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Sep 16, 2019, 08:37 AM
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mustangwally's Avatar
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jofro :- [But, with the amount of work you going to put into this project you are better off doing it all the way, with the retract landing gear and use the best power unit your money can buy.
It's going to be too heavy for the El-cheapo 90mm fan unit.]

As I remarked before, too many model TSR-2s have bit the dust because of retract problems so retracts are definitely OUT. The fan can be taken out as there are removeable 3mm semi diameters held in place by the split formers FF14 and FF15.

I shall charitably take your remark about my 'El-cheapo' fan as a challenge, it produced 2.8 kg of thrust on test with the project ducting , not far behind a Wemotec Midi Evo 90mm fan unit so it's not yet a foregone conclusion that it won't fly.


Ianda :- There should be a fair bit of sheeting, the front fuselage is more or less slab-sided except for the roof and cockpit. The rear fuselage is more problematical and I can see planking being necessary there and around the intake / wing interface. However, it's no worse than the Spitfire, that was like a marathon.
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Sep 18, 2019, 04:25 AM
jofro
Quote-As I remarked before, too many model TSR-2s have bit the dust because of retract problems so retracts are definitely OUT.

I see no reason why the retracts or even simple fixed landing gear should be the reason of biting the dust of any model if proven, proper power unit is selected.
You will only find out about the true thrust figure in fully completed model, and with your 6S set up you will be disappointed if you rely on your test stand only. So it will be interesting to see how you end up.
I got no idea how fussy you are about the true scale, but scratch building a model leaves you always open to bit of improvement innovations, like slight enlargement of the flying area to reduce the wing load. Good luck with the project, seem like you know what you are doing.
Cheers.
Sep 20, 2019, 03:42 PM
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mustangwally's Avatar
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Not a lot of progress over the last few days having been waiting on a Hobbyking parcel to arrive. In the meantime I've done a bout half of the basic planking and fitted the motor back in place with the leads led out to the ESC, (must check motor rotation direction). At the moment the plane balances half an inch forward of the fan blades so I have decided, perhaps prematurely, to make the battery access between formers FF7 and FF9 instead of FF6 and FF8 bringing the flight battery slightly nearer the C of G. I included half a dozen wheels in the HK order as I intend to try and make the launch trolley look like the actual undercarriage, nothing like faking it on the cheap.
Sep 20, 2019, 03:54 PM
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turbonut's Avatar
It looks good..
Latest blog entry: In flight
Sep 20, 2019, 09:04 PM
jofro
Quote:
Originally Posted by mustangwally
Not a lot of progress over the last few days having been waiting on a Hobbyking parcel to arrive. In the meantime I've done a bout half of the basic planking and fitted the motor back in place with the leads led out to the ESC, (must check motor rotation direction). At the moment the plane balances half an inch forward of the fan blades so I have decided, perhaps prematurely, to make the battery access between formers FF7 and FF9 instead of FF6 and FF8 bringing the flight battery slightly nearer the C of G. I included half a dozen wheels in the HK order as I intend to try and make the launch trolley look like the actual undercarriage, nothing like faking it on the cheap.
Shame you didn't do your air intakes much more rounded, they are too edge sharp, it will give you poor performance. With proper intakes you might get close to 1/2 a kilo extra thrust from 90mm fan unit.
I had some fun catapult launching my old "Hawk" at the home Club yesty in nice conditions, bellow is short footage of one of the catapults to give you an idea how easy it launches with 1 to 1 thrust pull release, this is 6S set up.
2019 0920 173021 031 (2 min 40 sec)
(Catapult action)
Sep 20, 2019, 10:58 PM
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AntiArf's Avatar
Quote:
Originally Posted by jofro
Shame you didn't do your air intakes much more rounded, they are too edge sharp, it will give you poor performance. With proper intakes you might get close to 1/2 a kilo extra thrust from 90mm fan unit.
I had some fun catapult launching my old "Hawk" at the home Club yesty in nice conditions, bellow is short footage of one of the catapults to give you an idea how easy it launches with 1 to 1 thrust pull release, this is 6S set up. https://youtu.be/i65rFlvR5Xc (Catapult action)
Not it's not a shame. It would be a shame and look ridiculous with off scale, heavily rounded intakes and features like "painted" glass. Built plenty of scale jets with scale intake lips with adequate performance. The gains are irrelevant if built to good known spec for good performance, which is what competent scale builders do. Why the need for catapult launchers? I build scale models close to that size that are easily hand launchable (still with retractable gear) that fly well on a 3s-1800 at well under full throttle. https://www.rcgroups.com/forums/show...ht-video/page7
Sep 21, 2019, 04:19 AM
jofro
Quote:
Originally Posted by AntiArf
Not it's not a shame. It would be a shame and look ridiculous with off scale, heavily rounded intakes and features like "painted" glass. Built plenty of scale jets with scale intake lips with adequate performance. The gains are irrelevant if built to good known spec for good performance, which is what competent scale builders do. Why the need for catapult launchers? I build scale models close to that size that are easily hand launchable (still with retractable gear) that fly well on a 3s-1800 at well under full throttle. https://www.rcgroups.com/forums/show...ht-video/page7
EDIT- Sorry, I didn't mean to offend, only trying to help OP, asking for an advice or tips on the subject. I'm rather used to of my followers jumping in after my posts just to poke and provoke. This is not a "Scale model forum", but "scratch built one" and this build certainly not for 30mm, EDF, 3S/1800mA powered floaters to compare to.
Last edited by jofro; Sep 24, 2019 at 03:26 AM.
Sep 21, 2019, 05:59 AM
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Ianda217's Avatar
There's no need to be rude.

