A poser from Grapher

My curiosity has been kindled by the piece in photo gallery(February covering Brian Collins' E3D. In particular the comment saying that the 2820/10 will swing a 13x10 propeller without a gearbox. I have two of these fine motors and though I do not dispute that it WILL swing such a propeller I do wonder whether Brian has measured the current being drawn. That motor has a specification which states that its efficient range is 25 to 30 Amps with a maximum loading of 40 Amps for 60 seconds i.e. 1 minute.

I have measured those parameters using my Astro Whatts meter on precisely the same power pack, namely 10xCP1700. I keep records of the statistics for full throttle when the battery is freshly charged (approximates to what is taking place at take off and first climb) followed by the same readings at a steady 50/60% throttle. For a prop of 11 x 7 (all props are APC electric) full throttle gives 38Amps/414Watts which is well out of the "efficient band";"half throttle" gives about 9 Amps and 110Watts. Similar figures for an 11 x 5.5 prop on full throttle - 36Amps, 380 Watts. In flight the motor is encountering a more hospitable environment because it isn't tethered so it is safe to assume these figures will decline in flight. From that I figure that the ideal prop for the 2820/10 is the 11 x 5.5

I would be interested to know whether Brian has made similar measurements? Whilst these comments may be controversial - though I hope not - I am stimulated by a fear that Brian's motor may be ove- taxed despite the higher torque (which is what enables the outrunners to swing bigger props without gearboxes). I am as certain as I can be that a 13x10 prop will on fresh batteries be taking his current draw well into the 40Amp decade and if as I guess, he is using a 40A ESC, probably a 40-3ph Jeti derivative, then he will likely be risking cooking that too.

You know that I wouldn't dream of asserting that I am any kind of an expert in this field. However, my scientific training insists on measuring critical parameters and I have certainly learned how difficult it is to judge what is the best propeller with absolutely no instruments for measuring such paramaters. Maybe Brian will be able to demonstrate that my figures are contradicted by some of his own? We may both learn from that!

• A nice one for you electric techies - and I reckon that Grapher is fast becoming an expert, despite his genuine modesty!
  

Ron Paxton commented on the reluctance of some UK clubs to publish members' lists on their web sites. Malcolm says:

I heartily agree about member lists. I'm a member of two clubs in the USA both of which publish their members' names, addresses, phone/FAX/email, good time to contact. In that highly litigious country, if they don't mind ........ !

Terry Gregory mentioned flying problems with his Easy Pidgeon. Malcolm comments:

If that's the ARF electric powered glider, I share one with my son Simon and grandson Alex. It flies great and has done for about the 2 - 3 years we've had it. We bought it because another flyer at Sutton Park had one and it just looked too good to be true.

So, are the incidences and the CG OK? Checked for warps? Are you sure the motor has downthrust in relation to the flying surfaces - (have to ask - OK )? You don't say how it glides with power off - or how it flies on reduced power? Have you checked the surfaces with power on AND the model in your hand, to be sure there isn't something from the motor affecting the radio? (Beware of the prop when you're doing this !) I don't have it here in Bangkok with me to check any of these points as it lives in UK with Simon and Alex.

Has Lawrence Cragg found the answer?

I think I have mentioned problems with a Great Planes Extra (60) which has given me lots of exercise going to fetch it. The model has a Saito .91 four stroke engine mounted side ways and that engine will idle forever. However, every time the wheels touch the ground on landing, the engine quits - hence the aforementioned exercise. I tried everything I could think of to cure it of this problem including mounting a throttle servo on the firewall to shorten the linkage between the servo and the throttle. Nothing worked so I retired the model before I jumped on it.

I don't really know what causes this infuriating behaviour but, during this build season I had another look at it and noticed that the side mounted engine brought the carburetor needle valve above the fuel tank. Since I have tried every trick in the book to cure it without success, I am reduced to clutching at straws. The observation that the needle valve is above the tank is one such straw. It is possible that the landing bump (no matter how gentle!) is just enough to induce a slightly negative pressure in the fuel line - enough to momentarily starve the engine of fuel and effectively kill it. I have now fitted a small header tank. Hopefully, a landing bump with a header tank will induce a slight increase in pressure. We shall see in the spring.

