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Revolver Pusher type Autogyro trainer

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Richard Harris18/08/2019 09:47:32
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2051 forum posts
1890 photos

Chris,

Can't say I have ever noticed a visual issue, that said, I do fly my autogyros at close quarters 90% of the time.

Removing horizontal tails opens up the flight envelope making the autogyro cleaner in higher winds, which seems to be a growing trend over here at the moment! It removes the pitching that can be caused by upward draughts acting on the tail end.

I remember a conversation with the late Wing Commander Ken Wallis where he had just demonstrated 'Zeus' in near 30mph winds doing his usual 'hands off' flying. After he had landed I asked him what it felt like in the wind, his answer was simply 'what wind'! He then went on to explain in great detail the effects of horizontal stabilzers in windy conditions and how his 'fin only' machines were unaffected, it was quite interesting.

You ought to try converting one of yours, just to see?

Rich

Big T18/08/2019 10:02:10
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215 forum posts
202 photos

Rich, I thought that on pushers the horizontal stab was needed to counteract the prop wash. Also it acts as a mount for the extra vertical stabs that prevent Newton’s 3rd law yaw?

Richard Harris18/08/2019 10:31:39
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2051 forum posts
1890 photos

Tim,

Horizontal Stabs act as pitch dampeners giving the ability to stabilize an autogyro with a thrust line offset to the CG (vertically) as does the drag from the rotor disc. As long as the thrust line is close to the CG in height the horizontal stab can be removed.

Yaw is effected by the motor torque and prop wash, it can be increased or decreased by either moving the motor/ rotor spindle to the side or the position of the vertical fin and its area from the prop. It can also be controlled via mixing of radio inputs at different throttle settings.

The stab does make a good mounting point for the outer fins, these were added to give about 25% of added extra vertical area out in unblocked air for added stability when the motor is off.

As I am removing this the extra vertical area it will be added to the standard fin.

Rich

David Holland 219/08/2019 16:50:57
189 forum posts
25 photos

i have finished my Ken Wallis version of the Revolver and am really pleased with it. Great fun building something different , never having tried an autogyro before. I took it to the field yesterday with the intention of doing a few trimming hops but the wind was so strong that the rotor spun up and it blew backwards and I didn't have the bottle to open the throttle (cor, that rhymes). I'm going to try again tomorrow if the weather cooperates. Richard, did I imagine it or did you say you fly Mode 1 and will be at the RCM&E Fly-in at Buckminster, and if so would you consider maidening it for me if I chicken out tomorrow?

 

David

Edited By David Holland 2 on 19/08/2019 17:00:12

Richard Harris20/08/2019 09:36:42
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2051 forum posts
1890 photos

David,

I really like what you have done with your Revolver smile d

Regarding the Fly In I am hoping to go but nothing is set in stone at the moment, I do fly mode 1 and would be more than happy to maiden and trim out your Revolver.

Not sure if you go or not but I'm off to the Nationals this coming weekend, I will slip mine into the caravan in hope that I can get some stick time on the evening RC line. If you do happen to be going then bring it along?

Rich

Chris Dowell20/08/2019 09:51:52
100 forum posts
47 photos

David

Oh yes ..that is a great looking version.

Rich

Ok I will remove the stab from my Mantis ….What could go wrongdont know wink

Chris...

David Holland 220/08/2019 10:23:47
189 forum posts
25 photos

Oooh, thank you, kind sirs! Richard, I am going to the Nats on Saturday and would love to take you up on your kind offer. Perhaps you could PM me with a contact number and we could meet up in the evening?

David

Richard Harris20/08/2019 16:35:13
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2051 forum posts
1890 photos

David,

Sounds like a plan, PM sent. Weather is looking really good for the weekend smile

Rich

David Holland 220/08/2019 17:10:12
189 forum posts
25 photos

PM received, Richard, and I have replied. I can't believe the forecast, decent weather for the Nats, unheard off. Didn't try flying it today, still a bit too breezy for an attempt at a maiden. See you Saturday.

David

Cuban821/08/2019 09:26:23
2641 forum posts
13 photos

Don't know if many of you chaps have seen this great bit of film from 1931 (love the haircut - quite modern) what's interesting is how the aerofoil of the machines blades looks to be almost symetrical  and how much more in the way of having a higher aspect ration compared to our models. The machine in the film also shows a pronounced coning angle of the blade disc - not so noticeable with models? Scale effects coming into play?

Edited By Cuban8 on 21/08/2019 09:35:35

Richard Harris26/08/2019 21:14:39
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2051 forum posts
1890 photos

It was a pleasure meeting Dave with his Nellie Revolver last weekend st the Nationals.

