+ Reply to Thread
Page 1 of 5 12345 LastLast
Results 1 to 15 of 63

Thread: Gyro prerotator

  1. #1
    jim
    jim is offline
    Registered User
    Join Date
    Jan 2003
    Location
    Wisconsin
    Posts
    3

    Gyro prerotator

    Hello,
    It looks like I'm the first one to post on the rotorcraft thread, so I hope there's someone out there sooner or later with some Gyro expertise!
    I've recently accured a gyro That I plan on rebuilding after I finnish my plane. I would like to know what the average take off distance is with and without a prerotator? This gyro doesn't have a prerotator and at this point I don't know if I would be able to install one until I check to see how close it is the the 254 LB limit.
    Any advise would be appreciated!
    Thanks,
    Jim

  2. #2
    Administrator
    Join Date
    Aug 2002
    Location
    Savannah, GA
    Posts
    51
    Jim,

    Someone had to be the first! Thanks for the post. I think, as things get going, there will be more and more experience to draw from in the future. We are a brand new community so things are a little slow yet but it won’t be long before this place really takes off.

    There is a forum dedicated to Gyro's over at http://pub23.ezboard.com/btheflygyroforums that might be of help to you as well.

    Let us know how it turns out.

    Jake

  3. #3
    Registered User
    Join Date
    Feb 2003
    Location
    Punta Gorda, Florida
    Posts
    17
    Do you know what design it is? Take off will depend on a lot of parameters such as: Style of rotor, Diameter and pitch, Gross weight at takeoff, HP (Thrust) and pre-rotator speed. Altitude is also a factor.
    For example, I am building a "Gyrobee" with 40hp, weight is 252 lbs and with pilot and fuel I expect to be 'bout 510 lbs. By hand rotating, (before starting the engine for safety) I expect to push 95-100 rpm. Jumping in, belting up, helmet, and start engine, (already warm) I should still have 90 rpm, enough to not have "blade flap" Take-off run at near sea-level will probably be less than 400 feet, with 800'/" climb. About 800 feet over 50ft obsticle.. This is typical and I hope mine will be too. I'd love to hear more. What power etc.
    Skip 3i

  4. #4
    jim
    jim is offline
    Registered User
    Join Date
    Jan 2003
    Location
    Wisconsin
    Posts
    3
    Skip,

    Thanks for the reply. I didn't think one could hand spin the rotor up that fast!
    I aquired my gyro from a person who had taken the rotor off and ran it down the road to see how fast it would go!!..... Well, he said he got er up to about 45mph and she started whipping and of course he tipped it over on it's side. He had never fly anything before and I think that he thought it was just a toy!. I swapped him an old motorcycle for it.
    So far I've replaced the damaged landing gear, and have the material to change the mast and a new rotor(which he threw in on the deal)
    The gyro looks like a gyro bee but the way some of the parts are finnished I suspect it's a kit.... but haven't run accross one like it.
    It has a 500cc suzuki 2stroke liquid cooled engine with a 23' rotor. I have it wrapped up right now cause I need to finnish a zenith ch701 so I can get the garage space. I really want to get it up and flying tho!

    Have you had any gyro training Skip?

    Jim

  5. #5
    Registered User
    Join Date
    Feb 2003
    Location
    Punta Gorda, Florida
    Posts
    17
    I have been a member of "Sunstate Wing & Rotor" which is associated with PRA, and EAA. for several years. I had a partner on a Benson B8, back in the 60's. After we bent it up beyond repair, I didn't fly much gyro for several years. When I recovered from growing kids and divorce, I got back into flying with Ultralights. I have several hours now in RAF gyro, but stopped when I realized I will never afford one $$. I switched to Air Command, open frame and that got me hooked again. A friend of mine built a gyrobee, and I really drooled when I saw how inexpensive it was to build and fly.

    Yes 90 to 100 rpm is possible with the aluminum blades. I wouldn't even try with the heavy composite blades. Some pre-rotation is neccessary to keep the blades from going into a teeter totter flap, that is destructive. If the guy had known much 'bout the gyro he would have realized that without the stability from the rotor, the cart was just an accident trying to happen. If you haven't had much experience w/ gyro's, PLEASE get dual instruction. It is the best insurance you can have. And it's cheaper than hospital bills. In the early days we lost a lot of pilots because we didn't have instructors. I will be taking instruction before completing my Gyrobee, even though I have flown for years, but not recently.
    Skip 3i

  6. #6
    Registered User
    Join Date
    Feb 2004
    Posts
    63
    http://www.rotorcraft.com/forums2/
    www.rotorcraft.com

    These guys really know stuff about gyro's.

