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Author Topic: What Did You Do Airplane Wise Today?  (Read 109826 times)
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p40qmilj
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« Reply #1325 on: February 23, 2019, 08:57:49 AM »

 Grin  dime scale p40
built tail feathers, fuselage box
wings in progress. photo of parts to be posted when components complete

jim Grin
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Prosper
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« Reply #1326 on: February 24, 2019, 05:08:36 AM »

Thanks Urs - I'll do that with new motors in future.

Today I sneaked out onto a corner of my neighbour's field in the fog - I shouldn't be walking on it probably, with the grass still on the frail side, but I couldn't resist trying my new supercap test model with a full tank and throttle wide open! I used a new pair of batteries - the first set is down by nearly half a volt. If I continue this game I think I'll use the full-power phase of the batteries for flying, then put them to domestic use - electric clocks and suchlike.

Anyway I got this video. I think in warm dry air and with a more open turn radius more can be expected - and I've no idea whether I'm near the optimum regarding the prop/motor combo. I'm pleased (and surprised), because this model is no lightweight; the wingloading is right in the same neck of the woods as all-sheet WWII monoplanes I've made in the past. The weight and loading is the same as in reply#1321 above, but I cut down the prop slightly to 110mm (4 1/4-ish inches) and increased pitch slightly. I noticed in short flights yesterday that what should be a pretty stable model was showing odd misbehaviour, and this reminded me of the behaviour evinced by rubber scale models I've flown with too-fine prop pitches. The current pitch is 17deg at 75% radius which I think is a PD just over 0.7.

Apart from tinkering with this model, I think it's time to consider ducted fans. As I drowsed waking up today I also thought of the scale subjects I've rejected as rubber models because (mainly) of tragically short noses, and ones I've made that wouldn't fly. I made a Supermarine Spiteful that was a complete failure due to the required noseweight. I wish I'd kept the carcass, to try it with a supercap setup. . .

Stephen.
P.S. the noise these things make is annoying but it's not nearly so irritating in reality as on the vid. The camera mic really exaggerates the noise level.
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p40qmilj
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« Reply #1327 on: February 24, 2019, 11:15:53 AM »

 Grin dime scale p40 wings now built should have fuselage configured by tonite
jim Grin
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« Reply #1328 on: February 24, 2019, 12:53:16 PM »

You're on the gallop today Jim Smiley. Look forward to the pics.

Here's another supercap flight on my own patch - warmer dryer air maybe but I didn't dare trim a wider turn - just as well as it would have hit something. It landed before the capacitor was completely discharged and this time had 18.5° blade pitch as best I could measure. I probably need to go finer again. I may try reducing the blade size also, but it seems to me that against motor efficiency must be set propeller efficiency - it seems to me there's no good in having a motor working at its best if to do so means it has to drive an inefficient prop. Another thing I did today was to make an annular shroud or duct for a test fan, 35mm dia. Haven't made the fan yet.

Stephen.
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Don McLellan
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« Reply #1329 on: February 24, 2019, 01:16:02 PM »

Beautiful flight Stephen.  On the last leg, it was unclear whether the trees were going to come into play.   Grin
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« Reply #1330 on: February 24, 2019, 07:51:55 PM »

That was a nice flight Stephen. I think the motor seems to be working better with the lower pitch. The model still has ample flying speed and the glide indicates that the pitch is not too low as well as the glide angle is quite good. Not a bad motor run time either.

John
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« Reply #1331 on: February 25, 2019, 03:12:40 AM »

Hi Don - it was unclear to me too, looking through the tiny camera viewfinder Smiley. I can't wait for the grass to grow a bit on the bigger field so I can use that.

John, those are interesting points. The motor has sounded a lot more buzzy and harsh in the last few flights - it might be simply damage from the number of times the model has smacked into tree branches etc. at full tilt, or perhaps it's the prop resonating or somesuch. I know that when I tried a steeper blade angle (20°) it ran much more quietly (but the model flopped around and found it hard to keep airborne for long). Yes, I think perhaps I was in the right area with 17° but must explore the finer side too, and will watch how that affects powered-glide angle near the end of the flight. It's so hard to make assessments outdoors because of changing weather. The powered glide phase is interesting because when I pick up the model and see how feebly the prop is turning I realise that it can sustain the glide much further through the capacitor voltage than I thought possible. I really think that if I can open up the turn from that steeply-banked pattern it will make a big difference, and although I only built this thing to get a feel for this supercap malarkey before delving into ducted fans, I'm now thinking there may be a niche for propeller-driven scale model subjects unsuited to rubber by their layout. I know that electric flyers will say "duuh, you just realized that?" but I'm really referring to capacitor power as that stuff with zombies and voodoos still doesn't grab me.