Another problem with this model is weak landing gear. (No, my landings are not all that bad!) I hope I have cured this problem with doubled landing gear rails.

All I need now is for spring to get sprung so that I can find out if I have cured the beast. I'll let you know.

• An interesting little problem - anybody else got any suggestions on its cause and cure, I wonder?

Bill Horoszko wants a beefy bender

I just reviewed your latest, greatest ModelFlight web site - very impressive to say the least.

I was wondering where one might get hold of the wire bender shown in the Building from Plans article by Chris Hardie. It looks rock solid and much easier to use than anything I've seen to date.

Thanks for keeping me on your list, and by the way I'm in the process of having the last "large scale" B-17 kit shipped from the UK to the USA . . . it's one of the one's made for the movie Memphis Belle and you could see two of the others in the Le Ferte 2000 video.

• You're quite right, Bill, Chris's wire bender IS rock solid and a very nice bit of gear. It is a product line of MFA Como Drills here in the UK, contact details as follows. Address: MFA Como Drills, The Mill, Mill Lane, Worth, Deal, Kent, CT14 0PA, England;Tel. (44) 01304 612132; Fax. 01304 614696; e-mail enquiries@comodrills.com

Last month's 'clubhouse' reported the death of William (Bill) Bennett, founder and sponsor of the Tournament of Champions, and posed the question as to whether this major RC event would continue.

Dave Manley comments:

I've heard through some IMAC members (not high-placed folks, just members) that the TOC dream died along with William. Word is that participants are trying to find other sponsorship. They do not want the event to die. It may take some time, but they are going to pursue new funding sources.

Malcolm Logan comments further on TOC

Himself a good source of reliable information, Malcolm has heard from equally reliable sources that Mrs. Bennett has decided not to continue the Tournament. Looks like this is an end of an
era, they say.

One person closely associated with the organisation of the contest has worked out Mr. Bennett has donated over $9m towards the TOC, Scale aerobatics and RC aviation in general. "All good things must come to an end, but please think of where our industry would be without Mr. Bennett's contributions," he says.

Martin Williams - re-inspired!

Thanks for writing the artical on electric flight. I have been trying for years to come to a good combination of cost against power and was about to give up and stick to the IC. Every time I have smashed up an electric model it has normally been on the take off due to the lack of power. I built the new Robbe electric spitfire which took two weeks to build and three seconds flying time before total destruction.

Every time this happens, I pull my old Limbo Dancer out of the cubboard, fire up the motor, and off she goes so I know it's not all me.

I had many hours of fun with a (believe it or not) Mulitplex Twin Star but I always felt the rate of climb left a bit to be desired.

I have made my mind up now, after reading your article I am going to replace the STD 400 motors with a pair of Brushless equivalent.

Overlander.co.uk do a kit for just over £200 including the controller, so cross your fingers for me and let's see if the boring electric Twin star, can hang on to its props.

Kind regards.

• Hi Martin, and welcome to ModelFlight! I guess you were inspired by Grapher's enthusiastic comments on brushless motors on February air space. All the best with the modification - do let us know how it goes!

Trevor Sonnenberg - broken link

Hi Reg,
It's good to see your magazine again and I'm pleased to see you had a good Christmas and new year!

Could you please forward the correct e-mail address for the RCM&E PLAN SERVICE ..the link is not correct.

Regards
Trevor Sonnenberg

• Thanks for your e-mail, Trevor. I note that the link on my site shows modelfying.so.uk instead of .co - sorry about that.
  
  Anyway, I've done a bit of surfing and think that RCM&E may have also changed a thing or two. The plans service is now part of their Modelshop pages. The following link takes you direct to the plans section, from where you can choose from various categories of plane, and there's also a search engine that can be used for specific plans.
  
  Here's the link
  
  http://www.nexusonline.com/pages/nexusdirect.ngi
  
  Happy browsing, and thanks for the query - I like my site to work!

