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Member postings for Dave Cooper 3

Here is a list of all the postings Dave Cooper 3 has made in our forums. Click on a thread name to jump to the thread.

Thread: Fan /Model match ?
17/12/2019 23:05:24

Hi E.D. That price sounds more than reasonable if it's a good unit.

Just been on Jet Hangar's site ( and they advise 80-100% of Fan Swept Area (FSA) for inlets and 70-80% for outlet.

They do warn about cheap Chinese clones of their product, a number of which have failed in service....You pays your money....etc.

There's a formula for calculating FSA under the "EDF Rules" heading. It does look like it's a compromise between take-off power and top speed. As I'll have 2 inlets and one outlet I'll have to get the calculator out !

Hope to get bench testing or two other projects to finish first.


17/12/2019 10:43:27

Good to hear the thrust should be OK. The "Banggood" 12 blader looks good - couldn't see a price on the ad' though.

As my model is EPP I was just wondering if this would have some sound absorbing qualities. Presumably, I'll have to conjure up some form of thrust pipe as well ? Rolled ply /balsa sheet ?

I'll have a look at the Youtube videos on balancing as well...


15/12/2019 20:50:46

Yes, thanks for that John - quite a few of our sites are noise-sensitive. I will test the unit and see if the neighbours complain first !

A '12-blader' may be more appropriate anyway - more efficient ? extra thrust perhaps ? A real learning curve for me...


15/12/2019 14:59:45

Thanks for the reply E.D.

A trip to the workshop has now revealed :

Fan: 6 Blades - 75mm diameter

Motor - 3500KV (QF 2827)

Fuselage width - 70mm and depth 100mm. (measured at approx. C of G). Width could be made wider with air intakes to accommodate the fan unit

Weight : approx. 2lbs (without LiPo and without fan unit). I would imagine a 6s may be needed to give reasonable flight times ?

The model was designed as a PSS glider, so, an EDF version would need some mods ! I will bench test the fan soon to see how it sounds /performs...


15/12/2019 00:03:49

Hi, I have recently acquired a brushless EDF fan unit and a PSS Aermachi model at an auction.

I think the fan unit is an '8-blader' and the jet model is about 51" span. I was intending to fly it PSS to start with and, later, convert it to EDF.

What data would we need to decide whether it was suitable for conversion or not ? I have in mind :

Model weight, KV rating of the motor, fan diameter, fuselage width /depth at the CG for starters.....anything else ?

Thanks for any assistance (only previous 'jet' experience is with "Jetex" models as a young lad !)


Thread: Glossary - your forum needs you!
24/12/2018 11:33:12

Castor Oil - the word superceded should be spelt "superseded" (from the word supersession)...I got 'picked-up' on this whilst at Airbus, by the Quality Assurance Team, writing the requirements spec' for the A350's wing !

Compliments of the season everyone...


Thread: Setting a status
27/11/2018 15:54:10

All very mysterious....status, profiles, public, friends, clicking etc etc. Tutorial anyone ? (I'm not volunteering by the way !).

Thanks to all the contributors so far...

Dave (for testing purposes 'status' = "Improver Mark 1" sadly, no 'friends' as yet)

27/11/2018 08:36:01

I don't think I've ever seen a member "On Line" notification on this forum, but, will pay more attention in future !

We live and learn it seems....


26/11/2018 21:04:00

OK thanks eflightray - I'll try something....

26/11/2018 19:26:14

If there's a Moderator around, the posts are now repeating whilst the 'post counter' does not seem to be incrementing

Even more confused of Wiltshire.....(sorry to be a pain everyone !)

26/11/2018 19:18:45

Ron - such as what exactly ? Do I just make something up, or, are there 'standard' status's (stati ?). Where else does it appear on the forum once set ?

Confused of Wiltshire...!

26/11/2018 17:29:00

Just found the blank "Edit" box....but, really, none the wiser ! Allowable settings ???


26/11/2018 17:24:14

Under "My Friends" on the Forum home page it tells me to 'set a status'...

How does one actually do this ? I can't find any relevant help anywhere on the forum or am I becoming myopic ?


Thread: PSS Jet Provost
23/11/2018 19:57:45

Hi All - a quick update : Having just finished working with the builders to level my garage floor and applied the (very expensive floor paint !), I can now get my modelling projects back on track...

(Andy mentioned an interest in motorsport in an earlier post - so, the level floor is for my 10% wind tunnel. This to give me key lift /drag data for a Le-Mans style sportscar that I'm building. Also, it now gives me reliable 'datums' to take chassis measurements from).

So, finally dug out the plan for the JP and it's a Roger Howells' design for a 40-size power model. About 47" span, and, prettymuch-true-to-scale. If I can keep the wing loading to a reasonable level, it might just work as a PSS job. Wing section looks OK(ish), but, yet to verify the actual section. Will probably need some tip washout to make it nicer nearer the stall plus some lead up front in lieu of motor /fuel etc.

