The Tip-Tow project, MX-1016, a contract with Republic Aviation, was one of a number of experiments undertaken during the late 1940s and into the 1950s. The object of the experiments was to find some method of increasing the notoriously short range of the first generation of jets to enable them to accompany the piston-engine bombers which enjoyed up to three times the range of the jets. Other experiments included the XF-85 Goblin, intended to be carried in one of the bomb bays of a B-36, the RF-84K FICON slung by trapeze under a B-36 (which was operational for about a year), the Tom-Tom using RF-84F and B-36 in a scheme similar to Tip-Tow. The other, and ultimately successful experiments, were the drogue-and-probe and flying-boom refueling methods, both of which have been standard procedure for some sixty years.
The Tip-Tow project consisted of two Republic F-84D Thunderjets and a B-29 which were modified to enable the F-84s to wing-couple to the B-29. The Thunderjets modified for the experiment were EF-84D-1-RE 48-641 and 48-661; the mother ship was ETB-29A-60-BN 44-62093. 48-641 was the left hand F-84, piloted by Major John Davis; 48-661 was the right hand F-84, piloted by C.E. “Bud” Anderson of the P-51D “Old Crow” fame.
There were many preliminary flights leading up to the most successful with both Thunderjets coupled to the B-29 and all using manual pilot control. That flight, on 20 October, 1950, lasted 2hr 40min. Based upon that success, the decision was made to proceed with a system of electronic feedback flight control. The modifications were accomplished by 1953, and several test flights were made to test the electronic connections. At the last flight, the right hand F-84D was successfully coupled and towed, but no electrical connections were made with the B-29, so that F-84 uncoupled. The left hand Thunderjet successfully coupled, electrical connection was established, and the automatic flight control system was activated. The EF-84D immediately flipped up and over onto the B-29 resulting in both aircraft crashing with all crew members killed. The project was immediately terminated.
I built a model of Tip-Tow in 48th by kitbashing two Tamiya F-84G kits shortened 15″ in scale and scratch building the respective right and left wing-tip coupling parts. I modified a Monogram B-29 by scratch building the wing-tip coupling parts to carry the Thunderjets. Appropriate flight crew is modeled for the three aircraft. The decals were created using PhotoShop and printed with an Alps printer. Square brass tubing spans the inside of the B-29 wings and square brass tubes in the F-84 wings insert into the tubes in the B-29 wings. I added 12v electric motors to the B-29 model. A friend built the stand for me and I added a photo gotten from a land survey company to represent the Long Island farmland over which the flights were conducted.
This link has a photo of the Tip-Tow Project taken on 20 October 1950. Note that the photo incorrectly identifies it as “Tom Tom” rather than Tip-Tow. https://en.wikipedia.org/wiki/File:Boeing_B-29_TomTom.jpg
8 additional images. Click to enlarge.