RE: new Arf Boomerang 14lb thrust  
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RE: new Arf Boomerang 14lb thrust - 2/28/2005 8:37:29 AM   
john agnew


 

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From: glasgowScotland, UNITED KINGDOM
Status: offline 		Dave

The booms come with wire skids in case you touch them on landing / takeoff. There is still a bit of clearance with the model in a good takeoff attitude. At our field the runway drops away at the end of the tarmac and we tend to let turbine models fly straight off the end a bit like a carrier take off! When landing you can actually fly finals below the level of the runway and then pop up and drop the model onto the runway. sounds scary but it works! Got to finish the model may fly p.m. today if the weather holds up.

John Agnew

(in reply to rcguy!)
       Post #: 51

RE: new Arf Boomerang 14lb thrust - 2/28/2005 11:32:58 AM   
rcguy!



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From: Chesterland , OH, USA
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quote:

ORIGINAL: john agnew

Dave

The booms come with wire skids in case you touch them on landing / takeoff. There is still a bit of clearance with the model in a good takeoff attitude. At our field the runway drops away at the end of the tarmac and we tend to let turbine models fly straight off the end a bit like a carrier take off! When landing you can actually fly finals below the level of the runway and then pop up and drop the model onto the runway. sounds scary but it works! Got to finish the model may fly p.m. today if the weather holds up.

John Agnew


John,
Great! Alan seems to have thought of everything except hardware.

Dave

(in reply to john agnew)
       Post #: 52

RE: new Arf Boomerang 14lb thrust - 2/28/2005 12:57:12 PM   
john agnew


 

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Now for the bad news! To achieve the suggested CG of 150 mm back from the leading edge I will have to add 1 1/2 lbs of lead to the nose, this is not good! Alternatively by my calculation a 25 % CG would be 187.5mm back from the LE . The root chord is 450mm the tip 250mm giving an average of 350mm at mid span 25% 0f this is 87.5mm plus the difference between the mean chord and LE is 100mm giving 187.5mm.
This can be achieved with only12oz of lead giving a dry weight of 14lb 8oz with a full hopper tank.

Would any one like to confirm my CG calculation before the model is flown? I cetainly feel that 150mm is too conservative if my calcs. are correct.

To be fair to Allan he suggests moving the CG rearwards after initial flights without giving a specific figure.

John Agnew

(in reply to rcguy!)
       Post #: 53

RE: new Arf Boomerang 14lb thrust - 2/28/2005 1:56:52 PM   
rcguy!



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quote:

ORIGINAL: john agnew

Guys

Now for the bad news! To achieve the suggested CG of 150 mm back from the leading edge I will have to add 1 1/2 lbs of lead to the nose, this is not good! Alternatively by my calculation a 25 % CG would be 187.5mm back from the LE . The root chord is 450mm the tip 250mm giving an average of 350mm at mid span 25% 0f this is 87.5mm plus the difference between the mean chord and LE is 100mm giving 187.5mm.
This can be achieved with only12oz of lead giving a dry weight of 14lb 8oz with a full hopper tank.

Would any one like to confirm my CG calculation before the model is flown? I cetainly feel that 150mm is too conservative if my calcs. are correct.

To be fair to Allan he suggests moving the CG rearwards after initial flights without giving a specific figure.

John Agnew

Bummers! AND this is with a manual start W54? WOW! what kind of weight is needed for an auto start P60????
Alan tells me the plane in the video is box stock with retracts and weighs in at 14#. Maybe Alan can shed some light on this? How about some pictures of the insides of the plane shown on the video? I understand it is powered with a P60?