Anybody tackled anything similar ???


Thread: ESC not working?
20/11/2018 08:56:10

I think the worst-case scenario is late cut-off of the BEC. This happened to myself and a friend when we built the HobbyKing Phoenix 1600 electric glider (this is our club's chosen one-make competition machine).

The motor is a modern brushless with a programmable ESC and a 2s LiPo. His model crashed (fortunately without too much damage) when he ran out of radio contact and he immediately phoned me to check mine. The motor and ESC are supplied with the kit. I tested mine on the bench and had a max.of two or three control movements just as the motor was running down. None of the other kits had this problem and came from an earlier shipping 'batch'.

After some more bench testing, HobbyKing supplied a replacement ESC...the first job was to 'calibrate' the ESC to the motor, the second was to set the prop brake (using their instructions). Next, I took a LiPo that was down to about 50% capacity and timed a 'dummy' last flight until I was satisfied that I had enough range and control movement to safely land the glider.

The moral of the story, IMHO, is to know the limitations of each model /installation and use planned flight duration times if there is any doubt...Happy flying everyone !


Thread: PSS Jet Provost
12/11/2018 17:34:57

Thanks for the advice Andy, as a PSS beginner I'll try and do a light build on this one.... ( for some reason my tails often come out a little over-weight !).

The main local slopes are about 600' high and, for PSS, the experienced guys tend to fly in winds of 10-20+ mph. As you say 'brick-lifters'. Nevertheless, I think 15-16 oz/sq ft is a good target for me to aim at.

BTW Andy / Phil I'd like to have a look at Ron Collins's plan - any idea of size and where I could get one from ?

Cheers for now,


10/11/2018 16:16:29

Hi both - thanks for replying :

Phil - Yep, a straight scale-up is very tempting. We've got the builders in at the moment and all my modelling stuff is up in the loft for safe keeping ! But, I was thinking around 4 foot span and about an 8" median chord. I'm not a very efficient soarer yet and I was thinking that the extra wing area might help me to stay aloft in more marginal conditions.

Andy - yes, I have a Capstan model (E205) of around 6' span and, from memory, it has about 1-2 deg's of tip washout. Not maiden'd it yet but others report that it flies nicely rudder /elevator and very well with ailerons (I've just finished the conversion).

I was wondering if the washout on the JP could be 'blended' into the tip tanks to make it look more scale-like ? I don't think the plan is 'Ron Collins' but, it is a Mark 5. Target weight was around 3-4 lbs if I remember the magazine article correctly. Does this seem ok for wing loading ? Some of our club members have built yours and speak very highly of it's performance.


10/11/2018 09:03:33

Hi All

Quite fancy a PSS Jet Provost design /build for this winter. Had a look at the Andy Blackburn design (subject of the Mass Build ?) but this is rather small at around 36" span.

Have now sourced another plan plus some scale drawings which look rather promising....not sure about the plan's wing section though which seems to be a member of the NACA semi-symmetrical family. On the slope, I'm wondering about a Selig 7055 or Eppler 205 /374 section ?

I'm after a fast(ish) model with good penetration and energy retention. Probably 'stand-off' scale in terms of detail - light, but strong airframe which can be ballasted up for different wind strengths. I have some carbon, Kevlar, grp and Liteply available (plus good-old balsa !).

Thanks for any assistance from the PSS experts...


Thread: 1/6 Westland Whirlwind
04/11/2018 22:36:15

Hello Timo - you are making great progress ! I read Harold Penrose's biography many years ago....did you know that he designed his own glider ? There was a Nexus /Traplet plan available at one time. I was interested in building it as a future project (I like unusual scale gliders for slope soaring).

A couple of questions if you don't mind :-

1. Where did you get the 'Japanese Saw' ? It looks really useful. I haven't seen one advertised by anyone in the UK.

2. What radio are you planning to use ? Will there be a special arrangement to synchronise the motors /props to resolve any adverse yaw tendency ? Special ESC(s) linked to micro-controllers ?

Looking forward to seeing a possible video of the early flights maybe...


Thread: Which Set Should I buy
01/11/2018 23:25:45

Hi again Eric - just a few final comments from me. I'm basically a Futaba man (35 MHz) and I think their '2.4' spec's are very impressive. The problem for me is I will have 5+ models on the go next year, so, Rx cost comes into it very strongly and I don't want to disturb each installation to swap out a trusted Rx every time.

I read a tech' review on Aurora 9 the other day and it seems there may have been an issue with 'dead-spots' at the extremities of stick travel. This may have been fixed now, but, worth checking out. (potentiometer mis-alignment ?)

Taranis - this is most likely my new route for 2019 - a 3-metre, vintage, scale glider. I can put you in touch with an "Open TX" expert who will talk you through a complete set-up over the phone. BTW their Limited Edition Tx now has 'hall-effect' sticks - beautifully smooth when I tried them last week !


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