Nose gear modelling, and F22 position

[Justin]

I have been modelling the nose gear, and am moving on to the rollover structure. Here is a STP file of my nose gear. The castings are pretty much guesswork. It is clear that the extended nosewheel axle position in the attached sketch is impossible to get to if the section views A7 and A8 are followed. My gear and worm pitches are correct, but the actual tooth and work geometry are guesswork based on the Boston Gear data. There are still some things to add. Note, that the worm drive shaft hole in F22 should be offset to the right, and not on the centreline, as the plans sketch of F22 shows. I expect there is a CP newsletter correction somewhere for this.

Now I find some anomalies in the position of the F22 bulkhead. Perhaps it is resolved in corrections in the CP newsletters, but I have not read all of them yet. Page 5-1 shows a side view with 103 inches between the aft side of F22 and the forward side of the firewall (F.S.125), but the forward side of F22 is at F.S.22  .  It probably makes no difference to performance how it is built, but the sketches should be more correct. The pilot's seat back position is dimensioned from F22.

It is all work in progress.

Nosegear.zip Open-EZ r5 A3.tif

Edited September 23, 2020 by Justin
'forgot a few things

[Kent Ashton]

Very nice but a couple of ideas:   Most people seem to prefer the wilhelmson electric nose  lift which bolts in but barely leaves any space between the nose lift motor and the canard.   That makes it hard to add a cover over the NG 30s to keep out drafts.  It would help to make the NG 30s taller so the nose lift could be sealed with a simple cover over the NG 30s.

Most people lengthen the nose but the pivot point for the NG strut is kept the same as for the stubbier nose.   With a long nose, the pivot could be moved a couple inches forward and down.   That would allow a more symmetrical nose profile with the longer nose, allow more space for the Wilhelmson nose lift below the canard, and give a bit more positive longeron angle which helps with rotation.
 

While you’re redrawing the fuselage, you might as well incorporate the longer nose with a space for a battery as far forward as possibly.   It is needed to balance the  larger engines most people use.

I believe the 103” dimension is only the length of the side foam, then the f-22 and firewall bulkheads are attached later

Edited September 23, 2020 by Kent Ashton

[Justin]

Hello Kent,

I like your ideas. You also suggested earlier, some interesting extra fairing upstream of the engine cowls, and I have been working with that too, and it looks good. I will go for armpit cooling inlets with louvres in appropriate positions in the top cowl.

I don't really see the point of electric nose gear lifting. The standard system seems to be perfectly adequate. I would go with the standard manual system. KIS. Keep it lighter.

I think the NG30s can be improved with a small modification. They seem have a load path to F22 that is not properly reacted there. Hundreds of flying EZ have proved this is not a problem, but it does look odd to me. I think the nose gear loads are probably not large, and the structure can handle it anyway. I think the nose skin structure also shares the nose gear loads. It is weird that the NG30s don't go high enough to have a seal, but maybe it is unnecessary.

I have lengthened the nose , but with the nose leg pivot in the standard position. The underside profile remains standard. Any lengthening of the nose loads the canard more from the weight point of view, so is it wise to also move the battery forward ? The engine I am working with is the UL390i. It is about the same weight as the 0-235, and a bit more powerful,, with slightly lower frontal area. I lengthened the nose only 6" to reduce some aerodynamic down forces I think come from the upper surfaces of the standard nose. Moving the nose leg axis down a little could be beneficial, if it reduces the unstick speed on take-off, but I will work with the standard axis position for now.

There is a dimensional conflict with the side foam. If that is 103", and the F22 frame profile goes to the side skin, page 5-1 must be wrong. I am not too bothered by this. The design is tolerant to it, but if the Open EZ project wants to make sense of all the design information, it should be resolved. The 103" dimension should probably be reduced by the thickness of F22, or the aircraft gets stretched by  the thickness of F22.

