Can-Doo - the new design from Nigel Hawes

[Colin Leighfield]

Hope you're better now Nigel, sounds nasty.

[Bob Cotsford]

Posted by Nigel Hawes on 29/11/2013 22:12:21

........but I had an accident, breaking my thumb and back, ..........

Nigel Hawes.

Nothing serious then Nigel I hope there's no lasting effects!

Can-doo - is the fan version still in the pipeline? I have a 64mm fan in need of a home.

[Nigel Hawes]

No nothing serious, just 5 lumbar vertebrae transverse processes and my right scaphoid and metacarpophalangeal joint! (Oh yes, he's had his alphabet soup this morning!

I'm fine now but it did disrupt many things, the CAN-DOO being one of them. So the plan was published about 14 months later than planned as we had no flying shots, and my broken thumb made flying pretty difficult! This also explains why my column contained very few flying shots during the corresponding year too.

Irtonically I'd just flown the EDF prototype before my accident and was working on an effective method of attaching an EDF unit to a flat sheet wing securely, but with scope for adjustment of the thrustline, something that required experimentation with the pusher version.

The prototype had a tiny 55mm unit attached any way I could manage it just to see if it would fly (I think chewing gum, cable ties and duct tape all played a part here!) but the thrustline was wrong, so when I get time to sit down and consider a proper mounting method, I will follow the plan up with the EDF details.

The biggest problem is that even the weight of a 55mm unit required the 2200 ma/h 3s Li-Po to be right at the front of the battery area, so a 64mm unit would require a heavier Li-Po still small enough to fit the confines of the fuselage! But it's a challenge and I hope to have another look after I've caught up with everything else!

The model flies very well indeed but as described in the text it does require a little thought with the set-up, and hopefully this thread will pool everyone's findings and help other builders achieve success with theirs.

Nigel Hawes.

[Colin Leighfield]

Nothing serious Nigel? Ouch! Glad you're better anyway. I've haven't done a canard since the days when I experimented with every layout you can imagine with chuck-gliders, but I remember that they can fly very well, with a flat stable glide. The same was also true of the tandem wing layout. An X-Wing variation of that also works well and looks good.

I'm keen to do this and add it to the Fizza and Tucano, but it has to go into the post-Christmas queue. Things are slowed down because of extra chores while my wife recovers from surgery, but I'll get there. I must finish the Seafang and a couple of solid days will do that, but I haven't been able to get in the shed for a week. (Sheer frustration)! but I might have a chance over this weekend,

[Nigel Hawes]

Colin -

I hope your wife makes a speedy recovery, I empathise fully.

The CAN-DOO is my first attempt at a canard, and was an eye-opener when it came to set-up as I hadn't a clue! But all the Burt Rutan full-size canards are highly acclaimed so there's obviously something quite special in this layout.

I quite fancy a much larger version with undercarriage and twin pushers, possibly Whizzza size or larger, but having lost a big chunk of my schedule recovering from my accident, it is "just another project" that will have to wait...

Nigel Hawes.

[MikeS]

I have agree with most that Can Doo caught my attention when I saw the mag on my door step. Nigel mentioned a EDF verson which might worth a wait but still plan to buld this one asap.

Mike

[Colin Leighfield]

Nigel, thank you.

The claim for the canard lay-out as I understand it as that both the wing and foreplane are contributing lift, whereas in a conventional lay-out the tailplane is associated with a down-force. This might not be true I suppose in some of the competition free-flight designs which have a lifting tailplane section and the cg right back on the trailing edge, but in conventional designs with cg between 20/35% back of the leading edge I'm sure it's correct.

Also I think with the canard the main wing stalls first, so you don't get the nose-dropping. I like your idea for a bigger one, it would certainly work and probably be fast as well.

[Nigel Hawes]

That's interesting, I was always under the impression that the foreplane stalls first, so the aircraft simply dips its nose rather than suffering a tipstall!

However as previously iterated I don't have much clue when it comes to the technicalities of design and aerodynamics, I simply clag simple to build models together from the minimum amount of materials possible and they seem to fly ok!

It's easy to forget that the first powered flight was made by a canard, odd that it didn't catch on! When we say "conventional layout" we refer to wings at the front and tail at the back, although I'm sure the Wright Brothers wouldn't have agreed when they built their famous Wright Flyer!

Edited By Nigel Hawes on 30/11/2013 12:19:23

[Colin Leighfield]

You're more right than me Nigel, I'm stretching my memory too far! I remembered that they don't seem to stall, but not for the half-baked reason I just suggested. It's because the foreplane always stalls before the main wing can ever do so, so the nose nods down, reduces the angle of attack on the foreplane, which immediately un-stalls it and everything carries on as if nothing had happened.

