Step 2, Build Magnum!!

194 posts in this topic

Posted

RJG,

 

Welcome to the Magnum insanity!!!

1. My wings where already set up when I bought my kit, but I did double check everything before I covered them, and the previous builder did a great job. The manual explains in detail how to set up the wings, let me know if you need a copy. There is only one adjustment on the lift strut on the left side only. Others will most likely have more experience with this subject than me.

 

2. My wings where also built with tip tanks and I eliminated them by adding the 3 false ribs, no big deal. You can find it in this post back a few months. No need for bottom false ribs either.

3. Not sure what you mean about wing tips, are you talking about tip tanks? If so, I chose not to use them because my bladder only flies for 3 hours at a time ;))

4. Check out the gear Ron and I used before going Grove, this is also documented on this forum in detail. Grove is good too, but our set up doesnt have near the recoil that a Grove will. IMO

Blue Skies,

Barry

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Posted (edited)

We have seen 3 different tips on the Magnum plans.  The trailing edge on one is slanted a little forward, the next is a short pointed tip, and the most radical is the long pointed "Finch" tip which could be a real "eye-poker".  I guess the pointed ones could be modified in most any way you wanted to make them.  There is only a slight wing adjustment on one rear strut which will help to correct any "wing heavy" tendencies in flight. 

I don't like tip tanks - I think if you need them, they would be better located near the main tanks.   EDMO

Edited by EDMO

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Posted

One wing under paint, working on fuselage covering and cowling while waiting for wings to dry between coats.

Photo Feb 27, 09 31 38.jpg

Photo Feb 26, 14 22 21.jpg

Photo Feb 27, 23 45 20.jpg

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Posted

Thx I’ll need lots of help 

so I need to have away to check the wash out if there is no way to adjust for it with lift struts . There are no tips or tanks at this point just spars and ribs.if I lay the wing on a long flat table the out board end of rear spar should be up how much ? 

What is wing heavy trendinces in flight ? one with fills heavy ?

 I thought I saw 3 different tip types the point the longer finch point and one that looked like a mk Vl stol or hh wing tip,

im wondering about no tip but an air dam just flat attached to the last rib but 1 in larger than the air foil shape 

your gear looks great  I may need more info on it , how’s it compair weight 

 

thx rjg 

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Posted (edited)

I sold my magnum manual, so I cant quote washout from that.  I hope the rest of this is correct, but it is my way of thinking about washout - Neither way would be a sales killer, IMO.

Depending on what the Avid Magnum manual says for washout, or how it was built - You could have as little as 1/2" or as much as 2" - The less washout might give you a couple more mph cruise, and the more washout the longer the ends of the wings keep flying at low speeds giving you better control.  EDMO

Edited by EDMO

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Posted (edited)

RJG

I think Barry and I are being lazy, but the wash out measurements are in the manual...Do you have one?  Barry and I both burned ours in frustration!  Just kidding...

Yes, if you are going Stol crazy I would put the flat fences on the end!  It would look cool...like the Kitfox 7

I would say keep the tips if mph is your goal...go with fences if STOL is your plan.  Then compare the 2-3 mph difference in the end and either celebrate or morn...

 

Ron

 

Edited by RDavidson

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Posted (edited)

RJG

I think Barry and I are being lazy, but the wash out measurements are in the manual...Do you have one?  Barry and I both burned ours in frustration!  Just kidding...

Yes, if you are going Stol crazy I would put the flat fences on the end!  It would look cool...like the Kitfox 7

I would say keep the tips if mph is your goal...go with fences if STOL is your plan.  Then compare the 2-3 mph difference in the end and either celebrate or morn...

 

Ron

 

I don't see how the flat fences can help STOL - You lose lift by not having the tips on the wings.  If you just want to look "KOOL". then fences are the current fad - just like pink and gray was the fad in the 1950s - I had the clothes then, and a matching 1956 Pontiac!  ;<)  Thankfully, you don't see or wear that now - unless you fly nosedraggers!   Thanks JIM for reminding me! - Ha!  EDMO

Edited by EDMO
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Posted

Today was baggage day, I hate baggage!! Anyway, I am ready to wrap this taco.......

Photo Mar 01, 19 11 21.jpg

Photo Mar 01, 22 30 03.jpg

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Posted (edited)

RJG

I think Barry and I are being lazy, but the wash out measurements are in the manual...Do you have one?  Barry and I both burned ours in frustration!  Just kidding...

