doxilia

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Evening Gents!

I thought I'd start a new thread for a 77% UFO which I'd like to build for a piped SuperTigre X25.

It would have trike Robart 600 mechanicals and 7 servos (3 in wing and 4 in fuse). I started with Rainedave's 66% plan (version 3 of this build thread), blew it up some and have been making some changes. Unfortunately I don't have access to David's DXF or DWG files so I've been working on a vectorized layered PDF file. Unless I can obtain the files from David, I might have to scratch build from these plans although Ideally I'd like to have it laser cut.

There are a couple of details which I haven't been able to resolve. If there are any CAD guru's who would like to lend a hand, we could get some kits laser cut and expedite the build process. I'd be happy to repay any assistance with a short kit from the cutter if that is of interest.

I'll post the state of the plans I've been working on for comments. For reference, the scaled down BHE plans are also posted. Note that there is a slight discrepancy between the BHE UFO 25 and the CAD UFO 25 with the latter being just a tad larger. The goal in scaling the CAD plan was to obtain a wing with a specific area for a loading in the 18 oz/sq ft.

Note also that the fuse top view does not match the former width as these were widened to obtain the desired space in the fuse. All formers were scaled in equal fashion width wise but F3 need not necessarily be that wide. In fact, F3 could be substituted for 1/4" square stock bracing and spread to the fuses natural airfoil as it tapers to the 5/16" tail (1/16" center sheet missing from tail junction on plans).

A PDF of the plans can be posted for anyone interested.

David.

doxilia

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The BHE plan wouldn't upload. Here's another try.

David.

doxilia

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I just had a flash idea and think I may have figured out how to produce the non uniformly located ribs 3 & 4 without too much fuss. The 4 (maybe 5 would be better) stab ribs also need to be done.

David.

Roguedog

Hey David.

I'm game for a swap, eg cad services for a shortkit. I'm working on drawings for a Ursa Major 25 right now. Just stated it today as a matter of fact. If you can email me the PDF of the correct size I can turn it into a tif that can be imported into me cad app.

Bryan

Rendegade

Dave, seems you're missing some room for the nosegear, have you thought about the mounting for that?

doxilia

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Hey Bryan,

glad to hear you're interested. I'll fire the PDF plans to you. Please just send me a PM with your email address as I might have misplaced it.

Rendegade,

yup! That was the first thing I noticed while sorting out the gear on the plan. In truth though, there probably is the same issue on the full 60 size. The main problem is the shallow fuse depth of the Dirty Birdy and the UFO which share a very similar fuse. I believe there's enough length (5"), although the mains and the nose gear length don't necessarily match up at the moment as drawn. I left a healthy 4" from pivot to ground on the mains which translates closely to the same required amount for the NG. If that's correct, then I should have enough space length wise in the FW to F1 spacing for 9" prop clearance.

The height is another matter. As mentioned, it is shallow, but a 1-1/2" wheel should fit if the 3-3/4" long tank is positioned just aft of the end of the 5/16" solid nose intermediate sheet and the 5/16" square stock behind it. This allows the tank to be flush against the top 5/16" sheet which provides another 5/16" of clearance. The wheel should tuck in underneath the tank without it protruding more than 1/4" perhaps from the bottom of the fuse.

This is the main reason that I modified both the BHE and David's CAD plan to terminate the top nose intermediate sheet just where necessary in order to fit the tank in its bay. Although the tank is 1-3/4" tall there might potentially be another slimmer tank that could be used (maybe cylindrical or oval). Another possibility of course would be to make the overall fuse a little deeper but this might involve introducing a belly pan on to the wing and a rear fuse extension - I'd rather not do that as it will change the lines of the UFO. On the other hand, since the width has deviated from the 60 scale (in order to provide space), it might balance things out nicely. I guess a UFO with a belly pan would not quite be a UFO anymore.

Much to sort out still. I'm sure Bryan will have some comments too.

David.

BERUSTY

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UFO build...yippeee!

The UFO was my first glass/foam/paint project. I flew it to best Jr at the 1979 NATS...I believe I was the only Jr...anyway, great life experience.

Regarding the retracts...Horizon and their E-Flite brand has a very cool set of electric retracts for 15-20 size models that I played with at the recent Chicago Hobby Show. They are or soon to be released in conjunctionwith their E-Flite Bonanza. The units will be around $90, plug directly into the retract outlet of your RX, have low current drain and a nifty stall feature.

Here is the photo which I posted previously on the Phoenix 7 by Horizon thread.

I intend to use the little jewels in my Bridi Tweety Bird powered by the K&B .19 as the original or with any luck win a K&B .21 rear exhaust.

Rusty Dose
Team Futaba

doxilia

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Rusty,

Maybe a little premature but thank you for the enthusiasm!

Those gear are too cool - I'll have to have a set. If I'm as thrilled as I am with Multicons, I might just use them instead - two servos less! So where's the amp? Built into the units? By stall feature do you mean they rotate slowly or do they come to a rest with a slow down at the end?

Any idea on weight? The Robart 600 mechanicals with two light servos are 120g (plus linkages and servo mounting hardware) - figure 150g or 5.3 oz AUW for mechanicals. Are those 50g a piece or less?

David.

doxilia

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There we have it:

http://www.e-fliterc.com/Products/De...ProdID=EFLG110

5 oz per set!

That was quick.

David.

P.S. That means a finished model all up at 45 oz without gear...

doxilia

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Mmm... yup! Gotta have a set of those asap!

Here's the manual.