  7. #7
    Registered User
    Join Date
    Nov 2003
    Location
    At the present, Peru
    Posts
    3
    Originally posted by skip_hill
    Do you know what design it is? Take off will depend on a lot of parameters such as: Style of rotor, Diameter and pitch, Gross weight at takeoff, HP (Thrust) and pre-rotator speed. Altitude is also a factor.
    For example, I am building a "Gyrobee" with 40hp, weight is 252 lbs and with pilot and fuel I expect to be 'bout 510 lbs. By hand rotating, (before starting the engine for safety) I expect to push 95-100 rpm. Jumping in, belting up, helmet, and start engine, (already warm) I should still have 90 rpm, enough to not have "blade flap" Take-off run at near sea-level will probably be less than 400 feet, with 800'/" climb. About 800 feet over 50ft obsticle.. This is typical and I hope mine will be too. I'd love to hear more. What power etc.
    Hi,
    My name is Jim Hathorn
    I'm REALLY interested in building a Gyrobee...I'm in Peru at the moment but will build in Arizona...I see that you're located in Fla....I'm coming next week to Miami area for my girlfriend's nephew wedding...Would like very much to touch base with you...Any information I can get would be greatly apprecated...My email is...wimpy35@hotmail.com
    thanks,
    jim

  8. #8
    Registered User Bob Kelly's Avatar
    Join Date
    Aug 2004
    Location
    N.Calif Mountians
    Posts
    387

    Gyro Prerotator

    IN responce to your question about the pre-rotator ...
    it sounds like your craft just might be a Bumble Bee the same thing i have .
    i do know that the prerotators were an option
    for the kit.
    ... i bought mine at a yard sale in a heap
    took the pieces home and re-made it ..
    replaceing the missing and broken parts.
    .... my first test flight got me off the ground
    in about 50 feet after turning the blades as fast as i could with the Pre-rotator.
    I only left the ground for about a foot high
    and travled about 30 feet ... it was enough to show me it worked ... and enough to show me that the tricycle landing gear was dangerous !

    I have sense modified the thing a great amount, changeing it to a tail dragger and greatly increasing the horizonal stablizer and rudder SIZE by almost double for the rudder and almost tripple for the Horizonal stablizer.

    I spent all summer last year trying to get the beast in the air again ! but wound up
    flopping it over on its side ... needless to say that is very hard on the rotor and prop.
    .... after 3 attempts this happened....each
    had a sudden left hand turn just as i approached lift off... i saved it 2 times... the 3rd i didn't.... even though it slid brodside at aprox. 20 mph it almost didn't
    tip over... but alas it did....
    the rest of the summer was spent repairing
    the dammage i had done ....
    I discovered what it was that made it turn
    in such a nasty way.... I FORGOT to take off the PRE-ROTATOR ! ...so with it still enguaged as the wheels left the ground , the reverse torque turned the entire craft !
    I shall install a Light on the switch pannel
    that tells me when the pre-rotator is enguaged.... as a safty factor for future use.

    As she sits she is holding up fine under the snow load... soon it will be warm enough to try her again and this time i am sure i won't forget to disenguage the pre-rotator.
    ....
    I have the complete plans for this Bumble bee. and it includes the pre-rotator as well.
    I could draw them out for you if you'ed like and e-mail them to you

    its simply a pully behind the prop that turns another pully by a v-belt, that is fed into a 90degree gear box and a drive shaft and
    slip joint up to the mast, where it turns a big pully mounted under the rotor.
    its simple, efective and not very heavy at all.... but Dangerous if forgotton !

    hhehehehe

    Hope that helps
    Bob@eclecticwizard.com

    Bob...

  9. #9
    Registered User Sonnyj's Avatar
    Join Date
    Feb 2005
    Location
    Rosman NC USA
    Posts
    164
    Hello Bob
    I would be very interested too see the PR drawings if you have the time.I have a modifyed Benson That I have almost finished.
    How much do you think the unit weaghs?
    Thanx Sonny
    Intelligence is not a privilege,it is a gift,and should be used for the good of mankind.

  10. #10
    Registered User Bob Kelly's Avatar
    Join Date
    Aug 2004
    Location
    N.Calif Mountians
    Posts
    387
    Not that mutch at all actually !
    i'll dig out the plans ans try to draw them out for ya ... given dimentions on the pertant parts
    .... may take a few days
    this unit is quite nice actually ..it actuates by a lever by the pilot seat.... and will turn the blades up to flight speed or very close to it
    ... i'll get to it now .... perhaps you can give me your email address so i can send you a big drawing ...this site only likes tiny images i think.

    edited:

    the Link below has a drawing i did for ya ... kind of an over all view of how it works and how its set up.... if you are going to make one like it i can get ya the part numbers and pertaintant measurements that you'ed need.... but sounds to me like ya are more or less exploreing your options at this stage .... so let me know if ya want more info !


    http://www.eclecticwizard.com/bob/bbprerot.png

    Bob.......
    Last edited by Bob Kelly; February 14th, 2005 at 01:08 AM.

