My Hobbyking Lancaster

[Gordon Nicol]

Posted by Martin McIntosh on 24/11/2015 10:51:29:

Gordon, somewhere on here I posted that I removed the tail wheel and servo after cutting out a chunk under the tail, fitted a micro servo in there then linked it to the rudders under the tail with carbon rods, finally converting the wheel to castor and gluing the foam back in place.

C.A.R. is very desirable but do not use very much rudder coupling.

I was looking at 4.5 gram servos to bury in the rudders but they are a bit expensive, i have a tower pro 5 gram spare that i may do what you suggest, and some 1mm cf rod for the linkage . may also fit a 3mm cf tube across the tailplane for a bit of strength early days yet

[Erfolg]

My Durafly 110 has twin rudders and servos. In that case pockets and slots are moulded into the model. I would be surprised if the Lancaster were not the same.

I cannot say I am enthusiastic user of rudders in general flying in the air. I guess like many I have played about with the rudder as a the prime turning method, when ailerons are present. Much to my surprise a pronounced skidding was observed, when little/non dihedral is present. In the case of the HZ Reliant, being a high wing,  I expected a turning characteristic  similar as with my gliders, which range from small (2m) to big (144" ). This was not the case, in the case of the reliant, it skidded, if you persisted, a wing would stall. I have also tried aileron and rudder (+ elevator) but could not convince myself it was better than aileron. I am sure that purists would ague you should always use rudder in conjunction with other controls, yet from the ground, not any obvious benefit to me. Probably the best use of rudder is a slightly cross wind landing, with just a quick rudder input. In my case it seems any significant, prolonged rudder input only, has results that are not desirable. Although all models may behave differently.

Edited By Erfolg on 24/11/2015 12:09:00

Edited By Erfolg on 24/11/2015 12:09:16

Edited By Erfolg on 24/11/2015 12:26:50

[Martin McIntosh]

Rudders on a Lanc are most essential and should be coordinated with aileron. Ailerons alone on an aeroplane with a lot of dihedral just cause adverse yaw.

The servo I used was an Esky micro digi. Carbon rods are so short that tubing is not required, otherwise you may as well just use the tube as a pushrod.

[Erfolg]

Rather than go for the rudder essential approach, why not differential aileron?

Has the Lancaster got a lot of dihedral?

I have been trying to think of any of my models with a lot of dihedral with ailerons, at first thoughts, I do not seem to have one. I do have a VS Tom Boy which had loads of dihedral, where the dihedral was a nightmare causing vicious Dutch Rolling, condemned as unflyable when the Tx was placed in the hands of the clubs most competent flyer. I have avoided a lot of dihedral ever since.

[Martin McIntosh]

Yes the Lanc has quite a bit. Lots of aileron differential is taken for granted.

[Cliff Bastow]

I have quite a lot of aileron differential dialed in so that there is hardly any down aileron and this seems to work ok.

Gary, my cg is pretty much on the 55mm from the leading edge as suggested in the manual.

[Gary Manuel]

I think I'm going to go the other route for Yaw control - just for the hell of it, and for the technical challenge. Apologies in advance if this is a bit too technical for this particular thread. I can move it to a more appropriate thread if so. If not, I'd appreciate feedback / thoughts on what I'm thinking of doing.

I'm thinking of using separate channels for the 4 ESC's, with rudder stick giving perhaps +/- 20% differential on the two outer motors and 10% on the two inner motors. i.e full left rudder would result in 80% of set power to the outer left motor, 90% to the inner left, 110% to the inner right and 120% to the outer right. This should make it Yaw to the left (I think!).

I can see three potential issues.

1 - It doesn't work as I expect it to!

I guess I'll find out when I try to fly it - It will only take effect when I touch the rudder stick anyway.

2 - All 4 motors need to be turned off during receiver failsafe.

I have a Spektrum AR8000 which has what they call "Smart Safe technology". If it works the way I think it does, the throttle channel is identified by the receiver as being the one that's low at the time of binding - hence the "Smart" name. All other channels should be in the mid position. When the signal is lost and the receiver goes into failsafe, the throttle channel is driven to the low position used at the time of binding, and all other channel hold their current position. What I'm not sure about is how it deals with having four channels low at the time of binding. Bench testing with half a dozen servos should confirm this.

3. ESC calibration sets the output power to maximum, so 120% is not possible.

I would need to set up a switch which gives all 4 channels an end point of 120% so that this becomes the calibrated full throttle. With this switched off, full throttle would be somewhat lower than this (i.e. 100%), which would allow the +/- 20% differential. There is a risk here that all 4 motors at the reduced output gives insufficient power to take off / climb.

I would expect to have to play around with the +/- 20% figure, aiming for a constant TOTAL POWER output regardless of the rudder position. It might finish up at say +10% -30% due to a non linear throttle curve.

