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Member postings for Chris Walby

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

Thread: Has Your Club Made Any Decisions Regarding The Coronavirus?
02/04/2020 14:19:16

One thing I have noticed while walking the dog at 9pm is how quite it is with no aircraft/car traffic noise. We are in an urban area with the fields a short distance away.

The other thing is how fast the wildlife has adapted in a short space of time, normally the odd hoot of an owl, but in the past six days

Different days and locations with two foxes crossing the normally light trafficked road, hedgehog just off the path next to the road, buzzed by an owl as if I was intruding on their patch and plenty of rabbits that were taking advantage the conditions.

Thread: Scratch Build Twin
02/04/2020 10:30:23

Jim, messaged you a couple of days ago, hope you are well. Chris

Thread: Focke Wolf Ta 154 Laser
01/04/2020 20:57:55

Moving on the next decision was regarding U/C as the original had fixed, but I though it deserved retracting.

Chat with Dave at Inwoods resulted in a very nice nose wheel oleo and retract, a couple of retracts and some buggy shocks. Mock up resulted in this

 

20190329_185643.jpguc mock up v1.jpg

Now at this point I realised I could make the retracts, but might never get the rest of this project progressed so I started a conversation with Ken King.

I sent some drawings and the mock up and Ken did lots of thinking with the focus on lightweight and simple design.

Really please with the result and can take no credit for Ken's great work. If it flies okay I will add tubes over the rods to make it look a bit more scale.

20191024_105827.jpg

Around this point we spotted the UC is in front of the C of G

Edited By Chris Walby on 01/04/2020 20:59:21

Thread: DH89a Dragon Rapide
01/04/2020 20:41:22

David, If you are struggling with the split wing you could always have a chat with Chris at SLEC. He designed in wing tubes on a one piece wing (now three piece with tips and centre section with nacelles). Best bit was everything lined up although the ribs are not equally spaced and the tips have dihedral compared with the centre section.

Good luck whatever you decide smiley

Thread: Focke Wolf Ta 154 Laser
01/04/2020 15:46:45

Martin - Did Jon not give you a set...strange surprise, mind you he did he didn't give me a set with the last engine either crying

Jon might know what there true purpose is, but being a new boy I just thought they were spacers so the socket to nut does not foul the side of the engine bearer + they look nice.

PS - I think washers fowl as their OD is greater than the nut across corners diameter.

Thread: Flat Car Battery from non-use of car
01/04/2020 14:51:21

I would be inclined to take the car out for some exercise once a week for 30 minutes at a moderate speed

Rational

If it fails to start when exercising it you can fix it

If you need it in an emergency you know it will start

If you get stopped by Plod just say you are over 70 and the car may be needed in an emergency + you are going out for essential supplies - petrol

All other options involve tinkering which is okay if you have the time, skill and equipment to do so.

Thread: Focke Wolf Ta 154 Laser
01/04/2020 14:40:45

Cliff, I built a TN Moskito but In kept breaking motor bulkheads and cowls every time I landed and in the end resorted to folding props and reduced performance as you don't have the same choice as standard props.

I tried differential throttle control as mine did not have a rudder servo - very weird yaw and un-scale like + I found that colour scheme almost impossible to see with a winter sky against trees (funny that!). After about 4 major rebuilds due to crash damage it ended its live with a 50ft lawn dart (not fully explained but either RX or ESC failure - money is the ESC and at low speed, low altitude and no rudder not catchable).

Martin - I am at a total loss as to your comment as the photo clearly shows the manufacturers supplied engine bolts with rare spacers + recommended Nylon engine mount and ply bulkhead. This was the prototype bulkhead and the final supplied by SLEC has the beech bearers (photos will be published in due course) oh and the engine rotated 90 degrees for carb/tank level.

I'll post progress shortly and thanks to all that are following.

31/03/2020 21:07:26

I'll be compressing the last 12 months into hopefully what would appear to the reader quite a quick build although rest assured its been very time consuming and its not finished yet!

