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Design & Build FW 200 Condor / Syndicato

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onetenor24/07/2018 22:10:37
1809 forum posts

A landing light can made from a boat searchlight. I did have two more tips but forgot what they were just now.

onetenor25/07/2018 12:50:31
1809 forum posts

Here we are ! To ensure formers are the same both sides Draw half a former to a line Now fold the paper along the line and cut out the former through both pieces of paper. Unfold and you have a complete former. The shampoo in the bottles makes good spot/stain remover from mattresses and upholstery.Scrub in with a toothbrush and sponge out with a damp cloth or sponge. Mix the rest with your car shampoo or use as a shamp for the car.. Brilliant.

Robert Parker11/08/2018 09:10:17
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834 forum posts
1088 photos

Hi All,

New props ordered, only 1 in stock so I will have to wait until I get them, and now the weather turns.

Regards

Robert

Robert Parker18/08/2018 14:46:37
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834 forum posts
1088 photos

Hi All,

Props arrived during the week plus a new 4s 5000 battery pack.

I have done some static thrust tests with my watt meter attached, below are the results

3s original 7x5 2 blade props 2lbs thrust drawing 15.8Amps and 191 watts = 27watts/lb

3s with 8x6 3 blade props 2.6lbs thrust drawing 27Amps and 315 watts = 45 watts/lb

I had to trim down the new inner props to 7 3/4" to give clear the fus

4s original 7x5 2 blade props 3.2lbs thrust drawing 25Amps and 400 watts = 67 watts /lb

4s with 8x6 3 blade props 4.8lbs thurst drawing 42Amps and 695 watts = 99 watts/lb

The new battery pack is 4ozs heavier than the 3s which brings the new weight up to 7lbs 4ozs.

So with the new battery and prop set up the power gain is 72 watts / lb. I'm so glad she did not take off on that maiden flight.

I would welcome any comments on the above results as I'm still learning this art of electric flight.

Regards

Robert

Edited By Robert Parker on 18/08/2018 14:49:46

Edited By Robert Parker on 18/08/2018 14:51:26

Edited By Robert Parker on 18/08/2018 14:51:59

Robert Parker08/10/2018 19:24:44
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834 forum posts
1088 photos

Hi All,

Went flying yesterday with the intention of maidening the Condor with the new battery pack and prop combo.

Pre-flight checks - done,

Range check - done,

Photo shoot - done.

my condor 1.jpg

my condor 2.jpg

my condor 3.jpg

Lined up and ready to go.............

my condor 4.jpg

.......this only took a few seconds from the previous photo and things don't look to good here.

I would like to thank fellow club member and examiner Darrel for the photos

So what happened to get to this point, well I gradually opened up the throttle and she started to roll straight and true opened up to get the tail up which she did then in a instant as soon as the wheels left the ground she went into a tight loop I don't think I had time to react as it all happened too quickly.

I am not sure what the cause was. I re-checked the CoG after fitting the new battery. The CoG position was calculated from the net using rcplanes online cg2 using a wing with two swept wing panels.

Motors, no down thurst, 2 motors on the right wing 2 degrees side thrust.

props all rotating same direction.

The CoG position and or the tailplane incidence are in my mind but I would welcome any thoughts

dsc05129.jpg

Extensive damage to the fus totally gutted

dsc05130.jpg

Appart from the wing mounts and the slit in the wing sheeting the wing seems to be salvagable

Regards

Robert

Martian08/10/2018 20:00:05
1964 forum posts
934 photos

Robert that is devastating I really feel for you sad

McG 696908/10/2018 20:09:13
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2344 forum posts
974 photos

... ooh, sjeesh, Robert. surprise

Don't really know what to say after all that lovely dedication you had...

Hope that at least the wing will be salvaged. question

'Matata' here for sure

Chris

Paul C.08/10/2018 20:38:39
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482 forum posts
112 photos

Sad news Robert I have followed your thread from the start, although the fuselage is extensively damaged a have seen a lot worse repaired give it a day or two and take another look at it .

C of G sounds as though it may be the main contributor to the crash but it also looks that the elevator still had a lot of up in the last photo or it may just be my eyes.

Hope it is repairable Paul.

Erfolg08/10/2018 22:44:41
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11067 forum posts
1077 photos

It could be a CG issue. As we are constantly reminded, it is best to start with a forward CG and be safe. For an airliner, a soggy pitch response is not really an issue, if the stability is improved.

