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Member postings for Alan Gorham_

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

Thread: TN Hunter EDF
23/01/2020 12:07:17

I think it's very likely to have been this website:

www.solarfilm.co.uk

Thread: elecrtic retracts
22/01/2020 09:26:00

80 and 85 degree electric retract units are available.

Thread: CAA registration take-up?
17/01/2020 18:21:32

I wish I understood 10% of what you wrote there Don.

17/01/2020 17:58:21

Lovely sentiments Steve, but it's easier than that:

-Tick box on BMFA portal when rejoining to advise them to register you,

-Don't take test as already hold a BMFA cert which is recognised by the CAA as proof of competence.

-Wait until CAA email with the operators number.

-Carry the pre-printed exemption notices that the BMFA kindly supplied in the last BMFA news.

So it seems you have over-complicated things as well as been insulting!

Thread: Vintage Futaba servo FD17M - safe voltage?
17/01/2020 14:29:56

Back in the day when that servo was current, 4.8V NiCd packs or 6V dry battery packs were common. I'd say you would be pushing your luck trying to use 7.4V. If you want to use the LiPo, why not fit a uBec to regulate the LiPo voltage down to 5V?

Thread: Ares Indoor Sopwith Pup
12/01/2020 17:38:40

This is an old model. It's been out of production for a few years at least which is why you can't find any suppliers with stock.

There's a used one for sale on the BMFA classifieds:

**LINK**

Thread: Paint masks& markings
12/01/2020 13:21:11

Flight line graphics were on a hiatus while they either moved or built a new workshop.or something. Best check if they are back.

Thread: If I fit floats to my Senior Telemaster will I need a more powerful engine?
11/01/2020 14:03:28

I think you are in the best position to answer that question David. I can see you have had many Telemasters including a 40 sized version. Where did you set the ch on that model? If not as per plan, why not? How did it fly? The only reason to set the cg forwards on a float plane conversion of a land plane is to help avoid any tendencies to spin as a result of a loss of directional stability due to the floats side area opposing the stabilisation of the fin. Its often not necessary. My Flair Cub and Limbo Dancer both fly with their cg in a fixed location regardless of wearing floats or wheels.

I did improve my LoBoy by bringing the cg forwards about half an inch with floats on. It made the model much more stable when flaring onto the water so it's not an exact science.

10/01/2020 15:27:56

My experience of over 20 years of float flying is different Piers. I don't protect my receivers at all - it can actually cause more problems with condensation build up in the receiver if you continually move the model from warm to cold places. If you are getting water in the fuselage of a conventional style model on floats then something is wrong, most usually spray thrown up from poorly set up floats.

I certainly don't epoxy glass the fuselage just for the sake of it, most of my models are film covered with perhaps some solarfilm clearcoat painted in the radio bay as well as the tank bay.

I do agree with your advice about the sealing of covering film edges however.

My "Shark" flying boat had a balsa and Liteply fuselage/hull covered in Oracover. It was a relatively small 50" span model which consequently placed the wing/fuse join very near the waterline.

It was most certainly not epoxied and it never got water inside, despite many, many flights in some very rough water conditions.

pict2730.jpg

10/01/2020 13:12:02

Decent point Robin.

I use Titebond 3 woodglue in models that will see use on water, but if you ensure the wing seat is well sealed with a bead of silicon sealant and the firewall is sealed up likewise where the fuel tubes/throttle linkage pass through it you will be unlucky to get water inside the fuselage.

On a high wing model it is likely to float upside down with the wing partially submerged. Any exit holes for aileron/flap linkages will let water in so a good waterproof glue is helpful.

Of course, getting a decent float setup in the first place will help to minimise the chances of the model turning over in the first place!

10/01/2020 12:37:26

David I agree you are looking good on float nose length ahead of the prop, so that's a start.

Other people have advised you to shuffle the CG slightly forward from the sweetspot for the landplane version, so bear this in mind when setting step position vs CG.

I've already looked at the pics of your proposed models for conversions David and they all looked OK to me regards rudder size. It wasn't me who recommended increasing the size of anything. Hopefully you can see that my philosophy is to use my landplane models on floats with as few changes as possible. Because you are building from scratch in this case it certainly won't hurt to have a bigger rudder.

