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 Tandem Dominator Measurements 
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Joined: Sat Jul 19, 2014 4:29 am
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Willing to pay 100.00 for general measurements of a Tandem Dominator. Want to draw it up.in CAD and CNC all the cluster plates. Trained with Davy Seace in his Olive Drab machine and just loved the way it flew.


Fri Jul 08, 2022 11:32 pm
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I don't have it, and gosh I have asked many times...on the rotary wing forum, no one accepted to let me know anything .
I was explained that there were rights ont it and that it would be a sort of patent infrigement to "steal" the mesurements ... even for a private gyro in france
to be clear they did not want to be acomplices of a crime ... hilarious to be honest ..
I simply learnt to desing a gyro ... and I made my dom's clone ..

Image

designing a gyro is not so difficult ... I did it ... (an evidence that even an idiot can...) ....the thing is that it takes more time for idiots .. took ages hahah


Last edited by Girodreamer on Sat Jul 09, 2022 2:49 pm, edited 1 time in total.



Sat Jul 09, 2022 1:48 pm
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You did an excellent job on your machine. I posted here knowing the RWF would be of no help. I have a Single place Dominator, for starting the design. I will probably get a good side profile off the internet and import it into Autocad as a PDF then scale it up with known measurements. The tail is 68" tall, keel is 3" tall,


Sat Jul 09, 2022 2:29 pm
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you know what ... RWF became a like a Harley Davidson, or BMW forum ... they spend their time speaking about what they have just purchased ...

yes a side pitcure will help of course

I will tell you how I did the job , it is easy and there is not problem because you can move pilot and passerger a bit (on your cad so)

don't panic ...

at the end of the day you will hang your gyro and verify it is at least pitching 8° forward ... it did it as accuratery as possible and when I haged the bird it was ok ... not okish .. ok

I did not tested the bird for divorce reasons hahaha (this message will be deleted..) but I hope it will fly nice ... hahaha I have no doubt .. LTL tall tailed gyro all fly nicely ..

if you have questions just ask me I will tell you what I think I know (I am not ernest boyett but ok my first gyro flies well ...)


Last edited by Girodreamer on Sat Jul 09, 2022 4:45 pm, edited 2 times in total.



Sat Jul 09, 2022 3:00 pm
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I am sure you know all of this .. but ok it will be useful for future newbies ..

any gyro can fly if the following rules are respected ..

the gyro, hanging by the rotor head (with control on neutral position) must pitch nose down 7°/8°... some say 5°/ 6° .. dom's prop pushes under the center of mass .. (nose up moment) so 8° is a minimum for me ..

all of this with pilot and passenger on board and and full fuel (some say half of the fuel .. but if you neutralize fuel don't bother with this)

standing on the ground the rotor must not touch the tail when tilted 20° backward ... at least it is better hahahaha .. stupid froggy (me)

stick fully ahead rotor must be horizontal

stick right the rotor must tilt 8° right ... (at zero flapping angle of course)

same on the left...

the main wheels must be under the rotor head at max 10 cm behind but not more .. this is the tricky thing ... because if you fail your horizontal Center of mass on the cad and correct the weights and balance by moving the rotor head, it will change the horizontal distance btw wheels and rotor head ..

when the wheels are too far behind, the front wheel won't lift as soos as the rotor lift appears .. (it will lift a bit later and more "violently")

if all those rules are respected you are sure that your gyro will fly well and that you won't reach your pitch control stops.... (you will be able to correctly get your descent airspeed and flare ok engine idle ..)

in fight your gyro "fuselage" will definitly be in horizontal position .. and if not you will be able to make small corrections ...

to achieve this in your case it will be super easy if you use the dom general shape

as you said you already know the tall tail size ..

then you know where your prop will be (vertically) , horizontally the prop will be 10 cm away from the tall taill .., then you have the mast (backward tilted on the dom) ..

Weight every component as accurately as possible and don't take anything else in account

Draw the back part of your dom on your computer ..

Place the rotor head at the same place then the dom

Then draw a line starting from the rotor head to the ground with a 8° angle ahead with respect to the vertical line passing at the center of the rotor head and finishing on the ground ..

you know that your center of mass will have to be located on this line ...

so now , place the passenger with his nostril on this 8° line (it will neutralize the passenger in terms of weight and ballance)

if you use a seat tanks place the passenger back on the 8° line

ok now you have 2/3 of your gyro .. weight all components of this tail/prop/engine/passenger/fuel tank (full) group and find out the center of mass

now draw the rest (pilot, fairing, front gear and wheel)

weigh this group components.

find out the center of mass of this group of components.

after this find out where you horizontal gyroplane center of mass IS (vertically 5cm above the thrust line and horizontally on the fuckin 8° line descending from the rotor head)

when I say fin out I mean take the coordinates of this center of mass from any chosen reference on the drawing (basically the mast) ... but it could be any horitotal point on your drawing place on the line passing from the passenger and engine center of mass ..

