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Member postings for Martin Harris

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

Thread: Thinking aloud about Spits...
12/09/2019 16:43:31
Posted by Dad_flyer on 07/09/2019 23:26:10:

There was a red one that used to do shows apparently. It was the wings of one spit, and fuse of another. "Red spitfire" search will get you pictures.

Search for G-FIRE and/or the owner, Spencer Flack. You may wish to avoid reproducing the strobe lights in the gun ports given your aversion to its military heritage!

12/09/2019 11:47:25

Good point Pete, the up aileron trick has tamed many a tip staller although I'm not sure about that version with the non scale ailerons...

Edited By Martin Harris on 12/09/2019 11:49:26

12/09/2019 11:23:30
Posted by Foxfan on 12/09/2019 08:15:24:

Was that too slow? Looked pretty fast to me. Maybe he just pulled the wrong stick.

The whole flight was way too fast for my tastes. I've so far not seen anything that quick at our club!

 

Martin

I'm talking about the crash within the first 30 seconds of the video. The model appears to dead stick and while being manouevred, drops a wing and spins. Many models would probably have survived without incident but the more heavily wing loaded and less forgiving wing profile of the Spitfire meant that it was prone to flicking when pulled into the turn. Speed is a simplistic explanation, what actually happened was that the wing exceeded the critical angle of attack. In a 60 degree bank, for example, stalling speed doubles.

The hard turn after the engine cut bled off much of the energy from the model's speed and by the last turn with almost certainly some elevator being applied to hold the nose up (hoping this observation doesn't offend Steve but we've all done it) put the model in a position vulnerable to stalling at that point. You just can't get away with stretching the glide with such a model.

I used to set up my 1/12th scale combat models so that at full throttle, the model just wouldn't flick out of a maximum rate turn - but you had to be careful if you were trailing an opponents streamer as full throttle stalls could then still occur!

Edited By Martin Harris on 12/09/2019 11:45:58

Thread: Ashbourne 2019
12/09/2019 10:54:12

Sadly, I am otherwise engaged this weekend.

12/09/2019 00:48:20

What on earth is oatcake? Sounds like something you'd feed horses!

Thread: Thinking aloud about Spits...
11/09/2019 23:32:33

See Stephen Jones' second video...the consequences of getting too slow while manouevring are demonstrated very well!

Edited By Martin Harris on 11/09/2019 23:34:35

Thread: Alternative servo linkage
11/09/2019 23:03:35

I came up with this solution as a retro fit when it became apparent that my Tony Nijhuis Hawk would need tail weight. It drives the rudder (normally fixed) from below. It's worked well with little or no slop but I don't know that I would recommend it as an aileron or elevator system without a bit more engineering. It might give food for thought?

02280003.jpg

Thread: Latest CAA Update
11/09/2019 22:00:43

Aren't we a helpful bunch!

11/09/2019 21:58:54

Link for convenience...

Well done to those at the BMFA for their hard work. Let's hope that this is the beginning of a decent solution.

Thread: All weather flyer.
11/09/2019 18:07:42

I've spent many an hour flying an EPP profile Extra in silly winds - very responsive controls and no undercarriage to damage... However, my current weapon of choice for the more challenging conditions (no doubt it'll be out tomorrow) is a small (43 inch) Seagull EP Extra 300 which seems to handle almost anything I throw it at - I can't match Brian's Great Storm exploits but I was flying earlier this year in measured 31mph gusting 50 winds, necessitating a genuine full throttle approach!

The common factor isn't a high wing loading but control responsiveness coupled with predictable handling. I will sometimes put the battery further forward in very rough conditions.

I will admit that I fitted a Jeti Assist (stabilised) receiver to it recently as an experiment. I have to say that it makes rough conditions flying almost as easy as a gentle summer evening's flight. I often have to be advised that conditions are turbulent when I have it activated! I could certainly recommend a similar set up to anyone nervous of flying in strong winds.

Edited By Martin Harris on 11/09/2019 18:12:29

Thread: Military J3 Cubs
11/09/2019 17:36:47

I may be wrong but weren't the J3 Cubs used in the Civilian Pilot Training Program which was designed to feed budding pilots into the military?

Photos (B&W) I've seen have all suggested them to be in the standard Cub Yellow scheme - probably thought to be a very suitable colour in a busy training environment!

I don't recall seeing any references to J3 Cubs in military service but there may well have been some examples...

Edited By Martin Harris on 11/09/2019 17:38:00

Thread: IC or Electric for Ripmax DeHavilland Tiger Moth
10/09/2019 16:57:38

My gut feeling is that a 40 might suit the model better than a 30? So much better than adding lead if it needs some nose weight!

10/09/2019 13:53:03

At one time, the importer for Airsail kits was able to supply a pipe for their Chipmunk which would achieve Cymaz's suggestion - the engine and cowling arrangement is very similar of course. IIRC Kevin B. on this forum was involved with someone restarting production of Airsail kits so he might possibly be able to assist?

Thread: Finished
10/09/2019 09:48:17

I'd go with the first option - there are many obvious differences Dave.

Thread: New Poll - sticky situations.....
09/09/2019 22:50:17

Too late now but warm soapy water will soften the bond within a few minutes. A bit awkward keeping it away from the bottle in this case but it's a bit less dramatic than hacking your fingers apart with a scalpel...

Thread: IC or Electric for Ripmax DeHavilland Tiger Moth
09/09/2019 14:31:58

I've yet to see an electric powered full sized Tiggie. It's your choice but mine would be a nice 4 stroke glow mounted inverted. (I know the full size doesn't use glow fuel but the question doesn't specify fuel type!)

Thread: Thinking aloud about Spits...
08/09/2019 00:30:00
Posted by Foxfan on 07/09/2019 22:48:16:

So where does this almost universal belief that a model Spitfire will always re-kit itself in double quick time come from?

I'm delighted you gents all seem to think otherwise.

Martin

Please note what has been said - the Spitfire is generally well behaved in normal flight but the re-knitting almost invariably occurs during the landing approach or occasionally on a hurried take-off. I have lost count of the number of model Spitfires that I've seen dropping a wing and cartwheeling to destruction after flying the sort of approach encouraged by learning on low wing loaded trainers and low wing follow-ons.

This is where the model Spitfire gains its (well deserved) reputation - and unless you have mastered consistent power on approaches, yours is very likely to add to the statistics unless it's a sport scale design. 

P.S. However you paint a Spitfire, and beautiful aircraft that it is, there's no denying that it was built as a weapon of war.  I'm sure that rather than glorifying war, most now see it as a celebration of the engineering design that led to such an iconic machine being created. 

Edited By Martin Harris on 08/09/2019 00:38:09

Thread: OS 40 four stroke, inverted?...
07/09/2019 12:12:07

Many of my models spend the majority of flight time in anything other than level flight.

Thread: Commons Science and Technology Committee Enquiry on Drones
07/09/2019 12:07:36

You'll need to tell me. I'm trying to see the picture on an iPad mini in bright sunshine without reading glasses...

Thread: Best/Safe practice or wiring electricmotor - ESC- On off switch - Reciever
06/09/2019 09:56:40

I can't disagree with your philosophy - mine is very similar except I see the extra layer of security being useful as long as it isn't relied on. I'm always at pains to point out to clubmates that any safety device can fail for physical or human error reasons and to treat any electric model with the flight battery connected in exactly the same way that they would with an idling IC engine.

How many times have throttles been knocked open with transmitter straps, for instance? I've seen this with both electric and IC and a throttle lock prevents this happening.

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