Yes, if you are going Stol crazy I would put the flat fences on the end!  It would look cool...like the Kitfox 7

I would say keep the tips if mph is your goal...go with fences if STOL is your plan.  Then compare the 2-3 mph difference in the end and either celebrate or morn...

 

Ron

 

I don't see how the flat fences can help STOL - You lose lift by not having the tips on the wings.  If you just want to look "KOOL". then fences are the current fad - just like pink and gray was the fad in the 1950s - I had the clothes then, and a matching 1956 Pontiac!  ;<)  Thankfully, you don't see or wear that now - unless you fly nosedraggers!   Thanks JIM for reminding me! - Ha!  EDMOo

Ed,

I’m not going to argue aerodynamics with you, because all I know is I empty my wallet and it must make me light enough to fly.:lmao:

But something isn’t right about your fence logic, because Kitfox wasn’t doing it for looks, they were testing it for better STOL capabilities...I saw it first hand at their factory...

I said I wasn’t going to do it, but fences direct airflow just like vg’s do, so why wouldn’t they affect lift?  I think we are actually arguing the same side of the coin here...improved airflow helps both speed and lift, minus the added drag of course.

And if we are talking about 3 mph who gives an F!  I hung 31” tires on mine that lost me 15mph probably! 

Edited by RDavidson

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Posted (edited)

Ron,  All I am trying to say, is that if you make the wing shorter by eliminating the tips, then you are going to lose lift curve which hurts STOL.  That's like making a Speedwing out of a STOL or HH wing. 

In regard to the new Kitfox wing with flat plates, I don't know if the wing was lengthened to make up for the removal of the tips.  This may be a lot of sales hype, like Cessna used when they put the slanted tail on their birds - It looked a lot sleeker or sexier than the upright tail but was not as efficient according to what I have read.   

I have some info on flat plates, but it has more to do with vortexes and drag than lift, so I wont clutter the STOL conversations here with that. 

EDMO  

Edited by EDMO
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Posted

Ed,

we can agree that losing surface area doesn’t help lift...So same size wing, one with the Magnum eye gougers, and one the same length with a flat fence...which one does what?

I heard the finch tips were to help flow the air off the tips, and project the tumble away from the tips?

flat plates/fences keep the air from rolling off the side edge and funnel it off the back?

Both promote lift by keeping airflow stable, and induce a little drag as well...right?

Ron

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Posted (edited)

If flat plates were the best thing for lift, and reduced drag, don't you think they would be on all Boeing planes?  Evidently, the Boeing engineers know that winglets do a better job than any other kind of wing tips.  Maybe that is why Bert Rutan put them on his designs?  I rest my case.  Oh yes, I think the Finch tips would win over flat plates for overall performance.  I've got a design book written by an engineer and test pilot that goes into a lot of technical detail about all the tips but I hate to try to post it all on here.  EDMO

Edited by EDMO

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Posted

Chief-

Please bare with me on silly questions, learning curve be mighty steEP! Lol

Im guessing these two cylinders are header tanks. Why 2? Thank

A4F1E6FB-A5C1-4EAF-938F-590EB206EC27.jpeg

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Posted

Chief-

Please bare with me on silly questions, learning curve be mighty steEP! Lol

Im guessing these two cylinders are header tanks. Why 2? Thank

A4F1E6FB-A5C1-4EAF-938F-590EB206EC27.jpeg

Yes, they are header tanks. One for each wing tank. These prevent getting air pockets in the fuel system from fuel sloshing in the main tanks. The reason for two are because you can swith tanks with the fuel valve. Search this site, I'm sure there is much discussion on this and other fuel related topics. Happy building!

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Posted

Great day yesterday with the help of friends. Got one side covered and more coats of Poly on the other wing.

Photo Mar 02, 15 50 27.jpg

Photo Mar 02, 14 55 13.jpg

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Posted

If flat plates were the best thing for lift, and reduced drag, don't you think they would be on all Boeing planes?  Evidently, the Boeing engineers know that winglets do a better job than any other kind of wing tips.  Maybe that is why Bert Rutan put them on his designs?  I rest my case.  Oh yes, I think the Finch tips would win over flat plates for overall performance.  I've got a design book written by an engineer and test pilot that goes into a lot of technical detail about all the tips but I hate to try to post it all on here.  EDMO

I said they induce drag!!!  So your argument is because I don’t see them on Boeing and Rutan aircraft that everybody else is doing it for looks?  None of those are STOL aircraft!!!!  The want to travel fast through the air, meaning less drag, meaining they don’t want a fence hanging up in the air 3”.

I’m just asking that we don’t say that people are just doing it for looks!  There is obviously an advantage in slow flight.

