AVRO Arrow EDF design -- kicking around some ideas - RC Groups
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May 29, 2002, 12:51 PM
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byrocat's Avatar

AVRO Arrow EDF design -- kicking around some ideas

I guess that if you scratch any Canadian jet-jock, you'll find them bleeding Arrow information.

I thought that I'd fire a few ideas for a design I've been piddling around with and see if they're workable or not. Please feel free to comment or vent as needed...

single versus twin engine -- the scale fuselage is a 1x2 height-width ratio. A single engine version will have a lot of empty space to either side fo teh fan unit. However, a twin engine is going to be a bit easier to make ducting and everything else for.

Question: Can a single set of batteries and ESC be used to drive two fan units, and should the fan motors be parallel or series connections?

The core section of the fuselage that takes all the major items like batteries, wings and such is pretty well self-contained and can be constructed as a box.

Question: should I use a central spine to hold everything in place with the fuselage sides there for shape or concentrate on the box shape with formers taking the streses and transferring them to the fuselage walls?

You've probably guess that the nose section is going to be an aerodynamic shape along for the ride and to balance everything.

Question: can the nose be straight foam sanded to shape or can a paper-mache/brown-paper nosecone be used? Also, what are the wight considerations for each.

Last Question: Been looking around at the catapult-launch systems and trying to figure out how the other aircraft are set up for hooks? No, not the location, but how they're tied into the structure of the aircraft so the acceleration doesn't rip them out.

Thanks all!
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May 29, 2002, 01:14 PM
RPV builder & operator
Pierre Audette's Avatar
Welcome aboard byrocat. I've been toying with the idea for some time, but only got as far as trying a very crude prop job flat plate delta.

For an EDF, it would have to big pretty big to keep it to scale. The other option would be to make it a pusher prop, like the Wattage Mirage.

Another nice jet done as a pusher I came across recently is the Rafale.
May 29, 2002, 04:18 PM
Registered User
Hello ByroCat -

If you use a single ESC and battery pack, the key condition is going to be how many amps you are drawing from the motors/fans. You can control this to some extent by parallel or series wiring of the motors but then you end up with either cells that are seeing high amps or lots of cells and the weight of them. What are you planning on for motors and fans - MicroFan, MiniFan or MidiFan and what motors? That'll define the appropriate answer/answers to your question. As an example, a pair of MiniFans at 35 amps wired in parallel will mean the cells seeing 70 amps - not good for them - and an appropriately sized larger esc. In series, that means twice as many cells but the cells will see 35 amps, much easier on the little guys.

As Kevin Cox states in the Big Bug thread, a twin sounds cool. Kevin and some of the others who have flown twins can give you "real" experience from their installations.

Down the road I want to do a F2H Banshee and an RA-5C Vigilante and in both cases I've been planning on two separate power packages (10 to 12 cells & either MiniFans or Flash fans) The only unanswered question to me is whether there are problems in synchronizing the rpms of the two fans/set ups.

Fly Fast! Mark
May 29, 2002, 04:20 PM
dorysch1's Avatar
It could be done I built my own tutor jet I made the fuselage out of fiberglass buy making one out of foam then glassing it and the wings are foam core the Arrow could also be done midi size would be neat!
May 30, 2002, 07:01 AM
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hi byrocat, i too have been toying with this idea of a twin in the avro, i was designing mine around 2 mf-480s with a BL setup, all i have to do is a little more homework on the batt. count and esc, as far as your ? on the catapult hook for the launcher, what i did was used a 2in. 4-40 bolt and cut the head off, bend it at about a 20 degree angle, i have mine screwed in to the fuse and backed up by a nut( actualy 2 nuts, 1 in the plane and 1 flying it ha ha) heres a pic
just make sure you have a ply capped balsa block between two formers, mine works flawlessly

my avro would have a 35in.ws 50in. long 2 mf-480s 2 bl motors and run on 20 cp-1300 with a projected weight of 50 to 55 oz. the batts. them self would weigh almost 30oz. so thats only leaving me 20-25oz. for airframe,radio,motors but i think it can be done!!
Last edited by ESB; May 30, 2002 at 07:15 AM.
May 30, 2002, 07:02 AM
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May 30, 2002, 07:07 AM
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pic 3 jet and launcher

May 30, 2002, 11:15 AM
dorysch1's Avatar
A friend made this static model
May 30, 2002, 09:36 PM
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gbruce's Avatar
Hey Dave

the model itself looks GREAT...but what's up with that landing gear??? Looks to be about twice as long as it should be...

