John Cobb’s Crusader

[Paul TParticipant @pault84577]

Has anyone got any plans or details of John Cobb's Crusader that I can copy or buy.

Paul

Edited By The Fat Controller on 09/06/2012 18:40:10

[Paul TParticipant @pault84577]

[ashley needhamParticipant @ashleyneedham69188]

Paul. Never heard of it..but what a looker.

Did it actually do very well or wot?? have no time to google just now, tea time beckons

Ashley

[Paul TParticipant @pault84577]

Hi Ashley

Yes it worked…it did 200mph on Loch Ness but crashed and killed John Cobb.

I have a request to produce a 1:8 scale set of cad drawings so I am busy gathering information.

Paul

[Yabbie1Participant @yabbie1]

Paul,

Have you by any chance heard of a publication known as Model Boats? Sorry, I couldn't resist that!

The May 1956 issue of Model Maker/Model Boats carried an article by Robert Campbell on building a Jetex-powered model of the Crusader. The accompanying plan (MM426) is fairly basic but worth a look on the principle that any information can help to build a complete picture. I could scan the article for you (with your permission!) if you don't have this issue.

With regards, Yabbie1.

[Paul TParticipant @pault84577]

Hello Yabbie

Model Boats?……..I have heard of it before isn't it edited by that chap who made the HDML Paul Flashman or something like that (or was that Tom Brown)

That would be wonderful and thanks for the offer please let me know when you are ready and I will pm my email address to you.

Thanks again

Paul

Just had a thought about copyright I will check with Paul that this is ok before we go any further.

Edited By The Fat Controller on 23/06/2012 14:16:01

[Paul TParticipant @pault84577]

Hello Yabbie1

I have asked Paul and he informs me that there is no copyright issues so I would be obliged if you would scan the documents for me.

Thanks again

Paul

[Yabbie1Participant @yabbie1]

Well, as long as the editor said it's okay. Scans of the article have been sent to your personal email address.

Yabbie1

[Paul TParticipant @pault84577]

Hello Yabbie1

Email address sent by PM.

Thanks

Paul

"The Editor" sounds like an Arnie action film, I wonder if Paul says 'I'll be back' every time he leaves his office.

[Colin BishopModerator @colinbishop34627]

He doesn't have an office Paul, he works from home….

Colin

[Paul TParticipant @pault84577]

I thought that all these media moguls worked in huge glass buildings and had offices the size of aircraft carriers.

[ashley needhamParticipant @ashleyneedham69188]

I heard "the editor" worked from a special cabin on the QM2..just a rumour.

A jetex powered model !! and for its first trip, if you didnt get it QUITE right…….

A modern version may well get away with a ducted fan, but you would have to enlarge the air intakes for a larger mass flow of air, or have a mesh fuselage portion to accomplish same? Hmmmm sounds like a project to me,

Ashley

[Paul TParticipant @pault84577]

Hello Ashley

I am drawing it to take one of these jet turbines that the model aircraft chaps play with.

Its a Graupner G Booster 160 which produces 160N of thrust (36lbs in old money) so the hull has to be very strong and produce some downforce as there is a real chance of the thing becoming airborne.

I am glad that I wont be using it.

Paul

[Paul TParticipant @pault84577]

Ashley.

Here is a picture of the turbine in question……they have come along way since those early jetex motors.

Edited By The Fat Controller on 26/06/2012 07:00:26

[ashley needhamParticipant @ashleyneedham69188]

Paul. Now theres a thing..i/c engines may be banned on ouir pond, but it doesnt say anything about JET engines….

Not cheap, are they..

Ashley

[Paul TParticipant @pault84577]

Its still IC

[Peter FitnessParticipant @peterfitness34857]

You'd need a pretty big pond for a model powered by that!

Peter.

[Yabbie1Participant @yabbie1]

Paul,

I have come across a much more recent article on the Crusader by Peter Hill, in the 30April-27May 1999 issue of Model Boats. It includes a contemporary (1952) account of the design and testing of its stability via a 1:16 scale model that originally appeared in Motor Boat and Yachting. There also seems to be mention of a 1:6 model with a 30lb thrust rocket motor- similar to the turbine you mention. It's quite detailed and interesting. Have you come across this article?

Yabbie1

[Paul TParticipant @pault84577]

Hello Yabbie

No I don't remember it but I will have a look through my back copies.

Thanks for the update.

Paul

[Paul TParticipant @pault84577]

Hello Yabbie

The drawings are finished and have been sent on there way, thank you for all of your help.

The builder intends to make two versions, the first which will be made from plywood and used as a test bed to set up the engine and controls and the second will be made from carbon fibre and used to make the speed runs.

The only change to the original design is the addition of a motorised hydrofoil which will help adjust the trim when the boat is at high speed.

Thanks again for your help and support

Paul

[carl brothertonParticipant @carlbrotherton75833]

I am trying to build a model of Crusader at present, as an electric RC straight running boat

My problem is that I have purchased a few electric drive line parts from HK. Being an aeromodeller rather than a boater, I do not know how flexible drives are assembled.

I have also deliberated a bit about the CG. I have concluded it should be over the rear sponsons., but do not really know.

[Paul TParticipant @pault84577]

Carl

To enable a better understanding of your CG problem can you tell us what motor and battery combination (including size and weight) that you intend to use and the overall dimensions of your model.

Paul

[carl brothertonParticipant @carlbrotherton75833]

Paul T

I have only just realised that I have had a reply. I must not have ticked the box.

My boat is 600mm long.

[Paul TParticipant @pault84577]

Hello Carl

Given the available information the natural centre of gravity is at a point 15 > 25mm below the point shown.

Without knowing the size and weight of the equipment being fitted I can't be more specific but I can confirm that The Crusader is very 'twitchy' when running at speed and it is important to keep the weight low in the hull.

I would suggest putting the batteries in the sponsons to widen the weight footprint.

I hope this helps

Paul

Edited By Paul T on 21/01/2013 06:56:39

[Ben Smith 2Participant @bensmith2]

Hi I just came across this looking for a copy of the plan for the crusader, my dad is looking to build one with edf and i cant get a copy anywhere, Does anyone know if there is a pay to download copy anywhere, I have searched all over with no luck, Thanks Ben.

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