David.

doxilia

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Bryan,

I just sent you an email with the UFO 25 plans and other info (PM'd too).

The Ursa Major 25 - cool! Is that a Yioshioka design? I know Jason (zubba) was building one along with an MK Curare 20 last winter. Haven't seen him around here for a while.

If you can shoot me that plan, I'd love to take a look at it.

Cheers, David.

P.S. BTW, take a look at the electric retracts in the couple of post above. I think I'll go with these for the UFO as it is a tight squeeze - 2 servos less. Nice. I suspect, like other E-Flite retracts I've seen, that these use Robart like bodies (same dimensions as the 600's) with an E-Flite electric mechanism where one typically finds a pneumatic cylinder. In other words, they should fit and be of the same size if using the dimensions of the Robart 600's. I've shown it on the wing but not on the fuse for the NG.

doxilia

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A few minor changes to the fuse plan showing some parts for reference.

David.

doxilia

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Further changes to the fuse plan. Almost complete - just a little dimensioning that needs to be confirmed and it should be ready for laser cut layout. I'm still working on the wing plan although that one too has come a ways.

The expected date to have this cut is early February.

David.

Free Bird

Hey Dave!

I was just drooling over the UFO fuse plan. Now I've got to wipe up my keyboard! Are these plans ready to go? Can I get a set if they are? TIA!

FB

doxilia

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FB,

glad to hear this is salivating! I tend to keep a bowl handy on the desk just in case...

The plans are not quite ready yet. As I mentioned, dimensioning of a few things remains to be checked. I'd like them to be 100% consistent. Then of course, without the wing/stab plan, they're not of much use. When they're ready, I'll drop you a line.

I intend to have it laser cut so you might be interested in one of them packages too!

David.

doxilia

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Tom,

thanks for your encouraging PM!

It only seems fit to share what others have shared with me. I'm a bit of an advocate of the policies of the Free Software Foundation and although I'm not really much involved with programming anymore, the model seems most appropriate for our hobby - and perhaps more so with the classics.

As mentioned in the previous post, the plans are not quite ready. I wouldn't want anyone building from them yet as they are not consistent. They change a bit from day to day on and off as I adjust for my latest thinking. Originally, I had contemplated a piped ST X25 while now I'm thinking more along the lines of an OS 32 SX as shown. This requires moving the FW back by 1/8" which actually changes a whole lot of stuff on the plan. Now, most engines in the 25 to 32 size (maybe 35) should fit without problems. Clearance for the prop also stands at 5.5" but I'll probably increase this to 6" to allow a 10" prop to be swung comfortably. The retracted nose gear space is now there to be had.

The model is on the larger side for a 25 and while the wing on the UFO is small by design, I keep looking for ways to reduce weight in order to bring her in at a loading of under 20 oz/sq in. Things like the fuse top and the thickness of the vertical might still change but I'm basically converging on a final plan.

The flying surfaces have been tricky as I'm not very adept at Profili and some tweaking to the airfoils might be required once the plan is finished. Joe's designs were unusual in that he had both the LE and TE of the wing tapering. The tapering TE makes things somewhat tricky.

But I digress...

I'll keep the thread updated as I progress toward the kit.

Thanks to all for your interest.

David.

Free Bird

Very cool on all accounts David, keep plugging away at. I'm impressed by your skills and appreciate your efforts!

FB

pitstop000

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David,
Any updates?

doxilia

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Paul,

Yea,

but for some unknown reason to me I'm working on three plans at a time. At the moment, I'm working on the CAP plans. I trust I'll get my head around the UFO by Sunday evening to finish it up and get it cut next week. There are only some minor things to finish up on the wing plan aside from my debate on wood stock for the fuse.

I've been thinking about the plan and realize that it is not as light as it could be. For the sake of allowing a more oval shaped fuse I'm going to leave it as is with more of a "semi-classic" airframe design. Essentially the top sheet and bottom rear sheet are both 1/16" thicker than they could be (5/16" and 1/8" rather than 1/4" and 3/32"). This will require some more elbow grease but the results should be more pleasing allowing the rear to be sculpted into a "glass like" shape. I've also been changing things around in the bottom front to make for a simpler, less expensive cut.

I hope to have a more concrete update soon.

David.

Roguedog

David.

I was just looking at the your plan of the UFO25, excellent work. I'm curious. Is this UFO is going to have an anhedral stab like 60 sized UFO?

Didn't see if it was shown on the plans.

Bryan

doxilia

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Hey Bryan,

sure, why not?

The wing plan shows the wing/stab dihedral/anhedral detail. 1.25" and 0.75", respectively. These are scale measurements.

David.

Roguedog

Hey David.

I see it now, was looking at the fuse side view plan not the seperate wing plan. Awsome and very cool.

Bryan

doxilia

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I have received a few PM's and emails lately about this project so I thought an update would be in order. I'm in the throws of finishing things up and should have something more concrete in the following couple of weeks. I'd like to take the opportunity to thank Bryan for his help with the rib profiles on both the wing and stab as I went through a few different iterations of layouts until I was satisfied with the reduced scale re-design.

I plan to get a first kit cut to evaluate it's un-built weight and consider whether it might be possible to shed a few ounces by changing some of the sheet stock. The fuse sides and top are the two primary thicknesses that I'm considering revising once I receive the first cut.

David.

EscapeFlyer

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WOW!


Brian

R_G

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This is Very Cool! [sm=thumbs_up.gif]

I'm hoping this becomes a build thread eventually!