I don’t know how dusty that book is that you have, but technology changes and everything stol is being revisited.

I didn’t want to get into this discussion in the first place because the only formal aerodynamics training I have is Air Force and we overcame drag with thrust and cared about flying at 600+ mph.  I didn’t discredit your claim about the finch tips, I just think fences might hold some merit other than decorative ornaments acting as weights on your wing.

Guys on this forum listen to what you have to say ED, I was one of them when I brought this topic up before building my wing, and I chose finch tips partially because of your theories and partial because I was tired of making mods.  Then I toured Kitfox and saw them experimenting with fences!

Nobody ever made an advance in technology by listening to “it can’t be done” or “somebody tried that already!”

Wright Brothers...I rest my case (absurd)

 

Ron

 

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Posted (edited)

Ron,  I don't know what Kitfox has discovered with any testing they have done on using the flat plates.  I have a skeptical approach to this because sometimes "gimmicks" are used to boost sales.

I am not an engineer, but I have read more than one book on Aerodynamics, and I stayed at Holiday Inn Express one night!  ;<)  As I understand it, the winglets that Boeing, Rutan, gliders, ultralights, and others are using make the wing perform like it had a longer span without adding length to the wings, and a longer span means more lift to get them off of the ground quicker (STOL?), and I guess they produce less drag to save fuel. 

One thing I read about the flat plates, which are actually old technology tried many years ago, was that unless the plates have a height equal to the wing chord they don't help prevent the high pressure from the underside from coming over the tip and producing a down pressure on the topside, the vortex producer, actually decreasing STOL ability.  I have never understood if that height would be half on top and half on the bottom of the plates, but guess that info must be somewhere.  Tests have shown that the vortex is strongest at high-lift situations, such as on takeoffs.

The one thing that I have read that would decrease drag on the Hoerner type tips, and possibly on your Finch tips, is that if they are angled about 6 or 7 degrees with the trailing edge being a longer span than the leading edge, that they will produce less drag by shedding the vortex farther away from the wing, but how much difference I don't know.  But to quote Leni, and maybe some others:  "What difference does it make on our draggy planes?"   EDMO

Edited by EDMO

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Posted

Uncle........

RJG I guess your Magnum needs winglets...

Best of luck,

Ron

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Posted (edited)

Uncle........

RJG I guess your Magnum needs winglets...

Best of luck,

Ron

There is nothing wrong with the Magnum as it was designed, like a larger Avid - It just needs to be built, flown and enjoyed, IMO.

But there were or are some ultralight Winglets for sale on ebay - Not sure about how that would work!  EDMO

https://www.ebay.com/itm/NICE-Set-of-Ultralight-Aircraft-Homebuilt-Experimental-Rudders-Winglets-EAGLE/122756866135?hash=item1c94e12057:g:C-sAAOSwqU5Z2oJ8&vxp=mtr

Edited by EDMO

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Posted

Chief-

Please bare with me on silly questions, learning curve be mighty steEP! Lol

Im guessing these two cylinders are header tanks. Why 2? Thank

A4F1E6FB-A5C1-4EAF-938F-590EB206EC27.jpeg

Yes, they are header tanks. One for each wing tank. These prevent getting air pockets in the fuel system from fuel sloshing in the main tanks. The reason for two are because you can swith tanks with the fuel valve. Search this site, I'm sure there is much discussion on this and other fuel related topics. Happy building!

thanks—was curious. Mine only has the one on the port side. I’m loving this thread BTW...excellent job of documentation

take care

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Posted

Hi guys thanks for the info 

I’m just trying to get my ducks in a row , the kit in Washington is in the adoption process and going to move to pa . There is a biuld manual with it, so I’m going to be a busy boy 

Thx rjg 

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Posted

Taco is wrapped.....

Photo Mar 03, 16 36 41.jpg

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Posted

Things sure do move along quicker when you have some helpers, looking good!

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Posted

Ready for tape.....

Photo Mar 05, 17 53 57.jpg

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Posted

Ed, when did you become so against experimenting.. That's pretty much like saying your leading edge mods are stupid and wont work because that is not the way kitfox or avid designed them.  The tip plates keep the air from spilling off the wing tip and they di indeed help with STOL.  Having less washout not only helps with STOL but will get you a few more MPH either.  A lot of this comes down to looks.  Some people don't like the looks of flat plates, fine, don't use them but to say its a gimmick for sales is not fair, I know they work, I have just not used them on my avid yet as I am too busy with other things to keep doing mods to the plane.

:BC:

 

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