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>> Home > Forum > Boat Specific Chit Chat! > Graupner Elke HF 408
Graupner Elke HF 408
(3446 views)
Author Message
AllenA
(Fleet Admiral!)





Forum Posts: 96
15th Jan 2018 11:26  
>> Permalink
mdlbt.com/37405

Hope you are not becoming too bored with my boot sale stories but I seem to have hit a rich vein at the moment and can't resist. Here's the Graupner Elke HF 408 picked up on Sunday for £14. Pretty good nick with lots of bits and does not appear to have been sailed or fitted with RC. Again, any help or advice really welcome. Retro fitting a propshaft could be a problem.


Attached Files - Click To View Large

AllenA
(Fleet Admiral!)





Forum Posts: 96
15th Jan 2018 14:57  
>> Permalink
mdlbt.com/37409

Forgot to say... I found these..see photos inside the Elke. On the back of the card it says Xmas 1943. God Bless Trumpeter and all who sailed in her and flew from her. God bless Captain Harry Oram.


Attached Files - Click To View Large

Tica
(Lieutenant)





Forum Posts: 11
16th Jan 2018 19:41  
>> Permalink
mdlbt.com/37464

Hello Allen

I believe that I do have the full instructions and plan with my half build kit of Elke, I can dig it out and check it out, and if they are there, I can take some pics of it if you need it ?

BR
Carsten


www.skalamodelskibe.dk
AllenA
(Fleet Admiral!)





Forum Posts: 96
16th Jan 2018 20:48  
>> Permalink
mdlbt.com/37466

Thanks Carsten,
That would be brilliant if you could.
Best Regards
Allen

Tica
(Lieutenant)





Forum Posts: 11
17th Jan 2018 18:49  
>> Permalink
mdlbt.com/37500

PM with link send 😎


www.skalamodelskibe.dk
SelwynWilliams
(Fleet Admiral!)





Forum Posts: 40
25th Jan 2018 20:00  
>> Permalink
mdlbt.com/37897

You got a bargain with that boat, where are you? Was it a boat sale?

AllenA
(Fleet Admiral!)





Forum Posts: 96
28th Jan 2018 10:47  
>> Permalink
mdlbt.com/37989

Elke stripped down, cleaned and base colours flatted. Hopefully, on the water in about a month. I read somewhere that she, originally, had a 300 motor and with a narrow propshaft gap I am down to a 2mm propshaft, 4mm OD. Looking in my motor box I have a 300 motor with 2:1 gearing set up. Actually fits perfectly as the propshaft has to be low to the keel. I plan to use a 30mm 3 blade propeller, because I have one in my box, and hope, that even though it is slightly big for the motor which is 25mm diameter, I will escape any undesirable consequences. Noticeably, the stanchions and safety ropes only run along one side of the deck. I assume that this is to facilitate nets being brought in on the open side?


Attached Files - Click To View Large

AllenA
(Fleet Admiral!)





Forum Posts: 96
20th Feb 2018 11:33  
>> Permalink
mdlbt.com/38919

Elke HF 408 now refitted. Running on a Mabuchi motor geared 2:1, 2mm shaft and 30mm 3 blade propeller. Still fiddling with the ballast but almost ready to sail. Yet to find a suitable fishing net to suit 1:36 scale. Control is via a 40mhz Hitec Ranger 3, Acoms receiver and Chinese 320A fan cooled ESC. As they would say in Cardiff she looks tidy. Many thanks to Tica/BRCarsten for photos of the plans.


Attached Files - Click To View Large

RNinMunich
(Fleet Admiral!)





Forum Posts: 2495
20th Feb 2018 12:27  
>> Permalink
mdlbt.com/38927

Wow! So much done in 3 weeks! Brilliant 👍 Look forward to the Maiden report.
Love the woodwork, nice job. Inspiration for my Danish cutter refit😉
Would have thought that a 320A ESC is a bit overkill for a 'plodder'!?
But, if was 'in the box' ...

I'll be putting a 10A mTronik in my cutter, with a modified Taycol Target, ca 6A max (I hope!) Nothing doing here at the moment, everything frozen over and it's snowing again 😡 Cheers Doug 😎


Young at heart - slightly older in other places 😉 Cheers Doug
AllenA
(Fleet Admiral!)