Graham McAllister surfaces - from Wisconsin, and with a wife!

It's been awhile since I wrote as rather a lot has been happening in mylife.... just little stuff like emigrating to the USA and re-marrying! Well all is going well on those counts, I am settling in nicely and aclimatising to this Wisconsin winter, although it is a very mild one I am assured! Even so this is the land of ice fishing and driving trucks across the lakes. I love it! And Jan too of course!

Modelling wise I am setting up my workshop in the basement... and 'Graham McAllister Designs..." will be up and running again as soon as the US government allows me to work... (work permit takes about 5 months in my situation). I am going to concentrate on the smaller designs and expand the range there, the SkyBug has been by far my most biggest seller, with the Ironic.2 close behind.

The GMD web site at www.mcallisterdesigns.com will be kept up to date through this time, the Basic Guide to Successful Electric Flight is still there for "free" and a "log book" email is available too. Very soon there will be an extensive photo page covering the building of the SkyBug, SkyHawk and TwinHawk as an extension of my building instructions. Please keep visiting and signing my guest book!

And can I say "hi" and "thank you" to all of my excellent customers from the last few years, many of whom have become friends too. Hi to all the Buggeteers..!

The Ironic, SkyBug, SkyHawk, TwinHawk [pictured right with Graham] and 1912 Filey Flier are now available in the UK from Direct Model Products, they will be manufacturing the 'Park Flyers' and continuing with the supply of electrics for the UK market. So please visit them at www.directmodels.bravepages.com and give them your support. Or if you are anywhere near the USA my mail order service will be running soon (gov. permitting!).

I will soon be joining the local club here, the Sheboygan SHARKS, friendly bunch of guys they are! I'll write us up for your club spot, Reg, when the weather improves . . . keep up the international flavour. Nice job you are doing as always.... I am reading it all the more now that I am far away . . .

Take care all you guys... have fun, that's why we are in this hobby.

Graham McAllister

• It was a real joy to hear from your Graham. Warmest congratulations on your marriage, and all the best to you and Jan. Thanks for all your interesting news and promise of things to come.

Pat Tritle

Progress with the 'Pusher'
I have been flying and "tweeking" the Curtiss Pusher. The big breakthrough came today by changing the prop from an 11-7 APC Slow Fly to an 11-7 APC-E, and going from a 800AR 7cell ni-cad to an 1100 8 cell Ni-mh. With the CG at 38% it's an entirely different animal. I really liked flying it all along, but now it flies GREAT! I didn't notice any difference in speed, but everything about the model's flying qualities are more positive, and the duration DOUBLED. What a difference a prop can make!

• The design and building of Pat's beautiful Curtiss Pusher was fully documented on work in progress #67 and #68 and is well worth a look!

Ian Ankers requests a link

I hope you can assist me, I run an electric flight specalist store in the UK called E-Flight and I was hoping you would be so kind as to add a link to us on your pages. I have often used your site and found it most useful!

The site address is http://www.e-flight.co.uk and I'd appreciate your comments since you run a website yourself.

• Happy to oblige, Ian - it's always good to broaden the choice for all of us eager to spend our money! Take a preview of Ian's site on site seeing.

- and so does Alex Lewin

Hi Reg,

Chingford Model Flying Club now has an official website:www.chingfordmfc.com.

I came across your website which looks to be a geat online resource and I was hoping to get a link to our club's website from your Clubs & Associations page. I have already linked to your homepage from our site.

Best regards,

Alex Lewin.

• Delighted to add yet another club, alex, and many thanks for the link you've already given to ModelFlight. Read about Alex's club and website on club scene.

If you write to me at ModelFlight, you will automatically be added to my mailing list to receive a brief reminder each time a new issue goes up on the Web, unless you tell me otherwise. If you are making contact for the first time, please tell me what country of the world you are from - I would hate to miss a chance to add another flag to my collection!

I assume that you are happy for me to publish anything you say in your correspondence, again unless you state otherwise.