 

 

Edited By Gary Manuel on 24/11/2015 18:34:55

[Martin McIntosh]

Best of luck with that Gary. I once tried similar on an o/d delta, the object being to emulate a Vecjet and do twizzles. The ESCs just would not allow it since full power could not be attained for launch. Also tried on an electroslot glider to make it conform with the then local club maximum wattage allowance. Again it did not work because the ESCs only recognised 0% to 100%.

You may yet prove me wrong.

Much simpler to fit a rudder servo.

[Gary Manuel]

Martin,

I don't do simple.

I'm only really thinking of doing this because I'm not really into warbirds, but who doesn't love to see a Lancaster or Spitfire eh? I'm hoping that the technical challenge will keep me interested enough.

I understand exactly what you are saying about ESC only recognising 100% throttle - that's what I was thinking about in point 3, even if I didn't explain myself properly. Effectively, I expect to calibrate at 100%. Throttle for flight then effectively becomes something like 83.3% +/-20% (i.e 100% max, 66.7% min). I'm sure it will take a lot of experimentation and will only work if there is enough power for flight at 83.3% power.

 

P.S. - I've started another thread HERE, in case this is too technical for this thread.

Edited By Gary Manuel on 24/11/2015 19:03:51

[Gary Binnie]

Tempting!

I am just loading this into my car for the club members to look at tomorrow evening.

102" span (1/12 scale) I helped my father to build it in 1977, appeared at Old Warden once if I remember correctly.

Ignore the transmitter, it's just for scale, yep, it was designed for free flight!!!!!

[Gary Manuel]

Mines just arrived.

Ordered on 23rd, received on 26th from the Netherlands.

Not bad going for free delivery

[J D 8]

Posted by Gary Binnie on 25/11/2015 13:32:25:

Tempting!

I am just loading this into my car for the club members to look at tomorrow evening.

102" span (1/12 scale) I helped my father to build it in 1977, appeared at Old Warden once if I remember correctly.

Ignore the transmitter, it's just for scale, yep, it was designed for free flight!!!!!

With today's rc gear and electric set up's think it would be possible to convert it to radio control ?

[scott finnie]

A better wing section to make her float and it would be a perfect throw in the boot Lancaster. It looks like it needs to be kept going excessively fast to avoid disaster. Shame as it looks great

[Erfolg]

Although my model is the Durafly 110 I do think that there are a number of issues that work against what are essentially small models.

In the case of the 110 and I suspect the Lancaster, which is a modest wing area.

The smallish wing area would be fine other than in the case of my 110, I used 14 AWG leads from the escs to the Lipo. There is a lot of heavy wire. In retrospect I would have done better to use lighter gauge something like 11 AWG and live with higher transmission losses. The second issue is the UC although the web site weight is low, in your hand, they feel anything but light.

It is these issues which I think have an adverse impact on the handling, requiring quite a lot of speed to keep flying consistently.

I have so little confidence in the performance of the model, to the extent I have delayed the flight of this second model, until the undergrowth around our field has died back. That is so i stand a chance of finding the bits if it goes in on the test flight (or any subsequent flights) until I am able to build confidence in the model.

Edited By Erfolg on 26/11/2015 10:54:40

[Keith Simmons]

Chris, the 1/12th Lancaster looks lovely. Can I ask what's the weight?

[Gary Manuel]

Having got the differential throttles working to simulate rudder control, I thought the HK Lancaster would be a simple build, but then I had a closer look.

I had half decided to remove the undercarriage and go for hand launching and belly landing, so I unscrewed the retracts to see what I was up against. The retracts are screwed into a number of "laminated" 1/8" lite ply plates, glued into the undercarriage bays. Once the screws are removed, it becomes clear the the plates are not actually laminated, but are just held in by the glue bond to the foam body. This is an obvious weak point, but does make it easy to remove them by running a blade between the foam and plates.

Once I got the retracts and ply plates out, I had a clear view of the ESC's. The two inner ESCs are burried deep in the nacelles, almost completely surrounded by foam to keep them out of the way of the retracts. They have very little, if any air flow over them. The position of the outer ESC's is much better, but the air exit holes are about the diameter of a pencil (i.e. useless).

The flaw in my plan to belly land the Lancaster is that it has three blade props, which will ALWAYS be catching on the ground, regardless of which position they stop in. I would anticipate breaking at least one prop per landing. I therefore decided to reinstate the undercarriage (after testing that they both worked OK) and retain the steerable tailwheel. Unfortunately, in order to retain differential throttles, this means that I now need ALL 9 channels on my radio - 4 motors, retracts, tail wheel, 2 ailerons and elevator. 10 Channel Lemon RX10 now on order. This is only because I am experimenting with differential rudder.

Here's what I've done to improve the build issues - I would recomend these easy fixes to anyone building this model.