Obviously you're also right in that if the main wing can't ever stall, it can't tip-stall either, so it solves that one as well!

There remains the question as to whether they're actually more efficient overall than a conventional lay-out and I think the general conclusion is that they aren't, but they've got some nice characteristics and are certainly interesting regardless.

I think I got up too early this morning.

[Stephen Jones]

Hi ,

The only reason i can think of as to why we do not see too many canards in mass use is due to landing and take off speeds .

The reason why we see planes the way we do is because we need to slow the plane down on approach and usually take off speeds are slower than cruising speed .

I could be completely wrong of course but i think canards have a narrow speed in which they are happy to fly in , however they can be set up to fly slow or fast but not both .

So causing problems when landing or taking off on a conventional runway .

i`m sure someone will correct me soon .

[Colin Leighfield]

This is getting interesting, looks like we'll start to get some answers soon Stephen. After my faux pas on which end stalls first this morning I had a look at some of the opinions on canards. The suggestion is that the self-correcting effect of the foreplane, which in effects prevents the main wing from ever approaching the stall, also stops it from reaching an angle of attack which maximises lift and therefore limits the overall efficiency of the airframe. This might fit in with your thoughts of a narrower speed range and higher take-off/landing speeds?

The Curtiss XP55 Ascender (clever name) WW2 fighter was an attempt to produce a canard rear engined single seat single engined combat plane. It was reasonably quick but generally not brilliant and considered to offer no worthwhile advantages over a conventional design. I think it reflected your suggestions regarding landing and take-off speeds. The Japanese had a go as well (the Kyushu Shinden), but I don't think they managed to fly it before the war's end. It would make a great looking model though, as would the Ascender for that matter!

I don't think any of that changes the prospects of the CanDoo being a great flyer though and it's a perfect opportunity to compare it directly with the Fizza!

[2W]

The Curtiss XP55 Ascender (clever name) WW2 fighter was an attempt to produce a canard rear engined single seat single engined combat plane. It was reasonably quick but generally not brilliant and considered to offer no worthwhile advantages over a conventional design. I think it reflected your suggestions regarding landing and take-off speeds. The Japanese had a go as well (the Kyushu Shinden), but I don't think they managed to fly it before the war's end. It would make a great looking model though, as would the Ascender for that matter!

 

The Kyushu Shinden J7W1 was an interesting plane, and did fly for a total of about 45 mins before the end of WW2. 150 were ordered off the drawing board before it had flown, because the Japanese needed a fast high level interceptor to take on the B-29s. Having a rear engine, the nose could accommodate 4x 30mm cannons each firing 450 rounds per minute. 2 prototypes were built but only one flew, and it was hoped that the J7W2 would be a jet engine version, but the design did not proceed beyond the drawing board. The W1 prototype suffered a number of problems, particularly with engine cooling, and test flying was severely limited by fuel shortages. The remaining airframe was shipped to the USA after the war, and as far as I know it is in storages in pieces in a storage hanger of the Smithsonian Museum in the USA. It used to be possible to see a series of good photos of it on the Smithsonian website, but I can’t find them anymore. There also used to be some good pictures and information on a geocities (?) website, but this is now defunct as far as I can see.

There is some interest in the design in the USA, and a number of different model designs have been built and flown successfully. However, (and I am on uncertain ground here) if the AoA of the canard (front) wing is too great, it can make take off difficult if take off speed is too low, causing it to stall and drop the nose, and as has sometimes happened, it has resulted in a crash before the canard wing can recover sufficient lift. More information on the models can be found here:

http://www.rcgroups.com/forums/showthread.php?t=642695

One day i will build a Shinden to my own design…….

Edited By 2W on 30/11/2013 22:41:21

[DAVE MATTHEWS 2]

Hi everyone, As usual,bonza little plane. built a fizza years ago and had hours of fun with it. My build is nearly complete now but I'll try and post some piccies next week. Power is 300 watts, 3s 2200. Four servos, so elevons front and back (y leads),didn't figure out how to get my futaba T8 to do what I wanted !! BUT, I have made the canopy removeable (magnets) so the battery can be changed without tools. Just got the fins to do so should be maidening this coming week sometime. Good luck to all on the build , Dave

[Colin Leighfield]

Hi 2W and Dave. I know rhe Shinden has been modelled a number of times, I seem to remember even a rubber powered version, perhaps in the old APS Plans Service? Definitely worth having a go, as would the Ascender. (I still think that's funny)!

