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retractable gear on RVs?

diamond

Well Known Member
Sorry if this is dumb, but I'm at the bottom of the learning curve. With all the mods I read about for RVs, is there a mod for retractable landing gear, especially for the taildragger -7 or -9? If so, other than looking cool in the air, what is the upside and downside of doing this? Thanks
 
Recommend you use the search function.
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Search, advanced, retract, search titles only, Wallah

You can do the same for retractable, or other terms of interest.
Start with titles only, move on to posts if you dont like what you get.
You will find much material.
 
Retractable Gear in an RV

Several years ago Kitplanes (or EAA Sport Aviation mag) had a feature on a guy in Germany adding retractable gear to an RV. He had both a retractable and fixed and after a ton of work, the retractable gear added about 2-3 knots to the total speed. The article was interesting to read and the technical obstacles overcome were formitable, but bottom line is the fixed gear is very efficient with the proper fairings.

S S Anderson
RV 7A Flying
Await kid graduation to buy more avgas
 
Several years ago Kitplanes (or EAA Sport Aviation mag) had a feature on a guy in Germany adding retractable gear to an RV. He had both a retractable and fixed and after a ton of work, the retractable gear added about 2-3 knots to the total speed. The article was interesting to read and the technical obstacles overcome were formitable, but bottom line is the fixed gear is very efficient with the proper fairings.

S S Anderson
RV 7A Flying
Await kid graduation to buy more avgas

Burt Rutan determined the same thing many years ago with his canard airplanes. It simply is not worth the complexity and cost to do it. If we flew at 400 knots it would be another matter entirely, but not at the speeds we fly.

The cost of maintaining the retraction system is much over the years. Every annual the certified retracts have to be swung plus insurance premiums are always higher as there is some truth to the saying there are those who have and those who will - land gear up.

The only thing that prevents it in big airplanes is a checklist, another crew member reading it, and the death penalty if you don't. :)
 
Upside is 2-3kts, less fiberglass work which some seem to hate with a passion, and easier tire inspections. Short of a major new finding in cooling drag, this may be one of the last places to pick up knots after the aft cowling fairing.

Downside is designing and engineering your own solution, as there aren't any ready-made mods that I'm aware of. You might be able to kit-bash from another plane, but you'll still have to incorporate that design in and really test it out.

I would think it'd be easier than the stretch 6. If you want it bad enough, it's not insurmountable. It would be a big undertaking however.
 
There you are

Pics taken on the 2nd RV meeting in Damme, Germany. I hope the owner doesn`t mind me posting these.

dsc05013x.jpg

dsc04985l.jpg
 
Retractable tailwheel too...

Very well done example but I'm guessing an additional 250 lbs or more. I also read that this airplane cruises right at VNE, not just 2-3 knots faster.

Regards,
 
Very well done example but I'm guessing an additional 250 lbs or more. I also read that this airplane cruises right at VNE, not just 2-3 knots faster.

Regards,

Possibly - but that's a function of power as well - and with that 3-blade prop the obvious question is what engine is installed?
 
Downside is designing and engineering your own solution, as there aren't any ready-made mods that I'm aware of. You might be able to kit-bash from another plane, but you'll still have to incorporate that design in and really test it out.

Another downside not mentioned is the placement of the fuel tanks farther outboard.
 
That 'ole boy has been tinkering with a lot of things...for example, check out the cooling air exit area and exhaust system.
 
If you really feel the need for retract, I would suggest you go with an aircraft designed around that capability. The RV is a great compromise airplane (all airplanes are compromise) with reasonable speed, great short and rugged field landing capability, and easy maintenance.

Maybe you're thinking you could build a retract RV for less than one of those "other planes?" Well, maybe - but I would guess that all the work and special parts you would need would push you up towards the cost of one of those others, as well as move the build time pretty close, too.

Note that I fly one of those "others;" however, I always recommend prospective builders / buyers start with their no-kidding mission requirements and a budget before shopping for an airframe.
 
Very well done example but I'm guessing an additional 250 lbs or more. I also read that this airplane cruises right at VNE, not just 2-3 knots faster.

Regards,
Pierre

IIRC the story about this German RV-4RG...

This was the second RV-4 he built and the article compared this one to his FG RV-4.

The RG was something like 80 pounds heavier and only 4 knots faster.