  11. #11
    Registered User Bob Kelly's Avatar
    Join Date
    Aug 2004
    Location
    N.Calif Mountians
    Posts
    387
    Sonnyj.....
    After going over my assembly manual i found there are 6 large pages having to do with the Rotor Pre-spin assembly ... seeings as how you wouldn't need half that information sense you are thinking on putting it on a Benson frame i think perhaps the general idea is all you need ....
    ( i had a older benson with wooden props way back when i was in Reno nv. never tried it though ...wound up selling it when we moved ).

    the Drawing i did for you explains most of the idea well.... the smaller pulley at the back of the mast that turns the pulley attached directly to the underside of the rotor is a ratcheting device... it alows the rotor to turn with out turning the drive shaft ... so with the unit turned off you can turn the rotor easily by hand .. even if the pre-rotator is enguaged and the engine not running. ...so the Main rotor will be free-wheeling in another words.
    .... the Sizzers action mech. that moves the pulley out to enguage the v-belt off the main shaft is simple and efecient .... the cable pulls down in the center of the 2 pieces of flatstock and simply pushes the
    pulley shaft. berring and all out till the v-belt is tight so it will transfer the rotation/power ..
    ... the Slip joint on this thing is unique indeed... it is simply a piece of 3/4" square tubeing with a piece of smaller 1/2" square tubeing slideing inside it... sense its square it can't spin inside oneanother ( obviously ) this slip joint is needed because the rotor head tilts at all kinds of angles ... and just below the ratcheting pully on the 1/2" square tube slip-joint is a 1/2" drive swivel socket or universal joint ( tool piece ... for your 1/2 " socket set !
    i thought this kind of the weak link in the chain but i have used the heck out of it and it shows no sine of getting loose or wareing out ....perhaps a universal joint off of a car steering wheel would be better ? but probly un nessarry.

    the 90deg. Gear box has the alum.tubeing simply pinned to it with a 1/4" bolt ( hole drilled through the shaft. )

    all in all ... every part included it probly only weighs aprox. 20lbs Max.
    all parts are alum . except the berrings ,slipjoint and universal joint and the ratcheting pully... and the pully behind the prop is of the automotive verity i think (pressed out steel ) the pulley directly under the Rotor is a 12" swamp cooler pulley with the center cut out and holes drilled to attach it to the Rotor-pivot block
    ...i had to replace this pulley when i first got the craft ( busted up bad ) and it was quite a chore getting it RIGHT ... with hand tools and a drill press.... there isn't much room for error at all there !
    .....
    Yes ...V-Belts.... the system is designed to Slip ...... and slip it does to some extent
    ... but it will get the rotor into the 200rpm range within 60seconds or so ...
    ....
    so spin the rotor up .... disenguage the pre-rotator ... taxey out and take off !
    .... just don't forget to disenguage the silly thing or you turn left at takeoff ! .... hard on a persons toy too ! heheheheh

    hope this helps ya !

    and good luck to ya !

    Bob.....

  12. #12
    Registered User Bob Kelly's Avatar
    Join Date
    Aug 2004
    Location
    N.Calif Mountians
    Posts
    387
    Oh Sunnyj !
    i just thought of the perfect answer for you...
    if your useing a Benson.... you may be useing an electric starter ...and have a 12 volt battery on board... if so here is the answer... !

    Buy a 12 volt lawn tractor starter motor ...
    put a ratcheing pulley on the end of the starter and mount it on the mast head... sense they are relitively light probly 5 to 10 lbs ...
    the weight problem of conventional electric starters just about puts them out of the running... but these starters are light and powerfull ... and use less amprage than auto starters to boot....

    you can find a few of these types of starters in your Northern Tools and Hydrolics mag... if you want ...go to their website at ...
    Northerntool.com
    ( i love these folks ... got all kinds of goodies ! )

    anyway ...sure beats padding the rotor up by hand !

    here is a link to my website my son made up for me in 10 minutes ...got some pictures you might finf helpfull ....
    http://www.eclecticwizard.com/bob/bobsbumblebee.html


    something to think about anyway !

    Bob......
    Last edited by Bob Kelly; February 14th, 2005 at 08:17 AM.