10/01/2020 11:48:18

A model with a reasonably sized air rudder does not need any enlargement to help steer on the water.

For example, the WOT4 works perfectly well. Many, many conversions have been done.

David Boddington was guilty perhaps of undersizing his rudders on many of his sports model designs. I flew a Barnstormer 63 for many years and it would definitely have benefitted from a bigger rudder.

None of my wheeled model conversions have needed a bigger rudder to steer on the water without water rudders. nor have they needed extra sub-fins for airbourne directional stability.

10/01/2020 09:45:00

David, based on the information you've given about the floats in your previous post this morning, I would urge you to check one more dimension against your proposed fuselage....

If you lay the fuselage plan out and lay the float plan out in the "installed" position ie with the step in relation to the CG as per the manufacturers instructions, do the noses of the floats stick out ahead of the prop by at least half the proposed prop diameter?

If they do not you will find the model hard to get up on the plane and in the worst case, opening the throttle will make the floats want to dig into the water, pulling the models nose down. Now is the time to resolve that question!

10/01/2020 09:32:34

Personally, the vast majority of my waterplanes are powered by a nice oily engine as you can get an engine wet from spray blown up from the prop or turning the model turtle and put the engine back into service very quickly the same day by just emptying out any water from the glowplug hole, rinsing out with fresh fuel, before putting the plug back and starting the engine, getting it right up to operating temperature and that it.

So long as your engines are reliable (ie will keep running so long as there's fuel in the tank) and will idle for long periods and pick up instantly everytime, there is no problem.

Electric power is obviously immune to any running issues, but is more susceptible to a good wetting. The motor and ESC especially. They can usually be rescued but they must be dried out very thoroughly.

09/01/2020 14:37:40

Sorry...one more conversion I just remembered:

13584925_10209908706664645_9021146274966196044_o.jpg

09/01/2020 14:36:13

David in general it is much easier to select a model you wish to put floats on and then design and make a set of floats to suit.

You will get much better results doing it that way because you have total control of the float length, step position relative to the aircraft cg and total float volume.

If you compromise on any of those factors you will get poor water handling and poor take-off performance. An model with an ideal setup should be able to come up on the step and then take off just by opening the throttle in my experience.

A sub-optimal setup may need the presence of a chop on the water to help get up on step, or some hefty elevator work that may lead to the model taking off in a stalled attitude etc.

Also, if you get the relative length of the floats correct you will find you can manouevre the model on the water without water rudders. I don't use them generally.

As well as float length v fuselage length, you need a set of floats that are proportioned so that the float noses come out to around half a prop diameter in front of the prop arc and with the step positioned around 1/2 to 3/4" behind the CG.

It is worth persevering to get all the parameters right because it is fantastic fun flying from water. here are some of my own models with own design and made floats:

flair cub float.jpg

img_2126 (600 x 417).jpg

img_4421_1.jpg

macchy.jpg

Thread: ESC overheating.
08/01/2020 12:55:54
Posted by Nigel R on 08/01/2020 12:49:52:

Theoretically, you could have linear control of a brushless ESC. It would add pointless complexity to the circuit though, probably another stage of FET, and require massive heatsinking, probably to the point of rendering the thing utterly nonviable.

The ability to PWM control power comes only at the cost of additional software complexity in the ESC's CPU, where control of the brushless commutation is already being done.

That is not strictly true for every ESC as there are dedicated BLDC commutation IC's available that allow workload to be taken away from the Microcontroller.

08/01/2020 12:40:22

Linear and switch mode just refers to the design of the BEC circuit fitted to the ESC and is nothing to do with the motor control FETs.

Thread: Blue modeling foam source
08/01/2020 09:52:06

Blue foam used to be called Dow Floormate 300, but Dow sold their insulation business and the blue foam has been off the market for over a year. It now seems to be back in manufacture by the new company Ravago.

Insulation Express are the retail arm of Sheffield Insulations group and they are selling single packs containing 8 sheets of foam 2500 x 600.

Blue Foam

The other alternative for smaller quantities is offcuts used by manufacturers but that takes some detective work.

Thread: CAA Registration Impact on STEM Activities
07/01/2020 17:42:20

Yes in formal document or publication I understand the convention. This is a hobbyists forum for a technical hobby. Do we really HAVE to formally introduce acronyms (of which our hobby is full)?

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