No issues were encountered, all that was required was a few clicks of rudder trim. Dave was soon doing circuits for the first time and I think he was pleased with his results.

Unfortunately I only had my phone on me but I did grab a few photos and a minutes worth of footage.

 

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Edited By Richard Harris on 26/08/2019 21:15:10

Edited By Richard Harris on 26/08/2019 21:15:29

David Holland 226/08/2019 21:35:17
189 forum posts
25 photos

Richard, to say I was pleased is a bit of an understatement! To see it flying and to have a couple of flights myself was a real buzz. I can't thank you enough for designing and developing the Revolver and for sharing it with us through the forum and the magazine. Thank you also for taking the time on Saturday to check Nellie out and trim it for me. To anyone hesitating about building a Revolver, go on, take the plunge. You'll love it. It is a little different to flying a fixed wing aircraft but not that difficult (can't be, I flew mine and landed it in one piece) and is quite addictive. I'm hoping for a couple more flights tomorrow.

It was a great pleasure to meet you, Richard, and thanks again for the help and encouragement.

Regards,

David

David Holland 228/08/2019 19:54:41
189 forum posts
25 photos

Richard, sorry to be a pain but a bit of advice, please. I tried to fly "Nellie" again yesterday and could not get the rotor up to speed. There was very little wind but our patch is quite long and no amount of taxiing would get the rpm sufficient to take off. After Saturday I found one of the servo arms had cracked (probably that last "landing" and replaced them with ones a little shorter. The blades just clear the rudder at full back stick so I don't think I'm short of movement. Any ideas?

Regards,

David

Richard Harris28/08/2019 21:08:32
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2051 forum posts
1890 photos

David,

If your blades are close to the fin when tilted right back then that is more than enough for them to spin up with a slow taxi into wind.

On Saturday they did seem to take a little longer to get to full RPM, once in the air they were fine with lots of lift. What I would do is add extra shim to each blade, only thin shims, I find that masking tape works ok.

Try that and see if this improves spin up? you will find that by adding extra shim you may need to add a click of extra rearward tilt.

You could also try hand launching? I know Chris from down under swears by this, I'm sure he made a video of how he does it too.

Talking of videos here is the small amount of footage I captured of your first flight with an autogyro including the landing.

Rich

Mike Sargent 129/08/2019 11:17:48
2 forum posts

When designing an Autogyro what factors are taken into consideration when the main blades are planned.

Clearly the size and weight of the planned aircraft but how is the blade cord, length and section determined?

Mike

Richard Harris30/08/2019 15:40:46
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2051 forum posts
1890 photos

Hi Mike,

With a 3 blade rotor system I aim for an aspect ratio of around 10:1, length is determined by the weight of the model and whether I want it to fly lightly loaded or not, this aspect ratio increases with 2 blades with a like for like model as you need an increase in blade length.

When I first started messing most were using a Clarke Y aerofoil or a similar section with a chamfered lower TE. Through experimentation (and a bit of luck) I came up with a section that has a sharp LE, this is what I use on pretty much all my models from about 2010. They have a good spin up, plenty of lift and above all are easy to make.

Rich

Trevor31/08/2019 08:32:22
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365 forum posts
52 photos

I have a self-imposed rule that winter builds can't be started until September. I just may have jumped the gun a little bit on this one:img_2436.jpg

But then, cutting out a few parts doesn't really count as building, does it? angel

Trevor

Richard Harris31/08/2019 21:15:01
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2051 forum posts
1890 photos

Resistance is futile Trevor, you will have that together before the winter is set in!

Here is where I'm at with my second Revolver, fin only with a cranked boom giving me room to lower the motor.

The blue canopy may not be fitted as I'm awaiting a vac formed version from SARIK hobbies off my plug.

 

20190831_145635.jpg

Edited By Richard Harris on 31/08/2019 21:17:07

Trevor01/09/2019 07:54:23
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365 forum posts
52 photos

It's amazing how that cranked boom changes the appearance. Of course if you're leaving out the horizontal stab then the plan view will be very different too.

I have a canopy on order from Sarik. Having failed to find a suitable pilot, I'm contemplating just painting (or at least tinting) the canopy and forgetting about the interior. Motor and ESC are also on order and hopefully, with a bit of improvisation, most of the other bits will be from stock.

And, to complete the confession, I did get the glue pot out yesterday!

Trevor

David Holland 201/09/2019 21:12:41
189 forum posts
25 photos

Thanks, Richard and applogies for the delay, been away playing trains. Will try an extra shim, I'm sure you mentioned that at the NATs. Enjoyed the video.

Regards,

David

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