Here is a list of all the postings Graham L has made in our forums. Click on a thread name to jump to the thread.
|Thread: Revolver Pusher type Autogyro trainer|
You will need your motor as far to the right as you can and even with this you will still need rudder offset to compensate for the spiral slipstream on the fin and rudder. This is a fact of life with most short boom pushers both model and full size. On my Revolver the offset is only needed above 15-20% throttle and so I have programmed a throttle rudder mix in the tx to remove the offset below this. Using a Spektrum DX8 the activated mix screen reads- throttle rudder, rate 0, rate 9,offset -15, trim act and programmed on gear switch 1 giving the option to switch the mix off. Everyone’s set up is a bit different and would need fine tuning for each model but it certainly significantly reduces the tail yaw when throttling right back. As Steve says you could just manually compensate on the sticks but feel that having paid out for modern radio I might as well use its benefits. If you don’t get on with it then at least you can switch the mix off.
Aim for a hang angle of around 16/17 degrees. That is a safe c of g at which it flies well. That is what it is on mine and I needed 5 clicks of up trim ( dx8) for it to fly level with the 5 degree backtilt. A heavier nose will need more backtilt on the head and it will not fly as well as it should as the blades will not be as efficient with a higher angle of attack
Using a 40 amp esc.. have not measured amp draw but motor and battery stay cool and I am easily getting 6.5 mins
Ps came from robotbirds under motors suppo/dys. It’s a dys
1am using a 3530. 10 1400 kv motor on a 9x 6 APCe prop. Loads of power and reasonable run time as it is flying normally at around half power.
Nice one Rich. Obviously no problem with the new 3 blade head. Seems to fly smoothly. May try one of the new plates and see how it compares with my set up
Steve . I am glad the head plates worked ok. Also The new undercarriage legs finish it off well.
As a matter of interest used a 1mm and 0.4mm plate together on the 2 blade atom with an anti strike plate and it flies ! Just need to increase the hang angle a bit as the blades are starting to stall on a downwind leg. Hopefully it should then fly as well as yours.
Tried the revolver with the10mm motor offset in the previous post which is as far across as you can go without significantly overlapping the side of the bulkhead ( mine overlaps 1mm). Still needs 5mm of left rudder to fly straight ( was 10mm before ) but at this there are no significant major trim changes when opening or closing the throttle which there was before with the motor at 5mm offset. . Will now leave at this as is comfortable to fly now at all throttle settings. May however experiment with props to see if this allows trim to be reduced further. . Given this is mostly the effect of spiral slipstream from the prop hitting the left hand side of the tailfin, by reducing or increasing the pitch of the prop ( currently using APCE9x6) then should be able to reduce the flow over the tail. However a larger pitch gives more thrust and less gives more speed so currently not sure which way to go.
However have now got a well behaved gyro with no surprises.
Look forward to hearing how you get on Steve.
Tried a throttle rudder mix to compensate for permanent rudder offset but made matters worse as I discovered that most of the rudder offset is caused by spiral slipstream from the prop hitting the fin on one side . This is unfortunately not linear with increase or decrease of throttle and proved to be a very scary short flight. Have now made a new motor plate from a lamination of 1.6mm and 1mm fibreglass plate ( to use my existing bulkhead mounting holes) epoxied together and have offset the motor 10 mm from the bulkhead centreline, which is just overlapping the fuselage side by approx. 1mm. Have not flown it yet due to high winds but hanging it by the head and steadily increasing throttle seems to show no undue nose swing.in either direction.with rudder centered. Will report back after testing. Malcolms plate looks good with even more adjustment and is well thought out.
Thanks Steve will post pics now after I get back from Winterton when I have time to sort it.
Sorry Steve but it wont let me paste the pictures into here.. If I open my last post I can see the picture but no one else can. Will have to seek advice.
My version finished.
Cracking job Steve - look forward to seeing it fly at Winterton. Formation flying with Rich could concentrate the mind !
Hi Steve - Hope all is OK.
Have used 10mm & 20mm blade end to bolthole on the Whippitts and 10mm spacing on the Atoms and all fly fine. In fact Malcolm sells a 0.8mm epoxy/glass blade ends set which is already predrilled for 10mm bolthole on the top plate. Unless Rich says otherwise, the main advantage I have found is that on the smaller plates is that in the event of a blade strike the blade seems less prone to damage from the head hub.
See you at Winterton
Thanks for the info Rich.
See you at Winterton
Excellent bit of flying in very windy conditions.
2 questions please as I am getting to the final stages of the build now . Did you stay with the 540mm blades ( and was that full length or tip to blade bolt ? Also was the initial motor position and offset OK or did you have to move it after the initial flights ?
Hope to have mine ready for Winterton
Glad the maiden went OK with only minor adjustment. Are you happy with the 540mm x 60mm blades or are you altering the length ? . Will try my usual head plate arrangement for this size rotor which is a 0.8mm and 0.5mm plate bolted together with the blade bolts Also use a 0.8mm round anti strike plate underneath which works well on my Mantis, Cooler and AC20 ( Steves version) . Hopefully this may help the pitch sensitivity.
Great scheme Rich and it will show up well in the air. AQt the risk of being controversial a true Brexit scheme !
Good luck with the maiden. Where did you end up with boom length ?
I think I am leaning towards a DYS 3530 10 1400kv on 3 cells and a 9x4.7 APC slowfly prop. Should achieve about 350 watts on 3 cells ( 430 on 4) and is a reasonable weight compared with its peers at 74 grams. Is also short so will help with C of G . Am using one of these in the Scout on 3s and a 10x4.7 and this will be probably a similar weight model all up. It is very powerful and quite efficient & gives a reasonable run time on a 2200 3s. Link to motor and specs below
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