Here is a high level description of a ARKit skywriting concept.
A short (~3-20 characters) line of text can be entered by a user in a form field and have a 3D airplane draw the text in the sky or in the room. The sky or room mode should be selectable at the moment (a will be determined programmatically later on) so that the perspective and angle of the text makes sense. If a user is indoors then the plane will be a small toy plane drawing the message with smoke letters that are perpendicular to the ground so they appear straight up vertical in front of and parallel to the viewers position.
If the user is outdoors, a regular sized biplane would draw the message at an angle where the user can point the camera view up to the sky to see the cloud lettering. For sky writing, the plane has to make various maneuvers that are unique to each letter. The letter "A" for example would require 3 passes, one for each side of the letter and another pass for the middle section. The letter "B" would also require 3 passes, one for the left bar and 2 for each rounded half circle on the right. We can limit the number of letters for this trial if having custom animations for each letter will be too time consuming. Let me know how many letter animations would be reasonable for one week project. We would need at least 3 letters to perform a decent set of tests. I've seen skywriting with a continuous stream and with isolated dots of clouds to create the letter strokes. Continuous stream of smoke is preferred. We can use freely available existing plane models for this job and later replace with better models if needed. I believe the particle system in SceneKit could work for the smoke but you tell me if you have other ideas.
Let me know if this is something you are able to create and the cost.
Send me questions.