If the prop is bought to a sudden halt from a crash, esp. when there's still a lot of charge in the cap, does that damage the motor?

Stephen.
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« Reply #1332 on: February 25, 2019, 10:02:11 PM »

my first post... Grin

Built the cabaine structure for a Fokker DVII that I am scratch building.  it is my own design,  it is stand way way off kinda scale.  Semi Semetrical airfoil so I am calling it the DVII Sport. 

Pete
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MKelly
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« Reply #1333 on: February 25, 2019, 10:47:29 PM »

Cut a prop blank and started piling up balsa shavings.  Should have a prop ready in the next day or so...

Mike
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« Reply #1334 on: February 26, 2019, 01:58:03 AM »

Quote
If the prop is bought to a sudden halt from a crash, esp. when there's still a lot of charge in the cap, does that damage the motor?
It is possible that there the high current of a stalled motor  in those circumstances could burn the brushes/pit them. This would cause the brushes to arc more and that would make more noise.
It's also possible that the motor may still be over propped. However it is still doing enough revs to fly the model well on the low pitch setting.
I don't think I would go to a higher pitch from this point - in fact, I would consider slightly lower to see if it enabled the motor to rev a bit harder which would reduce both your current consumption and the torque - thus reducing the angle of the bank on the left turns.
A check of the current consumption with the prop would provide a better guide to how hard the motor is working.

[quoteI realise that it can sustain the glide much further through the capacitor voltage than I thought possible][/quote]

This and the soft power run down are attractions of capacitor power. It appears to make the model much easier to trim. They have a similar power run down profile to rubber, but at much lower torque and thus higher revs with consequent smaller props.

John
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p40qmilj
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« Reply #1335 on: February 26, 2019, 03:24:18 PM »

 Grin  finally got the p40 dimer together
 here are two pics showing progress

jim Grin
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« Reply #1336 on: February 26, 2019, 06:42:32 PM »

Flying along there Jim Smiley
John
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« Reply #1337 on: February 26, 2019, 07:09:31 PM »

Downloaded plan for Diablo Foamie.  Got it printed.  Still working on DVII Sport.  will be for a while.
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« Reply #1338 on: February 27, 2019, 12:47:16 AM »

Last night.  Cut new keel parts (and my finger - stupid boy) for the revised Horsa fuselage.
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Jack Plane
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« Reply #1339 on: February 27, 2019, 01:11:45 PM »

Was up at cock-crow to complete the installation of a new G-43BB in my Peanut Bristol Scout (test flights at Nijmegen last Nov proved it was underpowered with the G-28), with the intention of first outdoor trimming at the FF club field in today's fantastic weather.  It was running fine albeit with limited power on a gas charge, but unfortunately when I gave it a liquid charge something unpleasant must have happened (liquid entered the cylinder head?) as the engine now runs erratically with no real power at all!  Sad

I'm almost at the point of ditching the whole CO2 thing for this model, intended for KS at the Nats in April, and converting it back to rubber (i.e. its original design)!  Embarrassed

So, although model-less, I still decided to skive off work and went down to the field, chatted with the guys, and enjoyed watching Andy (abl of this parish) re-trimming his DPC Pfalz: https://photos.app.goo.gl/Q8wqwNV1ST5KtKxL7
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« Reply #1340 on: February 27, 2019, 03:36:27 PM »

Sorry to hear of the troubles with the Scout Jon, hope you get its sorted. It could just be debris in the engine valve ?? or frozen o rings ??

I too took advantage of the unseasonal weather and headed over to Port Meadow, Oxford.

