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Member postings for Engine Doctor

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

Thread: Fan /Model match ?
15/12/2019 11:17:15

Hi a 56 inch model will probably need an 80 or possibly a 90 mm fan , Do you know what the recommended battery is for the fan i e 4s or 6s and capacity then you will have a starting point to work out the balance/CoG and weight etc . It will also pay dividends to balance the fan, see you-tube , as a smooth running fan not only sounds much better but produces more thrust due less power being absorbed by the vibrations of an out of balance fan .

Try running the fan up before stripping etc as it might be a dynamically balanced unit.

Hopefully there will be more knowledgeable EDF build designers along to help. I can only offer what I have gleaned from messing about with fan models .

Good luck and let us know how you get on .

E.D.

Thread: Judder on all servos with DFT module
15/12/2019 10:48:39

Re the jerky or stepping servo action with FrSky radio . Friend in club has just found out that by holding the Fail-safe button on the Rx down for about 6 seconds when turning on changes the frame rate from a higher rate for digital servos to a lower rate for analogue servos . He said its seemed to have cured the problem . Hope this helps anyone else who has the problem.

Thanks for the help and suggestions .

E.D.

Thread: Valve work
13/12/2019 10:41:58

Hello Wilco. The originals will be fine . I usually anneal them by heating before refitting . Be very careful if you try this as too much heat can destroy them . If in doubt just clean and refit them . Dont use any silicone or gasket paper it will do more harm than good .There may be one or two gaskets/shims the diagram shows two but just refit the same that came out . If I'm stuck for a head Gasket or shim I cut one from annealed Litho plate . Also Be careful not to over tighten the head bolts as once a head is distorted its a throw away job.

Hope it all goes well

E.D.

12/12/2019 16:27:47

Hello Wilco . When you say head gasket do you mean the Cylinder head to the cylinder joint / If yes then the gasket here is a thin Aluminium washer there may be two . If you mean the rocker cover that cover the valves then then there is no gasket need or fitted . Some FS engines like YS need a rocker cover gasket but the ASP don't have any pressure in the valve gear and the cover is just to keep the dirt out .. Os engines have a gasket fitted to the rocker cover but its not really needed .

There is no oil supply to the valves or rockers and they should be oiled after every few hours running.Also apply a few drops down the push-rod tubes to lube the tops of the cam followers . A good quality mineral based 2 stroke oil is fine provided it doesn't have any Castor oil in it

Thread: The Gov't, CAA, BMFA & UAV legislation thread
12/12/2019 15:53:36
Posted by Gavin Mack on 12/12/2019 13:39:51:

Not sue if this has already been discussed but if your operator ID is on the outside, then anyone could take your operator ID and put it on their drone or plane, fly it and possibly crash it near an airport etc. You would have difficulty proving you weren't flying. Although more complicated each plane should have a unique number displayed on it, linked to an operator id which is kept private.

Be careful what you wish for ! The powers that be make a pigs ear out of the present set . Imagine what it would be like if we had to register each model ?

Anyway the number doesn't have to be visible it clearly states your number has to be IN or ON a model . Mine will all be IN the model

Thread: Bespoke water slide decals
12/12/2019 15:43:55

The ink jet water slide paper may have improved over time. I used it when it came out some years ago and it took the print very well but the adhesive was very poor and the transfers kept peeling off when put onto Lightspan unlike the transfers we used when we were kids that really stuck. Have used the self adhesive inkjet clear and metallic with good results

Thread: Buying LiPo`s
11/12/2019 13:24:52

You could also try Rapid RC Justin keeps a good range of lipos in stock .

Thread: Judder on all servos with DFT module
10/12/2019 15:26:52

Thanks for you input Brian .

hello Peter yes not a problem worked that one out .

Thanks

E.D. (Phil)

10/12/2019 11:09:17

Hi Mike The Tx is a FF9 Super . The judder might better be described as stepping? they go move at an inconsistent speed hard todescribe

Alan have tried binding in telemetry and non telemetry modes the Rx binds ok in either mode and the servo response is better/smoother in telemtry mode .

Peter . we will try binding using the jumper method . It currently binds in either mode using the F/S button but will try the binding plug and see if any improvment

Thanks for all the input . We intend to go to the flying site when its a bit drier and try range checking and also see if some distance between the Tx an model changes anything.

Will let you know the outcome

09/12/2019 13:44:50

Thanks Peter I'll pass that on

09/12/2019 11:59:04

Can anyone shed any light on the following ? I recently obtained a FrSky DFT Futaba Tx module . I don't need or want any telemetry and am using a Vr8 11 Rx

Have set the switches on the back according to the instructions for use with this Rx , Binds instantly but all servos judder as if the frame rate is wrong . I have checked back on much earlier post and there were some dodgy modules in early batches. This one I was assured is from the later batch so in theory should be ok . Were there any fixes found ?

Thread: Can I have two Life batteries powering my Futaba receiver?
09/12/2019 08:58:00
Posted by Piers Bowlan on 23/09/2018 11:47:30:
Posted by Engine Doctor on 23/09/2018 11:31:09:
Posted by Allan Bennett on 22/09/2018 21:10:21:

A simple way to prevent two separate power sources interfering with each other is to simply install a Schottky diode (with a suitable amps rating) into each +ve battery lead before they go into the Y-plug or into two separate receiver inputs. Then if one fails in some way, the other will not be able to feed power into the duff one, but will continue to power the receiver. I've got such a system in several of my aircraft -- fixed wing and helis -- using BECs rather than batteries as the power sources. I've also added an LED to each 'channel' to give an indication if one of the power sources has failed.

yesThats my preferred method too. I also use a separate switch for each battery fitting the diodes into a "y" lead between the switch and Rx .

