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Old Apr 07, 2012, 02:02 PM
Registered User
Peterborough
Joined Feb 2009
167 Posts
Twin Blade RPG

Hi Guys,

At the meeting last week, I continued in my attepmts to fly an RPG with two blades rather than the std three. I did have some success, and completed several circuits, which is a big improvements on previous attempts.

I was pleased, but it didn't feel "right", especially when landing/flaring, when it just didn't have enough lift. I discussed this with the RPG Guru (Rich), and decided to remove the blade negative shims, to hopefully gain more lift at the expense of potential "spin up" problems.

I tried flying today without the shims today, and I now have the sweetest flying two blade RPG I could imagine. She flys quite a bit slower than my 3 blade, but just as well, and can now flare without any problem. As for spin up, well today was a very light wind, prob less than 10mph. I pulled the head back and just waited. The blades slowly span up with no intervention from me whatsover. It did take a while, but if they spin up in that wind, then there isn't an issue.

So I am dead chuffed, it has taken me over a year, and I think 4 sets (pairs) of blades, but finally I have a good 2 blade setup. The blades have a pine leading edge (from b&q) 8mm x 30mm, the size of the blades is 67mm x 690mm (2 5/8in x 27in). They are quite heavy with the pine, and come in at about 120gm covered. The shape is approx what the plan(rpg) show, but obviously scaled up, I didn't round the bottom of the leading edge by much. Hopefully there won't be any accidents between now and Winterton!.

Sorry, I didn't take my camera with me.

Cheers

Ian
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Old Apr 07, 2012, 02:56 PM
It was a GLITCH! Honestly!
SafeLandings's Avatar
Stourport on Severn ,Worcestershire, United Kingdom
Joined Dec 2007
4,901 Posts
Ian,
Congratulations, I knew you would get there in the end. You have been 100% dedicated to get 2 blades to work, looking forward to seeing it fly in the flesh
Bought myself a set of new scales today as my old ones were giving me odd readings.
As I was trying it out I went and dragged the crashed prototype RPG (crashed because of too much negative on its first outing after a total repair and re cover). My only remaining blade that I have left from all that experimenting weighs 73 grammes and that is with a tip weight, this blade flew really well hence why I have kept it.
One day I must rebuild 'good old faithful' its really not that bad.

Rich
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Old Apr 08, 2012, 04:03 AM
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Ricardo1500's Avatar
Wolverhampton, England
Joined Jun 2010
392 Posts
Ian

Well done on sorting those blades, its good to get there in the end.
As I mentioned to you at the meet up, I had thought that two of the Gemini blades ought to fly the RPG well, they are 760 x 70, so I'm going to knock up a fibreglass plate and give them a go!!

Will keep you posted

Cheers
Rich
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Old Apr 13, 2012, 09:10 AM
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Si_B's Avatar
United Kingdom, England, East Grinstead
Joined Nov 2007
117 Posts
Which Turnigy motor were people running their RPG's on. I saw a few at the meet, but forgot to write the numbers down. Going to order a few bits from HK, and get the motor for my rpg at the same time.

Cheers,
Simon
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Old Apr 13, 2012, 04:12 PM
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Ricardo1500's Avatar
Wolverhampton, England
Joined Jun 2010
392 Posts
Hi Simon

I use a Turnigy 3548....the one I had was 900kv, I think this is the one

http://www.hobbyking.com/hobbyking/s...dProduct=16231

I run mine on an APC 13.5x6 and its fine on either 3 or 4s but 4s suits mine better for weight up front

Cheers
Rich
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Old Apr 13, 2012, 07:22 PM
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Si_B's Avatar
United Kingdom, England, East Grinstead
Joined Nov 2007
117 Posts
I've got the same thing but a 1000 kv, might do the job.

Cheers,
Simon
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Old Apr 17, 2012, 10:42 AM
BigTradioman's Avatar
United Kingdom, Harpenden
Joined Oct 2009
403 Posts
I was running an Emax 2826/6 on 4s but it was running hot and pulling 60 plus amps on a 13 x8. After the meet I tried a 12 x6 and a 3s but in the end switched to an Emax GT2826/06 860kv on 4s with a APC 13 x 6.5 e prop. Its the GT that makes the difference.
http://www.giantcod.co.uk/epower-gt2...-p-406127.html
Huge difference in performance and is only pulling 45 amps at full throttle giving longer flights and more power. I am now building a second RPG from the a CNC kit and using the original plan NOT the Traplet modded plan. The only mods I will make are to go for an Alloy main cart and a steerable nose wheel. Any ideas for an off the shelf nose wheel are very welcome.
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Last edited by BigTradioman; Jul 02, 2012 at 01:05 PM.
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