Cobra (oz11636)
About this Plan
Robbe Cobra. Radio control sailplane model. Wingspan 2.2m.
Quote: "Hello Mary, hello Steve, Here is the plan for the ROBBE Cobra, an easy to build, yet rather elegant beginner's 2 channel sail plane. Span is 2,20m. It's from a kit my father bought and built sometime in the 70s. B/R Hubert"
Direct submission to Outerzone.
Update 9/12/2024: Added kit instructions, also a review from FMT, thanks to Frank Deecke.
Quote: "Cobra - a glider model from Robbe.
About a year ago I bought the 'Cobra' kit from Robbe. The model is made of wood and has a wingspan of 2.2 meters. This makes it a handy model that can be easily transported in any trunk. The wings are put together with steel rods and strapped to the fuselage with rubber bands. The widely used Clark-Y is used as the profile.
Kit - construction of the model: The contents of the kit make a good impression. The plan is clear. The construction description, which is divided into individual construction sections, means that there are no problems with assembly. The wooden parts are all punched out or printed and numbered in the kit. The quality of the wood was consistently good. I completed the model in about 4 weeks. The fuselage is built as a simple box fuselage. In contrast to the construction plan, I reinforced the first half of the underside of the wings with a Wood planking. I didn't glue the horizontal tail unit to the fuselage, but attached it with rubber bands so that it wouldn't be torn off in the event of a hard landing. This has also proven to be very effective. Paper was chosen as the covering, as tears and holes in this type of material are easy to repair. Finally, I installed a Robbe Terra, which is used to control the rudder and elevator. There is enough space in the model for the remote control, so that any commercially available make can be used.
Flight testing: On the first day of flying, I felt a little queasy at first. First I checked everything again. Then came the big moment. The rubber band was pulled out and the model was hooked in. Off we went! It rose steeply, but only for a few seconds. The band came loose from the model at a height of around 10 m and my Cobra then went into a nosedive. Despite this, I still managed a fairly soft landing. I soon saw what had happened: the skid, which also serves as a high-launch hook, had broken off. The skid construction made of glued pine strips proved to be too weak. At home it was replaced and a metal hook was screwed into the fuselage for high-launch. Since then, there have been no more problems with the rubber rope launch.
The model has a good glide angle and is easy to control even in strong winds; you just have to make the Cobra go a little faster with the elevator trim.
Flying with the Cobra is easy. When it stalls, the model starts to pump and only after it has been starved does it tip over over a surface, but it can be caught again very quickly. You can also do simple aerobatics with the Cobra. I have been flying the model with a motor attachment and a 1.7 cc engine for some time. It reaches heights where it is almost impossible to see. Even without thermals, you can then sail for a quarter of an hour. The Kobra is an easy-to-build model that can be mastered by beginners and, at under a hundred marks, is not too expensive. Holger Munk."
Supplementary file notes
Instructions.
Review.
Corrections?
Did we get something wrong with these details about this plan (especially the datafile)?
That happens sometimes. You can help us fix it.
Add a correction
Do you have a photo you'd like to submit for this page? Then email admin@outerzone.co.uk
User comments
No comments yet for this plan. Got something to say about this one?Add a comment
- Cobra (oz11636)
- Plan File Filesize: 430KB Filename: Cobra_RC_oz11636.pdf
- Supplement Filesize: 665KB Filename: Cobra_RC_oz11636_instructions_de.pdf
- Supplement Filesize: 613KB Filename: Cobra_RC_oz11636_review_FMT.pdf
- help with downloads
Notes
* Credit field
The Credit field in the Outerzone database is designed to recognise and credit the hard work done in scanning and digitally cleaning these vintage and old timer model aircraft plans to get them into a usable format. Currently, it is also used to credit people simply for uploading the plan to a forum on the internet. Which is not quite the same thing. This will change soon. Probably.
Scaling
This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.
Terms of Use
© Outerzone, 2011-2025.
All content is free to download for personal use.
For non-personal use and/or publication: plans, photos, excerpts, links etc may be used, provided that full and clear credit is given to Outerzone with appropriate and specific direction to the original content i.e. a direct hyperlink back to the Outerzone source page.
Unauthorized use and/or duplication of this material without express and written permission from this site's owner is strictly prohibited. If we discover that content is being stolen, we will consider filing a formal DMCA notice.