Mo'Best stuff

I am greatly enjoying the thread on the Mo'Best. I started building one a couple of weeks ago using the plans from PAMPA. I have the fuselage all but finished (254gm with no hardware and still needing final sanding), the stab made (28gm rounded) elevators at 4gm each with a little sanding still to do. do these weights sound plausable?

I am planning to fit a Brodak 40 is this enough engine? I sheeted the sides in opposite directions on each side and this has made the unit very torsionally rigid but it is still quite bendy along the length so I think that I will glass it to stiffen it up.

I was planning to do the wing as per the plan but the excellent pictures and description of the kit version makes me tempted to try it that way -Larry, have you thought of doing a wing only kit?

[photo not recovered: mo'best.jpg]

Regards

Mike

Nice work, Mike! I see you have built the original published version of the ship, which had diagonal balsa sheet planking on the aft. Several people reported problems with twists and distortions after clear dope was applied. Subsequently, I went to the 1/64" plywood fuse side planking, and it solves ALL problems!

However, your glassing solution is probably a good approach. On previous profile fuselages, I glassed them with .5 oz (using nitrate dope as the binder), very lightly sanded, and then covered with medium silkspan. I'm not sure this is absolutely as strong as it might be with a good epoxy binder, but it works pretty well, and there are no problems getting color dope to stick over it.

If you have a choice, start out with an OS .46 LA for this ship. Like the profile Cardinal, it has a large thick wing with lots of drag. The original design was for the OS .40 FP, but I also used an ST .51 on it with good results.

As for weights, 254g is around 9.5 ounces, which is I'm sure heavier than many profile fuselages. I have my previous prototype 1/64" plywood planked version here, and it is 214g (7.9 ounces). That fuselage is slightly taller and about 3/4" longer in the hinge line to hinge line measurement. It still has to be rounded, but it has no rudder glued on. There's also another difference, the fuselage balsa sheet is now 3/8" thick instead of 1/2" thick..

A valid complaint I get about the Mo'Best is that it is slightly too large for a .40 size profile ship. And profile fuselages tend to be heavier than well designed built-up fuselages, there is simply LESS material involved. And an extra light profile fuselage with a weak nose is almost a recipe for a crappy engine run, which makes the extra weight less an issue.

The Mo'Best wingspan is 58".. It's rather large for a profile.

Don't forget, I got into the "More is Better, so even More is Best" mode in this design, and perhaps it did end up slightly too big. My friend Robert Compton has built them in the 44-46 ounce range, and they fly well. And I've built pachyderms weighing another 10 ounces (they were PRETTY!) which also flew pretty well, again the wing volume makes it possible. But they are draggy, and good power is required.

Funny you should mention a wing only kit.. The full fuselage version of the Mo'Best is called the Mo'Beast and only differs in the fuselage.. John Brodak will be marketing the profile kit, after I build a couple of fresh Mo'Bests, I'll just want the kits minus the profile fuselage parts too! Maybe we can ask him.

Good luck with your ship!

[photo not recovered: 3e69bb3870f12ad5.jpg]

"I have no sceptre, but I have a pen." -Voltaire

Thanks for the info Larry. My plan for covering the fusalage is to use epoxy and fibreglass. I used to do this on the wings of my cross country slope soarers in the days when I could still run up hill. My method then was to first mix up a small amount of the laminating epoxy thin it and add a very light filler. I then apply a single coat as thin as possible on the area to be glassed pulling the epoxy out to the edges using an old credit card - the aim is to use as little epoxy as possible to seal the grain. When this is dry I give it a light sanding till smooth. The light glass cloth is cut to size and stuck down with the minimum of unthinned laminating epoxy - more scraping with the credit card to minimise the amount of epoxy used - I don't aim to fill the grain, just stick the glass down. once hard a very light sand to remove any specks then a coat of thinned laminating epoxy bulked out with the light filler to fill the grain - I still use the credit card to smooth the epoxy into the grain. more sanding and I expect to get a good paintable surface with the minimum added weight. One small cloud on the horizon is that I have only a small amount of the light filler and don't know if the company (Chemi-Tecnique) is still in existance.
I think that I will make sure that I can fit a bigger engine if necessary - I have an Enya 45 that should be fittable if I open up the bearers a bit before I finish the model.

Regards

Mike

As Larry said, my first MoBest weighed 43 oz. It was powered
by an OS FP 40. It pulled it just fine.
My second MoBest used the planked fuse aft as you did. This one
had a lot of play side to side and I had to put carbon fiber on the
outside of the fuse to make it stiff. It was fine afterwards and it too used an OF FP 40 and at 48oz,was ok.
On the third MoBest, the green one that Larry posted a picture of, it used the 1/64 ply sides and is very stiff.

LAST EDITED ON Oct-27-04 AT 08:49 AM (CDT)
 
Thanks Robert for that info, I guess I should skive off work early, go to the model shop and get some 1/64" ply. Suddenly I can feel a second Mo'Best coming on

Regards

Mike

http://www.mike-nelson.co.uk

Before you add the 1/64 ply, you might go ahead and do one fuse as you said you were going to do. Mine was just dope over silkspan on the fuse. You might add enough strength with your method.
Mine with the balsa planked aft fuse resisted twisting, but side to side
was worthless. With epoxy and glass, it might work out.

Yes my plan is to finish the current one with glass - I will record the weight gain accurately - then build a second one using the latest method

Regards

Mike