It could also be an issue of longish and damp grass, slowing down the acceleration, and possibly limiting ground speed. My PT 19 was a pig to get of the ground with limited power and poor ground. When it finally could be coaxed into the air, it was often nose (high) up, with limited air speed, getting ready to re-kit itself. Re motored the issues just disappeared.

I would stick it back together, forget abut the finish and try again, with a set up you think may be better. Once flying, then I would start thinking of a nice rebuild and a pretty finish.

Ken Ball 109/10/2018 00:46:10
9 forum posts

Sorry, don’t know what else to say. Looked really good and should fly as good. I would follow the advice from above and let it rest for a day or two, I kick rocks for a couple of days when I rekit one,

Ken Ball

Indiana USA

Dwain Dibley.09/10/2018 00:52:50
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955 forum posts
938 photos

So sorry to hear of the demise of such a beautiful model Robert, but..............it looks repairable to me.

The secret is to leave it alone for a bit, to mourn, and then to get stuck in with the rebuild. The consensus seems to be C of G, and Erfolgs advice seems sound re the rebuild and test, then get the finish sorted.

When I built the de'ag spit I flew it before starting the finish due to people believing it would not even get off the ground.

All the best, what ever you decide to do.....wink

D.D.

Erfolg09/10/2018 11:34:31
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11067 forum posts
1077 photos

A hand launch could be a safer bet, if you have some one in the club who has a reasonable technique.

Incidents as you have experienced, have many of us thinking about similar types of personal experiences.

I do not know the answers, although I can relate issues that some of my models have or continue to have. The Slingsby T67 has a long take of run, when the the grass is anything but very short. It even suffers from damp grass slowing it up. I think the issue is at least partially down to small, scalish type wheel size. The other issue i think is the model sit on the ground, the wing should be lifting being only a degree or so below the 0-0 line. When the tailplane eventually lifts the nose wheel of the ground, the model seems to be traveling quite fast. Yours being a tail dragger the same issue should not be present, although longish grass and wet ground conditions could be slowing your model up. The temptation is to inadvertently to put more up in than is desirable, together with a transitional airspeed, it can be recipe for disaster. I am guessing that you do not have an abundance of power, as many models now have, that leap of the ground having moved 100mm.

My PT 19 has one other issue that has to be managed. The UC is wire that came with the kit, although now used as a std. Torsion bar set up. The wire is not stiff enough to have the resistance i would like. It can be easily induced to move about 70mm total travel at the wheel. When the grass is tufty, this movement seems to consume a lot of energy. Given the cycles per minute can be quite high it could explain where a lot of my power still disappears to. Given that Work Done = Force * distance moved through. It could relate to quite a chunk of watts. Is your UC stiff?

Robert Parker09/10/2018 18:51:22
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834 forum posts
1088 photos

Thank you all for your replies and sound advice. I will certainly be kicking a few stones for a while and a re-build is to be done.

As for power she had loads this time 99 watts per pound or 695 watts in total.

I too had reservations about the wheels and grass being only 3", the grass was shortish and the ground conditions were fairly good. I must thank my fellow club members who earlier this year spent time digging new drainage channels which have really helped the patch as well as the moss removal.

The u/c is stiff the only give is the 5mm wire pins from the units to the spreader bar for want of a better name which is only 1" long. I have not looked closely at the wreckage yet- too early.

Yes there does seem to be a fair amount of "up" elevator in the last photo.

The CoG is certainly a good starting point for re-calculating, not straight forward with a double swept wing, possible an error here.

I'll keep you all posted on developments

Once again thank you all for your support and encouragement.

Regards

Robert

Erfolg09/10/2018 21:25:00
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11067 forum posts
1077 photos

100 watts per pound is not bad for a civilian type model, that is once flying. It is getting the thing reliably into the air that can be an issue. My PT 19 had from memory just +100W. per lb, the take offs were marginal. Strangely, the left swing was quite pronounced, when compared to increasing the wattage by I think 50%. The swing reduced significantly and transition from running along the ground to flying is now authorative. No more struggles, and giving the (justified) impression that I am not the most skill full of fliers.

I suspect that ball park estimates as to what the watts drawn is necessary, is not as valid when 4 motors, with smaller propellors, and more area of wing and nacelle to reduce efficiency.

I would try a hand launch, just to get the information as to how effective the power plant is. To see if it flies like a small glider.If so, then I would be looking for more power from the motors, some how, to provide that reassurance that the power provides, at take off.