If you're building a scale model, then build it scale. Think how ridiculous an E.E. Lightning would look with a rounded intake.

Also, Mustangwally's ducts were tested for performance before he started the build. Whilst more thrust might be available by deviating from scale, there is adequate thrust from his ducts (sharp inlet, oval outlet and all) to power his model so long as he achieves his target weight.
Sep 21, 2019, 01:23 PM
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mustangwally's Avatar
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OK guys, thank you AntiArf and Ianda for your constructive comments, I'm beginning to realise why we don't see other flyers in jofro's pictures.

I'm just back from Ullswater after a fine day's water-plane flying, rather gusty wind at times but sunny with very good company. A great variety of models taking part and plenty of good humour. Just why I enjoy this hobby so much.

I have been playing around with various combinations of bungee and trolley with my TSR-2 'mule' and I have decided to go with the union1 set-up using a two wire pull system from the bungee, (see page 1). This gives me plenty of 'faffing' time pre-launch to get set up without getting in anyone's way. Thank you everyone for your help.
Last edited by mustangwally; Sep 21, 2019 at 01:25 PM. Reason: Capitalise 'union1'
Sep 22, 2019, 05:33 PM
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mustangwally's Avatar
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To fill in the periods of intense frustration / boredom while waiting on planked sections to dry I have been thinking about how to achieve a matt finish on a film surface. The real thing has a sort of matt sheen finish, 'anti-flash white' or something, which I would like to replicate. I applied some white Hobbyking film to a few test pieces and tried several methods to dull down the high gloss finish with varied success. First off I tried Cif, (slightly abrasive household cleaning creme), with almost no noticeable effect for quite a lot of effort. Then I used a green scouring abrasive pad with soap and water again with little success. Next I used some 600 grade carborundum paper also with soap and water, this seems quite promising all be it involving a fair bit of time and effort. It strikes me that there are probably plenty of modellers out there with direct relevant experience of solving this problem, (just struck me, how about some of that coarser polish they use to buff cars paint???). Anyway, ideas welcome thanks.

Oh, here's a couple of pics of the trolley
Sep 23, 2019, 07:34 AM
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Larry Dudeck's Avatar
How do you plan on keeping the plane on the dolly during launch?
My limited experience with dolly launching was a failure mainly because I had no means of holding the plane on the dolly. The plane/dolly combination must exceed stall speed before the plane can be released. Otherwise it will crash.

Another potential problem I see is the bungee launch. Typically you will have about 1.5 seconds from the time you step on the pedal and the moment of truth. The plane, if balanced properly, flies. If not, it crashes. Guessing a stall speed of 25 mph, the plane/dolly accelerates to flight speed very quickly and if the plane is not firmly attached to the dolly, it will slide off.

in addition to keeping the plane from sliding backwards off the dolly while accelerating, how do you plan on keeping it from bouncing up and down. Unless the flying field is putting green smooth, it will tend to bounce.

I'm not trying to dissuade you from dolly launching. I'm just relating my experience with the method. My efforts ended in a busted airplane.
Last edited by Larry Dudeck; Sep 23, 2019 at 07:35 AM. Reason: Spelling
Sep 23, 2019, 10:12 AM
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mustangwally's Avatar
Thread OP
Hi Larry, there is a dual connection to the bungee, one wire goes to the front of the trolley and the other to a hook underneath the plane, the plane hook resting in the slot on the top surface of the trolley. This means both the trolley and the plane are being towed by the bungee the drag on the plane seems to keep it in line but there are small foam blocks, (which will be fitted to the trolley after the plane is skinned), to initially align the plane. I plan to trigger the launch with some power already on at rest, say 25 - 30%, then smartly apply full power as the bungee accelerates the plane. On tests with the 'mule', the plane clearly lifts off so flying speed must have been reached, it accelerates past the by now slowing trolley and its hook disengages from the bungee connection. If the plane doesn't rise off the trolley then it must be under-powered so would never fly whatever method I use.
Sep 23, 2019, 10:32 AM
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mustangwally's Avatar
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Larry A picture is worth a thousand words.
Sep 23, 2019, 08:19 PM
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Larry Dudeck's Avatar
That seems like a simple but elegant solution, the very best kind. I like it.
Sep 24, 2019, 03:04 AM
jofro
Quote:
Originally Posted by mustangwally
OK guys, thank you AntiArf and Ianda for your constructive comments, I'm beginning to realise why we don't see other flyers in jofro's pictures.

I'm just back from Ullswater after a fine day's water-plane flying, rather gusty wind at times but sunny with very good company. A great variety of models taking part and plenty of good humour. Just why I enjoy this hobby so much.

I have been playing around with various combinations of bungee and trolley with my TSR-2 'mule' and I have decided to go with the union1 set-up using a two wire pull system from the bungee, (see page 1). This gives me plenty of 'faffing' time pre-launch to get set up without getting in anyone's way. Thank you everyone for your help.
TX mate, but don't forget my advice and helpful tips on bungee /catapult launching.


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