Forum Posts: 96
20th Feb 2018 13:04  
>> Permalink
mdlbt.com/38930

Thanks Doug. I am not sure I would rely on my Chinese friends' measurement of amps but I have used a few of the ESCs and they haven't blown up yet. How would I go about testing the amperage? I have my little unused Watt Meter. Do I, simply, connect it between the battery and the ESC and take the reading while running the motor? Sorry to hear about the snow, we are just moving into Spring. Primroses and Daffodils are out and days are lengthening. At last.


Attached Files - Click To View Large

RNinMunich
(Fleet Admiral!)





Forum Posts: 2495
20th Feb 2018 13:39  
>> Permalink
mdlbt.com/38932

Hi Allen, I heartily agree Chinese specs should be taken with a generous pinch of salt 😉 But even a quoted 'peak 320A' ESC should be able to handle 100-150A which is probably 10 to 12 times what you will need for the little Mabuchi.
Your Wattmeter is almost identical to mine👍 Connect battery to the 'Source' wires and 'Load' to the ESC and away you go. Do the test with the prop / motor under load, i.e. in the domestic test tank!
Don't forget the Souwester!! 😉
I'll be surprised if the full ahead test is more than 10A.
Have fun, Doug 😎
Primroses and daffs are only out in the Garden centres and supermarkets here, be another 4 weeks or so before much happens outside. 🤔Although my Winter Jasmine is still bravely blooming bright yellow 😊


Young at heart - slightly older in other places 😉 Cheers Doug
AllenA
(Fleet Admiral!)





Forum Posts: 96
21st Feb 2018 11:19  
>> Permalink
mdlbt.com/38952

Hi Doug, I put the Watt Meter to use and with about 16ozs of ballast, might need a bit more, had 6.77 amps at full forward with just over 40 watts . At complete stall with prop spinning she jumps to 40 amps which I guess is to be expected. She is, obviously, too fast for scale so I will need to control via the Tx. Might look for a smaller propeller.... what do you think? Thanks for your help.

RNinMunich
(Fleet Admiral!)





Forum Posts: 2495
21st Feb 2018 12:21  
>> Permalink
mdlbt.com/38954

Hi Allen, so you were running off a 6V batt, results are about what I expected👍 Well done that man😉
You could go down to a 25mm prop. And don't forget to put a 10A fuse in the motor + supply wire to avoid frying the motor and or wiring if it stalls at sea!! 😉Have fun, Doug 😎
PS: snow's stopped, sun's out 😊 Still bl...y cold though😡


Young at heart - slightly older in other places 😉 Cheers Doug
RNinMunich
(Fleet Admiral!)





Forum Posts: 2495
21st Feb 2018 13:36  
>> Permalink
mdlbt.com/38956

On reflection Allen, maybe you should try her on the lake before you change props? Looking at your photos again - she might look a tad daft if the prop is any smaller 😉 if you still think she's too quick maybe try a 30mm with less pitch? Look forward to the maiden report 😎


Young at heart - slightly older in other places 😉 Cheers Doug
AllenA
(Fleet Admiral!)





Forum Posts: 96
21st Feb 2018 16:05  
>> Permalink
mdlbt.com/38959

Agreed Doug. The Rookie forgot the fuse again.

RNinMunich
(Fleet Admiral!)





Forum Posts: 2495
21st Feb 2018 16:22  
>> Permalink
mdlbt.com/38960

A 'rookie' Fleet Admiral !!?? 😲


Young at heart - slightly older in other places 😉 Cheers Doug
AllenA
(Fleet Admiral!)





Forum Posts: 96
21st Feb 2018 16:36  
>> Permalink
mdlbt.com/38963

'So 'ark an' 'eed, you rookies, which is always grumblin' sore' (Rudyard Kipling)....... until it comes naturally I remain a Rookie. I'll give you a shout when I get to 90 and, hopefully, still afloat then I will deserve it.

Dave M
(Fleet Admiral!)





Forum Posts: 1527
21st Feb 2018 16:58  
>> Permalink
mdlbt.com/38964

Hi Allen
Model has come along fine and should look good on the water.
Interesting stats especially the stall current. This would rate the motor at 280 Watts with your 7.2v battery
Do you know which type of 300 motor you have installed? Many were 6v max but they have versions that go to 24v.
There should be markings on the case and you can check the specs at https://product.mabuchi-motor.com/search.html?method=4.
I used two 12v versions in my Billings Coast Guard with 35 mm direct drive props on 12v and they were power hungry, drawing about 4amps each. With your reduction unit I would expect the current to be a lot less than the 6.77 amps you recorded.
I agree with Doug's suggestion that you sail it and see. I would suggest a quick circle on the water and then check the motor temp.