Not worth the effort, IMHO, but it sure looks cool. Notice the gear doors and retractable tailwheel.

The story went into detail on the German requirements for engineering data prior to certification and flight. The wheels retract in front of the main spar, thus the leading edge angles forward so the wheels will fit. There are also some modifications to the spar to take up the extra weight and the flexing caused by the gear being mounted out on the wings.

All in all, a very cool mod!
 
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I've wanted to do the same thing. More like a Harmon Rocket with retract though. It just looks so bad ***....
 
Oh my, it looks like a Mustang landing gear setup. VERY cool.

I do believe that it was mentioned that the next F1 Rocket might have provisions for Retracts :)
 
Here`s 2 more pics I found - you can`t really see it but as far as I remember the wings were heavily modified on the inside (i.e. rivet pattern, ribs, spar, etc).
The 2 silencers can be found on many airplanes over here, they`re built by a company called "Liese". The noise....

Enjoy:

dsc04987n.jpg

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Retracts aren't needed..

...as the RV's have proven. We stomp Bonanzas, Mooneys and Comanches by a pretty big margin.

I've run down Mooneys and a Comanche and my buddy has way outrun a Bonanza by 12 MPH in his -10. The KISS principle works well here.

Regards,
 
The KISS principle works well here.

Regards,

Well who said it had to make sense? I see all sorts of opinions that something like this violates the KISS principal while at the same time an equal number of advocates are chomping at the bit for every electron driven gizmo they can get a second mortgage to afford installing in their star wars inspired panel....

I agree that a retract RV doesn't make a lot of practical sense but the vast majority of the population thinks a homebuilt airplane lacks a certain conventional rationality as well.

I just think there is something cool about the wheels going goodbye as an airplane climbs out. Unfortunately I probably will enver sink my time and money into making one but I'm sure glad someone did if only for the pleasure of looking at the pictures....

Here's to the real dreamers among us!
 
Well now. If I had the drawings for that -4 I'd probably build folding rollers into mine. I just don't have the engineering capability myself to design it. I sure have access to all the stuff to make the parts :D
 
Retractable RV-4

Sorry if this is dumb, but I'm at the bottom of the learning curve. With all the mods I read about for RVs, is there a mod for retractable landing gear, especially for the taildragger -7 or -9? If so, other than looking cool in the air, what is the upside and downside of doing this? Thanks

The RV-4 with retractable gear is built by Klaus Roth in Germany and his email address is [email protected].
 
RV Retractable

My father built a retractable RV8 and it was published twice in the rviator. He recently began restoring the original fixed gear design in order to simplify the airframe, planning to sell it soon. He is building an RV12 to fit his flying taste at 79 years of age. He really never measured the speed. The additional weight was not anything near 100lbs (much less). He placed a hydrolic pump in the rear of the fuse that operated the gear. The interior gear doors and associated latching mechanism were manually operated. The complexity of maintaining a reasonable CG required a design that both lowered and cantered forward....certainly a complex design that took him several designs and a couple of years to get right. The fuel tanks were moved outboad; another task but not as challenging as the gear movement.
 
If you want to see what's involve in doing something like this, Sport Aviation had several articles about guys adding retracts to Thorp T-18s and Mustang IIs. do a search in the Sport Aviation archives for "retract" or "retractable" in the title. Also, on the mustangaero yahoo group, someone posted a set of plans on how to add retracs to the Mustang II.
 
What I have found out.

There is a another example discussed with photos on VAF: http://www.vansairforce.com/community/showthread.php?t=8071&highlight=landing+gear

I also have the Kitplanes article mentioned earlier in front of me.

I think the speed advantage is somewhat understated. I've read somewhere about the Bryan Carr built example cruising along at way above Vne. The kitplanes article give comparisons between the two Klaus Roth RV4's which are identical except for the gear. Flying the two side by side shows a difference in manifold pressure of two inches Hg, which in my mind is not insignificant!

Some other information that might be of interest is the Klaus Roth RV4 is O-360 180 hp, MT 3-blade prop, weighs 1132 lbs. That compares with his fixed gear RV4, same power plant package at 1022 lbs. The retractable example also had inverted fuel and oil.

The fuel is still in the wing leading edge, but moved outboard.

Cheers,
Andrew.
 
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