Lets start with the airframe, apologies to the trad builders, but I don't think I am going to live long enough to cut wing ribs and bulkhead by hand so it was off to see Chris at SLEC

No problem with increasing the wingspan from 70 to 80 inch, help in selecting wood sizes and a set of nacelle parts to assist with engine and U/C design.

20190517_133949.jpg

Now the first issue was that the Laser 70 engine sits on engine mounts and the bulkheads are in the wrong place. Good news the was to use the beech bearers for the U/C, but getting the U/C to retract into the nacelle was going to be a challenge.

20190526_205847.jpgPS Not engine or tank final position!

Edited By Chris Walby on 31/03/2020 21:10:10

31/03/2020 20:52:29

A bit of history

Apparently the Germans were very impressed with the DH Mosquito in its role as pathfinder and photo reconnaissance and especially with its use of non metal airframe. Kurt Tank of Focke Wolf had already been designing aircraft using wood composites and here was an opportunity to submit a design for a twin engine night fighter with a similar performance as the Mosquito.

Despite having the same wingspan and composite wood air frane the Ta154 differed in being high wing and fuel tanks within the fuselage. This allowed for a thinner wing section and less likely to be damaged under fire.

Major problems arose when their only Tego film (glue) factory was bombed and an alterative less strong glue was used. Worse than that they later found after a number of wing failures that the glue was corrosive to the airframe.

Back to my Ta 154

Plans for 70 inch version were obtained (if only I had looked in Outerzone!) but not to worry at least I has a hard copy to look and measure over.

Looking at the wing area and target weight it soon became apparent that a 70 inch version with twin Laser 70 in it was going to have a high wing loading.

The answer was to copy the Mosquito and go for 80 inch wingspan which brought me to the U/C. The original plan had fixed and while in the 70's/80's there was no real economic alternative I thought it could not be too difficult to do.

31/03/2020 19:50:01

ta 154.jpgIn Feb2019 having flown my Laser powered Seagull Mosquito I hatched a plan to obtain the other Moskito.

This one was not going to be quite as easy as buying and modifying an ARTF, but how hard could it be?

Thread: Does the size of spinner effect prop performance ?
31/03/2020 17:57:49

IMHO In theory yes, in practice no

Why, the air is very turbulent near the spinner and cowl + the props angular velocity is low compared to the tip.

Others more expert than me will correct me, but I think its the outer 2/3 of the prop that does the work so the size of the spinner (within reason of course) will no make that much difference.

Hope that helps

Thread: DH89a Dragon Rapide
31/03/2020 17:52:09

Watching with interest and I once spoke to a chap that makes foam veneer wings about a replacement for my mossie. His response was which wing profile (for mossies) out of a choice of 5 did I want as each designer picked a profile to suit their design. My point is that its designers that select profiles to suit their designs for their reasons and unless to can discuss with the designer why they made that choice its best sticking with the original design.

All the best

PS Don't ask my why sad but if you consider two or more piece wings make sure the wing tubes are set up in the design stage (far easier) for the ribs and then there is no chance or getting them slightly non parallel at a later stage.

Thread: Will we continue to get the magazine (RCM&E)?
31/03/2020 17:38:04

How about some nice simple explanations around say:

  • Why IC engines need to have double nuts on the prop shaft when other engines use a single bolt?
  • Why some ESC manufacturers say you don't need capacitors when extending ESC to battery leads and some do?
  • Do we really need to pin hinges and how do you pin a small Robart hinge?
  • How do you fly a low inverted pass without lawn darting at the end?
  • Which is the best TX/RX combo?
  • Why do some flyers land down wind as if its the only option open to them?

Anyone think of any others wink

Thread: Scratch Build Twin
31/03/2020 17:05:34

David,

Where does it show the BEC's in parallel?

shadow model wiring.jpg

The upper BEC powers the U/C only, notice the red wire cut to the RX.

This is standard practice when using U/C as if it jams then the BEC will burn the U/C motor out or its inbuilt safety will function but it will not brown the RX out.

