Mini Flash Speed Wing Build and Fly - RC Groups
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Jul 18, 2003, 05:44 PM
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Darren Hintze's Avatar

Mini Flash Speed Wing Build and Fly

Hello All,

I must be one of the only U.S.-based old timers without a plane from Mountain Models but that's finally changed!

After researching options (I wanted a balsa 35-ish inch WS pattern-capable to replace a Tangent) I found the MF/Speed Wing seems to fit the bill perfectly!

I only know of one other E-Zoner flying this plane so I thought I'd post "build and fly" infomation about this.

First off, here's my planned power and performance:

Power System:
Mega 16-15-5 in GWS 2.14:1 (EPS400-A ratio) gearbox.
11x7E APC prop
9 cell 1100mah HECELLs (perhaps 3s2p lipo also)

I expect extended vertical, near 1:1 thrust and plenty of speed to pull the plane through competition-type patterns including 2, 4, and hopefully 8 point rolls, knife edge, Cuban-8's, Hammerhead stalls, etc.

I already have some planned modifications.

The MF wings are in two removeable panels with individual servos. I plan to build in the wings and convert to single aileron servo. The dowel spars will likely be replaced with CF Rod. The wing LE will also have some kind of CF reinforcement, either in the form of a rod replacement of the balsa stock or CF tape. The hollow balsa motor mount will also be replaced with solid basswood (I think the Mega may rip the stock one apart).

I plan to belly land so the stock LG will not be installed. I may add a snap-on LG (borrowed from the Tangent or Live Wire) system however.

I also plan to cover with Ultracote to add a bit more strength -- and because I prefer the material.

Because I can ditch the LG, I think the weight of my slightly beefed airframe should be very close if not lighter than the stock w/o gear... slightly heavier with.

Initial building review to follow!
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Jul 18, 2003, 05:51 PM
Tight is Right
Darren Hintze's Avatar
Building the fuse...

WOW is about the only word to describe it. I've built probably 50 balsa RC kits over my 14 year carreer and this one falls together with the best of them. I had a little time at lunch with the plane in my car so I thought I'd break it out and look at it.

The first two instructions were just gluing fuse bulk-heads together so I found the glue and did that.... well... I couldn't resist continuing through lunch and by the end I had nearly completed the entire fuse! I had just the box to work on and the pieces aligned themselves perfectly!

Doug's laser cuts the parts so well the pieces just fall out of the wood smooth and ready to build. The instructions were easy enough to follow that a first time balsa builder could very easily accomplish this so far.

If the rest of the plane goes together this easily I'll finish it (minus radio gear) this weekend and should be flying by next weekend (the goal!)

Jul 18, 2003, 05:55 PM
Size Matters!
RocketRob's Avatar
Good project.
What is the diff between wings? Symmetrical? Area?
I would immagine your's with the mega motor won't be tail heavy.
Jul 18, 2003, 06:44 PM
Registered User
Gaz's Avatar
Hi Melf,

Looking foward to the pics of the build as I have a new fuse kit to build for my MF speed wing and have been thinking of getting rid of the landing gear, it will be powered by a hacker B20 15 L and Model Motors 3.86:1 planetary box.

Jul 22, 2003, 01:09 AM
Tight is Right
Darren Hintze's Avatar
Okay, building started -- a few notes:

First, after starting building the wing, I thought is was thick for a speed wing. A little later, I notced there was a separately wrapped group of parts... the Speed Wing. Apparently Doug sent me BOTH wings with the kit.

I owe you some money Doug.

Anyway, after thinking about it, I decided it'd be nice to build a hot aerobat powered by 9 HECELLs for the Speed wing but also build a lighter, slower 3D plane for 2s2p LiPo's for flying around the neighborhood.

This change in strategy will alter some of my mod plans. I no longer will do a single servo redesign nor will I fix the wing. Everything will be stock except the CF rod LE on the speed wing and CF Tube LE on the 3D wing.

After three hours of building, the Fuse is almost finished and all four wing panels are complete with the exception of the LE of one side of the Speed Wing (I didn't have enough of the right sized rod).

The plane falls together. I think you'd have to really try to build it crooked. The wings especially almost snap together then are glued at the seams with thin CA.

I'll take some pics of the wings and fuse tomorrow to show progress. I should finish the framing work tomorrow and begin covering Wed.

Jul 22, 2003, 01:16 AM
Tight is Right
Darren Hintze's Avatar
Oh, one question for you other MiniFlash owners....