Unfortunately Mrs Squirrelnet had the car for the day so I had to use my daily transport instead

Pic 1- meet the Rapid Model Transportation Device :-).. the downside is I have to spend the afternoon in leathers

A great afternoon's flying with some other OMFC members on the meadow

Pic 2 - ready for an afternoon's flying. I managed to cram two models on the Bike. An Rc assist Vic Smeed Coquette ( My mate Dave's Coquette is in the video) and my reliable old FF Rocketeer - a design from 1939 by Maurice Schoenbrun

There's a videos here https://youtu.be/bv52mr8QlSQ
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« Reply #1341 on: February 27, 2019, 05:30:19 PM »

Installed a GG nose button and built up one of Mike M's (ZK-AUD) freewheelers for the Wicko.  My soldering is anything but pretty, but it is solid...

Mike

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« Reply #1342 on: February 27, 2019, 05:51:26 PM »

Mint!

Love this model.
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DHnut
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« Reply #1343 on: February 27, 2019, 08:03:22 PM »

Jon,
      Do not give up on CO2. Liquid charges are a bit probmatic if you do not keep the tank below the motor when charging. I had this problem at the Nationals in August with the Comper until Andy Sephton pointed out the error of my ways. After that it was all go with 6 very consistent flights. Also be careful with O rings after CO2 ice has passed into the engine as it can nick the O ring. Also oil before a flying session helps. I tend to over oil as it ensures friction is minimised. The increasing of motor size is a good move as it is better to overpower and throttle down.
The flying site looked familiar but I cannot place it.
Ricky   
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Jack Plane
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« Reply #1344 on: February 28, 2019, 03:13:51 AM »

Love the Rapid Model Transport Device Chris!  What a great day for both aeromodelling and biking.

Thanks for the pep-talk Ricky.  I suspect that ice did damage the o-ring which I'll replace, but I also hope that the nylon seating itself hasn't been deformed.  The installation (of pipes, tank, motor-orientation) is almost identical to the G-63 in my Camel which is fine with a liquid charge, but maybe I need to re-think where the filler-valve emerges...?  Also, maybe I should only use sparklets rather than soda-stream.

The field is near Hungerford and is as perfect as it gets for both FF and RC.  Unfortunately the land has recently been sold and the new owners don't want the bother of a few quiet enthusiasts Cry so we're on the lookout for an alternative site.
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DHnut
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« Reply #1345 on: February 28, 2019, 04:23:15 AM »

Jon,
       Good to hear you are going to purservere with the CO2. The Sodastream cylinder is safer as sparklet bulbs can have small flakes of iron oxide in them that do not do the motor any good at all. The Comper filler valve exits undeneath the fuselage so I have to hold the model nose up as the tank is inclined at 45 degrees and is behind the motor, if I were to do it again I would make it more upright.
I did recognise the field, as I was flying the Comper, Piper Cub (CO2) and a Magister there in May and August as I was staying at Kintbury at the time. Thanks to the Club for allowing this as a visitor. Sad that the new owners as not as accomodating as the previous one.
Ricky
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« Reply #1346 on: February 28, 2019, 03:17:32 PM »

Still cutting parts for the second go at the Horsa's fuselage.
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« Reply #1347 on: February 28, 2019, 03:53:26 PM »

The Sodastream cylinder is safer as sparklet bulbs can have small flakes of iron oxide in them that do not do the motor any good at all.

I used to put a magnet on the side of the sparklet bulb in an attempt to attract the little flakes to the side of the bulb.  It worked for me.  At the time someone said it cannot work but had to change his mind later. 
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« Reply #1348 on: March 01, 2019, 12:53:30 AM »

Good looking prop and hub Mike K. Whose carving instructions were you following - the open book in your first post?
Very atmospheric site SN - not to mention your rapid transport. Not too rapid I hope the models are only supposed to fly after leaving the plastic box Smiley

John
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« Reply #1349 on: March 01, 2019, 02:50:18 AM »

Quote
Very atmospheric site SN

It's a great site. One of the few left where free flight flying, including power models, is permitted. It's a shame it's not used by more flyers.

Quick plug - https://www.oxfordmodelflyingclub.org.uk/flying-sites/

'Rapid transport Device' added a very nice dimension to an afternoons flying, it's a nice ride up to Oxford with the benefit of  filtering through the traffic when I get there .... shame I can't get any more models on it ;-)
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