Live long and prosper

Dave
AllenA
(Fleet Admiral!)





Forum Posts: 96
21st Feb 2018 20:09  
>> Permalink
mdlbt.com/38971

Hi Dave, Can't find the motor I have on the Mabuchi site. My guess it is quite old. I think it is a TD 224 that I picked up at a boot sale from a model plane enthusiast. So far I have run it on a 7.2v nimh so will change to 6v asap. I gave it full throttle in the bath and no sign of heat or fumes in battery, motor or esc. Thanks for the help. As you say a quick turn around the lake is in order. The fuse advised by Doug is now installed.

Dave M
(Fleet Admiral!)





Forum Posts: 1527
21st Feb 2018 22:26  
>> Permalink
mdlbt.com/38977

Hi Allen
I did wonder if it was an ex flyer type as it had the gearbox.
The markings can help but not possibly in this case. The other major supplier was Johnson but I can't find your TD224.
I suspect this will be a high current fast rev motor probably 12v max. To work with your model I think you will be well advised to follow Doug's suggestion and fit a 6v battery.

If you can see the windings inside the motor case and they are thick and few then it is a fast and high current motor.
The prop looks like a Graupner and is fine pitch and similar models in my club have a nice brass prop of fairly coarse pitch to give a good slow scale speed. The gearbox will allow you to fit a brass prop of similar dimensions to yours.
Initially I agree with Doug though, just pop it in the water and see how it performs.
With your luck you will probably source a suitable prop from the car boot sales!

Finally
As the motor is old it could have shorted windings, in which case it's going to get hot. If you have a good multimeter you can check for low resistance between the case and one of the motor connectors. Use the highest Ohms setting you have and rotate the motor shaft a full revolution, repeat with progressively lower Ohms settings. You should have good insulation between the windings and the case, if you are getting any ohm readings chances are there are shorted windings on the armature and the motor is terminal.


Live long and prosper

Dave
RNinMunich
(Fleet Admiral!)





Forum Posts: 2495
21st Feb 2018 22:57  
>> Permalink
mdlbt.com/38979

Veeery interestink!😉
I always thought that a motor's power rating referred to it's useful power output, not what it scoffs when it is stalled 🤔 Sure 40 x 7.2 = 288W but your full ahead current and watts measurement says the supply voltage was approx 6V.
Interestingly some history research tells me that the Elke was originally intended for and supplied with a direct drive 280 motor. Graupner still lists it as such, albeit as 'Sold out' 🤔
Several German build blogs on the net confirm this, although others have also tried different motors, including Decaperms. Kit reviews (mostly on German sites) also mention that she was 'pretty quick' with the 280 motor.
Can well imagine, I have 2 x 285s in my 107cm U-25 and she goes like a bat out of hell. 😉
Allen; your result of 40W + and 6.77Amps tells me the motor was running on roughly 6V. (40/6.77=5.91) If you really had a 7.2V pack connected it's got a duff cell (collapsing under load or short circuit) 😲 Carefully strip the pack, isolate the duff cell using a digital voltmeter, cut it out and send it to the great recycling nirvana! Then you have a powerful RX battery😉
Glad to hear you fitted the fuse👍 Leave the rest alone for now and sail her and see. I believe you will be more than happy with the performance and since the ESC is over dimensioned it should have no problems. Happy sailing, Doug 😎


Young at heart - slightly older in other places 😉 Cheers Doug
Dave M
(Fleet Admiral!)





Forum Posts: 1527
21st Feb 2018 23:17  
>> Permalink
mdlbt.com/38981

Hi Doug
I was referring to watts produced by the battery in the model and the quoted amps of 40. I made no mention of the motor's power rating.
The battery looks ok to me and would struggle to give 40 amps with a duff cell.
I agree the best course is to suck it and see as is. May sail fine and the motor not overheat.


Live long and prosper

Dave
RNinMunich
(Fleet Admiral!)