Robert Parker09/10/2018 23:26:55
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834 forum posts
1088 photos

Thank you Erfolg, I may try the glider launch when the repairs are complete.

Regards

Robert

trevor wood 210/10/2018 00:20:17
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22 forum posts
21 photos

Robert, l agree with the recent posts that that the likely cause was a CG that was too far aft. In your early posts you describe the model having a 72" wing span, and from the inverted plan view photograph in your back garden, I estimate the wing root chord to be about 10.5". In a later post I recollect that your calculations showed the CG should be at 124mm aft of the LE.

If you ignore the slight sweep back of the outer wing panels and assume a "safe" first flight CG to be at or about 25% MAC, yours should have been at about 66mm aft of the wing LE. If you want to include the affects of the slight outer panel sweep back (or are feeling particularly brave) then you might consider going to 75mm aft of LE for the next "first flight". A CG position at 124 mm would be in excess of 40% MAC, which easily accounts for the vicious pitch up you encountered.

PS. I wouldn't even consider trying to persuade someone to hand launch a 7lb, 6ft span, low wing, 4 engined scale model for a first flight.

Erfolg10/10/2018 12:17:46
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11067 forum posts
1077 photos

Hmmm, the model is quite a bit heavier than I thought. I have assumed an av, chord of 9.5", which is probably optimistic, which gives a wing loading of 25 oz ft^-2. I have a few models slightly less loaded in that region.

190d paint1.jpg

190afin1.jpg

both are at 22 oz ft^-2. The difference is that they are @ 4lb and 500w at launch.

The problem could well be a combination of small issues, that in themselves are trivial.

The PT 19 is a case in point, where it was initially destined for the back of the hanger, due to the terrible take off regime. Add much more power and now flies every week, in some pretty awful conditions, which is typical here. This model suffered severe pitch up, when the power was low (246w), due to trying to coax it off the ground. It now is at 476W, now the speed builds very well, requiring just a small amount of up to unstick. Another 4 lb model.

wp_20170228_09_51_04_pro.jpg

Another case is the PM Cassutt. It was initially flown without a UC hand launched, with the CG at the PM 25% (as per plan). I then added a UC, which required a few changes. The plan had been lost, and I forgot the CG position and it was not marked. I moved it to 30%, the best pilot in the club (he has just won the club aerobatic comp) found it a nightmare just getting on the ground, after being everywhere other than where intended. PM consulted, CG back @25% and it is a pussy cat. Now flies every week.

wp_20170413_13_46_40_pro.jpg

 

 

Edited By Erfolg on 10/10/2018 12:18:09

Piers Bowlan10/10/2018 13:07:16
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1462 forum posts
41 photos

So sad to see a beautiful model end its maiden flight this way, commiserations Robert. Finger of blame pointing to C of G issues as a possible culprit by several posters. Just to ask the obvious, presumably the operation and reliability of the elevator servo has been comprehensively checked by now? No doubt when you were on the downside of the loop you were instinctively pulling hard on the elevator which accounts for it's position in the photo. The fuselage damage looks bad, although a repair appears quicker than a new fuselage. Good luck.

Robert Parker10/10/2018 23:47:08
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834 forum posts
1088 photos

Hi All,

Trevor you are very close with your estimation, it is actually 11". Those figures do make some sense.

I have taken a look at my calculations and feel that I it was out. We had a club meeting tonight and it was talked about in detail and the CoG may have been a cause but also / as well the tailplane incidence could also contributed or a combination of the two or other factors waiting to be found.

Erfolg, some nice models you have there, Once I make a start on looking at the debris and assess if anything could have contributed to the unscheduled arrival.

Piers, I have not looked at the model since Sunday. I will check all of the servos. Although all new that does not mean perfect. If I did try to pull out of the loop it was by instinct as it all happened too quickly and was all over in a second.

Regards

Robert

Erfolg11/10/2018 09:22:43
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11067 forum posts
1077 photos

I guess you set the tailplane to the 0 - 0 line of the wing section? If so I think you can safely eliminate tailplane incidence.

I assume that the nose section has just broken of? On that basis strapping the fuz together on a temp basis should not be to much work.

I do not know about how you feel, I personally tend to see these incidents as a challenge, providing as much self satisfaction smugness, as a straight forward first flight, once the solutions are found and implemented.

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