1. Laminated the 1/8" lite ply blocks to create a solid block, which should strengthen this particular weak spot.

2. Repositioned the INNER ESC's so that they are inline with the air intakes (where you would have expected them to be) rather than burried in foam, in order to keep them cool. This means re-routing the wiring underneath / in front of the retracts before gluing the strengthened blocks back in. Exit hole size is not a problem due to the undercarriage holes.

3. Greatly increased the size of the air outlet hole in the OUTER nacelles. The angle of the cut is made to face rearwards to creat a negative pressure area to "suck" air through the nacelle. The freshly cut white foam will need spraying black to match the surrounding paint work.

4. Check that all servos are firmly glued into the foam cutouts.

Just waiting for glue to dry overnight, then I'll be back to where it should have been as it came out of the box.

[Cliff Bastow]

Just a quick update after a few flights now. All in all no problems have been discovered until my last attempted flight.

On opening the throttle for take off the model swung sharply left. I quickly shut the throttle and no damage done.

Upon walking to the model and holding the fuselage whilst running up the engines I noticed the port outer was not working!

On closer inspection back in the pits I could see the prop was at a strange angle and the spinner was binding on the front of the nacelle. After removing the nacelle front it became clear that the motor mount which is part of the nacelle front had shattered into several pieces allowing the motor to move about. I suspect this had happened on the last flight as I always belly land the model as I don't think the retracts will cope with a rough field landing.

I have repaired this with a plywood former epoxied into the nacelle as a new motor mount but now I am a bit concerned that this could lead to prop breakages now as Gary suggests in his post above, although this has not happened on any motor to date after several landings. One to watch I think.

Perhaps I will have to try and land wheels down and trust the U/c as its seems to cope well enough on take off.

[steve Scott 2]

Hi to everyone who has posted about the HK Lancaster and I've found all of your posts very interesting especially about the tip stall and high angle of attack in turns etc. I purchased one of these Lancs a few weeks ago, brand new from Hobbyking and on opening the box I was plesently surprised at the appearance of the model, granted not a class 1 scale model but nice all the same. I did however have concerns about the weight of the wings and having the afforementioned problems of tip stall and angle of attack in my mind I looked at the wings with the intention of trying to create some washout when on looking at the root and tip rib sections I made the shocking discovery that the rib/wing section is infact upside down!!. It appears the original wing plug sections have been made inverted prior to molding!. An unbelievable mistake by the producers of the Lancaster and a mistake that would certainly go some way to explain the tip stall, high angle of attack and lastly, the high flying speed. I'd be very interested to hear from any previous posters to see if your lancasters wings have the section upside down too, ie the more curved surface is wrongly at the bottom!!

[ben goodfellow 1]

flew my pals down at the beach a month or two back. have to say wasnt half as bad as i expected ... dont like slow flight though...fly low

[Gary Manuel]

Got the chance to maiden mine on Saturday. It's taken all this time to get the grass cut and field dried out.

Take off was dead straight and gently lifted into the air with no problems at all. I didthe first couple of circuits at pretty high speed baring in mind the reports of tip stalling etc. Wind was pretty gusty up to about 15mph so it was a bit twitchy but looked well in the air. Flew OK and needed NO trimming!

Flicked Flight Mode switch and the differential throttles worked well to simulate rudder control, but were a bit on the feeble side. I slowed her down for a couple of low passes for the camera. Thanks to Mark for these excellent shots.

First landing was made with plenty of air speed straight into the wind - text book.

For the second flight, I doubled the the differential throttle mixes to 40% inner and 20% outer. Felt much more like a propper rudder control, but resulted in a fair bit of nosing down, requiring up elevator to compensate - it would have been nice to add a bit of rudder to elevator mix on the transmitter. Unfortunately, I've used all 6 mixes (see differential throttles link in my post above).

I then tried reducing the airspeed to see what the fuss was all about, and found out almost instantly! Tip stalls came in thick and fast - and severe. I went back to flying faster and she started behaving again. Unfortunately, I dropped the speed off a bit too much on landing and made quite a heavy contact with the ground. A bit of damage, but easily repaired.

Flew her again on Sunday with similar results. My conclusion is that this isn't as hard to tame as has been reported. She does need full concentration - all of the time and is definitely not a relaxing model to fly. Not really my type of model, but I've enjoyed the technical challenge of getting the differential throttles working. Worth every penny of the £60 I paid and I'm sure it will be popular at our club open days.

