IOMICA Forum

Modelavionics seems to have been hi-jacked my Magiclamps

An aquaintance recently set up a wireless network for a pc and had been impressed with the range. It does not seem to be upset by other devices working at the same frequency and it does not seem to upset other equipment, either. I understand that similar technology is used in the Spectrum and Nomadi...

In reply to Arvin and Muzza I have recently been told that the scow shape originated from the days when the rating was based on waterline length. A boat with a long waterline would have a speed advantage over a short one. This resulted in long overhangs. By making the bow very flared, the effective ...

Thanks for the reply, Ralph.

From the web I see that the Futaba P-S5801 does not seem that heavy at 83g and I note that the turns can be adjusted up to six.

This could be just what I am looking for and with Xmas soon upon us ...

Cheers

Hi Ralph I've never made a model sailing boat before so I guess that I am coming up with some crackpot ideas. Author Spaldi01 was making some enquiries about sail winches, particularly of a Hitec type, and received some replies - Of theHitec HSR5995T, Lester Gilbet replied "Incredible specs! With a ...

Hi there! Since I have posted on this forum before and had helpful replies, please could I have some help with the following? Small batteries may not be ideal for supplying high currents, say, 6 amps to move the sail winch. Can a large capacitor (say 1 Farad) be connected across it to boost its powe...

Hi there, I have seen a wireless network card which says that it works on 2.4 gHz which is the frequency used by the Spektrum transmitter module. I think that this is also used by Bluetooth devices as well. It could be a little crowded on 2.4 gHz. Does this mean that we have to turn off our hands fr...

Hi RoyL I've done it now so if boat blows up I'll tell everyone here. I've ordered a lithium polymer battery charger chip from Radiospares and if the battery explodes then I'll have to go back to the drawing board! :( Here is a rough idea of the energy in watt hours stored per kg lead acid, 40 Lithi...

[quote]In fact the rules allow unlimited flare. What is limited is any "hollow" when measured parallel to the water line./[quote] Thanks for this information, Lester. I have re-read that part of the rules and it is now obvious to me. Perhaps the waterline shape of a Triple Crown with wide flared bow...

If I ran into something, the 2kg lead bulb would keep on moving and crack open the hull. If I had a section of thin walled aluminium tube connecting front bulkhead and keel it would prevent this. Similar bracing connecting standing rigging would let me run it nice and tight so that wind in sails wil...

Good point, Arvin.

Dual conversion receivers are also pretty impressive at rejecting noise but I would agree that outside, away from fluorescent tubes and other interference, anything goes.

Oh dear! I have just spent the pocket money on a lithium polymer battery 7.4V 800mahr. I took advice and the expert used these cells for electric flight. He had never had any problems with them and they have no memory effect and do not self-discharge. They are dead easy to charge - just keep the cur...

Thanks , Lester. This gives me some more ideas to ponder.

It seems that the consensus is that a slim hull works best. A slim hull would need less epoxy and my weight problem would be solved.

Are there any owners of beamy boats such as Boxkite who could claim that their design was superior?

I have just bought a pocket metal detector - the sort that you use to check that you are not going to cut through nails in a piece of wood or drill into gas pipes and so on. It cost me less than ten cans of drinks. I have also discovered that it will also detect carbonfiber reinforcement in epoxy re...

Awallin Many thanks for the link. It was most ..... interesting. However, the aircraft guys do give their equipment quite a hammering and use lots of cells in series with the associated problems with overheating of the innermost cells. We only need two cells to drive a sail winch so they will be les...

Many thanks for the replies, guys. I still don't know why a skiff type should be good in a blow. The bows are so fine that they don't look as if they would lift the boat out of the water if running downwind. I would think that it would have terrible lee helm if caught broadside in a gust and weather...

Hi, there everyone, I've just discovered how the price of Lithium Polymer batteries and chargers have dropped recently. As you probably know, they are used for electric flight since they are light and deliver a high current. I am concerned about using them since lithium is a very reactive metal whic...

Hi Ed. I understand from Fred who replied to another of my questions that expanded polystyrene is a foam material so I could not use it. I should have read the rules! When reinforced with aluminium tubing, foam would certainly take the load of the rigging. Anyone out there, - is it allowable to use ...

Thanks, Fred. I should have read the rules properly.

Can I build a hull out of expanded polystyrene and still comply with the class rules?
If the hull was strenghthend with a space frame of thin wall alluminium tubing is this still permitted?

Please help, many thanks

Hi Arvin Thanks for your reply. I was really thinking of expanded polystyrene. It weighs only about 6kg for 1 metre cubed so a solid hull would only weigh a few tens of grammes. If I cut a block to the shape of a hull and sheathed it in balsa/epoxy, it would be far stronger than a hollow hull. It wo...

Thanks Arvin
I am trying to make a winning IOM but I dont want to copy other peoples designs. However I do appreciate ideas from other people. I would also like to know why IOM's are designed as they are. All ideas are welcome.

In a reply to Nigel's "what servo do you use" , Peter said "you will still end up with a hull that is really too heavy in its ends" I am trying to design an IOM and I had read that they can be twitchy to sail. I thought that it would be a good idea to reduce this effect by putting the electrical bit...

Models are used to predict the performance of full sized hulls and therefore copying a full sized hull would logically work on an IOM. This is clearly not the case since large changes to a hull may not cause an obvious change in performance. Is it a case that sail design and sheet control systems de...

I am trying to design an IOM and have received lots of good advice from this discussion board, even when my questions showed my complete lack of understanding of boat design. Could someone help me with this question please? Airplane and full sized yacht fins usually sweep back so that eddies are enc...

I have yet to make an IOM so my question might seem a little trivial so please excuse this possible waste of forum space. I understand that sail dimensions are measured from deck level and the wind is usually strongest the higher you go. Why do most IOM's have the mast on the lower deck and not on a...

Epoxy HAS to be mixed in the correct ratio otherwise it won't harden ever, it is not known to give off fumes unless you get thermal runaway (so mix up small quantities at a time or spread it out in a roler tray) and therefore is safe to use inside. Most forms of epoxy will deactivate if you mix some...

I have an interest in a schools IOM project and seek guidance as to environmental considerations. Sand gives a rough finish to a lead casting and I do not relish the idea of sanding a rough lead bulb because of health and environmental issues. Can a resin mold be used to cast the bulb or is there a ...

RRS 53 could be accidentally contravened by buffing up the hull if a waxy mold release agent had been left behind on the resin surface of a grp hull or if the hull was sanded down lenghtways. It can be deliberately contravened by dusting an invisible layer of hydrophylic compound over the hull. If R...