My one concern with this plane is the wing joining method. I'm very concerned with the higher speeds and weight of my plane the wing joiner design will not be strong enough. I'm considering putting some CF rod spars through the wings to aid.

What have you all experienced?

Jul 22, 2003, 11:47 AM
Mountain Models Wannabe
CoClimber's Avatar

You don't owe me money for the second wing. It was going to take a while to lay out a speed wing kit so it was just faster to send you the stock kit and include the speed wing option. I hate sitting on orders.

While I don't think you could break the speed wing, I'll do some stress tests to verify that.

Jul 22, 2003, 12:11 PM
Tight is Right
Darren Hintze's Avatar
Hey Thanks Doug!

Let me know how the testing goes. My little aerobats can pull +/-15g's. Mine will be around 20oz AUW so that's the stress I'm looking at.

Your design lends itself well to putting an extra tube in the wings (where the holes are anyway) then running an extra CF rod through for safety. Because this will add such a small amount of weight for the plane I'm building, I may do it anyway.
Jul 22, 2003, 12:48 PM
29 rods from you in western WI
Karl Bē's Avatar
Melf, I was concerned with the wing joiner, and I did notice it loosening a bit. I found the nut wasn't holding, so I replaced it with a nylon-insert type locknut.

I considered adding two more bolts near the fuse sides to lock it down, but figured that what I'd gain in leverage I'd lose in material strength. What I did instead for peace of mind was to wrap a small zip tie around each end of the spar sandwich near the fuse sides.

Any pictures yet?

Jul 22, 2003, 03:27 PM
Tight is Right
Darren Hintze's Avatar
Hey Karl...

Great idea. I have lots of zip-ties I could use to help lock the wing in. I had bad pictures in my mind of the "one bolt that holds the whole thing together".

Too many cartoons I guess

Jul 25, 2003, 03:32 AM
Registered User
Gaz's Avatar
Melf, I have had a spar break due to extra wing loading of a nicad pack of 8.9oz.

There was also 2 bolts in joining point but it fractured at the end of the wing, also there was a small nick in the solite I had noticed previously, and after was a large tear, it may have been extra loading as well.

I don't think this was from the impact as the half wing seperated 100ft in the air and just floated down.

I've never had a problem with the wing using kan and he cells doing high speed snap rolls ect.

On the next build I might extend the leading edge through the fuse and pin it and also use a thicker ply spar joiner.

But as I mentioned before I've never had a problem with other battery's and as standard It's very strong.

Jul 25, 2003, 10:27 AM
Tight is Right
Darren Hintze's Avatar
Hi Gary,

Yeah, that was exactly my thought but my LE rods hit the fuse right at the LG bulkhead. I am running some small rods through the back portion though.

Back to One Servo...

After building the wings and most of the fuse, I am going back to my "One Servo" conversion. After thinking about it, there are many compelling reasons for this modification including:

1 - Using one $15 9g servo vs Four $25 6g servos for the ailerons in two wings.

2 - Less strain on the BEC as 4 servos taxes them already and I may want a fifth for retracts on the 3D wing.

3 - No messing with y-harness wiring when swapping wings.

4 - Lighter weight.

After looking at the plane, I'm quite certain I can mount a single aileron servo right in front of the rudder/elevator servo tray and run control rods out the side of the fuse to the aileron horns. I'll use snap-on clevises so I'll only need to unsnap and resnap those when swapping wings.

One challenge will be the Speed Wing aileron, stock, sits about 1/2" further back than the 3D wing aileron (the speed wing has smaller ailerons). I'll solve by cutting the TE of the Speed wing and making the aileron larger near the wing root.

Now that the woodwork is nearing completion, I'm confident this modification will work.

Jul 25, 2003, 11:16 AM
Tight is Right
Darren Hintze's Avatar
Here are some pics of the built up wings with the CF and fiberglass rods. The first is the Speed Wing with a Fiberglass LE rod (I didn't have CF of the right size) and a CF added spar aft of the main spar.
Jul 25, 2003, 11:17 AM
Tight is Right
Darren Hintze's Avatar
And the 3D wing with CF Tube LE
Aug 03, 2003, 07:14 PM
M0unt@in M0del$ minion
turbojoe's Avatar

I just flew mine today with the speed wing. It's awesome! I much prefer it to the 3D wing. It's considerably faster and very, very responsive. Inverted flight required almost no down elevator. It was a ton of fun. I flew it with an Astro 10 turn and 3x1200 E-Tech's. The only problem I had was with orientation. I need to do some re-covering so I can see it better. My fault. Not the planes. Have you finished yours yet?


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