[Gary Manuel]

Posted by steve Scott 2 on 09/05/2016 21:10:52:

Hi to everyone who has posted about the HK Lancaster and I've found all of your posts very interesting especially about the tip stall and high angle of attack in turns etc. I purchased one of these Lancs a few weeks ago, brand new from Hobbyking and on opening the box I was plesently surprised at the appearance of the model, granted not a class 1 scale model but nice all the same. I did however have concerns about the weight of the wings and having the afforementioned problems of tip stall and angle of attack in my mind I looked at the wings with the intention of trying to create some washout when on looking at the root and tip rib sections I made the shocking discovery that the rib/wing section is infact upside down!!. It appears the original wing plug sections have been made inverted prior to molding!. An unbelievable mistake by the producers of the Lancaster and a mistake that would certainly go some way to explain the tip stall, high angle of attack and lastly, the high flying speed. I'd be very interested to hear from any previous posters to see if your lancasters wings have the section upside down too, ie the more curved surface is wrongly at the bottom!!

I'll have a look at mine tomorrow and report back.

[john stones 1 - Moderator]

I watched Gary fly his, very impressed, looks a bigger model when it's airborne it's a scale model with a bit of weight to it, so I reckon it behaved very reasonably myself, and as for having to work at it...that's a plus point I think

John

[Nigel Luther]

Sorrry to bring an old thread to life again ... but I have been flying the HK Lancaster for about 1.5 years now and to be honest feel she has bad press from many.

If people want a scale flying slow bomber - then they need to think bigger - this is a compact model that was never designed to be a slow scale flyer.

But even so - the way to fly this is not like a Yamamoto or intermediate trainer - which unfortunately many seem to think. You can slow this on straight and level but when coming into and making the turn - give it some boost to help it round.

Yes I've had my stalls ... but very few in fact. Because I power round the turns. Landing ... you need like the full size to line her up and keep power on - set that glide angle to bring her in ... only chop power once she is ON the ground. I tend to fly her to the ground with a voice in the head saying too fast too fast too fast ... I resist the temptation to cut throttle more ... grease her in. I even keep power on and slowly reduce to create the roll-out ...

 

I fitted 5gr servo to each rudder s a modification but to be honest - wasted effort. I have a + / + 15% Differential throttle setup side to side operates with rudder.

+ / + means I have no minus differential. That way I do not risk one side reducing power when rudder applied.

I have installed an Orange Stabiliser that has very low normal gain just to assist in wind gusts etc. I could easily remove it in fact and probably not notice any difference. But its nice to know its there assisting.

She's sitting on my bench all ready to go again ... about 1.5 years old ...

 

Here's the maiden at an ex Soviet Mig Fighter base ....

 

https://www.youtube.com/watch?v=b1AhgvAU5O4

 

 

and one of the later flights not so long ago ...

 

 

https://www.youtube.com/watch?v=O2VgpctUajs&t=330s

 

 

OK ... modifications / tips ...

 

1. The prop hubs are too thick for the length of shaft and the prop nut doesn't get enough threads on. Better to swap props for 6x4 MAS 3 blade props.

2. Spinners have quite a gap to the cowl - the MAS props help again.

3. Retracts are screwed to multi laminated ply form .... with short self tapping screws. Do not beef up with any more glue etc. - just swap out the screws for longer ones. Also while retracts are out - lightly sand the cut-out so its not so tight on the retract plastic, which can make them bind.

4. The Mk2 later version without gear doors etc. - the battery (2250 3S 30C is perfect) should sit in front of but pushed back against the wing foam bridge.

5. CoG should be 55mm from leading edge at root.

6. Separate the motor controls and program differential throttle side to side ... I suggest programming only +ve action with no -ve ... to avoid one side motors reducing too slow.

 

If you have misfortune to break the plastic Motor mount inside the cowl ... best repair is a disc of thin lite ply, I use a Hole Cutter in electric drill to produce the disc...

Break away the snags of plastic but leave the outer ring ... epoxy the ply disc on the INSIDE of the ring to create a ply firewall. Screw motor to this.

This may out spinner hard up against cowl now - a prop shaft adaptor ring in the spinner then moves it out enough to clear.

 

If you run out of 3 blade props - 2 blade 6x4 fly her literally same .. I tried it and no problem.

 

The HK Lancaster may not be everyones cup of tea - but I love mine and I would buy another if mine ever got that bad ...

 

For more scale flight - I am slowly getting together Chris Golds 93" Lancaster ... using pine and depron ...

 

Nigel

 

Edited By Nigel Luther on 05/03/2017 13:33:35

Edited By Nigel Luther on 05/03/2017 13:34:17

Edited By Nigel Luther on 05/03/2017 13:35:23

[Paul Marsh]

Mine flies very well. I prefer a model which isn't too easy to fly, I get bored otherwise.

When I've flown it, I deliberately flown it into the stall - at low level and recovered easily, because anyone with decent flying skills will fly this model - people who've crashed is because they've expected a floater, when it isn't.

A couple years ago, there were three of us flying the same models, in formation, and when slowed down to almost standstill, all 3 models stalled at once, did a tumble and all three carried on flying - no problems.

[Nigel Luther]

Tks ... Glad I am not only one !

Cheers

Nigel