Forum Posts: 2495
21st Feb 2018 23:39  
>> Permalink
mdlbt.com/38983

Evenin' Dave,
"Interesting stats especially the stall current. This would rate the motor at 280 Watts with your 7.2v battery" 😲

If the battery pack was 7.2 volts nominal and was 'healthy' then according to Allen's measurements it was down to an average of about 0.98V per cell. Also not so healthy for a NiMH. 5.91/5=1.182 volts per cell. A healthy voltage for NiMH 😊 Indicates a shorted cell if it was a 7.2 pack, and the healthy cells could still deliver 40A for a short while.
If the boat needs ballast anyway I would go for the useful ballast of a 6V SLA. Which is what I intend to use in my Danish cutter with the Taycol Target. Such boats don't need the short term, high current that NiMH and LiPos can deliver. G'night All, Cheers Doug 😎


Attached Files - Click To View Large


Young at heart - slightly older in other places 😉 Cheers Doug
RNinMunich
(Fleet Admiral!)





Forum Posts: 2495
22nd Feb 2018 01:07  
>> Permalink
mdlbt.com/38988

BTW Allen, Dave's comments re 'old motors' go in the right direction but the basic thought and measurement technique are not quite right.
There should never be ANY ohm meter reading between armature coils (i.e. motor supply connections) and case! Do by all means try this, but anything less than infinity, '---' on most digital meters, means a scrap motor😡 This test really requires an insulation test using what is commonly called a Mega meter. This has a crank generator which puts high voltage (ca 1000V+😲) across the unit under test. It measures the insulation resistance in millions of Ohms, hence the name Mega!
For us modellers not a particularly useful or practical test!

The most common form of deterioration in old motors is cracking and flaking of the insulating varnish of the armature windings. This does not normally cause shorts or spurious measurable resistance to the case but causes internal shorts in the windings thus reducing their resistance and therefore increasing the current they draw for a given voltage applied, as Dave indicated.
There are two ways you can check this, if you have a decent Ohm meter, one less, one more accurate.
The less accurate is done externally by measuring across the normal motor connections and thus include the resistance of the brushes and connections. Connect the meter where you normally connect the output from the ESC.
Slowly rotate the motor so you can feel the slight 'click' as the motor moves from one winding to the next (or one magnetic pole to the next if you like😉)
You should see a few Ohms resistance at each pole. Value depending on the quality of the carbon brushes. Better quality brushes (more copper content) = lower resistance. Note and compare each 'pole' reading.
If one 'pole' reading is significantly lower than the others then that winding has an internal short😡 The motor may overheat in that winding, depending on how many wires are affected, and fail eventually.
The more accurate method is to dismantle the motor and measure the winding resistances directly at the commutator, i.e. without the brushes in circuit. But this is only useful for nuts like me 😁 as in my 50 year old Taycol Target renovation. I was lucky no shorts and all windings same resistance + or - a gnat's whatsit!😊
Sooooo, to cut a long story sideways😉I think it's very unlikely your motor has any internal problems. I recently found one of the ancient Mabuchis I originally fitted in my HMS Hotspur destroyer 51 years ago, it still clattered along, bearings shot but electrically still OK 😊
Just take what you've got now down to the lake and give her a Go. If she looks right then she most probably is! As my German colleagues would say "Always a hand's width of water under your keel". Cheers Doug 😎
PS: "But trust me on the sunscreen" 😁


Young at heart - slightly older in other places 😉 Cheers Doug
RNinMunich
(Fleet Admiral!)





Forum Posts: 2495
22nd Feb 2018 02:26  
>> Permalink
mdlbt.com/38991

Re Prop (or screw pitch) ...
If the prop blade was a complete screw it would advance through a solid at the rate of NP, where P is the pitch of the blade (prop) and N the rotation speed (Revs) of the driving shaft.
Therefore for given revs of the motor a coarser pitch will result in more speed. Conversely finer pitch = less speed. Which is why I suggested perhaps a 'scale' prop with finer pitch.
Of course the above refers to motion through a solid. Ya gotta start somewhere😉
I can provide the maths for extrapolation to slip (slip ratio) in a fluid medium ..... if anyone's really interested 😉


Attached Files - Click To View Large


Young at heart - slightly older in other places 😉 Cheers Doug
AllenA
(Fleet Admiral!)