Dave Rigotti

(in reply to john agnew)
       Post #: 54

RE: new Arf Boomerang 14lb thrust - 2/28/2005 2:57:20 PM   
Ali


 

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From: Northamptonshire , UNITED KINGDOM
Status: offline 		Dave Hi,
The prototype model is indeed powered by a P-60. I know Alan did have some weight in there to get the CG forward but I certainly don't remember it anywhere near 1.5lbs. I also know that I l flew it with the weight in and it was too nose heavy so Alan removed some on subsequent flight which made handling a lot better for me. I am sorry that I don't have exact figures as I was just flying Alan's model.
Normally Alan would be straight on here to help but I know he is now in the US clearing the us delivery of the intro's and prepping for Florida Jets. I will see him On Thursday in Florida so if he hasn't answered by then, which I am sure he will I will tell him to get on here and help you guys out.

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(in reply to rcguy!)
       Post #: 55

RE: new Arf Boomerang 14lb thrust - 2/28/2005 3:22:20 PM   
john agnew


 

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The model is now 100% complete. Final weight 14lbs 10oz CG at 175mm behind LE, 12oz lead right up in nose (In noseleg compartment)

You may not need as much noseweight with a P60 as it has a heavier ecu battery than the manual start Wren 54 and you can also mount the solenoids and ecu at the front. My model has a 6 ounce Graupner hopper which is always full mounted right behind F1 under the radio tray.
You can see this in the gear install photos. I still don't believe this model can be built at 14lbs unless you use very light servos.

Sorry no flying today as it's crap weather here, hope to get out sometime thia week. A picture of the finished model and one with my Savex size L39 for comparison. I don't know why Allan used to call this the Baby Boomerang as it ain't no baby!
This is a large model and should be vey easy to see in the air.

Any more queries regarding the model don't hesitate to ask.

John Agnew

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       Post #: 56

RE: new Arf Boomerang 14lb thrust - 2/28/2005 4:19:40 PM   
Dave03B


 

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From: Bournemouth, UNITED KINGDOM
Status: offline 		Great looking model....Didn't realise that it was that comparable in size to the Savex L39! Intro looks to be a great little package, I'd like to hear how well it goes with a 44.

Dave

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RE: new Arf Boomerang 14lb thrust - 2/28/2005 4:47:14 PM   
john agnew


 

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I think my photo is slightly misleading. It was meant too show how much bigger than the L39 the Intro is!

I did think of putting my 44 into the Intro. I think it would be possible to get the weight down to about 12lbs dry if you did this.

The problem with the CG is the long tail moment which probably makes the model so nice to fly. With a 44 you could use light servos in the tail and reduce the amount of weight required up front.

I still think the ideal model size for a trainer for the 44 would be about 65" span weight 9/10lbs, mini servos and light retracts or fixed gear.

Unless someone comes up with a suitable model I may build my own.

John Agnew

(in reply to Dave03B)
       Post #: 58

RE: new Arf Boomerang 14lb thrust - 2/28/2005 4:52:08 PM   
Dave03B


 

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quote:

ORIGINAL: john agnew
I think my photo is slightly misleading. It was meant too show how much bigger than the L39 the Intro is!




If you want to knock up a trainer for the MW44 that's cool looking. I'll 'av one


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       Post #: 59

RE: new Arf Boomerang 14lb thrust - 2/28/2005 4:58:54 PM   
john agnew


 

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This is my IAD Serpent which flew great at 17lbs with a Ram 500. I put my 44 in it when I was waiting for my L39. Took some battreies etc out and got the weight down to 12lbs or so. It flew very well with limitations on the vertical. A 65" version of it would be perfect for the 44.

Now tell me which is the beter lookiong model?

John Agnew

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RE: new Arf Boomerang 14lb thrust - 2/28/2005 5:05:40 PM   
Dave03B


 

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Status: offline 		I can't answer that! I look forward to seeing your flight report and video?

Cheers
Dave

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RE: new Arf Boomerang 14lb thrust - 2/28/2005 5:24:08 PM   
turn and burn


 

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From: flintshire, UNITED KINGDOM
Status: offline 		i no its of topic but my mate flys the iad serpent with a kj66 in it 3litters of fuel it a nice model

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       Post #: 62

RE: new Arf Boomerang 14lb thrust - 2/28/2005 8:11:34 PM