OK, so to ask a silly question, what is a 'suitable amp rating"?

I use schottky diodes 1000v 10Amp . You can buy them online 10 for a couple of pounds.

They will lower the voltage of a pack by about 0.25 to 0.5 v but if you use 5cell NiMh or two Life cells there isn't a problem.

Thread: DB Hurricane paint and finish.
08/12/2019 08:06:54

You can now get water based Evo Stick contact adhesive. Probably more expensive than copydex was but don't know if copydex is still available. There is also a similar product to copydex used by carpet fitters , might be worth investigating ?

Edited By Engine Doctor on 08/12/2019 08:07:35

07/12/2019 11:47:32

yes +1 The foaming glue works well on veneer and any that foams out can easily be sanded off when cured . Will need a plastic sheet with heavy weights spread over area to hold it down as its very powerful when it expands .

Jon Be careful with the CoG on the DB Hurricane . I built one some years ago and the CG was exactly as per the plan . First flight proved otherwise . Needed moving an inch further forward for pleasant flying. 

The full size was I believe the same . I have read  it somewhere in the past that the first Hurricanes that were delivered were just about flyable due to a rearward CoG and one officer refused to fly it in service until it was corrected . The article said they all had a large lead weigh attached to the firewall and an extra trim tab to counter this .

DB was was a stickler for copying the full size .Everyone I know who has had a DB said that they had to move the CoG forward from that on the plan . As you say wing loading isn't too much of a problem with such a large wing although the U/C mount can be loosened in a less than perfect landing if not built strong . The one I built had the built up wing and the U/C mounting  was incredibly strong after all the mounts were strengthened with tri-angular stock .

Good luck wit it and hope you get away with sticking the veneer down .

E.D.

Edited By Engine Doctor on 07/12/2019 12:01:37

Edited By Engine Doctor on 07/12/2019 12:02:49

Edited By Engine Doctor on 07/12/2019 12:06:28

Thread: Valve work
06/12/2019 14:54:28

Hello Winco . Sorry for late reply but trying to sort out the club subs renewals for 2020 with the added CAA and optional card business !!!

Cutting a slot is a good method especially if the bolt is knackered anyway and its accessible . For the head bolts use a good quality HSS Allen driver  link . They are sharp and grip far better than ordinary allen keys . Clean out the socket in the bolt head before inserting the allen driver so as to make sure the driver fits right into the socket . An old sharpened small allen key is ideal for this as they are pretty useless for undoing allen screws. Also a sharp tap on the end of the allen driver with a light hammer usually loosens them . Dont forget to undo and do up diagonally and dont over tighten them . Do replace any damaged/rounded bolt with a decent quality bolt when re-building.

Good luck and let us know how you get on

E.D.

Edited By Engine Doctor on 06/12/2019 15:05:34

Thread: Radio Queen ailerons
02/12/2019 17:23:18

Why ?

Thread: Valve work
02/12/2019 11:09:22

You could try squirting some Plus gas around the valve to get it moving .Cam followers are prone to getting stuck if the engine is poorly stored for a long time and will hold the valves open when the cam pushes them up and they stick. Agian a squirt of plus gas will usually free them with a little finger pressure . It would be wise though to strip off the head and remove valves to clean the stems and seats .Once the head is off remove valve collets in a big plastic bag . That way if you slip you will be able to find the collet.. To clean the valve stem and head I put it in an electric drill and use an old razor blade etc to remove any thick carbon then fine wet and dry paper to finish off . I use fine valve grinding paste thinned with either a drop of paraffin or thin oil to re-seat the valves. You can test the seat quickly by putting a few drops of thinners into the inlet and exhaust and check for leaks . As the valves or follower are are stuck I would also check the rest of the engine for any gumming or corrosion as this can Kill an otherwise good engine in seconds . A quick look in the cam box and in the back of the engine (take off the back-plate) and you will see if there is any corrosion to worry about . Its worth checking as the 80 is a powerful old lump and generally good runners ..

Edited By Engine Doctor on 02/12/2019 11:14:28

Thread: A new caption competition - winner declared!
02/12/2019 08:50:45

"You climb over and get it !" "NO you climb over"

Or

Someones fly tipped and old airframe over here !

Thread: Medway MFC indoor flying Sun 8th December . Gillingham Kent
01/12/2019 19:57:30

Medway MFC indoor flying this coming Sunday , December 8th 2019 at Medway Park Leisure Center Gillingham Kent ME7 1HF For more details go to ; http://www.doddington-kent.org.uk/MMFC/ This will be the third indoor session this autumn /winter Further sessions will be held on the second Sunday of each month through to march 2020 Sessions run from 10 am to 3 pm Costs £7.50 to fly for adults (children get a reduced rate). £1 spectators. BMFA membership/ insurance required to fly. Please bring BMFA cert. There will be a free bring and buy table , just put a donation in the Air Ambulance box if you sell anything, and a raffle . All profits go to our club charity the Air Ambulance Kent,Surrey and Sussex. please come along have a good fun day and help support a worthy charity . In the last year we have raised £1769 for the Air Ambulance so pleas come along and support a worthy cause .

Thread: The Gov't, CAA, BMFA & UAV legislation thread
30/11/2019 09:55:13

As per Ken Andersons thought Dept .Too many barrack room lawyers over analysing and confusing readers Lets have a simple how too from the likes of Andy Simmons and lock the thread

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