the coordinates will make it possible to calculate where you will have to horizontally place the center of mass of the fairing/ front gear/pilot group)

the resolve the equation :

( (mass of the front group x distance from reference) + (mass of the backwar group x distance from reference) ) / total mass of all components

before resolving the equation you will know :

- the mass (in kilos for example) of the front group (fairing, front landing gear, pilot),
- the mass of the backward group ( passenger, fuel tank, engine, prop , tall tail)
- the distance of the backward group center of mass from the Chosen reference)

resolving the equation you will find out the distance of the front group of components from the chosen reference (not from the backward group of components)

and magic will work ... your gyro will have all his components at the right place so that the center of mass place on the crossing of the famous 8° line and the horizontal line passing by the center of gravity of the passenger and engine center of mass ..

vertically the rotor being heavier then the landing gear, and engine/passenger/pilot placed on the same line .. mechalincally the gyro will be LTL

all of this will give you the horitontal placement of all elements so that your gyro pitches nose down 8° once hanging

as for the vertical placement of the cg .. it will be automaticall above the thrust line because the pilot / passenger / engine are aligned and because the rotor/rotor head are evier then the landing gear ...

at least this is what I think is working ... I am not and engineer.. just a lawer ..

of course, if you design things so that you can shift the horizontal front seat position a bit, will be easy to make small corrections so that your fuselage be perfectly horizontal in flight

there is also the possibility to shift the rotor head to make correction but remember that the horizotal distance from the rotor head to the man wheels must not be greather then 10 cm ..( the tricky part in my opinion)

last thing ... the back wheel ( under the tall tail) mus be placed so that the gyro can't nose up more the 13° (on the ground) it will prevent you from taking off behind the power curve

sorry for my horrible english

feel free to ask ... I will re write it in a better english


Last edited by Girodreamer on Sun Jul 10, 2022 2:22 am, edited 6 times in total.



Sat Jul 09, 2022 4:02 pm
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Wow! Gyro, what a treasure trove of hard learned lessons!
Fantastic!


Sat Jul 09, 2022 6:15 pm
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Thank You Giro!!! A lot of Great Info! Getting close to finishing a Long EZ then will be back into Gyros.


Sat Jul 09, 2022 7:40 pm
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thx Bro's it is nice to you

one thing to keep in mind when cloning the dom more accurately that what I did, is that Ernie's dom black top bar wher the rotor head is attached being long it will be impossible to attach the pre-rotator bendix in front or beind the rotor head

the bendix will have to be attached on the edge

this is why Ernie has chosen an hydraulic pre-rotator

so just plan to design the pre-rotator at the same time you will design the frame ...by far the pre-rotator is the most complicated part ot the gyro to design

If you use a flex shaft, make sure that the flex shaft is flexible enough not to limit your rotor tilting travel ...

I and still spending my week ends to finish an electric pre-rotator ... hahahaha

post us a picture of your Long EzE if you get a chance ... I love them ... making a gyro , even from scratch is nothing compared with making a rutan ..

don't hesitate to come back and tell us about your future gyro . it is always a pleasure to discuss about gyros, like in the past on the rotary ...


Sun Jul 10, 2022 1:45 am
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Countach wrote:
You did an excellent job on your machine. I posted here knowing the RWF would be of no help. I have a Single place Dominator, for starting the design. I will probably get a good side profile off the internet and import it into Autocad as a PDF then scale it up with known measurements. The tail is 68" tall, keel is 3" tall,


do you know the chord of the tandem tall tail ?

we are making moulds for a new type of tall tail and I am wondering if I we could use the same chord both for mono and twin seaters ?


Mon Jul 11, 2022 10:43 am
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Scaling it in CAD it looks to have a chord width of 15".


Mon Jul 11, 2022 7:21 pm
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Countach wrote:
Scaling it in CAD it looks to have a chord width of 15".


thx, I think both mono and tandem are using the same Chord but the tandem tail is taller

it is a good news for me because we are going to be able to make only one set of moulds both for the monos and the tandems ..

we are going to make tough moulds so that future builders cans fabricate their tall tail easily then spending months playing with aluminium or wood ....

I have noticed that fabrication of the tall tails were an issue for many newbies ..... along with pre-rotators ...


Tue Jul 12, 2022 3:47 am
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I will be doing a Rutan hot wired core with 2 layers of uni glass at plus to minus 30 degrees Spanwise. Uni directional fiberglass is incredibly stiff and light.


Tue Jul 12, 2022 1:59 pm
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yep for one tall tail it is wise tu use the rutan method, but the operator must be serious , weight the resin and squeedgee a lot on surface ... one of my mate did on using the rutan method and did a 11 kilos tall taill ...`

I think he put too many layers

on our side we want to make a tough mould for future builders, the mould would be stored in a RSA hagars (the RSA is the french home builder association)

when one will build a gyro, we will built the tall tail in 2 days


Wed Jul 13, 2022 2:13 am
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