  13. #13
    Registered User Sonnyj's Avatar
    Join Date
    Feb 2005
    Location
    Rosman NC USA
    Posts
    164
    WOW Bob that is realy good!
    It looks like I may need some deminsions for the motor end pullys tho,I am using a direct drive so it turns backwards from yours,the rest I think I can figue out.
    I am trying to keep Gyro1 "thats her name"at part 103 so I dont have a battry or anything that dosnt have an internal power source.
    Any way it seems I have more parts to make,but thats the fun part aint it!
    Please give your son a big pat onthe back for the great job he did on your site,thats really cool! Myemail address is in my profile,it would be great to hear from you.
    Thanx Sonny
    Intelligence is not a privilege,it is a gift,and should be used for the good of mankind.

  14. #14
    Registered User Bob Kelly's Avatar
    Join Date
    Aug 2004
    Location
    N.Calif Mountians
    Posts
    387
    thanks for the flowers ! hehehe
    Motor end pully .... the one behind the prop is the exact same diamator as the one that drives the 90 deg. gear box (4"diam)
    .... but i have a 2.58 : 1 gear reduction on my Rotex 447 so .... yours will turn a bit faster than mine .

    As far as it Turning backwards ...that poses a problem.... because your Rotor will want to turn counter clockwise right ????
    using the setup i have here it would turn it clockwise .... Hummmm gott'a think on that ! gott'a be an easy way arround that but its late and i havn't slept in many hours ! so me brain isn't working ! hehehe...
    .........
    .... what kind of engine do you have on your beastie anyway ? I totally agree with keeping it within part 103 statis... Except when it comes to your safty so don't build it too light ! .
    ..........
    So ...i sujest the smallest pulley you can fit over the prop hub.... and go from there ...
    perhaps a slightly bigger pully on the gear box shaft ... the berring for that shaft is pressed into a alum. block 1/2" x 2" x3"
    ( hole drilled in the center of corse)
    that gearbox drive shaft from the pully to the box is just 1/2" steel rod you find at any hardware store ... pinned to a piece of
    Alum tubeing so it can mate with the gearbox ... very simple construction...
    i am supprised it holds up as good as it has !
    so in Reality you only have 2 berrings to worry about.... the one i just mentioned and the one at the top of the mast where the ratcheting pully sits on .
    .... another thing... the gear box must flex a bit ... not much but a little to accomadate the shaft moving in and out when enguageing and disenguageing... so Don't anchor it down with 4 or 5 bolts nice and tight ! hehehe i did ... had to un do it !
    .....
    when useing a tube of metal like this it is important to get a good snug fit ... so if you have to use a sleve of another thin-wall tube to get it nice and snug....do it !
    and don't crush the tube with the bolt you are pinning it with ..... snug is great ... the pin is takeing the strain , so a small diam case hardened bolt is a great idea . with ni-lock nuts !

    Holler if you need the part number for that ratcheting pully .... it came originally with the kit this thing was made from...
    but i think there are manifactures listed in the manual ...and part numbers !

    Most people would be supprised at what a bit of tinkering and messing arround with pieces can accomplish ! just use your Head ! <GRIN>

    Have Fun my friend !

    Bob......
    Last edited by Bob Kelly; February 14th, 2005 at 01:00 PM.

  15. #15
    Registered User Sonnyj's Avatar
    Join Date
    Feb 2005
    Location
    Rosman NC USA
    Posts
    164
    Hello Bob
    I realy preciate all the good info on the P\R.After settin and figurin it looks like it's gonna cost less than $200 bucks to make, witch sutes me fine,the clutch bearing being tha most spendy part,thank goodnes I had the good cents to pick that lath and mill.
    The fix on the drive is perty easy,instead of running a belt and pully system,I'll make a drive wheel setup,one aluminum and one rubber.
    The motor I have is a72HP Mac it's an old milatary surplus drone engine whitch only weaghs 70LBS without the prop.
    Any way I'm collecting the stuff to build the aluminum blades now so I'l add the P|R materals to the list.
    Thanx Sonny
    Intelligence is not a privilege,it is a gift,and should be used for the good of mankind.

+ Reply to Thread
Page 1 of 5 12345 LastLast

Similar Threads

  1. Setting up a gyro for rough feilds.
    By Bob Kelly in forum Rotorcraft
    Replies: 12
    Last Post: January 31st, 2013, 04:28 PM
  2. Bensen Days Gyro Fly-In
    By gyromike in forum Rotorcraft
    Replies: 1
    Last Post: May 3rd, 2008, 07:00 PM
  3. The Perfect Gyro Copter ?
    By Bob Kelly in forum Rotorcraft
    Replies: 6
    Last Post: February 28th, 2008, 11:57 AM
  4. Good artical For Gyro pilots !
    By Bob Kelly in forum Rotorcraft
    Replies: 1
    Last Post: April 23rd, 2005, 06:15 AM
  5. How big of a rudder is safe .. on a Gyro ?
    By Bob Kelly in forum General Experimental Aviation Questions
    Replies: 1
    Last Post: August 26th, 2004, 05:30 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts