ChiefK

O I've already set it up with retracts on a 3 gear set up. The biggest problem is that I built it with ambroid, which is what we used back then and the tail was knocked off just in front of the last bulkhead before the vertical stabilizer and now that I look at it that was definitely a weak spot and that it will take some reinforcement to this area to make me happy. I will need to go throughout the plane now to make sure all is not weakened over time. A buddy of mine use to fly his with the gear fixed and it flew ok, but planes fly much cleaner and coast through maneuvers much easyer when they have retracts.
Terry<br type="_moz"/>

I certainly don't disagree about the improved flying qualities of a "gear up" pattern plane. What I need is a SPA"legal" pattern plane, and whatever that is, it will not be allowed to compete with gear up, so may as well save the weight and practice the way I'll have to fly in any SPAmeet - gear down and locked. I particularly like the Mustang X because "taildragger" isthe P-51 Mustang'snormal configuration. It should handle well on marginally improved grass runways and look good too. Does anybody know if there are foam wings for the 65" version available out there"?

Looking at the plans, I see a marked similarity in how the Mustang X tail assembly is fitted and how the tail assembly of the Tsunami I'm currently building is configured.That wasbeefed up with 1/2" triangle stock under the stabilizer and a contoured balsa block filet from the ahead and above the stabilizer. Should be pretty solid.

Should be able to add the triangle stock inside the Mustang X fuselage under the stabilizer and maybe add a dowel from the leading edge of the stabilizer into the top balsa block forward of that area.

ChiefK.

Well I checked with SPA and I've learned that even though the Mustang X is on their "approved" and "legal" airplane list, I cannot use the enlarged (10%) plans to make a 60 size version. SPA will only allow a 3% or less deviation from the original size. Bummer. I prefer the .60 size version, but now I'll have to consider whether of not to build the original 55" wing version and power it with my OS.55AX. If I decide NOT, I'll have to decide on another plane. Maybe a Deception or a Dirty Birdi.

ChiefK

That OS 55 ax is conciderably stronger that some pipped engines of back in the 70s. The Mustang X with that engine will pull through just about any manuver.
Terry

Chiefk,

Enlarge the wing/stab 3% or so. Stretch thenose andrear end3% or so.Look at some of those redesigns of theDirty Birdi withan OS 91S on the nose andtell me they are only 3% changed. Uh huh!

Terry in LP

Maybe so. I understand that Jim Kirkland used the original Mustang X with a ST .46 to win a second place at the 1971 Nationals. So clearly, the airplane is capable. Maybe it's only the pilot that needs to grow 10%.

ChiefK

I don't think you have to add length to the nose, but I would add 3 inches to the tail moment! This seems to be the standard "mod" to SPA aircraft.

Jon

Greg,

Or you could build a beautiful Deception - an outstanding pattern ship - and have the 3" stretch already taken care of.

I'm starting to wonder if Jim's Deception was one of the earliest SPA aircraft with an almost square planform. Attached photo of my reduced 30 size, 48" span plans.

David.

David,</p>

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Greg</p>

<div style="margin: 0in 0in 10pt">One would think if they don&rsquo;t notice 3&rdquo; added to the tail they most likely wouldn&rsquo;t notice the lack of gear hanging down in flight or a pipe slung under the wing!!!</div><div style="margin: 0in 0in 10pt"></div><div style="margin: 0in 0in 10pt"></div>

I'm sure there would be many cries of "FOUL".

Greg

<div style="margin: 0in 0in 10pt">If I was judging, I&rsquo;d give you extra points!!</div><div style="margin: 0in 0in 10pt"></div><div style="margin: 0in 0in 10pt"></div>

The nice thing about down here in Florida is you can do it both ways! And use the same airplane, for SPA just leave the gear down! It was a hoot watching Chip Hyde fly the BPA pattern back in December, Tangerine pattern contest. His "break right for landing" really WOWed the crowd.

Jon W

Greg,

I seem to see the plan fine - actually a little large. Is it still appearing broken at your end?

I'm not sure what RCU has done but it seems that the reduction of frame size in photos (jpg's) to include in posts is working in a random fashion. This has happened in the past but lately it seems to be more often than not. Ever since the change of the post window headers to include word like editing fuctionality. Inoticed that Crankpin was also commenting about this.

David.</p>

For those interested, attached is the PDF of the 30 size version. As usual, save as Deception-30.pdf.

Thanks to raindave for a handy utility that produces light PDF files!

David.

Got it now.....

Thanks

Greg

Whoo, hooo!

just picked up one of these rare beasts - NIB! Been wanting one for quite some time...

I can think of at least 4 projects well suited for this engine starting with the plans in the post above! For an upright engine installation, do you guys think a 15 deg Mac's header would work or is a fuse top header more appropriate?

For an inverted engine installation, Iwould require an S shaped header. Any one have an MKSkymaster they'd like to part with?

David.

"I don't think you have to add length to the nose, but I would add 3 inches to the tail moment! This seems to be the standard "mod" to SPA aircraft.

Jon"


Oh, 'scuse me. I thought it was 3% but I guess it's 3 inches.

Terry in LP

i have an OS V .61 rear exhaust but i've never investigated it's capabilities. any thoughts?

David,

Iassume you mean a 61 VF? There was also the 61 VRDF. Engine vintage is probably 1979.

Nice engine and good question. Aside from timeframe, I'm not sure how exactly the VF differed from the RF but Ipresume it was timed for smaller props and higher RPM output (VF 11x8 - 1.8 bhp@17K).

Also, the V series engines had a 2 piece crankcase whereas the RF and SF had a once piece crankcase. In any case, a pure ballistic pattern engine! Also, essentially the big brother of the 25 and 45 VF and a perfect candidate for a Magic or a Deception to my mind. The 25 VF is of a little later vintage - 1982 according to the OS history timeline. The 25 SF didn't come out until 1989 - 7 years later!

In terms of its capabilities attached is the OS PDF manual (save as .pdf)

David.

David,  as i understand it there was a V model (well, i have one) and then there came the VF (i think).  either way, the high revs are what i bought it for.</p>

</p>

David,

For as long as I can remember and based on OS's engine history timeline:

http://www.osengines.com/history/ostimeline07.html

they have always used a two or three letter nomenclature to designate intake and exhaust configurations of engines. The V series engines were no different and they used the V to designate the rear exhaust configuration possibly due to the port design. Whether engines were VF or VR meant they were Front intake or Rear intake. The VF's, at least in the 60 class sizes, were, according to their manual, meant for:

"The O.S. MAX-61 VF is a high performance engine that has been
developed expressly for FAI type R/C contest models. It employs
schnuerle scavenging and a rear exhaust port to facilitate
the installation of a tuned silencer system, especially where the
latter is to be built into the fuselage."

The VR's were typically designed for a ducted fan with the carburetor on the backplate. Whether and engine was a DFor not also depended on timing and bore/stroke. The FSR/RSR and SF/RF series are similar with respect to the nomenclature.

David.

 mine just has a V on the side.  but it is a rear exhaust.

Yup! the crankcase wasn't distinguished between the VF and VR because they were one and the same so they were just designated V-series. The internals and the front and back would change depending on whether they were front or rear intake.

As can be seen from this picture, the 25 VF is also just designated "V" but in this case it is actually a VF DF. The 25's were never made with rear intake, hence no VR models of this engine but there were two versions (internal porting and timing); the VF ABC and VF DFABC.

David.

thanks david.