Forum Posts: 96
22nd Feb 2018 09:50  
>> Permalink
mdlbt.com/39000

Hi Dave and Doug. I love it when you two start chatting it's like tipping a cornucopia of knowledge all over the floor of my workshop.
I found my original notes and the motor is a Mabuchi TD224 23.
The shafts are: S.H.G Marine Miniature Propeller Shaft Assembly
Stainless Steel Propeller Shaft assembly with Brass Outer Tube
M2 Diameter Shafts

An excellent range of miniature shaft and tube assemblies with Grade 303 Stainless Shafts and Hard Grade Brass outer Tubes.
The outer tube diameter is 4mm, Shaft Diameter 2mm The Bearings are Oil / Water lubricated Acetyl material and are extremely hard wearing and quiet, The Shafts are Threaded at one end with an M2 Thread. The propellers are:
RADIOACTIVE MA 3045 RC MODEL BOAT 3 BLADE 30MM PROPELLER M2 THREAD 2 OFF.
As my Nimh battery is reading 8.09v so it's unlikely that there is a weak cell, I will recheck all the readings and be a little more precise to ensure I am not leading you on a wild goose chase. The biggest clue is that I have just measured the battery holder plate. The measurements are L130mm, H36mm and W65mm. Looks like the only battery that will fit is the PS-630 6V 3.0Ah 150mA 134(L) x 34(W) x 60(H)mm 0.7kg or similar. This looks right as it will probably take care of the ballast issue and it's no wonder my normal 6v battery wouldn't fit. It will be a couple of weeks before I can put her on the lake but at least the battery is ordered. Thanks again for all the info. One final thing... Can you tell me how to measure propeller pitch?


Attached Files - Click To View Large

Dave M
(Fleet Admiral!)





Forum Posts: 1527
22nd Feb 2018 10:28  
>> Permalink
mdlbt.com/39004

Hi Allen
Mabuchi no longer list details of your motor and as it is from an ex flyer chances are it has been cooked at some time in its life.
I agree it is not easy to check for shorts but a reasonable meter will show any major problems.
Your battery sounds fine.

Pitch is often marked on the props near the boss but an explanation I have seen on the web:
Pitch: theoretical distance the prop travels on each rotation. This is theoretical because water is not a solid medium and the prop slips. 10 to 30% is normal, the lower numbers are found only on hi-performance props, specially prepared.
Constant Pitch: the pitch is the same across the entire propeller's working surface, or blade face.
Progressive Pitch: the pitch is lower at the leading edge and increases progressively along the trailing edge.

Consider a prop that runs in a liquid media with a constant pitch, the tip of the prop rotates faster than the hub. Conversely, if the angle at the tip is lower, the water speed on all prop surfaces will be the same. In this case, the performance is far better. Progressive pitch props offer better planning performance.

So if you were to get some graph paper or paper with 1mm markings and set the prop on a shaft over the paper and measure the start point then rotate thro 360deg and measure the finish point this will give you the theoretical pitch.

Over the years I have amassed a fair number of props and usually try various before I decide on the best for the model.

Try what you have with the 6v battery (looks just right for the model) and see how it sails.
From experience I know that this type of model is difficult to get going and all our club models have coarse pitch brass props. Speed will depend on the motor but with a geared motor you should be able to reduce the revs to give scale speed.

I look forward to hearing how you progress in a couple of weeks.


Live long and prosper

Dave
AllenA
(Fleet Admiral!)





Forum Posts: 96
23rd Feb 2018 15:32  
>> Permalink
mdlbt.com/39069

Problem solved for the moment with insertion of correct battery. Battery arrived this morning, ordered yesterday... great service! Power Sonic PS 630 ST 6v 3.4Ah £7.75. Readings (average) 6.05V, less than 1.7 amps, less than 10 watts. Will update after maiden voyage. Thanks again for all your help. ps site does not appear to support less than symbol.


Attached Files - Click To View Large

RNinMunich
(Fleet Admiral!)





Forum Posts: 2495
23rd Feb 2018 15:52  
>> Permalink
mdlbt.com/39072

Good stuff Allen👍
Look forward to the sea trial report; design speed etc.
>>>>> odd that works but if you type 'less than' symbol it and everything after it vanish on posting! Weird 😲


Young at heart - slightly older in other places 😉 Cheers Doug
Dave M
(Fleet Admiral!)





Forum Posts: 1527
23rd Feb 2018 16:27  
>> Permalink
mdlbt.com/39077

That is much more like I would have expected. The motor is clearly a 6v version and running over voltage accounted for the previous high readings.
Hopefully when you get it in the lake the prop will be suitable and the power will be sorted.


Live long and prosper

Dave