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        Discussion Martin 167 Maryland design and build.

#1 RyanPSU21 Jun 15, 2008 08:27 PM

Martin 167 Maryland design and build.
 
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Edit 9/6/08 I'm just editing the thread title to include the build off designation since this will be my entry.

It's time to start the next project or start thinking about it anywhere. I'm going to make my second swing at designing a plane on this and started on the plans tonight.

I'm going to make a Martin167 Maryland which was a US pre-WWII bomber. It is going to be 1/9th scale which gives it a wingspan of about 81.3 inches. Power is going to be something cheap such as 2 speed600's or cheap brushless. Around 600 watts should be good for scale like performance. Construction is going to be as much stick as I can with minimal sheeting to come out as light as possible. It will have retracts and probably flaps too. Wing area will be around 980in^2. I'm thinking of a final weight around 7 to 8 lbs. That will give a wingloading somewhere between 16-18 oz/ft^2

#2 Scaledown Jun 15, 2008 11:46 PM

The Maryland is of interest to me because my great uncle went missing over the mediterranean while piloting one.

I see you found a good three view. I couldn't find one. Nice plane to model, flat sides and mostly simple curves. You could paint it in RAF or maybe French colours.

Best of luck.

#3 RyanPSU21 Jun 16, 2008 07:21 PM

I found in in some link someone posted a few days ago in general chat. It's not a great 3view. I've already found some dimension discrepencies between views. It will do though.

I chose this because it appears like it will be a fairly easy structure to recreate. It's proportioned nicely like a fairly generic plane with more generous wing area then WWII designs. I can't recall ever seeing a model of it done yet though as soon as I say that 10 people will probably jump in saying they've already done it. Most were built and sent to the RAF or French so undoubtly in the end it will get one of those 2.

#4 RyanPSU21 Jun 16, 2008 09:10 PM

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Some more CAD work done tonight. I spent most of the time trying to consolidate the horizontal stab between the side and top views and some photos of the real thing. I also drew some divisions to make where formers will go. I drew in the outline of the fuselage where the non curved box section will be. The 3view I have shows the fuselage top as being slightly curved. Every photo I can find gives the appearance anyways that the fuselage top is straight until the rear of the fuselage where it curves up to the tail.

#5 mrittinger Jun 16, 2008 09:18 PM

Unsolicited advice.....You prolly do not need flaps. In fact, the weight you'll add putting them in will probably result in not as much effect.

If you build light, you'll have a floater on your hands and will not need the flaps.

If the retracts go forward or rearward, balance for flight with the gear UP.

If I were designing it, I'd simplify the elevator break line and make it straight, much easier linkage, and weight saved.

Good luck neat choice.
I'm looking at the B32 Dominator....

C ya at MidAm!
Mark

#6 brennanj2 Jun 16, 2008 09:25 PM

RAF would be good.
Adrian Warburton ( one of the most highly decorated of all the RAF WWII pilots) did some pretty spectacular recon missions with this aircraft based from Malta during the early stages of WWII see http://en.wikipedia.org/wiki/Adrian_Warburton
for a brief summary.

A good read is Warburtons War by Geoffrey Spooner if you want a little more detail. It seems he had some affection for this aircraft and its flying characteristics.

Good luck with the build, I will watch it with interest

John

#7 RyanPSU21 Jun 16, 2008 10:14 PM

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Thanks for the link.

I just spent an hour doing a search for potential color schemes. Lots of plastic model pictures. Not many pictures of the real thing. There is a you-tube video of one in flight surprisingly enough.

http://www.youtube.com/watch?v=3zdmrRA_yq4

Though it's way out now. This one is kind of interesting.

Thanks for the advice Mark. I might do that with the elevator. I built something before with the angle off. It can go easily if you don't hide the linkage and just shove some flexi pushrods off each side. I think even to hide it some aileron torque rods would probably do nicely. The rudder always seems to be the one I can never think of a way to hide.

The gear go rearward. I've already got a set of air retracts laying around that will go well for this. I would think if the gear is going rearward you'd balance for gearup so you are balancing at it's most tail heavy point. Similar to the balance tank empty thing for glow flying.

If I can keep the weight down flaps shouldn't be needed. Even at a heavyweight they still shouldn't really be needed at this size anyways. We'll see how they go. I can't find any pictures of the flaps down except one bottom view from the front so I can't see if they are split flaps or conventional. I suspect conventional just from what looks like hinge lines on the top surface of the wing.

I was really thinking of doing a Westland Whirlwind but then I noticed you already did plans for that so I went looking for something else.

#8 mtbrider Jun 18, 2008 03:49 AM

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I have a book with a few lines on the Maryland and this picture, I can only scan it upside down? and it has degraded a bit electronically turning it the correct way up :confused:
If you want a full quality scan drop me a PM that an e-mail address. It does look like plain flaps and that part of the engine nacelle dropped down with them.
Looking at the picture on the thread it does not look that bad, a useful shadow across it picks out some of the lumps and bumps!

Mark

#9 RyanPSU21 Jun 23, 2008 09:41 PM

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I spent the last few days roughing out the fuselage cross sections by getting the dimensions transferred from the top and side view. I think I have that part done for all but 1 or 2 tonight where I have decided since starting that I really should have a cross section.

I am starting to think about airfoil to cook up the wing on Profili. I am thinking right now that this will probably get a Clark-Y or something similar. I have thought about just going flat bottom also but will probably go for something semi-symmetrical instead.

#10 Scaledown Jun 25, 2008 07:45 AM

I'm by no means an expert on airfoils, but I've used the NACA 2412 on a number of warbirds and been happy with the results. Clark Y is good too, just not as capable for inverted.

#11 RyanPSU21 Jun 25, 2008 06:33 PM

yeah, the bombers weren't generally known for doing high speed inverted passes though.

#12 RyanPSU21 Jul 15, 2008 08:08 PM

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I've go some more work done. I have the fuselage pretty much finished up. I am working on the wings and the nacelles right now. I have the landing gear geometry worked out tonight and am staring with the cross sections. Sometime in the next few nights I need to churn out some wing ribs and spacing on Profili.

#13 ChuckA Jul 16, 2008 04:37 AM

This is a little late but back around 1948, I bought a book of Wylam plans from Model Airplane News. Two of the plans were of the Maryland and Baltimore. I really didn't pay too much attention to those plans since I was primarily interested in the P40 and P51. I never throw away airplane books and magazines but somehow that one got away. Wish I still had it.

#14 georgeg Jul 17, 2008 12:25 AM

Quote:

Originally Posted by ChuckA
This is a little late but back around 1948, I bought a book of Wylam plans from Model Airplane News. Two of the plans were of the Maryland and Baltimore. I really didn't pay too much attention to those plans since I was primarily interested in the P40 and P51. I never throw away airplane books and magazines but somehow that one got away. Wish I still had it.


There were at least three volumes in that set. I've got volumes 2 and 3. Nice looking drawings, tho I've heard that they aren't all that accurate sometimes.

#15 RyanPSU21 Sep 13, 2008 08:12 PM

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Some more progress made on this thing finally now. I got the nacelle cross sections roughed out and also the stab and elevator. The wing planform being the last major part to rough out left. Time to drag profili out soon and make the rib outlines. I took Mark's suggestion and got rid of the sweep from the elevator to simply things. For the fin and stab I plan on doing the curved portions as laminations. To limit this thing to as few parts that need to be traced and cut as possible, the stab is going to be pretty much a slab with tapering. The full scale in drawings don't show much taper except at the tip. The fin will probably need to have ribs with a foil shape to some degree. This won't be lasercut by anyone and I'm trying to design it to use as much scrap wood as I already have laying around as possible while also being as light and easy to build as possible.


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