Cheers,

Justin

[Kent Ashton]

I agree about the manual system but nobody is making them anymore.   Not hard to make, though.

it is very common to lengthen the nose.  On my O-320 EZ with a longer nose and battery there, I still had to use 10-15# up by the rudder pedals to get what I considered a safe stall warning in the form of canard bob—and I am not a little guy—225#.    With a lighter engine you may be OK

[Justin]

That's interesting, Kent. I am not so light either. I will be having a very minimalist panel with remote NAV, COM, XPDR units controlled from a glass PFD/MFD. I could use their installation position to tune CG position.

The cockpit will be further de-cluttered, as the engine requires no mixture or carb heat controls. The aircraft will be a fully de-cluttered VFR machine, so any reduction in instrument/controls weight should not be overlooked.

[Kent Ashton]

I see that the UL390i is maybe 60 pounds lighter than an O-320  (220# vs 280)  (  see https://www.supercub.org/forum/showthread.php?31942-O-320-O-360-What-do-they-really-weigh ) but do you really want to pay $29K for an engine?  You can probably buy a mid-time O-320 for $15K--half the cost.  By the time you get to needing an engine, the price for the UL might be over $30K.  It's up to you but I would look at how many they are selling.  The ULs do not seem to be used on a lot of airplanes   https://en.wikipedia.org/wiki/ULPower_Aero_Engines

If I were to build another EZ, I'd plan for an O-320 again.  It will be just as much fun and a lot cheaper.  Yeah, I am a cheap guy  🙂

I saw that the guy who built an EZ with a UL put it up for sale for a short time at $95K then took it off.  I'd like to know what happened there.  I see that he had some small problems with the engine  http://www.mykitlog.com/users/display_log.php?user=jenatepilot&project=2121&category=9305&log=258399&row=51   Haven't read much about him lately.  Came across this page with UL owners.   http://www.myulpower.com/p/blog-page_13.html

[Justin]

I think UL may be pricey your side of The Pond for the same reason that Lycomings are more expensive on our side. I think there is much more general aviation in USA, and you have good sources for new American engines, and parts. I reckon the sheer volumes of engine equipment sold over there means there is more competition, and lower pricing. It's possible I would use a Lycoming if I was over there.

Over here, I have not owned a UL myself, but have helped on a few projects with installation and cowl design for ULs. I have found UL Power helpful in this too. It was interesting to read of the issues the EZ builder had over there. I'm sure it does not do UL's reputation any good over there. 'interesting to see that EZ has a 3 bladed propeller. I have not heard of serious issues among the UL owners I know.  I will have a good look at the EZ builder's site you linked, when I get home from the office.

UL are not the big one for experimentals here. Rotax are. I find them a bit complex, but incredibly compact, and quiet externally. I have flown with a Rotax, and it was a bit buzzy in the cockpit. I prefer the direct drive, and the simplicity of the UL engines. Also, they are not far from where I used to live, in Belgium. I could visit them on regular travels through Belgium (in normal times).

 

[Voidhawk9]

Nate Mullins has the UL powered EZ, and he did resolve the issues eventually. He can provide guidance regarding installing them in an EZ if you want it.

[Justin]

40 minutes ago, Voidhawk9 said:

Nate Mullins has the UL powered EZ, and he did resolve the issues eventually. He can provide guidance regarding installing them in an EZ if you want it.

Eeek !  Thanks, but websites like that repel me almost instantly. It is interesting to look at the build website though. I should try to contact Nate.

[Crspy]

Nate also documented his UL power experiences here http://www.myulpower.com/

[Justin]

That looks interesting. Thanks for the link.

[Justin]

9 hours ago, Crspy said:

Nate also documented his UL power experiences here http://www.myulpower.com/

Excellent information at Nate's ULpower site. Thanks again for that link. I am surprised Rupert at Hercules didn't get back to Nate. I have worked with Rupert on a Spitfire blade. Rupert uses a design program from Sweden, by an interesting chap called Jan Carlsson.