Have you ever heard one of those ideas that make you want to grab a beer and try to forget you ever heard it?

This could easily be the case for you when you check out the McDonnell XF-85 Goblin parasite fighter.
http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2330

If you read the above link you will find out that the purpose of the Goblin was to be dropped from a bomber to ward off interceptors then be pulled back into the bomber's bay. For this purpose, the Goblin is an absolutely tiny jet 'fighter'.

Keep in mind when I say tiny I mean the pilot is straddling the jet engine with the 4 50cal MGs immediately in front with the tail surfaces immediately behind the pilot...immediately..
The Goblin thus has a 21 foot wingspan when the wings are unfolded, a length of around 14ft, a height of 8ft, and a weight of around 5,000lbs (depending on the source of your info). For comparison, the typical USAF jet fighter of that era (post war) that was already in service was the F-84 (Sabre was a skosh later):
http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2294
Note that the F-84 is a full 3x heavier, the Goblin's wingspan is just 58% of the F-84 Thunderjet's, only 37% of the F-84s length, and 2/3s the height of the F-84...now that is a tiny jet!
Despite the tiny dimensions the wings of the Goblin still had to be folded to fit inside one of the bomb bays in the B-36 Peacemaker's (the largest bomber to enter service at the time).
http://en.wikipedia.org/wiki/B-36

Keep in mind that the Goblin was first flown in 1947 and that bomber pilots of the day were veterans of World War 2. Thus many were deeply interested in maintaining fighter escort capability if they were to fly their lumbering B-36 into the heart of the Russian defenses. The problem with that is the B-36 had a range that far exceeded the best fighters available. Air to Air refueling was not yet established, so the DoD crazies dreamed up the idea of the bomber carrying its own escort.
Believe it or not, this was not a new idea nor would SAC (Strategic Air Command) be the first to try. Most attempts to carry parasite fighters was simply to extend their range, much like the Mercury-Maia combination of mailplanes. These other parasite fighter concepts entailed some memorable examples such as the USS Macon and USS Akron airship aircraft carriers:
http://www.airships.net/us-navy-rigid-airships/uss-akron-macon
the Luftwaffe Mistels:
http://www.warbirdsresourcegroup.org/LRG/mistral.html
and my favorite, the Zveno Project:
(for Il-2 Sturmovik 1946 users, you can try the Mistels and Zveno aircraft yourself)
http://www.unrealaircraft.com/forever/vakhmistrov.php
I should note that the Mistels were more of an air-launched cruise missile than a parasite fighter. Thus the Zveno fighters were the only operational and SUCCESSFUL parasite fighters. The parasite fighters though in this case were carried for the sake of increasing range so the fighters could strike a target beyond their normal range.

So from the point of view of being carried and air dropped, the Goblin is nothing new...however, the crazy bit is that the Goblin would re-connect with the bomber and be pulled back into the bomber's bay.
Why is that crazy? For one: close formation flying. The Goblin would be retracted via the Goblin hooking on to a little trapeze hanging from the B-36...with the hook on the Goblin being right in front of the pilot's head.
Finally, anyone with a basic understanding of fluids knows of a thing called a wake...so imagine the tiny tiny Goblin trying to fight its way through the gigantic B-36's wake to hook up on the trapeze..

In practice the only 2 Goblins only flew with B-29 motherships rather than the huge B-36 that was planned. Still, the B-29s wake threw the little Goblin all over kingdom come making it virtually impossible. Very very few 'captive' flights were flown. On one attempt the trapeze hit the canopy of the Goblin knocking off the pilot's helmet and O2 mask, that flight thankfully ended with a skid landing (the Goblin had skids instead of gear).
Thus after just about a year of testing the wee little Goblins were quietly retired to museums.
SAC however took this concept to a more meaningful level via the FICON program which saw an RB-36 carry one RF-84 for the sake of extending the RF-84's range for recon missions. The much larger RF-84 proved much better at handling the bomber's wake and thus it was used for a couple of years (albeit in a limited role). On that note apparently a distant relative of mine was a flight engineer on the FICON B-36 motherships... I have only met him once, but dang that was an awesome 4hr conversation! 
http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=587

I cannot find a lot meaningful info on the flight characteristics of the Goblin. Although it does seem like it was a very pleasant little aircraft to fly. Still, with a low top speed, tiny fuel capacity, and only 4 machine guns, it is unlikely a F-85 could face off against a Mig-15 and expect to be successful.

Alright, I think I have rambled enough for this one...I will end it by saying if you ever get a chance to see one of the two Goblins at the National Museum of the USAF TAKE IT! It is such a unique and frankly cute little jet it is a must-see. First time my dad and I saw it we instantly broke out laughing. "Aww look at the cute little fighter  " 


I will now leave you with this wonderful 10min video of the program:
http://www.youtube.com/watch?v=bmaPnpH7CIg

Tailwinds,

Adam

Amr149 wrote on Oct 30^th, 2012 at 1:29pm:


Yes sir, a gigantic flop of a project but where would aviation be today with out these wonderful flops?