stunthanger.com

Speed,Combat,Scale,Racing => Combat => Topic started by: Ara Dedekian on August 29, 2016, 06:24:29 AM

Title: A Tom Niebuhr Scorpion
Post by: Ara Dedekian on August 29, 2016, 06:24:29 AM

       I was given a Nemesis II and a Tom Niebuhr Scorpion that need recovering. Both airframes are pristine but the old silkspan covering has become quite brittle. There are no signs of them having been flown. The Scorpion, although having tip weight, balances evenly on the fuselage centerline. It appears to have been built as per the plans as shown on the B. Baxter site and perhaps the recommended tip weight? Should I be adding more tip weight? Also, the uncovered wing is torsionally quite rigid. Should I add sheer webs? Anyone have any experience with this design? It will be used as a sport flyer with an Enya 29 with pressure.

Ara

Title: Re: A Tom Niebuhr Scorpion
Post by: john e. holliday on August 30, 2016, 10:13:05 AM

If you recover with silk you should not need sheer webs.   Now when you add the engine you will find out it will not balance on center line of the wingspan. H^^

Title: Re: A Tom Niebuhr Scorpion
Post by: Ara Dedekian on August 31, 2016, 05:14:28 AM

         John

            I planned on recovering with Monocoat just to get it off the bench in a hurry and move on to the next project. So I will add 1/32" sheer webs to give it a bit more strength and keep the tip weight as is.

         Thanks for the help.
         Ara

Title: Re: A Tom Niebuhr Scorpion
Post by: Russell on September 01, 2016, 06:56:22 AM

I bought the plans from Aircraft Modeler around '72/'73 when the article came out on the Scorpion and remember the spars being spruce and if the trailing edge balsa was soft to add webs between the ribs on just the TE. I never stayed with the Scorpion because it did not fly like the Nemesis II that I started using about six months prior.

Title: Re: A Tom Niebuhr Scorpion
Post by: Ara Dedekian on September 12, 2016, 06:53:29 PM

        CL-flyer

             Thanks for that info. Just checked the uncovered wing (got distracted) and the spars are spruce and shear webs were placed on the trailing edge as you remembered. What's interesting is that it was built by a prolific builder who built everything from hand launch gliders to giant scale RC but didn't fly C/L Combat. Was the sheer web suggestion on the plans? I'll cover it as is.

        Ara

Title: Re: A Tom Niebuhr Scorpion
Post by: Russell on September 13, 2016, 04:14:02 PM

Quote from: Ara Dedekian on September 12, 2016, 06:53:29 PM

        CL-flyer

             Thanks for that info. Just checked the uncovered wing (got distracted) and the spars are spruce and shear webs were placed on the trailing edge as you remembered. What's interesting is that it was built by a prolific builder who built everything from hand launch gliders to giant scale RC but didn't fly C/L Combat. Was the sheer web suggestion on the plans? I'll cover it as is.

        Ara

The leading edge is also spruce. The shear web info is in the article which I scanned but is too large to attach, but was able to attach plan.

Title: Re: A Tom Niebuhr Scorpion
Post by: Russell on September 13, 2016, 04:38:42 PM

Scorpion article attachment.

Title: Re: A Tom Niebuhr Scorpion
Post by: Ara Dedekian on September 14, 2016, 05:09:48 AM

        Thanks CL-flyer for taking the time to forward the plans and article. Nice to have the background on the development of the design. Looks like I have a plans built, box stock Scorpion that should be covered in silk (or Polyspan?), as John recommended, and not compromise the original design parameters.

Ara