May 31, 2002, 09:22 AM
thulizulu's Avatar

donīt worry about the sync of rpm. They will be forced to be running at same rpm by physical law Threre will only be problems if running them on seperate packs and controllers.
Just think of your X-mas tree and/or street lights.
You mentioned the Vigilante, well this is just a dream of a ship.
I think of it every now and then.
Have you got a source of getting a view of the fuselageīs cross sections?

Jun 03, 2002, 10:20 AM
dorysch1's Avatar
I'm not too sure why anyone would build something that doesn't fly anyway hehehehehehehe but that is his hobby it looks nice next to the bugs though
Jun 03, 2002, 02:32 PM
It wasn't me...
DanSavage's Avatar
Originally posted by Mark Nankivil
The only unanswered question to me is whether there are problems in synchronizing the rpms of the two fans/set ups.
Hi Mark,

As you're probably aware, I'm running two fans/BL motors/BL ESC's in the Flanker that are wired in parallel, drawing off a single battery pack. So far, syncronization (or lack of it) hasn't been a problem. At full power, the two fans are a bit out of sync, but it doesn't seem to have an effect on the take-off or climb out. Once in flight, I reduce the power to save batteries and the fans sync up so well that it sounds like a single fan is running.

The only thing I could call a problem I've found with running two ESC's is that one hits the LVC before the other. I get around this by timing the run time while in flight and making sure that I'm on the ground before this occurs.

In the B-57, we're running two fans/motors and a single ESC wired in series, drawing off a single battery pack. Even in series, they're still slightly out of sync.

Given the fact that the B-57 is very yaw-prone with the long wing, short fuselage and wide-spaced engine nacelles, this hasn't really been a problem.

So, if I were building something like the Arrow with closely spaced fans, I wouldn't give syncronization another thought. Just build it and fly it. With pics & video, of course

Jun 03, 2002, 05:15 PM
Registered User
Greetings All -

Dan - thanks for the feedback. Not going to worry about it then and just need to build it

Thulizulu - thanks too for the feedback. I do have some North American Aviation drawings for the RA-5C and for the A-5A Vigilantes with fuselage cross sections. If you are interested in a copy of those drawings, contact me direct at nankivil@telocity.com
and we'll figure out how to get them to you.

Fly Fast! Mark
Jun 05, 2002, 12:50 AM
knight of Ni's Avatar
Hi byrocat
Well I'm assuming you already have scale documentation on the Arrow. If not I've got some very detailed cross sections that I could scan for you. BTW it better be RL 206! Now if someone just did a turbine version........
Jun 07, 2002, 01:09 PM
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byrocat's Avatar
Originally posted by knight of Ni
Hi byrocat
Well I'm assuming you already have scale documentation on the Arrow. If not I've got some very detailed cross sections that I could scan for you. BTW it better be RL 206! Now if someone just did a turbine version........
I'm not going to say that I have documentation coming out of my ears, but I've got the basic Arrow books: the one by the "Arrowheads", and the "Arrow Scrapbook" that came out a few years ago. Also have the CAHS 3-view, the one that came with the vacuumform kit about twenty years ago (same artist did both), and a copy of the actual Arrow blueprint that shows not only the sections but also the surface throws and c/g range.

BTW, if anyone is looking for arrow books, there are about a half-dozen ones at Chapters/Indigo Books here in the Toronto region. Range from the historical theories to the social impact and the new ones by the Arrow Alliance (raising moneys for the construction of a one-off flying replica.)

EBay is also a good source for Arrow items. Even a guy who's flogging catapult glider kits of the Arrow.

Anyway, have to ring off... lunch is over and tiem to get back to work....

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