I don't think its ever good practice to parallel BEC's, if the ESC BEC is not large enough then put a separate UBEC/BEC in that can handle the expected load. I had an interesting chat with George at 4Max regarding my Laser 180 YAK and his advice was keep it simple and have one 20A UBEC (It does not have U/C) but in the event of a servo failure the UBEC voltage will not drop below the RX min voltage as it clears the fault.

 

 

Edited By Chris Walby on 31/03/2020 17:07:42

Edited By Chris Walby on 31/03/2020 17:08:16

Edited By Chris Walby on 31/03/2020 17:13:24

31/03/2020 14:48:20

Hi,

Nice long nacelles so should not have too much of an issue getting the C of G although I would construct the nacelles/fuselage with the option of moving the batteries around when the time comes to check + they are close to the fuselage which has its benefits.

A couple of electric and IC Mosquitos have everything as far forward and some lead to achieve C of G where as my Dual Ace needed nothing. I have another twin tricycled which was sitting with 700g nose wheel weight and I am currently engineering as much back to the tail as possible. My point is that the model may not reflect the full size with respect to weight distribution.

Regarding your RDS, are you providing access panels to adjust the aileron RDS grub screws, only asking as sometimes its easier (if you have the option) of putting the ailerons on different channels and thus you can adjust their centre points separately?

Are the flaps fuselage to nacelle or extend to the outer side of the nacelle - just interested wink

Thread: NEW POLL - Has home isolation prompted you to start trad' building?
30/03/2020 13:46:57

Still building my Focke twin and amazed at how much time it takes to do quite simple parts.

Still have to finish:

  • TN DC3 - electric
  • Repair of an electric twin Mr Dumb thumbs broke
  • Repair TN twin that suffered an electrical failure
  • Repair a FF ME109 that suffered an electrical failure and lawn darted

Start:

  • Slim Twin
  • GTC build with another club mate
  • Tiger Moth
  • Hurricane

Rob....a DH Hornet you say.....do spill the beans....I have looked but not found much recent in the way of plans

Thread: Scratch Build Twin
30/03/2020 13:35:33

G-JIMG, just because people are not replying is no indication that people are not interested.

As a youngster I was told if you have nothing to add then don't open your mouth (or type) and I think there is nothing worse that people chipping in off topic for pages and pages that other at a later date have to plough through.

Watching with interest

PS Mod feel free to delete this as IMHO its off topic

Thread: Vibration absorbing engine mounting
30/03/2020 06:52:50

IMO rubber bobbins would need great care and additional frequent checking as from experience as years ago their performance was poor. We used them for exhaust and silencer mounts on 2 stroke motorcycles. The mounts did not like the oily conditions and in the end the ACU invoked a rule where a wire strap was required so that when silencers fell off they did not become projectiles.

The thought of any IC engine at WOT moving around or breaking loose is very concerning + if the mounts are behind a cowl how do you visually inspect before each flight where as holding the prop prior to starting instantly confirms all is bolted tight.

The alternatives made for the specific purpose of engine mounting look okay and as said above I would seek the advice of the manufacturer as to their recommendation.

Off topic, but my observations is that significant noise comes from the stalled prop at WOT and the drumming effect of the airframe when noise testing.

Thread: Quick depron build plan needed for home flyer.
26/03/2020 12:22:11

Nutball….Quick and easy to build, plus easy to fly....fun. Whats not to like it

Search Nutball on the forum thread and you will find info

or here

https://www.modelflying.co.uk/forums/postings.asp?th=140020&p=4

 

Edited By Chris Walby on 26/03/2020 12:25:15

Thread: Peter Miller asks what next?
25/03/2020 07:48:03

Peter,

Interesting choice of the Pilatus P-2 and looking forward to following the design and build log (assuming you will do one).

Did a quick search of the web for details and I think it will be a nice model to fly with a wide flight envelope and your designers touch wink

What size (wingspan) and motive power plant are you considering for this one?

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Has home isolation prompted you to start trad' building?
Q: The effects of Coronavirus

 Yes - for the first time
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 No - Ive existing projects on the bench
 No - Im strictly an ARTF person

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