engine is below the prop position,
The entire machine is Not as Top Heavy as the standard Sparrow Hawk mod setup.

And it's about 10-12 MPH faster at the same RPM, because of the narrow cabin width of the RAF cabin..
This one was Built by BO Collins...
 

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Kolibri, To try to explain my comment" It would be a handful". My previous RAF was a spoiler. It flew itself , literally .Windy days were fun. The drop keel, lower thrust line with my stab was the perfect fix. I have never flown a better gyro. I had a CLT air command that was good, but not as good. Benson? Nah! Standard RAF. OK, but no cigar. RAF with stabilator and stabilizer, solid. Well, you get the idea. This RAF with the sparrow hawk configuration is OK but it gets pushed around in wind. Just doesn't have that solid feel like my last one and I can't let go of the cyclic for long, that I don't have to grab it back. Guess I was spoiled.
Thanks, Larry. I'd like to fly a dropped-keel RAF someday.

_____
I'm keen to clean up my RAF's vortices as I can, so thanks for the info there. You'd think that RAFSA would jump all over such an easy mod to increase cruising AS.

Regards, Kolibri
 
I've said this before, Larry's drop keel and HS makes for a kick ass machine!
 
Thank you Mr. Beaty. I remember when Pat did that, but I don't remember him having the tall tail. I never felt the tail shake in a standard RAF . Maybe because it was far enough back. Not like the modified RAF with the Sparrowhawk change. Steve, you mentioned that engine drop idea to me at Benson a Days. I don't know why I didn't think of that when I was doing the changeover to the Sparrowhawk. Dah!
Eddie, you are right on the solid flying characteristics of the drop keel, lowered engine RAF with the stab. Well, now I have to modify my Sparrowhawk to get that RAF stability back. Like Greminger says" Way back".
Peaves me that I sold or gave away a lot of the parts I didn't need when I changed over to the Sparrowhawk like landing gear and engine drive plate. I might have to go on a parts quest. Just disappointed the Sparrowhawk didn't deliver more stability. After all, it was developed by engineers.
Any suggestions on simple improvements or adjustments from a Sparrowhawk owner would be greatly appreciated. Also, Mr Beaty, I may order the Airtabs. Makes sense.
One other thing. The RAF is fast with the EJ25. I have the 4 blade Warp 72 inch on it and it cruises easily at 90 at 4350. Or 80 at 4150.
 
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Pat didn’t have a tall tail but as nearly as I can recall, he was bothered by tail wagging when the doors were installed; doors off, no problem.

The turbulators/vortex generators solved that problem and gave him a bit more cruise speed. His gadgets, I think, were strips of zig-zag vanes.
 
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