Good luck with your CanDoo Dave. I built my Fizza when the free plan came along (2005)? and although I haven't flown it for a while I've still got it, so must get it out again.

[Stephen Jones]

i am hoping to get mine finished soon , i made a start on the sanding today but after taking the family to the pictures and shopping by the time i got back there wasn`t much day light left , so i shall have to finish sanding tomorrow now .

I have not got any servos for it yet , so i shall also have to get them ordered soon .

[Piers Bowlan]

Burt Rutan and his Scaled Composites company has produced 38 radical canard type designs, some more successful than others. One problems with the Canard configuration is the down-wash from the forplane interfering with the operation of the mainplane. On the Rutan Solitair motor glider the centre section of the wing has less incidence than the outer portion (which suggests wash-in!). The other problem is that for the aeroplane to be stable in pitch the mainplane does not operate at the optimum angle of attack in cruising flight. Or so I have read at least.

[Colin Leighfield]

Ignore the flying boat! This is out of the Radio Control Manual 3, (1969/70). It looks so much like the proposed jet version of the Shinden, it may be more than a co-incidence!

[Erfolg]

There has been quite a lot of Canards constructed or planned over the years, the FW 42 a planned and mocked up aircraft, the FW 44 Ente (Duck).

Then there were the Miles Aircraft Canards, which were handful by written accounts.

Contrary to common held believes, the canard I built, would stall. I do not know if it is scale effects or other issues. I tried ensuring that the foreplane operated at a higher angle of attack than the rear plane by having a disproportionate wing loading on the foreplane. Blunting the LE of the foreplane to provide a more rounded LE. Strakes to control airflow on the foreplane.

I am not sure that the Cando is a pure Canard having reflex on the mainplane, as a flying wing would use.

[Colin Leighfield]

If I remember rightly Erfolg, the Miles designs (Libellulas)? were classed as tandem wings rather than canards. The single engined M35 certainly flew and once again, I'm sure there used to be a free-flight model of it in the old Aeromodeller Plans Service. The twin also flew, although the jet bomber was only ever a project.

I take your point about the reflex on the CanDoo, although all that probably means is that it needs one or two degrees positive incidence adding on the foreplane. I don't think it means that it isn't a canard.

[Erfolg]

Colin

The difference between a tandem and canard plane is a thin line if it exists at all. Here is a link which may be of interest.

[Stephen Jones]

Hi Erfolg ,

Have you seen my new canard Bipe .

[Stephen Jones]

Hi ,

I finally got some sanding done today .

So thats the wings done now i need to start on the fuzz ,

I think i will start a separate build blog for this one .

[Erfolg]

Ah! Steven, I think you have gone for an all flying top plane?

It will be interesting to know how the model performs. I tried both all moving and the use of elevators on the foreplane.

I guess one of the issues you will not have to put up with is the need/wish to obtain a good glide performance. Yet for me it was the sudden stall, in addition to the difficulty to tow that killed the project. After all what use is a glider which will not max out the towline/bungee potential, and also possess a good glide and ability to keep near the stall when circling in lift.

It is the reflex of the Cando which leaves me with a question mark, with that configuration, is it a conventionally rigged tail first, or a flying wing with a forward pitch control? It probably does not matter though, being a point of academic interest.

[Andrew Russell 2]

I just got my wood to start building my can-doo cant wait to get mine airbourne

On the subject of canard designs here's one that i own and fly it has excellent flying charecteristics at both low and high speed. built in 1980 as a microlight it was years ahead of its time.

[Colin Leighfield]

Erfolg, thank you, can't argue with that and thanks for the link. In Eric Brown's first volume of "Wings of the Weird and wonderful", he describes flying the Miles M39B. He describes the stall characteristics flaps up and down and it comes out pretty innocuous. Particularly he describes the characteristic in the stall of the nose nodding down and the plane coming out of the stall. Apart from that, he says that he enjoyed flying it but couldn't see it as a test aircraft for the Navy.

I've had a look at my CanDoo plan and note that Nigel has drawn in 2 degrees positive incidence on the foreplane and 2 degrees upthrust on the motor. These obviously relate to the original trim issues he refers to in the build article. I'm going to alter the foreplane incidence on the plan to 3 Degrees and see what happens. ( Next after the Pushy Cat, New Year). I just want to see if this takes out the need for aileron reflex and increases lift overall, without making the thrust line wrong.

I like the biplane Stephen.

Andrew, I remember seeing your canard when it came out as a micro-light, wish it was mine!

Edited By Colin Leighfield on 02/12/2013 10:31:53